Detection of polar stratospheric clouds with ERS2/GOME data
- DLR, Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere
Polar Stratospheric Clouds (PSCs) are a phenomenon of both Arctic and Antarctic regions and form as a consequence of dramatic stratospheric cooling during the polar winter in altitudes between about 15 km and 25 km. Three main types of PSCs are generally defined, a common type 1 consisting of nitric acid trihydrate particles, a rarer type 2 consisting of ice particles, and a type 3 occurring in relation to mountain lee waves. The formation process of PSCs is accompanied by dehydration and denitrification of the stratosphere that influence the ozone chemistry thus leading to the development of the ozone hole. Therefore, identification of PSC events with data from satellites will be very important for monitoring the regions of potential ozone depletion. Based on radiative transfer calculations it is studied whether Polar Stratospheric Clouds (PSCs) can be detected by the new Global Ozone Monitoring Experiment (GOME) onboard the second European Research Satellite (ERS-2) planned to be launched in winter 1994/95. It is proposed to identify PSC covered areas by use of an indicator, the Normalized Radiance Difference (NRD), which relates the different of two spectral radiances at 0.515 {micro}m and 0.76 {micro}m to one radiance measured in the center of the oxygen A-based at 0.76 {micro}m. In presence of PSCs and under conditions of increasing solar zenith angles above {Theta} = 80{degree} the NRD rapidly decrease to values clearly below those derived under conditions of a cloud free stratosphere. Calculations for {Theta} = 86{degree} show that the method is successful independent from existing tropospheric clouds and by different tropospheric aerosol loadings or surface albedos. For solar zenith angles {Theta} < 80{degree} the PSC detection needs additional information about tropospheric clouds.
- OSTI ID:
- 220671
- Report Number(s):
- CONF-9409265--; ISBN 0-8194-1641-X
- Country of Publication:
- United States
- Language:
- English
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