Boundary-layer features and regional transport process of an extreme haze pollution event in Nanjing, China

Liu, Duanyang; Yan, Wenlian; Kang, Zhiming; Anning, Liu; Zhu, Yi

doi:10.1016/j.apr.2018.04.009

Cited by 18 publications

(9 citation statements)

References 58 publications

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“…Local emissions, pollutants transported from the North China Plain, and boundary layer change can all affect the intensity and duration of the fog-haze episode (Liang et al, 2017;Wang et al, 2016;Yu et al, 2016). The atmosphere boundary layer conditions in the Jianghuai area, which covers Jiangsu and Anhui provinces in this article, can affect not only local pollutant concentration but also pollutant transportation between North China and the Yangtze River Delta (Dai et al, 2020;Gu et al, 2020;Liu et al, 2018a;Liu et al, 2018b;Peng et al, 2016;Shen et al, 2021a;Shen et al, 2021b;Xie et al, 2021;Zhou et al, 2021).…”

Section: Introductionmentioning

confidence: 91%

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

Liu

Yan

Qian

et al. 2021

Front. Environ. Sci.

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The Jianghuai area is an “important” region not only for its local pollutant accumulation but the belt for pollutant transportation between North China and the Yangtze River Delta during the winter half of the year (often from October to next February). In this study, a movable boundary layer conceptual model for the Jianghuai area in the winter half of the year is established based on the analyses of characteristics of atmospheric circulations and boundary layer dynamic conditions. This conceptual model can well explain the causes of air quality change and frequent fog-haze episodes. Variations of the intensity and range of the cold and warm fronts in the Jianghuai area in the winter half of the year lead to form a movable boundary in this area. When the southerly wind is strong, or affected by strong cold air mass, the air quality in the Jianghuai area may be excellent with a low air pollution index; Two atmospheric circulations provide favorable conditions for the fog-haze formation and maintenance in Jianghuai area: 1) When the shallow weak cold air mass is below the deep moist warm air mass, a stable temperature inversion occurs. The pollutants are transported to the Jianghuai area by the weak cold air mass, and local emissions also accumulate. As a result, a severe air pollution episode appears. 2) When the northerly cold air mass is as intense as the southerly moist warm air mass, the pollutants transported from North China as well as local emissions will continuously accumulate in the study area, which may lead to more severe air pollution. This conceptual model can help us analyze atmospheric diffusion capacity, and benefit the forecast and early warning of airflow stagnation area and fog-haze episode.

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Section: Introductionmentioning

confidence: 91%

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

Liu

Yan

Qian

et al. 2021

Front. Environ. Sci.

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“…The interactions of thermodynamic and dynamic factors strengthen the downward transport of PM 2.5 to the surface layer for haze pollution in the receptor region of Fuzhou. However, the recent study in YRD found that the downward momentum transport by the weak cold front increased surface wind speeds, destroyed the inversions, and ended the haze event (D. Liu et al., 2018); thus, the general mechanisms of haze arising under calm boundary conditions and dissipating under unstable boundary conditions are not fully applicable to the clean regions that receive pollutants.…”

Section: Unstable Atmospheric Boundary Layer In Pm25 Pollution Episodesmentioning

confidence: 99%

Haze Pollution in the Unstable Atmospheric Boundary Layer Over the West Bank of Taiwan Strait Induced by Regional Transport of PM_2.5

Jiang

Zhao

Tan

et al. 2022

Earth and Space Science

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The regional transport of air pollutants is an important process in determining regional air quality variations (Carroll & Dixon, 2002). In general, the atmospheric transport is mainly controlled by the vertical structure of the atmospheric boundary layer and atmospheric circulation. Globally, air pollutants can be transported from East Asia to North America (Y. Zhang et al., 2010).The wind near surface is important for air pollutant transport. The wind direction and speed largely affect the quantity and direction of transport (H. Wang et al., 2019). In the East Asia monsoon region, the prevailing wind directions are northeast during winter half year and southwest during summer half year. The large-scale weather systems, such as continental cold highs and tropical cyclones, would drive regional transport of air pollutants from seriously polluted areas to other areas in East Asia (Chen et al., 2014;Shan et al., 2009). Also, the transport sources and paths of downwind regions are different due to the seasonal variation of prevailing wind directions (Hagler et al., 2006). The Yangtze River Delta (YRD) and North China Plain (NCP) in East China are considered to be the major emission regions. In previous studies, the transport of pollutants from the YRD and NCP accounts for a large proportion of air pollution episodes in other regions of East China (Z. F. Wang et al., 2014). During a regional transport process, the NCP was considered to be a source region of the YRD (J. . Similarly, East China could contribute ∼100 μg•m −3 of PM 2.5 to Beijing (in NCP) with the continuous southerly wind in several winter haze episode during 2010(L. Zhang, Wang, et al., 2015. The transport within the NCP contributed 70% of the PM 2.5 to Beijing (L. . Even though high proportion of exogenous pollutants leads to several haze cases in East China, the secondary aerosol could generated and accumulate for local high concentration of PM 2.5 under stable meteorological conditions in such high-emission regions of the YRD and NCP (M.

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“…When the light precipitation occurred on RPHPDs in Jiangsu, RH values increased to 83%-100%, high RH promoted the hygroscopic growth of pollutants [42], which can be explained by the Köhler's theory [43]. The rise of RH and hygroscopic growth altered the particle size and aggravated the pollutant accumulation [44][45][46].…”

Section: Precipitationmentioning

confidence: 99%

Meteorological Variables and Synoptic Patterns Associated with Air Pollutions in Eastern China during 2013–2018

Dai

Liu

et al. 2020

IJERPH

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Steady meteorological conditions are important external factors affecting air pollution. In order to analyze how adverse meteorological variables affect air pollution, surface synoptic situation patterns and meteorological conditions during heavy pollution episodes are discussed. The results showed that there were 78 RPHPDs (regional PM 2.5 pollution days) in Jiangsu, with a decreasing trend year by year. Winter had the most stable meteorological conditions, thus most RPHPDs appeared in winter, followed by autumn and summer, with the least days in spring. RPHPDs were classified into three patterns, respectively, as equalized pressure (EQP), advancing edge of a cold front (ACF) and inverted trough of low pressure (INT) according to the SLP (sea level pressure). RPHPDs under EQP were the most (51%), followed by ACF (37%); INT was the minimum (12%). Using statistical methods and meteorological condition data on RPHPDs from 2013 to 2017 to deduce the thresholds and 2018 as an independent dataset to validate the proposed thresholds, the threshold values of meteorological elements are summarized as follows. The probability of RPHPDs without rain was above 92% with the daily and hourly precipitation of all RPHPDs below 2.1 mm and 0.8 mm. Wind speed, RHs, inversion intensity(ITI), height difference in the temperature inversion(ITK), the lower height of temperature inversion (LHTI) and mixed-layer height (MLH) in terms of 25%-75% high probability range were respectively within 0.5-3.6 m s −1 , 55%-92%, 0.7-4.0 • C 100 m −1 , 42-576 m, 3-570 m, 200-1200 m. Two conditions should be considered: whether the pattern was EQP, ACF or INT and whether the eight meteorological elements are within the thresholds. If both criteria are met, PM 2.5 particles tend to accumulate and air pollution diffusion conditions are poor. Unfavorable meteorological conditions are the necessary, but not sufficient condition for RPHPDs.

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Boundary-layer features and regional transport process of an extreme haze pollution event in Nanjing, China

Cited by 18 publications

References 58 publications

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

Haze Pollution in the Unstable Atmospheric Boundary Layer Over the West Bank of Taiwan Strait Induced by Regional Transport of PM_2.5

Meteorological Variables and Synoptic Patterns Associated with Air Pollutions in Eastern China during 2013–2018

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Boundary-layer features and regional transport process of an extreme haze pollution event in Nanjing, China

Cited by 18 publications

References 58 publications

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

A Movable Fog-Haze Boundary Layer Conceptual Model Over Jianghuai Area, China

Haze Pollution in the Unstable Atmospheric Boundary Layer Over the West Bank of Taiwan Strait Induced by Regional Transport of PM2.5

Meteorological Variables and Synoptic Patterns Associated with Air Pollutions in Eastern China during 2013–2018

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Haze Pollution in the Unstable Atmospheric Boundary Layer Over the West Bank of Taiwan Strait Induced by Regional Transport of PM_2.5