Hong Kong is a megacity of 7 million people in the Pearl River Delta Region of China, which has a total population of 120 million. In the fall of 2013, our group traveled to there to make the first measurements of nighttime chemistry within the residual layer (the remnant of the previous day’s convective boundary layer) in Asia. We collaborated with the group of Professor Tao Wangat Hong Kong Polytechnic University. The sampling site was at the summit of Tai Mo Shan (translation: “Big Hat Mountain”), the highest point in Hong Kong and 950 m above Sea Level. The site mainly experienced inflow from the south China sea, with aged air pollution that had been transported from the North China Plain. Several nighttime events entrained air with high concentrations of urban pollution from the megacity of Guangzhou, with high levels of N2O5(up to 12 ppbv) and ClNO2(up to 4.8 ppbv). Subsequent modeling demonstrated the influence of this nighttime chemistry on next-day ozone in the region through chlorine activation reactions.
Selected Papers
Brown, S.S., W.P. Dubé, Y.J. Tham, Q. Zha, L. Xue, S. Poon, Z. Wang, D.R. Blake, W. Tsui, D.D. Parrish, and T. Wang, Nighttime chemistry at a high altitude site above Hong Kong. Journal of Geophysical Research: Atmospheres, 2016. 121(5): p. 2457-2475. http://dx.doi.org/10.1002/2015JD024566
Wang, T., Y.J. Tham, L. Xue, Q. Li, Q. Zha, Z. Wang, S.C.N. Poon, W.P. Dubé, D.R. Blake, P.K.K. Louie, C.W.Y. Luk, W. Tsui, and S.S. Brown, Observations of nitryl chloride and modeling its source and effect on ozone in the planetary boundary layer of southern China. Journal of Geophysical Research: Atmospheres, 2016. 121(5): p. 2476-2489. http://dx.doi.org/10.1002/2015JD024556