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標題: | 臺灣地區臭氧濃度變化機制探討 The Mechanisms of Ozone Variation in Taiwan |
作者: | Cheng-En Yang 楊承恩 |
指導教授: | 陳正平 |
關鍵字: | 臭氧長期趨勢,本土外來比例,特性時間,滴定效應, ozone trend,local to long-range transport ratio,characteristic time,titration effect, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 本研究使用台灣空氣品質監測網污染物資料及中央氣象局臭氧探空資料分析1994-2003年台灣地區臭氧濃度長期變化之趨勢。綜觀各污染物濃度,只有臭氧在1994-2003年呈現逐年增加趨勢,平均每年濃度增加0.7±1.1 ppb。藉由本土外來比例估算台灣地區外圍環境傳送的臭氧濃度約為0.7±3.5 ppb。
分析質量保守方程得知污染物濃度與排放、混合層厚度、光化學機制、傳送與擴散機制有關,從中央氣象局板橋臭氧探空資料及台灣空氣品質監測網估算出臭氧的光化學特性時間約102-104秒,平流、垂直擴散及乾沉降的特性時間數量級則在104-106秒,顯示光化學機制對臭氧濃度影響較為快速。當NO濃度降低而風速較大時,臭氧濃度受平流機制影響可能增大,因此來自平流機制的貢獻也對臭氧濃度造成影響。 利用一維模式的模擬結果區分各項因子對臭氧濃度的影響,在NO/NO2的比例越大的的情況下,臭氧濃度受光化學機制影響較平流機制明顯,而NOX排放減量可造成臭氧濃度升高的結果。夜間主要影響臭氧濃度的機制則為平流過程,由於夜間背景濃度通常高於污染排放中心,臭氧濃度越接近污染排放中心將隨風速增加而上升。本研究推測1994-2003年台灣地區臭氧濃度增加主要原因是NOX排放的減量使滴定效應減弱,以及背景臭氧濃度增加而加強的平流效應。 This study applied observational data, theoretical anlysis and numerical model to analyze the trends of surface ozone in Taiwan. The measurement data showed an increasing trend of surface ozone concentration with a rate of 0.7±1.1ppb per year while other pollutants were decreasing from 1994 to 2003. A long-range transport analysis showed that background ozone has an increasing trend of 0.7±3.5 ppb per year. According to the mass balance equation, the change of pollutant concentration involves emission, mixing layer height, photochemical processes, and advection. The characteristic time of photochemistry of ozone is 102-104 seconds, and the characteristic time of advection, vertical diffusion, and dry deposition are about 104-106 seconds. Therefore, photochemistry affects the ozone level more rapidly than other factors. When NO concentration decreases and wind speed becomes stronger, advection could be an effective factor. Simulation results from a one-dimensional model showed that the results of ozone photochemistry are significantly influence under high NO/NO2 ratio, and a decrease in NOX emission, which gives lower local NO/NO2 ratio may enhance the ozone concentration due to a weaker titration effect. However, during the evening when there is no photochemical production, the major factor influencing ozone concentration is the advection process. So the local ozone concentration at the pollution center increases with increasing wind speed due to higher background ozone concentration. In summary, the increasing ozone trend in Taiwan was mainly due to reduce emission resulting in a weakened titration effect, as well as an increase in background ozone concentration that gives to stronger advection effect. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/31272 |
全文授權: | 有償授權 |
顯示於系所單位: | 大氣科學系 |
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