level 1.5 processing issues martin bates ral. level 1.5 processing issues geolocation –current...
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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
TSOL Jitter Correction
23 March 2004
TSOL Jitter Correction
23 March 2004
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 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).