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

Huang, Tao; Yang, Yibo; O’Connor, Ewan; Lolli, Simone; Haywood, Jim M.; Osborne, Martin J.; Cheng, Jack C. H.; Guo, Jianping; Yim, Steve Hung Lam

doi:10.1016/j.envpol.2021.116534

Cited by 26 publications

(17 citation statements)

References 49 publications

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“…That is because air pollution is strongly related to atmospheric conditions, and typhoon circulation typically alters atmospheric stability and air pollutant diffusion in specific locations. For example, researchers revealed that ozone episodes in Hong Kong and southeastern China are strongly related to the passage of typhoons as they approach the area (Lee et al, 2002;Ding et al, 2004;Huang et al, 2005Huang et al, , 2006Yang et al, 2012;Zhang et al, 2013Zhang et al, , 2014Wei et al, 2016;Yan et al, 2016;Luo et al, 2018;Deng et al, 2019;Huang et al, 2021). The stagnant meteorological conditions associated with strong subsidence and stable stratification in the boundary layer result in pollutant accumulation before typhoons make landfall.…”

Section: Introductionmentioning

confidence: 99%

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

et al. 2021

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Abstract. Air pollution is typically at its lowest in Taiwan during summer. The mean concentrations of PM10, PM2.5, and daytime ozone (08:00–17:00 LST) during summer (June–August) over central Taiwan were 35–40 µg m−3, 18–22 µg m−3, and 30–42 ppb, respectively, between 2004 and 2019. Sampling analysis revealed that the contribution of organic carbon (OC) to PM2.5 could have exceeded 30 % in urban and inland mountain sites during July in 2017 and 2018. Frequent episodes of air quality deterioration occur over the western plains of Taiwan when an easterly typhoon circulation interacts with the complex topographic structure of the island. We explored an episode of air quality deterioration that was associated with a typhoon between 15 and 17 July 2018 using the Weather Research Forecasting with Chemistry (WRF-Chem) model. The results indicated that the continual formation of low-pressure systems or typhoons in the area between Taiwan and Luzon island in the Philippines provided a strong easterly ambient flow, which lasted for an extended period between 15 and 17 July. The interaction between the easterly flow and Taiwan's Central Mountain Range (CMR) resulted in stable weather conditions and weak wind speed in western Taiwan during the study period. Numerical modeling also indicated that a lee side vortex easily formed, and the wind direction could have changed from southwesterly to northwesterly over central Taiwan because of the interaction between the typhoon circulation and the CMR. The northwesterly wind coupled with a sea breeze was conducive to the transport of air pollutants from the coastal upstream industrial and urban areas to the inland area. The dynamic process for the wind direction changed given a reasonable explanation for why the observed SO42- became the major contributor to PM2.5 during the episode. SO42- contribution proportions (%) to PM2.5 at the coastal, urban, and mountain sites were 9.4 µg m−3 (30.5 %), 12.1 µg m−3 (29.9 %), and 11.6 µg m−3 (29.7 %), respectively. Moreover, the variation of the boundary layer height had a strong effect on the concentration level of both PM2.5 and ozone. The lee vortex and land–sea breeze, as well as the boundary layer development, were the key mechanisms in air pollutant accumulation and transport. As typhoons frequently occur around Taiwan during summer and fall, their effect on the island's air quality merits further research attention.

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Section: Introductionmentioning

confidence: 99%

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

et al. 2021

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“…Nevertheless, considering the impact of focus length, we derived the validated 𝐴𝐴 𝐴𝐴 with a known telescope focus function retrieved from a nominally identical Halo Photonics StreamLine LiDAR and a synergetic ceilometer measurement in Finland (Pentikäinen et al, 2020). Detailed calibration of the 𝐴𝐴 𝐴𝐴 can be found in Pentikäinen et al (2020) and Huang et al (2021).…”

Section: Aerosol Particles and Turbulent Mixingmentioning

confidence: 99%

“…LiDAR measurements and processed data during the selected cases can be found in the open data repository: Huang, Tao et al. (2021): LiDAR observations in 2020 for aerosol‐cloud interaction. 4TU.ResearchData.…”

Section: Data Availability Statementmentioning

confidence: 99%

“…Over East and Southeast Asia, thunderstorms and air pollution are frequently connected under large‐scale forcing. A tropical cyclone (TC) that forms over the northwest Pacific typically generates flow from inland areas (from north to south) at upper‐level over its surrounding regions such as Hong Kong and the Greater Bay Area (GBA; Chow et al., 2018; Deng et al., 2019; Huang et al., 2021). To attribute the local‐scale air pollution to large‐scale TC impacts, long‐term statistics of ground‐level PM 10 /ozone (O 3 ) concentration with mesoscale meteorological profiles have been generated and the positions of TC can explain most of the occurrence of air pollution episodes in Hong Kong (Chow et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

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Regime‐Dependent Impacts of Aerosol Particles and Updrafts on the Cloud Condensation Nuclei and the Enhanced Warm Rain Suppression: Evidence From Synergistic Satellite and LiDAR Observations

Huang

Zhu

Yang

et al. 2022

Geophysical Research Letters

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Aerosol particles, especially those from anthropogenic activities, can serve as cloud condensation nuclei (CCN), thus substantially influence the organization of cloud systems at various scales (Fan et al., 2008;van den Heever & Cotton, 2007;Wang et al., 2011). The number of CCN can alter the cloud properties by determining the rate of cloud droplet growth and size distribution, especially in convective clouds that are frequently initiated in the atmospheric boundary layer (ABL) (Cao et al., 2021;Twomey, 1977;Zhang et al., 2021). This interaction has been regarded as one of the largest uncertainties both in weather forecast and climate projections (IPCC, 2013). Hence, better understandings of the mechanisms of aerosol-cloud interaction are urgently required.Aerosol-cloud interaction substantially changes cloud microphysics, which influence the autoconversion process whereby cloud droplets grow to sizes beyond which precipitation occurs and can thus influence warm rain

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“…These weather conditions are conducive to O 3 and secondary PM 2.5 formation. The impacts of TCs on O 3 and PM 2.5 pollution in China were first noticed in Hong Kong and the Pearl River Delta (PRD) region (Huang et al, 2005(Huang et al, , 2006(Huang et al, , 2021Lin et al, 2021;Qu et al, 2021). Scholars have identified that TC is one of the most important weather systems that causes O 3 and PM 2.5 pollution in southern China.…”

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confidence: 99%

Co‐Occurrence of Surface O₃, PM_2.5 Pollution, and Tropical Cyclones in China

et al. 2022

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Extreme weather events are on the rise against the backdrop of climate change. Impact of tropical cyclone (TC) system, one of the extreme weather events, on air pollution remain poorly understood. A total of 103 recorded TCs (tropical storms and stronger) together with the surface air quality data collected from over 2000 observational sites in mainland China in 2014–2020 were utilized to examine the co‐occurrence of TC with continental ozone (O3) and fine particulate matters (PM2.5) pollution. TCs exhibit cleaning effects on PM2.5 within its coverage (typically ∼650 km), but enhance the co‐occurrence of O3 and PM2.5 in an extended region. The co‐occurrence frequencies are greater than 30% for any two co‐occurring events, and ∼8% for TC + PM2.5 + O3. We observed superregional trans‐boundary transportation of air pollutants driven by TC, led to ubiquitous spatial offsets and temporal lags of O3, PM2.5 pollution and TC, which are often inconsistent with traditional mechanisms such as accelerated chemical reactions for O3 formation. O3 pollution tends to occur 1∼2 days after PM2.5 pollution moved west. In contrast, PM2.5 pollution usually occur 4–12 hr following O3 pollution within a day over most regions except the southeast of China. Such spatial and temporal offsets vary with the paths of TCs. Composite analysis shows that temperature, wind field and large pressure systems are the key factors for air pollution formation and transportation over TC periphery. Our results have implications for understanding the interactions between TCs and air pollution, particularly for coastal areas where there are recurring TCs.

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

Cited by 26 publications

References 49 publications

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

Regime‐Dependent Impacts of Aerosol Particles and Updrafts on the Cloud Condensation Nuclei and the Enhanced Warm Rain Suppression: Evidence From Synergistic Satellite and LiDAR Observations

Co‐Occurrence of Surface O₃, PM_2.5 Pollution, and Tropical Cyclones in China

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

Cited by 26 publications

References 49 publications

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

Regime‐Dependent Impacts of Aerosol Particles and Updrafts on the Cloud Condensation Nuclei and the Enhanced Warm Rain Suppression: Evidence From Synergistic Satellite and LiDAR Observations

Co‐Occurrence of Surface O3, PM2.5 Pollution, and Tropical Cyclones in China

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Co‐Occurrence of Surface O₃, PM_2.5 Pollution, and Tropical Cyclones in China