Three lidar systems at the northern hemisphere sites of Naha and Tsukuba both in Japan, and Garmisch-Partenkirchen, Germany, have been observing the evolution, spread and decay of the aerosol cloud which have formed in the stratosphere after the explosive eruption of the Philippine volcano Pinatubo in mid-June 1991. Three years of lidar measurements show the depletion of the initial equatorial aerosol reservior and the subsequent transport to the north. These lidar data are the basis for the calculation of the climatically relevant parameters aerosol optical depth, mass and surface area. ¿ American Geophysical Union 1995