TEMPORAL DEVELOPMENT OF MT-PINATUBO AEROSOLS AS OBSERVED BY LIDAR ANDSUN PHOTOMETER AT NY-ALESUND, SPITSBERGEN

Since summer 1991 multiwavelength lidar and sun photometer observation s of the Pinatubo aerosol layer are performed at the Arctic NDSC stati on (Koldewey-Station) in Ny-Alesund, Spitsbergen. The height integrate d backscatter coefficient and the optical density decrease exponential ly in time with time constants of 0.89+/-0.39 and 0.94+/-0.37 years, r espectively. Their wavelength dependence indicates a decrease in media n particle radii between 1992 and 1993. It is shown that the observati ons are consistent with results of parameter-free model calculations. The calculations are based on the assumption that gravitational sedime ntation is the dominant process for volcanic aerosol removal in the Ar ctic stratosphere.