AN EULERIAN MODEL FOR A SLOWLY MOVING COLD FRONTAL SYSTEM WITH SULFURCHEMISTRY - 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-di mensional test, seem reasonable. Two-dimensional applications of the m odel are made for a precipitation event presented in a frontal process in March 1988, Guangdong Province, southern China. The cross-section is selected to be representative of major industrial areas of Guangdon g. The analysis of the modeling results displays the effects of the li fting and shearing of the wind field onto the distribution patterns of pollutant distributions. Clouds are shown widely polluted with the li fting and entrainment of the polluted air from lower layers, so that a cid rain was generated in the precipitation area following the front, covering the most part of Guangdong Province. The pollutants below the front surface are generally transported southerly, but in-cloud pollu tants are transported northerly with a wider extension. The results qu alitatively show that the transport of acidic precursors in such a wea ther system is of medium scale and the acidic deposition in Guangdong might be contributed mainly by the sources of Guangdong Province itsel f.