Program Handbook

Transcription

Program Handbook

The 3rd International Gravity Field Service (IGFS)
General Assembly
(IGFS 2014)
June 30 - July 6, 2014, Shanghai, China
http://202.127.29.4/meetings/igfs2014
Venue: 3rd floor of Astronomical Building
Shanghai Astronomical Observatory, Chinese Academy of Sciences
The 3rd IGFS
(International Gravity Field Service)
General Assembly
June 30-July 6, 2014, Shanghai, China
http://www.shao.ac.cn/meetings/igfs2014
Contact Information:
Email: [email protected]; [email protected]
Emergency Phone: 13918401214
Police: 110; Ambulance: 120
Venue: 3rd floor, Astronomical Building
80 Nandan Road, Shanghai 200030, China
Available WIFI at the workshop with the password at conference hall doors
Sponsors
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International Gravity Field Service (IGFS)
International Association of Geodesy (IAG) Commission 2
Shanghai Astronomical Observatory (SHAO), CAS
Center for Space Geodesy, China Univ. of Mining & Tech.
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Scientific Organizing Committee (SOC)
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Riccardo Barzaghi (Politecn. di Milano, Italy) (Chair)
Sylvain Bonvalot (BGI, France)
Carla Braitenberg (University of Trieste, Italy)
Rene Forsberg (DTU, Dennmark)
Shuanggen Jin (SHAO, CAS, China) (Co-Chair)
Jiancheng Li (WHU, China)
Urs Marti (Swisstopo, Switzerland)
Roland Pail (TUM, Germany)
Dan Roman (NOAA, USA)
Michael Sideris (University of Calgary, Canada)
Local Organizing Committee (LOC)
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Wenli Dong (SHAO, CAS, China)
Guiping Feng (SHAO, CAS, China)
Shuanggen Jin (SHAO, CAS, China) (Chair)
Xiaoya Wang (SHAO, CAS, China)
Topics
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Gravimetry and gravity networks (Bonvalot, Roman)
Global geopotential models and vertical datum unification (Sideris, Li)
Local geoid/gravity modeling (Marti, Barzaghi)
Satellite gravimetry (Pail,Jin)
Mass movements in the Earth system (Forsberg, Jin)
Solid Earth Investigations (Braitenberg, Forsberg)
Full papers for the "IAG Book Series", Springer (indexed in ISI Web of Knowledge):
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All abstracts accepted and presented at the Assembly (oral or poster) may be submitted as papers for
publication in the official peer-reviewed IAG Symposia Series at Springer Publisher. Manuscripts for
possible publication in the proceedings have to be submitted for peer-review through the IAG
Symposia Editorial Manager following the INSTRUCTIONS FOR AUTHORS supplied therein.
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Deadline of full paper submission：September 30, 2014
Contacts on full paper submission ： Shuanggen Jin ([email protected]) ； Riccardo Barzaghi
([email protected])；Pascal Willis ([email protected])
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Dear All Participants
The 3rd IGFS General Assembly, that will take place in Shanghai, June 30 th – July 6th, 2014, at the Shanghai
Astronomical Observatory (SHAO), Chinese Academy of Sciences, will be devoted to these topics. The focus
of the Assembly is on methods for observing, estimating and interpreting the Earth gravity field as well as its
applications. The Assembly is organized by SHAO, the International Gravity Field Service (IGFS) and the
Commission 2 of the International Association of Geodesy (IAG). IGFS is an official IAG Service which
coordinates and harmonizes the activities of other "Level 1" gravity related Services, namely the Bureau
Gravimetrique International (BGI), the International Geoid Service (IGeS), The International Center for Earth
Tides (ICET), the International Center for Global Earth Models (ICGEM) and the International Digital
Elevation Model Service (IDEMS). IAG Commission 2 is a scientific body of IAG that was established to
promote and support investigation related to the gravity field of the Earth and its temporal variation.
On behalf of the Organizing Committee, we are pleased to invite you to attend the 3rd International Gravity
Field Service (IGFS) General Assembly (IGFS2014), June 30 – July 6, 2014, Shanghai, China. For any
questions, please feel free to contact LOC at http://202.127.29.4/meetings/igfs2014.
Sincerely yours
Prof. Riccardo Barzaghi & Prof. Shuanggen Jin
On behalf of the Organizing Committee,
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Astronomical Building of Shanghai Astronomical Observatory, CAS
25m radio telescope, 1.56m reflector, SLR, GPS etc. at SHAO
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1. Schedule of the 3rd IGFS 2014 General Assembly
Time
30-Jun-14
1-Jul-14
2-Jul-14
3-Jul-14
4-Jul-14
5-Jul-14
09:00-09:15
Opening
Session 2
Session 3
Session 4
POSTER
09:15-09:30
IGFS
Session 2
Session 3
Session 4
(SESSIONS
09:30-09:45
BGI
ICGEM
IGeS
ICET
Session 2
Session 3
Session 4
4,5,6)
Session 2
Session 3
Session 4
(18
Session 2
Session 3
Session 4
POSTERS)
Session 2
Session 3
Session 4
Break
Break
Break
Break
Session 2
Session 4
Session 5
Session 6
Session 2
Session 4
Session 5
Session 6
11:30-11:45
Session 2
Session 4
Session 5
Session 6
11:45-12:00
Session 2
Session 4
Session 5
Session 6
Session 2
Session 4
Session 5
Closing
12:15-12:30
Panel
Discussion
Session 2
Session 4
Session 5
Session
12:30-14:00
Lunch
Lunch
Lunch
Lunch
Lunch
14:00-14:15
Session 1
Session 3
Session 5
14:15-14:30
Session 1
Session 3
Session 5
09:45-10:00
10:00-10:15
10:15-10:30
Group Photo
10:30-11:00
& Break
Plenary
Session
11:00-11:15
11:15-11:30
12:00-12:15
SOCIAL
14:30-14:45
Session 1
Session 3
14:45-15:00
Session 1
Session 3
Session 5
15:00-15:15
Session 1
Session 3
Session 5
15:15-15:30
Session 1
Session 3
Session 5
Break
Break
Break
15:30-16:00
Registration
16:00-16:15
Session 1
16:15-16:30
Session 1
PROGRAM
Session 5
Session 6
Session 6
POSTER
SOCIAL
16:30-16:45
Session 1
SESSIONS
PROGRAM
16:45-17:00
Session 1
1,2,3)
Session 6
17:00-17:15
Session 1
(21
Session 6
17:15-17:30
Session 1
POSTERS)
Session 6
Banquet
18:00-19:00
19:00-20:00
Ice Breaker
IGFS
(Ronggang
Meeting
Restaurant
Commission
Room
2 meeting
527-529)
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Session 6
6-Jul-14
Session 6
Session 6
Free
activities
2. Program of the 3rd IGFS 2014 General Assembly
Monday 30th June 2014
14:00-17:00
Registration (Third floor of SHAO)
Tuesday 1st July 2014
07:30-17:00
09:00-09:10
09:10-10:20
09:10-09:20
09:20-09:35
09:35-09:50
09:50-10:05
10:05-10:20
10:20-10:50
10:50-12:30
10:50-11:20
11:20-11:40
11:40-12:00
12:00-12:30
Registration (Third floor of SHAO)
Opening Ceremony
Chair: Shuanggen Jin
Panel Session A (Room A)
Chair: Riccardo Barzaghi
IGFS: International Gravity Field Service
Riccardo Barzaghi (Politecnico di Milano, Italy)
The International Gravimetric Bureau (BGI) : tasks and objectives
The ICGEM: an IAG Gravity Field Service
Franz Barthelmes (GFZ-Potsdam, Germany)
The International Geoid Service: present status and future perspectives
Mirko Reguzzoni (Politecnico di Milano, Italy)
International Centre for Earth Tides - ICET
Jean-Pierre Barriot (Geodesy Observatory of Tahiti, Tahiti)
Take Group Photo at first floor & Coffee Break
Panel Session B (Room A)
Chair: Shuanggen Jin
Gravimetry Research in China: Progress and Outlook (Keynote)
Houze Hsu (Ins. Geodeys & Geophysics, CAS, China)
GOCE Gravity Field Models – Overview and Performance Analysis
Thomas Gruber (TUM, Germany)
A new time-varying gravity field from GNSS and ocean observations for 1998-2013
Shuanggen Jin (SHAO, CAS, China)
Panel discussion (Riccardo Barzaghi, Sylvain Bonvalot, Franz Barthelmes, Mirko Reguzzoni,
Jean-Pierre Barriot, Houze Hsu, Thomas Gruber)
Lunch (Cafeteria, 2nd floor of Active Center Building)
14:00-15:30
14:00-14:15
14:15-14:30
14:30-14:45
14:45-15:00
Session 1A: Gravimetry and Gravity Networks (Room A)
Chair: Sylvain Bonvalot, Vojtech Palinkas
Airborne gravimetry for geoid and GOCE
Rene Forsberg (DTU, Denmark)
Airborne gravity for an improved New Zealand quasigeoid
Matt Amos (National Geodetic Office, New Zealand)
Improving estimability in strapdown airborne vector gravimetry
David Becker (Technische Universitaet Darmstadt, Germany)
An Airborne Gravimetry Test of SGA-WZ in Greenland
Lei Zhao (NUDT, China)
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15:00-15:15
15:15-15:30
15:30-16:00
16:00-17:30
16:00-16:15
16:15-16:30
16:30-16:45
16:45-17:00
17:00-17:15
17:15-17:30
Testing airborne gravity data in the large-scale area of Italy and adjacent seas
An approach for determining the geopotential based upon coaxial cable time transfer technique
using atomic clocks
(Wenbin Shen, Wuhan Univ., China)
Coffee Break
Session 1B: Gravimetry and Gravity Networks (Room A)
Chair: Jean-Pierre Barriot, Xiaoli Deng
Field measurements of Absolute Gravity: current status, examples and perspectives
A First Traceable Gravimetric Calibration Line in the Swiss Alps
Urs Marti (Federal Office of Topography Swisstopo, Switzerland)
Russian-Finnish Comparison of five absolute gravimeters at four different sites in 2013
Jaakko Makine (Finnish Geodetic Institute, Finland)
On the estimation of diffraction and verticality corrections in absolute gravimetry
Vojtech Palinkas (Geodetic Observatory Pecny, Czech Republic)
Quality assessment of the new gravity control in Poland – first estimate
Jan Krynski (Ins. of Geodesy & Cartography, Poland)
What uses in today’s research for non-superconducting gravimeter observations in Earth Tides
modeling?
Jean-Pierre Barriot (Geodesy Observatory of Tahiti, Tahiti)
18:00-20:00
Ice Breaker
Wednesday 2nd July 2014
09:00-12:30
09:00-09:15
09:15-09:30
09:30-09:45
09:45-10:00
10:00-10:15
10:15-10:30
Session 2: Global Geopotential Models and Vertical Datum Unification (Room A)
Chair: Houze Hsu; Hussein Abd-Elmotaal
Gravity field from combination of GRACE and SLR data
Minkang Cheng (CSR-UT-Austin, USA)
EIGEN-6C4 – The latest combined global gravity field model including GOCE data up to degree
and order 1949 of GFZ Potsdam and GRGS Toulouse
Christoph Foerste (GFZ, Germany)
GGMplus (Global Gravity Model plus) – an ultra-high resolution near-global model of Earth’s
gravity field
Michael Kuhn (Curtin University, Australia)
Precise modeling of the static gravity field from GOCE data using the method of fundamental
solutions
Robert Cunderlik (Slovak University of Tech., Slovakia)
On the contribution of GOCE mission to modeling the gravimetric geoid: A case study - a
sub-region of East Africa and Central Europe
Jan Krynski (Ins. of Geodesy & Cartography, Poland)
Band-limited topographic mass distribution generates full-spectrum gravity field – gravity
forward modeling in the spectral and spatial domains revisited
Michael Kuhn (Curtin University, Australia)
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10:30-11:00
11:00-12:30
11:00-11:15
11:15-11:30
11:30-11:45
11:45-12:00
12:00-12:15
12:15-12:30
Coffee Break
Session 2B: Global Geopotential Models and Vertical Datum Unification (Room A)
Chair: Wenbin Shen, Michael Kuhn
Scientific Roadmap towards Height System Unification with GOCE
Thomas Gruber (TUM, Germany)
Adaption of the torus- and Rosborough approach to radial base functions
Wolfgang Keller (University Stuttgart, Germany)
Evaluation of GOCE/GRACE GGMs over Attika and Thessaloniki, Greece, and Wo
determination for height system unification
George S. Vergos (Aristotle Univ. of Thessaloniki, Greece)
Accurate Approximation of Vertical Gravity Gradient within the Earth’s External Gravity Field
Dongming Zhao (Zhenzhou Suv. & Mapping Inst. China)
5′×5′ global geoid: GG2014-re
Wenbin Shen (Wuhan Univ., China)
Ellipsoidal Effects, Modeling and Technique Refinements in High Accuracy Quasigeoid
Computations
Petr Holota (Res. Ins. of Gepdesy, Topography & Cartography, Czech Republic)
14:00-15:30
14:00-14:15
14:15-14:30
14:30-14:45
14:45-15:00
15:00-15:15
15:15-15:30
15:30-16:00
16:00-17:30
18:00-20:00
Session 3A: Local Geoid/Gravity Modeling (Room A)
Chair: Urs Marti, Jianliang Huang
Towards a unified vertical reference frame for south America in view of the GGOS specifications
Silvio R.C. de Freitas (UFPR, Brazil)
Analysis of distortions and offsets in Brazilian vertical network
Silvio De Freitas (Federal University of Parana, Brazil)
A detailed geoid model of Taiwan for height modernization, vertical datum connection and Lidar
mapping
Cheinway Hwang (National Chiao Tung Univ., Taiwan)
Retracking Jason-1 GM and Cryosat-2 LRM waveforms for modeling the regionally optimal
marine gravity field around Taiwan
Xiaoli Deng (University of Newcastle, Australia)
Establishment of the Gravity Database for the African Geoid
Hussein Abd-Elmotaal (Minia Univ., Egypt)
Gravity surveys and quasi-geoid model for South America
Denizar Blitzkow (Universidade de Sao Paulo (USP), Brazil)
Coffee Break
POSTER (SESSIONS 1, 2 and 3)
IGFS Meeting (Room B)
(Commission 2 Meeting)
Thursday 3rd July 2014
09:00-10:30
Session 3B: Local Geoid/Gravity Modeling (Room A)
Chair: Mirko Reguzzoni, Cheinway Hwang
09:00-09:15
Regional gravity field modeling using GOCE data: regularization issues
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Majid Naeimi (Leibniz Univ. of Hannover, Germany)
09:15-09:30
09:30-09:45
9:45-10:00
10:00-10:15
10:15-10:30
Factor analysis of the differences between the gravimetric geoid model and the observed geoid
undulations by using GPS/Leveling
Xiaopeng Li (NOAA, USA)
Glacial ice effect on the geoid
Jianliang Huang (Natural Resources Canada ,Canada)
New geoid of Greenland – a case study of terrain and ice effects, GOCE and local sea level data
Rene Forsberg (DTU, Denmark)
Estimating Geoid and Sea Surface Topography in the Mediterranean Sea
Hunting a 1 cm geoid in the land of fjords – Norway
Ove Christian Dahl Omang (Geodetic Institute, Norway)
Coffee Break
10:30-11:00
11:00-12:30
11:00-11:15
11:15-11:30
11:30-11:45
11:45-12:00
12:00-12:15
12:15-12:30
Session 4A: Satellite Gravimetry (Room A)
Chair: Jean-Michel Lemoine, Minkang Cheng
Progress on Satellite Technology for Gravity Exploration in China (INVITED)
Xiaomin Zhang (DFH Satellite Co. LTD, China)
Treatment of ocean tide aliasing in the context of a next generation gravity field mission
Michael Murbock (TUM, Germany)
Improvement of GOCE Level 1b Gradiometer Data Processing Over Magnetic Poles
E. Sinem Ince (York Univ., Canada)
An improved w-teststatistic Outlier detection method for GOCE gravity gradients
pre-processing
Yunlong Wu (Institute of Seismology, CEA, China)
Release 3 of the GRACE gravity solutions from CNES/GRGS
Jean-Michel Lemoine (CNES/GRGS, France)
Project of Space Advanced Gravity Measurements(SAGM) (INVITED)
Qi Kang (IMECH, CAS, China)
14:00-17:30
SOCIAL PROGRAM
18:00-20:00
Banquet (5th floor of Ronggang Restaurant, Room 527-529)
Friday 4th July 2014
09:00-10:30
9:00-9:15
9:15-9:30
9:30-9:45
Session 4B: Satellite Gravimetry (Room A)
Chair: Thomas Gruber, Xiaomin Zhang
Monthly gravity field model derived from GRACE Level1b data by modeling non-conservative
acceleration and attitude observation errors
Qiujie Chen (Tongji University, China)
Pendulum Orbit Configuration Analysis and Its Application in Earth Gravity Field Inversion
Hao Zhou (Wuhan Univ., China)
Gravity field processing and error assessment of future LL-SST type satellite missions using
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9:45-10:00
10:00-10:15
10:15-10:30
enhanced numerical precision.
Ilias Daras (TUM, Germany)
Next Generation Satellite Gravimetry Mission Study (NGGM-D)
Michael Murbock (TUM, Germany)
Progress of Space Electrostatic Accelerometer in HUST
Zebing Zhou (HUST, China)
Real-Time Data Simulation of Electrostatic Accelerometer for geodetic Satellite
Hongyin Li (HUST, China)
Coffee Break
10:30-11:00
11:00-12:30
11:00-11:15
11:15-11:30
11:30-11:45
11:45-12:00
12:00-12:15
12:15-12:30
Session 5A: Mass Movements in the Earth System (Room A)
Chair: Rene Forsberg, Zebing Zhou
The decomposition and interpretation of continental water storage changes derived from
GRACE
Hanjiang Wen (Chinese Academy of Surveying and Mapping, China)
Water storage and level variations in Lake Nasser (Africa) from satellite gravimetric and
Landsat data
Ayman A. Hassan (SHAO, CAS, China)
Hydrological impact on the discharge of Volta River basin of West Africa due to the water
impoundment by using satellite base data
Vagner Ferreira (Hohai University, China)
Inter-annual groundwater storage variations in North China from GRACE and ground
observations
Wei Feng (Ins. Geodesy Geophys., CAS, China)
Mass variations in the Siberian permafrost region based on new GRACE results and auxiliary
modeling
Akbar Shabanloui (Leibniz Univ. of Hannover, Germany)
Mass anomalies and trends in Russia from GRACE
Leonid Zotov (Sternberg Astronomical Institute, MSU, Russia)
14:00-15:30
14:00-14:15
14:15-14:30
14:30-14:45
14:45-15:00
15:00-15:15
Session 5B: Mass Movements in the Earth System (Room A)
Chair: Per Knudsen, David Salstein
Time-variable gravity signal in Greenland revealed by SWARM high-low Satellite-to-Satellite
Tracking
Zengtao Wang (Wuhan Univ., China)
Correlation analysis between the melting of the Eastern Tibetan Plateau glacier and the change
of Yangtze River water storage
Nengfang Chao (Wuhan Univ., China)
Mass Trends in Antarctica with adapted filtering from GRACE gravity field time series
Alexander Horvath (TUM, Germany)
Land-ocean leakage effects on Glacier mass loss in Greenland estimated from GRACE
Fang Zou (SHAO, CAS, China)
Feasibility and significance of a GRACE ensemble solution for Antarctic mass trend estimation
Alexander Horvath (TUM, Germany)
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15:15-15:30
Uncertainty of ice sheet contributions to global sea level change from GRACE in 2003-2012
Guiping Feng (SHAO, CAS, China)
Coffee Break
15:30-16:00
16:00-17:30
16:00-16:15
16:15-16:30
16:30-16:45
16:45-17:00
17:00-17:15
17:15-17:30
Session 6A: Solid Earth Investigations (Room A)
Chair: Franz Barthelmes, Robert Tenzer
Errors of geocenter motion estimates from global GPS observations
Xinggang Zhang (SHAO, CAS, China)
Consistent Estimates of the Dynamic Figure Parameters of the Stratified Earth
Wei Chen (Wuhan Univ., China)
Test method for determining the anomalous internal structure of terrestrial planets, space
research abased on the example of the Earth
Nadezhda Chujkova (Sternberg Astronomical Institute, MSU, Russia)
Post-glacial rebound signal observed with repeated absolute gravimetry in Finland
Mirjam Bilker-Koivula (Finnish Geodetic Institute, Finland)
Role of Glacial Isostatic Adjustment Process in Present-Day Sea-Level Budget Closure
Zhenwei Huang (Chinese Academy of Surveying and Mapping, China)
Spectral and spatial characteristics of the refined CRUST1.0 gravity field
Robert Tenzer (Wuhan Univ., China)
Saturday 5th July 2014
09:00-10:15
POSTER (SESSIONS 4, 5 and 6)
10:15-10:30
Coffee Break
10:30-12:00
10:30-10:45
10:45-11:00
11:00-11:15
11:15-11:30
11:30-11:45
11:45-12:00
12:00-12:15
12:15:12:30
Session 6B: Solid Earth Investigations (Room A)
Chair: Petr Holota, George S. Vergos
Spectral harmonic analysis of global crustal structure
Wenjing Chen (Wuhan Univ., China)
Global gravimetric crustal thickness based on uniform and variable models of the crust-mantle
density interface
Robert Tenzer (Wuhan Univ., China)
Looking for sedimentary basins using global gravity field and crustal models
Stefano Colpani (DTU, Denmark)
Analysis of earthquake Patterns in Iran based on the deflection of vertical components of the
EGM2008 global geoid model
Ramin Kiamehr (Zanjan University, Iran)
Study on Density structure characters of Xiaojiang fault system
Guangliang Yang (UCAS, China)
Reevaluation of the Lithospheric Effective Elastic Thickness in Western Pacific
Minzhang Hu (Institute of Seismology, CEA, China)
Determining the hydrological excitation of polar motion from GRACE gravity solutions
David Salstein (Atmospheric and Environmental Research, USA)
Closing Session
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3. Posters
Name
Affiliation
Title
POSTER (SESSIONS 1, 2 and 3) on 2 July 2014 (16:00-17:30)
Jan Krynski
Jaakko Makine
Vojtech
Palinkas
Shaokun Cai
Haibing Li
Theresa
Damiani
Jack
McCubbine
Ole Baltazar
Andersen
George S.
Vergos
Laura Sanchez
Ins. of Geodesy &
Cartography, Poland
Finnish Geodetic Institute,
Finland
Geodetic Observatory
Pecny, Czech Republic
NUDT, China
Beijing Institute of
Aerospace Control Devices,
China
Review and future prospects of inertial gravimetry and
gradiometry systems
NOAA, USA
Analysis of Aircraft Dynamics from Seven Years of
Aerogravity Data Collection
Victoria Univ. of
Wellington, New Zealand
Airborne gravity across New Zealand
DTU Space, Denmark
Aristotle Univ. of
Thessaloniki, Greece
DGFI, Munich, Germany
George S.
Vergos
Mohsen
Romeshkan
Siavash
Ghelichkhan
Aristotle Univ. of
Thessaloniki, Greece
Nevin Betul
Avsar
Bulent Ecevit University,
Turkey
Mehmet Simav
Cheinway
Hwang
Session 1
The use of the A10-020 absolute gravimeter for the
modernization of gravity control in Poland
The effect of helium emissions by a superconducting
gravimeter on the rubidium clocks of absolute gravimeters
SGNoise - a tool for the ambient noise level analysis at
superconducting gravimeter stations
An airborne gravimetry comparison of stable platform
gravimeter LCR and strapdown airborne gravimeter
SGA-WZ
K.N.Toosi Univ. Tech., Iran
Technical University of
Munich, Germany
General Command of
Mapping, Turkey
National Chiao Tung Univ.,
Taiwan
Session 2
The Global Gravity Field Model (DTU13) and evaluation
in the Arctic Ocean
Wavelet
multi-resolution
analysis
of
recent
GOCE/GRACE GGMs
Towards a new best estimate for the conventional value of
W0
Evaluation of GOCE/GRACE GGMs over Argentina with
GPS/Leveling and gravity anomaly data
Study and investigation for Behaviours of isotropic parts
of the modified kernel integral estimators
Estimating the time evolution of the geoid
Evaluation of GOCE-based Global Geopotential
Models versus EGM2008 and GPS/Levelling data in
Turkey
Session 3
Software Development for Relative Gravimetry towards
Turkish Height System Modernization
New gravity grid and geoid model of Tahiti from airborne
and terrestrial gravity surveys
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Hussein
Abd-Elmotaal
Hussein
Abd-Elmotaal
Abelardo
Bethencourt
Gabriel
Guimaraes
Ove Christian
Dahl Omang
Jan Krynski
Lajos Volgyesi
Minia Univ., Egypt
Minia Univ., Egypt
Polytechnic University of
Madrid, Spain
Federal Univ. of Uberlandia,
Brazil
Combination between Altimetry and Shipborne Gravity
Data for Africa
Egyptian Geoid using Best Estimated Response of the
Earth's Crust due to Topographic Loads
A precise regional Geoid for the Valley of the Cauca
River, Colombia
Quasi-geoid model in the State of São Paulo
Geodetic Institute, Norway
Hunting a 1 cm geoid in the land of fjords – Norway
Ins. of Geodesy &
Cartography, Poland
Budapest Univ. of Tech. and
Economics, Hungary
A new gravimetric geoid model for the area of Sudan using
the least squares collocation and a GOCE-based GGM
Renaissance of the torsion balance measurements
POSTER (SESSIONS 4, 5 and 6) on 5 July 2014 (11:00-12:30)
Mirko
Reguzzoni
Siavash
Iran-Pour
Michael
Murboeck
Politecnico di Milano, Italy
University Stuttgart,
Germany
Tech. Univ. Munich,
Germany
Xuyang Hou
Beijing Univ. of Technology,
China
Ole Baltazar
Andersen
DTU Space, Denmark
Per Knudsen
DTU Space, Denmark
Jiandi Fang
Wuhan Univ., China
Ira Mutiara
Anjasmara
Sepuluh Nopember Inst. of
Tech., Indonesia
Robert Tenzer
Wuhan Univ., China
Robert Tenzer
Wuhan Univ., China
Daniele
Sampietro
Xiang Gu
Geomatics Research &
Development SRL, Italy
Wuhan Univ., China
Session 4
GOCE data as grids of gravity gradients at satellite
altitude
Genetic-algorithm based search strategy for optimal
scenarios of future dual-pair gravity satellite missions
De-correlation of two low-low Satellite-to-Satellite
tracking pairs according to temporal aliasing
Research on precisely matching methods of the
accelerometers applied to rotary accelerometer gravity
gradiometer
The DTU13 MSS (Mean Sea Surface) and MDT (Mean
Dynamic Topography)
from 20 years of satellite
altimetry
GOCE User Toolbox and Tutorial
Session 5
Evaluation of groundwater storage changes in Horqin
Sandy Land (China) by using GRACE
Validating methods to infer mass changes from satellite
gravity measurements using Synthetic Earth Gravity
Modeling
Session 6
Sub-crustal stress induced by mantle convection from
gravity data
Effect of the rock equivalent topography on the Moho
geometry
Bayesian estimation of geological provinces from GOCE
data
Crustal stress in Taiwan
14
4. Content
A.Bethencourt, Jhon Jairo Barona, Olga Lucia Vaquero; A precise regional Geoid for the Valley of the Cauca River,
Colombia ............................................................................................................................................................................ 20
A.C. Peidou , G.S. Vergos; Wavelet multi-resolution analysis of recent GOCE/GRACE GGMs ....................................... 20
Akbar Shabanloui , Jürgen Müller; Mass variations in the Siberian permafrost region based on new GRACE results and
auxiliary modeling .............................................................................................................................................................. 21
Alexander Horvath, Martin Horwath, Roland Pail; Feasibility and significance of a GRACE ensemble solution for
Antarctic mass trend estimation .......................................................................................................................................... 21
Alexander Horvath, Martin Horwath, Roland Pail, Ingo Sasgen; Mass Trends in Antarctica with adapted filtering from
GRACE gravity field time series ........................................................................................................................................ 22
ANDREA GALUDHT SANTACRUZ JARAMILLO, SÍLVIO ROGÉRIO CORREIA DE FREITAS, LAURA SÁNCHEZ;
TOWARDS A UNIFIED VERTICAL REFERENCE FRAME FOR SOUTH AMERICA IN VIEW OF THE GGOS
SPECIFICATIONS ............................................................................................................................................................. 22
Ayman A. Hassan, Shuanggen Jin; Water storage and level variations in Lake Nasser (Africa) from satellite gravimetric and
Landsat data ........................................................................................................................................................................ 23
C. Hwang, J.P. Barriot, H.C. Shih, et al; New gravity grid and geoid model of Tahiti from airborne and terrestrial gravity
surveys ................................................................................................................................................................................ 24
C.N. Tocho, G.S. Vergos; Evaluation of GOCE/GRACE GGMs over Argentina with GPS/Leveling and gravity anomaly
data ..................................................................................................................................................................................... 24
Ch. Förste, F. Flechtner, Ch. Dahle, et al; EIGEN-6C4 – The latest combined global gravity field model including GOCE
data up to degree and order 1949 of GFZ Potsdam and GRGS Toulouse ........................................................................... 25
Cheinway Hwang, Hung-Jui Hsu, Ming Yang, et al; A detailed geoid model of Taiwan for height modernization, vertical
datum connection and Lidar mapping ................................................................................................................................. 26
Christian Hirt, Michael Kuhn; Band-limited topographic mass distribution generates full-spectrum gravity field – gravity
forward modelling in the spectral and spatial domains revisited ........................................................................................ 26
Christian Hirt, Michael Kuhn, Sten Claessens, et al; GGMplus (Global Gravity Model plus) – an ultra-high resolution
near-global model of Earth’s gravity field .......................................................................................................................... 27
D. R. Roman, X. Li, Y.M. Wang, et al; Factor analysis of the differences between the gravimetric geoid model and the
observed geoid undulations by using GPS/Leveling .......................................................................................................... 28
Daniele Sampietro, Mirko Reguzzoni; Bayesian estimation of geological provinces from GOCE data ............................. 28
David Becker, Matthias Becker, Stefan Leinen, et al; Improving estimability in strapdown airborne vector gravimetry ... 29
Denizar Blitzkow, Ana Cristina Oliveira Cancoro de Matos, Daniel Silva Costa, et al; Gravity surveys and quasi-geoid
model for South America .................................................................................................................................................... 29
Dongming Zhao, Qingbin Wang, Huan Bao, et al; Accurate Approximation of Vertical Gravity Gradient within the Earth’s
External Gravity Field ........................................................................................................................................................ 30
E. S. Ince , S. Pagiatakis; Improvement of GOCE Level 1b Gradiometer Data Processing Over Magnetic Poles ............ 31
F. Barthelmes, W. Köhler; The ICGEM: an IAG Gravity Field Service ............................................................................. 31
Fang Zou, Shuanggen Jin; Land-ocean leakage effects on Glacier mass loss estimate from GRACE in Greenland ......... 32
G.S. Vergos, V.D. Andritsanos, V.N. Grigoriadis, et al; Evaluation of GOCE/GRACE GGMs over Attika and Thessaloniki,
Greece, and Wo determination for height system unification ............................................................................................. 32
Gabriel do Nascimento Guimarães, Denizar Blitzkow, Ana Cristina Oliveira Cancoro de Matos; Quasi-geoid model in the
15
State of São Paulo ............................................................................................................................................................... 33
Guangliang Yang, Chongyang Shen, Hongbo Tan, et al; Study on Density structure chatacters of Xiaojiang fault system
............................................................................................................................................................................................ 34
Guiping Feng, Shuanggen Jin; Uncertainty of ice sheet contributions to global sea level change from GRACE in
2003-2012 ........................................................................................................................................................................... 34
H. Zhou, Z. C. Luo, B. Zhong, et al; Pendulum Orbit Configuration Analysis and Its Application in Earth Gravity Field
Inversion ............................................................................................................................................................................. 35
Haibing Li, Michael G. Sideris, Dongming Li,et al; Review and future prospects of inertial gravimetry and gradiometry
systems................................................................................................................................................................................ 35
Hanjiang Wen, Zhenwei Huang, Youlei Wang,et al; The decomposition and interpretation of continental water storage
changes derived from GRACE ........................................................................................................................................... 36
Hongyin Li, Kun Wang, Shaobo Qu, et al; Real-Time Data Simulation of Electrostatic Accelerometer for geodetic Satellite
............................................................................................................................................................................................ 36
Hussein A. Abd-Elmotaal; Egyptian Geoid using Best Estimated Response of the Earth's Crust due to Topographic Loads
............................................................................................................................................................................................ 37
Hussein A. Abd-Elmotaal, Atef Makhloof; Combination between Altimetry and Shipborne Gravity Data for Africa ........ 38
Hussein A. Abd-Elmotaal, Kurt Seitz, Norbert Kühtreiber, et al; Establishment of the Gravity Database for the African
Geoid .................................................................................................................................................................................. 38
I.M. Anjasmara, M. Kuhn, J. Awange; Validating methods to infer mass changes from satellite gravity measurements using
Synthetic Earth Gravity Modelling ..................................................................................................................................... 39
I.N. Tziavos, G.S. Vergos , V.N. Grigoriadis; The development of a new gravimetric geoid model for Greece: GGeoid2014
............................................................................................................................................................................................ 39
Ilias Daras, Roland Pail, Michael Murböck; Gravity field processing and error assessment of future LL-SST type satellite
missions using enhanced numerical precision .................................................................................................................... 40
J. Huang, M. Véronneau, J. A. Dowdeswell,et al; Glacial ice effect on the geoid .............................................................. 41
J. Mäkinen, R.A. Sermyagin, I.A. Oshchepkov, et al; Russian-Finnish Comparison of five absolute gravimeters at four
different sites in 2013 ......................................................................................................................................................... 41
Jaakko Mäkinen, Heikki Virtanen, Mirjam Bilker-Koivula, et al; The effect of helium emissions by a superconducting
gravimeter on the rubidium clocks of absolute gravimeters ............................................................................................... 42
Jack McCubbine, Euan Smith, Matt Amos, et al; Airborne gravity across New Zealand; .................................................. 42
Jan Krynski, Przemyslaw Dykowski; The use of the A10-020 absolute gravimeter for the modernization of gravity control
in Poland ............................................................................................................................................................................. 42
Jan Krynski, Przemyslaw Dykowski; Release 3 of the GRACE gravity solutions from CNES/GRGS .............................. 43
Jean-Pierre Barriot, Bernard Ducarme; What uses in today’s research for non-superconducting gravimeter observations in
Earth Tides modeling? ........................................................................................................................................................ 44
Jian-Di FENG, Zheng-Tao WANG, Wei-Ping Jiang, et al; Evaluation of groundwater storage changes in Horqin Sandy Land
(China) by using GRACE ................................................................................................................................................... 44
L. Sánchez, R. Čunderlík, N. Dayoub,et al; Towards a new best estimate for the conventional value of W0 .................... 45
L.Volgyesi; Renaissance of the torsion balance measurements ........................................................................................... 45
Lei Zhao, Kaidong Zhang, Meiping Wu, Rene Forsberg, Arne Vestergaard Olesen; An Airborne Gravimetry Test of
SGA-WZ in Greenland ....................................................................................................................................................... 46
M. Murböck, R. Pail; De-correlation of two low-low Satellite-to-Satellite tracking pairs according to temporal aliasing 46
M. Murböck, Th. Gruber, M. Baldesarra; Next Generation Satellite Gravimetry Mission Study (NGGM-D) .................. 47
Majid Naeimi, Jakob Flury; Regional gravity field modeling using GOCE data: regularization issues ............................ 47
16
Matt Amos, Jack McCubbine, Rachelle Winefield, et al; Airborne gravity for an improved New Zealand quasigeoid...... 48
Mehdi Eshagh, Robert Tenzer; Sub-crustal stress induced by mantle convection from gravity data ................................. 48
Mehmet Simav, Hasan Yildiz; Software Development for Relative Gravimetry towards Turkish Height System
Modernization ..................................................................................................................................................................... 49
Minkang Cheng ; Gravity field from combination of GRACE and SLR data .................................................................... 49
Mirjam Bilker-Koivula, Jaakko Mäkinen, Hannu Ruotsalainen; Post-glacial rebound signal observed with repeated
absolute gravimetry in Finland ........................................................................................................................................... 50
Mirko Reguzzoni, Andrea Gatti, Federica Migliaccio, et al; GOCE data as grids of gravity gradients at satellite altitude 50
Mirko Reguzzoni, Giovanna Sona; The International Geoid Service: present status and future perspectives .................... 51
Mohammad Bagherbandi , Lars E. Sjöberg; Viscosity of the mantle inferred from land uplift rate and three reduced gravity
field models in Fennoscandia ............................................................................................................................................. 52
Mohammad Bagherbandi, Lars E Sjöberg, Majid Abrehdary; Effect of the rock equivalent topography on the Moho
geometry ............................................................................................................................................................................. 52
Mohsen Romeshkani, Sahar Ebadi; Study and investigation for Behaviours of isotropic parts of the modified kernel
integral estimators ............................................................................................................................................................... 53
NengFang CHAO , ZhengTao WANG; Correlation analysis between the melting of the Eastern Tibetan Plateau glacier and
the change of Yangtze River water storage ......................................................................................................................... 53
Nevin Betul Avsar, Bihter Erol, Senol Hakan Kutoglu; Evaluation of GOCE-based Global Geopotential Models versus
EGM2008 and GPS/Levelling data in Turkey .................................................................................................................... 54
Ole Andersen, Lars Stenseng , Per Knudsen; The DTU13 MSS (Mean Sea Surface) and MDT (Mean Dynamic Topography)
from 20 years of satellite altimetry ..................................................................................................................................... 54
Ole Baltazar Andersen, P. Knudsen, L. Stenseng, et al; The Global Gravity Field Model (DTU13) and evaluation in the
Arctic Ocean ....................................................................................................................................................................... 55
Otakar Nesvadba, Petr Holota; Ellipsoidal Effects, Modelling and Technique Refinements in High Accuracy Quasigeoid
Computations ...................................................................................................................................................................... 55
Ove Christian Dahl Omang , Dagny Iren Lysaker; Hunting a 1 cm geoid in the land of fjords-Norway........................... 56
Per Knudsen, Jerome Benveniste, Team GUT; GOCE User Toolbox and Tutorial ............................................................. 56
Przemyslaw Dykowski, Jan Krynski; Quality assessment of the new gravity control in Poland – first estimate ................ 57
Q. KANG, W.R, HU; Project of Space Advanced Gravity Measurements(SAGM) ............................................................. 58
Qiujie Chen, Yunzhong Shen, Houze Hsu, et al; Monthly gravity field model derived from GRACE Level1b data by
modeling non-conservative acceleration and attitude observation errors ........................................................................... 58
R. Barzaghi, A. Albertella, F. Barthelmes, et al; Testing airborne gravity data in the large-scale area of Italy and adjacent
seas ..................................................................................................................................................................................... 59
R.Barzaghi, A. Albertella, N. E. Cazzaniga, et al; Estimating Geoid and Sea Surface Topography in the Mediterranean Sea
............................................................................................................................................................................................ 59
R.Kiamehr; ANALUIS OF EARTHQUAKES PATTERNS IN IRAN BASED ON THE DEFELECTION OF VERTICAL
COMPONENTS OF THE EGM2008 GLOBAL GEOID MODEL ................................................................................... 60
R. Pail, M. Murböck, J. Honecker, et al; Treatment of ocean tide aliasing in the context of a next generation gravity field
mission ................................................................................................................................................................................ 61
Rene Forsberg, Arne Vestergaard Olesen, Jens Emil Nielsen; Airborne gravimetry for geoid and GOCE ........................ 61
Rene Forsberg, Tim Jensen; New geoid of Greenland – a case study of terrain and ice effects, GOCE and local sea level
data ..................................................................................................................................................................................... 62
Róbert Čunderlík; Precise modelling of the static gravity field from GOCE data using the method of fundamental solutions
............................................................................................................................................................................................ 62
17
Robert Tenzer, Wenjin Chen, Dimitrios Tsoulis, et al; Spectral and spatial characteristics of the refined CRUST1.0 gravity
field ..................................................................................................................................................................................... 63
Robert Tenzer, Wenjin Chen, Shuanggen Jin; Global gravimetric crustal thickness based on uniform and variable models of
the crust-mantle density interface ....................................................................................................................................... 64
S. Bonvalot, F. Reinquin, G. Balmino, et al; The International Gravimetric Bureau (BGI) : tasks and objectives ............. 64
S. Bonvalot, G. Gabalda , T. Gattacceca , et al; Field measurements of Absolute Gravity: current status, examples and
perspectives ........................................................................................................................................................................ 65
Shaokun Cai, Meiping Wu, Kaidong Zhang, et al; An airborne gravimetry comparison of stable platform gravimeter LCR
and strapdown airborne gravimeter SGA-WZ .................................................................................................................... 65
Siavash Ghelichkhan; Estimating the time evolution of the geoid ..................................................................................... 66
Siavash Iran-Pour, Tilo Reubelt, Matthias Weigelt, et al; Genetic-algorithm based search strategy for optimal scenarios of
future dual-pair gravity satellite missions ........................................................................................................................... 66
SÍLVIO R. C. DE FREITAS, VAGNER G. FERREIRA,HENRY D. MONTECINO, et al; ANALYSIS OF DISTORTIONS
AND OFFSETS IN BRAZILIAN VERTICAL NETWORK ............................................................................................. 67
Stefano Colpani ,Gabriel Strykowski; Looking for sedimentary basins using global gravity field and crustal models ...... 68
Th. Gruber, R. Rummel, HPF Team; GOCE Gravity Field Models – Overview and Performance Analysis ...................... 68
Th. Gruber, R. Rummel, M. Sideris, et al; Scientific Roadmap towards Height System Unification with GOCE ............. 69
Theresa M. Damiani, Vicki A. Childers, Sandra A. Preaux, et al; Analysis of Aircraft Dynamics from Seven Years of
AerogravityData Collection ................................................................................................................................................ 69
Urs Marti, Henri Baumann, Beat Bürki, et al; A First Traceable Gravimetric Calibration Line in the Swiss Alps ........... 70
Vagner G. Ferreitra, Ehsan Forootan, Joseph L. Awange, et al; Hydrological impact on the discharge of Volta River basin
of West Africa due to the water impoundment by using satellite base data ........................................................................ 71
Vojtech Pálinkáš, Miloš Vaľko; SGNoise - a tool for the ambient noise level analysis at superconducting gravimeter stations
............................................................................................................................................................................................ 71
Vojtech Pálinkáš, Petr Balling, Petr Křen, et al; On the estimation of diffraction and verticality corrections in absolute
gravimetry ........................................................................................................................................................................... 72
W. Keller, R. J. You; Adaption of the torus- and Rosborough approach to radial base functions ........................................ 73
Walyeldeen Godah, Jan Krynski; A new gravimetric geoid model for the area of Sudan using the least squares collocation
and a GOCE-based GGM ................................................................................................................................................... 73
Walyeldeen Godah, Jan Krynski, Malgorzata Szelachowska; On the contribution of GOCE mission to modelling the
gravimetric geoid: A case study - a sub-region of East Africa and Central Europe ............................................................ 74
Wei Chen, JianCheng Li, Jim Ray, et al; Consistent Estimates of the Dynamic Figure Parameters of the Stratified Earth 74
Wei Feng, Min Zhong, Hou-ze Xu; Inter-annual groundwater storage variations in North China from GRACE and ground
observations ........................................................................................................................................................................ 75
WenBin Shen, Jiancheng Han; 5′×5′ global geoid: GG2014-re .......................................................................................... 75
Wenjin Chen, Robert Tenzer; Spectral harmonic analysis of global crustal structure ......................................................... 76
Xiang Gu, Robert Tenzer , Cheinway Hwang; Crustal stress in Taiwan ............................................................................. 76
Xiaoli Deng, Cheinway Hwang, Yung-Sheng Cheng; Retracking Jason-1 GM and Cryosat-2 LRM waveforms for
modelling the regionally optimal marine gravity field around Taiwan ............................................................................... 77
Xinggang Zhang, Shuanggen Jin; Errors of geocenter motion estimates from global GPS observations .......................... 77
Xuyang HOU, Haibing LI, Hui YANG, et al; Research on precisely matching methods of the accelerometers applied to
rotary accelerometer gravity gradiometer ........................................................................................................................... 78
Yunlong WU, Hui Li, Kaixuan Kang, et al; An improved w-teststatistic Outlier detection method for GOCE gravity
gradients pre-processing ..................................................................................................................................................... 78
18
Z.B. Zhou, Y.Z. Bai, M. Hu, et al; Progress of Space Electrostatic Accelerometer in HUST .............................................. 78
Zheng-Tao WANG, Neng-Fang CHAO; Time-variable gravity signal in Greenland revealed by SWARM high-low
Satellite-to-Satellite Tracking ............................................................................................................................................. 79
Zhenwei Huang, Hanjiang Wen, C.K. Shum; Role of Glacial Isostatic Adjustment Process in Present-Day Sea-Level
Budget Closure ................................................................................................................................................................... 80
ZiYu Shen, WenBin Shen; An approach for determining the geopotential based upon coaxial cable time transfer technique
using atomic clocks............................................................................................................................................................. 80
N. A. Chujkova, L. P. Nasonova, and T. G. Maximova, Test method for determining the anomalous internal structure of
terrestrial planets, space research abased on the example of the Earth……………………………………………………80
L. Zotov, C.K. Shum, Natalya Frolova, Mass anomalies and trends over Russia from GRACE…………………………802
19
5. Abstracts
A precise regional Geoid for the Valley of the Cauca River, Colombia
A.Bethencourt1, Jhon Jairo Barona2, Olga Lucia Vaquero2
1
Polytechnic University of Madrid
2
Del Valle – Colombia University
Abstract: In this work we carried out a precise geoid for the Cauca Valley in its low course. With data coming from
aerogravimetry, our own measurements on the field and those obtained from the official agency IGAC, we have
applied the classical second method of Helmert condensation with the remove – restore technique. We also made a
geometric geoid through the valley from a previous leveling line. This geometry geoid was used to calibrate the
precision of the gravimetric geoid. We have also tested different Stokesian nucleus, different integrations radius and
different combinations of coefficients from Global Geopotential Models, etc…with the purpose of obtaining the
best gravimetric geoid in the region.
Wavelet multi-resolution analysis of recent GOCE/GRACE GGMs
A.C. Peidou and G.S. Vergos
Department of Geodesy and Surveying, School of Rural and Surveying Engineering, Aristotle University of Thessaloniki, Greece,
[email protected]
Abstract: Monitoring and understanding of gravity fields’ parameters at various spatial scales has been the focus of
many studies during the past decades. The realization of the GRACE/GOCE missions offer new opportunities for
gravity field approximation with higher accuracy at the medium wavebands, while wavelets (WL) provide powerful
gravity field analysis tools in the frequency domain. This work focuses on the spectral analysis of GOCE,
GOCE/GRACE and combined Global Geopotential Models through wavelet decomposition, filtering and
reconstruction in order to improve their performance as to their spectral content in the higher bands of the spectrum.
Moreover they are employed in order to investigate the coherence and the correlation between GGMs gravity
information and topography. The GGMs evaluated refer to the latest DIR-R4, TIM-R4 and GOCO03s models,
which are compared with local GPS/Leveling geoid heights and gravity anomalies, while EGM2008 is used as a
reference. Through a WL-based multi-resolution analysis, gravity anomalies and geoid heights are analyzed to
derive their approximation and detail coefficients for various levels of decomposition, which correspond to
different spatial scales. The content and signal power of each level of decomposition is analyzed to conclude on the
amount and quality of signal power that GOCE/GRACE GGMs represent compared to EGM2008, especially in the
targeted waveband up to 110-150 km. Moreover, various types of low-pass and thresholding denoising filters are
investigated to remove high-frequency information from the low resolution GOCE models and adjust the WL
reconstruction, respectively. The model synthesis that follows, through coefficient reconstruction, aims at the
generation of new synthesized GGMs, where both GOCE, GRACE and EGM2008 information is used. Validation
of the synthesized combined GGMs with available GPS/Leveling geoid heights and terrestrial gravity anomalies is
performed, to further assess the improvement brought by the WL analysis. Finally, the investigation of the GGMs’
20
and Topography’s correlation and coherence is accomplished through the spectral content analysis of each level, in
order to conclude on the amount of the gravity signal that GOCE/GRACE GGMs manage to represent w.r.t.
EGM2008.
Mass variations in the Siberian permafrost region based on new GRACE results
and auxiliary modeling
Akbar Shabanloui and Jürgen Müller
Institute of Geodesy, University of Hannover, Germany
([email protected], mü[email protected]/ Phone: +49-511-7625149)
Abstract: GRACE (Gravity Recovery and Climate Experiment) determines the integral mass variations in the Earth
system with different spatial-temporal resolution. These mass variations should be adequately separated for better
understanding of the single signal contributions. In Siberia, the temporal mass variations are related to hydrological
processes including thawing of huge permafrost layers. The permafrost layers with different thicknesses cover
about 80% of Siberia. Therefore these frozen sheets play an important role for sea level rise and the hydrological
water cycle. In this study, the integral mass variations in Siberia are precisely estimated based on the new release of
GRACE from GFZ (RL05a). On the other hand, various hydrological contributions (lake level variation, river
runoff, etc.) can be estimated from different models and specific data. Here, mass variations in the Siberian
permafrost region based on GRACE results and different hydrological models/data will be jointly investigated.
Feasibility and significance of a GRACE ensemble solution for
Antarctic mass trend estimation
Alexander Horvath1, Martin Horwath2, Roland Pail1
1
Technische Universität München, IAPG, Arcisstr. 21, 80333 München, Germany, [email protected]
2
Technische Universität Dresden, IPG, Helmholtzstr. 10, 01069 Dresden, Germany
Abstract: The feasibility and significance of an ensemble solution made up from different release 05 (RL05)
solutions is an interesting question asking for the best way how to combine different time series, based on which
criteria, and to assess the potential benefit of such an ensemble solution with respect to the official or standard
solutions. The first step for such an approach is a comprehensive analysis of the available RL05 time series. Our
focus was set on the official and some experimental GFZ, CSR, and JPL series available up to the degrees 60, 90,
and 96. We compare these different time series with respect to their signal and noise content and analyze them on
global and regional scale. For the regional scale our special interest is paid on Antarctica and on revealing polar
signals such as ice mass trends. Answering the question for the most suitable degree of expansion, our analysis
suggests using gravity field models up to degree 90 or even higher as such models maybe become available in the
future. Previous investigations have shown that destriping affects the different solutions in different ways. We
demonstrate this effect on the before mentioned regional test case Antarctica. The noise level of the solutions by
CSR and GFZ are more similar after destriping than before destriping. The destriping process was optimized to best
balance between the two goals noise of reduction and signal corruption in the Antarctic region. A full stochastic
21
model is formulated for the whole trend determination process to better describe the trend estimation process. This
all helps for answering the question regarding the significance of the ensemble solution.
Mass Trends in Antarctica with adapted filtering from
GRACE gravity field time series
Alexander Horvath1, Martin Horwath2, Roland Pail 1, Ingo Sasgen 3
1
Technische Universität München, IAPG, Arcisstr. 21, 80333 München, Germany, [email protected]
2
Technische Universität Dresden, IPG, Helmholtzstr. 10, 01069 Dresden, Germany
3
GFZ German Research Centre for Geosciences, Department of Geodesy and Remote Sensing, 14473 Potsdam, Germany
Abstract: Aiming for an as accurate as possible estimation of mass trends in Antarctica out of GRACE Release 05
(RL05) monthly gravity field solutions calls for a number of tasks. Motivated by the need for a new and more
accurate trend estimate, this work serves as contribution for a new glacial isostatic adjustment model (GIA) within
the ESA STSE REGINA project.
The first step in this approach is an extensive analysis of the available GRACE gravity field solution series in terms
of signal and noise content and temporal evolution on global and regional scale. We put our focus on official and
experimental time series from GFZ, CSR, and JPL expanded up to degrees 60, 90, and 96. For revealing also basin
scale signals we decided to use time series expanded up to degree 90.
Proper reduction of correlated errors is a crucial step towards trend estimation. For this purpose we set up a tailored
Swenson & Wahr type filter for the specific needs in the Antarctic region such as polar location and orientation of
geographic features. The filter is designed to best balance between the two opposing goals of signal corruption and
destriping or noise reduction. To better understand the impact of applying such a filter, we perform full error
propagation for the filtering process as well as throughout the whole trend estimation process. Nonlinear mass
changes induced by surface mass variations (SMB) are accounted for by using modelled simulated SMB variations.
To give a single number for the mass trend in Antarctica or a single basin, integration kernels are needed as last step
to convert grids into mass changes per region of interest. The proper design of such a kernel is essential to avoid
under-/overestimation. We improve upon previous work by performing a formalized tailoring of the sensitivity
kernel, balancing leakage effect and propagation of GRACE model errors. We demonstrate this process for the
Antarctic Peninsula as a regional test case.
TOWARDS A UNIFIED VERTICAL REFERENCE FRAME FOR SOUTH
AMERICA IN VIEW OF THE GGOS SPECIFICATIONS
ANDREA GALUDHT SANTACRUZ JARAMILLO 1, SÍLVIO ROGÉRIO CORREIA DE FREITAS 1,
LAURA SÁNCHEZ 2
1
Universidade Federal do Paraná– UFPR Setor de Ciências da Terra Departamento de Geomática, Curitiba PR
[email protected], [email protected]
2
Deutsches Geodätisches Forschungsinstitut – DGFI Munich, Germany, [email protected]
22
Abstract: One of the most important objectives of SIRGAS (Sistema de Referencia Geocéntrico para las Américas)
is to establish a unified gravity-filed related vertical reference system that meets the GGOS requirements on
long-term stability and homogenous high-reliability. This implies the unification of the local height systems
existing in the region and their precise integration into a Global Vertical Reference System (GVRS). For that,
different strategies based on the combination of classical height data, GNSS positioning and satellite gravity
modelling to solve the Gravity Boundary Value Problem (GBVP) are being evaluated worldwide; however, most of
them are not applicable in South America because the disparity existing between the local height systems is only
partially known. According to this, the first step in this work is the survey of an inventory and the consequent
implementation of meta-data describing the characteristics of the national vertical and gravimetric networks. This
allows the identification of the different standards and specifications applied for the establishment of those
networks; in special, the local reference levels, the individual realization epochs, the omission of gravity effects on
levelling, and the no consideration of geodynamic aspects affecting their temporal evolution. Based on these results,
a roadmap describing the activities required to standardize the classical height data is outlined; having as a main
goal the minimization of those uncertainties produced by non-measuring errors, like omissions or the use of
different approximations in the levelling processing. The last part of this study concentrates on identifying the most
appropriate approach to be applicable for the unification of the local datums in South America. It is expected that
this methodology can be extended to Central America and the Caribbean, as well as to those regions where the
geodetic data present similar characteristics.
Water storage and level variations in Lake Nasser (Africa) from satellite
gravimetric and Landsat data
Ayman A. Hassan1, 2, Shuanggen Jin1
Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
University of Chinese Academy of Sciences, Beijing 10049, China
Abstract: Accurately monitoring water storage and lake level variations in river basins and reservoirs is very
difficult due to lack of comprehensive in-suit observations, particularly in Africa. The Lake Nasser in southern
Egypt is one of the largest man-made freshwater reservoirs in the world. Water level in the lake fluctuates
seasonally and secularly according to the receiving net water as well as the operations of the High Dam. Lake
Nasser is invaluable for Egypt as it represents a large reservoir for the country’s freshwater resources. Precisely
monitoring water storage variations in the lake is crucial for better management of Egypt’s water resources. With
the launch of the Gravity Recovery and Climate Experiment (GRACE) mission since 2002, it provides a unique
chance to estimate terrestrial water storage (TWS) changes. In addition, the Landsat satellites also provide unique
historical continuous space-based record of Earth’s continents and surrounding coastal regions since 1972. In this
paper, water storage and level variations in Lake Nasser are investigated using a multi-disciplinary approach
based on different space-borne observations., including ten years of GRACE measurements and four Landsat
ETM+ images (2003, 2006, 2009, and 2013) covering the surface area of Lake Nasser. The results are evaluated
and compared with Satellite Altimetry.
Keywords: Water storage; Water Level; Landsat; GRACE; Altimetry; Lake Nasser.
23
New gravity grid and geoid model of Tahiti from airborne and terrestrial gravity
surveys
C. Hwang1, J-.P. Barriot2, H.C. Shih3, M. Mouyen4, J.C. Han1, Pascal Corréia5, D. Lequeux5, and L. Sichoix2
1
Department of Civil Engineering, National Chiao Tung University, Hsinchu 300, Taiwan.
2
Geodesy Observatory of Tahiti, University of French Polynesia, 98702 Faa’a, Tahiti.
3
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan.
4
5
Institute of Earth Science, Academia Sinica, Taipei, Taiwan.
Service de l'Urbanisme de la Polynésie française, Papeete, Tahiti.
Abstract: This paper reports the preliminary result of an airborne gravity survey in Tahiti conducted in July-August
of 2013. The aim of the survey is to improve the gravity field and the geoid model of Tahiti. In the survey, a LCR
System II S130 air/sea gravimeter and a geodetic GPS receiver were mounted on a Britten-Norman BN-2 Islander
aircraft to collect airborne gravity readings along 25 lines at an mean altitude of 322 m. The survey covers two
major islands of Tahiti, Papeete and Moorea, in 60 flight hours, and the RMS crossover difference of the airborne
gravity anomalies is 2.94 mgal. A notable contribution is gravity anomalies over the inaccessible high mountain of
the two islands. New land gravity values, at the 0.03 mgal accuracy level, on the two islands were also collected
using a CG-5 gravimeter. Gravity anomalies in the waters off the islands are determined from retracked ERS-1/GM
and Geosat/Gm altimeter data and Cryosat-2 altimeter data. A new geoid model for Papeete and Moorea is
constructed. An initial assessment shows few cm of discrepancies between the modelled and true geoidal heights in
Papeete, despite some large discrepancies; the final geoid assessment will be given in the paper. There is about a
30-cm difference between the vertical datums of Papeete and Moorea. We will also present new, combined free-air
and Bouguer anomaly grids of Tahiti for geophysical studies.
Evaluation of GOCE/GRACE GGMs over Argentina with GPS/Leveling and
gravity anomaly data
C.N. Tocho1, G.S. Vergos2
1
Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina, [email protected].
2
[email protected].
Abstract: With the GOCE mission having reached its end, an unprecedented volume of gravity field related data
have become available. From the use of GOCE gradients alone or in combination with GRACE and/or terrestrial
data, a significant amount of Global Geopotential Models (GGMs) have become available employing various
amounts of GOCE information, i.e., releases 1, 2, 3 and 4 while the 5th generation models are expected using the
lower altitude GOCE observables. Moreover, given a methodological scheme for the GOCE data analysis various
GGMs were generated, namely the TIM, DIR and SPW ones along with combination models such as GOCO and
EIGEN-XXc. The focus of this work is put on the evaluation of all available GOCE/GRACE GGMs, both satellite
and combined ones, over Argentina. To this extent, GPS/Leveling collocated geoid heights are used along with
terrestrial free-air gravity anomalies. EGM2008 is used as the ground truth GGM against which all others are
compared and evaluated. In order to reduce the omission error due to the limited harmonic expansion of the
24
GOCE/GRACE GGMs, synthetic GGMs are evaluated by adding to the satellite models signal from EGM2008 and
topographic effects through an RTM model. The evaluation is performed with an incremental step of one in
harmonic degree, so that the most detailed possible evaluation of the GOCE/GRACE GGMs will be performed.
The RTM effects that represent the high ad ultra-high frequencies of the gravity field spectrum are evaluated over
the entire country through a 30 arcsec DTM, so that the effective maximum degree and order that it resolved is
216,000, i.e., the omission error is at the mm-level. Finally, from the spatial distribution of the differences between
the synthetic GGM and the GPS/Leveling and gravity data, some useful conclusions are drawn on the quality of the
latter over different parts of Argentina.
EIGEN-6C4 – The latest combined global gravity field model including GOCE
data up to degree and order 1949 of GFZ Potsdam and GRGS Toulouse
Ch. Förste1, F. Flechtner1, Ch. Dahle1, O. Abrikosov1, H. Neumayer1, Franz Barthelmes1,
R. König1, S.L. Bruinsma2, J.C. Marty2, J.-M. Lemoine2, R. Biancale2
1
GFZ Potsdam, Dept. Geodesy and Remote Sensing, Telegrafenberg, D-14473 Potsdam, Germany
2
CNES/GRGS, 18, avenue Edouard Belin, F-31055 Toulouse, France
(e-mail: [email protected] ; [email protected])
Abstract: GFZ Potsdam and GRGS Toulouse have a long-time close cooperation in the field of global gravity field
determination. Here we focus on (1) GOCE gravity field determination and (2) computation of high resolution
combined gravity field models. Such data products play a fundamental role in geodesy and Earth sciences, ranging
from practical purposes, like precise orbit determination, to scientific applications, like investigations of the density
structure of the Earth’s interior. Here we present our combined gravity field model EIGEN-6C4 which is the fourth
release of EIGEN-6C (EIGEN = European Improved Gravity model of the Earth by New techniques).
The first release of EIGEN-6C, published in 2011, was the first global combined gravity field model containing
GOCE data. It was computed from a combination of LAGEOS, GRACE and GOCE data, augmented with DTU10
surface gravity data, and it is complete to degree and order 1440 (corresponding to 14 km spatial resolution). The
combination of the different data types has been done on the basis of full normal equations up to maximum
degree/order 370. The spherical harmonic coefficients of the shorter wavelengths were obtained from a block
diagonal normal equation from the terrestrial data only. The subsequent releases EIGEN-6C2 (2012) and
EIGEN-6C3stat (2013) were complete to degree and order 1949 (corresponding to approx. 10 km spatial resolution)
and comprise extended measurement time spans for the LAGEOS/GRACE as well as for the GOCE data. Now we
present the new release EIGEN-6C4. This time variable combined gravity field model is again developed to degree
and order 1949 and comprises the new GRACE Release 03 from GRGS and gradiometer data almost of the entire
GOCE mission (Sept. 2009-Sept. 2013). Our combination of GRACE and GOCE data allows the construction of an
accurate satellite-only contribution to the final combined model up to degree and order 260, where the GOCE
gradiometer data contribute only for degrees upwards of 100. This is achieved through filtering of the GOCE
observation equations, which is necessary because of the degraded gradiometer performance outside the
measurement bandwidth. Consequently, surface data normal equations are combined with the satellite normal
equations at a higher degree than formerly applied before the GOCE launch (for instance at degree 70 in
EIGEN-5C). The comparison of test results (orbit computation, GPS leveling, geostrophic current speeds) of this
latest EIGEN model with GOCE-only models, EGM2008, GGM03 and GRACE-ITG2010S demonstrates the gain
in accuracy at high degrees, while its performance is identical to recent GRACE-only model for the low degrees.
25
Compared to the precursor releases of EIGEN-6 this new release shows a general improvement. EIGEN-6C4 is
available at the ICGEM data base at GFZ Potsdam via http://icgem.gfz-potsdam.de
The GOCE processing within this work has been done in the framework of the European GOCE Gravity
Consortium (EGG-C) under ESA contract within the ESA GOCE High Level Processing Facility (GOCE-HPF).
A detailed geoid model of Taiwan for height modernization, vertical datum
connection and Lidar mapping
Cheinway Hwang 1, Hung-Jui Hsu1, Ming Yang2 and Yi-Hsing Tseng2
1
Dept of Civil Engineering, National Chiao Tung University, No. 1001, Ta Hsueh Road, Hsinchu 300, Taiwan. [email protected]
2
Dept of Geomatics, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan
Abstract: This paper shows a band-limited least-squares collocation method to form new grids of gravity anomalies
from gravity data collected in airborne, shipborne and terrestrial surveys using mobile and static gravimeters. The
various gravity datasets contain different error sources and varying spatial resolutions. Some 6000 new land gravity
values, at the 0.03-mgal accuracy, make a notable contribution to the grids. We combine CRYOSAT-2 and retracked
ERS-1/GM and Geosat/GM altimeter-derived sea surface heights to determine improved coastal gravity around
Taiwan and the north South China Sea, which is then merged with the terrestrial gravity data. The new gravity field
is used to construct a detailed geoid model of Taiwan. Validations using GPS and leveling data show that the model
accuracies are between few cm to dm over different terrains. Height modernization of Taiwan is based on this new
geoid model and a real-time GPS network. The geoid model reveals that the vertical datum differences between the
main island and some offshore islands range from few cm to more than 80 cm at an island facing the Kuroshio
Current. A new DEM for the most part of Taiwan, referring to the vertical datum of Taiwan through a hybrid geoid
model, is constructed from Lidar-derived ellipsoid heights.
Band-limited topographic mass distribution generates full-spectrum gravity field
– gravity forward modelling in the spectral and spatial domains revisited
Christian Hirt, Michael Kuhn
Western Australian Centre for Geodesy, Curtin University, Perth, Australia
Abstract: Forward modelling of the gravity field from topography models plays an important role in physical
geodesy, e.g., to predict a detailed gravity field or to reduce observed gravity values. Gravity forward modelling
can be carried out either in the spectral domain (via harmonic series expansions) or spatial domain (via numerical
integration techniques). In previous numerical comparisons between both techniques, notable discrepancies up to
~10% (10-1 in terms of relative errors) were encountered. Most of the previous studies on gravity forward
modelling in the spectral domain truncate the gravitational potential spectra at a resolution commensurate with the
input topographic mass model. This implicitly assumes spectral consistency between topography and implied
topographic potential. Our contribution demonstrates that a band-limited topographic mass distribution generates
gravity signals with spectral energy at spatial scales far beyond the input topography’s resolution. The spectral
26
energy at scales shorter than the resolution of the input topography is associated with the contributions made by
higher-order integer powers of the topography to the topographic potential. The p-th integer power of a topography
expanded to spherical harmonic degree n is found to make contributions to the topographic potential up to
harmonic degree p times n. New numerical comparisons between Newton’s integral evaluated in the spatial and
spectral domain are presented showing this previously little addressed truncation effect to reach amplitudes of
several mGal for topography-implied gravity signals. Modelling the short-scale gravity signal in the spectral
domain improves the agreement between spatial and spectral domain techniques to the microGal-level, or below
10-5 in terms of relative errors. Providing an explanation for the discrepancies between forward modelling
techniques in previous studies, our findings have important implications for the use of gravity forward modelling.
The topographic potential in spherical harmonics must be calculated to a much higher harmonic degree than
resolved by the input topography if mutual consistency between topography and implied potential is sought. With
the improved understanding of the spectral modelling technique in this presentation, theories and computer
implementations for both techniques can now be significantly better validated.
GGMplus (Global Gravity Model plus) – an ultra-high resolution near-global
model of Earth’s gravity field
Christian Hirt1,2, Michael Kuhn1, Sten Claessens1, Moritz Rexer1,2, Roland Pail2, Thomas Fecher2
1
Western Australian Centre for Geodesy, Curtin University, Perth, Australia
2
Institute for Astronomical and Physical Geodesy, Technical University Munich,
Germany Email: [email protected]; [email protected]
Abstract: A number of engineering and geosciences disciplines require precise knowledge of the Earth’s gravity
field structure with high resolution. In the past, gravity field modelling efforts either placed focus on representation
of local detail over regionally limited areas or global coverage with limited resolution. Only recently global
modelling of Earth’s gravity field with local detail has become feasible with advances in methodology and use of
large-scale supercomputing facilities. A joint Curtin University-TU Munich research initiative has embarked on
these possibilities and created an ultra-high resolution (i.e., 250 m in the space domain) model of the Earth’s
gravity field with near-global coverage: GGMplus (Global Gravity Model plus). GGMplus is constructed as a
composite model of GOCE/GRACE and EGM2008 data and forward-modelled short-scale gravity effects from the
SRTM global topography. The SRTM short-scale gravity field modelling was computationally demanding and
required massive parallelization and use of supercomputing facilities. GGMplus comprises digital maps of gravity
disturbances/accelerations, quasi/geoid heights and deflections of the vertical. The maps provide estimates for
gravity field functionals at 3,062,677,383 points covering all continents, islands and coastal zones within the SRTM
data availability (60 degree North/ 56 degree South latitude). We expect the outcomes of our initiative to be
beneficial for applications such as in-situ reduction of gravimetric surveys, GNSS height transfer and
gravity-related reductions (e.g., in the context of height systems and surveying), which all require spectrally
complete information on the gravity field. Further, GGMplus provides reasonable constraints on the expected
extreme values (e.g., maximum deflection of the vertical) on Earth. GGMplus was created with the support of the
German Universities Excellence Initiative (via TUM’s Institute of Advanced Study) and the Western Australian
iVEC supercomputing facility. The model is publically available via http://ddfe.curtin.edu.au/gravitymodels/ and
http://geodesy.curtin.edu.au/GGMplus/ .
27
Factor analysis of the differences between the gravimetric geoid model and the
observed geoid undulations by using GPS/Leveling
D. R. Roman1, X. Li2, Y.M. Wang1, and D. A. Smith1
1
National Geodetic Survey, NOAA Silver Spring MD 20910
2
DST contract support to NGS, Lanham, MD 20706
Email: [email protected] Tel: +1(301)713-3202x210
Abstract: Previous studies had shown that there are relatively large differences between the gravimetric geoid
models (such as EGM2008, USGG2009 and USGG2012) and the GPS/Leveling observed geoid heights.
Considering the current accuracy of GPS and the middle-to-long wavelength geoid model components, the main
part of the differences between the model implied geoid undulation and the ground observed geoid heights is
believe to be the orthometric datum error in the current vertical datum, i.e., NAVD88(North American Vertical
Datum of 1988). Because the original leveling survey and its associated computations and adjustments were
finished long time ago, it is very challenging to find out the specific reasons of the datum error and completely
remove it. However, for engineering purposes, it is often required to transform the gravimetric geoid to fit into the
official vertical datum that may be subjected to errors. During the transforming, some directly simple parameter
fitting technique such as polynomial fitting will cause undesirable artifacts that produce negative correlations with
increasing of the distance; while the full power of the harmonic analysis is limited because of the no global or
evenly distributed GPS/Leveling benchmarks. Novel analysis technique has to be applied to overcome these
difficulties. If we could suppose that the geoid differences are caused by a few factors that we did not observed
directly, the idea of factor analysis could be applied to estimate these reasons out. Thus, the principle component
based factor analysis is employed to estimate the underlying reasons of the NAVD88 errors. The results based on
the analysis of the 24,616 benchmarks in CONUS (Contiguous United States) and Mexico showed that about 99%
of the geoid differences can be explained by only using 3 factors. Moreover, the factor scores show that the first
factor is primarily terrain related, while the other two main factors are corresponding to the north-south trend and
the east-west trend, respectively.
Bayesian estimation of geological provinces from GOCE data
Daniele Sampietro1, Mirko Reguzzoni2
1
GReD s.r.l., Via Valleggio 11, 22100 Como, Italy
2
DICA, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
Abstract: For the first time with the GOCE mission a medium-high resolution image of the Earth steady state
gravitational field has been globally observed with high accuracy. Besides the geodetic and oceanographic
applications, also Solid Earth geophysics can take advantage of the newly available observations. Several studies
have already shown the possibility of using GOCE data to infer the Moho depth and also other information on the
Earth crust.
In this work a global map of physiographic provinces, i.e. a map of geographic regions characterized by being
homogeneous from the geologic or geomorphic point of view, is developed starting from GOCE observations.
More specifically this result is obtained by introducing as prior information a given map of the main geological
provinces and trying to adjust their boundaries according to the GOCE data in a Bayesian scheme.
28
In this way the Earth crust has been classified in eight main categories: shield, platform, orogen, basin, large
igneous province, extended crust, oceanic crust and mid-oceanic ridges. The method has been tested in a close-loop
scenario, showing its capability to correct wrong a priori province boundaries, and applied to real data to revise the
currently available province partitioning.
Improving estimability in strapdown airborne vector gravimetry
David Becker, Matthias Becker, Stefan Leinen, Yingwei Zhao
Physical and Satellite Geodesy, Institute of Geodesy, Technische Universitaet Darmstadt, Darmstadt, Germany
Abstract: Estimability, as used in this paper, is a measure of observability, based on the information matrix of a
discrete linear system. The estimability of IMU/GNSS-integrated systems has been discussed in several
publications. This paper adopts this concept for the field of strapdown airborne vector gravimetry by analysing the
estimability of three-dimensional gravity anomalies δg. Using DGNSS-position updates only, previous works have
already shown that the estimation of the horizontal components of δg (i.e. the deflection of the vertical, DOV)
suffers from its correlation with attitude errors (roll and pitch). In order to improve the estimability of δg, we
analyse two fundamental strategies: 1.) introducing additional observations: GNSS-derived velocities and attitude
measurements, and long-wavelength observations of δg (e.g. taken from EGM). In particular, attitude
measurements can be shown to improve the DOV's estimability. 2.) Rotating the IMU and/or performing flight
maneuvers: While for scalar gravimetry (vertical component only) a smooth, linear flight trajectory is in general
beneficial, it can be shown that by rotating the strapdown IMU's sensor-triad around its axes with e.g. 10s per cylce,
the DOV's estimability can be improved. Rotations around the vertical axes implicitly enable the separation of the
DOV and attitude errors. Also, short-term accelerometer bias changes may become estimable using this technique,
which can be in particular interesting when applied to systems with tactical-grade IMUs. Several test scenarios are
simulated using combinations of the strategies mentioned above. Based on a Kalman-Filter-evaluation, the
corresponding impacts on estimability and on actual errors will be presented and analysed.
Gravity surveys and quasi-geoid model for South America
Denizar Blitzkow1, Ana Cristina Oliveira Cancoro de Matos1, Daniel Silva Costa1,
Gabriel do NascimentoGuimarães2, María Cristina Pacino3, Eduardo Andrés Lauría4,
Carlos Alberto Correia e Castro Junior5, Afrânio de Mesquita Filho6
1
2
3
Escola Politécnica, Universidade de Sao Paulo (USP), Brazil, [email protected]
Instituto de Geografia, Universidade Federal de Uberlândia (UFU), Brazil, [email protected]
Facultad de Ciencias Exactas, Ingenierí
a y Agrimensura (FCEIA), Universidad Nacio-nal de Rosario, Argentina,
[email protected]
4
5
Instituto Geográfico Nacional,Argentina, [email protected]
Instituto Brasileiro de Geografia e Estatística (IBGE), Unidade Estadual de Goiás, Bra-zil,
6
[email protected]
Instituto Oceonográfico da Universidade de São Paulo, [email protected]
Abstract: A general overview on the constant progress in the gravimetric densification efforts and the calculation of
the quasi-geoid model for South America are presented. The recent efforts for gravimetry surveying in South
America involved the north (Acre state) and southwest (São Paulo and Minas Gerais states) of Brazil, Argentina
(northwest region), Paraguay (northwest region of the Paraguayan Chaco) and Ecuador (Napo e Aguarico rivers,
29
Amazon region). GEOID2014 computation was carried out in the area limited by 15ºN and 57ºS in latitude and
30ºW and 95ºW in longitude. The model was based on EIGEN-6C3stat up to degree and order 200 as a reference
field. The oceanic region was completed with the mean free-air gravity anomalies derived from a satellite altimetry
model from the Danish National Space Center, called DTU10. The short wavelength component was estimated via
FFT. The GGMs EIGEN-6C3stat, GOCO03S, GO_CONS_GCF_2_DIR_R4, GO_CONS_GCF_2_TIM_R4 out of
the new quasi-geoid model have been evaluated against 1861 GPS observations on Bench Marks(GPS/BM),
where 1113 points are located in Brazil. Preliminary RMS difference between GPS/BM and Geoid2014 geoidal
heights, in the whole South America and just in Brazil, are 0.55 m and 0.44 m, respectively, the mean values are
0.17 m and 0.02 m. New projects is starting with the support of GEORADAR Levantamentos Geofí
sicos S.A. and
IGC (Instituto Geográfico e Cartográfico) under the coordination of LTG and CENEGEO (Centre for Geodesy
Studies). The first project aims to establish an Earth tide model in São Paulo state using two Microg LaCoste
gPhone gravitymeters. The second project aims to establish fundamental gravity points with A-10 absolute
gravitymeter in South America. The gPhones were installed in the campus of the University of São Paulo and at the
Abrahão de Moraes observatory, in São Paulo and Valinhos cities, respectively. The sites belong to the Institute of
Astronomy, Geophysics and Atmospheric Sciences of the University of São Paulo (IAG-USP). They also worked to
Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), in Presidente Prudente and in the ocean research
base Dr. João de Paiva Carvalho, Oceonographic Institute of the University of São Paulo (USP), located in
Cananeia city. The two equipments re-mained for more than six months in each location. The softwares Tsoft and
ETERNA have been used for the pre-processing and for the tide analysis, respectively. This project will also aim to
establish 5 stations well distributed in Brazil, one of long term in Manaus, Amazon, and 4 others in a sequence of
one year operation in different places. The A-10 Absolute Gravitymeter is working around São Paulo State and
Argentina establishing fundamental gravity points with high precision. In the future, the absolute gravity survey
will be done around Brazil too and it will be used for controlling gPhone drift when necessary.
Accurate Approximation of Vertical Gravity Gradient within the Earth’s
External Gravity Field
Dongming Zhao, Qingbin Wang, Huan Bao, Shanshan Li
Zhengzhou Surveying and Mapping Institute, Information Engineering University
Zhengzhou, Henan Province, 450052
Abstract: Vertical gravity gradient plays an important role in the research of the Earth’s gravity field. However, the
measurement of the vertical gravity gradient is a hard work. With the fast development of the Earth’s gravity field
model, it is possible to accurately approximate the vertical gravity gradient with the aid of the gravity field model
as well as increasing gravity anomalies and rich terrain data. In the paper, a theoretical analysis was made on the
computation of the vertical gravity gradient firstly, and then two methods, the remove-and-restore method, and
point mass method, were used to accurately approximate the vertical gravity gradient. Tests of the two methods
were made using some actual measurements of vertical gravity gradient over china, and analyses were also made.
At the end of the paper, some issues on the vertical gravity gradient to be further investigated were proposed.
Key words: vertical gravity gradient; the Earth’s gravity field model; remove-and-restore method; point mass
method
30
Improvement of GOCE Level 1b Gradiometer Data Processing Over Magnetic
Poles
E. S. Ince and S. Pagiatakis
Dept. of Earth and Space Science and Engineering, Lassonde School of Engineering, York University, Toronto, Ontario, M3J 1P3,
Phone: 416-736-5245 Fax: 416-736-5817, Email: [email protected], [email protected]
Abstract: The latest gravity field mission GOCE, has mapped the Earth’s gravity field with an unrivalled precision.
Being the first satellite of its kind and having a unique instrument onboard make GOCE special. Nevertheless, this
also makes GOCE data and its’ processing challenging. In order to solely observe and map the Earth’s static
gravitational field, the influence of all other temporal gravitational and non-gravitational effects should be
eliminated from GOCE gradiometer observations. In this study, the leakage of the non-gravitational forces into the
gradiometer data is sought and the reasons behind this kind of deficiency are investigated. It is found that the
attitude of GOCE has been affected by unexpected external sources, such as solar wind and magnetic storms
around the magnetic poles. Under optimum conditions, such non-gravitational effects should be measured by
accelerometers and compensated. However, it is seen that the effects of these phenomena leak into the
differential-mode accelerations, which should include only gravitational forces and angular accelerations of the
satellite. Moreover, these effects are observed in the diagonal gravity gradient tensor components that are used in
the development of static gravity field models. It is also seen that the GPS antenna onboard has experienced
tracking losses in these regions. This makes the position of the satellite unavailable and the orbit solution less
accurate in these regions. All these effects may degrade the final products such as gravity field models and geoid.
Accordingly, the separation between the gravitational and non-gravitational accelerations should be performed very
cautiously. Our study seeks whether it is possible to improve this separation by having the geomagnetic field
components computed along the satellite track and eliminate the possible correlation between the gravity and
geomagnetic fields in GOCE data.
The ICGEM: an IAG Gravity Field Service
F. Barthelmes, W. Köhler
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany,
[email protected]
Abstract: Since 2003 the International Centre for Global Earth Models (ICGEM) is established as an IAG service
under the roof of the International Gravity Field Service (IGFS). The major task of ICGEM is to make all global
gravity field models of the Earth, which are provided as sets of spherical harmonic coefficients, available to the
public. This covers the most recent models back to historical data. The spherical harmonic coefficients are available
in a standardised self-explanatory format. The models can not only be downloaded from the ICGEM website
(http://icgem.gfz-potsdam.de/ICGEM) but also be used within an interactive visualisation tool and in a dedicated
gravity function calculation service. The visualisation service shows the models (or the difference of two models)
in terms of height anomalies or gravity anomalies as illuminated projection on a freely rotatable sphere.
Additionally, an animation over time of the monthly solutions from GRACE is included. Finally, the calculation
service provides the possibility to compute different functionals of the gravity field, such as gravity anomalies,
geoid undulations or equivalent water heights on grids of the users’ choice. In particular, thanks to the availability
31
of the 10-years monthly model series from GRACE, the static models from the recent GOCE mission, and their
combined models of high spatial resolution, the importance of gravity field functionals for nearly all geosciences is
rising permanently. In addition to its use for educational purposes, ICGEM helps researchers from different
geoscientific fields to overcome the first obstacles in using these models and to get acquainted with the
mathematical representation of gravity field in terms of spherical harmonic series. In this way ICGEM enables and
stimulates the research based on these products.
Land-ocean leakage effects on Glacier mass loss estimate from GRACE in
Greenland
Fang Zou1, 2, Shuanggen Jin1
1
2
Email: [email protected], Tel: 86-21-34775293; Fax: 86-21-64384618
Abstract: The Gravity Recovery and Climate Experiment (GRACE) satellite launched in 2002 can offer
high-precision time-varying gravity field and the changes of Earth’s surface mass, which have been widely used in
geodesy, hydrology, oceanography and glaciology. However, one of larger errors in GRACE measurements,
land-ocean leakage error, restricts high accuracy retrieval of ocean mass or terrestrial water storage along the coasts.
The land signals will contaminate the ocean signals with significant signal attenuation, particularly the
glacier-ocean leakage errors in Greenland. In this paper, land-ocean leakage errors on glacier mass loss estimate in
Greenland from GRACE are investigated using the forward gravity modeling. The strong secular glacier mass loss
is found over Greenland using time-varying GRACE gravity field with the period from January 2003 to February
2013 (about 10 years), and the forward gravity modeling will greatly reduce the land-ocean leakage errors.
Keywords: Leakage effects; Glacier melting; Greenland; GRACE
Evaluation of GOCE/GRACE GGMs over Attika and Thessaloniki, Greece, and
Wo determination for height system unification
G.S. Vergos1, V.D. Andritsanos2, V.N. Grigoriadis1, V. Pagounis2, I.N. Tziavos1
1
[email protected]
2
Department of Civil Engineering and Surveying & Geoinformatics Engineering, Technological Educational Institute of Athens,
Greece
Abstract: Within the frame of the “Elevation” project, supported by the action “Archimedes III – Funding of
research groups in T.E.I.”, co-financed by the E.U. and Greek national funds, an extensive evaluation of collocated
GPS and leveling observations over trigonometric benchmarks (BMs) in Greece has been carried out, aiming at the
unification of the Greek Local Vertical Datum (LVD). The evaluation refers to newly and previously acquired GPS
ellipsoidal heights over Leveling BMs that belong to the Greek LVD, in order for the determined geometric geoid
heights to be used for the validation of GOCE and GRACE contribution, through the available Global Geopotential
Models (GGMs), over Greece. To this extent all available satellite-only and combined GOCE/GRACE GGMs were
32
evaluated to conclude on the possible improvement brought by GOCE, given the various methodologies used for
the GGM development (DIR, TIM, SPW, GOCO, EIGEN) and the various releases of GOCE data (Release 1, 2, 3,
4 and 5). Absolute as well as relative differences, as functions of the baseline lengths between the BMs, were
studied, in order to conclude on the appropriateness of GOCE/GRACE GGMs within a GPS/Leveling orthometric
height determination scheme. At a second stage, we focused on the determination of the geopotential value
W0
LVD
for the Greek LVD. Given that the BMs used belong to two distinct areas under study, i.e., one over Attika and
another in Thessaloniki, the
W0
LVD
determination was initially carried out for each region seperately, in order to
conclude on the possible biases of the Hellenic LVD itself. Then, a national and consistent
W0
so that the Greek LVD could be homogenized into a Global VD. The estimation of
W0
was determined
LVD
LVD
was carried out
employing two different methodologies. The first one is based on the differences between geoid heights from
GPS/Levelling measurements and those derived from EGM2008 and GO-DIR-R4. The estimation of the mean
offset can give us a direct link between the Greek LVD and the IAG conventional value. The second method
consists of a least squares adjustment of Helmert orthometric heights using surface gravity disturbances and
geopotential values computed from EGM2008 and GO-DIR-R4 over the available entire GPS/Levelling network.
Quasi-geoid model in the State of São Paulo
Gabriel do Nascimento Guimarães1,Denizar Blitzkow2, Ana Cristina Oliveira Cancoro de Matos2
1
Instituto de Geografia, Universidade Federal de Uberlândia (UFU), Brazil, [email protected]
2
Escola Politécnica, Universidade de São Paulo (USP), Brazil, [email protected]
Abstract: Since 2008, some efforts have been undertaken in terms of gravity measurements in the State of São
Paulo with the aim to improve de geoid model. Gravity data coverage is quite complete in the area for a 5’
resolution. In addition, field works are being undertaken to fill the gaps around the state. This is a result of FAPESP
(Foundation of the State of São Paulo) Thematic Project that aims to carry out the establishment of a geoid model, a
height system and the study of the possible vertical crust movement. The project involves several laboratories of
Brazilian universities. These efforts resulted in a geoid model called GEOIDSP, limited by 19ºS and 26ºS in latitude
and 44ºW and 54ºW in longitude, which has been derived using three methodologies: the modified Stokes integral
through Fast Fourier Transform (FFT) and Numerical Integration (NI), and the Least Square Collocation (LSC).
Another objective of this study is to verify the potentiality of GOCE-based models. The spectral decomposition was
employed in the geoid models computation and the long wavelength component was represented by EGM2008 up
to degree and order 150 and GOCE-based models up to degree and order 150 and 210. The models were compared
in terms of geoid height residual and absolute and relative comparisons from GPS/leveling and the results show
consistency between them. Also, a comparison in the mountain regions was carried out to verify the methodologies
behavior in this area; the results showed that LSC is less consistent than FFT. Regarding GOCE-based models, 7
were tested, besides EGM2008. The evaluation was performed in terms of geoid height comparison obtained by
GGMs over GPS/leveling and in terms of gravity disturbance. At the same time, an absolute gravity network was
started to be established in the state. In the total 18 stations are being measured (15 news and 3 re-occupations).
They will be deployed at strategic places and in locations that have the Brazilian Network for Continuous
Monitoring (RBMC) stations. Thus, the user will have available at least one station within a radius of 100 km.
33
Measures are being conducted using an absolute gravimeter model A-10 microg LaCoste.
Study on Density structure chatacters of Xiaojiang fault system
Guangliang Yang 1,2,3, Chongyang Shen 2,3, Hongbo Tan 2,3, Guiju Wu 2,3 and Jiapei Wang 2,3
1
Geodynamics Laboratory, College of Earth Sciences, Graduate University of CAS, Beijing 100039;
2
Earthquake Administration of Hubei Province, Wuhan 430071;
3
Crustal Movement Laboratory, Wuhan 430071
Abstract: Xiaojiang fault system is important part of tectonic movement in the eastern margin of the Qinghai-Tibet
Plateau, formed a complex deep tectonic structure with strong tectonic movement in the east boundary of
Sichuan-Yunnan block. We analysised separately density distribution of Xiaojiang fault system’northern、middle
and southern section by the way of bouguer residual density correlation imaging and Normalized full gradient, with
five cross-fault short gravity profile. The study indicated that Xiaojiang fault system is with the depth structure
chatacters of lateral block and vertical stratification. The model of the fault system cross-fault gravity profile and
three-dimensional space tectonic, based on rich geological and geophysical data in the area, provided the physical
basis for the research of earthquake evolution in the area and material flow, dynamic environment in the eastern
margin of the Tibetan Plateau.
Key words: Xiaojiang fault system; East boundary of Sichuan-Yunnan block; Gravity profile; Correlation imaging;
Normalized full gradient
Uncertainty of ice sheet contributions to global sea level change from GRACE in
2003-2012
Guiping Feng1, 2, Shuanggen Jin1
1
2
Tel: 86-21-34775293; Fax: 86-21-64384618
Abstract: Mass losses of the polar and mountain glaciers are one of the main contributors to the current eustatic sea
level rise for recent global warming. However, due to complex ice-sheet condition and sparse in-situ measurements,
accurate quantification of global ice-sheet mass loss contribution to sea level rise is still difficult. The Gravity
Recovery and Climate Experiment (GRACE) mission launched in 2002 provides a means of unprecedented
accuracy and tempo-spatial resolutions to quantify global ice-sheet mass variations. In this paper, we use the
GRACE RL05 data from Jan. 2003 to Dec. 2012 to quantify the ice melting contributions to sea level rise and
evaluate their uncertaintyies. Our results show that the total ice melting contributions to sea level rise is 2.09±0.54
mm/yr from 2003 to 2012, including 0.72±0.12 mm/yr from Greenland, 0.59±0.10 mm/yr from Antarctic and
0.63±0.09 mm/yr from mountain glaciers. Furthermore, the effects of GIA models, land-ocean leakage error,
smoothing methods and geocenter are investigated and discussed. Results show the land-ocean leakage error is one
of main error sources in estimating ice sheet contributions to global sea level change.
Keywords: Ice melting, GRACE, Sea level change, Uncertainy
34
Pendulum Orbit Configuration Analysis and Its Application in Earth Gravity
Field Inversion
H. Zhou 1, Z. C. Luo 1,2,3, B. Zhong 1,2, and Q. Li1
1
School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China
2
Key Laboratory of Geospace Environment and Geodesy, Ministry of Education,
129 Luoyu Road, Wuhan 430079, China,
3
State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing,
129 Luoyu Road, Wuhan 430079, China
Abstract: GRACE has improved the long and medium wavelength earth static gravity signal significantly during its
last decade period of operation, and has derived earth system mass variations for the first time from space. However,
the north-south satellite-to-satellite tracking mode disturbs the temporal signal with obvious strip errors in the
monthly gravity field solutions, which limited GRACE’s ability of depicting the short-time and
high-spatial-resolution temporal variations. Compared with the GRACE single-orbit plane, pendulum orbit is the
orbit configuration to get observations not only in the north-south direction, but also in other directions, which can
obtain isotropic earth gravity signals simultaneously. Hence, a simulation analysis in terms of pendulum orbit
configuration is carried out in this study. Firstly, a closed-loop system was introduced to check the accuracy and
stability of our earth gravity field inversion software, the numerical results indicates that the dynamic integral
approach is reliable for this study. Then, in order to particularly comprehend the contribution of pendulum orbit
configuration in earth gravity field inversion, several numerical experiments are conducted as follows. (1)Since
satellites are waggled in pendulum orbit configuration, the relationship between the different maximum tilt angles
and repeat periods, track of sub-satellite points was built, and the relative earth gravity field inversion accuracy
including spatial and temporal resolution was compared. (2)In terms of two satellites formation, only the
north-south and west-east configurations were realized with GRACE and SWARM (without KBRR), respectively.
In this study, these two released missions are contrast with pendulum orbit configuration, where the simulative
payloads have the same observation accuracy with GRACE. (3)The concept of pendulum configuration was
introduced in E.MOTION mission proposal, which dedicated in obtaining the temporal gravity with spatial
resolution of 200 km. In order to analysis the potential of pendulum in obtain temporal signal, we also conduct the
temporal gravity model inversion at the E.MOTION accuracy grade in this study.
Key words: Pendulum orbit configuration; earth’s gravity field; dynamic approach; E.MOTION
Review and future prospects of inertial gravimetry and gradiometry systems
Haibing Li1,2, Michael G. Sideris2, Dongming Li1, Junhai Han1
1
Beijing Institute of Aerospace Control Devices, Beijing, China, 100039;
2
Department of Geomatics Engineering, University of Calgary, Calgary, Alberta, Canada, T2N 1N4
Abstract: Gravity data is very important spatial information for geodesy, geophysics, oceanography and other
applications such as aided navigation. With the development of GNSS (Global Navigation Satellite Systems) and
high precision INS (Inertial Navigation Systems), inertial gravimetry and gradiometry on moving platforms, such
as land vehicles, ships, aircrafts and satellites, became possible by GNSS/INS integration and played an important
role in quick, efficient and large-scale gravity measurements in the last decades. The accuracy requirements of
35
gravity data for different fields like geophysics and geodesy are reviewed and analyzed firstly. Secondly, the key
technologies involved in the measurement system hardware, for example, sensors and different kinds of
mechanization (physical platform stabilization, mathematic platform stabilization, i.e., strapdown mode, etc.), and
data processing algorithms like Kalman filtering are presented. Then, the main measurement systems in operation
since 1995 or under development, their performances and the types of moving vehicles are summarized and
compared. Finally, several kinds of modern moving-platform gravimeter and gradiometer systems are discussed in
terms of the recent developments in the technologies of inertial sensors (especially acceleration sensors and
orientation sensors used), system integration and stabilized platforms.
Keywords: GNSS, INS, inertial gravimetry and gradiometry, stabilized platform, gyroscopes, accelerometers,
Kalman filtering
The decomposition and interpretation of continental water storage changes
derived from GRACE
Hanjiang Wen1, Zhenwei Huang1, Youlei Wang1, Huanling Liu2
1
Chinese Academy of Surveying and Mapping, Key Laboratory of Geo-information of National Administration of surveying, Mapping
and Geoinformation, 28 Lianhuachixi Road, Beijing, China 100830, [email protected]
2
Wuhan University, 129 Luoyu Road, Wuhan, China
Abstract: It is known that continental water storage variation can be detected by using Gravity Recovery and
Climate Experiment (GRACE) satellite gravity mission since 2002. The GRACE-derived spherical harmonic
coefficients can be used to study the mass redistribution within the Earth system with a 300km spatial resolution
and monthly temporal resolution. Since GRACE detected the total gravity changes, it is desirable to decompose the
observed total gravity change into different reasonable components. In this study we first use the independent
component analysis (ICA) method to decompose the continental water storage changes derived from 120 months
(2003.01–2012.12) GRACE RL05 gravity field, and then compare the results with those derived from NOAH and
WGHM hydrological models. The comparison results shows that the decomposed components from the water
storage changes and hydrological model agrees well, which indicates that ICA method can be used to separate the
independent signal components from the water storage observations with a few assumptions. The comparisons with
other methods, such as principal component analysis (PCA), are also conducted and discussed.
Real-Time Data Simulation of Electrostatic Accelerometer for geodetic Satellite
Hongyin Li1,2, Kun Wang1,2, Shaobo Qu2, Zebing Zhou2
1
2
School of automation, Huazhong University of Science and Technology
School of Physics, Institute of geophysics, Huazhong University of Science and Technology, Wuhan 430074, China
Abstract: The geodetic satellite is the only way to monitor the global gravity field. As the satellite is perturbed by
non-conservative forces, we need to measure the non-conservative accelerations acting on the satellite precisely for
gravity field inversion. Currently, these accelerations are accurately measured by using electrostatic accelerometers,
which have been applied in CHAMP, GRACE and GOCE missions.
In this work we build a numerical model of the electrostatic accelerometer in Simulink to simulate its dynamic
feedback control loop operation and measurement specification. In the numerical model we account for all major
36
sources of error including test mass position detection noise and feedback voltage noise. Drifting of bias according
to housing temperature variance on board is also included. In the simulation, we use the NRLMSISE-00 air density
model and the Box-Wing radiation pressure equation together with GRACE geometry as reference to generate the
aerodynamic drag and the solar radiation pressure acting on the satellite. The numerical model is implemented on a
real-time Simulink/xPC Target platform as shown in Fig1. With this simulator we can verify the control algorithm
of the accelerometer and simulate the data for future geodetic missions (see Fig.2). We also apply the scenario of
XX5 satellite and configurations of its accelerometer inside on the numerical simulator to validate the processing of
acceleration data.
Fig1. Real-time video output interface of accelerometer simulation
-7
x 10
Acc Readout Acceleration
3
X
Y
Z
2
m/s2
1
0
-1
-2
-3
0
0.5
1
1.5
Time(Sec)
2
2.5
4
x 10
Fig2. Output of 3 translation axis acceleration Simulation
Egyptian Geoid using Best Estimated Response of the Earth's Crust due to
Topographic Loads
Hussein A. Abd-Elmotaal
Civil Engineering Department, Faculty of Engineering, Minia University, Minia 61111, Egypt, [email protected]
Abstract: In the framework of the Egyptian geoid project, it is needed to compute the Egyptian gravimetric geoid
using the best estimated response of the earth's crust due to topographic loads. It has been proved that both the
37
inverse isostasy approach and direct isostasy approach (with Kelvin function Kei x) give practically the same
response of the earth's crust due to topographic loads (Abd-Elmotaal, 2013). This response of the earth's crust
matches that determined by seismic observation, known as seismic Moho depths (Abd-Elmotaal, 2000). Hence, this
best estimated response of the earth's crust due to topographic loads has been implemented in this paper for the
geoid determination process. The window remove-restore technique (Abd-Elmotaal and Kühtreiber, 2003) has been
used to avoid the double consideration of some of the topographic-isostatic masses in the neighbourhood of the
computational point. The gravimetric geoid is computed for Egypt using Stokes’ integral in the frequency domain
by 1-D FFT technique. The computed geoid is scaled/fitted to the GPS/levelling derived geoid. Internal and
external geoid accuracies are given and discussed.
Combination between Altimetry and Shipborne Gravity Data for Africa
Hussein A. Abd-Elmotaal, Atef Makhloof
Civil Engineering Department, Faculty of Engineering, Minia University, Minia 61111, Egypt
Abstract: In the framework of the African Geoid Project, it is needed to get the most complete and accurate gravity
data in sea region. Two gravity data sets in sea region are available. The first is the shipborne gravity data set, with
good accuracy and a lot of gaps. The second is the altimetry derived gravity anomalies, with uniform coverage and
less accuracy. This paper studies the best combination of these two gravity data sets. First, a gross-error scheme
within each data set separately has been carried out. Points having a difference greater than 4.5 mgal between the
measured and estimated gravity anomalies are considered a gross-error and thus have been removed. The shipborne
gravity data set, being the most accurate, has been considered the base and has been taken all (after the gross-error
removal). The differences between the altermetry derived gravity anomalies and the shipborne gravity anomalies at
the altimetry data points have been computed. Altimetry derived gravity anomalies are removed if they have
differences to the shipborne gravity anomalies greater than 20 mgal. The results are shown and widely discussed.
Establishment of the Gravity Database for the African Geoid
Hussein A. Abd-Elmotaal1, Kurt Seitz2, Norbert Kühtreiber3, Bernhard Heck2
1
Civil Engineering Department, Faculty of Engineering, Minia University, Minia 61111, Egypt
2
Geodetic Institute, Karlsruhe Institute of Technology, Englerstrasse 7, D-76128 Karlsruhe, Germany
3
Institute of Navigation, Graz University of Technology, Steyrergasse 30, A-8010 Graz, Austria
Abstract: In the framework of the African Geoid Project, it is needed to have a uniform gridded gravity data set to
compute the geoid using Stokes’ integral in the frequency domain by 1-D FFT technique. The available gravity data
set consists of land point gravity data as well as shipborne and altimetry derived gravity anomalies data. The
available gravity data set has a lot of significant gaps allover the continent. The establishment of the gravity
database for the African geoid has been carried out using an iterative process employing a tailored reference model
and weighted least-squares prediction technique. The point gravity data on land has got the highest precision, while
the shipborne and altimetry gravity data got a moderate precision. In each iteration step, the data gaps are filled
with the tailored reference model computed at the previous iteration step, getting the lowest precision within the
prediction technique. The weighted least-squares prediction technique is thus carried out to estimate gridded gravity
anomalies, which are used to estimate a new tailored reference model employing a least-squares harmonic analysis
technique. The iterative process works in such a way that it truncates the solution when two successive tailored
38
models are practically the same. The gravity database on a uniform grid of 6' × 6' has been established by the
developed process. The estimation of the interpolated gravity anomalies are given and widely discussed.
Validating methods to infer mass changes from satellite gravity measurements
using Synthetic Earth Gravity Modelling
I.M. Anjasmara1,2, M. Kuhn2, J. Awange2
1
Department of Geomatics Engineering, Sepuluh Nopember Institute of Technology, Kampus ITS Sukolilo, Surabaya 60111, Indonesia,
Fax : +62 31 5929487, E-mail: [email protected]
2
Western Australian Centre for Geodesy & The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987,
Perth, WA 6845, Australia
Abstract: Knowledge of the Earth's gravity field has been significantly improved by the introduction of the
dedicated satellite missions CHAMP (Challenging Mini-satellite Payload), GRACE (Gravity Recovery and Climate
Experiment) and GOCE (Gravity Field and Ocean Circulation Explorer). These missions indirectly derive mass
changes from detected gravity changes with unprecedented high spatial and temporal resolution and accuracy. This
has gained much interest amongst all geosciences as tool for improved understanding of Earth's processes.
To infer mass changes from gravity changes, various methods have been proposed. Due to the presence of
high-frequency errors and noise, these techniques frequently apply filters that imply spatial smoothing, which can
introduce considerable errors into the inferred masses due to leakage.
This study validates mass estimation techniques based on changes of the Earth's gravitational potential expressed in
spherical harmonics. A closed-loop validation procedure based on synthetic Earth gravity modelling is applied on
simulated mass distributions. Specific focus is on the leakage properties introduced by isotropic and anisotropic
smoothing techniques on the inferred mass.
The results of this study show that the use of filter techniques can introduce significant leakage effects leading to a
loss of signal of almost 70% under extreme circumstances. Furthermore, the smoothing filters introduce distortions
so that often the inferred mass distribution has little in common with the spatial extent of the simulated mass.
Previously not very well known, the performance of the mass recovery depends on the geographic location with
better recovery for masses located at higher geographic latitude.
Keywords: Space gravity, spatial and spectral leakage, validation, syntheticEarth gravity modelling, isotropic and
anisotropic filters, GRACE
The development of a new gravimetric geoid model for Greece: GGeoid2014
I.N. Tziavos, G.S. Vergos and V.N. Grigoriadis
[email protected].
Abstract: Regional/local geoid modeling and gravity field approximation employing heterogeneous data sources
has been the main part of geodetic research during the last decades. The geoid serves as the natural reference
surface to which heights for engineering works, geophysical and oceanographic applications refer to. The
availability of a national high-resolution and high-accuracy geoid model is of utmost importance for all surveying
39
related works taking part in a country, ranging from infrastructure development to land valuation. In Greece, even
though various geoid models have been developed during the last fifteen years, suffers from the fact that the official
geoid model has not been updated since the development of the Hellenic Geodetic Reference System in 1987.
Therefore, the determination of a new model based on the latest available datasets, both terrestrial and satellite, is
apparent. In this work we present the results from the determination of a new geoid model for Greece which is
based on a newly compiled gravity database employing all available land gravity, marine gravity, airborne gravity
and satellite altimetry data. The methodological steps for the generation of the final gravity data base are presented,
along with the evaluation of the available gravity data both w.r.t. EGM2008 and the latest GOCE/GRACE-based
GGMs. Geoid determination has been carried out using the well-known remove-compute-restore method, during
which the topographic effects are taken into account through an RTM model. Various intermediate solutions are
presented following both space-based and spectral methods, the former referring to LSC-based solutions and the
latter to FFT-based ones. The final models are validated against a network of 1542 GPS/Leveling BMs which cover
the entire part of the country, while a parametric LSC-based solution is developed in support of Leveling with GPS
applications.
Gravity field processing and error assessment of future LL-SST type satellite
missions using enhanced numerical precision
Ilias Daras, Roland Pail, Michael Murböck
Institute für Astronomische und Physikalische Geodäsie, Technische Universität München, Germany
Abstract: Next generation gravity field missions of low-low satellite-to-satellite tracking (LL-SST) type are
expected to fly at optimized formations and make use of the most accurate sensors, thus raising substantially the
expected temporal and spatial resolution, as well as the gravity field retrieval accuracy itself. A breakthrough is
planned with the improved LL-SST measurement instrument with an inter-satellite ranging measurement accuracy
of several nm, which is going to supplement the traditional K-band ranging system in the upcoming GRACE
Follow-on mission. Consequently, the processing method for gravity field recovery hastomeet the performance
requirements of those new generation sensors to deliver the most precise gravity field possible.
In this study we present an analysis of the potential performance of the new sensors and their impact on gravity
field solutions. We investigate the ability of current gravity field processing methods to fully exploit the new sensor
accuracies, by using full numerical closed-loop simulations in a realistic environment based on the Integral
Equation approach. We demonstrate that processing with standard precision may be a limiting factor for taking full
advantage of new generation sensors that future satellite missions will carry. Therefore we created an alternative
version of our simulator which uses hybrid mode double and quadruple precision at different processing steps,
primarily aiming to minimize round-off system errors. Results using the enhanced precision show a big reduction
of system errors that were present at the standard precision processing for an error-free scenario. As a next step,
an error budget analysis is performed using the enhanced precision version of the simulator for in-line single and
double pairs of future satellite mission scenarios. Error sources with a priori known frequency behavior are
accessed via stochastic modeling. This is achieved by using the information contained in the a posteriori residuals
in order to construct the appropriate covariance matrix of the observations and in a second run stochastically assess
the stationary noise of the laser and accelerometer instruments. Alternatively, empirical parameterization is also
engaged in the processing routine in order to minimize the effect of the propagated noise into the solutions and the
results are compared with the stochastic modeling. At last, temporal aliasing errors are mitigated by applying the so
40
called “Wiese approach” in our simulations. According to this approach, low resolution gravity field solutions are
estimated at short time intervals and in a next step combined with the full resolution mean field.
Glacial ice effect on the geoid
J. Huang1, M. Véronneau1, J. A. Dowdeswell2, T. J. Benham2 , D. O. Burgess3,and R. Forsberg4
1
Canadian Geodetic Survey, SGB, Natural Resources Canada , E-mail: [email protected]
2
Scott Polar Research Institute, University of Cambridge, UK
3
Geological Survey of Canada, Natural Ressources Canada
4
National Space Institute (DTU-Space), Denmark
Abstract: Glaciers can be found on high continental mountains, in the northern polar region (e.g., Ellesmere Island,
Greenland) and in Antarctica. Driven by the studies and monitoring of climate change, digital ice thickness models
have been developed for a number of well-studied glaciers. These models provide the data for estimating static
glacial ice effect on the geoid and its modelling. Within the computation area of the Canadian gravimetric geoid
model, glaciers are located in Alaska, USA, the Canadian Rockies, Northern Canada, and Greenland. In order to
understand the effect of glacial ice on the geoid, we studied two glaciers for which we have available ice thickness
models: Greenland Ice Sheet and Devon Ice Cap on Devon Island in Northern Canada. The former is massive and
covers an area of 1,833,900 km2. It has an average ice thickness of 1450 m with a maximum of 3293 m. The latter
covers a much smaller area of 12,000 km2. The ice cap has a maximum thickness of 776 m and an average
thickness of 263 m. The Greenland Ice Sheet and Devon Ice Cap represent two different scales of glaciers on Earth.
In this paper, we discuss the method of estimating glacial ice effect on the geoid and present the results for the two
glaciers.
Russian-Finnish Comparison of five absolute gravimeters at four different sites in
2013
J. Mäkinen1, R.A. Sermyagin 2, I.A. Oshchepkov 2, A.V. Basmanov 2, A.V. Pozdnyakov 2, V.D.Yushkin 3, Yu.F. Stus 4, D.A. Nosov 4
1
2
Federal Scientific Research Center of Geodesy, Cartography and SDI , Moscow, Russia (TsNIIGAiK)
3
4
Finnish Geodetic Institute, Masala, Finland (FGI)
Sternberg Astronomical Institute , Lomonosov Moscow University, Moscow, Russia (SAI MSU)
Institute of Automation and Electrometry , Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Abstract: In June-July 2013, a comparison of five absolute gravimeters was conducted at four sites in Russia. The
gravimeters in question were the FG5X-221 of the FGI, the FG5-110 and GBL-M 002 of the TsNIIGaiK,
GABL-PM of the IAE, and GABL-M of the NIIMorGeofizika (Murmansk, Russia). The three last-mentioned are
field-type portable gravimeters made by the Institute of Automation and Electrometry in Novosibirsk. The
comparison was conducted at four sites: in Pulkovo and in Svetloe near St. Petersburg, at the TsNIIGaiK laboratory
in Moscow, and in Zvenigorod near Moscow. At the TsNIIGAiK site and in Zvenigorod two piers were used, such
that altogether six stations were occupied. The FG5X-221 provides a tie to the International Comparison of
Absolute Gravimeters (ICAG-2013) in Luxembourg in November 2013. We present the comparison results and
discuss the performance characteristics of the different gravimeters.
41
The effect of helium emissions by a superconducting gravimeter on the rubidium
clocks of absolute gravimeters
Jaakko Mäkinen, Heikki Virtanen, Mirjam Bilker-Koivula, Hannu Ruotsalainen, Jyri Näränen, Arttu Raja-Halli
Finnish Geodetic Institute, Masala, Finland (FGI)
Abstract: Recently, large offsets in the frequency of rubidium clocks of absolute gravimeters have been reported,
due to contamination by helium from a superconducting gravimeter that shares the same laboratory space. We give
an account of the calibration histories of the rubidium clocks of the absolute gravimeters JILAg-5 (1987–2003),
FG5-221 (2003–2013) and FG5X-221 (2013–) of the FGI. Since 1995, they have been stationed (when not in field
work) in the Metsähovi gravity laboratory, about 4 meters from the superconducting gravimeter GWR TT020, in a
separate room. We analyze the influence of helium emission on the evolution of the frequency offsets of the clocks.
During the installation of a new superconducting gravimeter GWR Dual OSG 073 in January-February 2014 and
the ensuing large helium emissions we monitored the response of the rubidium clock of the FG5X-221 continuously.
In eight days, the clock frequency increased by 5 parts in 109. Such an offset (if not corrected for in the data
processing) would cause an offset of 10 µgal in observed gravity.
Airborne gravity across New Zealand;
Jack McCubbine1, Euan Smith1, Matt Amos2, Rachelle Winefield2, Fabio Caratori Tontini3
1
Victoria University of Wellington, School of Geography, Environment and Earth Sciences, Wellington,
New Zealand
2
Land Information New Zealand, National Geodetic Office, Wellington, New Zealand
3
GNS Science, Lower Hutt, New Zealand
Land Information New Zealand has recently completed a national airborne gravity survey over New Zealand for
the first time. The aim of the programme is to determine gravity anomalies at a 10 kilometre wavelength and
thereby compute a national quasigeoid with at least 3 centimetre accuracy. The airborne gravity data consist of a
uniform set of measurements that cover the whole of New Zealand which includes shallow coastal areas and rough
topography that have previously been extremely difficult to survey. Over 50,000 line-kilometres of surveying
were completed in two campaigns during August - October 2013 and February – April 2014. The key steps taken in
the data collection and reduction will be outlined along with preliminary results and error analysis.
The use of the A10-020 absolute gravimeter for the modernization of gravity
control in Poland
Jan Krynski, Przemyslaw Dykowski
Institute of Geodesy and Cartography, 27 Modzelewskiego St., Warsaw, Poland
E-mail: [email protected]; [email protected]
42
Abstract: Currently the A10 gravimeter is becoming a well recognized tool for various purposes, in particular for
modernization and maintenance of gravity control. It allows rapid determination of gravity with high accuracy in
various field conditions. Time series of gravity surveyed with the outdoor free-fall gravimeter A10 No 020 of the
Institute of Geodesy and Cartography at the test network in Borowa Gora Geodetic-Geophysical Observatory
starting from October 2008 proves that the A10-020 provides high quality measurements in laboratory as well as in
field conditions. It also shows high sensitivity of the gravimeter to local, regional and global hydrological changes
well correlated with GLDAS hydrological model.
In 2009–2010 the A10-020 gravimeter was successfully used for re-measurement of the Finnish First Order Gravity
Network. In the years 2011–2013 it was also used for re-measurement of gravity control of Denmark, Sweden and
Norway. Since the beginning of 2012 the A10-020 was incorporated into the modernization of the Polish gravity
control. Absolute gravity measurements were performed on 168 field stations exhibiting almost homogeneous
coverage of Poland. At each station the measurements with the A10-020 in at least two separate setups were
performed to make a on-spot verification of the collected data. Gravity surveys were performed in various seismic,
meteorological conditions as well as on stations of various types of monumentation.
During the course of the project regular monthly measurements were conducted at three gravity station at the
Borowa Gora Geodetic-Geophysical Observatory. Also 4 metrological calibrations were performed alongside with
the participation of the A10-020 in the international, regional and local absolute gravimeter comparison campaigns.
All collected data allowed to evaluate the suitability of the A10-020 gravimeter for the modernization of the gravity
control in Poland.
Release 3 of the GRACE gravity solutions from CNES/GRGS
Jean-Michel Lemoine1, Sean Bruinsma1, Pascal Gégout2, Richard Biancale1, and Stéphane Bourgogne3
1
CNES/GRGS, Toulouse, France ([email protected])
2
GET/UMR5563, Observatoire Midi-Pyrénées, Toulouse, France
3
Géode&Cie, Toulouse, France
Abstract: The GRACE mission, already more than 11 years in operation, has provided a large-scale vision of the
temporal gravity variations occurring on the Earth’s surface.Using the reprocessed Level-1B “v2” data, the
CNES/GRGS team has done a full reiteration of the GRACE and LAGEOS data processing based on upgraded data,
models and inversion procedures. This new release of the CNES/GRGS GRACE gravity solution, named “Release
3” or “RL03”, is now available and easily downloadable from the GRGS web site.
It features, in addition to using the new L1B-v2 data:
- an improved a priori gravity model, closely following the actual gravity variations already observed by
GRACE,
- the use of FES2012 ocean tide model,
- the use of the atmospheric dealiasing fields ECMWF ERA-interim (every 3 hours),
- the use of the oceanic dealiasing fields TUGO (every 3 hours),
- some changes in the K-Band ranging and accelerometer parameterization,
- an inversion procedure using truncated Eigen values allowing (as it was already the case for RL02) a direct
interpretation of the gravity solutions without the need for additional filtering,
- an extension of the maximal degree of the time-variable parameters from 50 to 80.
The CNES/GRGS RL03 solutions will be compared with the RL05 solutions from CSR, GFZ and JPL, focusing
particularly on the areas of the Earth where the spatial resolution of the solutions is important and challenging as,
43
for instance, in the vicinity of the three major earthquakes of Sumatra, Maule and Tōhoku.
What uses in today’s research for non-superconducting gravimeter observations
in Earth Tides modeling?
Jean-Pierre Barriot1,2 and Bernard Ducarme2,3
1
Geodesy Observatory of Tahiti (French Polynesia, [email protected])
2
International Center for Earth Tides
3
Catholic University of Louvain (Belgium)
Abstract: Over the past 15 years, superconducting gravimeters have dominated the research on Earth Tides. We
examine in this communication the role of other instruments like water tubes, inclinometers, pendulums, etc.. in
today’s research about Earth tides and geodynamical modeling.
Website: www.bim-icet.org
Evaluation of groundwater storage changes in Horqin Sandy Land (China) by
using GRACE
Jian-Di FENG, Zheng-Tao WANG, Wei-Ping Jiang, Neng-Fang CHAO and Yao-Dong QIU
School of Geodesy and Geomatics, Wuhan University, China,
[email protected]; [email protected]; [email protected] ; [email protected]; [email protected]
Abstract: The Horqin Sandy Land (~50600km2), located in western part of northeastern China (119~124◦E,
42◦20’~44◦20’N), is the biggest sandy land in China. Once covered with rich grassland vegetation and in some
parts with forests, the Horqin Sandy Land is now considered to be in the agro-pastoral transitional zone, suffering
severe desertification since the mid-1970s primarily due to long-term overgrazing, estrepement and the abuse of
water resources. Based on 90 months (July, 2003-December, 2010) of time-variable gravity field from the Gravity
Recovery and Climate Experiment (GRACE), data of Global Land Data Assimilation System (GLDAS) and
ground-based measurements, we estimate groundwater storage changes in Horqin Sandy Land. In this paper, soil
moisture and snow water equivalent are simulated by GLDAS, and the groundwater observations are derived from
5 national monitoring wells set in the Horqin Sandy Land. The soil moisture and snow water equivalent are used to
isolate groundwater storage from total water storage change (TWSC) of GRACE, and the observations of
monitoring wells are used as the comparative information. Besides, in order to estimate the result of GRACE
TWSC, we compared it with TWSC of CPC hydrological model. We find that the Horqin Sandy Land is losing
water at a rate of 40mm/yr equivalent water height, and the Horqin Sandy Land lost 26.67mm/yr of groundwater
during the 90-month period. Average groundwater depth changes from the monitoring wells over the same period
also showed a continuously decreasing tendency, at a rate of 266mm/yr. Taken into account the soil porosity (11.5%)
in Horqin Sandy Land, the rate of groundwater depletion estimated from well measurements is converted into
30.59mm/yr equivalent water height, which is consistent with the result of GRACE.
Keywords: GRACE; GLDAS; Horqin Sandy Land; Groundwater Storage Depletion
44
Towards a new best estimate for the conventional value of W0
L. Sánchez1, R. Čunderlík2, N. Dayoub3, K. Mikula2, Z. Minarechová2, Z. Šíma4, V. Vatrt5, M. Vojtíšková5,
1
2
Deutsches Geodätisches Forschungsinstitut (DGFI), Munich, Germany,
Department of Mathematics and Descriptive Geometry, Faculty of Civil Engineering, Slovak University of Technology in Bratislava,
Slovakia
3
Department of Topography, Faculty of Civil Engineering, Tishreen University, Latakia, Syria
4
5
Astronomical Institute, Academy of Sciences, Prague, Czech Republic
Geographic Service of the Czech Armed Forces, Military Geographic and Hydrometeorologic Office, Dobruška, Czech Republic
Abstract: At present, the most commonly accepted W0 value corresponds to the best estimate available in 2004, i.e.
62636856 m2s-2. However, recent computations based on the latest Earth’s surface and gravity field models shows
a clear offset from this W0 by about -2 m2s-2. According to this, in the frame of the Working Group on Vertical
Datum Standardisation, four different teams working on the computation of a global W0 value were brought
together to calculate a new best estimate of W0 and to outline the conventions needed to guarantee the reliability
and repeatability of its realisation. This new W0 value shall be introduced as the global height reference level, as a
defining parameter for a new geodetic reference ellipsoid, and as a reference value for the estimation of the
constant LG (defining the transformation between Terrestrial Time and Geocentric Coordinate Time). This
contribution provides a status report of the achievements oriented to the introduction of the new W0 value as a
formal IAG geodetic convention.
Renaissance of the torsion balance measurements
Lajos Volgyesi
Budapest Univ. of Technilogy and Economics
[email protected]
Abstract: In the XX century, a large amount of torsion balance measurements have been carried out around the
world, and large oil deposits have been found e.g. in Iran and in Texas. The torsion balance measurements still
provide a good opportunity to detect the lateral underground mass inhomogeneities and the geological fault
structures using the so called edge effects in gravity gradients. There is a possibility to determine the fine structure
of the gravity field too based on the gravity gradients.
In the XX century almost 60000 torsion balance measurements were made in Hungary mainly for geophysical
purposes. Only the horizontal gradients were used for geophysical prospecting, the curvature gradients measured by
torsion balance remained unused. However, using these curvature gradients, precise deflection of the verticals can
be calculated and using astronomical leveling the fine structure of geoid can be derived. In our test area a few
centimeters accuracy geoid was determined based on the curvature gradients.
In our study a claim was emerged to make additional new torsion balance measurements, so taking advantages in
today's modern new technical opportunities we reconstructed and modernized the older instruments, and new field
measurements were performed.
45
An Airborne Gravimetry Test of SGA-WZ in Greenland
Lei Zhao1,2,*, Kaidong Zhang1, Meiping Wu1, Rene Forsberg2, Arne Vestergaard Olesen2
1
College of Mechatronics Engineering and Automation, National University of
Defense Technology, Changsha 410073, Hunan, China;
E-Mails: [email protected] (M.W.); [email protected] (K.Z.)
2
National Space Institute, Technical University of Denmark, Copenhagen Ø, Denmark;
*
Author to whom correspondence should be addressed; E-Mail: [email protected];
Abstract: Airborne gravimetry is one of the most important ways for gravity data collection over large areas with
mGal accuracy and a spatial resolution (half wavelength of cut-off frequency) of several kilometers. In August
2012, a flight test was carried out to assess repeatability and accuracy of a new airborne gravimeter named
SGA-WZ in Greenland. There were four repeated flights in the test: two south-north flights were over the eastern
coast of the island and the other two lines with drastic changes in longitude were over southern mountain areas. The
flying altitude was about 360m above sea-level and the average flying speed was about 250 km/h. In the paper, A
160s length finite impulse response filter (FIR), corresponding to a spatial resolution of 6 km, is designed to post
process the measuring data. The mean standard deviation of two south-north flights is less than 6 mGal. Comparing
the upward continuation result of surface data, the mean difference for these flights is no more than 6 mGal.
However, both of the results for east-west flights are not good as the south-north flights. It is expected to obtain
better result if more refined filters are designed in future.
Keyword: Airborne gravimetry, Airborne gravimeter, Finite impulse response filter (FIR), SGA-WZ
De-correlation of two low-low Satellite-to-Satellite tracking pairs according to
temporal aliasing
M. Murböck, R. Pail
Technische Unversität München, Institute of Astronomical and Physical Geodesy, München, Germany
Abstract: The monitoring of the temporal changes in the Earth’s gravity field is of great scientific and societal
importance. Within several days a homogeneous global coverage of gravity observations can be obtained with
satellite missions. Temporal aliasing of background model errors into global gravity field models will be one of the
largest restrictions in future satellite temporal gravity recovery. The largest errors are due to high-frequent tidal and
non-tidal atmospheric and oceanic mass variations. Having a double pair low-low Satellite-to-Satellite tracking
(SST) scenario on different inclined orbits reduces temporal aliasing errors significantly. In general temporal
aliasing effects for a single (-pair) mission strongly depend on the basic orbital rates (Murböck et al. 2013). These
are the rates of the argument of the latitude and of the longitude of the ascending node. This means that the
revolution time and the length of one nodal day determine how large the temporal aliasing error effects are for each
SH order. The combination of two low-low SST missions based on normal equations requires an adequate
weighting of the two components. This weighting shall ensure the full de-correlation of each of the two parts.
Therefore it is necessary to take the temporal aliasing errors into account. In this study it is analyzed how this can
be done based on the resonance orders of the two orbits. Different levels of approximation are applied to the
de-correlation approach. The results of several numerical closed-loop simulations are shown including stochastic
modeling of realistic future instrument noise. It is shown that this de-correlation approach is important for
46
maximizing the benefit of a double-pair low-low SST mission for temporal gravity recovery.
Next Generation Satellite Gravimetry Mission Study (NGGM-D)
M. Murböck1, Th. Gruber1, M. Baldesarra9,P. Brieden3, I. Daras1, K. Danzmann4,5, B. Doll8, D. Feili10,
F. Flechtner7, J. Flury3, G. Heinzel4,5, S. Iran-Pour2, J. Kusche6, M. Langemann9, A. Löcher6, J. Müller3,
V. Müller4,5, M. Naeimi3, R. Pail1, J.-C. Raimondo7, J. Reiche4,5, T.Reubelt2, B. Sheard4,5, N. Sneeuw2, X. Wang8
1
Institut für Astronomische und Physikalische Geodäsie, Technische Universität München,Germany
2
Geodätisches Institut, Universität Stuttgart, Germany
3
Institut für Erdmessung and Centre for Quantum Engineering and Space-Time Research, Leibniz Universität Hannover, Germany
4
Max-Planck-Institut für Gravitationsphysik, (Albert-Einstein-Institut), Hannover & Golm
5
Institut für Gravitationsphysik, Leibniz Universität Hannover, Germany
6
Institut für Geodäsie und Geoinformation, Universität Bonn, Germany
7
Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Germany
8
SpaceTech GmbH Immenstaad, Germany
9
Astrium GmbH - Satellites, Friedrichshafen, Germany
10
TransMIT Gesellschaft für Technologietransfer, Giessen, Germany
Abstract: The main goal of this project is to develop an advanced mission concept for long term monitoring of
mass variations in the system Earth in order to improve our knowledge about the global and regional
water cycle (with the components continental hydrology, ocean, ice, atmosphere) as well as about processes of the
solid Earth. In times of global change this is needed to make more realistic predictions of system Earth parameters
on the basis of models derived from these observations. While geometric observation concepts like remote sensing
by optical and microwave techniques mainly observe changes at the Earth surface, gravimetric methods are the
only measurement technique, which is sensitive to mass variations. Because of the complementarity of gravimetric
and geometric observation concepts significant synergies and added value for the understanding of global processes
can be obtained. Starting from the existing concepts of the GRACE and GRACE-FO (Follow-On) missions,
sensitivity and spatial resolution shall be increased, such that also smaller scale time variable signals can be
resolved, which cannot be detected with the current techniques. For such a mission new and significantly improved
observation techniques are needed. This concerns in particular the measurement of inter-satellite distances, the
observation of non-gravitational accelerations and the configuration of the satellite orbits or of a constellation of
satellites. These new components and their complex interactions form the basis for a new space based observation
concept for mass variations in system Earth. The German Aerospace Center (DLR) funded a preparatory study in
order to develop a mission concept for a next generation gravity field mission. The study is coordinated by
Technical University Munich and incorporates all major players in the field of satellite gravimetry in Germany. By
joining scientific, technological and industrial expertise the resulting mission concept shall form the baseline for a
potential and realistic mission proposal for a next Earth Explorer Mission by the European Space Agency. The
paper presents the proposed mission concept resulting from this study.
Regional gravity field modeling using GOCE data: regularization issues
Majid Naeimi and Jakob Flury
Institute of geodesy, University of Hanover, Germany
47
Abstract: We present regional gravity field solutions using GOCE observations in several areas. The space
localizing spherical radial base functions are used for the representation of the gravitational field. Since the normal
equations associated to such regional modeling are strongly ill-posed, a meaningful solution must be obtained by
means of a proper regularization approach. We compare four different methods for the choice of the regularization
parameter. These methods are: (1) the variance component estimation (VCE), (2) the generalized cross validation
(GCV), (3) the L-curve criterion and the Parameter-signal-correlation (PSC). Two months of calibrated GOCE
gravity gradients (Txx, Txx and Tzz) are used for the regional modeling. For the validation of the results, we used
the recent GOCO03s geopotential model as the pseudo-true field and estimated the RMS of geoid differences for
our regional solutions over the target areas. In addition, we also assessed our regional solutions using a set of
GOCE gravity gradients (Txz) which are not used in the modeling. Thus our results are validated against an
independent set of data. The results indicate that the L-curve and the PSC methods provide equivalent results and
outperform the other two methods. We also show that the regional solution using GOCE data provides remarkably
better solutions (within the measurement bandwidth of GOCE) compared to any pre-GOCE model such as
EGM2008.
Airborne gravity for an improved New Zealand quasigeoid
Matt Amos1, Jack McCubbine2, Rachelle Winefield1, Euan Smith2, Fabio Caratori Tontini3
1
Land Information New Zealand, National Geodetic Office, Wellington, New Zealand
2
Victoria University of Wellington, School of Geography, Environment and Earth Sciences, Wellington, New Zealand
3
GNS Science, Lower Hutt, New Zealand
Abstract: Land Information New Zealand (LINZ) is midway through a project to improve the accuracy of the
quasigeoid-based New Zealand Vertical Datum 2009 to 3cm in developed areas.
A key component of this project has been the collection of an airborne gravity dataset across New Zealand. The
more than 50,000 line-kilometres of airborne data will be used to fill the spectral gap between global geopotential
model-derived gravity anomalies and the relatively dense, but spatially sporadic, terrestrial gravity data.
This study presents results from the gravity survey and compares them with terrestrial data and high degree/order
global geopotential models.
Sub-crustal stress induced by mantle convection from gravity data
Mehdi Eshagh1, Robert Tenzer2
1
Department of Engineering Science, University West, Trollhättan, Sweden
2
The Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road,
Wuhan, 430079 China
Abstract: The spherical harmonic expression of the gravimetric Moho model developed based on the Vening
Meinesz-Moritz’s inverse problem of isostasy is similar to that of sub-crustal stress due to the mantle convection.
We use this similarity and develop a new mathematical model for expressing the sub-crustal stress in terms of
harmonics of the gravimetric Moho model. Due to the divergence of the spherical harmonic expression of the
sub-crustal stress components, we propose a new method for computing the stress without divergence problem and
we call it the S function with numerical differentiation. The S function is expressed in terms of spherical harmonics,
48
not its derivatives, and the harmonics of Moho model and topographic heights from which the stress can be
computed numerically. We will concentrate in five areas of Hawaii, Himalaya and Tarim Basin, Japan, Island and
South America for presenting our numerical results and interpretations.
Keywords: crust, gravity, mantle convection, Moho interface, stress
Software Development for Relative Gravimetry towards Turkish Height System
Modernization
Mehmet Simav1, Hasan Yildiz2
1,2
General Command of Mapping, Geodesy Department, TR-06100, Dikimevi, Ankara, Turkey.
1
[email protected], [email protected].
Phone: 0090 312 595 2246, Fax: 0090 312 320 1495
Abstract: Turkish Height System Modernization Project aims to perform new terrestrial gravity measurements
throughout the country at 5′ x 5′ resolution in order to improve the accuracy of Turkish gravimetric geoid model. A
software system is needed (i) to store and manage the steadily growing number of relative gravity observations and
their respective metadata, (ii) to reduce and process the data using internationally accepted procedures, protocols,
equations and parameters. This study describes the preliminary version of the software consisting of a relational
database and a MATLAB based graphical user interface (GUI) running on Windows operating systems. Prior to the
database setup, an exchange format is defined for the groups to upload the relative gravity readings to the database.
The database consists of five main and six child tables, related to each other by sets of matching keys, which hold
information about gravity stations (name, code, coordinates, method of positioning etc.), gravimeters (type, serial
number, calibration parameters etc.), institutions & operators (name, contact information etc.), gravity readings and
reductions (raw readings, observation time, tide correction, drift corrections etc.), and processed gravity values
(gravity values, errors etc.). The GUI has lots of tools and functionalities such as management, monitoring,
computation and statistical tools for the data reduction, network adjustment, vertical gravity gradient estimation,
gravimeter calibration and long term drift computation. The preliminary version of this software will be introduced
and some of its applications will be demonstrated.
Gravity field from combination of GRACE and SLR data
Minkang Cheng
Centre for Space Research, University of Texas at Austin
Austin, Texas 78759-5321, USA, [email protected]
Abstract: Study has shown that the C20 must be replaced by the SLR derived C20 in the statistic and temporal
GRACE gravity field for better orbit fit and study of the mass transport within earth system, in particular mass
changes of polar ice sheets. We present a mean gravity field with degree and order of 120, and a time series of
monthly solutions with a full degree and order 60 gravity field estimated from combination of the GRACE and
SLR data. In combination with SLR data, the GRACE data is down weighted with a factor of 0.45, the estimate of
C20 and geocenter (equivalent to degree one geopotential coefficients) are based on the SLR data only from fives
geodetic satellites, including LAGEOS-1 and -2, Starlette, Stella and Ajisai. The combination of GRACE and SLR
data enhances the separation of the rate of J2 with the effects of higher degree (> 6) zonals, and improves the
49
estimating of the resonance coefficients of order 15, 30 45 and 60. Detail analysis will be presented in this paper.
Post-glacial rebound signal observed with repeated absolute gravimetry in
Finland
Mirjam Bilker-Koivula1, Jaakko Mäkinen1, Hannu Ruotsalainen1, Jyri Näränen1, Ludger Timmen2, Olga Gitlein2, Fred Klopping3,
Reinhard Falk4
1
Finnish Geodetic Institute (FGI), P.O.Box 15, 02431 Masala, Finland
2
Institute für Erdmessung (IfE), Hanover, Germany
3
National Oceanic and Atmospheric Administration (NOAA), USA. Currently at Micro-g LaCoste, USA
4
Bundesamt für Kartographie und Geodesie (BKG), Frankfurt am Main, Germany
Abstract: Postglacial rebound (PGR) has been ongoing in Fennoscandia since the last ice age. Uplift rates have
been observed with a variety of techniques, such as levelling, tide gauges and GPS. In the center of the uplift area
observed vertical velocities are 1 cm/year. Here, we show the result of repeated absolute gravity measurements in
Finland.
As part of the Nordic Absolute Gravity Project, absolute gravity has been observed at seven sites in Finland for at
least 3 times between 2003 and 2012. The measurements were carried out with the FG5-221 gravimeter of the FGI
and the FG5-220 gravimeter of the IfE. Here, we also utilize older measurements performed before this period.
This includes early measurements made with the IMGC gravimeter of the Instituto di Metrologia “G. Colonnetti”
(IMGC) in 1976 and with the GABL gravimeter of the Soviet Academy of Sciences (ANSSSR) in 1980.
Measurements were also made with the FG5-111 and FG5-102 gravimeters of NOAA in 1993 and 1995 and with
the FG5-101 gravimeter of BKG in 2000. Between 1988 and 2002 the FGI performed repeated measurements with
the JILAg-5 gravimeter. We estimate trends trough the gravity time series and compare these with trends obtained
from other sources, such as GIA models and observations of vertical motion.
The absolute gravity time series clearly show the postglacial rebound signal. Trends estimated from the time-series
vary between -2.0 and +0.2 µGal /yr. At most stations the found rates agree well with rates predicted from
observations of PGR vertical motion and/or GIA models. However, at some sites there are discrepancies. These
may be due to e.g. seasonal and inter-annual non-PGR variation in gravity, possible offsets between instrument
types, and an insufficient amount of data.
GOCE data as grids of gravity gradients at satellite altitude
Mirko Reguzzoni, Andrea Gatti, Federica Migliaccio, Fernando Sansò
DICA, Geodesy and Geomatics Area, Politecnico di Milano, Italy
Abstract: The GOCE mission ended in November 2013 after collecting high quality gravity information that is now
contributing to increase our knowledge of the Earth system. This information is basically distributed in the form of
spherical harmonic coefficients from which different functionals of the gravity field can be synthesized. Original
and filtered gravity gradients along the orbit are provided to the users too. In this work we computed an additional
GOCE product consisting in high resolution grids of gravity gradients in a locally oriented East-North-Up reference
frame at satellite altitude. The idea behind this product is to deliver a GOCE-only dataset that is easier to use than
the original observations along the orbit and possibly carrying higher local information than spherical harmonic
50
global models. These grids are computed by means of the space-wise approach that has been adapted to obtain
locally-oriented grids. Two are the main modifications of the original method scheme. One is the use of a different
cloud of points for almost each grid knot instead of using a priori defined equiangular data patches; this strategy of
data partitioning, jointly with a signal covariance modelling based on locally adapted degree variances, allows to
better estimate the local characteristics of the gravity signal. The other is the application of a sort of along-track
whitening filter to reduce the time correlation of the noise and leave untouched the highest frequencies of the signal.
For this reason this filter well couples with the previously mentioned new data partitioning. Note that the
along-track Wiener filter, originally designed for the space-wise approach, is still used for the recovery of the
medium frequencies, while the lowest ones mainly come from the SST data analysis.
Space-wise grids of gravity gradients based on data acquired before lowering the GOCE orbit and properly
under-sampled to reduce the processing time are here presented and compared with other GOCE global gravity
solutions.
The International Geoid Service: present status and future perspectives
Mirko Reguzzoni, Giovanna Sona
DICA, Geodesy and Geomatics Area, Politecnico di Milano, Italy
Abstract: The International Geoid Service (IGeS) was established in 1992 as a working arm of the International
Geoid Commission and then it became an official IAG service. Since 2003, IGeS is a member of IGFS, together
with BGI, ICGEM, ICET, IDEMS. It has two centres, the main one is located at the Department of Civil and
Environmental Engineering of Politecnico di Milano, Italy, the other one is at NGA, USA.
The main task of IGeS is to collect, validate and redistribute local and regional geoid estimates worldwide,
differently from ICGEM which is mainly devoted to global geoid models. Just to give some numbers, there are
presently 34 geoid estimates on IGeS website; at the beginning of this year, 36 requests for acquiring new geoid
estimates were sent to authors (6 new estimates were included in the database, 4 will come soon, further requests
will be sent out in the near future). Apart from that, software tools for geoid computation are also available on the
website which is continuously updated (in particular a new web interface has been recently implemented). Other
research tasks concern the study and the assessment of new methods for geoid estimation. The service has also an
educational mission by organizing international schools on geoid determination, with the latest being held in
October 2013 at Universidad Técnica Particular de Loja, Ecuador. In this sense, the service provides support to
researchers in computing regional/local geoid estimates, especially for those coming from developing countries.
Finally it disseminates scientific publications on geoid/gravity applications through Newton’s Bulletin (a journal
issued since 2003 and merging IGeS and BGI Bulletins) and lecture notes for geoid computation.
Future plans are in the line of the present day activities. The possibility of validating local/regional existing geoid
estimates with satellite-only global geopotential models and DTM will be deeply investigated, with the aim of
detecting possible low-medium frequency distortions that could be present in previously used global geopotential
models, e.g. EGM2008. New software for geoid estimation will be made available to users, with a particular
interest to new methods for covariance modelling to be used in a collocation approach. Projects for local/regional
geoid estimate will be proposed and pursued; among them, we mention here the one for the geoid computation in
the Mediterranean area in co-operation with BGI and the Thessaloniki University and the one for collecting gravity
data to improve the geoid over the Alpine area. As for the organization of the international geoid school,
Universities of the Dominican Republic, Mexico and Jordan have proposed to organize it the next year.
Furthermore, different formats will be studied in order to have schools on a broader set of possible topics in
51
physical geodesy.
Viscosity of the mantle inferred from land uplift rate and three reduced gravity
field models in Fennoscandia
Mohammad Bagherbandi1,2 , Lars E. Sjöberg1
1
2
Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
Department of Industrial Development, IT and Land Management, University of Gävle, SE-80176 Gävle, Sweden
Email: [email protected]
Abstract: One potential application of post-glacial rebound is to determine the viscosity of the mantle. In this study
we use a geodetic method with CRUST1.0 and Vening Meinesz-Moritz crustal thickness models (Sjöberg 2009 and
Bagherbandi et al. 2013). We derive the viscosity of the mantle from the land uplift rate and three different
reduced gravity field models. The reduced models are: a) a truncated gravity model according to special harmonic
window (Sjöberg and Bagherbandi 2013), b) crust corrected gravity model c) a model reduced
for non-isostatic effects. In model “a)” the aim is to find a harmonic window, which fits the land uplift model in
an optimum way. In model b) the gravity field model is reduced by either a seismic or gravimetric crustal
thickness model. Finally, in model c) estimated disturbing gravity signals (non-isostatic effects) will be utilized.
Using above mentioned models in the central part of Fennoscandia the mean value of mantle viscosity is
obtained to about 0.36, 6 and 36×1022 Pa.s for models a and b and c, respectively.
Effect of the rock equivalent topography on the Moho geometry
Mohammad Bagherbandi1,2, Lars E Sjöberg2, Majid Abrehdary2 and Robert Tenzer3
1
Department of Industrial Development, IT and Land Management University of Gävle, SE-801 76 Gävle,Sweden.
2
Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden.
3
The Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics,
Wuhan University, 129 Luoyu Road, Wuhan, 430079 China
Abstract: We investigate the effect of heterogeneous crust structures (i.e., variable topographic height density),
which is not typically taken into consideration in classical isostatic models. Naturally, assuming a constant crustal
density will result in an error of the Moho determination because of a rock equivalent topography (RET)
assumption. This study present a novel approach to overcome this problem using topographic heights, which are
determined through a gravimetric-isostatic model. We demonstrate that this approach improves the quality of the
Moho depth estimation. We also shown that the bias between the real and isostatically compensated topography
varies from -382 to 596 mGal with a global standard deviation of 106 mGal. This gravity bias correspond to the
Moho correction term of -16 to 25 km, with a standard deviation of 4.6 km. It implies that the RET effect has a
significant role in compensating the topographic masses, especially at the medium to higher degree parts of the
gravity spectrum (approximately above degree 40 of spherical harmonics). This indicates that the isostatic models
formulated based on the topographic mass balance are equilibrium of the Earth’s crust that a high-degree spectrum
of the topography (say to degree and order 40) is not isostatically compensated by only the Moho geometry. A
possible explanation is that the isostatic mass balance within the crust cannot be fully attained by a varying depth of
52
compensation, especially at higher-degree part of the gravity spectrum.
Keywords: crust, gravity, isostasy, Moho, rock equivalent topography
Study and investigation for Behaviours of isotropic parts of the modified kernel
integral estimators
Mohsen Romeshkani* and Sahar Ebadi**
* K.N.Toosi Univ. Tech. Iran
*Email: [email protected]; **Email: [email protected]
Abstract: The Earth’s global gravity field modelling is an important subject in Physical Geodesy. Satellite gravity
gradiometry (SGG) is a space technique to measure the second-order derivatives of geopotential for this field, but
the measurements should be validated prior to use. The existing terrestrial gravity anomalies and Earth gravity
models (EGMs) can be used for this purpose. For this, we can use least-squares modification techniques to reduce
the contribution of far-zone gravity anomalies in validation of SGG data. This paper present the behavior of the
isotropic parts of kernels of the integral estimators for the second-order vertical-vertical (VV), vertical–horizontal
(VH) and horizontal–horizontal (HH) derivatives of the extended Stokes formula in the local north-oriented frame.
They are modified using biased, unbiased and optimum types of least-squares modification and deterministic
modifications (Molodensky, Vanicek-Kleusberg, Meissl, Heck and Grunningar, Featherstone, Wong and Gure).
These modified integral estimators are used to generate the VV, VH and HH gradients at 250 km level for
validation purpose of the SGG data. The isotropic parts of the kernels of the integral estimators are presented. The
significance of the far-zone gravity anomalies depends on these parts of the kernels. Plotting these isotropic
functions shows that whether the modification has been done successfully or not. Also, it can somehow give an idea
about the significance of the data being integrated and the cap size of integration.
Correlation analysis between the melting of the Eastern Tibetan Plateau glacier
and the change of Yangtze River water storage
Neng-Fang CHAO , Zheng-Tao WANG
School of Geodesy and Geomatics, Wuhan University, China
Abstract: Glacial melting in the Eastern Tibet Plateau plays a very important role in water storage variation of
Yangtze River basin that originates in this region. Coherence analysis between them is a challenging topic. Here we
use satellite laser altimetry and a global digital elevation model to monitor glacier thickness changes in the Eastern
Tibet Plateau during 2003-09. The mass balance for our entire study region was -2.31cm/yr. Simultaneously, we
based on gravity data of the Gravity Recovery and Climate Experiment (GRACE) satellite from 2003-09, inverted
and established time series of mass changes for Yangtze River Basin, estimated their average variation rate to be
0.532cm/yr. Furthermore, we associated hydrological model, used the water balance method, then average rate of
changes with deducting terrestrial water storage variation of the Yangtze River Basin is found to be 0.330cm/yr. As
a result, it is shown that glacial melting at Tibet Plateau contributes 14.3% of water storage variation in Yangtze
53
River basin, the correlation coefficient is -0.425, it means there is a significant negative correlation between them.
Key words: ICESat, SRTM, GRACE, Glacial Melting, Water Storage Variation, Correlation analysis
Evaluation of GOCE-based Global Geopotential Models versus EGM2008 and
GPS/Levelling data in Turkey
Nevin Betul Avsar1, Bihter Erol2, Senol Hakan Kutoglu1
1
Department of Geomatics Engineering, Bulent Ecevit University, Incivez 67100, Zonguldak, Turkey,[email protected],
[email protected]
2
Department
of
Geomatics Engineering, Istanbul
Technical
University, Ayazaga, Maslak 34469,Istanbul, Turkey,
[email protected]
Abstract: The Gravity field and steady-state Ocean Circulation Explorer (GOCE) announced end of itsmission in
mid-October 2013 was a milestone in Earth’s gravity field determination. SeveralGlobal Geopotential Models
(GGMs) have been published based on the data collected duringthe four-year mission of GOCE. This study focuses
on the performance of four differentgenerations of GOCE-based GGMs currently released in terms of the
differences betweenGGMs-derived and GPS/levelling geoid heights in absolute sense. In the study, a total of
7GOCE-based models (EIGEN_6C3stat, JYY_GOCE02S, ITG-GOCE02, GO_CONS_GCF_2_TIM_Release 1,
2, 3, and 4) were assessed and the results were compared with performance of EGM2008 in the evaluation area.
The accuracy of GGMs was
analyzed using the reference GPS/levelling network of the case study for Bursa located in the northwest of the
Anatolian peninsula. In the analysis, 433 GPS/levelling benchmarks after removing of the data, detected as
blunders, were used for evaluation of the global geoid models. The validation results show the superior
performance of the high resolution global combined model EIGEN_6C3stat among the evaluated models. Its fit
with GPS/levelling-derived geoid heights in the study area is at the level of 8.5 cm in terms of standarddeviations.
The fitting of ITG-GOCE02 and JYY_GOCE02S determined with a standarddeviation are 11.2, and 13.9 cm,
respectively.The results on the contribution of GOCE mission data to the representation of gravity field in Turkish
territory depending on theconsecutive releases of GOCE-based models are analyzed and interpreted in conclusions
of this study.
Keywords: GOCE, Global Geopotential Model, GPS/levelling, Geoid Height, Bursa
The DTU13 MSS (Mean Sea Surface) and MDT (Mean Dynamic Topography)
from 20 years of satellite altimetry
Ole Andersen, Lars Stenseng and Per Knudsen
Technical University of Denmark, DTU Space, 2800 Lyngby, Denmark.
Abstract: The DTU13MSS is the latest release of the global high resolution mean sea surface from DTU Space.
Two major advances have been made in order to release the new mean sea surface. The time series have been
extended to 20 years from 17 years for the DTU10 creating a multi-decadal mean sea surface for the first time.
Secondly, the DTU13MSS ingest Cryosat-2 LRM and SAR data as well as 1 year of Jason-1 geodetic mission, as
the Jason-1 satellite has been operating in geodetic mission as part it end of life mission since May 2012. This is a
54
fantastic new source of altimetric data which can be used to replace the older ERS-1 and GEOSAT geodetic
mission for the mean sea surface as the new data have far better range precision. Evaluation of the new MSS is
performed and comparison with existing MSS models is performed to evaluate the impact of these updates into
MSS computation.
The Global Gravity Field Model (DTU13) and evaluation in the Arctic Ocean
Ole Baltazar Andersen1, P. Knudsen1, L. Stenseng1, S. C. Kenyon, J. K. Factor, N. Markiel, S. Ingalls
1
DTU Space, Denmark
2
National Geospatial-Intelligence Agency, GIMG
Abstract: Since the release of the DTU10 global marine gravity field in 2010, the amount of geodetic mission
altimetry has nearly tripled [1]. The Cryosat-2 satellite have provided new altimetric data along its 369 day near
repeat since 2010 and since May 2012 the Jason-1 satellite has been operating in geodetic mission as part its end of
life mission and it continued in this until it was decommissioned in June 2013 Of equal importance is the fact that
the Cryosat-2 and Jason-1 are new generations of satellite altimeters offering increased range precision compared
with the ERS-1 and Geosat generation satellites. As range precision directly maps into gravity field accuracy this
should also significantly improve global marine gravity field modeling. The Cryosat-2 pre-launch specifications
indicated a factor of two in range precision compared with the older geodetic mission which in principle should
lead to a similar factor of two in gravity field modeling. The availability of particularly Cryosat-2 with its coverage
throughout the Arctic Ocean is a quantum leap forward for altimetric gravity field modeling in Polar Regions and in
this presentation we try to quantify the improvement in gravity field mapping – but globally but particularly in the
Arctic through comparison with highly accurate marine gravity observations.
Ellipsoidal Effects, Modelling and Technique Refinements in High Accuracy
Quasigeoid Computations
Otakar Nesvadba1, Petr Holota 2
1
2
Land Survey Office, Prague, Czech Republic, e-mail: [email protected]
Research Institute for Geodesy, Topography and Cartography, Zdiby, Prague-East, Czech Republic, e-mail: [email protected]
Abstract: The paper focuses on methodological and computational aspects associated with high accuracy
quasigeoid modelling. Accuracy demands driven by GNSS levelling applications are substantially taken into
consideration. The concept of the so-called gravimetric boundary value problem was used as the basis for the
determination of the disturbing potential from gravity disturbances. In the approach developed the Green’s function
constructed for the exterior of an oblate ellipsoid of revolution is essentially used for the solution of the problem.
The mathematical apparatus is constructed consistently. The idea of spherical approximation was avoided. This also
means that the kernel used for the integral representation of the solution is an ellipsoidal analogue to the so-called
Hotine-Koch function well-known in physical geodesy. Fundamental steps leading from an ellipsoidal harmonics
series representation of the kernel into its closed form expression are explained. Legendre elliptic integrals were
substantially used in the numerical evaluation of the kernel. Effects caused by the departure of the Earth’s surface
from the ellipsoid as well as oblique derivative effects associated with the structure of the boundary condition are
taken into account through successive approximations. Their construction follows the concept of analytical
55
continuation and was implemented by means of the apparatus related to an oblate ellipsoid of revolution. The
approach discussed in the paper was subjected to extensive numerical and computation tests. Terrestrial gravity,
levelling and GNSS data from the Czech Republic territory were used for this purpose. On this basis we have well
justified reasons to conclude that the results obtained and interpreted in terms of height anomalies or quasigeoid
heights achieve an accuracy level of one centimeter in most of the Czech Republic territory.
Hunting a 1 cm geoid in the land of fjords-Norway
Ove Christian Dahl Omang and Dagny Iren Lysaker
Norwegian Mapping Authority,Norway
HØNEFOSS; Post code: 350; E-Mail:[email protected] ; Tel: +47 32118279
Abstract: Deep fjords and high mountains do not help out in mapping the gravity field across Norway. The fjord,
seen as long scars through the mountainous western part of Norway, is as deep as 1300 m. This together with
mountains as high as 2500 m makes it difficult to achieve a 1 cm geoid.
The distribution of gravity data has mainly been on land with a spacing of approximately 3 - 5 km, with no gravity
data in the fjords. During the last few years some of the large fjords and lakes have been measured. These new
gravity measurements yield changes in the geoid of as much as 30 cm, locally improveing the fit to GPS/leveling
points.
To improve the quality of the gravity data we have updated their position and height to EUREF89 and the latest
Norwegian height system (NN2000), and outliers have been removed. However, the accuracy of the position may
still be as bad as 500 m, which may be critical in steep fjord areas.
The digital terrain model used in the geoid computation has been updated from a 5 km to a 1 km model, yielding
improvement of approximately 10% in fit to the GPS/leveling points. Our next step is to change the DTM to a
100 m model.
Another area of which has been investigated is modification of Stokes kernel. We have used a Wong-Gore
modification and by selecting the “best” truncation a 10% improvement in fit was achieved.
By applying these improvements we have managed to improve the standard deviation of the fit to GPS/leveling
points, covering the whole Norway, from originally around 6 cm down to 4.5 cm. In two smaller test areas, one is
around the Sognefjord while the other is in the flatter south eastern part of Norway, the fit to the GPS/leveling
points are down to 3.5 cm and 2.3 cm.
GOCE User Toolbox and Tutorial
Per Knudsen 1, Jerome Benveniste 2, and Team GUT 2
1
DTU Space, National Space Institute, Geodesy, Kgs. Lyngby, Denmark ([email protected])
2
ESA/ESRIN, Frascati, Italy
Abstract: The GOCE User Toolbox GUT is a compilation of tools for the utilisation and analysis of GOCE Level 2
products. GUT support applications in Geodesy, Oceanography and Solid Earth Physics. The GUT Tutorial
provides information and guidance in how to use the toolbox for a variety of applications. GUT consists of a series
of advanced computer routines that carry out the required computations. It may be used on Windows PCs,
UNIX/Linux Workstations, and Mac. The toolbox is supported by The GUT Algorithm Description and User Guide
and The GUT Install Guide. A set of a-priori data and models are made available as well. Recently, the second
56
version of the GOCE User Toolbox (GUT) was developed to enhance the exploitation of GOCE level 2 data with
ERS ENVISAT altimetry. The developments of GUT focused on the following issues: Data Extraction, Generation,
Filtering, and Data Save and Restore Without any doubt the development of the GOCE user toolbox have played a
major role in paving the way to successful use of the GOCE data for oceanography. The results of the preliminary
analysis carried out in this phase of the GUTS project have already demonstrated a significant advance in the
ability to determine the ocean’s general circulation. The improved gravity models provided by the GOCE mission
have enhanced the resolution and sharpened the boundaries of those features compared with earlier satellite only
solutions. Calculation of the geostrophic surface currents from the MDT reveals improvements for all of the
ocean’s major current systems.
http://earth.esa.int/gu The GOCE User Toolbox GUT is a compilation of tools for the utilisation and analysis of
GOCE Level 2 products. GUT support applications in Geodesy, Oceanography and Solid Earth Physics. The GUT
Tutorial provides information and guidance in how to use the toolbox for a variety of applications. GUT consists of
a series of advanced computer routines that carry out the required computations. It may be used on Windows PCs,
UNIX/Linux Workstations, and Mac. The toolbox is supported by The GUT Algorithm Description and User Guide
and The GUT Install Guide. A set of a-priori data and models are made available as well. Recently, the second
version of the GOCE User Toolbox (GUT) was developed to enhance the exploitation of GOCE level 2 data with
ERS ENVISAT altimetry. The developments of GUT focused on the following issues: Data Extraction, Generation,
Filtering, and Data Save and Restore Without any doubt the development of the GOCE user toolbox have played a
major role in paving the way to successful use of the GOCE data for oceanography. The results of the preliminary
analysis carried out in this phase of the GUTS project have already demonstrated a significant advance in the
ability to determine the ocean’s general circulation. The improved gravity models provided by the GOCE mission
have enhanced the resolution and sharpened the boundaries of those features compared with earlier satellite only
solutions. Calculation of the geostrophic surface currents from the MDT reveals improvements for all of the
ocean’s major current systems.
http://earth.esa.int/gut
Quality assessment of the new gravity control in Poland – first estimate
Przemyslaw Dykowski, Jan Krynski
Institute of Geodesy and Cartography, 27 Modzelewskiego St., Warsaw, Poland
E-mail: [email protected]; [email protected]
Abstract: The new gravity control in Poland is based on absolute gravity measurements. It consists of 28
fundamental stations and 168 base stations. Fundamental stations are located in laboratories; they are to be
surveyed in 2014 with the FG5-230 of the Warsaw University of Technology. Base stations are monumented field
stations; they were surveyed in 2012 and 2013 with the A10-020 gravimeter. They are the subject of the
presentation.
Besides absolute gravity measurements the vertical gravity gradient was precisely determined at all 168 base
stations. Nearly 350 single absolute gravity measurement setups and vertical gravity gradient determinations
performed provide valuable and comprehensive material to evaluate the quality of the established gravity control.
Alongside the establishment of the base stations of the gravity control multiple additional activities were performed
to assure and provide the proper gravity reference level. They concerned regular gravity measurements on monthly
basis with the A10-020 at three sites in Borowa Gora Geodetic–Geophysical Observatory, calibrations of
metrological parameters of the A10-020 gravimeter and scale factor calibrations of LCR gravimeters, participation
57
with the A10-020 in the international (ECAG2011, ICAG2013) and regional comparison campaigns of absolute
gravimeters, and local comparisons of the A10-020 with the FG5-230.
The summary of the quality assessment is best described by total uncertainty budget for the A10-020 gravimeter
determined on each of the 168 gravity stations.
Project of Space Advanced Gravity Measurements(SAGM)
Q. KANG, W.R, HU
National Microgravity Laboratory, institute of Mechanics, Chinese Academy of Science
([email protected]; [email protected] )
Abstract: The project is a concept research of gravity measurements based on low-orbit satellite-to-satellite
tracking technology, which was supported by Pre-research program of the Strategic Priority Research Program on
Space Science, Chinese Academy of Sciences started in 2009. The overall objectives of SAGM are to develop
SAGM satellites based on two co-orbiting drag-free satellites with laser ranging and to implement the high
precision of dynamic spatial resolution, which will be superior to GRACE. We anatomized the mission and the key
technologies of the prospective mission as follow:
(1) Monitoring and global / regional model research on Climate System and Earth System
(2) Gravity satellite system simulation and gravity-field recovery technology study
(3) Data processing, noise analysis
(4) Space laser and its technique of frequency stabilization and phase locking
(5) Pre-test system study for space laser interferometer
(6) Drag-free control and micro-propulsion technology study
(7) Satellite mission analysis and Requirements definition
The researches is to meet demands from future earth sciences research on gravity field and national requirement for
disaster defense and environment condition improvement, to drive the development of many techniques such as
space laser interferometry, drag-free control and high-precision accelerometer in china, and to implement the study
of the global impact of the gravity anomaly by the high-precision measurement of the earth gravity field.
Monthly gravity field model derived from GRACE Level1b data by modeling
non-conservative acceleration and attitude observation errors
Qiujie Chen1,2,4, Yunzhong Shen1,2, Houze Hsu3, Wu Chen4 , Xingfu Zhang5, Xiaolei Ju1
1
2
College of Surveying and Geo-informatics, Tongji University, Shanghai, PR, China
Center for Spatial Information Science and Sustainable Development, Shanghai, PR, China
3
State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics,
CAS, Wuhan, China, 430077
4
The Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong
5
Departments of Surveying and Mapping, Guangdong University of Technology, Guangzhou, 510006
Abstract: Many gravity field models have been developed from GRACE data, and the non-conservative
acceleration and attitude are used as error-free observations in deriving most of these models. However, the
58
non-conservative acceleration and attitude observations are certainly contaminated by observation errors, which are
not smaller enough to be neglected. For this reason, we further modify the short arc approach by modeling the
non-conservative acceleration and attitude observation errors in the observation equation. Then we develop the
monthly gravity field model complete to degree and order 60 using the GRACE RL02 data officially released by
Jet Propulsion Laboratory (JPL). This model is compared in terms of degree geoid errors and the temporal mass
change signals with the Tongji-GRACE01 model and the RL05 models officially released by the Centre for Space
Research (CSR), GeoForschungsZentrum (GFZ) and JPL, respectively, the results show that the noises of the new
developed model, including the north-south stripes, are apparently smaller than Tongji-GRACE01 model and the
RL05 models of CSR, GFZ and JPL.
Keywords: GRACE; Monthly gravity field model; Short arc approach; acceleration and attitude observations
Testing airborne gravity data in the large-scale area of Italy and adjacent seas
R. Barzaghi1, A. Albertella1, F. Barthelmes2, S. Petrovic2, M. Scheinert3
1
Politecnico di Milano, Milano, Italy.
2
Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ), Potsdam, Germany.
3
Technische Universität Dresden, Dresden, Germany.
Abstract: In 2012 the GEOHALO flight mission was carried out using the new German research aircraft HALO.
This mission was a joint project of several universities and research institutions from Germany, Switzerland and
Spain, led by the co-author (M.S.) as Mission PI. The German Aerospace Center (DLR) as the managing agency of
HALO provided all necessary ground facilities, so that all flights started and ended in Oberpfaffenhofen, Germany.
Considerable support was also given by Italian institutions and authorities. The surveyed zone covers the
Central-South part of Italy, roughly from latitude 36°N to 44°N. In this area, seven main tracks NW to SE were
surveyed having a spacing of about 40 km and an altitude of 3,500 m, complemented by an eighth track in an
altitude of 10,000 m. Four perpendicular cross tracks were also added.
Amongst the geodetic-geophysical equipment GEOHALO carried two gravimeters. In this presentation we will
focus on the GFZ instrument, a CHEKAN-AM gravimeter. The raw CHEKAN-AM data underwent a first,
preliminary analysis. The present investigation aims at defining the spectral properties and the level of accuracy
and precision of the observed gravity data. Preliminary comparisons with existing global geopotential models
showed the reliability of these observations. In this paper, some comparisons with gravity anomalies predicted from
Italian ground data are presented. The gravity field in the surveyed area as derived from ground data is propagated
to the aerogravity survey points and compared to the observed gravity anomalies. Upward continuation is
performed using the remove-restore approach and collocation. In this context, several global models are used to
model the low frequency component of the gravity signal, together with consistent average DTMs.
Further analyses have to be accomplished to strive for an optimal combination of the data gained by the two
gravimeters, to introduce the best GNSS solution of the flight trajectory, and to come up with a thorough error
analysis of the deduced gravity field quantities.
Estimating Geoid and Sea Surface Topography in the Mediterranean Sea
R. Barzaghi1, A. Albertella1, N. E. Cazzaniga1, S. Bonvalot2 , S. Bruinsma3,
M.F. Lequentrec-Lalancette4 , I.N. Tziavos5, G.S. Vergos5, V.N. Grigoriadis5
1
DICA, Politecnico di Milano, Milano, Italy
59
2
OMP/GET/IRD, Toulouse, France
3
CNES/GRGS, Toulouse, France
4
SHOM/GRGS, Brest, France
5
Aristotle University, Thessaloniki, Greece
Abstract: A detailed estimate of the geoid can be profitably combined with a Mean Sea Surface (MSS) inferred
from radar altimeter data for evaluating the so-called (stationary) Sea Surface Topography (SST). In turn, SST can
be used for estimating the ocean circulation that is connected to many physical phenomena (e.g. climate changes).
This approach has been widely applied at a global scale for which reliable and detailed geostrophic currents have
been estimated. The same procedure is proposed, at a regional scale, in the Mediterranean area. A detailed geoid
estimate will be computed based on gravity data collected in the area using either Stokes/FFT and collocation
approaches. The remove-restore procedure will be applied using the more recent global geopotential models
(EGM2008, EIGEN-6c3 and satellite only derived models) and a detailed DTM/bathymetry (SRTM and NOAA
data will be used). In this way, a remarkable improvement in the geoid estimate is expected with respect to previous
computations (e.g. the GEOMED project estimate). Comparisons with existing GPS, LRM, SAR and SAR-in
altimeter data will then allow estimating a refined SST, both over open-ocean and coastal areas, which will be used
to compute permanent and seasonal currents in the Mediterranean Sea. In this paper, the methodology adopted by
the team is illustrated: the preparation of the databases is presented together with some preliminary geoid
computations.
ANALUIS OF EARTHQUAKES PATTERNS IN IRAN BASED ON THE
DEFELECTION OF VERTICAL COMPONENTS OF THE EGM2008 GLOBAL
GEOID MODEL
R. Kiamehr
Department of Geography, Zanjan University, 45195-313, Zanjan, Iran, Email: [email protected]
Abstract: Only with satellites it is possible to cover the entire Earth densely with gravity field related measurements
of uniform quality within a short period of time. A new Earth Gravitational Model (EGM2008) to degree 2160 has
been developed incorporates improved 5 5 minute gravity anomalies and has benefited from the latest GRACE
based satellite solutions. Due to the high altitude of the satellite, the effects of the topography and the internal
masses of the Earth are strongly damped. However, the deflection of vertical components, are the second order
spatial derivatives of the gravity potential, efficiently counteract signal attenuation at the low and medium
frequencies. In this article we review the procedure for estimating the deflection of vertical components based on
the spherical harmonic coefficients of the EGM2008 global combined geoid model. Then we apply this method as a
case study for the interpretation of possible earthquakes patterns in Iran. We found strong correlations between the
components of the deflection of vertical, and earthquakes patterns in Iran. It can be used for detecting of possible
hidden faults in the study areas for establishment of the deformation monitoring networks based on the GPS.
Key Words: Deflection of the Vertical Components, EGM2008, Earthquakes, Iran
60
Treatment of ocean tide aliasing in the context of a next generation gravity field
mission
R. Pail*, M. Murböck, J. Honecker, H. Dobslaw
* Tech. Univ. Munich, Germany
[email protected]
Abstract: One of the most promising configurations of a future gravity field mission beyond GRACE-FO will be a
double-pair formation of two in-line pairs in a so-called Benderconfiguration. In spite of the fact that it has been
shown in several previous studies that temporal aliasing can be significantly reduced by this constellation, also in
this case ocean tide aliasing will still be one of the main limiting factors for the gravity field performance. In
addition to the optimum orbit choice, which can further significantly reduce temporal aliasing or at least shift
the effect to certain bands in the harmonic spectrum (Murböck et al. 2013, J Geod), improved processing strategies
and extended parameter models should be able to further reduce the problem.
In this contribution, several methods dealing with the reduction of ocean tide aliasing are investigated both from a
methodological and a numerical point of view. One of the promising strategies is the co-estimation of selected tidal
constituents over long time periods. The dependencies on orbit configurations and resulting aliasing periods are
investigated in detail. These improved estimates for ocean tide signals can then be used in a second step as an
enhanced de-aliasing product for the computation of short-period temporal gravity fields. From a number of
theoretical considerations and numerical case-studies, recommendations for an optimum orbit selection with respect
to reduction of ocean tide aliasing shall be derived.
An interesting approach to improve especially non-tidal temporal aliasing is the co-estimation of short-period
low-degree gravity fields (“Wiese approach”). As a further aspect of this work, the cross-correlation of the Wiese
approach with the co-estimation of tidal parameters is analysed in detail.
Airborne gravimetry for geoid and GOCE
Rene Forsberg, Arne Vestergaard Olesen, Jens Emil Nielsen
National Space Institute, Technical University of Denmark
Juliane Maries Vej 30, DK2100 Copenhagen, Denmark
Abstract: DTU-Space has since many years carried out large area airborne surveys over both polar, tropical and
temperate regions, especially for geoid determination and global geopotential models. Recently we have started
flying two gravimeters (LCR and Chekan-AM) side by side for increased reliability and redundancy. Typical
gravity results are at the 2 mGal rms level, translating into 5-10 cm accuracy in geoid. However, in rough
mountainous areas results can be noisier, mainly due to long-period mountain waves and turbulence.
In the paper we outline results of surveys and recent geoid determinations in Antarctica, Chile and Tanzania based
on DTU-Space aerogravity and GOCE, as well as the impact of multi-mission airborne gravity (NASA IceBridge
and older surveys) for determining the new Greenland geoid. In all cases the airborne data validate GOCE to very
high degrees, and confirms the synergy of airborne gravity and GOCE.
For Antarctica, the latest DTU-Space Antarctic campaign 2013, carried out in cooperation with the British Antarctic
Survey, Norwegian Polar Institute, and the Argentine Antarctic Institute, involved air drops of fuel to a remote field
61
camp in one of the least explored region of deep interior Antarctica, showing that it is possible efficiently to cover
even the most remote regions on the planet with good aerogravity. With the recent termination of the GOCE
mission, it is therefore timely to initiate a coordinated, preferably international, airborne gravity effort to cover the
polar gap south of 83 S, to obtain a truly global coverage of the earths gravity field at the GOCE resolution; such a
survey can in principle logistically be done in a single season.
New geoid of Greenland – a case study of terrain and ice effects, GOCE and local
sea level data
Rene Forsberg, Tim Jensen
National Space Institute, Technical University of Denmark
Elektrovej 327, DK2800 Lyngby, Denmark
[email protected]
Abstract: Making an accurate geoid model of Greenland has always been a challenge due to the ice sheet and
glaciers, and the rough topography and deep fjords in the ice free parts. Terrestrial gravity coverage has for the
same reasons been relatively sparse, with an older airborne survey of the interior being the only gravity field data
over the interior, and terrain and ice thickness models being insufficient both in terms of resolution and accuracy.
This data situation has in the later years changes sufficiently, first of all due to GOCE, but also new airborne gravity
and ice thickness data from the NASA IceBridge mission, and new terrain models from ASTER, SPOT-5 and
digital photogrammetry.
In the paper we use all available data to make a new geoid of Greenland and surrounding ocean regions, using
remove-restore techniques for ice and topography, spherical FFT techniques and downward continuation by least
squares collocation. The impact of GOCE and the new terrestrial data yielded a much improved geoid. Due to the
lack of of levelling data connecting scattered towns, the new geoid is validated by local sea level and dynamic
ocean topography data, and especially collected GPS-tide gauge profile data along fjords. The comparisons show
significant improvements over EGM08 and older geoid models, and also highlight the problems of global sea level
models, especially in sea ice covered regions, and the definition of a new consistent vertical datum of Greenland.
Precise modelling of the static gravity field from GOCE data using the method of
fundamental solutions
Róbert Čunderlík
Dept. of Mathematics, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Slovakia
[email protected]
Abstract: The method of fundamental solutions (MFS) is used to derive the disturbing potential and gravity
disturbances from the second derivatives observed by the GOCE satellite mission. Namely, the radial components
Tzz of the gravity disturbing tensor are processed to evaluate the unknown coefficients in the source points that are
located directly on the real Earth’s surface. MFS as a mesh-free boundary collocation technique uses the
fundamental solution of the Laplace equation as its basis functions. Hence, the system matrix is created by the
second radial derivatives of the fundamental solution that depend solely on geometrical parameters, i.e. on direct
62
distances between the GOCE observations and the source points. Once the coefficients are evaluated, the disturbing
potential and gravity disturbance can be computed in any point above the Earth’s surface. To obtain their values
directly on the Earth’s surface, e.g. at the source points, the singular boundary method (SBM) can be applied. The
key idea of SBM is to isolate singularities of the fundamental solution and its derivatives using some appropriate
regularization techniques.
This study presents results of processing 20 datasets of GOCE measurements, each for different 61-days period. To
obtain “cm-level” precision, the source points are regularly distributed over the Earth’s surface with the
high-resolution of 0.075 deg (5,760,002 points). For every dataset the radial components Tzz as input data are
filtered using the nonlinear diffusion filtering. The large-scale parallel computations are performed on the cluster
with 1TB of the distributed memory. A combination of numerical solutions obtained for different datasets/periods
yields the final static gravity field model. Its comparison with the SH-based satellite-only geopotential models like
GOCO03S or GOCE-DIR4 indicates its high accuracy. Standard deviation of differences evaluated at altitude 235
km above the reference ellipsoid is about 0.05 m2s-2 ( 5 mm) and 0.01mGal, and on the Earth’s surface about 1.7
m2s-2 ( 17 cm) and 7.2 mGal. Finally, the geopotential on the DTU10 mean sea surface is computed resulting in
the W0 estimates.
Spectral and spatial characteristics of the refined CRUST1.0 gravity field
Robert Tenzer 1, Wenjin Chen 1, Dimitrios Tsoulis 2, Mohammad Bagherbandi 3,4,
Lars E Sjöberg3, Pavel Novák 5, Shuanggen Jin 6
1
Wuhan University, 129 Luoyu Road, Wuhan, China
2
Department of Geodesy and Surveying, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
3
4
Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden
Department of Industrial Development, IT and Land Management University of Gävle, Gävle, Sweden
5
New Technologies for the Information Society (NTIS), Faculty of Applied Sciences,
University of West Bohemia, Plzeň, Czech Republic
6
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, China
Abstract: We investigate the density structure of the oceanic and continental crust using the global crustal model
CRUST1.0, which has been refined by incorporating additional global datasets of the topography/bathymetry
(ETOPO1), the polar ice sheets (DTM2006.0 ice-thickness data) and the global geoid model (GOCO-03S). The
analysis reveals that the average crustal density is 2830 kg/m3, while it decreases to 2490 kg/m3 when including
the seawater. The average density of the oceanic crust (without the seawater) is 2860 kg/m3, and the average
continental crustal density (including the continental shelves) is 2790 kg/m3. We further compile the gravity field
quantities generated by the Earth’s crustal structures. The correlation analysis of results shows that the gravity field
corrected for major known anomalous crustal density structures has a maximum (absolute) correlation with the
Moho geometry. The Moho signature in these gravity data is seen mainly at the long-to-medium wavelengths. At
higher frequencies, the Moho signature is weakening due to a noise in gravity data, which is mainly attributed to
crustal model uncertainties. The Moho determination thus requires a combination of gravity and seismic data. In
global studies, gravimetric methods can help improving seismic results, because (i) large parts of the world are not
yet sufficiently covered by seismic surveys, and (i) global gravity models have a relatively high accuracy and
resolution. In regional and local studies, the gravimetric Moho determination requires either a detailed crustal
63
density model, or seismic data (for a combined gravity and seismic data inversion). We also demonstrate that the
Earth’s long-wavelength gravity spectrum comprises not only the gravitational signal of deep mantle
heterogeneities (including the core-mantle boundary zone), but also shallow crustal structures. Consequently, the
application of spectral filtering in the gravimetric Moho determination will remove not only the gravitational signal
of (unknown) mantle heterogeneities, but also the Moho signature at the long-wavelength gravity spectrum.
Keywords: correlation, crust, density, gravity, mantle, Moho
Global gravimetric crustal thickness based on uniform and variable models of the
crust-mantle density interface
1
Robert Tenzer, 1Wenjin Chen and 2Shuanggen Jin
1
Wuhan University, 129 Luoyu Road, Wuhan, 430079 China
2
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
Abstract: A constant value of the Moho density contrast is often assumed in gravimetric methods, which are used
for a determination of the Moho geometry. This assumption might be sufficient in regional studies with a relatively
homogenous lithospheric structure (and consequently small lateral variations in the Moho density contrast). In
global studies, however, this assumption is not reasonable due to the fact that not only the Moho depth, but also the
Moho density contrast vary significantly. This assumption thus likely yields a systematic bias in the Moho
geometry determined globally from gravity data. In this study we address this issue by investigating the effect of
the variable Moho density contrast on the Moho geometry. We demonstrate that the assumption of the variable
Moho density contrast (instead of a uniform model) significantly improves the agreement between the global
gravimetric and seismic Moho models; the RMS fit of the gravimetric result with the CRUST1.0 seismic Moho
model is 4.5 km (for a uniform model) and 3.0 km (for a variable model).
Keywords: crust, density contrast, gravity, upper mantle, Moho interface
The International Gravimetric Bureau (BGI) : tasks and objectives
S. Bonvalot 1, F. Reinquin1, G. Balmino1, R. Biancale1, A. Briais1, S. Bruinsma1, G. Gabalda1, L. Seoane1 ,
H. Wilmes2, H. Wziontek2
1
Bureau Gravimétrique International (BGI)/IRD, Toulouse, France
2
Federal Agency for Cartography and Geodesy (BKG), Frankfurt, Germany
Abstract: The Bureau Gravimetrique International (BGI) is one of the IAG services coordinated by the
International Gravity Field Service (IGFS). Its major task is to ensure the data inventory and the long term
availability of the surface gravity measurements acquired on Earth (Geodesist’s Handbook, 2012, International
Association of Geodesy, Springer Verlag., Vol. 86, 10, Oct. 2012). For more than 60 years, BGI plays a significant
role in the worldwide compilation and validation of gravity data and their distribution to the international
community and stimulates the use of gravity observations for a wide number of scientific / educational applications
(geodesy, oceanography, geophysics…). The data and products available from the BGI website
(http://bgi.obs-mip.fr) include:
A global relative gravity database which contains over 12 million of observations compiled from land, marine and
64
airborne gravity measurements, which are frequently, used in the definition or validation of global or regional geoid
and gravity models.
A global absolute gravity database (AGrav) designed and implemented in a joint development of BKG
(http://agrav.bkg.bund.de) and BGI (http://agrav.obs-mip.fr). According to the growing number of absolute
gravimeters and absolute gravity measurements all over the world, the need of an international database has been
emphasized to provide an overview about existing locations, observations, instruments and institutions involved.
Prospectively, the database will be the foundation for a future international gravity reference system (replacing the
obsolete IGSN71).
High resolution global models of gravity anomalies computed in spherical geometry such as for instance the
WGM2012 Bouguer and Isotatic model. The latter includes terrain corrections (resolution 1’x1’) and takes into
account the contribution of most surface masses (atmosphere, land, oceans, inland seas, lakes, ice caps and ice
shelves). It is also based on new theoretical developments performed to achieve accurate computations at global
scale using spherical harmonic approach.
The current BGI activities and their contribution to IGFS/GGOS will be highlighted.
Field measurements of Absolute Gravity: current status, examples and
perspectives
S. Bonvalot 1, G. Gabalda1 , T. Gattacceca2 , N. Le Moigne3
1
Bureau Gravimétrique International (BGI)/IRD, Toulouse, France
2
Institut Géographique National (IGN), St Mandé, France
3
Geosciences Montpellier, CNRS, Montpellier, France
Abstract: The development in the last decade of the Micro-g A10 portable gravity meter has significantly enhanced
our capability to perform precise Absolute Gravity measurements in field conditions. Even if previous laboratory
instruments, also based on free-fall technique (FG5 for instance), have been also used in outdoor conditions for
many years, the development of rugged field portable instruments is likely to increase the amount of gravity
observations at a few microGal level. A large variety of scientific or metrological applications requiring precise
measurements of the static or variable gravity field is concerned: geodesy, geodynamics (tectonics, earthquake or
volcano studies), hydrology, calibration lines, reference stations, etc. The A10 gravity meter has provided a first
step in this quest of field measurements of absolute gravity. We present here the results currently obtained from our
own experience with the A10 gravity meter in various field conditions for the establishment of gravity networks
and for geodynamic studies. We also discuss these results with the expected perspective of future new gravity
instrumentations such as provided by cold atom gravity meters.
An airborne gravimetry comparison of stable platform gravimeter LCR and
strapdown airborne gravimeter SGA-WZ
Shaokun Cai, Meiping Wu, Kaidong Zhang, Juliang Cao, Yapeng Yang, Ruihang Yu, Hongwei Wei
Department of Automatic Control, College of Mechatronics and Automation, National University of Defense Technology, Changsha,
410072, China
E-mail:
65
Shaokun Cai : [email protected]; Meiping Wu: [email protected];
Kaidong Zhang: [email protected]; Juliang Cao: [email protected]
YapengYang: [email protected]; Ruihang Yu: [email protected]
Hongwei Wei: [email protected]
Abstract: China has developed a strapdown gravimeter based on SINS/GPS named SGA-WZ. Some airborne
gravity results have been obtained using this system, showing comparable accuracies comparing with the damped
two-axis stable platform gravimeter system (LCR gravimeter). LCR gravimeter has been identified as an effective
instrument to obtain gravity field information. In April 2012 some flight tests were implemented to test the
strapdown gravimetry system SGA-WZ and LCR gravimeter side by side. This was the first time such a
comparison flight with these two systems was undertaken. The fights were undertaken in Hainan province. The test
contains one repeated flight and two grid flights. The flying altitude was about 1500m. The average flying speed
was about 120m/s. The results and analysis of this test are presented. The evaluation of the repeatability is based on
repeated flights and the evaluation of the internal accuracy is based on grid flights. The results of the test show that
the estimated gravity from the two systems agrees at 2 mGal, and the repeatability of SGA-WZ is better. It appears
that the strapdown system SGA-WZ can provide ideal airborne gravity survey information.
Estimating the time evolution of the geoid
Siavash Ghelichkhan
Institut für Astronomische und Physikalische Geodäsie (IAPG), Technische Universität München, Germany, Arcisstraße 21, 80333
München, [email protected]
Abstract: Since temperature fl uctuations can also be identifi ed with density anomalies, which influence the
Earth’s external gravitational fi eld, gravity provides a good constraint for geodynamic modelling. We find a very
high correlation of our model geoid for the present time to current satellite derived geoid solutions. Furthermore,
we are able to determine a whole geoid time-series for the past 40 Ma, where remarkable geodynamic features can
be recognized, especially the sinking of the Farallon and the Tethys slab through the Earth’s mantle. With the help
of the adjoint method, we are able to determine an optimal initial condition iteratively, given a temperature model
of the present time. The seismic velocities are converted into temperature using a published self-consistent
mineralogical model. Finally, we end up with a time series of the temperature distribution in the Earth’s mantle for
a period of time which leads to the dynamic topography included gravitational potential/geoid of the given density
structure.
Genetic-algorithm based search strategy for optimal scenarios of future dual-pair
gravity satellite missions
Siavash Iran-Pour*, Tilo Reubelt, Matthias Weigelt, Michael Murböck, IliasDaras, Stefania Tonetti, Stefania Cornara, Thomas Gruber,
Tonie van Dam,Roland Pail, Nico Sneeuw
*University Stuttgart, Germany
[email protected]
66
Abstract: Recently, research into time-variable gravity field recovery from satellite missions has focused on the use
of double satellite pairs in order to achievehigher temporal and spatial resolutions. However, the search space for
finding optimal scenarios of double pair is vast. The performance of mission scenarios is a function of orbital
parameters of both pairs. The inclinations of each pair, the evolution of ground-track pattern distribution of the
missions within time, missions’ altitudes, relative ascending node angles of the pairs and inter-satellite distances
within each pair have important impacts on the gravity recovery quality of the mission scenarios. This work
employs genetic algorithms on top of expertise from previous studies to find nearoptimal scenarios. In fact, the
genetic algorithm approach is used as the main search strategy tool of this research, where restrictions from our
previous experiences are considered in the running process as well. Moreover, experience-based knowledge is also
employed for tuning the results from the genetic algorithm. The procedure also utilizes time-series analysis to study
the behavior of the geophysical signals in long time period. The geophysical signals and error models for
atmosphere, ocean, hydrology, ice, solid Earth and ocean tides are taken from former studies, as well as from our
consideration.
ANALYSIS OF DISTORTIONS AND OFFSETS IN BRAZILIAN VERTICAL
NETWORK
SÍLVIO R. C. DE FREITAS1, VAGNER G. FERREIRA2,HENRY D. MONTECINO3
MARLY T. Q. S. DA SILVA1, RUTH M. MOREIRA1, ROBERTO T. LUZ1
1
Federal University of Paraná, Earth Science Sector, Department of Geomatics, Curitiba, Brazil,
[email protected]; [email protected]; [email protected];
2
3
Hohai University, School of Earth Sciences and Engineering, Nanjing, China, [email protected];
Concepcion University, Department of Geodetic Science and Geomatics, Los Angeles, Chile, [email protected];
4
SIRGAS - WGIII, Rio de Janeiro, Brazil; [email protected]
Abstract: There are several studies under development for understanding how to face the connection of vertical
networks of South American countries in the context of Geocentric Reference System for the Americas project,
Working Group III - Vertical Datum (SIRGAS – WGIII). Most of height systems in South America are based on
leveled heights and some on normal-orthometric height systems, each one realized along different time spans and in
general without external control of deformations. Beside this, the Amazonian rainforest area involving about a
quarter of South American continent is practically inaccessible for conventional spirit leveling. This region, with
large part in Brazil and few parts in other South American countries, is nowadays place of several engineering
projects, mainly related to mineral and energy exploration with strong implications for environment. Most of
benchmarks in Brazilian Fundamental Vertical Network (BFVN) are linked to the Imbituba Brazilian Vertical
Datum (BVD-I), Southern Brazil, and a small segment is referred to the Santana Brazilian Vertical Datum (BVD-S),
Northern Brazil, which is placed in the northern part of Amazon Estuary. Both BVDs were realized from mean sea
level determination, each one at different epoch and time span. The heights of the BFVN were realized by spirit
leveling reduced to a normal-orthometric system, without additional control, even considering benchmarks located
more than 4,000 km from the southern datum. Nowadays, there is no possibility for connecting the two segments of
BFVN with base in conventional leveling techniques. It must be mentioned that several mega engineering projects
in the Amazonian region and in border areas are only based on local vertical systems without link with BFVN. We
considered in the present study the problems associated to the connection and deformation analysis on the two
independent parts of the BFVN with basis in the concept of a World Height System (WHS). We also considered the
67
problems associated to the connection of several local height systems in Brazil which must be connected to the
BFVN because of juridical aspects of environmental control. In the present work, the main approach is based on the
association of co-located Global Positioning System (GPS) in selected benchmarks with satellite-only and
combined Global Geopotential Models (GGMs). Other techniques for obtaining geopotential numbers in a WHS
were explored. The approaches were developed in order to model the deformations and to connect the two portions
of the BFVN. Additionally, the possibilities for applying the approach for linking local height systems to the BFVN
are also discussed.
Looking for sedimentary basins using global gravity field and crustal models
Stefano Colpani and Gabriel Strykowski
the Technical University of Denmark, DTU
Space, National Space Institute, at Elektrovej 327, DK-2800, Kgs. Lyngby, Denmark.
E-mail(s): [email protected] and [email protected]
corresponding author: Stefano Colpani, MSc graduate DTU
Homepage: http://center.shao.ac.cn/geodesy/colpani.html
Abstract: Publicly available and newly released global crustal model CRUST1.0 (Laske et al., 2013), in
combination with the satellite-only based global gravity model GOCO03s (Mayer-Gürr et al., 2012), yield a
possibility of combining global source models with global gravity field models.
The height and depth to the top and to the base of a set of geological units obtained from the global crustal model
are used to fix the source geometry. This information is subsequently used to forward precompute the global gravity
signature of these units in different heights above the sources and for unit mass density. The average
seismic-impedance-derived global mass density for the geological unit acts like a scaling factor and thus the
relation to the gravity signal becomes linear. Computations are done both for Tz (defined as a gravity disturbance)
and for the whole gravity gradient tensor, e.g. Tzz, Tzx, and Tzy components, where x y and z refer to a local
East-North-Up (-NED) Cartesian reference frame.
The above set-up allows constructing a model of the regional (gravity) field both for Tz and for selected gravity
gradient components Tzz, Tzx, and Tzy, thought improving it on a regional scale. In principle, the method allows to
keep track of the relation between the regional signal and the source model. Subsequently, a generalized linear
inverse Nettleton’s method can be used to fine-tune apparent bulk mass densities for sedimentary layers from any
above type of gravity data and a combination of it.
Finally, for the well-surveyed areas, the results can be compared with the independent information about the basin
geometry, e.g. as given by the Robertson Tellus BEAR database of CGG Veritas & Fugro Geoscience. This
experience shall be used further to prospect the shape of sedimentary basins in areas where their knowledge is
limited.
GOCE Gravity Field Models – Overview and Performance Analysis
Th. Gruber, R. Rummel, HPF Team
Institut für Astronomische und Physikalische Geodäsie (IAPG), Technische Universität München, Germany
Abstract: In October 2013 the GOCE successfully completed its mission and delivered a unique data set of
68
gradients of the Earth gravity field. During the final mission phase the satellite orbit was lowered in several steps
by all together 30 km with respect to the operational orbit. By being closer to the attracting masses the sensitivity of
the satellite to the Earth gravity field could be increased significantly. ESA’s high level processing facility delivered
in spring 2013 the 4th release of the GOCE based gravity field models. The next version (rel. 5) which soon will be
released to the user community will be based on the complete mission data set. Preliminary analyses show that the
performance of the final release can be significantly improved with respect to all previous models. The paper
provides an overview about the characteristics of the available GOCE models and estimates of their performance
based on a number of validation results.
Scientific Roadmap towards Height System Unification with GOCE
Th. Gruber, R. Rummel1, M. Sideris, E. Rangelova2, P. Woodworth, C. Hughes3
J. Ihde, G. Liebsch, U. Schäfer, A. Rülke4, Ch. Gerlach5,R. Haagmans6
1
Institut für Astronomische und Physikalische Geodäsie (IAPG), Technische Universität München, Germany,
2
Department of Geomatics Engineering, University of Calgary, Canada
3
National Oceanography Centre Liverpool, United Kingdom
4
Bundesamt für Kartographie und Geodäsie (BKG), Frankfurt/Main, Germany
5
Kommission für Erdmessung und Glaziologie, Bayerische Akademie der Wissenschaften, Germany
6
European Space Agency, Netherlands
Abstract: GOCE allows the determination of geoid heights with an accuracy of 1-2cm and spatial resolution of
about 100 km. An important application that will benefit from this is the global unification of the (over 100)
existing height systems. GOCE will provide three important components of height unification: highly accurate
potential differences (geopotential numbers), a global geoid- or quasi-geoid-based reference surface for elevations
that will be independent of inaccuracies and inconsistencies of local and regional data, and a consistent way to refer
to the same datum all the relevant gravimetric, topographic and oceanographic data. The paper summarizes results
of a project supported by the European Space Agency and specifies a scientific roadmap on how GOCE can support
world height system unification.
Analysis of Aircraft Dynamics from Seven Years of AerogravityData Collection
Theresa M. Damiani, Vicki A. Childers, and Sandra A. Preaux
National Geodetic Survey, National Oceanic and Atmospheric Administration, 1315 East-West Highway, SSMC-3, Silver Spring, MD
20910
Abstract: The Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Program has been collecting
airborne gravity data over the United States since 2007, to support the adoption of a gravimetric geoid-based
vertical datum in 2022. After seven years, the program has completed data collection for over 30% of the United
States and its holdings. Over that time period, GRAV-D has used eightdifferent aircraft, which were flown at
several altitudes between 12,500 and 35,000 feet (Table 1). These aircraft were alsoflown in different seasons and
in different parts of the country with differences noticeable to field crew in the behavior and stability of the various
aircraft. The goal of this analysis is to compare flight dynamics of the different aircraft and the same aircraft in
different conditions to inform the future uses of these platforms. On all surveys, an inertial navigation system
69
recorded aircraft dynamics and at least two geodetic-grade GPS receivers recorded aircraft position. For every
flight done, the data will be broken up into data lines collected and turns executed between lines. First, we compile
basic statistics on the variability (RMS and standard deviation), mean, and maximum range of the following
metrics of aircraft motion: pitch, roll, and crab angle (difference between direction of flight from GPS and the true
heading of the aircraft from inertial measurements), aircraft velocity, and accelerations. Analysis of the pitch, roll,
and crab angle will reveal any dominant modes of motion - such as phugoid and dutch roll. Those dynamics will be
compared to environmental variables (e.g. wind speed and direction), aircraft-dependent variables (e.g. weight,
high or low mounted wings, number of engines) and quality of the final airborne gravity solutions for these
surveys.
Table 1: Aircraft Platforms Used by GRAV-D since 2007
Aircraft
Aircraft
Operator
Cessna
NOAA
II
Airborne
Services, Inc.
Nominal
Aircraft
Altitude (ft)
35,000
Turboprop
Double
4
20,000
Turboprop
Double
1
12,500
3
20,000
Pilatus (PC-12)
Turboprop
Single
9
20,000
Lockheed P-3 Orion
Turboprop
Four Engine
1
20,000
Turboprop
Double
2
20,000
Cessna 441 Conquest II Turboprop
Double
3
17,500
Double
1
20,000
Beechcraft
King Air (RC-12)
NOAA
Completed with
6
Research Hawker
Management
Survey
Double
(695A)
Bureau of Land
Engine
Number of Surveys
Jet
TurboCommander 1000
Lab
Fugro
Citation
(CE-550)
NOAA
Naval
Jet/Turboprop
Single/Double
Hawker
Beechcraft
King Air E90A
Dynamic
Hawker
Aviation, Inc.
King Air E90A
Beechcraft
Turboprop
A First Traceable Gravimetric Calibration Line in the Swiss Alps
Urs Marti1, Henri Baumann2, Beat Bürki3, Christian Gerlach4
1
Federal Office of Topography swisstopo, Wabern, Switzerland;
2
3
4
Federal Institute of Metrology, Wabern, Switzerland;
Geodesy and Geodynamics Lab, ETH Zurich, Switzerland
Bayerische Akademie der Wissenschaften, Munich, Germany
Abstract: In order to determine scale factors of relative gravimeters it is necessary to calibrate these instruments
regularly on points with known gravity values. Especially well suited are points with absolute measurements and
with large gravity differences. This implies that gravimetric calibration lines are usually implemented in
North-South direction or on stations with big height differences. The latter has the advantage that traveling time can
be kept rather short. In 2013 we established a calibration line in the Swiss Alps between Interlaken (altitude 570 m)
and Jungfraujoch (altitude 3500 m). This line consists of 7 absolute stations measured with an FG5X and several
eccentric points. The total gravity difference is more than 600 mgal. All absolute stations are easily accessible by
70
car or are located in the immediate vicinity of a station of the Jungfrau railway. Therefore, it is possible to measure
the whole line with relative instruments in a closed loop in one day. The absolute stations have been chosen in a
way that they are accessible during the whole year and that the gravity difference between two neighboring stations
does not exceed 150 mgal. So, it is possible to calibrate as well gravimeters with a limited measuring range (e.g.
Lacoste&Romberg Type D meters). The expanded uncertainties of the absolute stations are varying between 5 and
6 μGal. Relative between the stations, the expanded uncertainty is reduced to around 3 μGal. All vertical gradients
have been determined by relative measurements on three levels. The newly established calibration line is free to be
used by the whole gravity community and we hope that many institutions will profit. It is to our knowledge
worldwide the first traceable calibration line satisfying the BIPM Mutual Recognition Arrangement (MRA).
The paper describes the details of the establishment of the calibration line, the absolute measurements and a first
comparison with relative measurements with a Scintrex CG-5 and a ZLS Burris instrument.
Hydrological impact on the discharge of Volta River basin of West Africa due to
the water impoundment by using satellite base data
Vagner G. Ferreitra 1, Ehsan Forootan 2, Joseph L. Awange 3, Samuel A. Andam-Akorful 1
1
Hohai University, School of Earth Sciences and Engineering, Nanjing, China, [email protected]
2
3
Bonn University, Institute of Geodesy and Geoinformation, Bonn, Germany
Curtin University, Western Australian Centre for Geodesy and The Institute for Geoscience Research, Perth,Australia
Abstract: With many remote sensing products available for all kinds of terrestrial water-storage (i.e., surface water
reservoirs, ice, soil moisture and groundwater), it seems to be possible to close the water budget equation over a
desired river basin as shown by several authors. In this particular study case over Volta River basin of West Africa,
we will explore the available satellite data such as terrestrial water-storage changes (GRACE), rainfall (TRMM),
evapotranspiration (MODIS), and atmospheric moisture storage and divergence (ERA-Interim reanalysis data) to
estimate the total fresh water discharge into Gulf of Guinea using the land and coupled land-atmosphere water mass
balance approaches. The initial results appear to indicate that closure of water budget over Volta Basin is not
possible mainly due to the water impoundment of the Lake Volta. However, after taking into account the mass
changes due to the Lake Volta’s level variations from satellite altimetry on the terrestrial water-storage changes, we
show that it is possible to assess the total discharge of the Volta Basin.
SGNoise - a tool for the ambient noise level analysis at superconducting
gravimeter stations
Vojtech Pálinkáš, Miloš Vaľko
Research Institute of Geodesy, Topography and Cartography, Geodetic Observatory Pecný, 25165 Ondřejov 244, Czech Republic
Abstract: The SGNoise represents a web tool for the near real-time analysis of data from superconducting
gravimeters (SGs). Gravity residuals are computed on daily basis from raw SG data (1 sec sampling rate) and
analysed/visualized in time and frequency domain. It fulfills the main goal of the SGNoise - automatic data quality
control of continuously operating geophysical instruments for providing a helpful service for operators and data
users. The data quality quantification is represented by the evaluation of ambient noise level at SG stations by
71
spectral analysis of gravity residuals and its visualization through spectrograms and probability density functions.
Among others, it provides a possibility for comparison of noise levels at SG stations as demonstrated in this study
for Pecný, Wettzell and Strasbourg which are included to the SGNoise service at http://oko.asu.cas.cz/grav/. The
SGNoise program package is written in PHP5 using the GD graphical library. Procedures used for data processing
and analysis are consistent with previous works on noise level analysis at SG stations.
On the estimation of diffraction and verticality corrections in absolute
gravimetry
Vojtech Pálinkáš1, Petr Balling2, Petr Křen2 and Jakub Kostelecký1
1
Research Institute of Geodesy, Topography and Cartography, Geodetic Observatory Pecný, 25165 Ondřejov 244, Czech Republic
2
Czech Metrology Institute, Department of Quantum Metrology of Length, V botanice 4, Praha 5, Czech Republic
Abstract: FG5 absolute gravimeters are the most accurate gravimeters available at present and have significant
influence on the realization of a gravity reference through international comparisons of absolute gravimeters.
Sources of systematic error have to be taken into account when determining accurate values of the acceleration due
to gravity, as needed, for example, for the watt balance project or the International Gravity Reference System.
Presented are estimations of diffraction and verticality corrections for the gravimeter FG5#215.
The diffraction effect, caused by a limited beam width / inherent curvature of the laser wave front used in laser
interferometers, depends strongly on the waist of the laser beam. The beam waist and divergence of the FG5#215
laser had been determined by the careful measurement using a profiler and a camera. We have estimated the beam
waist radius of (1.9 ±0.1) mm* with corresponding diffraction correction of (2.8 ±0.3) Gal according to the
equation published in [1] and validated in [2], which significantly differs from the value of 1.2 Gal typically used
for FG5s.
Therefore we decided to validate our results by the experimental way. Two pairs of
focusing-collimating lenses were used in the laser interferometer to reach different beam waists of 1.9 mm and
3.1 mm with corresponding diffraction corrections of 2.8 Gal and 1.0 Gal, respectively. According to these
values it was expected to detect the theoretical difference of (1.8 ±0.4) Gal by means of precise absolute gravity
measurements. However, the difference of (0.53 ±0.26) Gal was found, showing on a clear disagreement between
theoretical and experimental results for diffraction corrections. To explain this disagreement two explanations are
investigated: 1) the effect of significant non-Gaussian profile of the beam passing the superspring, 2) validity of the
equation used for the estimation of diffraction corrections within the Rayleigh range.
The laser light reflecting from the falling test mass must be aligned precisely with the vertical. Deviations from the
verticality for the FG5#215 are regularly controlled once per four hours by operators of the gravimeter. Probability
distribution of a large number of measured deviations showed on the agreement with two-dimensional normal
distribution with standard deviation of 20 rad in both axes. It leads to the determination of the mean of 0.4 Gal
for the verticality correction.
* ±symbol in this text stands for 1- statistics
[1] Van Westrum D., Niebauer T.M. The diffraction correction for absolute gravimeters. Metrologia, Vol. 40, 2003,
258-263.
[2] Robertsson L. On the diffraction correction in absolute gravimetry. Metrologia, 2007, Vol. 44, 35-39.
72
Adaption of the torus- and Rosborough approach to radial base functions
W. Keller1, R. J. You2
1
Geodetic Institute, University Stuttgart,Geschwister-Scholl-Str.24/D, 70174 Stuttgart, Germany
2
Department of Geomatics, National Cheng Kung University,University Road 1, Tainan, Taiwan
Abstract: The most common approach for the processing of data of gravity field satellite missions is the so-called
time-wise approach. In this approach satellite data are considered as a time series and processed by a standard
least-squares approach. This approach has a very strong flexibility but it is computationally very demanding. To
improve computational efficiency and numerical stability, the so-called torus- and Rosborough approaches have
been developed. So far, these approaches have been applied only for global gravity field determinations, based on
spherical harmonics as basis functions. For regional applications basis function with a local support are superior to
spherical harmonics, because they provide the same approximation quality with much less parameters. So far,
torus- and Rosborough approach have been developed for spherical harmonics only. Therefore, the paper aims at
the development and testing of the torus-and Rosborough approach for regional gravity field improvements, based
on radial basis functions as basis functions. The developed regional Rosborough approach is tested against a
changing gravity field produced by simulated ice- mass changes over Greenland. A recovery of the simulated
mass changes with a relative accuracy of 5 % was possible, with a radial basis function model, containing only 350
parameters.
A new gravimetric geoid model for the area of Sudan using the least squares
collocation and a GOCE-based GGM
Walyeldeen Godah, Jan Krynski
Institute of Geodesy and Cartography Department of Geodesy and Geodynamics
27 Modzelewskiego St., 02-679 Warsaw, Poland
e-mail: [email protected], [email protected]
Abstract: The determination of accurate geoid model remains an important challenge for geodetic research in
Sudan. The presented contribution concerns the determination of a new gravimetric geoid model (SUD-GM2014)
for the area of Sudan using recent released GOCE-based GGMs, available terrestrial mean free-air gravity
anomalies and the high-resolution Shuttle SRTM global digital terrain model. The computations of the
SUD-GM2014 were performed using remove-compute-restore (RCR) procedure and the least squares collocation
method. The residual terrain modelling (RTM) reduction method was applied to estimate the topography effect on
the geoid. The resulting gravimetric geoid model has been evaluated using geoid heights at 19 GNSS/levelling
points distributed over the country. The evaluation results and the expected quality of the SUD-GM2014 geoid
model were discussed considering the quality of GNSS/levelling data in Sudan as well as the evaluation of geoid
model in the area with a very good coverage of high quality terrestrial gravity data as well as GNSS/levelling data
developed using the same computing procedure and the same GGM.
Keywords: geoid, global geopotential model, GNSS/levelling, GOCE, least squares collocation
73
On the contribution of GOCE mission to modelling the gravimetric geoid: A case
study - a sub-region of East Africa and Central Europe
Walyeldeen Godah, Jan Krynski, Malgorzata Szelachowska
Institute of Geodesy and Cartography, Department of Geodesy and Geodynamics,
27 Modzelewskiego St., 02-679 Warsaw, Poland
e-mail: [email protected], [email protected]
[email protected]
Abstract: The dedicated satellite gravity missions have provided homogeneous and uniformly accurate information
on the long/medium wavelength of the Earth’s gravity field. The aim of this study is to investigate the contribution
of the GOCE satellite mission data to the long/medium wavelength component (approximately 100 km half
wavelength spatial resolution) of the Earth gravity field. In particular, it concerns the investigation of the
contribution coming from the GOCE mission observables to modelling the gravimetric geoid in two areas with
highly different terrestrial data availability. For this purpose, the area of Poland with a very good coverage of high
quality terrestrial gravity data as well as GNSS/levelling data, and the area of Sudan with poor terrestrial gravity
data coverage and only a few GNSS/levelling points were chosen as study areas. On the basis of the combination of
recently released GOCE-based GGMs and local terrestrial gravity data, gravimetric geoid models for the area of
Poland as well as for the area of Sudan were developed using least squares collocation method. They were
evaluated using GNSS/levelling data. Regarding the obtained evaluation results, the added values from GOCE
mission to the modelling of the gravimetric geoid for these areas have been discussed.
Keywords: geoid, global geopotential model, GNSS/levelling, GOCE, least squares collocation
Consistent Estimates of the Dynamic Figure Parameters of the Stratified Earth
Wei Chen1,2*, JianCheng Li1, Jim Ray3, WenBin Shen1, ChengLi Huang4
1
Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics,
Wuhan University, Wuhan, China.
2
State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics,
Chinese Academy of Science, Wuhan, China.
3
4
National Oceanic and Atmospheric Administration, Silver Spring, Maryland, USA.
Shanghai Astronomical Observatory, Chinese Academy of Science,Shanghai, China.
*
Corresponding author: [email protected]
Abstract: The Earth’s dynamic figure parameters, including the inertia tensors and dynamic flattenings of the whole
Earth and its internal layers (the fluid outer core and the solid inner core), are fundamental parameters for geodetic,
geophysical and astronomical studies, and are usually derived from the degree-2 potential coefficients. Until recently, the
recommended values for these parameters by IAG were solved based on the JGM-3 gravity model with values of GM
and a adjusted. Recently, some new models (such as EGM2008, EIGEN-6C and EIGEN-6C2) with unprecedented
accuracies have been released. In contrast to the ~1-meter-accuracy geoid of JGM-3, the global geoids determined by
some recent gravity models (EGM2008, EIGEN-6C and EIGEN-6C2) can all reach accuracies of ~0.2 meter or even
better (e.g., Li et al., 2012). In addition, the uncertainty in the gravitational constant G has also been reduced by half (e.g.,
74
Petit and Luzum, 2010). Thus it is quite promising to obtain improved values of the Earth’s inertia tensor and then
dynamic figure parameters of the fluid outer core and solid inner core, using the theory described in Chen and Shen
(2010). While the parameters GM and a serve as scaling constants in the determination of the potential coefficients, the
values of GM and a adopted by most gravity models are not consistent with the IAU and IAG numerical standards
(please refer to the IERS Conventions (2010)). Based on GM and a values recommended by the IERS Conventions
(2010), we rescaled the potential coefficients of EGM2008, EIGEN-6C and EIGEN-6C2 to ensure those values to be
consistent with the IAU and IAG numerical standards. Then we obtained consistent estimates of the dynamic figure
parameters of the stratified Earth. Wherein, the principal inertia moments of the whole Earth are A = (80079.8+/-3.6)E33
kg m2, B = (80081.6+/-3.6)E33 kg m2, and C = (80343.7+/-3.6)E33 kg m2, respectively, which might be the best
estimates currently available.
Inter-annual groundwater storage variations in North China from GRACE and
ground observations
Wei Feng, Min Zhong, Hou-ze Xu
State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 340
Xudong Road, Wuhan, 430077, P. R. China
Email: [email protected], Phone: 18694058011
Abstract: Extensive anthropogenic activities in North China, such as agricultural irrigation and urbanization, are
consuming the unrecoverable groundwater resource in the region. Since its launch in 2002, the Gravity Recovery
and Climate Experiment (GRACE) satellites provide a powerful tool to monitor regional groundwater storage
variations. In this paper, we provide a detailed assessment of spatiotemporal variations of groundwater in North
China estimated from two independent methods, i.e., GRACE satellite measurements and ground-based well
observations. We calculate the groundwater storage changes in the region by combining the time-varying gravity
field data from GRACE with outputs from land-surface models. The spatial pattern of GRACE-based groundwater
depletion indicates significant water mass loss in the piedmont and central plain regions of North China since 2002.
The ground-based monitoring well network also indicates that the groundwater table in the piedmont regions of
Taihang Mountains, the east part of North China Plain, declines faster than other regions of North China. In
addition, inter-annual GWS variations are also detected by GRACE and ground observations. Both GRACE and
ground observations show groundwater storage increase during 2012-2013.
5′×5′ global geoid: GG2014-re
WenBin Shen1,2, Jiancheng Han1
1
Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics, Wuhan University, Wuhan, China,
[email protected] (WenBin Shen) ; [email protected] (Jiancheng Han)
2
Wuhan University, Wuhan 430079, China
Abstract: We provide an updated 5′×5′ global geoid GG2014-re, which is determined based on the shallow layer
method (Shen 2006). We choose an inner surface below the EGM2008 geoid by 15 m, and the layer bounded by the
75
inner surface and the Earth’s geographical surface is referred to as the shallow layer. Then, a 3D shallow layer
model is determined based on the digital topographic model DTM2006.0 combining with the DNSC2008 mean sea
surface and the refined 5′×5′ crust density model, CRUST1.0-5min, which is an improved 5′×5′ density model of
the CRUST1.0 with taking into account the corrections of the areas covering by ice sheets and the land-ocean
crossing regions. Then, using a series of techniques and procedures, we established the 5′×5′ global geoid
GG2014-re. Comparisons show that the GG2014-re fits the globally available GPS/leveling points better than the
EGM2008 geoid. This study is supported by National 973 Project China (grant Nos. 2013CB733301 and
2013CB733305), NSFC (grant Nos. 41174011, 41210006, 41128003, 41021061, 40974015).
Keywords: shallow layer method; CRUST1.0-5min; EGM2008; DTM; global geoid
Spectral harmonic analysis of global crustal structure
Wenjin Chen, Robert Tenzer
Wuhan, China
Abstract: We compile and publish the harmonic coefficients, which describe the Earth’s crustal density structure
with a spectral resolution complete to degree/order 180. These coefficients can be used in gravimetric studies of the
Earth’s lithosphere structure, isostasy, crustal loading, sedimentary basins and related topics. The crustal structure
of the Earth’s Spectral Crustal Model 180 (ESCM180) is separated into 9 individual layers of the topography,
bathymetry, polar ice sheets, sediments (3-layers) and consolidated crust (3-layers). The harmonic coefficients
describe uniformly the geometry and density (or density contrast) distribution within each individual crustal
component. The topographic and bathymetric coefficients are generated from the topographic/bathymetric model
ETOPO1 and the global geoid model GOCO03s. A uniform density model is adopted for the topography. The ocean
density distribution is approximated by the depth-dependent seawater density model. The ETOPO1 topographic and
the DTM2006.0 ice thickness data are used to generate the ice coefficients, while assuming a uniform density of the
glacial ice. The geometry and density distribution within sediments is described by the 3 stratigraphic layers of a
laterally varying density model, and the same structure is used to describe the density distribution within the
consolidated crust down to the Moho interface. The sediment and consolidated crust coefficients are generated from
the global crustal model CRUST1.0. The density contrasts of the ocean, ice, sediments and remaining crustal
structures are taken relative to the reference crustal density.
Keywords: crust, density, gravimetric forward modeling, harmonic analysis, model
Crustal stress in Taiwan
Xiang Gu1, Robert Tenzer1 and Cheinway Hwang2
1
Wuhan, China
2
Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan
Abstract: The latest dataset of the marine, areal and terrestrial gravity data is used to investigate the virtual crustal
deformations and crustal stress in Taiwan. The deformation and stress parameters are compared with GPS-derived
velocity and gradient fields. The results reveal some characteristics which are attributed to the crustal thickness and
composition as well as tectonics dominated in this part of the world by subduction and plate collision.
76
Retracking Jason-1 GM and Cryosat-2 LRM waveforms for modelling the
regionally optimal marine gravity field around Taiwan
Xiaoli Deng1, Cheinway Hwang2 and Yung-Sheng Cheng2
1
School of Engineering, The University of Newcastle, New South Wales, Australia,
2
Department of Civil Engineering, National Chiao Tung University, Taiwan
Email of the corresponding author: [email protected]
Abstract: To improve the accuracy of the marine gravity field it is essential to increase the precision and coverage
of the measurements, which are mainly from satellite altimeter-derived sea surface heights over oceans. For the first
time since 1995 two satellite altimetry missions, Jason-1 geodetic mission (GM) and Cryosat-2 Low Resolution
Mode (LRM), provide global measuring sea surface heights at very high spatial scales of ~8 km from Jason-1GM
and Cryosat-2 LRM (406-day and 369-day repeat orbits, respectively). In addition, sea surface heights extracted
from coastal altimetry waveform retracking techniques have recently shown significant improvement in terms of
the precision and along-track resolution. This study, thus, retracks currently available altimeter waveforms from
Jason-1 GM and Cryosat-2 LRM waveforms. Together with other altimeter data from previous missions, the
derived altimeter sea surface heights are used to model a regionally optimal marine gravity field around Taiwan.
The retracking methods used are the full- and sub-waveform fitting, which are specifically developed based on the
waveform features of Jason-1 GM and Cryosat-2 LRM from this study. Unknown parameters estimated from
waveform retracking are analysed to find their error characteristics. Retracking results provide the optimised data
sources for regional marine gravity field recovery. The methodologies and techniques traditionally used for local
and regional gravity determination are reassessed. The modelled gravity field for the study region is compared to
existing models and the latest external gravity data sets.
Errors of geocenter motion estimates from global GPS observations
Xinggang Zhang1, 2, Shuanggen Jin1
1
2
Tel: +86-21-34775294
Abstract: The geocenter motion can be estimated by global GPS measurements, while it was subject to the
uncertainty and errors due to imperfect distribution of GPS stations and aliasing by higher-degree (n>1) loading
terms. In this paper, errors of geocenter motion estimates from global GPS observations are investigated, including
truncated degrees and GPS networks distributions based on three plate motion models NUVEL-1A, MORVEL56
and ITRF08. Results show that the selected GPS stations have no big effects on geocenter motion estimates based
on different plate motion models, while large fluctuations and uncertainties are found either for annual signals or
semi-annual signals at all components when using different truncated degrees. Correlation of geocenter motion
estimates from selected GPS networks by different strategies with GRACE and SLR are better with truncated
degree 1 and 3, and higher truncated degrees will degrade geocenter estimates. RMSs of residuals also show that
77
the results with the truncated degree 3 are better and NUVEL1A has the bigger RMS. As for annual signal with
truncated degree 3, four GPS strategies can reduce annual amplitudes by about 29.2% in X, 5.6 % in Y, 27.9% in Z
with respect to amplitudes at truncated degree 1.While semi-annual signal is not significant for GPS and SLR.
Keywords: Geocenter motion, Surface loading, GPS, GRACE, SLR
Research on precisely matching methods of the accelerometers applied to rotary
accelerometer gravity gradiometer
Xuyang HOU *, Haibing LI, Hui YANG, Cunzun MA
Beijing University of Technology, Beijing 100124, China
Abstract: The rotary accelerometer gravity gradiometer has high requirement on the uniformity of the matched
accelerometers’ scaling factors, and the high uniformity of scaling factors can be achieved by designing proper
feedback circuit. In the article, we first introduce the method of regulating the scaling factor of a single
accelerometer, and the method of detecting the deviation of scaling factors of matched accelerometers. Then,
proper filter and regulator are designed according to the characteristic of scaling factors deviation, and the whole
feedback circuit to regulate uniformity of scaling factors is completed. The related analysis and verifying
experiments shows that the designed feedback circuit effectively adjusts the scaling factors of matched
accelerometers, and expected uniformity is achieved.
Keywords: gravity gradiometer, accelerometer, scaling factor, uniformity, feedback circuit.
An improved w-teststatistic Outlier detection method for GOCE gravity gradients
pre-processing
Yunlong WU, Hui Li, Kaixuan Kang, Xinlin Zhang, Ziwei Liu
Institute of Seismology, China Earthquake Administration
Abstract: GOCE is the first satellite to measure the second order derivatives of the Earth’s gravitational potential
from space. As its scientific objective is to derive a high accuracy and resolution gravitational field, the outliers
have to be removed from the data. It is important to detect as many outliers as possible in the data pre-processing.
For the w-teststatistic shows its wildly application in GPS and inertial navigation, w-teststatistic method is
introduced to the outlier detection algorithms for GOCE data pre-processing. As the diagonal gradients are the main
observables for GOCE data, the tracelessness condition is taken as a priori condition, and then the w-teststatistic
method is applied to estimate the outliers on the GOCE gravity gradient observations with the error model
estimated. Lastly, the interpolation of gravity gradient anomalies are computed, with the outliers flagged and
replaced. The improved outlier detection algorithm, which is a combination of tracelessness condition and
w-teststatistic method, is able to detect almost all types of outliers while the number of undetected outliers remains
small.
Progress of Space Electrostatic Accelerometer in HUST
Z.B. Zhou, Y.Z. Bai, M. Hu, G. Li, L. Liu, J. Luo, S.B. Qu, D.Y. Tan, W.C. Wu
78
Center for Gravitational Experiments, School of Physics, Institute of Geophysics,
Huazhong University of Science and Technology,
1037 Luoyu Road, Hongshan Block, Wuhan, 430074, China
E-mail address: [email protected]
Abstract: Electrostatic inertial sensor has been employed for several space-based experiments to study spatial
environments, map gravitational field of the Earth, and space gravitational experiments. Space electrostatic
accelerometer or inertial sensor has been developed in our group since 2000 in order to push the space gravitational
experiments missions and the satellite gravity measurement. In this talk, we will give a report about the progress of
the electrostatic accelerometer in our group, and measurement by three methods including high-voltage levitation,
fiber suspension, and flight in space. A about 70g test mass is levitated by a high-voltage with output of about 900
V and frequency band larger than 11 kHz, and then six degree-of-freedom control strategy of the test mass are
tested, and a sensitivity about 10-8 m/s2/Hz1/2 below 1 Hz, which is limited by the seismic noise in site. In order to
directly verify the resolution and other performance of the inertial sensor, electrostatic controlled torsion
pendulums, including one stage pendulum and two-stage pendulum, are developed. In this method, seismic noise
effect is suppressed more than 80dB in low-frequency due to common-mode rejection, therefore, the electrostatic
accelerometer or inertial sensor can be investigated at the level of 10-10m/s2/Hz1/2 and ever higher. Finally, an
engineering accelerometer has been tested in flight in the end of 2013, and preliminary result in orbit is presented.
Time-variable gravity signal in Greenland revealed by SWARM high-low
Satellite-to-Satellite Tracking
Zheng-Tao WANG, Neng-Fang CHAO
School of Geodesy and Geomatics, Wuhan University, China
Email: [email protected], [email protected]
Abstract: In the event of a termination of the Gravity Recovery and Climate Experiment (GRACE) mission before
the launch of GRACE Follow-On (due for launch in 2017), So a new satellite plan to continuous monitor the global
time variable gravity field is an urgent need to make sure the series of time variable gravity signal continuity,
Fortunately, SWARM, the three spacecraft will orbit Earth at an altitude of about 300~500 km on near-polar
near-circular trajectories, is comparable to that of the three CHAMPs, as a consequence, it can be continuous
monitor the global time variable gravity field. First, we based on the spherical harmonics which the max degree is
60 of the SWARM, CHAMP and GRACE, analyzed the error characteristics of the series variable gravity field
model coefficient, different Gaussian smoothing radius on the inhibitory effect of high frequency error, and
inversed the global mass change by hl-SST（high-low Satellite-to-Satellite Tracking） and ll-SST（low-low
Satellite-to-Satellite Tracking）, It shows that the high error of SWARM is lower than CHAMP, and the result of
inversed better than CHAMP, but worse than GRACE; Second, we get the ice mass loss over the entire of
Greenland to -268.190±10.8Gt/yr from CHAMP during January 2003 to December 2009, This result is in line with
the findings from GRACE data analysis (-219.952±8.3Gt/yr) over the same period, the trend estimates differ by
only 21.9%; Last but not least, we estimated the ice mass loss trend over the entire of Greenland differ by only
19.2% between SWARM simulation and SWARM ‘True’. We conclude that the hl-SST is fully suitable to assess
Greenland mass balance in the absence of the GRACE satellites, is a viable source of information for time variable
79
gravity and can serve to some extent to bridge a possible gap between the end-of-life of GRACE and the
availability of GRACE Follow-On. Moreover, SWARM results are better than CHAMP.
Key words: SWARM, CHAMP, GRACE, hl-SST, Greenland
Role of Glacial Isostatic Adjustment Process in Present-Day Sea-Level Budget
Closure
Zhenwei Huang1, Hanjiang Wen1, C.K. Shum2
1
Chinese Academy of Surveying and Mapping, Key Laboratory of Geo-information of National Administration of surveying, Mapping
and Geoinformation, 28 Lianhuachixi Road, Beijing, China 100830, [email protected]
2
Division of Geodetic Science, School of Earth Sciences, The Ohio State University, Columbus, Ohio, USA
Abstract: Global sea-level rise has become one of the major social-economic hazards associated with the
consequence of global warming. The major geophysical contribution to present-day sea-level rise is from land ice
reservoirs, which include rapidly ablating mountain glaciers, ice caps, ice-sheets, and potentially from other sources
including abyss ocean steric sea-level rise and imperfect knowledge of the Glacial Isostatic Adjustment (GIA)
process resulting from deglaciation of Pleistocene ice-sheets or from the Little Ice Age. Despite the recent
publications reported on the closure of the ocean mass component of the sea level budget, i.e., the agreement of
steric-corrected altimetry sea-level rise with GRACE estimated ocean mass trend, 2003–2012, we find that the
errors in the current GIA forward model in the seafloor severely limit the budget closure by 0.49 to 1.27 mm yr-1,
indicating the critical importance of the accuracy of seafloor GIA modeling. There is relatively little studies on GIA
modeling over the global seafloor, in part because of the unavailability of observations. Since there is no accurate
seafloor GIA forward model, Seafloor GIA is not separable from the ocean mass variation signals if GRACE is the
only data type used. Here we first quantify the errors in the currently available GIA models over the global seafloor,
with the goal of achieving the sea-level budget closure. Then, we study the feasibility on the use of GRACE,
satellite radar altimetry, Argo and other hydrographic data, towards constraining the current knowledge of the ocean
mass variations of the present-day sea-level budget, while attempting to isolate the seafloor GIA signal.
An approach for determining the geopotential based upon coaxial cable time
transfer technique using atomic clocks
Zi-Yu Shen1,WenBin Shen1,2
1
Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics,
Wuhan University, Wuhan, China, [email protected] (Zi-Yu Shen); [email protected] (WenBin Shen)
2
Wuhan University, Wuhan 430079, China
Abstract: In this study we provide an approach and simulation experiments for determining the geopotential and
orthometric height based upon coaxial cable time transfer technique using atomic clocks. We choose two stations A
and B whose spatial distance is 100 m and height difference is 30 m. Suppose each station is equipped with an
atomic clock with its instability about
3 .2  1 0
16
/

(where
80

is time in second), and these two clocks are a
priori synchronized. The two stations A and B are connected with a coaxial cable for time transfer. Given the true
value of the geopotential difference between A and B, we generated simulated data sets of time comparison. Then,
we estimated the clocks’ running rate difference and the corresponding geopotential difference by least squares
estimate using the simulated data sets. The accuracy in determining the geopotential difference using the proposed
approach was assessed by comparing the true input value and the estimated one. Our simulation experiment results
show that the accuracy is around 0.5 m s (equivalent to 5 cm in height) after a period of observation in four hours.
Due to the fact that the present time transfer technique provides time comparison accuracy better than 10ps via 100
m coaxial cable, and the to-date most precise optical-atomic clocks achieve a stability of 10E-18 level, the proposed
approach in this study is prospective in the near future. This study is supported by National 973 Project China
(grant Nos. 2013CB733301 and 2013CB733305), NSFC (grant Nos. 41174011, 41210006, 41128003, 41021061,
40974015).
Keywords: geopotential; atomic clock; time transfer; coaxial cable
2
2
Test method for determining the anomalous internal structure of terrestrial
planets, space research abased on the example of the Earth
N. A. Chujkova, L. P. Nasonova, and T. G. Maximova
Sternberg Astronomical Institute, Moscow State University, Universitetskii pr. 13, Moscow, 119991 Russia
Till now, we can obtain information about the internal structure of the planets only on the basis of Space Research
of the gravity field and the topography of the planets. It is known that the inverse problem of gravimetry is
incorrect, and its solution is possible only in attracting additional information about the internal structure, and based
on some theoretical conclusions. These conclusions are based on cosmogonic scenarios for the formation of
terrestrial planets, on geophysical and geochemical information and data on high-energy physics. Unfortunately,
such data are currently available only for the Earth, which, based on the interpretation of seismological and seismic
observations and analysis of the splitting of the normal modes of the free oscillations of the Earth have been
identified depth ranges of maximum anomalies of lateral variations of density and seismic wave velocities.
We have developed a method of determining the anomalous internal structure terrestrial planets only on the basis of
Space Research [1, 2]. The essence of this method is the determination of the possible depths of compensation for
expansion harmonics of topographic heights relative to the equilibrium ellipsoid for different-order and
different-degree harmonics. Since each topographic irregularity is characterized by a certain set of the harmonics,
the maximal concentration of compensation of this set within a certain limited depth interval can point to the most
probable depths of compensation of the considered topographic irregularity. If we find the depths of compensation
in such a way, we will be able to solve the formulated problem, i.e. to find the lateral distribution of the anomalous
masses at different depths for the terrestrial planets. We applied our method to study the internal structure of the
Earth, comparing the obtained results with the seismological and free-oscillation data, and to the study of Mars, for
which there are no such observations. Comparative analysis of the results is given in [3].
Reference
1. Chuikova N.A., Nasonova L.P. , and Maksimova T.G. Anomalous structure of the Crust and Mantle of Mars.
ISSN 0027-1349, Moscow University Physics Bulletin, 2011, Vol.66, No. 1, pp. 64-71
81
2. Chuikova N.A., Nasonova L.P. , and Maksimova T.G. Anomalies of Density, Stresses, and the Gravitational Field
in the Interior of Mars. ISSN 0027-1349, Moscow University Physics Bulletin, 2012, Vol.67, No. 2, pp. 218-225
3. Chuikova N.A., Nasonova L.P. , and Maksimova T.G Density, Stress, and Gravity Anomalies in the Interiors of
the Earth and Mars and the Probable Geodynamical Implications: Comparative Analysis. ISSN 1069_3513,
Izvestiya, Physics of the Solid Earth, 2014, Vol. 50, No. 3, pp. 427–443.
Mass anomalies and trends over Russia from GRACE
L. Zotov1, C.K.Shum2, Natalya Frolova1
1
Lomonosov Moscow State University, Russia; 2Ohio State University, USA
GRACE twin-satellites provide monthly data upon the gravitational field of the Earth since 2003, what presents a
big interest for hydrological studies. Gravity data reflect changes, related to the groundwater redistribution, ice
melting, and precipitation accumulation. We use Multichannel Singular Spectrum Analysis to filter GRACE data
and separate the principal components (PCs) of different periods. The obtained animated maps of PCs are useful for
seasonal and long-periodic gravity changes study. Data averaging over the large river basins of Russia was
performed. The obtained curves can be compared to the hydrological models, such as GLDAS or WGHM. By
spring 2013 an extremely large snow accumulation occurred in Russia. Melting of this snow induced large floods
and river levels increase. On the contrary, spring 2014 can be characterized by low snow accumulation. Maps of
mass anomalies, analysis of the trends and comparison with global Climate Change will be presented.
82
4. Participants List
NO.
1
2
3
NAME
AFFILIATION
Abelardo
Polytechnic
Bethencourt
Madrid
Akbar
Shabanloui
Alexander
Horvath
University
COUNTRY
of
EMAIL
Spain
abe.bethe(at)gmail.com
Leibniz Univ. of Hannover
Germany
shabanloui(at)ife.uni-hannover.de
Tech. Univ. Munich
Germany
alexander.horvath(at)tum.de
4
Andres Calabia
SHAO, CAS
China
andres(at)calabia.com
5
Attaullah Khan
SHAO, CAS
China
attaullah.uet(at)gmail.com
SHAO, CAS
China
hassan.ayman(at)shao.ac.cn
6
Ayman
A.
Hassan
7
Balmino Georges
CNES-GRGS
France
georges.balmino(atget.obs-mip.fr
8
Changqing Wang
Ins. Geodesy Geophys., CAS
China
cqwang2013(at)gmail.com
National Chiao Tung Univ.
Taiwan
cheinway(at)mail.nctu.edu.tw
Germany
foer(at)gfz-potsdam.de
9
10
11
12
Cheinway
Hwang
Christoph
GFZ German Res. Centre for
Foerste
Geosci.
Chuandong Zhu
China
zhuchuandong(at)asch.whigg.ac.cn
GReD s.r.l.
Italy
daniele.sampietro(at)polimi.it
Germany
dbecker(at)psg.tu-darmstadt.de
USA
dsalstei(at)aer.com
Brazil
dblitzko(at)usp.br
Daniele
Sampietro
13
David Becker
14
David Salstein
15
16
Technische
Universitaet
Darmstadt
Atmospheric and
Environmental Research
Denizar
Universidade de Sao Paulo
Blitzkow
(USP)
Dongming Zhao
Zhengzhou Surveying and China
83
zhaodongming(at)cntv.cn
Mapping Institute
17
E. Sinem Ince
York Univ.
Canada
seince(at)yorku.ca
18
Erhu Wei
Wuhan University
China
[email protected]
19
Fan Yang
China
mrfanyang90(at)gmail.com
20
Fang Zou
SHAO, CAS
China
fangz070720(at)gmail.com
Franz
GFZ German Res. Centre for
Barthelmes
Geosci.
Germany
bar(at)gfz-potsdam.de
Brazil
gabriel(at)ig.ufu.br
Greece
vergos(at)topo.auth.gr
21
22
Gabriel
Federal Univ. of Uberlandia
Guimaraes
Aristotle
Univ.
of
23
George S. Vergos
24
Gonca Okay Ahi
Hacettepe üniversitesi
Turkey
goncaokayahi(at)hacettepe.edu.tr
25
Guangliang Yang
UCAS
China
3193459(at)qq.com
26
Guiping Feng
SHAO, CAS
China
gpfeng(at)shao.ac.cn
27
Haibing Li
China
lanseshuishou(at)163.com
28
Hanjiang Wen
China
wenhj(at)casm.ac.cn
29
Hao Zhou
Wuhan Univ.
China
lengyeshanren(at)126.com
30
Hongyin Li
HUST, Wuhan
China
hongyin83li(at)googlemail.com
31
Houze Hsu
China
hsuh(at)asch.whigg.ac.cn
Minia Univ.
Egypt
abdelmotaal(at)lycos.com
Tech. Univ. Munich
Germany
daras(at)bv.tu-muenchen.de
Indonesia
ira(at)geodesy.its.ac.id
Finland
Jaakko.Makinen(at)fgi.fi
32
33
34
35
Beijing
Institute
of
Aerospace Control Devices
Hussein
Abd-Elmotaal
Ilias Daras
Ira
Thessaloniki
Chinese
Academy
of
Surveying and Mapping
Mutiara Sepuluh Nopember Inst. of
Anjasmara
Tech.
Jaakko Makine
Finnish Geodetic Institute
84
36
Jack McCubbine
37
Jan Krynski
38
39
40
Jean-michel
Lemoine
New Zealand
jack.c.mccubbine(at)gmail.com
Poland
Jan.Krynski(at)igik.edu.pl
France
[email protected]
Tahiti
jean-pierre.barriot(at)upf.pf
Universidad Del Valle
Colombia
jhon.barona(at)correounivalle.edu.co
Victoria Univ. of Wellington
Ins.
of
Geodesy
Barriot
Tahiti
Mendoza
&
CNES/GRGS, Toulouse
Jean-Pierre
Jhon Jairo Barona
Geodesy
Cartography
Observatory
of
41
Jiandi Feng
Wuhan Univ.
China
jdfeng(at)whu.edu.cn
42
Jianliang Huang
Natural Resources Canada
Canada
Jianliang.Huang(at)nrcan-rncan.gc.ca
43
Junhai Li
SHAO, CAS
China
tjlih(at)vip.qq.com
44
Lajos Volgyesi
Hungary
volgyesi(at)eik.bme.hu
45
Laura Sanchez
DGFI, Munich
Germany
sanchez(at)dgfi.badw.de
46
Lei Zhao
NUDT, Changsha
China
zl_nudt(at)yahoo.com
47
Leonid Zotov
Russia
wolftempus(at)gmail.com
Universidad Del Valle
Colombia
espili87(at)gmail.com
48
Lina
Marcela
Espinal Zapata
Budapest
Univ.
of
Technilogy and Economics
Sternberg
Astronomical
Institute, MSU
49
Liping Zhong
Wuhan Univ.
China
lpzhong(at)whu.edu.cn
50
Majid Naeimi
Leibniz Univ. of Hannover
Germany
naeimi(at)mbox.ife.uni-hannover.de
51
Matt Amos
National Geodetic Office
New Zealand
mamos(at)linz.govt.nz
52
Mehmet Simav
Turkey
mehmet.simav(at)hgk.msb.gov.tr
53
Meng Yang
China
yangmeng(at)whigg.ac.cn
54
Michael Kuhn
Curtin University
Australia
M.Kuhn(at)curtin.edu.au
Tech. Univ. Munich
Germany
murboeck(at)bv.tu-muenchen.de
55
Michael
Murboeck
General
Command
of
Mapping
85
56
Min Jiang
China
jm(at)asch.whigg.ac.cn
57
Minkang Cheng
Univ. Texas at Austin-CSR
USA
cheng(at)csr.utexas.edu
58
Minzhang Hu
Institute of Seismology, CEA China
2009102140007(at)whu.edu.cn
Finnish Geodetic Institute
Finland
mirjam.bilker(at)fgi.fi
Mirko Reguzzoni
Politecnico di Milano
Italy
mirko.reguzzoni(at)polimi.it
Mohammad
Royal
Bagherbandi
Technology (KTH)
Sweden
mohbag(at)kth.se
K.N.Toosi Univ. Tech.
Iran
romeshkani(at)yahoo.com
Minia Univ.
Egypt
mstabdelbaky(at)gmail.com
Munawar Shah
Quaid-i-Azam Univ.
Pakistan
shahmunawar1(at)gmail.com
Nadezhda
Sternberg
Chujkova
Institute, MSU
Russia
nason(at)sai.msu.ru
66
Nasser Najibi
SHAO, CAS
China
nasser.najibi(at)yahoo.com
67
Nengfang Chao
Wuhan Univ.
China
nfchao(at)whu.edu.cn
Bulent Ecevit University
Turkey
nbavsar(at)gmail.com
Austria
norbert.kuehtreiber(at)tugraz.at
Denmark
oa(at)space.dtu.dk
Czech
otakar.nesvadba(at)gmail.com
59
60
61
62
63
64
65
68
69
70
71
70
Mirjam
Bilker-Koivula
Mohsen
Romeshkan
Mostafa
S.
Abd-Elbaky
Nevin
Betul
Avsar1
Institute
Astronomical
Norbert
Graz
Kuhtreiber
Technology
Ole
Baltazar
Andersen
Otakar Nesvadba
Ove Christian Dahl
Omang
73
Per Knudsen
74
Petr Holota
75
Qi Kang
of
University
of
DTU Space
Res.
Ins.
of
Gepdesy,
Topography & Cartography
Ove.Christian.Dahl.Omang(at)kartverket.
Geodetic Institute
Norway
DTU Space
Denmark
pk(at)space.dtu.dk
Czech
petr.holota(at)pecny.cz
China
kq(at)imech.ac.cn
Res.
Ins.
of
Gepdesy,
Topography & Cartography
Ins. Mechanics, CAS
86
no
76
Qiujie Chen
Tongji University
China
chenqiujie2009(at)163.com
77
Ramin Kiamehr
Zanjan University
Iran
kiamehr(at)kth.se
78
Rene Forsberg
Tech. Univ. of Denmark
Denmark
rf(at)space.dtu.dk
Politecnico di Milano
Italy
riccardo.barzaghi(at)polimi.it
79
Riccardo
Barzaghi
80
Robert Cunderlik
Slovak University of Techn.
Slovakia
cunderli(at)svf.stuba.sk
81
Robert Tenzer
Wuhan Univ.
China
rtenzer(at)sgg.whu.edu.cn
82
Roland Pail
Tech. Univ. Munich
Germany
pail(at)bv.tum.de
83
Rui Jin
SHAO, CAS
China
ruijin(at)shao.ac.cn
84
Shaobo Qu
HUST, Wuhan
China
qushaobo(at)hust.edu.cn_
85
Shaokun Cai
NUDT, Changsha
China
csk527(at)163.com
86
Shuanggen Jin
SHAO, CAS
China
sgjin(at)shao.ac.cn
87
Shuhua Ye
SHAO, CAS
China
ysh(at)shao.ac.cn
Tech. Univ. Munich
Germany
University Stuttgart
Germany
siavash(at)gis.uni-stuttgart.de
Federal University of Parana
Brazil
sfreitas(at)ufpr.br
Brazil
sfreitas(at)ufpr.br
Denmark
stco(at)alumni.dtu.dk
France
sylvain.bonvalot(at)ird.fr
88
89
90
91
Siavash
Ghelichkhan
Siavash
Iran-Pour
Silvio De Freitas
Silvio
R.C.
de Universidade
Freitas
Federal
do
Paraná- UFPR
Danmarks
Tekniske
sghelichkhani(at)geophysik.uni-muenche
n.de
92
Stefano Colpani
93
Sylvain Bonvalot
94
Tengyu Zhang
SHAO, CAS
China
zhangty(at)shao.ac.cn
95
Theresa Damiani
NOAA
USA
theresa.damiani(at)noaa.gov
96
Thomas Gruber
Tech. Univ. Munich
Germany
thomas.gruber(at)tum.de
97
Urs Marti
Federal
Universitet (DTU)
Bureau
Gravimétrique
International (BGI)
Office
of Switzerland
87
urs.marti(at)swisstopo.ch
Topography swisstopo
98
Vagner Ferreira
Hohai University, Nanjing
China
[email protected]
99
Vojtech Palinkas
Geodetic Observatory Pecny
Czech
vojtech.palinkas(at)pecny.cz
100
Wei Chen
Wuhan Univ.
China
wchen(at)sgg.whu.edu.cn
101
Wei Feng
China
fengwei(at)whigg.ac.cn
102
Wei Yu
Hefei Univ. Tech./SHAO
China
abcyuweiabc(at)163.com
103
Wenbin Shen
Wuhan Univ.
China
wbshen(at)sgg.whu.edu.cn
104
Wenjing Chen
Wuhan Univ.
China
cwjwhu(at)whu.edu.cn
105
Wenxin Zhang
Shanghai Univ./SHAO
China
396820933(at)qq.com
106
Wolfgang Keller
University Stuttgart
Germany
ac101133(at)gis.uni-stuttgart.de
107
Xiang Gu
Wuhan Univ.
China
rtenzer(at)sgg.whu.edu.cn
108
Xiaoli Deng
University of Newcastle
Australia
xiaoli.deng(at)newcastle.edu.au
109
Xiaomin Zhang
DFH Satellite Co. LTD
China
zhangxiaomin01(at)tsinghua.org.cn
110
Xiaopeng Li
NOAA
USA
xiaopeng.li(at)noaa.gov
111
Xin Zhao
Shanghai Univ./SHAO
China
75305860(at)qq.com
112
Xinggang Zhang
SHAO, CAS
China
zhangxinggang(at)shao.ac.cn
113
Xixuan Bai
China
baixx87(at)asch.whigg.ac.cn
114
Xuechuan Li
WHU/SHAO
China
leexc0124(at)163.com
115
Xuelin Tao
Hefei Univ. Tech./SHAO
China
studylin(at)163.com
116
Xuerui Wu
SHAO, CAS
China
xrwu(at)shao.ac.cn
117
Xuyang Hou
Beijing Univ. of Technology
China
hopor123(at)126.com
118
Yang Zhou
Shanghai Univ./SHAO
China
371877915(at)qq.com
119
Yansong Xue
SHAO, CAS
China
xys(at)shao.ac.cn
120
Yi Yang
SHAO, CAS
China
yiyang(at)shao.ac.cn
121
Yingchun Shen
China
shenyingchun12(at)mails.ucas.ac.cn
88
122
Yunlong Wu
Institute of Seismology, CEA
China
yunlongwu(at)gmail.com
123
Zebing Zhou
HUST, Wuhan
China
zhouzb(at)hust.edu.cn
124
Zhengtao Wang
Wuhan Univ.
China
ztwang(at)whu.edu.cn
125
Zhenwei Huang
China
huangzw(at)casm.ac.cn
Chinese
Academy
of
Surveying and Mapping
89
80 Nandan Road, Shanghai 200030, China
Website: http://www.shao.ac.cn

Program Handbook

Transcription

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