Evolution of the Mt. Pinatubo Volcanic Cloud and Analysis of Its Effect on the Ozone Amount as Observed from Ground-Based Measurements Performed in Northern and Southern Latitudes

Abstract

The decay of the Mt. Pinatubo volcanic cloud was monitored by systematic groundbased aerosol lidar systems implemented at the Observatoire de Haute-Provence (OHP, 44°N, 6°E) and at the Antarctic station of Dumont d’Urville (66.4°S, 140°E) Additional backscatter lidar measurements were also performed during the EASOE campaign in Sodankylä (67°N, 26°E). At northern mid-latitude, comparisons with the El Chichon volcanic cloud indicates similar aerosol loading but a longer residence time of the volcanic aerosols especially in the 15- 20 km altitude range. The analysis of the aerosol measurements obtained at the northern and southern polar latitudes shows that mixing can take place at the edge of the polar vortex in the lower stratosphere whereas the vortex remains mainly isolated above, especially in the southern hemisphere. The measurements performed in the winter and spring of 1992 in Dumont d’Urville allow to evaluate the subsidence of air inside the vortex, at a rate of 1 km/month at the 475 K potential temperature level. Besides, an ozone decrease of about 20 % as compared to the long-term climatology was recorded on the ozone sonde measurements performed at OHP in the 17 km to 22 km altitude range, in 1992 - 1993. The maximum depletion was found at the beginning of 1993, when it reached 30 % around 17 km, below the 2 sigma long term variability.