Characteristics of Heavy Particulate Matter Pollution Events Over Hong Kong and Their Relationships With Vertical Wind Profiles Using High‐Time‐Resolution Doppler Lidar Measurements. Issue 16 (26th August 2019)

• Record Type: Journal Article
• Authors: Yang, Yuanjian; Yim, Steve H.L.; Haywood, Jim; Osborne, Martin; Chan, Jazz C.S.; Zeng, Zhaoliang; Cheng, Jack C.H.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 16(2019)
• Page Start: 9609
• Page End: 9623
• Publication Date: 2019-08-26
• Subjects: PM pollution -- transport -- Doppler lidar -- vertical wind profile -- mixing layer height; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2019JD031140
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: 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 PM10 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. Key Points: Transboundary particulate matter pollution episodes (EP) were mainly caused by surface high pressure, cold front, dust storm, or typhoons Vertical wind profiles show the different relationships between wind speed at various altitudes and surface particulate matter The maximum transport height extended from surface to about 2.0 km or even higher in superregional and regional transboundary EPs