Mode radius and asymmetry factor of Mt. Pinatubo volcanic aerosols from balloon-borne optical measurements over Hyderabad during October 1991

Abstract

Using Sun-tracking photometers onboard balloon, the Pinatubo volcanic aerosol layer has been studied over Hyderabad (17.5°N) in October 1991, about 4 months after the eruption. From the aerosol extinction coefficients the mode radius and from the angular distribution of the scattered radiation intensity measurements the asymmetry factor g are determined. Mode radii are found to be in the range of 0.22±0.05 µm within the aerosol layer while g values are found to be 0.83±0.04, indicating the presence of larger particles. The mass determination reveals that the mass of the Pinatubo layer is about 0.053 gm^-2 which is 3.75 times higher than the earlier reported value for El Chichon layer, about 4 months after the eruptions.