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UP: Umweltphysik
UP 4: Atmosph
ärische Aerosole
UP 4.6: Fachvortrag
Monday, March 13, 2006, 17:45–18:00, E
Cloud retrieval using SCIAMACHY data: The Heidelberg Iterative Cloud Retrieval Utilities (HICRU) — •Michael Grzegorski, Ulrich Platt, and Thomas Wagner — Institute of environmental physics, University of Heidelberg, Im Neuenheimer Feld 229, 69118 Heidelberg
The SCanning Imaging Absorption spectrometer for Atmospheric ChartographY (SCIAMACHY) on ENVISAT-1 allows measurement of different tropospheric trace gases (e.g. NO2, SO2, CH4) using the DOAS technique. Cloud detection algorithms are essential for calculating the vertical column density. A widely used method determines cloud fraction using broad band spectrometers, the Polarization Monitoring Devices (PMDs). A precise calculation of thresholds representing cloud free and completely cloudy scenarios is essential for the computation of cloud fractions. Image sequence analysis is suited to determine the lower threshold, which depends on region and time. The upper threshold is independent from earth albedo, but have to be calculated with depend to different physical, geometrical and instrumental properties. The results of HICRU can be combined with DOAS evaluation of O2 and O4 to retrieve further cloud parameters. This presentation shows the design of the algorithm as well as results and intercomparisions with other cloud algorithms.