Validation status overivew

1. Validation status overivew

2. V999 • Reprocessing of June-July 2004 and Dec 2004 with processing and calibration update carried out as a basis of a release • Provide a dataset for which we have CERES comparison campaign • Provide a non-moving target for comparison, can see the effect of changes on the same basic observations • Provide an usable volume of data for ‘instant’ release • Form the basis of a release document and can be used as for the assesment of accuracy and uncertainty • NOTE: further updates can be implemented on same test dataset

3. V999 calibration updates • Calibration updates • New spectral response due to ‘recovery’ of detector response • Improved internal black body calibration table • Spurious pixel to pixel variability removed • Updated ‘B’ factor using pixel-to-pixel variation obtained in-orbit from the calibration monitor • Running gains used and improved treatment of stray light

4. V999 processing updates • All level 2 updates implemented since the original processing and the reprocessing excersise these include: • The viewing angles corrected: the nominal position of the satellite is used in place of the rectification nominal value (0°). • Empirical correction for longwave radiance-to-flux conversion • Emperical correction for clearsky values in ocean sunglint region • Correction of rectification bug • New improved unfiltering lookup tables • In addition to recalculating for new spectral response, SW tables based on radiance not flux/, separate fit for ocean, separate fit for each angle. • LW table extended to 500m assuming black body curve • Improved geolocation • Originally planned to use an improved optical model and processing through with level 1.5 geo, in fact, level 1.5 geo improved, but level 2 processing performed with a significantly improved RGP geolocation derived by matching to SEVIRI • NB the level 2 geolocation of the quality of the reprocessing excersise is NOT OBTAINABLE IN REAL TIME without considerable expense of an unknown amount of further effort.

5. V999 observed changes • Geolocation significantly improved (both 1.5 and level 2) • Average SW radiance comparison with CERES shows GERB 6% higher, but reduced scene dependent difference • Longwave CERES-GERB comparisons show less good agreements (slight) due mainly to daytime comparisons, however more consistency between day-night comparison • Effect of empirical longwave flux correction seen as reduced angular variation in GERB-CERES flux comparisons. Signifcant changes to diurnal cycle for the Sahara • SW fluxes: clear problem in sunglint region and diurnal asymetry problem remains, minimal validation of shortwave fluxes

7. Requirements for release UPDATE USER DOCUMENTATION PROVIDE DATA QUALITY ASSESMENT DECIDE ON RELEASE STATERGY (what data when and how fast, with or without further improvements or differences to V999) FREEZE CLIMATE ARCHIVE PROCESSING (end to end) UNTIL RELEASE 2

8. Requirements for release • Use reprocessing dataset to provide uncertainty assessment • Any deviations from this need to decide if they are significant enough to demand a second reprocessing or else how to asses impact or decide not to implement • DO WE IMPLEMENT OTHER PLANNED IMPROVEMENTS, e.g. changes to SW fluxes, difference geolocation, altered cloud detection? • Geolocation accuracy of reprocessing not simple to obtain in NRT for release • Release to be made in ½ NRT with same geo system • Implement same system in NRT by paying 32,000€ • Find some other solution as accuracte, but how and how long? • Accept less accurate system, but must then reasses the accuracy of the products! • Spectral response • Use as tested ‘recovered’ response or consider witness sample (FM7) measurement – need to re-do comparison in latter case. • Decisions required on what we do about the flux issues • Provide without correction but detail of our current assesment?