Characteristics of Heavy Particulate Matter Pollution Events Over Hong Kong and Their Relationships With Vertical Wind Profiles Using High-Time-Resolution Doppler Lidar Measurements

This is the final version. Available from American Geophysical Union (AGU) via the DOI in this record. 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.Chinese University of Hong Kong ‐ University of Exeter Joint Centre for Environmental Sustainability and Resilience (ENSURE)The Chinese University of Hong Kon

Assessing Transboundary-Local Aerosols Interaction Over Complex Terrain Using a Doppler LiDAR Network

This is the final version. Available from Wiley via the DOI in this recordData Availability Statement: Surface metrological data sets in Hong Kong are available at Hong Kong Observatory’s website: https://www.hko.gov.hk/en/cis/climat.htm. PM2.5 concentrations data sets can be obtained from Hong Kong Environmental Protection Department: https://www.aqhi.gov.hk/en.html. Processed 3DREAMS LiDAR data set and HKIA LiDAR data sets can be obtained in the repository: https://figshare.com/s/78e928f29c57ff86b5eeTransboundary-local aerosols interaction requires to be comprehensively understood in urban air quality research. A year-long intensive observation of the atmospheric boundary layer (ABL) at multiple sites in Hong Kong was conducted using a four-Doppler Light Detection and Ranging (LiDAR) network with different scanning modes. Results show that heterogeneity of the ABL in terms of mixing layer height and wind shear was induced by orographic topography. Interaction between local and advected aerosol layers during a transboundary air pollution (TAP) episode was identified by the network. During TAP episode, downward transport of transboundary aerosol relied on small scale eddies with weak wind speed in nighttime, while the transport of surface local aerosol to upper level was the dominated process in daytime, but the heterogeneity of the ABL affected by terrain determined the capacity of the mixing, eventually resulting in the opposite transport direction of aerosols in the transboundary-local aerosols interaction.Dr. Stanley Ho Medicine Development FoundationVice-Chancellor’s Discretionary Fund of The Chinese University of Hong Kon

Characterizing the performance of a POPS miniaturized optical particle counter when operated on a quadcopter drone

This is the final version. Available from European Geosciences Union / Copernicus Publications via the DOI in this record. The data presented in this study can be provided upon reasonable request from Zixia Liu ([email protected]).We first validate the performance of the Portable Optical Particle Spectrometer (POPS), a small light-weight and high sensitivity optical particle counter, against a reference scanning mobility particle sizer (SMPS) for a month-long deployment in an environment dominated by biomass burning aerosols. Subsequently, we examine any biases introduced by operating the POPS on a quadcopter drone, a DJI Matrice 200 V2. We report the root mean square difference (RMSD) and mean absolute difference (MAD) in particle number concentrations (PNCs) when mounted on the UAV and operating on the ground and when hovering at 10 m. When wind speeds are low (less than 2.6 m s−1), we find only modest differences in the RMSDs and MADs of 5 % and 3 % when operating at 10 m altitude. When wind speeds are between 2.6 and 7.7 m s−1 the RMSDs and MADs increase to 26.2 % and 19.1 %, respectively, when operating at 10 m altitude. No statistical difference in PNCs was detected when operating on the UAV in either ascent or descent. We also find size distributions of aerosols in the accumulation mode (defined by diameter, d, where 0.1 ≤ d ≤ 1 µm) are relatively consistent between measurements at the surface and measurements at 10 m altitude, while differences in the coarse mode (here defined by d > 1 µm) are universally larger. Our results suggest that the impact of the UAV rotors on the POPS PNCs are small at low wind speeds, but when operating under a higher wind speed of up to 7.6 m s−1, larger discrepancies occur. In addition, it appears that the POPS measures sub-micron aerosol particles more accurately than super-micron aerosol particles when airborne on the UAV. These measurements lay the foundations for determining the magnitude of potential errors that might be introduced into measured aerosol particle size distributions and concentrations owing to the turbulence created by the rotors on the UAV.Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Chinese University of Hong KongUniversity of Exete

Air quality and climate impacts of alternative bus technologies in Greater London

The environmental impact of diesel-fueled buses can potentially be reduced by the adoption of alternative propulsion technologies such as lean-burn compressed natural gas (LB-CNG) or hybrid electric buses (HEB), and emissions control strategies such as a continuously regenerating trap (CRT), exhaust gas recirculation (EGR), or selective catalytic reduction with trap (SCRT). This study assessed the environmental costs and benefits of these bus technologies in Greater London relative to the existing fleet and characterized emissions changes due to alternative technologies. We found a >30% increase in CO 2 equivalent (CO2e) emissions for CNG buses, a <5% change for exhaust treatment scenarios, and a 13% (90% confidence interval 3.8-20.9%) reduction for HEB relative to baseline CO2e emissions. A multiscale regional chemistry-transport model quantified the impact of alternative bus technologies on air quality, which was then related to premature mortality risk. We found the largest decrease in population exposure (about 83%) to particulate matter (PM2.5) occurred with LB-CNG buses. Monetized environmental and investment costs relative to the baseline gave estimated net present cost of LB-CNG or HEB conversion to be 187 million (73 million to 301 million) or 36 million (-25 million to 102 million), respectively, while EGR or SCRT estimated net present costs were 19 million (7 million to 32 million) or 15 million (8 million to 23 million), respectively. © 2014 American Chemical Society

Determinants of personal exposure to fine particulate matter (PM2.5) in adult subjects in Hong Kong

202308 bcchAccepted ManuscriptRGCOthersFocused Innovations Scheme of the; Hong Kong Environmental Protection Department; Vice-Chancellor's Discretionary Fund; Faculty of Arts and Social Sciences, Carleton University; Chinese University of Hong KongPublishe

Estimation of personal exposure to fine particles (PM2.5) of ambient origin for healthy adults in Hong Kong

202308 bcchAccepted ManuscriptRGCOthersHong Kong Environmental Protection Department; Chinese University of Hong KongPublishe

The effects of particle-induced oxidative damage from exposure to airborne fine particulate matter components in the vicinity of landfill sites on Hong Kong

202308 bcchAccepted ManuscriptOthersFood and Health Bureau; Health and Medical Research FundPublishe

Evaluation of hazardous airborne carbonyls in five urban roadside dwellings : a comprehensive indoor air assessment in Sri Lanka

202308 bcchAccepted ManuscriptOthersClean Air Initiative Asia Center; Caja de Ahorros de la Inmaculada de AragónPublishe