台灣位居東亞出流下風位置，當東北季風盛行，容易將東亞其他國家的空氣污染物傳輸到台灣本島，造成台灣本地的空氣污染。台灣地表空氣品質被影響之程度與時間長短，與本地污染疊合之現象，實為值得探討與瞭解之議題。本計畫科學目標架構於7-SEAS (Seven South East Asian Studies)研究計畫下，探討不同區域污染物(包含亞洲沙塵、生質燃燒、中國霧霾等)對於台灣空氣品質的影響。將以台灣北部之環保署光化學測站(photochemical assessment measurement system; PAMS)都會站進行PM2.5事件日境內外污染源之氣膠與揮發性有機物(volatile organic compounds; VOCs)成分與濃度比值作為輔助判定指標，建立一空品觀測預報系統，嘗試使用全球即時氣膠遙測與地面觀測搭配軌跡模式判定境外氣膠是否進入本島。當境外污染物進入到台灣後，藉由三維風場資訊，可以解析境外污染物傳輸高度，以及是否會隨下沉氣流混合至邊界層內，影響台灣地表的PM2.5空氣品質；同時藉由本實驗室所開發之全面二維層析質譜(comprehensive gas chromatography mass spectrometry; GCxGC-MS)與環保署PAMS光化學測站網VOC數據分析，採集空氣氣態樣品並分析PM2.5之氣膠與揮發性有機物組成，以瞭解當台灣發生PM2.5事件日時，境內外污染源如何鑑別；再由全球氣膠再分析場、區域空品化學傳輸模式與軌跡模式等共同解析境內外台灣氣膠污染來源、化學組成與境外輸入通量，以及該污染物對台灣空氣品質的影響等課題。因此以衛星遙測與大氣軌跡模式預報方法再結合大氣分析化學成分鑑定將能有效鑑別境內與境外空污霾害事件，並予之量化疊合個別貢獻。 ;During the northeasterly monsoon seasons, air pollutants from the Asian continent can be transported in long distance to elevate the baseline levels of air pollutants on the island and, when coupled with Taiwan’s indigenous emissions, may induce the occurrence of pollution episodes in Taiwan. As a result, it is intriguing to characterize the coupling phenomenon in terms of the occurrence and individual contributions. The research is a subproject of the integrated project 7-SEAS (Seven South East Asian Studies), which is to understand the evolutions of regional air pollutions (i.e., Asian dust, biomass burning and Chinese haze, etc.) and their air quality impact on Taiwan. In this research, we propose to use the time-series data of volatile organic compounds (VOCs) from EPA’s photochemical assessment monitoring stations (PAMS) either in absolute concentrations or ratios as indicators of long-range transport (LRT) in support of an aerosol air quality forecast system proposed herein. The forecast system uses NOAA real-time aerosol satellite retrievals together with trajectories to identify whether a distant polluted air mass will move into Taiwan; and whether that polluted air mass aloft will subside to the boundary layer and elevate the surface PM2.5 level based on the 3-D wind field. Simultaneously, we intend to use our newly developed atmospheric analytical method of comprehensive two-dimensional gas chromatography mass spectrometry (GCxGC-MS) together with EPA PAMS observations to find chemical markers that are able to differentiate LRT from indigenous episodes of PM2.5. The NASA aerosol reanalysis, regional chemical transport models and trajectory modeling all together can analyze the sources of origin, chemical composition, fluxes and their air-quality impact. As a result, the proposed approach of combining satellite observations with trajectory modeling as a forecast system to be further supported by innovated chemical analysis is expected to forge an effective means of differentiating and even quantifying the contributions of indigenous vs. LRT episodic PM2.5.
