Berlin 2005 – wissenschaftliches Programm

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UP: Umweltphysik

UP 2: Aerosole II

UP 2.3: Fachvortrag

Montag, 7. März 2005, 17:00–17:15, TU HFT101

Determination of cloud parameters from SCIAMACHY for the correction of tropospheric trace gases — •Michael Grzegorski, Christian Frankenberg, Ulrich Platt, and Thomas Wagner — Institute of environmental physics, university of Heidelberg, Im Neuenheimer Feld 229, 69120 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 new algorithm developed for SCIAMACHY is based on the experience with the Heidelberg Iterative Cloud Retrieval Utilities (HICRU) designed for GOME, which is already well validated. The algorithm can also apply new instruments on SCIAMACHY, especially spectrometer in IR-wavelength-bands.