Evolution of the Pinatubo Volcanic Cloud Over Hampton, Virginia

Abstract

A series of eruptions of the Philippine Mt. Pinatubo volcano in June 1991 climaxed in cataclysmic eruptions on June 15-16, which greatly perturbed the stratospheric aerosol layer. These eruptions yielded an estimated 20 megatonnes of SO2, which is nearly three times the amount produced by the eruptions of El Chichon in 1982 (Bluth et al., 1991). Lidar measurements taken at 694 nm by the 48-inch lidar system at Langley Research Center (LaRC) in Hampton, Virginia, show the vertical distribution, intensity and spread of the Pinatubo aerosol layers over this mid-latitude location. The peak stratospheric aerosol burden, which occurred in late February 1992, is equivalent to an optical depth of approximately 0.2 at 694 nm. In the subsequent nine months, the stratospheric loading has decreased with an l/e decay rate of 7.3 months. The magnitudes, transport times, and decay rates of the volcanic aerosol layers following Pinatubo and El Chichon are compared.