1-YEAR OBSERVATIONS OF MOUNT-PINATUBO AEROSOL WITH AN ADVANCED RAMAN LIDAR OVER GERMANY AT 53.5-DEGREES-N

A combined Raman elastic-backscatter lidar is utilized to observe the development of the stratospheric perturbation after the strong eruptions of Mount Pinatubo in June 1991. Height profiles of the particle extinction and backscatter coefficients are determined simultaneously and independently of each other. From these data the area-weighted mean particle radius and the aerosol surface area and mass are determined. The lidar measurements are taken at Geesthacht in northern Germany (53.5-degrees-N, 10.5-degrees-E). The Pinatubo aerosol layer is located between the tropopause and about 24 km height. Traces of stratospheric aerosol were frequently found down to 5 km height. The optical depth of the stratospheric aerosol layer has been of the order of 0.15 in 1992. The ratio of optical depth to column-integrated backscatter varied between about 15 and 60 sr. Most values were found between 20 and 30 sr. Extinction-to-backscatter ratios > 50, between 20 and 30, and < 15 sr indicate effective particle radii < 0.2, between 0.2 and 0.75, and > 0.75 mum, respectively, as Mie scattering calculations show. Variations of the extinction-to-backscatter ratio with height between about 10 and 90 sr were observed. Column aerosol mass and surface area were of the order of 0.05 g m-2 and 2.5 x 10(11) mum2 m-2 in the first half of 1992.