1 st post launch SCIAMACHY calibration & Verification Meeting L1b Astrium Friedrichshafen – Germany 24 July 2002 First level 1b Sun mean reference (SMR) analysis

Content Related Verification Tasks What has been looked at so far Orbit and State specifics First results Conclusions

Related Verification Tasks L : Range checking of various SMR record parameters L : Comparison of SMRs from different sources L : Comparison of in-flight and on-ground diffuser patterns L : Radiance sensitivity parameters unchanged

What has been looked at so far (1) L : Range checking of various SMR record parameters Wavelength of the sun spectrum Mean sun reference spectrum Relative radiometric precision of SMR Relative radiometric accuracy of SMR Diffuser/small aperture etalon Average mirror positions/elevation angles Mean value of the corresponding PMD values PMD out of band signal Doppler shift

What has been looked at so far (2) L : Radiance sensitivity parameters unchanged To calculate the absolutely calibrated solar reference spectrum, a number of on-ground derived key-data is needed When comparing the calculated SMR (as from 1b processor) against a literature Value, this tells us indirectly whether we have to expect changes in some of our Key-data.

Orbit and state specifics States: State ID 62 (ESM diffuser) Orbits 798, 814, 1597 For orbits 798 and 814 pre-defined state parameters have been commanded, which may lead to problems in the interpretation of absolutely calibrated spectra, because the diffuser is partly obstructed by the stiffening/mounting ring. For orbits 1597 so called beta-flight state configuration was commanded, explicitly avoiding obstruction of the diffuser

First Results (1) Can all this deviation be explained by the obstruction? Have some key-parameters changed? Other explanations?

First Results (2) Good agreement in channels 1,2 and 5 Factor of 2 in channels 3,4 and 6 Huge deviations in channel 7 and 8 Time - Normalisation problem (1b processor) THIS IS ICE

First Results (3) Good agreement in channels 1 to 6 – although it is not yet perfect. We first have to apply better in-flight calibration (Leakage, wavelength). Channels 7 and 8 are just bad due to ice problem.

Conclusions Fixing of in-flight auxiliary files for leakage current and spectral calibration Looking at the remaining 1b SMR ADS record fields (first of all still based on state 62) Comparison of different sources of SMR Derivation of “diffuser patterns” and comparison of on-ground ones Repair of time-normalisation problem in 1b processor