Retrieval of the Pinatubo-aerosol optical depth and microphysical parameters from lidar measurements

Three techniques are reviewed which are presently applied to retrieve optical and microphysical parameters of the stratospheric aerosol from lidar backscatter signals. Measurement examples are presented to demonstrate the potential of the different methods and to document the stratospheric perturbation caused by the violent eruptions of Mount Pinatubo in June 1991. Lidar observations of the optical depth and microphysical properties such as the particle surface-area concentration are needed to support model calculations performed to quantify the influence of the volcanic aerosol on the global climate and the stratospheric ozone chemistry. The measurement examples show that the optical depth of the Pinatubo aerosol layer was of the order of 0. 1 during the first two years after the eruption. The surface-area concentration exceeded 10 mu m2 cm(-3) which is regarded to be a threshold for a significant depletion of ozone in the lower stratosphere during the winter seasons 1992 and 1993.