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Recent SINERGEE results and future plans Richard Allan and Tony Slingo Environmental Systems Science Centre, Univ

Met Office, Exeter, October 27 th 2004. Recent SINERGEE results and future plans Richard Allan and Tony Slingo Environmental Systems Science Centre, University of Reading Sean Milton, Ian Culverwell and Malcolm Brooks Met Office. Overview. 1) Recent comparisons 2) SINERGEE paper:

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Recent SINERGEE results and future plans Richard Allan and Tony Slingo Environmental Systems Science Centre, Univ

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  1. Met Office, Exeter, October 27th 2004 Recent SINERGEE results and future plans Richard Allan and Tony Slingo Environmental Systems Science Centre, University of Reading Sean Milton, Ian Culverwell and Malcolm Brooks Met Office

  2. Overview • 1) Recent comparisons • 2) SINERGEE paper: • Methodology and first comparisons • Clear-sky fluxes over the ocean • 3) Future plans

  3. OLR ALBEDO Recent Comparison Monday 25th October 2004 1200 UTC http://www.nerc-essc.ac.uk/~rpa/GERB/gerb.html

  4. 30th April 2004: “GERB-view” Model OLR and RSW are interpolated onto the GERB grid

  5. Examples of model and GERB grid (a) Sub-satellite (b) mid-latitude

  6. OLR albedo MODEL GERB CERES DJF 2003/4

  7. DATA ISSUES & VALIDATION • Current data are preliminary and are being validated • Data Issues: • geolocation, • radiance to flux processing • Missing/bad data • Spectral response/calibration • Recent data (2004) use SEVIRI for radiance to flux processing, have improved geolocation and reduced missing data compared to earlier data

  8. 3) Validation: Clear-sky Irradiance Over the Ocean • Compare GERB and the Model where the model fluxes are likely to be most accurate • e.g. Clear-sky OLR over the ocean • Perform comparisons where both GERB/SEVIRI and the model find clear-skies • Consistent sampling • Perform radiative calculations using model verification statistics as input to Edwards-Slingo radiative transfer model to gauge likely error in model fluxes

  9. Input profiles to radiation scheme

  10. Radiative Computations • Model minus radiosonde profile OLR • -3 to +5 Wm-2 mean difference • Model plus obs-model RMS T error • ~ +3 Wm-2 • Model plus obs-model RMS RH error • -5 to –9 Wm-2 • Albedo sensitivity to • Climatological aerosol: 0.001 to 0.01 • Surface albedo increase of 0.005: 0.003

  11. Results:Model Errors of orderOLRc ~ 5-10 Wm-2 (~3%) albedoc ~ 0.01 (~15%)

  12. Scatter plot of GERB clear-sky values versus model May to August 2003: MS7A processing OLR Albedo

  13. Scatter plot of GERB clear-sky values versus model December 2003 to February 2004: SEVIRI processing OLR Albedo

  14. Clear-sky OLR over open ocean (June 2004)

  15. Clear-sky albedo over open ocean (June 2004)

  16. Time series: Mediterranean (clear-sky, open ocean) OLR Albedo

  17. Time series: Mediterranean (clear-sky, open ocean) OLR Albedo

  18. Previously identified model errors • 1) Sahara: surface albedo and desert dust • 2) marine startocumulus • 3) convection over tropical Africa • 4) convection over ITCZ and cirrus outflow Some details in EUMETSAT proceedings paper: Allan et al. (2004), SINERGEE: simulation and exploitation of data from Meteosat-8 using an NWP model,EUMETSAT Meteorological Satellites Conference, Prague, Czech Republic, p. 122-130.

  19. Clear-sky sampled OLR and Albedo Left:MJJA 2003 Right:DJF 2003/04

  20. Namibian Stratocumulus region31st March 2004

  21. Errors in the representation of tropical convection in the model GERB/NCEP MODEL

  22. Occasional large differences in OLR seem to be due to excess cloud in the ITCZ OLR for 1200z 1 July 2003 (shading) Contours show vertical motion (solid=ascent, dashed=descent) GERB Model

  23. CONCLUSIONS • DATA VALIDATION • data quality improving (geolocation, radiance to flux conversion, …) • clear-sky OLR and albedo over the ocean • MODEL EVALUATION • Previously identified model errors: • Convection over land • Cirrus outflow/ convection over ocean • Albedo and aerosol over the Sahara • Stratocumulus • FUTURE ANALYSIS • Extend analysis of model errors • Extended forecast runs (e.g. model time-step output for afew days) • Experimental runs (new cloud scheme, new albedo, etc) • SEVIRI…

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