Two dimensional stratospheric aerosol distributions during EASOE

LIDAR data of stratospheric aerosol layers from the Mount Pinatubo eruption, taken on long range flights with a Transall aircraft, have been investigated to study the exchange of air‐masses across the polar vortex boundary. From these measurements we found that the center region of the stratospheric polar vortex was free of volcanic aerosol above PT values of 485 K throughout the whole winter, with the exception of small isolated clouds appearing at the end of Jan. 92. Below 420 K the aerosol layers are very homogeneous on an isentropic surface and do not show much correlation with the vortex.