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Characteristics of Heavy Particulate Matter Pollution Events Over Hong Kong and Their Relationships With Vertical Wind Profiles Using High‐Time‐Resolution Doppler Lidar Measurements
Author(s) -
Yang Yuanjian,
Yim Steve H.L.,
Haywood Jim,
Osborne Martin,
Chan Jazz C.S.,
Zeng Zhaoliang,
Cheng Jack C.H.
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd031140
Subject(s) - environmental science , lidar , wind speed , planetary boundary layer , wind shear , atmospheric sciences , particulates , pollution , wind direction , air quality index , meteorology , boundary layer , typhoon , particulate pollution , geology , geography , remote sensing , turbulence , ecology , physics , biology , thermodynamics
Previous studies have reported boundary layer features related to air pollution. However, few studies have comprehensively evaluated the characteristics and mechanisms of vertical wind in the formation and evolution of heavy particulate matter pollution episodes (EP) in Hong Kong. In this study, we analyzed the vertical characteristics of heavy particulate matter (PM) pollutions over Hong Kong and their relationships with vertical wind profiles using high‐time‐resolution Doppler lidar measurements and hourly meteorological and air quality observations. We identified nine EPs and show that the events were closely coupled to various vertical wind profiles in the planetary boundary layer (PBL). Our analysis suggests that strong vertical wind speed with wind shear at certain heights in the PBL had a positive correlation with surface PM during most superregional transboundary EPs. The maximum transport height extends from the surface to about 2.0 km or even higher; these transport heights differed among superregional and regional transboundary EPs. At peak surface pollution concentrations during the nine EPs, the surface PM 10 had a significant negative correlation with PBL heights/mixing layer heights, while the averaged wind shear in the PBL was significantly positively correlated. These EPs with different mixing layer heights were mainly driven by different vertical wind shear conditions under various weather systems related to surface high pressure, cold fronts, dust storms, and typhoons. This work provides scientific evidence that surface PM pollutions were closely related to the characteristics of vertical profiles during the transboundary air pollutions.