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UP: Fachverband Umweltphysik

UP 12: Methods - Remote Sensing

UP 12.2: Vortrag

Donnerstag, 10. März 2016, 11:30–11:45, H41

Detection of noctilucent clouds in SCIAMACHY/Envisat nadir UV-measurements — •Langowski Martin and Christian von Savigny — Ernst-Moritz-Arndt-Universität Greifswald, Greifswald, Deutschland

The polar summer mesopause is the coldest region in the Earth's atmosphere and yields favorable conditions for cloud formation during three summer months and >50 deg. latitude. These clouds are called noctilucent clouds (NLC), as through their high altitude of about 83 km they are still illuminated several hours after/before sunset/sunrise. As NLCs were first observed in 1885, it is discussed if they are an indicator for climate change. Some long term studies show a long term trend, while others do not. An issue in this analysis is that long term studies rely on satellites with drifting local time. Currently a new algorithm for the GOME, SCIAMACHY and GOME-2 instruments is being developed to extend the NLC data from nadir measurements. This algorithm is an adaption of the algorithm used in other long term studies to the specifications of the three instruments. The algorithm searches for strong positive deviations in the albedo of different nadir measurements, which are caused by a higher reflection of solar radiation by the NLCs. The instruments are very similar and have a similar local time (9:30, 10:00 and 10:30) at the descending node during their whole measurement period. We aim to retrieve NLC albedo, occurrence rate and ice water content for all three instruments which until now combine 20 years of nadir data. This data set will then by analyzed for long term trends.