Bestimmung der Verteilung von Aerosol, polaren stratosphaerischen Wolken und Ozon in der arktischen Stratosphaere mittels eines flugzeuggetragenen Lidars

During the last years the distribution of aerosol, polar stratospheric clouds and ozone in the Arctic lower and middle stratosphere was probed for the first time during the whole winter with an airborne lidar. For this purpose a lidar system called OLEX has been developed at the institute of atmospheric physics of the German aerospace research establishment (DLR) in Oberpfaffenhofen. These measurements demonstrate that the stratospheric background aerosol is an excellent tracer to distinguish polar vortex air from air that originates from mid latitudes. The polar vortex showed up as a stable reaction vessel, whose edge was marked by a strong gradient in the aerosol concentration. After the Mt. Pinatubo eruption in 1991 the decay of the stratospheric aerosol density was monitored for four years. In the Arctic winter 1994/95 extended fields of polar stratospheric clouds were detected. Besides the three well known types of clouds a further type of cloud was found. In addition ice-clouds were measured by a lidar at 26 km altitude for the first time. These lee-wave induced clouds are not included in the standard climatologies of stratospheric clouds, but significantly alter the chlorine activation at these altitudes. In spring 1995 the ozone mixing ratio declined by about 50% throughout the polar vortex in a sharp defined altitude band. From the simultaneous detection of the stratospheric aerosol density dynamical reasons for this depletion can be excluded. This was the first time a photochemical ozone destruction comparable to the well known Antarctic ozone hole was detected in the northern hemisphere. (orig.)41 figs., 7 tabs., 96 refs.Available from TIB Hannover: RN 437(97-16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman