SCIAMACHY PMD Long Term Monitoring Results

The plots displayed on this page show results of the monitoring of SCIAMACHY's Polarisation Measurement Devices (PMDs).
Note that the monitoring data presented here have been reprocessed using actual (Level 1b V6.x upwards) radiometric key data.
Results are presented for the different SCIAMACHY light paths/viewing geometries:

• Nadir geometry (sun via the ESM mirror through the subsolar port and WLS via ESM mirror)
• Limb/occultation geometry (sun via ASM and ESM mirrors)
• Calibration light path (sun via ASM mirror and ESM diffuser)

Note that the subsolar data have been derived from pointing measurements which are performed less frequently than the fast sweep measurements which have been used for the science channels results.
All measured signals (in low gain) have been divided by the corresponding measurement at a reference time (currently 2 August 2002, at about orbit 2200), yielding an effective throughput for the different PMD light paths.
Measurements performed during times of reduced instrument performance (e.g. switch-offs or decontamination periods) have been omitted.
Since the PMDs are broadband devices, no spectral averaging is required.

The plots are updated on a daily basis, thus reflecting the current status of the instrument.

PMD 1 (Click to Enlarge)	PMD 2 (Click to Enlarge)
PMD 3 (Click to Enlarge)	PMD 4 (Click to Enlarge)
PMD 5 (Click to Enlarge)	PMD 6 (Click to Enlarge)
PMD 7 (Click to Enlarge)

Comments:

• General remark:
  The results presented here are based on the analysis of uncalibrated (Level 0) data, which have been corrected for dark current (constant value), (approximate) PMD scan angle dependency, and the seasonally varying distance to the Sun. Therefore variations smaller than about 1% require careful investigation.

• The timing of subsolar measurements before 30 November 2002 (about orbit 3922) did not consider the known yaw misalignment of SCIAMACHY on ENVISAT. The timing has been corrected in the final flight settings. Therefore, subsolar measurements from 2002 are not plotted, and all subsolar measurements have been referred to orbit 4519 (10 January 2003, just after a long decontamination phase).

• PMD 7 results are probably dominated by straylight and not reliable. They are only shown for completeness.
  
• WLS data are only available for PMD 1 to 3 because of saturation in the other PMD channels.

• PMD 4 seems to degrade much faster than the other PMDs (except for PMD 7, which covers the same spectral range). This issue is under investigation.

• The PMD 6 dark signal shows a strange variation which is currently under investigation.

• There are still some seasonal effects visible in the data which need to be corrected (especially for larger wavelengths).

Contact:

Stefan Noël (stefan.noel@iup.physik.uni-bremen.de)

©2009