EPA-92-FA11-03-A217

092

1,400 千元

2003/09/22

2004/07/30

國立成功大學吳義林副

空保處

財團法人成大研究發展基金會

化學物質管理

無線電探空定向儀,繫留氣球,高空臭氧偵測器,自由基平衡計算,混合層,,,,

radiosonde,tethersonde,ozonesonde,radical budget

賴進興教授、林清和副教授

邱慧真

06-2386764

niki67@ms2.url.com.tw

本計畫針對高高屏地區空氣污染問題，在地表處利用環保署自動監測站之監測數據與其他氣態污染物(甲醛、HNO3與H2O2)之採樣及氣象條件(溫度、濕度、日照強度與NO2之光解速率常數(J-NO2))之觀測；在高空中利用釋放氣球(radiosonde)、繫留氣球(tethersonde、ozonesonde及採樣袋)與輕航機(GPS與O3 monitor)採樣，藉以了解高高屏地區空氣污染在三度空間中垂直與水平之分佈現象。 從監測站資料中發現，在採樣期間(民國92年10/25~11/1與93年5/12~5/15)發現，高高屏地區在這十二天中之指標污染物幾乎均為臭氧，且在10/28、10/30、10/31與11/1均有數個測站之臭氧最大小時濃度超過120 ppb，所以將這四天稱為臭氧事件日。從氣象條件中發現，溫度與J-NO2之值在出現臭氧事件日之四天中比其他四天高，且radiosonde之結果顯示，發生事件日的四天中，混合層明顯較低。 在繫留氣球採樣中發現，高高屏濱海地區存在著海陸風交替之現象，早上十點前盛行東北風，十點後至傍晚均以西北風為主。而在ozonesonde之採樣結果中發現，大氣之垂直與水平傳輸作用對臭氧濃度之分佈具有一定的影響力，且常在混合層之上發現較高濃度之殘留臭氧，在事件日發生當天晚上與隔日清晨更為明顯，甚至高達100 ppb。從採樣袋之結果中發現 ，高空中有時會有高污染煙流經過，其中高濃度之NO常對臭氧產生消耗的作用(NO titration effect)。 本計畫中輕航機採樣共分三條路線：(A)美濃興達線；(B)美濃林邊線；(C)高屏溪內陸線；(D)美濃林園線，飛行時間均在早上六點至七點半之間，針對臭氧濃度進行三度空間的分析。結果顯示，可能由於地形與風向之雙重作用，造成臭氧濃度在美濃地區較高，但在混合層上方卻未見較高濃度之殘留臭氧，且在航線B中發現，臭氧濃度在高高屏地區有西高東低之現象存在。 應用radical budget預測臭氧生成速率明顯較實測值高出許多，原因應為模式預測之過氧自由基濃度偏高，若能進行過氧自由基之實測修正後，應可得到較符合實際值之結果。此外，傳輸作用對臭氧生成速率之貢獻，在早上10點前應主要為垂直傳輸之作用，地表臭氧濃度之變化量約9.88~117.72％，但此計算方法僅為粗估，其中實應包含光化學反應之貢獻，若能夠藉由模式預測由光化學反應生成之臭氧貢獻量，將可更進一步準確的推估混和層上臭氧對地表之貢獻量。

無線電探空定向儀,繫留氣球,高空臭氧偵測器,自由基平衡計算,混合層,,,,

0000014127.pdf

3MB

[期末報告]公開版

2005/2/1 上午 12:00:00

Ozonesonde, tethered balloon and instrumented ultralight aircraft were used to measure the spatial and temporal variations of air pollutant concentrations. In addition, the photolysis rate of NO2, the concentrations of HNO3 and H2O2 were measured to evaluate the effects of photochemical reactions. The field campaigns were conducted during October 25th to November 1st, 2003 and May 12th to 15th, 2004 in southern Taiwan. There were several monitoring sites with ozone concentrations exceeding 120 ppb on October 28th, 30th, 31st, and November 1st during the field campaigns and they were called the event days. In the event days, the ambient temperature and photolysis rate of NO2 were greater and daily maximum mixing heights were smaller. Sea-land breeze was significant in the October campaign: dominant northeastern wind before 10 am and prevailing northwestern wind during daytime within the surface layer. Due to the effects of dry deposition and NO titration from mobile sources, the surface ozone concentrations decreased to less than 20 ppb after 8 pm. However, the ozone concentrations might be greater than 100 ppb at higher elevation due to the effect of temperature inversion at night and the ozone residence layer persisted until the following morning. The ozone residence layer from the previous day contributed to the surface ozone concentrations in the following morning by 9.9 to 118% due to vertical transport. The radical budget method overestimated the ozone production rates due to the overestimation of HO2 radical concentrations. Therefore, the HO2 radical concentrations should be measured in the future study to evaluate the contributions from various processes. Both HNO3 and H2O2 concentrations showed significant diurnal variations with maximum concentrations at the early afternoon. The ozone sensitivity analyses based on the HNO3 and H2O2 concentrations showed that control measures for both NOx and NMHC were needed to reduce the ozone concentrations.

radiosonde,tethersonde,ozonesonde,radical budget