Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing
description
Transcript of Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing
![Page 1: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/1.jpg)
Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for
the GERB data processing
Nicolas Clerbaux & RMIB GERB Team.
GIST 26, RAL
3 and 4 May 2007
![Page 2: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/2.jpg)
MSG1 -> MSG2 transition
New GERB instrument but also new SEVIRI imager
• Are the SEVIRI scene identifications consistent?
– GERB unfiltering
– GERB SW ADM selection– GERB LW angular modelling
– GERB scene identification– GERB dust flag and AOD retrieval
• Are the GERB-likes (SEVIRI NB-to-BB) consistent?
– RGP GERB geolocation
– GERB unfiltering
– GERB resolution enhancement
– use of GERB-like data for monthly means
![Page 3: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/3.jpg)
Structure of the talk
• Intercomparison of level 1.5 SEVIRI data– reflectance for visible channels– BT and radiance for thermal channels
• Intercomparison of GERB scene identification– cloud fraction, – cloud optical depth – cloud phase– clear sky reflectance– LW anisotropic factor– dust flag and AOD retrieval
• Intercomparison of the GERB-like BB quantities– solar and thermal radiances– solar and thermal fluxes
• Conclusions
![Page 4: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/4.jpg)
The MSG1 and MSG2 data look very similar...
“natural color” “air mass”
![Page 5: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/5.jpg)
Visible bands spectral response and effective central wavelength for MSG-1 and
MSG-2
MSGs=0.639µm
MSG2s=0.640µm
MSGs=0.809µm
MSG2s=0.807µm
MSGs=1.635µm
MSG2s=1.635µm
![Page 6: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/6.jpg)
0.6 µm reflectance intercomparison
ratio MSG2/MSG1
![Page 7: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/7.jpg)
0.6 µm reflectance intercomparison – saturations for MSG2
Max 0.6 µm reflectance at nadir and d=1 A.U. is
MSG1 : 1.082
MSG2 : 0.942
Software fix: accept saturation if SZA<20°
![Page 8: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/8.jpg)
0.8 µm reflectance intercomparison
ratio MSG2/MSG1
![Page 9: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/9.jpg)
1.6 µm reflectance intercomparison
ratio MSG2/MSG1
![Page 10: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/10.jpg)
6.2 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 11: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/11.jpg)
7.3 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 12: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/12.jpg)
8.7 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 13: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/13.jpg)
9.7 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 14: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/14.jpg)
10.8 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 15: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/15.jpg)
12 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 16: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/16.jpg)
13.4 µm brightness temperature intercomparison
ratio MSG2/MSG1
![Page 17: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/17.jpg)
Spectral radiance comparison
ratio MSG2/MSG1
• WV 6.2 : 1.002• WV 7.3 : 0.992• IR 8.7 : 0.999• IR 9.7 : 0.994• IR 10.8 : 1.000 • IR 12.0 : 0.996• IR 13.4 : 0.974
-> in general MSG-2 is close or a bit lower than MSG-1, CO2 is significantly lower
![Page 18: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/18.jpg)
Summary for level 1.5 MSG-2/MSG-1 intercomparison
• visible 0.6µm and 0.8µm channels : 1 to 2% higher reflectance
• near IR channel (1.6µm): very close• thermal channels: very close or a bit lower except the
CO2 channel (13.4µm) which is significantly colder (0.5% in BT , 2.5% in radiance)
• 0.6µm is often saturated over thick cloud• residual stripes in the WV 6.2µm channel
![Page 19: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/19.jpg)
Intercomparison of scene identification
• surface type is exactly the same (same rectification grid)• cloud fraction• cloud optical depth• cloud phase• clear sky reflectance images• LW angular modeling• Helen Brindley 's dust flag• Aerosol retrieval with Ignatov look-up-table for the
0.6µm, 0.8µm and 1.6µm channels
![Page 20: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/20.jpg)
Cloud fraction
![Page 21: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/21.jpg)
Cloud optical depth (log)
![Page 22: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/22.jpg)
Cloud phase (0=pure water 1=pure ice)
![Page 23: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/23.jpg)
Clear sky reflectance intercomparison (ratio to model)
VIS 0.6 VIS 0.8
![Page 24: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/24.jpg)
LW ADM due to the change in NB radiances
F= L / R(,L6.2
, L10.8
, L12
,L13.4
)
FMSG1'
/FMSG1
Ratio of the flux for a same BB radiance L but for simulated differences between MSG1 and MSG2 NB radiances in the 6.2µm, 10.8µm, 12µm, 13.4µm channels
Small increase of the anisotropy (0.2%).
![Page 25: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/25.jpg)
MSG2 MSG1Dust Flag
![Page 26: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/26.jpg)
AOD in 0.6 µm channel
![Page 27: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/27.jpg)
AOD in 0.8 µm channel
![Page 28: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/28.jpg)
AOD in 1.6 µm channel
![Page 29: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/29.jpg)
Summary for scene identification
• cloud fraction very similar• cloud optical depth slightly higher (2%) due to the 0.6µm
and 0.8µm reflectances• cloud phase very similar• LW angular modelling close, small difference in the “good
direction” (increase of the limb-darkening). • dust flag may differ in some semi-transparent situations • AOD 2% higher at 0.6µm , 0.6% higher at 0.8 µm and
1.6% lower at 1.6 µm. Ratio of AOD does not correspond to ratio in reflectance.
![Page 30: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/30.jpg)
Intercomparison of broadband quantities
• GERB-like BB radiances (NB->BB)– reflected solar– emitted thermal
• GERB-like BB fluxes (NB->BB + ADMs) – reflected solar– emitted thermal
![Page 31: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/31.jpg)
GERB-like Reflected Solar Radiance
![Page 32: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/32.jpg)
GERB-like Emitted Thermal Radiance
![Page 33: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/33.jpg)
GERB-like Reflected Solar Flux
ratio MSG2/MSG1
![Page 34: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/34.jpg)
GERB-like Emitted Thermal Flux
ratio MSG2/MSG1
![Page 35: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/35.jpg)
Summary for the broadband products
• solar radiance MSG2/MSG1 = 1.012• thermal radiance MSG2/MSG1 = 0.9964• solar flux MSG2/MSG1 = 1.012• thermal flux MSG2/MSG1 = 0.9954
![Page 36: Intercomparison of SEVIRI data from MSG1 and MSG2 and implications for the GERB data processing](https://reader036.fdocuments.net/reader036/viewer/2022062518/56814967550346895db6b9db/html5/thumbnails/36.jpg)
Conclusions and future work
• start of GERB-1 processing with SEVIRI on MSG2• good consistency with MSG1, most of the
differences are explained by the level 1.5 SEVIRI data intercomparison,
• GERB-like radiances and fluxes are a bit closer to the actual GERB products
• To be done: analysis of the influence of the SEVIRI radiance definition (change from spectral radiance to effective radiance in April 2008).