Sulfur deposition in Asia: Seasonal behavior and contributions from various energy sectors

Sulfur transport and deposition in Asia, on an annual and seasonal basis, i s analyzed using the ATMOS model. Calculations are performed for two comple te years (1990 and 1995). Deposition amounts in excess of 0.5 g S m(-2) yr( -1) are estimated for large regions in Asia, with values as high as 10 g S m(-2) yr(-1) in southeastern China. Annual averaged SO2 concentrations in e xcess of 20 mug SO2 m(-3) are calculated for many urban and suburban areas of eastern China and S. Korea, with an average of 5 mug SO2 m(-3) over most of the emitter regions. Sulfur deposition by major source categories is al so studied. Southeast Asia (Indonesia, Malaysia, Philippines, Singapore) re ceives similar to 25% of its sulfur deposition from shipping activities. Su lfur deposition from bio-fuel burning is significant for most of the underd eveloped regions in Asia. Volcanoes are a major source of sulfur emissions in the Pacific Ocean, Papua New Guinea, Philippines and Southern Japan. Sul fur deposition is shown to vary significantly throughout the year. The mons oons are found to be the largest factor controlling sulfur transport and de position in the Indian sub-continent and Southeast Asia. India receives ove r 35% of its total deposition during the summer months. In East Asia, sulfu r deposition is estimated to be 10% higher during summer and fall than wint er and spring. Model results are compared with observations from a number o f monitoring networks in Asia and are found to be generally consistent with the limited observations.