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GOME-202-2 slit function analysis PM2 Part 2: Changes – theta_d_0 & SFS shape R. Siddans, B. Latter, B. Kerridge RAL Remote Sensing Group 26 th June 2012 RAL. GOME-2 FM202-2: PM2 Slit function analysis. Overview of slit-function fitting method New results for FM202-2 (WP2100)
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GOME-202-2 slit function analysisPM2Part 2: Changes – theta_d_0 & SFS shapeR. Siddans, B. Latter, B. KerridgeRAL Remote Sensing Group26th June 2012RAL
GOME-2 FM202-2: PM2Slit function analysis • Overview of slit-function fitting method • New results for FM202-2 (WP2100) • - use of new angular parameters from TNO • - modification of source line shape to match commissioning measurements • Comparisons of results: • - FM202-2 to FM202-1 • - FM202-2 1mm to FM202-2 0.5mm • Error analysis for FM202-2 • Discussion re next steps, date of next meeting (FP) • AVHRR/GOME-2 co-location, spatial aliasing and geo-referencing (Ruediger Lang)
Measurement setup: • 2004: FM202-1 Echelle angles • 1.0mm: 73.6-78.376 • 0.5mm: 76.0 – 77.188 • 2012: FM202-2 Echelle angles (same) • 1.0mm: 73.6 - 78.376 • 0.5mm: 76.0 – 77.284
SFS predicted wavelengths • After PM1, TNO provided updated theta_d_0 & scaling factors (per dataset) • Their fitting method meant problems with FPA1 due to low signal (dataset 6 bad) • For theta_d_0, FPA3&4 used. For scaling_factor, FPA 2-4 used Dataset 6 v1 v2
TNP theta_d_0 & scaling_factor Error from FPA1 weak signal
2004 SFS line shape Modelled Measured(2004) 254nm Modelled Measured(2004) 543nm 297nm 633nm 300nm 1mm slit only
2012 SFS line shape change Modelled (2004) Measured (2012) 543nm 1mm 633nm 1mm 633nm 0.5mm Modelled (2012) Measured (2012) 543nm 1mm 633nm 1mm 633nm 0.5mm 543nm 1mm 633nm 1mm
Laser measurements: Gaussian broadening • “The line shape of the SFS lines is influenced by the internal alignment of the stimulus. For the FM2-2 measurements the SFS was taken out of storage and realigned. The alignment was not perfect, resulting in a more Gaussian line shape.” • Bad measurment file: • [2010-12-13]_[18_04_34]_FM2_SLITFUN-05EXP-000062-EXP_77.295998.avgfile • SFS changes: • Ghosts - Same grating, but didn’t match FM203. Ref. Angle? • From SFS commissioning report, neighbouring peak seems to modify slit peak wavelength as well as shape and wings?
FM202-2 Initial retrievals and test (PM1): FM202_2_0_5 FPA2 (band 2) pix 304-328
FM202-2 Updated parameters (PM2): FM202_2_0_5 FPA2 (band 2) pix 304-328
FM202-2 Updated parameters (PM), Gauss SFS: FM202_2_0_5 FPA2 (band 2) pix 304-328