An Eulerian model for a slowly moving cold frontal system with sulfur chemistry: Model description and application

Simple sulfur chemistry is incorporated with a diagnostic cloud module to furnish an Eulerian model for slowly moving cold frontal systems. Chemical species include sulfur dioxide and sulfate in air, cloud and rain water. The diagnostic method to determine cloud water content is rather crude at present, but the primary results, including a three-dimensionmal test, seem reasonable. Two-dimensional applications of the model are made for a precipitation event presented in a frontal process in March 1988, Guagdong Province, southern China. The cross-section is selected to be representative of major industrial areas of Guangdong. The analysis of the modeling results displays the effects of the lifting and shearing of the wind field onto the distribution patterns of pollutant distributions. Clouds are shown widely polluted with the lifting and entrainment of the polluted air from lower layers, so that acid rain was generated in the precipitation area following the front, covering the most part of Guangdong Province. The pllutants are transported northerly with the front surface are generally transported southerly, but in-cloud pollutants are transported northerly with a wider extension. The results qualitatively show that the transport of acidic precursors in such a weather system is of medium scale and the acidic deposition in Guangdong might be contributed mainly by the sources of Guangdong Province itself.