RELATIONSHIPS BETWEEN OPTICAL EXTINCTION, BACKSCATTER AND AEROSOL SURFACE AND VOLUME IN THE STRATOSPHERE FOLLOWING THE ERUPTION OF MT-PINATUBO

The eruption of the Mt. Pinatubo volcano in the Philippines in June 19 91 has resulted in increases in the surface and mass concentrations of aerosol particles in the lower stratosphere. Airborne measurements ma de at midlatitudes between 15 and 21 km from August 1991 to March 1992 show that, prior to December 1991, the Pinatubo aerosol cloud varied widely in microphysical properties such as size distribution, number, surface and volume concentrations and was also spatially variable. Aer osol surface area concentration was found to be highly correlated to e xtinction at visible and near-infrared wavelengths throughout the meas urement period. Similarly, backscatter at common lidar wavelengths was a good predictor of aerosol volume concentrations. These results supp ort the use of satellite extinction measurements to estimate aerosol s urface and of lidar measurements to estimate aerosol volume or mass if temporal changes in the relationships between the variables are consi dered.