Heavy aerosol pollution episodes in winter Beijing enhanced by radiative cooling effects of aerosols

Zhong, Junting; Zhang, Xiaoye; Wang, Yaqiang; Liu, Cheng; Dong, Yunsheng

doi:10.1016/j.atmosres.2018.03.011

Cited by 80 publications

(46 citation statements)

References 29 publications

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“…This process has been referred to as the "dome effect" of BC, which played a vital role in the formation of prolonging haze events in the NCP during December 2013 [61•]. In addition, the light-scattering aerosols also play an important role in lowering BLH by cooling the land surface, which leads to an increase in RH and accumulations of aerosols [67,68].…”

Section: North China Plainmentioning

confidence: 99%

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Miao

et al. 2019

Curr Pollution Rep

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112

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Purpose of Review During the past decades, the number and size of megacities have been growing dramatically in China. Most of Chinese megacities are suffering from heavy PM 2.5 pollution. In the pollution formation, the planetary boundary layer (PBL) plays an important role. This review is aimed at presenting the current state of understanding of the PBL-PM 2.5 interaction in megacities, as well as to identify the main gaps in current knowledge and further research needs. Recent Findings The PBL is critical to the formation of urban PM 2.5 pollution at multiple temporal scales, ranging from diurnal change to seasonal variation. For the essential PBL structure/process in pollution, the coastal megacities have different concerns from the mountainous or landlocked megacities. In the coastal cities, the recirculation induced by sea-land breeze can accumulate pollutants, whereas in the valley/basin, the blocking effects of terrains can lead to stagnant conditions and thermal inversion. Within a megacity, although the urbanization-induced land use change can cause thermodynamic perturbations and facilitate the development of PBL, the increases in emissions outweigh this impact, resulting in a net increase of aerosol concentration. Moreover, the aerosol radiative effects can modify the PBL by heating the upper layers and reducing the surface heat flux, suppressing the PBL and exacerbating the pollution. Summary This review presented the PBL-PM 2.5 interaction in 13 Chinese megacities with various geographic conditions and elucidated the critical influencing processes. To further understand the complicated interactions, long-term observations of meteorology and aerosol properties with multi-layers in the PBL need to be implemented.

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Section: North China Plainmentioning

confidence: 99%

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Miao

et al. 2019

Curr Pollution Rep

Self Cite

112

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“…For a given amount of radiation change, nighttime winter temperature shows a larger change and sensitivity than that of daytime and difference in day and night summer temperatures (Pielke et al, ; Zhou et al, ). Modeling studies over the industrialized regions of East Asia have shown aerosol forcing on surface temperature and subsequent feedback on cloud cover with maximum change observed during winter (Ding et al, ; Huang et al, ; Zhong et al, ). In addition to the daytime surface cooling, Huang et al () observed that inclusion of aerosol feedback increases the nighttime downwelling longwave radiation resulting in warming of the earth surface (ΔT nighttime ∼ 0.7 °C).…”

Section: Resultsmentioning

confidence: 99%

“…A change in temperature of 1.0–1.5 °C was observed between 300 and 1,200 m by Ding et al () due to BC warming. Zhong et al () observed temperature inversion with the temperature difference of ∼4 °C within the boundary layer, during a heavy aerosol pollution event in winter over Beijing, China. The stable atmospheric stratification also decreases the turbulent diffusion of about 52% and a decrease in the boundary layer height by about 33% (Wang et al, ).…”

Section: Resultsmentioning

confidence: 99%

Modeling of the Effects of Wintertime Aerosols on Boundary Layer Properties Over the Indo Gangetic Plain

et al. 2019

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Wintertime fog and severe aerosol loading in the boundary layer over South Asia, especially Indo Gangetic Plain (IGP), causes disruptions in the day‐to‐day life of millions of people living in the region, and these heavy pollution episodes result in relentless effects on human health. Weather Research Forecasting model coupled with aerosol chemistry is used to investigate the radiative effects and feedbacks of aerosols on the evolution and structure of the planetary boundary layer over the region. In general, aerosols lead to cooling at the surface, which decreases the nonradiative fluxes (latent and sensible heat fluxes), weakens the turbulent diffusion, and inhibits/delays the growth of convective boundary layer. The impact was maximum over IGP where aerosol‐induced solar dimming (60–80 W/m2) led to a cooling of −0.6 to −2 ° C at the surface, which decreases the noontime boundary layer height by ∼200 m. This effect overwhelms the diabatic heating due to absorbing aerosols in the atmosphere. The significant decrease in sensible (∼11–23 W/m2) and latent heat flux (5–14 W/m2) was observed over IGP and western India. Aerosol boundary layer interaction increases the aerosol loading near the surface (PM2.5) by 3 to 30 μg/m3, which further deteriorate the air quality and visibility over the region. The aerosol forcing increases the relative humidity in the lower boundary layer and amplifies the aerosol forcing. The fog events over the Indian regions identified using INSAT‐3D observations coincide with the regions where aerosol‐boundary layer interactions are very significant. The aerosol‐boundary layer interaction has significance in forecasting fog events and planning mitigation strategies for improving the air quality over the region.

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“…The meteorological observation data from the weather tower show that applicability of the Monin-Oubhov similarity theory under stable conditions causes a significant error for T * or u * , while the Monin-Oubhov similarity theory is still basically applicable in the case of unstable stratification (Liu et al, 2009). In the roughness sub-layers of other cities, under the condition of unstable stratification, the local similarity theory is similar to MOST (Zou et al, 2015(Zou et al, , 2018. Because the height of the LAS instrument at the CAMS site was 43 m, during most of the time the conditions assumed for free convection were easily satisfied.…”

Section: Calculation Of the Aerosol Mass Vertical Fluxmentioning

confidence: 85%

Aerosol vertical mass flux measurements during heavy aerosol pollution episodes at a rural site and an urban site in the Beijing area of the North China Plain

et al. 2019

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Abstract. Due to excessive anthropogenic emissions, heavy aerosol pollution episodes (HPEs) often occur during winter in the Beijing–Tianjin–Hebei (BTH) area of the North China Plain. Extensive observational studies have been carried out to understand the causes of HPEs; however, few measurements of vertical aerosol fluxes exist, despite them being the key to understanding vertical aerosol mixing, specifically during weak turbulence stages in HPEs. In the winter of 2016 and the spring of 2017 aerosol vertical mass fluxes were measured by combining large aperture scintillometer (LAS) observations, surface PM2.5 and PM10 mass concentrations, and meteorological observations, including temperature, relative humidity (RH), and visibility, at a rural site in Gucheng (GC), Hebei Province, and an urban site at the Chinese Academy of Meteorological Sciences (CAMS) in Beijing located 100 km to the northeast. These are based on the light propagation theory and surface-layer similarity theory. The near-ground aerosol mass flux was generally lower in winter than in spring and weaker in rural GC than in urban Beijing. This finding provides direct observational evidence for a weakened turbulence intensity and low vertical aerosol fluxes in winter and polluted areas such as GC. The HPEs included a transport stage (TS), an accumulative stage (AS), and a removal stage (RS). During the HPEs from 25 to 31 January 2017, in Beijing, the mean mass flux decreased by 51 % from 0.0049 mg m−2 s−1 in RSs to 0.0024 mg m−2 s−1 in the TSs. During the ASs, the mean mass flux decreased further to 0.00087 mg m−2 s−1, accounting for approximately one-third of the flux in the TSs. A similar reduction from the TSs to ASs was observed in the HPE from 16 to 22 December 2016 in GC. It can be seen that from the TS to the AS, the aerosol vertical turbulent flux decreased, but the aerosol particle concentration within the surface layer increased, and it is inferred that in addition to the contribution of regional transport from upwind areas during the TS, suppression of vertical turbulence mixing confining aerosols to a shallow boundary layer increased accumulation.

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Heavy aerosol pollution episodes in winter Beijing enhanced by radiative cooling effects of aerosols

Cited by 80 publications

References 29 publications

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Modeling of the Effects of Wintertime Aerosols on Boundary Layer Properties Over the Indo Gangetic Plain

Aerosol vertical mass flux measurements during heavy aerosol pollution episodes at a rural site and an urban site in the Beijing area of the North China Plain

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