POLAR STRATOSPHERIC CLOUDS AS DEDUCED FROM MLS AND CLAES MEASUREMENTS

From 30 August 1992 to 3 September 1992 supersaturated area at 465 K p otential temperature (similar to 50 hPa) is deduced from MLS water vap our measurements over western Antarctica, where high extinction coeffi cients measured by CLAES indicate Polar Stratospheric Clouds (PSCs). T hese PSCs are attributed partly to the effect of an anticyclone locate d over South America and partly to localized orographic waves, which r aise the isentropes and generate rapid adiabatic cooling. A local mini mum in column O-3 (less than or equal to 200 DU) is observed in this a rea, which is believed to be a consequence of the dynamics. Enhanced C lO abundances downstream of the region indicate PSC processing and chl orine activation.