On Numerical Simulation of the Global Distribution of Sulfate Aerosol Produced by a Large Volcanic Eruption

Abstract

Volcanic eruptions play an important role in the global sulfur cycle of the earth's atmosphere and have a relatively big influence on potential fluctuations of the atmospheric variables on both subclimatic and climatic scales. The objective of the present study is to establish a quantitative link between a major volcanic eruption and the global distribution of sulfate aerosol produced by the oxidation of SO2 released to the atmosphere. The theoretical considerations are illustrated using the case of the recent volcanic eruption of Mt. Pinatubo, which occurred in June of 1991. The methodology of the study is based on the application of a dynamic global model of the atmosphere coupled with a system of mass conservation equations for atmospheric trace species. The chemistry of SO2 oxidation in dry and wet phases and emission field are represented by the right-hand sides of the tracer equations. The clouds in our calculations are represented by the cloud cover, the cloud liquid water field, the precipitation field, and a flag indicating the type of clouds. The result of the simulation is the distribution of the sulfate aerosol on a global scale. The numerical model results are verified using the aerosol optical thickness that was measured extensively following the Mt. Pinatubo eruption. The verification shows that the numerical model presented accurately simulates the global distribution of sulfates. In the conclusions of the paper, the authors present other applications of the proposed methodology in the area of atmospheric chemistry.