OMI Measurements of Sulfur Dioxide Abundances and Altitudes of the Volcanic Plumes from Eruptions of Okmok and Kasatochi in 2008

Sulfur dioxide (SO2) injected into the atmosphere during volcanic eruptions is soon converted into sulfate aerosols, which promote ozone depletion and affect Earth's radiation balance and climate. The impact of an eruption depends on the amount of sulfate aerosols it produces, their spatial distribution and lifetime in the atmosphere. The sulfate aerosol amount is determined by the amount of SO2 emission, while the spread and lifetime largely depend on the injection altitude. In this presentation, we describe a newly developed retrieval method, named the Iterative Spectral Fitting (ISF) algorithm, for simultaneous quantification of the SO2 column amount and estimation of plume altitude from satellite backscattered ultraviolet (buv) measurements. The ISF algorithm is applied to buv measurements from the Dutch-Finish Ozone Monitoring Instrument (OMI) on NASA Aura satellite. The results for the 2008 eruptions of Okmok and Kasatochi on Aleutian Island (Alaska) are presented and compared with the operational OMI products. We demonstrate that significant improvements in the determination of SO2 abundances of these volcanic plumes are achieved using the ISF technique, and show for the first time that SO2 plume altitudes are directly estimated from space borne buv measurements.