Lidar measurements of Mt. Pinatubo aerosols at Aberystwyth from August 1991 through March 1992

Abstract

Measurements of stratospheric aerosols were conducted at Aberystwyth (52.4°N, 4.0°W) from 14 August 1991 to 30 March 1992, using a dual‐polarisation lidar at 532 nm. The backscatter ratios show that volcanic aerosols, present below 22 km in August, built up steadily during the autumn and extended to higher altitudes. During 7–9 December a large increase in aerosol amounts was observed, with maximum backscatter ratios of 17 and aerosols reaching 34 km. Thereafter, peak backscatter ratios remained around 8, with aerosols extending up to 28 km. Optical depths increased tenfold during the period of measurements, from .02 in August to about 0.2 in March. A notable feature of the aerosol cloud was a layer of depolarising particles, first seen near 19 km on October 1st, which gradually subsided during the course of the autumn and winter.