2011/2012 of glaciers in the Patagonia Icefields from TanDEM

Transcription

Volume changes 2000 – 2011/2012 of glaciers in the Patagonia Icefields from TanDEM‐X and SRTM data
Wael Abdel Jaber1, Dana Floricioiu1, Helmut Rott2, Björn Sass³
1) German Aerospace Center (DLR), Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, Germany
2) Institute for Meteorology and Geophysics, University of Innsbruck, Austria
3) Friedrich‐Alexander‐Universität, Erlangen, Germany
TanDEM‐X Science Team Meeting, Oberpfaffenhofen, Germany, 12 – 14 June 2013
The South Patagonia Icefield (SPI)
 SPI extension: 350 km N‐S. Mean width: 35 km.
 First glacier inventory by Aniya et al. (1996):
• 48 major outlet glaciers (see map)
North Patagonia Icefield (NPI)
Lat: 73°35’ W
Lon: 46°20’ to 47°40’ S
Area: 4,200 km²
South Patagonia Icefield (SPI)
Lat: 73°30’ W
Lon: 48°20′ to 51°30′ S
Area: 13,000 km2
• 100+ small cirque and valley glaciers
 Most major glaciers calving into:
• freshwater lakes
NPI
SPI
GCN
• Pacific ocean fjords
CD
 Most of major glaciers exhibit strong mass loss
trends over the last decades, except Pio XI and
Perito Moreno.
[1] Jacob T. et al, „Recent contributions of glaciers and ice caps to sea level rise“, Nature, 2012 Remote Sensing Technology Institute
Aniya et al., 1996
Source: www.glaciologia.cl
 Confirmed by low resolution mass trends obtained
by GRACE gravity fields analysis [1].
2
SRTM & TanDEM‐X data
 Well suited multitemporal elevation dataset for mass balance estimation:
• Both DEM from SAR bistatic interferometry
• Both DEMs acquired in a relatively short time span • Temporal baseline: 11‐12 years  allows detecting slower changes in elevation
 SRTM
• Acquisition: 11 ‐ 22 February 2000
• C‐band DEM: USGS release 2.0 calibrated with ICESat altitude tie points (DFD) [1]
 TanDEM‐X
• Integrated TanDEM‐X Processor (ITP): CoSSC data  RawDEMs
• 19 RawDEMs (of which 4 with dual baseline phase unwrapping) (17 desc., 2 asc.)
‐ 2011: 8 scenes in austral summer + 2 scenes in winter
‐ Early 2012: 9 scenes in summer
 Issues:
• Accurate coregistration of both DEMs
• Possible biases in DEM difference due to different DEM spatial resolution
• Radar signal penetration in ice/snow related to:
‐ physical parameters of snow and ice (liquid water content, ice compactness, …)
‐ system parameters (radar frequency, incidence angle)
Remote Sensing Technology Institute
[1] Felbier A., “Ausgleichung langwelliger Höhenfehler in SRTM mit Kugelflächenfunktionen 3
auf Basis ausgewählter ICESat‐Daten”, TUM, 2009
Ice and snow surface conditions
During SRTM
During TanDEM‐X
QuikSCAT: Ku‐band backscattering (σ0) SIR products*: Active channel of bistatic acquisition:
X‐band backscattering (σ0)
0
SPI
‐5
P. Moreno Gl.
‐15
σ0 [dB]
‐10
‐20
‐25
‐30
10‐13 Feb. 2000
14‐17 Feb. 2000
18‐21 Feb. 2000
Feb. 2000 (summer): ‐10 < σ0 < ‐20 dB  wet glacier surface 17 Feb. 2011 (winter scene)
σ0 < ‐7 dB on glacier plateau (θi= 39°)  wet glacier surface TDM acquisitions mostly in summer, only 2 acquisitions in winter
SRTM and TanDEM‐X acquired with wet conditions on the firn area  penetration depth is negligible
* Courtesy Matthias Reif, IMGI, Univ. of Innsbruck
4
Applied procedure for dh/dt derivation
TDM scene
CoSSC pair
ITP
TDM RawDEM
Coregistered
SRTM DEM
- SRTM on ice free areas
RawDEM
validation
OK?
- ICESat GLAS tracks (2003-2009)
- Overlapping TDM scenes
no
new APO
estimation
yes
TDM RawDEM
∆h ∆h/∆t
- RawDEM Flag Mask (FLM)
- Thresholding ∆h image
- Manual selection
PU error
masking
ITP: Integrated TanDEM‐X Processor
APO: Absolute Phase Offset
PU: Phase Unwrapping
Mosaicking
5
N
Jorge Montt
SPI: ice elevation change rate 2000 – 2011/2012
 Most glacier termini (0 – 1400m) display a significant thinning
trend
 Exceptions: Pio XI and Perito Moreno
Occidental
O‘ Higgins
 On the plateau (1400 – 3600 m): thinning signal in the N‐E part
and equilibrium on West side and South sector
Pio XI
Viedma
Upsala
+8
Ameghino
P. Moreno
+4
0 m a‐1
Grey
‐4
Tyndall
0
25
50
km
‐8
6
Perito Moreno and Ameghino: ice elevation change 2000 ‐ 2011
Perito Moreno (area: 258 km²)
N
 front stable with periodical damming events
 no significant elevation changes
Ameghino (area: 76 km²)
 Front in retreat
∆h=‐70 m
• ‐0.8 km (72.7 m a‐1) [2000‐’11] Ameghino Gl.
• ‐3.5 km (152 m a‐1) [‘70‐’93] : large proglacial lake
ICESat
 Significant surface lowering mostly below equilibrium line
∆h=‐20 m
• ‐6.4 m a‐1 [2000‐’11] near current front
• ‐2.3 m a‐1 [‘49‐’93] near ‘93 snout (Aniya et al., ‘96)
Perito Moreno Gl.
+100
Ameghino
P. Moreno
+50
‐5.3 m a‐1
0m
‐8.5 m a‐1
‐50
‐100
7
Pio XI: ice elevation change 2000 ‐ 2012
N  Largest calving glacier of SPI  Area: 1265 km². Length: 64 km.
 Tidewater glacier
∆h=+40 m
 Front advance: +1.97 km [2000 ‐ 2012] (180 m a‐1)
1.97 km
Front: Feb. 2000
Front: Feb. 2012
+100
∆h=+50 m
∆h=+15 m
+50
0m
 Only main glacier with increased surface elevation trend
 ∆h > +50 m (+4.4 ma‐1) at 4.5 km from front
 Slight elevation increase on upper part: ∆h = +15 m (+1.25 ma‐1)
‐50
‐100
 Average ice thickening on ablation area: +2.2 ma‐1 [‘75‐
’95] (Rivera and Casassa, 1999)
8
Jorge Montt Glacier: ice surface thinning and front retreat
 Area: 500 km². Length: 41 km.
 Ice thinning up to 18 ma‐1 concentrated below 900 m a.s.l. (near equilibrium line) where the glacier flows in a steep bed and temperatures are higher. Front retreat: 1.9 km (173 ma‐1).
 Thinning rate of ‐3.3 ma‐1 (average on whole glacier) and ‐18 ma‐1 at lower elevations [1975 –
2000]. Front retreat: ‐8.5 km (340 ma‐1) (NASA, CECS)
 Front retreat >800 ma‐1 [Feb. 2010 – Jan. 2011] (Rivera et al. [1])
Centro de Estudios Cientificos (CECS), Chile
[1] Rivera, A., Koppes, M., Bravo, C., Aravena, J. C., “Little Ice Age advance and retreat of Glaciar Jorge Montt, Chilean
Patagonia”, Climate of the Past, 8, pp. 403‐414, 2012.
9
Jorge Montt: ice elevation change 2000 ‐ 2011
Front Feb. 2000
A
1.9 km
Front May 2011
(3)
N
(2) ∆h=‐120 m
H=603 m
+250
B
(1) ∆h=‐98 m
H=790 m
B
+125
(3) ∆h=‐28 m
H=1300 m
0m
(1)
(2)
‐125
ICESat
‐250
A
Front retreat 1.9 km
10
N
Jorge Montt
Glacier mask and Area Elevation Distribution
 SRTM DEM (yr. 2000) used as reference
 Glacier mask: improvement of Randolph Glacier Inventory (RGI) with: • LANDSAT 7 ETM (year: 2001‐2003)  NDSI = (b2‐b5)/(b2+b5)
• SRTM DEM (glacier fronts)
Occidental
O‘ Higgins
 Glacier area (yr. 2000)  12870 km²
Pio XI
Viedma
3600
Ameghino
P. Moreno
2700
1800
Grey
SRTM
DEM
yr. 2000
0
25
Area – Elevation Distribution (AED) for SRTM DEM (2000)
AED yr. 2000
AED yr. 2000 for TDM coverage
Area [km²]
Upsala
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
900
Tyndall
50
km
Bin area > 80 km²
0 m
Altitude [m]
11
N
Jorge Montt
Glacier mask and Area Elevation Distribution
 SRTM DEM (yr. 2000) used as reference
 Glacier mask: improvement of Randolph Glacier Inventory (RGI) with: • LANDSAT 7 ETM (year: 2001‐2003)  NDSI = (b2‐b5)/(b2+b5)
• SRTM DEM (glacier fronts)
Occidental
O‘ Higgins
Pio XI
 Glacier area (yr. 2000)  12870 km²
 Glacier area covered with TDM data  11940 km² (92.8%)
 Glacier area with missing TDM data  930 km² (7.2%)
Viedma
Ameghino
P. Moreno
Grey
Tyndall
0
25
50
km
Area – Elevation Distribution (AED) for SRTM DEM (2000)
Glacier area not covered by TDM (%)
AED yr. 2000
Glacier area not covered by TDM (%)
AED yr. 2000 for TDM coverage
Area [km²]
% Upsala
1400
100
1300
90
1200
80
1100
1000
70
900
60
800
700
50
600
40
500
30
400
300
20
200
10
100
0
Bin area > 80 km²
Altitude [m]
12
N
Jorge Montt
SPI: mass balance
 Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM
Occidental
O‘ Higgins
Pio XI
Viedma
Mean Elevation Change Rate (dh/dt)
4
3
Upsala
250
+4
0
m a‐1
Grey
200
1
150
0
‐1
100
‐2
50
‐3
0
Tyndall
0
25
50
km
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
‐4
‐4
Area [km²]
+8
dh/dt [m/yr]
2
Ameghino
P. Moreno
300
Mean Elevation Change Rate
Area Elevation Distribution yr. 2000
Altitude [m]
‐8
13
N
Jorge Montt
Occidental
O‘ Higgins
Pio XI
SPI: mass balance




Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM
Mean dV/dt = (dh/dt) * (AED of yr 2000)  scaling data up to entire glacier surface
Ice density  ρice= 900 kg/m³
dM/dt = (dV/dt) * ρice. Overall mass balance:
Time period
SPI total area
Area covered by Mean dh/dt (area Total dV/dt
TDM
weighted)
Total dM/dt
2000 –
2011/‘12
12868.15 km²
11941.78 km²
‐10.444 Gt/yr
‐0.902 m/yr
‐11.605 km³/yr
Viedma
Mean Volume Change Rate (dV/dt)
0,3
Mean Volume Change Rate
0,2
+8
Ameghino
P. Moreno
+4
dV/dt [km³/yr]
Upsala
0,1
0
‐0,1
‐0,2
0
m a‐1
Grey
25
50
km
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
Altitude [m]
Tyndall
0
1400
1200
1000
800
600
400
‐4
200
0
‐0,3
‐8
14
N
Jorge Montt
Occidental
O‘ Higgins
Pio XI
SPI: mass balance




Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM
Mean dV/dt = (dh/dt) * (AED of yr 2000)  scaling data up to entire glacier surface
Ice density  ρice= 900 kg/m³
dM/dt = (dV/dt) * ρice. Global mass balance:
Time period
SPI total area
Area covered by Mean dh/dt (area Total dV/dt
TDM
weighted)
Total dM/dt
2000 –
2011/‘12
12868.15 km²
11941.78 km²
‐10.444 Gt/yr
‐0.902 m/yr
‐11.605 km³/yr
Viedma
Mean Mass Change Rate (dM/dt)
0,25
Mean Mass Change Rate
0,2
0,15
Upsala
+8
Ameghino
P. Moreno
+4
dM/dt [Gt/yr]
0,1
0,05
0
‐0,05
‐0,1
‐0,15
0 m a‐1
Grey
‐0,2
25
50
km
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
Altitude [m]
Tyndall
0
1400
1200
1000
800
600
400
‐4
200
0
‐0,25
‐8
15
Gran Campo Nevado (53°S): ice elevation change
N
E
W
S
h
Analysis by: Björn Sass, FAU Erlangen  Area GCN Icefield + adjacent glaciers [2007]: 252.6 km² (Schneider et al, 2007)
1.1 km
∆h=‐80 m
Noroeste Gl.




TanDEM‐X: 2 descending scenes, dual baseline processing
Temporal baseline: Feb. 2000 – Feb. 2012 Front retreat of Noroeste Glacier: ‐1.1 km (‐91.6 ma‐1)
∆h = ‐80 m (6.7 ma‐1) near main calving front of Noroeste
Glacier (100 m a.s.l.)
16
Conclusions
 TanDEM‐X and SRTM data were used to derive temporal trends of ice elevation
change in the SPI and GCN for the period 2000 – 2011/’12.
 An overall mass balance was derived, necessary for estimating the contribution of the
Patagonia Icefields to sea level rise.
 Contrasting behavior is observed on different glaciers with respect to changes in ice
elevation and front position. This emphasizes the importance of spatially detailed
repeated observations in order to understand the complexity of glacier response to
climate change.
 The method will be applied to the remaining Patagonian icefields (NPI, Cordillera
Darwin).
 Near future work:
• Error budget estimation for the DEM difference
• Estimation of ice mass loss due to frontal retreat, including subsurface ice loss
Thank you for your attention!
17
Upsala: ice elevation change 2011 ‐ 2000
 Front retreat: ‐3.4 km [Feb. 2000 – May 2011] (0.3 m a‐1)
N
 ∆h > ‐160 m (14.5 m a‐1) near main calving front
 ∆h ~ ‐110 m (10 m a‐1) on tributaries Bertacchi and Cono
 ∆h = ‐30 to ‐40 m (10 m a‐1) near equilibrium line (1200 m a.s.l)
 Dynamic thinning due to acceleration and large calving events.
Viedma Gl.
 Field survey: ‐9.5 to ‐14 m a‐1 [‘91 ‐ ‘93] (Naruse et al., 1997)
∆h=‐50 m
ICESat
+80
Cono Gl.
Upsala Gl.
+160
Bertacchi Gl.
∆h=‐35 m
0m
Cono Gl.
∆h=‐160 m
Bertacchi Gl.
‐80
3.4 km
‐160
18
Grey, Tyndall, Asia, Amalia: ice elevation changes
N
 Tyndall Gl.: • ‐6.3 ma‐1 on terminus [2000‐’11] • ‐4.9 ma‐1 average [’93‐’99] (Raymond et al. 2000)
Frias
∆h=‐55 m
 Grey Gl.:
Asia
∆h=0 m
Amalia
∆h=‐10 m
Grey
∆h=‐60 m
• ‐5.4 ma‐1 on east terminus
• ‐3.6 ma‐1 on main terminus
• ‐6.5 ma‐1 on west terminus
+100
HPS 38
∆h=‐65 m
+50
Photo: Dana Floricioiu, DLR
0m
Grey Glacier, front.
‐50
HPS 38
∆h=‐75 m
Tyndall
∆h=‐70 m
‐100
19
O’ Higgins, Bernardo, Occidental: ice elevation changes
Bernardo ∆h=‐50 m
Bravo
∆h=‐75 m
N
Tempano
∆h=‐50 m
Occidental
∆h=‐55 m
O’ Higgins
∆h=‐25 m
Greve
∆h=‐45 m
+100
+50
HPS 8
∆h=‐120 m
0m
HPS 9
∆h=‐30 m
Chico
∆h=‐35 m
‐50
‐100
 O’ Higgins: ‐2.5 ma‐1 on terminus [2000‐’12]
 Glacier with strong historical retreat trend: 14.6 km during the period 1896 ‐ 1995 (Casassa et al. , 1997)
20
SPI ice elevation and volume change 2000 – 2011/2012
Total SPI area [km2]
Area covered by TanDEM‐X [km2]
12826.39
11354.67
Time period
Volume
change rate [km3
yr‐1]
Mass change rate [Gt yr‐1 ]
2000 ‐
2011/12
‐11.83
‐10.65
Volume change rate [km3
yr‐1]
Mass change
rate [Gt yr‐1 ]
Author
Data source
Area
covered
Time period
Jacob et al, 2012
GRACE
SPI and NPI
Jan. 2003 ‐
Dec. 2010
‐23 ± 9
Ivins et al, 2011
GRACE
SPI and NPI
Jan. 2003 –
Mar. 2009 ‐26 ± 6
Rignot et al, 2003
DEM diff. (cartogra
phy & SRTM)
SPI
1975 ‐ 2000
1995 ‐ 2000
‐13.0 ± 0.8 Willis et al, GRL, 2012 DEM diff (ASTER & SRTM)
SPI
NPI
2000 – 2012
2000 – 2011
‐22.2±1.3
‐4.9±0.3
‐38.7 ± 4.4
EO & cryosphere science, ESA ESRIN, Frascati, 13‐16 Nov.2012
‐20.0 ± 1.17
‐4.4 ± 0.27 21
Perito Moreno and Ameghino: ice velocities
N
 Area: Perito Moreno: 258 km², Ameghino: 76 km².
 Ice velocity map
• 3 May 2011 / 14 May 2011 (11 days)
 P. Moreno and Ameghino: Ameghino Gl.
• light seasonal variability
• constant annual mean velocity (2008‐
2012)
• agreement with GPS and InSAR [1]
Perito Moreno Gl.
6.0
3.0
m/day
4.5
1.5
0.0
Photo: H. Steinberg
[1] Stuefer, M., H. Rott, and P. Skvarca, “Glaciar Perito Moreno,
Patagonia: climate sensitivities and glacier characteristics preceding
the 2003/04 and 2005/06 damming events,” Journal of Glaciology, 53
(180), pp. 3‐16, 2007.
22
Upsala Glacier: ice velocities
January 2008
October 2008
May 2009
October 2009
Upsala Glacier
area: 902 km²
N
July 2010
March 2011
October 2011
10.0
7.5
5.0
m/day
February 2010
2.5
2.1 km
Front: Jan. ‘08
0.0
23
Pio XI: ice velocity
5.0
3.75
2.5
m/day
N
1.25
0.0
 Largest calving glacier of SPI  Area: 1265 km². Length: 64 km.
 Tidewater glacier
 Ice velocity map
• 3 May 2011 / 14 May 2011
• Velocities from 1 to 5 md‐1 at the bend.
Photo: Ralf Rosenau, TU Dresden
24
Shuttle Radar Topography Mission (SRTM)




NASA/DLR mission: semi‐global DEM by means of single pass interferometry
Acquisition: 11 ‐ 22 February 2000
Coverage: 56°S to 60°N
Bistatic interferometric system:
• C‐band: full coverage
• X‐band: partial coverage (gaps)
 C‐band DEM spatial posting: 3 arcsec (90 m)
 Nominal vertical accuracy (90% linear point‐to‐point error):
• Relative: 10 m / Absolute: 16 m  Nominal horizontal accuracy (90% circular error):
• Relative: 15 m / Absolute: 20 m
 DEM available at DFD is calibrated with ICESat altitude tie points  increased accuracy
 ICESat (Ice, Cloud, and land Elevation Satellite)  NASA mission 2003 ‐ 2009
• Geoscience Laser Altimeter System (GLAS) space borne LIDAR altimeter
• Footprint: 65 m of diameter. Sampling distance: 170 m.
25
TanDEM‐X and ITP
 Objective: global DEM by means of single pass interferometry
 Bistatic interferometric system in X‐band
 Launch: June 2010
 Nominal relative vertical accuracy (90% linear point‐to‐point error): 2 m (less than 20% slopes), 4 m (more than 20% slopes)
 Nominal relative horizontal accuracy (90% circular error): 4 m
 Integrated TanDEM‐X Processor (ITP) used to generate RawDEMs from CoSSC data
 RawDEM mean asbolute vertical error globally below 3 m
 19 RawDEMs processed with ITP (acquired: 2011 and early 2012)
• 4 RawDEMs  dual baseline phase unwrapping
2100 m
TanDEM‐X DEM:
O’ Higgins Glacier (SPI)
300 m
26

2011/2012 of glaciers in the Patagonia Icefields from TanDEM

Transcription

Similar documents

Kapitel 2.C

pawprints - Queen City Dog Training Club