Synoptic conditions associated with high carbon monoxide episodes at a coastal station in Hong Kong

Chung, Kyung-Won; Chan, Johnny C. L.; Ng, C. N.; Lam, K.S.; Wang, Tao

doi:10.1016/s1352-2310(97)00328-2

Cited by 24 publications

(19 citation statements)

References 6 publications

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“…Generally, when the northerly monsoons were enhanced, the CO levels were dramatically increased at both sites (for example, 30 October-1 November and 18-19 November). Chung et al (1999) investigated the relationship between high CO episodes and synoptic conditions at a coastal station in Hong Kong and found similar features as well. In contrast to CO, the O 3 levels had a decreasing trend with enhanced northerly monsoons at both sites (for example, 30 October-1 …”

Section: Day-to-day Variationsmentioning

confidence: 81%

Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport

et al. 2009

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Abstract. An intensive field measurement study was conducted simultaneously at a site within the inland Pearl River Delta (PRD) region (WQS) and a site in Hong Kong (TC) between 22 October and 1 December 2007. Ambient air pollutants measured included O 3 , NO x , CO, SO 2 , NMHCs, and carbonyls. The purpose is to improve our understanding of the interplay among local and regional air pollutants in the Hong Kong area, and the influence of regional transport on local air pollutants. The results indicate that the mean levels of air pollutants at the WQS site were much higher than those at the TC site, except NO x . Thirteen O 3 episode days (daily O 3 peak in excess of 122 ppbv) were monitored at WQS during the study period, while only 2 days were recorded at TC. Diurnal variations of O 3 showed higher nighttime levels of O 3 at TC than at WQS as well as more photochemical activity at WQS than TC. Remarkable differences in diurnal variations were also found between high and low O 3 pollution days at each site, implying that Hong Kong is more acutely VOC-limited than the inland PRD region. Ratio analyses for trace gases and VOCs and back trajectory calculation revealed that the air masses arriving at WQS were more aged due to regional influence, whereas the air masses at TC were mainly affected by local emissions and/or regional transport. In addition, the influence of regional transport from Eastern China on the primary pollutants of Hong Kong was noticeable, whereas the air masses from the inland PRD region (e.g. Dongguan and Huizhou) had significant influence on the air pollutants at WQS, and the anthropogenic emissions Correspondence to: H. Guo (ceguohai@polyu.edu.hk) in Eastern PRD (e.g. Shenzhen) played an important role on the photochemical ozone pollution in Western Hong Kong. These results confirm that regional and sub-regional transport of air pollution has a complex and significant impact on local air pollutants in this region.

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Section: Day-to-day Variationsmentioning

confidence: 81%

Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport

et al. 2009

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“…Similar meteorological conditions are also responsible for the majority of CO episodes in Hong Kong. 4 Clusters 1W and 4W are associated with cyclonic circulation, cloudiness, and low minimum temperature. These conditions are responsible for enhanced needs of central heating as well as for the "cold start" of vehicles that leads to CO production.…”

Section: Cold Periodmentioning

confidence: 99%

“…[1][2][3][4][5] All these works mainly concentrate on air pollution episodic events, especially for O 3 and other gaseous pollutants. Chung et al 4 found IMPLICATIONS This study correlates objectively defined synoptic circulation types with air pollution levels in Athens. These synoptic types are correlated with pollutant concentrations in objectively defined zones that present homogeneous air quality characteristics.…”

Section: Introductionmentioning

confidence: 99%

On the Relation between Seasonal Synoptic Circulation Types and Spatial Air Quality Characteristics in Athens, Greece

Kassomenos

Sindosi

Lolis

et al. 2003

Journal of the Air & Waste Management Association

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The impact of weather on air pollution was examined and evaluated for the city of Athens, Greece. We used an objectively defined synoptic classification scheme consisting of six summer and eight winter circulation types. This scheme was established using a combination of both factor and cluster analysis during 1954 -1999. Surface and isobaric levels of 850 hPa data were used. Factor analysis combined with cluster analysis was used to derive circulation types based on surface meteorological data for the period 1954 -1999 in Athens and on surface pressure grid data. The city was divided into three sectors according to the financial and social activities of the residents. To examine the spatial characteristics of pollutant concentrations over Athens for each synoptic type, the synoptic circulation types were then correlated with both gaseous and particulate pollutant concentrations measured in each sector between 1983 and 1999. Finally, extreme and severe episodic events were studied in terms of their meteorological and synoptic characteristics.

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“…Uplifted CO usually has a longer lifetime and can be transported fast by the upper layer winds over long distances through continents and between hemispheres in the troposphere (Stohl, 2001;Stohl et al, 2002;Damoah et al, 2004). Uplifting air mass from the surface to FT generally takes place by three processes: (1) frontal lifting, (2) orographic lifting, and (3) deep convection (Brown et al, 1984;Banic et al, 1986;Dickerson et al, 1987;Bethan et al, 1998;Pickering et al, 1998;Chung et al, 1999;Donnell et al, 2001;Kowol-Santen et al, 2001;Cooper et al, 2002;Liu et al, 2003;Miyazaki et al, 2003;Chan et al;Mari et al, 2004;Liu et al, 2006;Kar et al, 2008;Zhao et al, 2008;Ding et al, 2009;Randel et al, 2010;Chen et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Uplifting of carbon monoxide from biomass burning and anthropogenic sources to the free troposphere in East Asia

et al. 2015

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Abstract. East Asia has experienced rapid development with increasing carbon monoxide (CO) emission in the past decades. Therefore, uplifting CO from the boundary layer to the free troposphere in East Asia can have great implications on regional air quality around the world. It can also influence global climate due to the longer lifetime of CO at higher altitudes. In this study, three cases of high CO episodes in the East China and a trajectory dispersion model FLEXPART, we found different CO signatures in the elevated CO and distinct transport pathways and mechanisms for these cases. In the 2003 case, emissions from large forest fires near Lake Baikal dominated the elevated CO, which had been rapidly transported upward by a frontal system from the fire plumes. In the 2004 case, anthropogenic CO from the North China Plain experienced frontal lifting and mostly reached ∼ 700 hPa near the East China Sea, while CO from biomass burning over Indochina experienced orographic lifting, lee-side-troughinduced convection, and frontal lifting through two separate transport pathways, leading to two distinct CO enhancements around 700 and 300 hPa. In the 2005 case, the observed CO of ∼ 300 ppbv around 300 hPa originated from anthropogenic sources over the Sichuan Basin and the North China Plain and from forest fires over Indochina. The high CO was transported to such altitudes through strong frontal lifting, interacting with convection and orographic lifting. These cases show that topography affects vertical transport of CO in East Asia via different ways, including orographic uplifting over the Hengduan Mountains, assisting frontal lifting in the North China Plain, and facilitating convection in the Sichuan Basin. In particular, topography-induced lee-side troughs over Indochina led to strong convection that assisted CO uplifting to the upper troposphere. This study shows that the new daytime MOPITT near-infrared (NIR) and thermalinfrared (TIR) data (version 5 or above) have enhanced vertical sensitivity in the free troposphere and may help qualitative diagnosis of vertical transport processes in East Asia.

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Synoptic conditions associated with high carbon monoxide episodes at a coastal station in Hong Kong

Cited by 24 publications

References 6 publications

Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport

Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport

On the Relation between Seasonal Synoptic Circulation Types and Spatial Air Quality Characteristics in Athens, Greece

Uplifting of carbon monoxide from biomass burning and anthropogenic sources to the free troposphere in East Asia

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