Federal Department of Home Affairs FDHAFederal Office of Meteorology and Climatology MeteoSwiss
Verification of global radiation of COSMO-7 with MSG (Meteosat Second Generation)
and ASRB network (Alpine Surface Radiation Budget)
Matteo Buzzi [presented by Francis Schubiger]MeteoSwiss
COSMO General Meeting 2007
WG5 Parallel Session 18 September 2007
2 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
MSG processing chain: Introductionwork of CM-SAF (B. Dürr, MeteoSwiss)
• Usage of full spatial and temporal resolution of MSG satellites (pixel: ~ 1.1km x 1.8km, 15min)
• Processing for sun elevation angles > 5° only• Combination of 4 SEVIRI channels with High
Resolution Visible (HRV) channel and their temporal evolution improves the distinction of clouds over snow covered areas
• Estimation of surface incoming solar (SIS) radiation with HELIOSAT-1 Cloud-Index method
• No input data necessary from NWP/GCM models
Photo: ESA
3 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Verification data
Meteosat Second Generation• Daily averages• shadowing effects considered• Resolution: 1.1x1.8 km• Interpolated on COSMO grid• Domain:
ASRB (Alpine Surface Radiation Budget) network
• Daily averages• 10 stations mostly in the Swiss
Alps• Gridpoint to surface station
association: neighbouring gridpoint chosen
Monthly mean SIS-DEM, December 2004 [B. Dürr]
4 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Radiation validation: Alpine Surface Radiation Budget (ASRB) network
ASRB network consists of 10 sites (status October 2006)
5 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
ASRB station Gornergrat, 3110 m asl
Photo: Rolf Philipona, MeteoSwiss
6 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
July 2006
Global radiation: daily averages (sun elevation > 5°)
Comparison with MSG and ASRBMean error -Verification with MSGRed crosses: clear sky gridpoints & pixelsError bars: stdev errors
no bias for clear sky conditions in Summer, but clouds too less opaque (clouds too transparent)
7 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Cloudiness verification with SYNOPSummer 2006 : bias for +63..+72h
Pirmin Kaufmann, MeteoSwiss
8 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Cloudiness verification with ANETZSummer 2006 : mean diurnal cycle
Mean diurnal cycle bias / std dev / rms
9 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
December 2006
Global radiation: daily averages (sun elevation > 5°)
Comparison with MSG and ASRBMean error -Verification with MSGRed crosses: clear sky gridpoints & pixelsError bars: stdev errors
negative bias for clear sky conditions in Wintertime
10 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
December 2006: only pixels with fog
Mean error -Verification with MSG
Global radiation: daily averages (sun elevation > 5°)
positive bias at pixels with fog
11 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
24.12.2006 12 UTC MODIS
12 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
global radiation: hourly values April 06 – March 07for clear sky conditions in COSMO-7 & ANETZ
Vanessa Stauch, MeteoSwiss
13 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
downward longwave radiation: Payerne @ 23 UTCclear-sky cases 1999-2001: COSMO-7 and MODTRAN vs ASRB
Dürr et.al., 2005: Meteorol. Z., 14, 47-55
84 clear-sky nights 54 cases
14 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Downward longwave radiation: five COSMO-2 runs Winter 06/07
Mean error - Verification with ASRB
without topographic corrections
with topographic corrections
with subgrid topographic corrections
15 Verification of radiation with MSG & ASRB: Matteo Buzzi [presented by Francis Schubiger]
Summary
• Global radiation:• no bias for clear sky conditions in summertime, but
clouds too less opaque, resp. too transparent • negative bias for clear sky conditions in wintertime• In wintertime positive bias at pixels with fog
• Longwave radiation• Negative bias for clear sky conditions in wintertime
