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 N- S. 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 14 Nov 2003 data spikey – needs filtering

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

am/pm Systematic 16 Nov 2003

TSOL Jitter Correction 23 March 2004

TSOL Jitter Correction 23 March 2004 am/pm systematic still present 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 Nov 2003 using TSOL jitter correction. Compare to RGP geolocation (high CPU fit) comparing to SEVIRI.

North-South Compression 15 Nov :56:58 (SW) Still there ! N/S offset not perfect for these data

Quasi-Rotation 15 Nov :56:58 (SW) Also still there...

Azimuth vs Column 15 Nov :56:58 (SW) Looks better...

TOTAL at night 15 Nov :12:47 (TOTAL) Azimuth vs pixelElevation vs pixel Similar results

SW in evening Azimuth vs Column Dark ! 15 Nov :58:57 (SW)

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 GGSPSRGP

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).