Laser radar observations in mid-Wales of aerosols from the El Chichón eruption

Abstract

Observations using a laser radar system at Aberystwyth (52°25′n, 4°4′w) have shown enhanced concentrations of aerosols at heights up to ∼30 km. It is believed that these enhancements have been caused by eruptions of El Chichón (17°33′ n, 93°20′ w) in southern Mexico during the period 28 March to 4 April 1982. Data collected during 45 nights in the period November 1982 to February 1983 have shown the presence of such enhancements consistently since observations started on 6 November and represent the most northern excursion of the stratospheric cloud by that date^1,2. The results indicate a very pronounced variability in the cloud, both on a night-to-night basis and within given nights, the peak value for the ratio of backscatter from aerosols to that from molecules varying between 2 and 12. In these changes the aerosols can serve as a tracer of transport processes at stratospheric heights³.