2019-01-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/678051摘要：台灣中部地區過去十年空氣品質不良比率逐漸減少，但能見度並無等同之改善，導致民眾觀感不佳與環保團體質疑。從科學的觀點，空氣品質特別是細懸浮微粒(PM2.5)與能見度雖有關聯，但非直接的對等關係。有鑑於此，本計畫擬深究PM2.5來源與形成機制、微環境氣象及都市發展各項因子，探討與釐清前述反差現象之主要成因。研究方法結合固定與機動貨櫃測站的地面量測、太空衛星遙測與模式模擬，並建立地表氣膠物理與氣膠化學演算模式評估氣膠消光係數，再藉以同化衛星資料反演之消光係數與地景地貌時空變化，進而重建歷年消光係數之時空分布，探討土地利用及微環境氣象與能見度之關係；同時，透過高時間解析度氣膠物化特性量測，得以解析不同污染來源與化學組成對能見度之貢獻。 本兩年期計畫之研究目標，包括(1)探討空氣污染來源與細懸浮微粒(氣膠)成份變化的關係，(2)研究氣膠粒徑分佈、凝結核、吸濕成長及氣膠光學特性等物理參數在區域能見度(主要為消光係數)之影響，及(3)分析都市發展在地景地貌改變與空氣污染物生成及排放的關係，並研究短期氣候與天氣變化(如溫濕度、輻射通量、大氣邊界層變化等大氣因子)與氣膠物化特性、生成及傳輸擴散的關係等三大面向，期能提出廣泛且全面的視角重新審視台中地區之空污與能見度議題，並供後續控制策略與行動方案之制訂。 <br> Abstract: Air quality in Central Taiwan has improved grdually over the past decade, though the visibility has not changed much. This raises poor perception and great concerns from its citizens and NGOs. From a scientific view, visibility is related to air quality or more specifically the fine particulate matter (PM2.5), but not in a direct proportional relationship. With that in mind, this study proposes to evaluate the sources and formation mechanisms of PM2.5 to elucidate the likely causes to the aforementioned bottleneck in improving visibility. Data from ground-level measurements, satellite telemetry and mathematic models will be combined, while two independent methods: physical and chemical extinction efficiencies (bext) will be estimated based on the measured aerosol physicochemical properties. The estimated bext will then be used to assimilate the bext from satellite data, with which further being used to reconstruct the spatiotemporal distribution of past bext for evaluating the impact of land use and microenvironment meteorology on visibility. Meantime, the highly time-resolved aerosol physicochemical properties will be used for apportioning the contributions of sources and chemical-components on impaired visibility. This two-year proposal aims to (1) evaluate the relationships between air pollution sources and the chemical components of PM2.5, (2) characterize the roles of aerosol size distribution, cloud condensation nuclei, hygroscopic growth and optical properties in regional visibility, and (3) analyze the impacts of urban developments on land cover changes, formation and emission of air pollutants, and the relationships among short-term weather changes, aerosol physicochemical properties and regional transport. The outputs are expected to provide new insights and strong evidences critically needed to elucidate the causes of the un-coupling phenomena of improved PM pollution but degraded visibility. Furthermore, they will serve as the basis for effective control strategies for improving both PM pollution and visibility.都市發展空氣品質細懸浮微粒能見度消光係數氣候變遷urban developmentair qualityfine particulate mattervisibilitylight extinctionclimate change