近幾年來，氣候變遷、全球暖化的議題已逐漸受到人們重視，IPCC 報告中提到自上個世紀以來，全球大氣溫度因為二氧化碳濃度增加而有明顯的暖化趨勢。大氣溫度上升除了引起各地區的溫度場產生變化，大尺度的氣象環流場也因此有所改變。而由於汙染物與氣象環境的關係密切，大氣環境改變勢必也將影響人類居住環境的空氣品質。因此本篇研究選定了 1979-1983(A5)及 2006-2010(B5)，過去和現在的各五年，並選定汙染物濃度高值的十月份進行 WRF 氣象模式及 CMAQ 空氣品質模式的模擬。以了解在氣候變遷的環境下，台灣氣象場及汙染物濃度分布的變化特性。同時為了解過去三十年東亞大尺度氣象環流場的改變，本研究亦討論了NCEP-NCAR Reanalysis 2 再分析資料，分析結果發現：(1)1000 hPa 溫度大約上升 1-1.5 度 (2)副熱帶高壓勢力增強同時東退速度減緩，(3)台灣附近海域出現明顯低壓擾動趨勢，而東北季風的伴隨則加速了台灣鄰近區域的風場分布。從 WRF 的降尺度模擬中發現，台灣東南方海域出現的低壓擾動趨勢，加速了台灣地區的東北季風場，並為台灣帶來較多的雨量，進而造成土壤溼度增加而地表溫度降低，使白天熱力作用減弱導致邊界層高度降低。而晚上則因為東北季風增強導致垂直風切增大，提升了夜間邊界層高度的發展。另外，在區域環流的分析中，本研究也發現白天海風減弱與夜晚陸風增強的情形。在污染物濃度部分，受到增強的東北季風影響，北部地區的汙染物濃度明顯下降，而中南部地區則因白天海風減弱使得汙染物不易擴散，而累積在沿海汙染源區附近。另外，夜間邊界層高度上升減緩了晚上地表附近的汙染物濃度，但北部地區的臭氧濃度卻有增加的情形。 To understand the impact of climate changes on meteorological conditions and its subsequent effect on air quality in Taiwan from the past 30 years, WRF model and CMAQ air quality simulations were performed. Two episodes that represents past (year 1979-1983) and current (year 2006-2010) conditions were selected and were named A5 and B5 respectively. In this study, simulations were only performed for month October. The analysis of NCEP NCAR Reanalysis 2 for the past 30-years exhibits the following patterns. First, the air temperature increases in a magnitude of 1-1.5 degree Celsius. Second, the westward stretching of subtropical high pressure system is closer to Taiwan in B5 period. Third, there is a decreasing tendency of sea surface pressure and enhanced northeasterly monsoonal flow in area of Taiwan. The increased air and sea surface temperature enhances the evaporation processes. In addition, the atmosphere is susceptible to instability that induces more precipitation in B5 period and enhances the soil moisture content. With this condition, the skin temperature is reduced that suppress the development of the daytime PBL height. At night, the strengthened wind shear around Taiwan enhances the boundary layer development. In general, in northern Taiwan, the enhanced northeasterly wind reduce air pollution. With weaker sea breeze flow in B5 period, emission sources are prone to accumulate near the source region. The PBL height also moderately affects the air pollutants concentrations.
