水平傳送對大台北地區光化生成臭氧的影響研究

The Effect of Horizontal Transport on the Ozone Production in Taipei

柳中明(Chung-Ming Liu)

《大氣科學》 21卷1期 (1993/03) Pp. 1-22

摘要

本文延續柳（1992）的研究，採用數值模式，以分析水平風場傳送對台北地區近地面臭氧時空變化的影響。經詳細分析後，發現南北（Y軸）方向上風場傳送，主要影響各區污染物濃度之絕對值變化；而東西（X軸）方向上風場傳送，主要影響各污染物逐時變化特徵。將X、Y軸風場傳送均考慮後，本模式順利模擬出南區午時O3濃度最高，次為中區，最低在北區的實測現象。同時午時高臭氧濃度在離地約0.8 KM附近，亦與板橋臭氧剖面觀測相似，且午時臭氧為一日中最高濃度。日落後50公尺以上，因輻射冷卻逆溫層的出現，而致臭氧累積的情形，亦因水平風傳送而減緩，但仍維持50公尺以上臭氧濃度較高的現象。此高層臭氧可能在日出後，因為輻射冷卻逆溫層的被破壞，而向下傳送至近地面，加速近地面臭氧生成與累積。總結而言，本文所採用之模式，較之於複雜之三維模式，為非常簡易，但已能模擬出實測的各種現象，更且可用以分析垂直熱力紊流擴散、水平傳送、化學反應，日出前高層臭氧等，對近地面臭氧累積之影響。不過，仍無法用以分析海陸風環流所造成的垂直方向傳輸情形。

關鍵字

臭氧光化反應 ； 數值模式

並列摘要

This paper continues the study by Liu (1992) and applies a numerical model to study the effect of horizontal transport on the temporal and spatial distribution of surface ozone in Taipei. The results show that the airflow along the north-south direction (Y-axis) have a significant effect on the noontime maximum ozone level, whereas the airflow along the east-north direction (X-axis) have a direct effect on the temporal variation of ozone. After including the transport effect into our simplified model, we can simulate the observed phenomenon of a highest noontime ozone amount at southern Taipei region and a lowest concentration at northern region. Meanwhile, the peak ozone level along the vertical direction is at about 800m above the ground, which is quite similar to what have been observed by the Central Weather Bureau at Panchiao. After sunset, there is some accumulation of ozone above 50m height, just above the inversion layer formed b by the radiative cooling effect. The accumulated ozone can be transported downward to surface after sunrise when the nighttime inversion layer breaks, and then enhance the production of ozone. In short, the current model provides us an opportunity to analyze the effects of turbulence, transport, chemical reactions, and initial ozone profile on the surface ozone accumulation. However, it can not resolve the vertical structure formed by a pronounced land-sea breeze circulation.

並列關鍵字

ozone production and simulation