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Rob Roebeling, A. Feijt, E. Wolters

Rob Roebeling, A. Feijt, E. Wolters. BBC2 Workshop 18 – 19 October 2004, De Bilt, The Netherlands COMPARISON OF METEOSAT-8 AND NOAA-17 BASED CLOUD MICROPHYSICAL PROPERTIES. Introduction. Climate Monitoring SAF Method to retrieve Cloud Physical Properties

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Rob Roebeling, A. Feijt, E. Wolters

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  1. Rob Roebeling, A. Feijt, E. Wolters BBC2 Workshop 18 – 19 October 2004, De Bilt, The Netherlands COMPARISON OF METEOSAT-8 AND NOAA-17 BASED CLOUD MICROPHYSICAL PROPERTIES

  2. Introduction • Climate Monitoring SAF • Method to retrieve Cloud Physical Properties • Comparison NOAA-17 and Meteosat-8 • Validation activities • Conclusions

  3. The CM-SAF

  4. CM-SAF Climate Monitoring Satellite Application Facility (CM-SAF) Objective To generate and archive high quality data products fromMSG, AVHRR and METOP satellites on a continuous basis, which are relevant for climate research. Involvement KNMI • Research and development Cloud Physical Product retrievals. • Validation Cloud Physical Products with in-situ data of dedicated cloud measurement campaigns. Co-sponsoring: European Meteorological Satellite Organization (EUMETSAT) Project team : DWD (coordinator), FMI, KNMI, RMIB, SMHI and Meteo Swiss

  5. Cloud Thermodynamic Phase Cloud Liquid Water Path Cloud Optical Thickness 13 August 2001, 12:25 UTC. CM-SAF: Cloud Physical Products

  6. Methods

  7. q0 q f Methods: Radiative Transfer Modelling Reflectance,  tac Above the cloud • Phase • Optical Thickness • GeometricThickness • Droplet Density • Effective Radius Scattering and absorption tbc Below the cloud R(sur)

  8. Retrieval Method Water Clouds Ice Clouds

  9. Calibration

  10. Calibration Comparisons NOAA-17 and Meteosat-8 reflectances • Calibration NOAA-17 with pre-launch calibration coefficients(NOAA-17 post-launch calibration coefficients not available) • Calibration Meteosat-8 with pre-launch calibration coefficients (Meteosat-8 calibration shows small drift (Govaerts, 2004)) Note: Bi-directional effects were not considered

  11. Calibration NOAA-17 1.6 micron, 28 March 2004 10:09 UTC Meteosat-8 1.6 micron, 28 March 2004 10:00 UTC

  12. Calibration: AVHRR and MSG Refectances Scatterplot 0.6 micron channel Scatterplot 1.6 micron channel

  13. Comparison CPP products

  14. Comparison: Cloud Physical Products Comparison of CM-SAF Cloud Physical Products from Meteosat-8 and NOAA-17/AVHRR • For the period April - 15 May 2004 instantaneous NOAA and Meteosat-8 products were compared to assess: • The accuracy of Meteosat-8 retrievals • The possibility to derive time series Meteosat-8 cloud properties for Cabauw

  15. Comparison: Cloud Optical Depth Meteosat 8, 19 April 2004 10:00 NOAA-17, 19 April 2004 10:08

  16. Comparison: AVHRR and MSG COT and CLWP 19 April 2004 10:00 19 April 2004 10:00

  17. Validation with BBC2 and CLOUD-NET data

  18. Cabauw Chilbolton Paris Validation: Preparation Data Set Time series of cloud properties from BBC2 and Cloud-Net lidar/radar and microwave radiometer data to obtain: • Cloud Top Temperature • Cloud Top Height • Cloud Phase • Cloud Liquid Water Path • Cloud Optical Thickness

  19. Validation: Example CLWP Fig. Cabauw, all cases Fig. Cabauw, > 50% water clouds

  20. Instantaneous average CLWP Meteosat-8 (10:00 utc) = 15 g.m-2 Noaa-17 (10:08 utc) = 22 g.m-2 AVHRR Overpass Daily CLWP Meteosat-8 Average = 73 g.m-2 Std = 78 g.m-2 Validation: Time series CLWP Meteosat-8 Cabauw, 19 April 2004

  21. Conclusions

  22. Conclusions • Meteosat-8 and NOAA 0.6 micron reflectance are similar. • Meteosat-8 and NOAA 1.6 micron reflectance differ 30% • Meteosat-8 COT and CLWP retrievals look realistic. • Correlations Meteosat-8 and NOAA derived COT and CLWP is reasonable (r_cor  0.75)

  23. Conclusions • Meteosat-8 retrievals are more sensitive to errors, especially for thick, semi-transparent and broken cloud fields • Meteosat-8 for BBC2 are needed to validate time series of cloud property retrievals (CLWP, COT and Reff)

  24. Thank you !

  25. Validation Continuous validation studies are needed to monitor the product quality • Validation sites are essential for the CM-SAF • Sites with a regular spatial distribution • Data collection on a continuous basis • Validation sites in other climate regions are needed. Preferably, an ARM sites concept should be adopted in Europe and Africa.

  26. CalibrationRTM simulations water clouds DAK simulation 28 March 2004 10:00 NOAA-17 geometry DAK simulation 28 March 2004 10:00 Meteosat-8 geometry

  27. Comparison: Cloud Liquid Water Path Meteosat 8, 19 April 2004 10:00 NOAA-17, 19 April 2004 10:08

  28. Instantaneous average CLWP Meteosat-8 (10:00 utc) = 15 g.m-2 Noaa-17 (10:08 utc) = 22 g.m-2 Daily CLWP Meteosat-8 Average = 73 g.m-2 Std = 78 g.m-2 Validation: Time series COT and CLWP Meteosat-8 Cabauw, 19 April 2004 AVHRR Overpass

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