EVOLUTION OF THE INFRARED PROPERTIES OF THE MOUNT-PINATUBO AEROSOL CLOUD OVER LARAMIE, WYOMING

Particle size distributions measured from May 1991 to April 1994 over Laramie, Wyoming, are used in Mie calculations to model the wavelength dependence and the time evolution of the extinction, single-scatterin g albedo, and asymmetry parameters of stratospheric sulfate particles. The calculations cover the time period from 45 days before to 1080 da ys after the eruption of Mt. Pinatubo. The time evolution of the parti cle size distribution parameters and the evolution of the infrared ext inction are examined concurrently and interrelated in terms of the var iables present in the Mie equation for the extinction coefficient. The calculations are validated by comparing the theoretical model values to extinction measurements obtained by the Cryogenic Limb Array Etalon Spectrometer (CLAES), Improved Stratospheric and Mesospheric Sounder (ISAMS), Halogen Occultation Experiment (HALOE), and Stratospheric Aer osol and Gas Experiment (SAGE II) experiments. The Wyoming size distri butions are also used to derive simple mathematical expressions from w hich area and volume densities can be estimated using CLAES extinction measurements.