First results on the retrieval of noctilucent cloud albedo and occurrence rate from SCIAMACHY/Envisat satellite nadir measurements

We present the first results on the retrieval of noctilucent cloud (NLC) albedos and occurrence rates from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartography) nadir data. The applicability of already available algorithms is discussed and necessary changes are reasoned. The occurrence rates for different latitude ranges are presented. During the summer period, when NLCs occur, the NLC occurrence rates show a maximum which is strongest at the highest latitudes. This is consistent with other observation methods. For the spring and autumn period, however, false NLC detections are observed at latitudes between 45°N and 65°N, where no NLCs are expected. The reason for this, and why it does not affect the retrieval during the NLC season is discussed. We also compared the SCIAMACHY nadir NLC occurrence rates with the ones retrieved from the SCIAMACHY limb measurements and the ones of SBUV and found qualitative agreement of these data sets.