ESA presentation

1
1st post launch SCIAMACHY calibration
Verification Meeting L1b Astrium Friedrichshafen
Germany 24 July 2002 First level 1b Sun mean
reference (SMR) analysis
2
Content
Related Verification Tasks
What has been looked at so far
Orbit and State specifics
First results
Conclusions
3
Related Verification Tasks
L1. 10.01 Range checking of various SMR record
parameters
L1. 10.02 Comparison of SMRs from different
sources
L1. 10.03 Comparison of in-flight and on-ground
diffuser patterns
L1. 02.03 Radiance sensitivity parameters
unchanged
4
What has been looked at so far (1)
L1. 10.01 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
5
What has been looked at so far (2)
L1. 02.03 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.
6
Orbit and state specifics
Orbits 798, 814, 1597
States State ID 62 (ESM diffuser)
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
7
First Results (1)
Can all this deviation be explained by the
obstruction? Have some key-parameters changed?
Other explanations?
8
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
9
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.
10
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