Influence of a weak typhoon on the vertical distribution of air pollution in Hong Kong: A perspective from a Doppler LiDAR network

Tao Huang; Yuanjian Yang; Ewan James O'Connor; Simone Lolli; Jim Haywood; Martin Osborne; Jack Chin-Ho Cheng; Jianping Guo; Steve Hung-Lam Yim

doi:10.1016/j.envpol.2021.116534

Influence of a weak typhoon on the vertical distribution of air pollution in Hong Kong: A perspective from a Doppler LiDAR network

Environ Pollut. 2021 May 1:276:116534. doi: 10.1016/j.envpol.2021.116534. Epub 2021 Jan 27.

Authors

Tao Huang¹, Yuanjian Yang², Ewan James O'Connor³, Simone Lolli⁴, Jim Haywood⁵, Martin Osborne⁵, Jack Chin-Ho Cheng¹, Jianping Guo⁶, Steve Hung-Lam Yim⁷

Affiliations

¹ Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong, China.
² School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, China; Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong, China.
³ Finnish Meteorological Institute, Helsinki, Finland; Department of Meteorology, University of Reading, Reading, UK.
⁴ CNR-IMAA, Istituto di Metodologie Ambientali, Tito (PZ), Italy; Department of Physics, Kent State University (Florence Campus), 44240, Kent, OH, USA.
⁵ Department of Mathematics, College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, UK; Met Office, Exeter, UK.
⁶ State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, 100081, China.
⁷ Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong, China; Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong, China; Stanley Ho Big Data Decision Analytics Research Centre, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: [email protected].

PMID: 33611194
DOI: 10.1016/j.envpol.2021.116534

Abstract

High particulate matter (PM) and ozone (O₃) concentration in Hong Kong are frequently observed during the summertime typhoon season. Despite the critical effect of a typhoon on air pollution, contributions of vertical wind profile and cloud movement during transboundary air pollution (TAP) on surface PM and O₃ concentration have yet to be fully understood. This work is the first study to apply a network of Doppler light detection and ranging (LiDAR) as well as back trajectory analysis to comprehensively analyze the effect of a weak Typhoon (Danas) occurring during 16-19 July 2019 on different variations in PM and O₃ concentration. During the typhoon Danas, three types of surface air pollution with five episodes were identified: (1) low PM and high O₃ concentration; (2) co-occurring high PM and O₃ concentration and (3) high PM and low O₃ concentration. Employing our 3D Real-Time Atmospheric Monitoring System (3DREAMs) along with surface observations, we found the important role of TAP in the increases in surface PM and O₃ concentration with significant vertical wind shear that transported air pollutants at upper levels, and strong vertical mixing that brought air pollutants to the ground level. Cloud movement related to typhoon periphery, as well as high solar radiation due to sinking motion and remote transport by continental wind, have an impact on local O₃ concentration. For the substantial difference in O₃ concentration between two air quality measurement sites, the similar vertical aerosol distributions and wind profiles suggest the comparable TAP contributions at the two sites and thus infer the critical role of local O₃ photochemical process in the O₃ difference. This work comprehensively reveals the influences of a weak typhoon on variations in PM and O₃ during the five episodes, providing important references for air quality monitoring and forecast in regions under the influence of typhoon.

Keywords: Air pollution; Ground-based LiDAR; Transport; Wind profile.

MeSH terms

Air Pollutants* / analysis
Air Pollution* / analysis
Cyclonic Storms*
Environmental Monitoring
Hong Kong
Ozone* / analysis

Substances

Air Pollutants
Ozone