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LINKS BETWEEN THE ATMOSPHERIC ENVIRONMENT AND CIRRUS PROPERTIES:
A SYNERGETIC APPROACH USING IR SOUNDERS, ACTIVE SOUNDERS AND
METEOROLOGICAL REANALYSES
C. Stubenrauch, A. Feofilov, T. Nicolas, and R. Armante
Laboratoire de Météorologie Dynamique, IPSL/CNRS, Université de Pierre et Marie Curie, Ecole Polytechnique, France
E-mail:[email protected]
How many of detected clouds are high, midlevel & low clouds?
Climate monitoring with IR Sounders
TOVS, ATOVS, AIRS, CrIS,
>1979
/ ≥ 1995 NOAA
IASI (1,2,3),
≥2002 / ≥ 2012 NASA
IASI-NG
≥2006 / ≥ 2012 / ≥ 2020 CNES-EUMETSAT
1:30 AM/PM,
(2005-2012)
1rst coordinated intercomparison of 12 ‘state of the art’ global cloud datasets
onboard polar orbiting satellites, with local observation time at:
7:30 AM/PM,
Cloud Assessment
TOVS Path-B & AIRS-LMD participated in
Stubenrauch et al., BAMS 2013
http://climserv.ipsl.polytechnique.fr/gewexca
9:30 AM/PM
CAHR = CAH / CA
satellite observations: good spatial coverage
long time series -> climate studies
channels along CO2 / H2O absorption bands (with differing atmospheric weighting)
allow to sound the atmosphere
retrieval day & night: T & H2O profiles; cloud, aerosol & surface properties
high spectral resolution: esp. reliable Cirrus properties
increasing spectral resolution
CAHR + CAMR + CALR = 1
CAHR depends on sensitivity to thin Ci (30% spread)
active lidar > IR sounders > VIS-NIR-IR imagers > multi-angle VIS imagers
42% are high clouds (COD>0.1)
-> 20% with COD>2 (MISR, POLDER)
thin Ci over low cloud misidentified as midlevel clouds by ISCCP, ATSR,
POLDER
42% are single-layer low clouds,
60% are low clouds (MISR, CALIPSO, surface observer)
-> increasing vertical resolution of upper tropospheric humidity
TOVS: TIROS Operational Vertical Sounder : High resolution InfraRed Sounder (HIRS) / Microwave Sounding Unit (MSU)
ATOVS: Advanced TIROS Operational Vertical Sounder: HIRS / Advanced Microwave Sounding Unit (AMSU)
AIRS: Atmospheric InfraRed Sounder + AMSU
CrIS: Cross-track Infrared Sounder + Advanced Technology Microwave Sounder (ATMS)
IASI: Infrared Atmospheric Sounding Interferometer
CALIPSO only considers uppermost layers
to better compare with passive datasets
lidar, CO2 sounding, IR spectrum
Ci over low clouds: interpretation of cloud height
IR-VIS imagers
solar spectrum
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TOVS Path-B & AIRS-LMD L3 cloud data available at http://ara.abct.lmd.polytechnique.fr/
AIRS-LMD L2 cloud data distributed by ICARE: http://www.icare.univ-lille1.fr/
( 20% of all cloud scenes according to CALIPSO)
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even if absolute values differ,geographical distributions & seasonal cycles similar
Diurnal cycle of high clouds
Cloud Retrieval: choice of ancillary data
AIRS- IASI : using similar ancillary data reduces biases (diurnal cycle = small signal)
reanalysis of AIRS, IASI (LMD) & TOVS / ATOVS (cooperation CM-SAF)
ISCCP analysis : max of high clouds in evening (significant over tropical land) (Cairns 1995)
TOVS analysis : Cirrus increase during afternoon & persist during night, thickening (Stubenrauch et al. 2006)
LMD cloud retrieval based on spectral coherence of cloud emissivities estimated from radiances along CO2
absorption band (4A radiative transfer, TIGR data base)
GEWEX ancillary data
Dec 2007
Analysis 5° x 5°: time series, RMS of
diurnal variability
ERA ancillary data
clear sky radiance = f(Tsurf, esurf, t(l,atm,qv))
AIRS,
1:30AM
NASA AIRS L2 (V6) & NOAA IASI L2, GEWEX (NOAA HIRS-NN, ISCCP Tsurf), ERA-Interim
Impact on CP distributions:
IASI,
9:30AM
land, 1h30PM
0
0.1
0.15
0.2
main diurnal variability over tropical land
coherent with Cairns 1995, Tian et al. 2003
AIRS,
1:30PM
CP distributions similar for AIRS L2 / ERA, slightly less high clouds & more low clouds for GEWEX
(GEWEX warmer Tsurf in afternoon)
0.05
IASI,
9:30PM
3
4
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CEM-CP high-cloud Weather States
Identification of cloud classes
cloud pressure (CP) & optical depth (COD) or cloud emissivity (CEM)
vertical extent ISCCP
per cloud class:
CEM class :
0.05-0.25
0.25-0.5
0.5-0.75
0.75-0.9
0.9-1
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Clouds extended objects, driven by dynamics -> cloud systems
AIRS-LMD
mesoscale grid: occurrence of these classes -> weather states (Tselioudis et al. 2013; talk W. Rossow)
42 CEM-CP classes -> 13 CEM-CP Weather States; 5 including high clouds:
CEM
vertical extent increases with CP & CEM;
similar contributions of single layer Ci & Ci + low cld
vertical structure per cloud class
0.7 / 98 / 3
0.8 / 97 / 6
0.7 / 96 / 6
0.4 / 98 / 6
0.6 /65 / 9
CEM/CA/ RFO
Vertical structure from CALIPSOCloudSat GEOPROF (Mace et al. 2009)
Cloud types like in Tselioudis
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WS’s distinct vertical & horizontal structures
Clouds with same IWP may have different IWC and De profiles
-> influence on radiation ?
Is it possible to give a shape probability in dependence of cloud properties or atmospheric
properties?
const
trapecia
increas
decreas
51
0-10
54%
20%
10%
16%
29
10-30
31%
48%
13%
8%
17
30-100
28%
56%
14%
3%
3
100-300
26%
51%
21%
2%
<1
300-1000
38%
35%
26%
1%
only strong vertical winds affect lower & upper triangles
probability of ISS presence in layer
by calibration with MOZAIC (commercial aircraft)
200-250 hPa
Feofilov et al., in prep.
RFO
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Ice Supersaturation & Cirrus
IWC profile classes & dependency on IWP
IWP(g/m2)
Next step: explore radiative effects
frequency of potential contrail situations
from CALIPSO
AIRS
const & trapecia ≈ 80% of all
profiles
Lower triangle increases with
IWP from 10 to 26%
from AIRS
Lamquin 2009; Lamquin et al., ACP 2012
integrated from ice super saturation occurrence
weighted by flight altitude air traffic density
Ci occurrence increases with ISS occurrence
stronger increase in tropics than in midlat
(different formation mecanism?)
Upper triangle only for IWP <
30 g/m2
independent
of location / season !
Next steps:
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•Lagrangian studies of atmospheric flow linked to cirrus (like Luo & Rossow 2004, Tzella & Legras 2011)
• link ISS & dust loading to Ci
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