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CM-SAF TOA radiation status report

D. Caprion Royal Meteorological Institute of Belgium. CM-SAF TOA radiation status report. Overview. CERES status GERB status and reprocessing TOA flux products status Missing data (sunglint...) New chains. CERES status. Use of CERES ES9 products Available until June 2006

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CM-SAF TOA radiation status report

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  1. D. Caprion Royal Meteorological Institute of Belgium CM-SAF TOA radiation status report

  2. Overview • CERES status • GERB status and reprocessing • TOA flux products status • Missing data (sunglint...) • New chains

  3. CERES status • Use of CERES ES9 products • Available until June 2006 • No plan to switch to CERES SRBAVG products • No suitable for “real time” usage • Maybe to be include in a future reprocessing

  4. GERB status • 2 instruments on fly (GERB 2 /SEVIRI 1 and GERB 1 / SEVIRI 2): • Data from both satellites are consistent • Currently GERB 2 operational • But stopped at night (between 20:00 and 02:00) till mid-October: eclipse season • When SEVIRI 2 operational then switch to GERB 1

  5. GERB reprocessing • Two steps (at the RMIB) • First compute clearsky • Then compute fluxes for any month • Technical restrictions • Take a few weeks (2 or 3) for the clearsky (from 02/2004 to 03/2006) • 1 month of data in 2 weeks (worse case) for the fluxes (same period) • But… depends on pre-processing at the RAL (quite fast) • Schedule • Should start this week • First some « independent » dates to cover validation and intercalibration studies • Later all since February 2004

  6. TOA products status • Most of the production chains stopped 04/2006 • STA products (fluxes at SEVIRI resolution needed for surface fluxes) are still produced • So what did we do ? • GERB/GERB_like intercalibration • Change of the production chains • Introduction of GERB aerosol products

  7. GERB/GERB_like intercalibration • Why ? • need to solve the “sunglint” and “edge” problems

  8. GERB/GERB_like intercalibration • Impact on treatment: e.g. sunglint effect ! Monthly Mean April 2006 Reflected Solar Flux

  9. GERB/GERB_like intercalibration • Impact on treatment: • Missing data strategy has to be changed: i.e. replacement of GERB-like by GERB • Until now: image per image. • From now on: pixel per pixel ! Get intro trouble: inter-calibration !

  10. GERB/GERB_like inter-calibration • Idea: GERB and GERB-like (mean) fluxes are proportional <Fgerb_like>= k * <Fgerb> • Strong assumption : • k is constant over a month • then it can be determined from monthly mean flux

  11. GERB/GERB_like intercalibration

  12. GERB/GERB_like inter-calibration • Second idea: (only for shortwave) • First correct the diurnal cycle effect (i.e. flatten the curve) • Rescale FGerb_like to FGerb FGerb_like=k*(a(qs,qv,...)*FGerb) • Correction to take into account: • solar angle qs • viewing angle qv • and more if needed… like surface type for instance

  13. GERB/GERB_like intercalibration • Introduction of 9 matrices of correction: • 3 surfaces types (ocean – vegetation – desert) • 3 types of sky (clear – partially cloudy – cloudy) • The coefficients of theses matrices depend on solar zenithal angle (sza) and viewing zenithal angle (vza) • Sza and Vza are binned every 10° between 0° and 90° • The matrices were computed with a set of random data picked up in March and April 2006

  14. GERB/GERB-like intercalibration • So what we get is something like (9 times): # CLEAR OCEAN 1.115 1.111 1.092 1.077 1.068 1.074 1.089 1.089 1.091 1.080 1.068 1.073 1.072 1.070 1.085 1.093 1.057 1.050 1.056 1.071 1.079 1.073 1.083 1.090 1.031 1.045 1.051 1.067 1.080 1.076 1.087 1.090 1.017 1.039 1.052 1.062 1.078 1.077 1.086 1.095 1.008 1.031 1.047 1.064 1.078 1.083 1.090 1.097 1.002 1.025 1.045 1.069 1.086 1.086 1.103 1.108 1.005 1.032 1.054 1.074 1.088 1.084 1.089 1.083 NOT REALLY UNDERSTANDABLE

  15. GERB/GERB_like intercalibration a = factor to scale the GERB_like to GERB

  16. GERB/GERB_like intercalibration a = factor to scale the GERB_like to GERB

  17. GERB/GERB_like intercalibration a = factor to scale the GERB_like to GERB

  18. GERB/GERB_like intercalibration

  19. GERB/GERB_like intercalibration Percentage of GERB_like Monthly Mean April 2006 Reflected Solar Flux (GERB + GERB_like)

  20. New production chains • Before: First mapping onto sinusoidal grid then averaging • Now: First averaging and then mapping to LonLat grid and sinusoidal grid • So : We had to (re)write and/or update part of the softwares

  21. Gerb aerosol products • New products: aerosol optical depth compute with VIS-0.6, VIS-0.8 and IR-1.6 + dust detection Daily mean of aod 0.8 SEVIRI grid 27th April 2006

  22. Gerb aerosol products • With both projection: Sinusoidal grid LatLon grid

  23. In the next weeks/months • Restart of the production chains • Check of the corrections on « winter » months • Update of the cmsaf.oma.be web site • New status page corresponding to the new chains • Pages software sources (with username and password)

  24. Last but not least • User feedback: (need surface albedo) • Why 15km2 resolution when SAF Land has a SEVIRI resolution ? • Why such a limited area ? • Why surface albedo only over land ? • The command and the retrieval of the data are not clear • Interface not intuitive • Problem with the ftp through a browser • But quite fast !!!!

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