Surface Layer Transport of Sulfate Particles in the Western United States by the Large-Scale Wind Field

Abstract

The transport patterns of fine sulfur aerosols in the western United States are shown. The large-scale resultant horizontal flux was computed in terms of that contributed by the mean flux versus that contributed by a turbulence, or eddy, component. The large-scale eddy component of the resultant flux is shown to be important in many cases. In the northern Great Plains the eddy flux often has a greater magnitude than the mean flux and its direction is from the east, opposite the mean flux. In the southwestern United States, the transport is accomplished primarily by the mean flow and the direction is from the south. This indicates that high sulfur concentrations are carried into the northern Great Plains from the east as periodic episodes, while high concentrations in the south are caused by sources to the south which are within the mean flow field.