Long‐range transport of SO<i>_x</i> and dust in East Asia during the PEM B Experiment

Abstract

The transport of SO 2 and sulfate in East Asia (including eastern China, Korea, and Japan) during the period of March 1 through March 14, 1994, is studied using a three‐dimensional regional‐scale atmospheric chemistry model. This period corresponds to that in which the Pacific Exploratory Mission in the Western Pacific Ocean (PEM‐West B) was being conducted around Japan. During this period, characterized by the passage of cold fronts and relatively dry conditions, the anthropogenic sulfur emitted from the source regions in East Asia is transported out into the central Pacific Ocean. The sulfur transport is largely limited to the lower 4 km of the atmosphere, with the maximum flux occurring in the 30° to 40°N latitude band containing the bulk of the anthropogenic emissions. The interactions between the sulfur cycle and mineral aerosol are also included in the analysis. It is found that the chemical conversion of SO 2 to sulfate in the presence of mineral aerosol may be a significant process during this time period, and may contribute from 20% to 40% of the total sulfate production. Sulfur dioxide arising from volcanic sources in Japan is also discussed.