本研究旨在探討東亞地區硫沉降之時空分佈特性，吾人應用與修改HYSPLIT模式，以2001年為基準，模擬東亞地區SO2與SO42-之排放、擴散、傳送、轉換及沉降，以及境外污染排放對於台灣本島硫沉降量的貢獻程度。 結果顯示東亞地區 (95°E-145°E ,10°N-40°N) 硫溼沉降量佔總硫沉降量的58.2%，較硫乾沉降來得多。大陸性質的區域 (中國與南韓) 硫乾沉降量佔總沉降量的比例較硫溼沉降量大；島嶼性質的區域 (日本與台灣) 則相反。硫乾沉降量模擬結果的數值分布受排放位置的影響很大，高值的位置不會隨著季節交替而明顯變動。整體來看硫乾沉降量的趨勢與雨量趨勢明顯相反。硫溼沉降量模擬結果的數值分布受到降水與排放兩者同時影響，在數值上會因為季節改變而有明顯的消長。整體來看硫溼沉降量與雨量具明顯的正相關性。 HYSPLIT模擬值與觀測值比較的結果顯示，台灣北部地區模擬結果較為接近觀測值，於南部則在五月到九月期間有明顯的低估情況。硫溼沉降明顯的受到境外硫排放移入的影響，且所佔比例與季節變化之間有明顯的關連，而硫乾沉降則正好相反。此外在不同的氣候條件所造成的降水型態，境外移入比例也將呈現不同的特徵，基本上東北季風型降水所造成之境外移入比例最高，其次為秋冬鋒面型降水。 The purpose of this study is to investigate the emission, dispersion, transport and deposition of sulfur compounds in East Asia for the year of 2001 using the HYSPLIT (Hybrid Single-Practice Lagrangian Integrated Trajectory) model. The contribution of sulfur deposition via long range to Taiwan was also assessed. Model results show that wet deposition pathway contributed about 58.2% of the total sulfur deposition in East Asia (95°E-145°E, 10°N-40°N). Sulfur dry deposition is higher than wet deposition in East Asian continent, and vice versa for island areas. Model results indicate that sulfur dry deposition was significantly correlated with source region. The location of maximum dry deposition remained at the same area regardless of seasonal change. The trend of sulfur dry deposition was opposite to that of precipitation. Sulfur wet deposition was influenced by precipitation and emission and it had a positive correlation with the former. The comparison between the simulation and observation of sulfur deposition indicated that both were close for the northern Taiwan but the former was much lower than the latter for the southern Taiwan in the months of May-September. Sulfur wet deposition in Taiwan was strongly affected through the long-range transport, depending on various weather conditions. Under the type of northeast monsoon, the contribution via the long-range transport to wet deposition was the largest and followed by the type of fall/winter frontal precipitation.
