scholarly journals Response of early winter haze in the North China Plain to autumn Beaufort sea ice

2019 ◽  
Vol 19 (3) ◽  
pp. 1439-1453 ◽  
Author(s):  
Zhicong Yin ◽  
Yuyan Li ◽  
Huijun Wang
Keyword(s):  
North China Plain ◽  
North China ◽  
Beaufort Sea ◽  
Gulf Of Alaska ◽  
Sea Surface ◽  
Early Winter ◽  
The North ◽  
The North China Plain ◽  
Haze Pollution ◽  
The Bering Sea

Abstract. Recently, early winter haze pollution in the North China Plain has been serious and disastrous, dramatically damaging human health and the social economy. In this study, we emphasized the close connection between the number of haze days in early winter in the North China Plain and the September–October sea ice in the west of the Beaufort Sea (R=0.51) via both observational analyses and numerical experiments. Due to efficient radiative cooling, the responses of atmospheric circulations partially manifested as reductions of surface wind speed over the Beaufort Sea and Gulf of Alaska, resulting in a warmer sea surface in the subsequent November. The sea surface temperature anomalies over the Bering Sea and Gulf of Alaska acted as a bridge. The warmer sea surface efficiently heated the above air and led to suitable atmospheric backgrounds to enhance the potential of haze weather (e.g., a weaker East Asian jet stream and a Rossby wave-like train propagated from North China and the Sea of Japan, through the Bering Sea and Gulf of Alaska, to the Cordillera Mountains). Near the surface, the weakening sea level pressure gradient stimulated anomalous southerlies over the coastal area of China and brought about a calm and moist environment for haze formation. The thermal inversion was also enhanced to restrict the downward transportation of clear and dry upper air. Thus, the horizontal and vertical dispersion were both limited, and the fine particles were apt to accumulate and cause haze pollution.

scholarly journals Response of Early Winter Haze Days in the North China Plain to Autumn Beaufort Sea Ice

2018 ◽  
Author(s):  
Zhicong Yin ◽  
Yuyan Li ◽  
Huijun Wang
Keyword(s):  
North China Plain ◽  
North China ◽  
Beaufort Sea ◽  
Gulf Of Alaska ◽  
Sea Surface ◽  
Early Winter ◽  
The North ◽  
The North China Plain ◽  
Haze Pollution ◽  
The Bering Sea

Abstract. Recently, early winter haze pollution in the North China Plain has been serious and disastrous, dramatically damaging human health and the social economy. In this study, we emphasized the close connection between early winter haze days in the North China Plain and the September-October sea ice in the west of the Beaufort Sea (R = 0.51). Due to efficient radiative cooling, the responses of atmospheric circulations partially manifested as reductions of surface wind speed over the Beaufort Sea and Gulf of Alaska, resulting in a warmer sea surface in the subsequent November. The sea surface temperature anomalies over the Bering Sea and Gulf of Alaska acted as a bridge. The warmer sea surface efficiently heated the above air and led to suitable atmospheric backgrounds to enhance the potential of haze weather (e.g., a weaker East Asia jet stream and a Rossby wave-like train propagated from North China and the Japan Sea, through the Bering Sea and Gulf of Alaska, to the Cordillera Mountains). Near the surface, the weakening sea level pressure gradient stimulated anomalous southerlies over the coastal area of China and brought about a calm and moist environment for haze formation. The thermal inversion was also enhanced to restrict the underswing of clear and dry upper air. Thus, the horizontal and vertical dispersion were both limited, and the fine particles were apt to accumulate and cause haze pollution.

Possible Relationship between the Chukchi Sea Ice in the Early Winter and the February Haze Pollution in the North China Plain

2019 ◽  
Vol 32 (16) ◽  
pp. 5179-5190 ◽  
Author(s):  
Zhicong Yin ◽  
Huijun Wang ◽  
Xiaohui Ma
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
North China Plain ◽  
North China ◽  
Chukchi Sea ◽  
Early Winter ◽  
Atmospheric Circulations ◽  
The North ◽  
The North China Plain ◽  
Haze Pollution

AbstractHaze pollution is among the most serious disasters in the North China Plain, dramatically damaging human health and the social economy. The frequency of haze events in February typically varies from the number of haze days in the winter. To improve the understanding of haze pollution in February, this study not only showed the large-scale atmospheric circulations associated with the variation in the haze, but also analyzed its connection with Arctic sea ice. The observational and large ensemble model results both illustrated that the preceding increase in the early-winter Chukchi Sea ice might intensify the February haze pollution. The accumulated sea ice over the Chukchi Sea resulted in a steeper meridional sea surface temperature gradient and a significant and persistent westerly thermal wind. In February, the responsive pattern in the atmosphere developed into a Rossby wave–like pattern, linking the Chukchi Sea ice and the February haze pollution. Modulating by the induced large-scale atmospheric circulations, the horizontal and vertical atmospheric ventilation conditions and the hygroscopic growth conditions enhanced the frequency of haze pollution events.

scholarly journals Melting of Perennial Sea Ice in the Beaufort Sea Enhanced Its Impacts on Early-Winter Haze Pollution in North China after the Mid-1990s

2020 ◽  
Vol 33 (12) ◽  
pp. 5061-5080 ◽  
Author(s):  
Yuyan Li ◽  
Zhicong Yin
Keyword(s):  
Sea Ice ◽  
North China ◽  
Beaufort Sea ◽  
Gulf Of Alaska ◽  
Ice Cover ◽  
Sea Surface ◽  
Haze Pollution ◽  
Sea Surface Temperature Anomalies ◽  
Haze Days ◽  
Perennial Ice

AbstractIn recent years, haze pollution has become the most concerning environmental issue in China due to its tremendous negative effects. In this study, we focus on the enhanced responses of December–January haze days in North China to September–October sea ice in the Beaufort Sea during 1998–2015. Via both observation and numerical approaches, compared with an earlier period (1980–97), the sea ice concentration in the Beaufort Sea presented large variability during 1998–2015. During 1980–97, the Beaufort Sea was mainly covered by perennial ice, and the ablation and freezing of sea ice mainly occurred at the south edge of the Beaufort Sea. Thus, heavy sea ice in autumn induced negative sea surface temperature anomalies across the Gulf of Alaska in November. However, the colder sea surface in the Gulf of Alaska only induced a weak influence on the haze-associated atmospheric circulations. In contrast, during 1998–2015, a drastic change in sea ice existed near the center of the Arctic Ocean, due to the massive melting of multiyear sea ice in the western Beaufort Sea. The perennial ice cover in the western Beaufort Sea was replaced by seasonal ice. The broader sea ice cover resulted in positive sea surface temperature anomalies in the following November. Then, suitable atmospheric backgrounds were induced for haze pollution in December and January. Simultaneously, the response of the number of haze days over North China to sea ice cover increased. These findings were verified by the CESM-LE simulations and aided in deepening the understanding of the cause of haze pollution.

scholarly journals Aerosol optical depth thresholds as a tool to assess diffuse radiation fertilization of the land carbon uptake in China

2017 ◽  
Vol 17 (2) ◽  
pp. 1329-1342 ◽  
Author(s):  
Xu Yue ◽  
Nadine Unger
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
North China Plain ◽  
North China ◽  
Carbon Uptake ◽  
The North ◽  
The North China Plain ◽  
Haze Pollution ◽  
Aerosol Pollution ◽  
Sky Conditions

Abstract. China suffers from frequent haze pollution episodes that alter the surface solar radiation and influence regional carbon uptake by the land biosphere. Here, we apply combined vegetation and radiation modeling and multiple observational datasets to assess the radiative effects of aerosol pollution in China on the regional land carbon uptake for the 2009–2011 period. First, we assess the inherent sensitivity of China's land biosphere to aerosol pollution by defining and calculating two thresholds of aerosol optical depth (AOD) at 550 nm, (i) AODt1, resulting in the maximum net primary productivity (NPP), and (ii) AODt2, such that if local AOD < AODt2, the aerosol diffuse fertilization effect (DFE) always promotes local NPP compared with aerosol-free conditions. Then, we apply the thresholds, satellite data, and interactive vegetation modeling to estimate current impacts of aerosol pollution on land ecosystems. In the northeast, observed AOD is 55 % lower than AODt1, indicating a strong aerosol DFE on local NPP. In the southeastern coastal regions, observed AOD is close to AODt1, suggesting that regional NPP is promoted by the current level of aerosol loading, but that further increases in AOD in this region will weaken the fertilization effects. The North China Plain experiences limited enhancement of NPP by aerosols because observed AOD is 77 % higher than AODt1 but 14 % lower than AODt2. Aerosols always inhibit regional NPP in the southwest because of the persistent high cloud coverage that already substantially reduces the total light availability there. Under clear-sky conditions, simulated NPP shows widespread increases of 20–60 % (35.0 ± 0.9 % on average) by aerosols. Under all-sky conditions, aerosol pollution has spatially contrasting opposite sign effects on NPP from −3 % to +6 % (1.6 ± 0.5 % on average), depending on the local AOD relative to the regional thresholds. Stringent aerosol pollution reductions motivated by public health concerns, especially in the North China Plain and the southwest, will help protect land ecosystem functioning in China and mitigate long-term global warming.

scholarly journals Aerosol–radiation feedback deteriorates the wintertime haze in the North China Plain

2019 ◽  
Vol 19 (13) ◽  
pp. 8703-8719 ◽  
Author(s):  
Jiarui Wu ◽  
Naifang Bei ◽  
Bo Hu ◽  
Suixin Liu ◽  
Meng Zhou ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Air Pollutants ◽  
North China Plain ◽  
North China ◽  
Near Surface ◽  
The North ◽  
The North China Plain ◽  
Incoming Solar Radiation ◽  
Haze Pollution ◽  
Pm2.5 Concentration

Abstract. Atmospheric aerosols scatter or absorb a fraction of the incoming solar radiation to cool or warm the atmosphere, decreasing surface temperature and altering atmospheric stability to further affect the dispersion of air pollutants in the planetary boundary layer (PBL). In the present study, simulations during a persistent and heavy haze pollution episode from 5 December 2015 to 4 January 2016 in the North China Plain (NCP) were performed using the Weather Research and Forecasting model with Chemistry (WRF-Chem) to comprehensively quantify contributions of aerosol shortwave radiative feedback (ARF) to near-surface (around 15 m above the ground surface) PM2.5 mass concentrations. The WRF-Chem model generally performs well in simulating the temporal variations and spatial distributions of air pollutants concentrations compared to observations at ambient monitoring sites in the NCP, and the simulated diurnal variations of aerosol species are also consistent with the measurements in Beijing. Additionally, the model simulates the aerosol radiative properties, the downward shortwave flux, and the PBL height against observations in the NCP well. During the episode, ARF deteriorates the haze pollution, increasing the near-surface PM2.5 concentrations in the NCP by 10.2 µg m−3 or with a contribution of 7.8 % on average. Sensitivity studies have revealed that high loadings of PM2.5 attenuate the incoming solar radiation reaching the surface to cool the low-level atmosphere, suppressing the development of the PBL, decreasing the surface wind speed, further hindering the PM2.5 dispersion, and consequently exacerbating the haze pollution in the NCP. Furthermore, when the near-surface PM2.5 mass concentration increases from around 50 to several hundred µg m−3, ARF contributes to the near-surface PM2.5 by more than 20 % during daytime in the NCP, substantially aggravating the heavy haze formation. However, when the near-surface PM2.5 concentration is less than around 50 µg m−3, ARF generally reduces the near-surface PM2.5 concentration due to the consequent perturbation of atmospheric dynamic fields.

scholarly journals Aerosol chemistry and particle growth events at an urban downwind site in the North China Plain

2018 ◽  
Author(s):  
Yingjie Zhang ◽  
Wei Du ◽  
Yuying Wang ◽  
Qingqing Wang ◽  
Haofei Wang ◽  
...  
Keyword(s):  
Growth Rates ◽  
North China Plain ◽  
North China ◽  
Particle Growth ◽  
Early Morning ◽  
Scanning Mobility Particle Sizer ◽  
Average Mass ◽  
The North ◽  
The North China Plain ◽  
Haze Pollution

Abstract. The North China Plain (NCP) has experienced frequent severe haze pollution events in recent years. While extensive measurements have been made in megacities, aerosol sources, processes, and particle growth at urban downwind sites remain less understood. Here, an Aerosol Chemical Speciation Monitor and a Scanning Mobility Particle Sizer, along with a suite of collocated instruments, were deployed at the downwind site of Xingtai, a highly polluted city in the NCP, for real-time measurements of submicron aerosol (PM1) species and particle number size distributions during May and June 2016. The average mass concentration of PM1 was 30.5 (±19.4) μg m−3, which is significantly lower than that during wintertime. Organic aerosols (OA) constituted the major fraction of PM1 (38 %) followed by sulfate (25 %) and nitrate (14 %). Positive matrix factorization with the Multilinear Engine version 2 showed that oxygenated OA (OOA) was the dominant species in OA throughout the study, on average accounting for 78 % of OA, while traffic and cooking emissions both accounted for 11 % of OA. Our results highlight that aerosol particles at the urban downwind site were highly aged and mainly from secondary formation. However, the diurnal cycle also illustrated the substantial influence of urban emissions on downwind sites, which are characterized by similar pronounced early morning peaks for most aerosol species. New particle formation and growth events were also frequently observed (58 % of the time) on both clean and polluted days. Particle growth rates varying from 1.2 to 4.9 nm h−1 were positively related to the condensation sink during periods with high OOA contributions and also to sulfate concentrations during relatively clean periods. Our results showed that sulfate and OOA played important roles in particle growth during clean periods, while OOA was more important than sulfate during polluted events. Further analyses showed that particle growth rates have no clear dependence on air mass trajectories.

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