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First results with SEVIRI in the RMIB GERB Processing

First results with SEVIRI in the RMIB GERB Processing. Nicolas Clerbaux and RMIB GERB team Royal Meteorological Institute of Belgium GIST 20 – Reading – 25,26,27 November 2003. Content. RMIB SEVIRI Reception Status, GERB unfiltering with SEVIRI, SEVIRI NB-to-BB conversion

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First results with SEVIRI in the RMIB GERB Processing

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  1. First results with SEVIRI in the RMIB GERB Processing Nicolas Clerbaux and RMIB GERB team Royal Meteorological Institute of Belgium GIST 20 – Reading – 25,26,27 November 2003

  2. Content • RMIB SEVIRI Reception Status, • GERB unfiltering with SEVIRI, • SEVIRI NB-to-BB conversion • SEVIRI scene identification, • GERB radiance-to-flux conversion • Planning for future works • Conclusions

  3. 1. RMIB SEVIRI Reception Status • Reception and archiving started at RMIB 29 July 2003, but with a lot of missing segments. Missing segments problem mostly solved 14 Nov. 2003. Still some dissemination problems and commissioning activities (documented by EUMETSAT). • Training of an operator (Patrick Vandermeulen) to manage the SEVIRI archive and to operate the SEVIRI processing. • “SEVIRI processing” running in parallel with (Meteosat-7 processing) since 20 October 2003. Under validation. • Image availability last 9 days [15 Nov:23 Nov] • Expected Images : 9 * 96 * 12 = 10 368 images • Not received: 57 (0.5%) • Received but with Missing segments : 97 (0.93%) • Slot availability last 9 days [15 Nov:23 Nov] • Expected slot: 9*96=864 • Incomplete slot : 6 (0.69%) • Slot with missing segments: 21 (2.43%) • Reception status: http://gerb.oma.be/seviri/Status/

  4. 2. GERB Unfiltering with SEVIRI - Method second order polynomial regressions Unfiltering factor from SEVIRI

  5. Shortwave Unfiltering SBDART Scatterplot

  6. Longwave Unfiltering SBDART Scatterplot

  7. Shortwave Unfiltering factor from SEVIRI : 299311181200 SBDART Scatterplot Scatterplot from SEVIRI

  8. Longwave Unfiltering factor from SEVIRI : 299311181200 SBDART Scatterplot Scatterplot from SEVIRI

  9. Comparison with Direct Unfiltering-SBDART Database- Shortwave Direct Unfiltering SBDART scatterplot • Standard Deviation (1-sigma) of the error is [%]: • 0.30% for Dir. Unfilt. • 0.21% with SEVIRI SEVIRI Unfiltering SBDART scatterplot

  10. Comparison with Direct Unfiltering-SBDART Database- Longwave Direct Unfiltering • Standard Deviation (1-sigma) of the error is [%]: • 0.11% for Dir. Unfilt. • 0.03% with SEVIRI SEVIRI Unfiltering

  11. Unfiltering Validation (ongoing) • Validation of the parameterization using a data base of spectral radiance curves at TOA built using MODTRAN 3.7 provided by the CERES team (Norman Loeb).

  12. std.dev. =0.69% std.dev. = 0.085% Direct -shortwave Direct -longwave std.dev. = 0.77% std.dev. = 0.07% SEVIRI -shortwave SEVIRI -longwave

  13. 3. SEVIRI NB-to-BB conversion • Needed for the unfiltering (cf. before) and for resolution enhancement • Validation: with GERB

  14. Ratio GERB measurement/SEVIRI estimation (without correction for the geolocation!) Results OK in shortwave and longwave, except over desert. Will be improved in the future.

  15. 4. SEVIRI Scene Identification • Needed for the shortwave ADMs selection (surface type, cloud fraction, optical depth t and phase). • Method: building of clear sky reflectance images for the SEVIRI VIS 0.6 and VIS 0.8mm (each 10 days) and analyse of the difference with actual NB reflectance. NIR 1.6 and IR for for cloud phase. • TBD: aerosol and wind speed over clear ocean, fresh snow detection.

  16. SEVIRI False Color Clear sky Reflectance Image R=rcs (0.8mm) G=rcs (0.8mm) B=rcs (0.6mm) Ref: A. Ipe et al., Pixel -Scale Composite TOA Clear-Sky Reflectances for Meteosat-7 Visible Data, Journal of Geophysical Research, in press.

  17. VIS 0.6 or VIS 0.8 ? Automatic selection of the more appropriated channel for cloud detection and cloud optical depth estimation: 0.6mm 0.8mm

  18. Cloud Optical DepthRetrieval Use of 24 look-up-tables: for: - VIS 0.6 and VIS 0.8 - 6 surface types - Ice and water clouds with: -r = actual reflectance -rcs = clear sky refl. -(qv,qs,j)=viewing geom.

  19. Shortwave Angular Dependency Models Use of the 592 CERES-TRMM SW ADMs:

  20. Longwave Angular Dependency Models with Ref: N. Clerbaux et al., Outgoing longwave flux estimation: improvement of angular modelling using spectral information, Rem. Sens.,2003, 85, 369-395.

  21. Future work and planning • Switch to SEVIRI as imager input in the RGP: Dec. 2003. • Finalisation of the SEVIRI unfiltering for end of 2003 (optimisation, validation, update of the documentation). • First half of 2003: validation/optimisation of the radiance-to-flux conversions.

  22. Conclusions • SEVIRI data looks fine (incl. calibration), • Archiving procedure OK, • Processing OK (comp. time about 4’/slot), • SEVIRI unfiltering implemented and tested using SBDART data base. Ongoing validation with MODTRAN. • Other parts of the processing look OK.

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