Level 1.5 Processing Issues Martin Bates RAL Level 1.5 Processing Issues • Geolocation – – – – Current Status TSOL Jitter (CSOL-TSOL) correction Longterm TSOL Jitter Solution Comparisons with RGP Processing • Upcoming Updates to Processing • Processing Validation Current Status • Level 1.5: Adhoc E-W geolocation correction – sinusoid (amplitude, phase, offset tunable) – ESU dependent – accurate to ~1 pixel, a bit worse NS. • Level 2: fit to SEVIRI data (formerly MS7A) – decoupled from Level 1.5 – accurate to ~ 0.2 pixels (< 0.5 pixels) 09 Nov 2003 TSOL Jitter • Predicted TSOL – actual TSOL – as used by IMPF – predicted TSOL (CSOL) from rotational model • Temporary scheme – data available on ftp server at EUMETSAT since 16 February • coverage > 99.6 % (dropouts at sun-satellite colinearity) – copy across and use as correction to E-W geolocation – ggsps correction for early April. TSOL Jitter data spikey – needs filtering 14 Nov 2003 Smoothed TSOL Jitter Result of median filter ( 1 minute) One spike in close-up Corrected Data (15 Nov 2003) no filtering am/pm Systematic 15 Nov 2003 TSOL Jitter Correction 23 March 2004 TSOL Jitter Correction 23 March 2004 am/pm systematic still present 23 March 2004 offset slightly different Long term solution • Robustness of ftp server solution in question. • Longer term solution: – append (TSOL Jitter) value to GERB packet – correction algorithmically no different – improved reliability and timeliness of information • Timescale: 6-12 months. – requires Engineering Change Proposal (for IMPF and UMARF) – still to be approved by EUMETSAT • SEVIRI reprocessing ? – can then get values for before 16 Feb. RGP Comparisons • Process data from 14-16 Nov 2003 using TSOL jitter correction. • Compare to RGP geolocation (high CPU fit) comparing to SEVIRI. North-South Compression 15 Nov 2004 11:56:58 (SW) Still there ! N/S offset not perfect for these data Quasi-Rotation 15 Nov 2004 11:56:58 (SW) Also still there ... Retune Optical Model ? 1. Could be due to local deformations in one of the mirrors – but no estimate of possible sizes of effects 2. Image ratio plots more structure in GGSPS plot GGSPS RGP Geolocation Plans • Interim TSOL Jitter Correction (April) • Long term TSOL Jitter Correction – for improved robustness – still to be approved, end of year ? • Optical Model – tune using RMIB info • Axis misalignments – MSG spin to MSG structure • large (~0.3 ?) • changes at each manoeuvre – action on EUMETSAT to investigate • Mirror Side Effects (non-parallel N/S ?) Upcoming Processing Updates • New BAT, BBRAD tables – but may be coordinated with data release • Offline gains (stray light & moon avoidance) – depends on gain stability: • if update < once per month – use offline gains (data table) • if update more frequently – avoid problem regions or – use gains calculated at good times of day » startup problems & time dependent processing • Stray Light Correction TBD • Numerous minor updates – NCR fixes – additions (diagnostics) to NANRG product – confidence flag definitions Processing Validation • Geolocation Validation – Comparisons with SEVIRI / RGP geolocation (RMIB) • Overall Validation – series of unit and integration tests done (test data, limited set of circumstances) – step by step validation using real data and checkpoint files suggested (validation plan) – TBD – monitoring of calibration parameters using engineering report (Imperial).