The eruptions of the Kasatochi volcano on 7 and 8 August 2008 led to an enhanced stratospheric aerosol load which was studied with the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL) at the French-German Arctic Research Base AWIPEV in Ny-Ålesund, Spitsbergen at 78.55°N, 11.56°E. During all KARL measurements from 15 August to 24 September 2008 (approximately 30 h of data), we detected distinct layers of enhanced aerosol backscatter in the lower stratosphere and the tropopause region, whose origination at the Kasatochi site can be shown by trajectory calculations. We found a 125% increase in aerosol optical depth compared to the mean values from 2004 to 2007 at 3 weeks after the eruption, validated by sunphotometer measurements. Differences in volume depolarization and color ratio signatures of the layers indicate a sinking movement of the bigger particles to the layer bottom. Furthermore, within higher stratospheric aerosol layers monitored after 25 August 2008, we observed the volume depolarization maximum to be up to 0.8 km below the backscatter maximum. Backscatter and depolarization measurements from 1 September 2008, on which data were collected over 13 h during daylight and darkness, are analyzed in detail. Calculations of the lidar ratio in the lowest aerosol layer as well as the estimation of microphysical parameters of the aerosol particles were performed.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic > WP 1.2: Aerosol, Water Vapour, and Ozone Feedbacks in the Arctic Climate System