Stratospheric sulfate aerosol: A microphysical model

ulfate aerosol plays many important roles in the chemical and radiative budgets of the stratosphere. The predominant source of sulfate is large volcanic eruptions. However, an ambient layer of aerosol is observed even in volcanically quiescent periods, the sources of which are not quantitatively known. The regions and causes of new particle production are also not understood. In particular, an anomalous layer of small particles of uncertain origin is observed near 30 km in polar regions each spring. The vertical extent of stratospheric aerosol is also uncertain, limiting our knowledge of the impact of heterogeneous chemistry.;In order to address these questions of stratospheric aerosol theory, I have developed a numerical model of sulfate aerosol microphysics. I have incorporated this model into the Garcia-Solomon two-dimensional model of atmospheric dynamics and chemistry. Model calculations show carbonyl sulfide to be a very minor source of stratospheric aerosol, while tropospheric SO;The model shows that the observed layer of new particles near 30 km in polar spring results from rapid oxidation of SO;Heterogeneous reaction of...