Seasonal source: Receptor relationships in Asia

Abstract Seasonal source-receptor relationships are estimated for countries in Asia and the Indian sub-continent and the impact of long-range transport on countries’ deposition are explored through these relationships. The influence of precipitation patterns and changes in flow fields on deposition in southeast Asia and the Indian sub-continent is also demonstrated. Many of the small sulfur emitting countries in the region are found to receive more sulfur deposition than they emit, with the majority of their deposition coming from neighboring or even distant countries. For example, Vietnam accounts for 35% of its own deposition while Thailand contributes 19% and China 39%. Similarly, over 60% of the sulfur deposited on Nepal is due to Indian emissions. China’s contribution to Japan’s deposition is shown to exhibit strong seasonal dependence, with winter and spring contributions 2.5 times higher than summer and autumn. China and South Korea are found to play a major role in the deposition in southern and western Japan while volcanoes and domestic sources dominate in the north and east. The impact of Chinese emissions on Japan’s deposition is found to be highly sensitive to wet removal rates.