2-DIMENSIONAL STRATOSPHERIC AEROSOL DISTRIBUTIONS DURING EASOE

LIDAR data of stratospheric aerosol layers from the Mount Pinatubo eru ption, taken on long range flights with a Transall aircraft, have been investigated to study the exchange of air-masses across the polar vor tex boundary. From these measurements we found that the center region of the stratospheric polar vortex was free of volcanic aerosol above P T values of 485 K throughout the whole winter, with the exception of s mall isolated clouds appearing at the end of Jan. 92. Below 420 K the aerosol layers are very homogeneous on an isentropic surface and do no t show much correlation with the vortex.