IMPACT OF INSTRUMENTAL DEGRADATION AND SOLAR CYCLE EFFECTS ON LONG-TERM VARIATIONS OF NLC PARTICLE SIZE RETRIEVALS WITH SCIAMACHY/ENVISAT

摘要

SCIAMACHY limb-scatter measurements allow the continuous mapping of noctilucent clouds (NLCs) as well as the retrieval of NLC particle sizes since 2002. Long-term measurements of NLC particle sizes require high instrument stability or an accurate knowledge of the changing calibration parameters. For the NLC measurements we employ measurements in SCIAMACHY channel 1, whose transmission decreased significantly and non-linearly with time. This contribution describes the effect of instrumental degradation - if not properly corrected for - on the retrieved NLC particle sizes. Furthermore, a degradation correction scheme as well as a correction for solar cycle changes in the solar spectrum are described.