ON NUMERICAL-SIMULATION OF THE GLOBAL DISTRIBUTION OF SULFATE AEROSOLPRODUCED BY A LARGE VOLCANIC-ERUPTION

Volcanic eruptions play an important role in the global sulfur cycle o f the earth's atmosphere and have a relatively big influence on potent ial 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 dis tribution of sulfate aerosol produced by the oxidation of SO2 released to the atmosphere. The theoretical considerations are illustrated usi ng the case of the recent volcanic eruption of Mt. Pinatubo, which occ urred in June of 1991. The methodology of the study is based on the ap plication of a dynamic global model of the atmosphere coupled with a s ystem of mass conservation equations for atmospheric trace species. Th e chemistry of SO2 oxidation in dry and wet phases and emission held a re represented by the right-hand sides of the tracer equations. The cl ouds in our calculations are represented by the cloud cover, the cloud liquid water field, the precipitation field, and a flag indicating th e 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 extens ively following the Mt. Pinatubo eruption. The verification shows that the numerical model presented accurately simulates the global distrib ution of sulfates. In the conclusions of the paper, the authors presen t other applications of the proposed methodology in the area of atmosp heric chemistry.