Airborne lidar observation of mountain-wave-induced polar stratospheric clouds during EASOE

The airborne backscatter lidar Leandre was flown during the EASOE campaign on board the French ARAT-Fokker 27, to provide mesoscale observations of scattering layers in the stratosphere. The use of cross-polarization channels at the 532 nm laser emitted wavelength, allowed discrimination between the quasi-spherical particles of the Pinatubo aerosol and the non-spherical frozen particles of polar stratospheric clouds. Measurements taken on December 11th 1991 revealed mountain-wave-induced polar stratospheric clouds at 21 km altitude, extending over 300 km west and 300 km east from Kiruna. The wavelength and amplitude of the perturbation imply local cooling ranging from 3°K to 10°K in the stratosphere, taking the temperature below the threshold of formation of polar stratospheric clouds.