臭氧（O3）在近地表中屬於衍生性空氣污染物，而地表的高臭氧濃度會對人類健康和生態系統造成不利的影響，其形成主要途徑為二氧化氮通過紫外線光解所產生，而由過去統計顯示在中午前臭氧濃度在短時間內有急遽上升之特徵，因此本研究的目的是統計2016及2019年全台各光化測站巨幅特徵臭氧頻率並探討其成因及參考比較國外文獻巨幅特徵之形成機制來了解台灣地區巨幅特徵臭氧形成與國外案例的差異。
本研究首先挑選出2016及2019年臭氧逐時濃度在2個小時內上升40 ppb以上之案例，並由巨幅特徵臭氧發生時間點，應用WRF氣象場資料模擬三維氣象場，並以HYSPLIT回推5小時的三維軌跡線，將上述軌跡線用於判別是否受同氣團之影響而導致測站之臭氧濃度上升，最後搭配Surfer推估軌跡線上巨幅特徵發生時段之臭氧逐時濃度，以比較逆軌跡上及測站該點臭氧濃度變化差異。此外，為了解析巨幅特徵之形成原因，分為化學反應中NOx及丙烯當量濃度與物理擴散共三種機制，並透過巨幅特徵事件日與同時段非事件日之濃度比值計算各機制之上升比例，以利後續量化各機制影響。
由2016及2019年巨幅特徵發生時段之站次數統計結果顯示與國外文獻一致，主要發生於下午1時之前，除了台西站外其餘光化測站皆以8~10時為最多巨幅特徵案例發生時段。由各月份站次數統計結果顯示除了北部空品區之光化測站外，其餘測站發生頻率最高主要為9~11月。
由2016及2019年同氣團影響之巨幅特徵案例之化學反應及物理擴散上升比例分別與觀測值加權平均臭氧上升比例之散點圖，結果顯示大部分案例為化學反應影響較大。此外，由各測站同氣團影響巨幅案例細分各案例物理擴散、NOx及丙烯當量濃度上升比例及其影響佔比，其中2016年，而2019年平鎮站案例皆以物理擴散影響較高為主；朴子、台南站、橋頭、林園及潮州站皆以NOx上升比例較高之案例數為主；而土城、忠明及台西站以丙烯當量濃度上升比例較高之案例數為主。因此綜合上述結果，並非所有2016及2019年台灣巨幅特徵事件日案例與國外文獻研究結果相同皆受高反應性VOCs影響而形成。

This study analyzes the event days of the rapid ozone concentration increase which are called non-typical ozone changes (NTOCs) in Taiwan and uses HYSPLIT-model to perform back-trajectory analyses in 2016 and 2019 to estimate the concentration variations within air parcel along trajectory. This study use back-trajectory during the NTOCs time to classify the ozone concentration increase at stations which is caused by the same air parcel. The statistical results show that the most of NTOCs cases occur during September and November, and occur before 1 p.m. in 2016 and 2019. To qualify the increase of ozone concentration, this study takes advantage of CO concentration to represent physical diffusion, propylene-equivalent concentration to represent VOCs influence and the photolysis of NO2 to represent NOx influence. The results indicate that the most of NTOCs cases are NOx influence in 2016, furthermore, the NTOCs cases of 3 stations are caused by VOCs influence and the NTOCs cases of 4 stations are caused by NOx influence in 2019.

1. Atkinson, R., & Arey, J., Atmospheric degradation of volatile organic compounds. Chemical Reviews, 103(12), 4605-4638 (2003).
2. Blanchard, C. L., & Tanenbaum, S. J., Differences between weekday and weekend air pollutant levels in southern California. Journal of the Air & Waste Management Association, 53(7), 816-828 (2003).
3. Banta, R. M., Senff, C. J., Nielsen-Gammon, J., Darby, L. S., Ryerson, T. B., Alvarez, R. J., ... & Trainer, M., A bad air day in Houston. Bulletin of the American Meteorological Society, 86(5), 657-670 (2005).
4. Berkowitz, C. M., Spicer, C. W., & Doskey, P. V., Hydrocarbon observations and ozone production rates in Western Houston during the Texas 2000 Air Quality Study. Atmospheric Environment, 39(19), 3383-3396 (2005).
5. Couzo, E., Jeffries, H. E., & Vizuete, W., Houston’s rapid ozone increases: preconditions and geographic origins. Environmental Chemistry, 10(3), 260-268 (2013).
6. Daum, P. H., Kleinman, L. I., Springston, S. R., Nunnermacker, L. J., Lee, Y. N., Weinstein‐Lloyd, J., ... & Berkowitz, C. M., A comparative study of O3 formation in the Houston urban and industrial plumes during the 2000 Texas Air Quality Study. Journal of Geophysical Research: Atmospheres, 108(D23) (2003).
7. Elkus, B., & Wilson, K. R., Photochemical air pollution: weekend-weekday differences. Atmospheric Environment, 11(6), 509-515 (1977).
8. Gan, F., & Hopke, P. K., Data mining of the relationship between volatile organic components and transient high ozone formation. Analytica Chimica Acta, 490(1-2), 153-158 (2003).
9. Kleinman, L. I., Daum, P. H., Imre, D., Lee, Y. N., Nunnermacker, L. J., Springston, S. R., ... & Rudolph, J., Ozone production rate and hydrocarbon reactivity in 5 urban areas: A cause of high ozone concentration in Houston. Geophysical Research Letters, 29(10), 105-1 (2002).
10. Murphy, C. F., & Allen, D. T., Hydrocarbon emissions from industrial release events in the Houston-Galveston area and their impact on ozone formation. Atmospheric Environment, 39(21), 3785-3798 (2005).
11. Ngan, F., & Byun, D., Classification of weather patterns and associated trajectories of high-ozone episodes in the Houston–Galveston–Brazoria area during the 2005/06 TexAQS-II. Journal of Applied Meteorology and Climatology, 50(3), 485-499 (2011).
12. Parrish, D. D., Ryerson, T. B., Mellqvist, J., Johansson, J., Fried, A., Richter, D., ... & Herndon, S. C., Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region. Atmospheric Chemistry and Physics, 12(7), 3273-3288 (2012).
13. Parra, R., & Franco, E., Identifying the Ozone Weekend Effect in the air quality of the northern Andean region of Ecuador. WIT Transactions Ecology and the Environment, 207, 169-180 (2016).
14. Ryerson, T. B., Trainer, M., Angevine, W. M., Brock, C. A., Dissly, R. W., Fehsenfeld, F. C., ... & Senff, C. J., Effect of petrochemical industrial emissions of reactive alkenes and NOx on tropospheric ozone formation in Houston, Texas. Journal of Geophysical Research: Atmospheres, 108(D8) (2003).
15. Rappenglück, B., Dasgupta, P. K., Leuchner, M., Li, Q., & Luke, W., Formaldehyde and its relation to CO, PAN, and SO2 in the Houston-Galveston airshed. Atmospheric Chemistry and Physics, 10(5), 2413-2424 (2010).
16. Sillman, S., The use of NOy, H2O2, and HNO3 as indicators for ozone‐NOx‐hydrocarbon sensitivity in urban locations. Journal of Geophysical Research: Atmospheres, 100(D7), 14175-14188 (1995).
17. Sillman, S., & Samson, P. J., Impact of temperature on oxidant photochemistry in urban, polluted rural and remote environments. Journal of Geophysical Research: Atmospheres, 100(D6), 11497-11508 (1995).
18. Solberg, S., Schmidbauer, N., Semb, A., Stordal, F., & Hov, Ø., Boundary-layer ozone depletion as seen in the Norwegian Arctic in spring. Journal of Atmospheric Chemistry, 23, 301-332 (1996).
19. Sarker, S., Kommalapati, R. R., & Huque, Z., Influence of reactive volatile organic compounds on ozone production in Houston-Galveston-Brazoria area. Journal of Environmental Protection, 6(04), 399 (2015).
20. Su, L., Yuan, Z., Fung, J. C., & Lau, A. K., A comparison of HYSPLIT backward trajectories generated from two GDAS datasets. Science of the Total Environment, 506, 527-537 (2015).
21. Tonnesen, G. S., & Dennis, R. L., Analysis of radical propagation efficiency to assess ozone sensitivity to hydrocarbons and NOx: 1. Local indicators of instantaneous odd oxygen production sensitivity. Journal of Geophysical Research: Atmospheres, 105(D7), 9213-9225 (2000).
22. Vizuete, W., Kim, B. U., Jeffries, H., Kimura, Y., Allen, D. T., Kioumourtzoglou, M. A., ... & Henderson, B., Modeling ozone formation from industrial emission events in Houston, Texas. Atmospheric Environment, 42(33), 7641-7650 (2008).
23. Vizuete, W., Jeffries, H. E., Tesche, T. W., Olaguer, E. P., & Couzo, E., Issues with ozone attainment methodology for Houston, TX. Journal of the Air & Waste Management Association, 61(3), 238-253 (2011).
24. Webster, M., Nam, J., Kimura, Y., Jeffries, H., Vizuete, W., & Allen, D. T., The effect of variability in industrial emissions on ozone formation in Houston, Texas. Atmospheric Environment, 41(40), 9580-9593 (2007).
25. Washenfelder, R. A., Trainer, M., Frost, G. J., Ryerson, T. B., Atlas, E. L., De Gouw, J. A., ... & Zheng, W., Characterization of NOx, SO2, ethene, and propene from industrial emission sources in Houston, Texas. Journal of Geophysical Research: Atmospheres, 115(D16) (2010).