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COSMO General Meeting 2007 WG5 Parallel Session 18 September 2007

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.

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COSMO General Meeting 2007 WG5 Parallel Session 18 September 2007

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  1. 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. 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. 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 Verification data Monthly mean SIS-DEM, December 2004 [B. Dürr]

  4. Radiation validation: Alpine Surface Radiation Budget (ASRB) network ASRB network consists of 10 sites (status October 2006)

  5. ASRB station Gornergrat, 3110 m asl Photo: Rolf Philipona, MeteoSwiss

  6. July 2006 Global radiation: daily averages (sun elevation > 5°) Comparison with MSG and ASRB Mean error -Verification with MSG Red crosses: clear sky gridpoints & pixels Error bars: stdev errors no bias for clear sky conditions in Summer, but clouds too less opaque (clouds too transparent)

  7. Cloudiness verification with SYNOPSummer 2006 : bias for +63..+72h Pirmin Kaufmann, MeteoSwiss

  8. Cloudiness verification with ANETZSummer 2006 : mean diurnal cycle Mean diurnal cycle bias / std dev / rms

  9. December 2006 Global radiation: daily averages (sun elevation > 5°) Comparison with MSG and ASRB Mean error -Verification with MSG Red crosses: clear sky gridpoints & pixels Error bars: stdev errors negative bias for clear sky conditions in Wintertime

  10. December 2006: only pixels with fog Global radiation: daily averages (sun elevation > 5°) Mean error -Verification with MSG positive bias at pixels with fog

  11. 24.12.2006 12 UTC MODIS

  12. global radiation: hourly values April 06 – March 07for clear sky conditions in COSMO-7 & ANETZ Vanessa Stauch, MeteoSwiss

  13. downward longwave radiation: Payerne @ 23 UTCclear-sky cases 1999-2001: COSMO-7 and MODTRAN vs ASRB 84 clear-sky nights 54 cases Dürr et.al., 2005: Meteorol. Z., 14, 47-55

  14. Downward longwave radiation: five COSMO-2 runs Winter 06/07 with subgrid topographic corrections with topographic corrections without topographic corrections Mean error - Verification with ASRB

  15. 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

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