Mechanism for the formation of the January 2013 heavy haze pollution episode over central and eastern China

2013 ◽  
Vol 57 (1) ◽  
pp. 14-25 ◽  
Author(s):  
YueSi Wang ◽  
Li Yao ◽  
LiLi Wang ◽  
ZiRui Liu ◽  
DongSheng Ji ◽  
...  
Keyword(s):  
Eastern China ◽  
Pollution Episode ◽  
Haze Pollution

scholarly journals Impacts of black carbon on the formation of advection-radiation fog during a haze pollution episode in eastern China

2019 ◽  
Author(s):  
Qiuji Ding ◽  
Jianning Sun ◽  
Xin Huang ◽  
Aijun Ding ◽  
Jun Zou ◽  
...  
Keyword(s):  
Black Carbon ◽  
Eastern China ◽  
Vertical Mixing ◽  
Radiation Fog ◽  
Haze Event ◽  
Pollution Episode ◽  
Haze Pollution ◽  
Bc Aerosols ◽  
The Yrd ◽  
The Impact

Abstract. Aerosols can not only participate in fog formation by acting as condensation nuclei of droplets but also modify the meteorological conditions such as air temperature and moisture, planetary boundary layer height (PBLH) and regional circulation during haze event. The impact of aerosols on fog formation, yet to be revealed, can be critical in understanding and predicting of fog-haze event. In this study, we used the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate a heavy fog event during a multiday intense haze pollution episode in early December 2013 in the Yangtze River Delta (YRD) region in eastern China. Using the WRF-Chem model, we conducted four parallel numerical experiments to evaluate the roles of aerosol-radiation interaction (ARI), aerosol-cloud interaction (ACI), black carbon (BC) and none BC (non-BC) aerosols in the formation and maintenance of the heavy fog event. Only when the aerosols' feedback processes are considered can the model well capture the haze pollution and the fog event. We find that the ARI dominates this fog-haze episode while the effects of ACI are negligible. Our analyses shows that BC plays a more important role in fog formation than non-BC aerosols. The dome effect of BC leads to an increase of air moisture over the sea by reducing PBLH and weakening vertical mixing, thereby confining more water vapor in the near-surface layer. The strengthened daytime onshore flow by a cyclonic wind anomaly, induced by contrast temperature perturbation over land and sea, transports moister air to the YRD region, where the suppressed PBLH and weakened daytime vertical mixing maintain the high moisture level. Then the heave fog forms due to the surface cooling at night in this region. This study highlights the importance of anthropogenic emissions in the formation of advection-radiation fog in the polluted coastal areas.

scholarly journals Impacts of black carbon on the formation of advection–radiation fog during a haze pollution episode in eastern China

2019 ◽  
Vol 19 (11) ◽  
pp. 7759-7774 ◽  
Author(s):  
Qiuji Ding ◽  
Jianning Sun ◽  
Xin Huang ◽  
Aijun Ding ◽  
Jun Zou ◽  
...  
Keyword(s):  
Black Carbon ◽  
Eastern China ◽  
Vertical Mixing ◽  
Radiation Fog ◽  
Near Surface ◽  
Pollution Episode ◽  
Haze Pollution ◽  
Bc Aerosols ◽  
The Yrd ◽  
The Impact

Abstract. Aerosols can not only participate in fog formation by acting as condensation nuclei of droplets but also modify the meteorological conditions such as air temperature and moisture, planetary boundary layer height (PBLH) and regional circulation during haze events. The impact of aerosols on fog formation, yet to be revealed, can be critical in understanding and predicting fog–haze events. In this study, we used the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate a heavy fog event during a multiday intense haze pollution episode in early December 2013 in the Yangtze River Delta (YRD) region in eastern China. Using the WRF-Chem model, we conducted four parallel numerical experiments to evaluate the roles of aerosol–radiation interaction (ARI), aerosol–cloud interaction (ACI), black carbon (BC) and non-BC aerosols in the formation and maintenance of the heavy fog event. We find that only when the aerosols' feedback processes are considered can the model capture the haze pollution and the fog event well. And the effects of ARI during the fog–haze episode in early December 2013 played a dominant role, while the effects of ACI were negligible. Furthermore, our analyses show that BC was more important in inducing fog formation in the YRD region on 7 December than non-BC aerosols. The dome effect of BC leads to an increase in air moisture over the sea by reducing PBLH and weakening vertical mixing, thereby confining more water vapor to the near-surface layer. The strengthened daytime onshore flow by a cyclonic wind anomaly, induced by contrast temperature perturbation over land and sea, transported moister air to the YRD region, where the suppressed PBLH and weakened daytime vertical mixing maintained the high moisture level. Then heavy fog formed due to the surface cooling at night. This study highlights the importance of anthropogenic emissions in the formation of advection–radiation fog in the polluted coastal areas.

scholarly journals Transport, mixing and feedback of dust, biomass burning and anthropogenic pollutants in eastern Asia: a case study

2018 ◽  
Vol 18 (22) ◽  
pp. 16345-16361 ◽  
Author(s):  
Derong Zhou ◽  
Ke Ding ◽  
Xin Huang ◽  
Lixia Liu ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Biomass Burning ◽  
Southern China ◽  
Eastern China ◽  
Measurement Data ◽  
Lower Troposphere ◽  
Climate Impacts ◽  
Eastern Asia ◽  
Pollution Episode ◽  
The Yrd

Abstract. Anthropogenic fossil fuel (FF) combustion, biomass burning (BB) and desert dust are the main sources of air pollutants around the globe but are particularly intensive and important for air quality in Asia in spring. In this study, we investigate the vertical distribution, transport characteristics, source contribution and meteorological feedback of these aerosols in a unique pollution episode that occurred in eastern Asia based on various measurement data and modeling methods. In this episode, the Yangtze River Delta (YRD) in eastern China experienced persistent air pollution, dramatically changing from secondary fine particulate pollution to dust pollution in late March 2015. The Eulerian and Lagrangian models were conducted to investigate the vertical structure, transport characteristics and mechanisms of the multi-scale, multisource and multiday air pollution episode. The regional polluted continental aerosols mainly accumulated near the surface, mixed with dust aerosol downwash from the upper planetary boundary layer (PBL) and middle–lower troposphere (MLT), and further transported by large-scale cold fronts and warm conveyor belts. BB smoke from Southeast Asia was transported by westerlies around the altitude of 3 km from southern China, was further mixed with dust and FF aerosols in eastern China and experienced long-range transport over the Pacific. These pollutants could all be transported to the YRD region and cause a structure of multilayer pollution there. These pollutants could also cause significant feedback with MLT meteorology and then enhance local anthropogenic pollution. This study highlights the importance of intensive vertical measurement in eastern China and the downwind Pacific Ocean and raises the need for quantitative understanding of environmental and climate impacts of these pollution sources.

scholarly journals Long-term trends and drivers of aerosol pH in eastern China

2021 ◽  
Author(s):  
Min Zhou ◽  
Guangjie Zheng ◽  
Hongli Wang ◽  
Liping Qiao ◽  
Shuhui Zhu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Prevention And Control ◽  
Action Plan ◽  
Health Effect ◽  
Eastern China ◽  
Pollution Prevention ◽  
Control Action ◽  
Haze Pollution ◽  
Pollution Prevention And Control ◽  
And Control

Abstract. Aerosol acidity plays a key role in regulating the chemistry and toxicity of atmospheric aerosol particles. The trend of aerosol pH and its drivers are crucial in understanding the multiphase formation pathways of aerosols. Here, we reported the first trend analysis of aerosol pH from 2011 to 2019 in eastern China. The implementation of the Air Pollution Prevention and Control Action Plan leads to −35.8 %, −37.6 %, −9.6 %, −81.0 % and 1.2 % changes of PM2.5, SO42−, NHx, NVCs and NO3− in YRD during this period. Different from the fast changes of aerosol compositions due to the implementation of the Air Pollution Prevention and Control Action Plan, aerosol pH shows a moderate change of −0.24 unit over the 9 years. Besides the multiphase buffer effect, the opposite effects of SO42− and non-volatile cations changes play key roles in determining the moderate pH trend, contributing to a change of +0.38 and −0.35 unit, respectively. Seasonal variations in aerosol pH were mainly driven by the temperature, while the diurnal variations were driven by both temperature and relative humidity. In the future, SO2, NOx and NH3 emissions are expected to be further reduced by 86.9 %, 74.9 % and 41.7 % in 2050 according to the best health effect pollution control scenario (SSP1-26-BHE). The corresponding aerosol pH in eastern China is estimated to increase by ~0.9, resulting in 8 % more NO3− and 35 % less NH4+ partitioning/formation in the aerosol phase, which suggests a largely reduced benefit of NH3 and NOx emission control in mitigating haze pollution in eastern China.

scholarly journals MODIS Cloud Detection Evaluation Using CALIOP over Polluted Eastern China

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 333 ◽  
Author(s):  
Saichun Tan ◽  
Xiao Zhang ◽  
Guangyu Shi
Keyword(s):  
Eastern China ◽  
Cloud Fraction ◽  
Orthogonal Polarization ◽  
Aerosol Layer ◽  
Cloud Detection ◽  
Haze Pollution ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Cloud Optical Thickness ◽  
Moderate Resolution Imaging Spectroradiometer

Haze pollution has frequently occurred in winter over Eastern China in recent years. Over Eastern China, Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection data were compared with the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) for three years (2013–2016) for three kinds of underlying surface types (dark, bright, and water). We found that MODIS and CALIOP agree most of the time (82% on average), but discrepancies occurred at low CALIOP cloud optical thickness (COT < 0.4) and low MODIS cloud top height (CTH < 1.5 km). In spring and summer, the CALIOP cloud fraction was higher by more than 0.1 than MODIS due to MODIS’s incapability of observing clouds with a lower COT. The discrepancy increased significantly with a decrease in MODIS CTH and an increase in aerosol optical depth (AOD, about 2–4 times), and MODIS observed more clouds that were undetected by CALIOP over PM2.5 > 75 μg m−3 regions in autumn and particularly in winter, suggesting that polluted weather over Eastern China may contaminate MODIS cloud detections because MODIS will misclassify a heavy aerosol layer as cloudy under intense haze conditions. Besides aerosols, the high solar zenith angle (SZA) in winter also affects MODIS cloud detection, and the ratio of MODIS cloud pixel numbers to CALIOP cloud-free pixel numbers at a high SZA increased a great deal (about 4–21 times) relative to that at low SZA for the three surfaces. As a result of the effects of aerosol and SZA, MODIS cloud fraction was 0.08 higher than CALIOP, and MODIS CTH was more than 2 km lower than CALIOP CTH in winter. As for the cloud phases and types, the results showed that most of the discrepancies could be attributed to water clouds and low clouds (cumulus and stratocumulus), which is consistent with most of the discrepancies at low MODIS CTH.

scholarly journals Evaluating the performance of two surface layer schemes for the momentum and heat exchange processes during severe haze pollution in Jing-Jin-Ji in eastern China

2018 ◽  
Vol 18 (23) ◽  
pp. 17421-17435 ◽  
Author(s):  
Yue Peng ◽  
Hong Wang ◽  
Yubin Li ◽  
Changwei Liu ◽  
Tianliang Zhao ◽  
...  
Keyword(s):  
Surface Layer ◽  
Roughness Length ◽  
Turbulent Flux ◽  
Eastern China ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Chemical Models ◽  
Atmospheric Stratification ◽  
Haze Pollution ◽  
Thermal Roughness Length

Abstract. The turbulent flux parameterization schemes in the surface layer are crucial for air pollution modeling. There have been some deficiencies in the prediction of air pollutants by atmosphere chemical models, which is closely related to the uncertainties of the momentum and sensible heat fluxes calculated in the surface layer. The differences between two surface layer schemes (Li and MM5 schemes) were discussed, and the performances of two schemes were mainly evaluated based on the observed momentum and sensible heat fluxes during a heavy haze episode in Jing-Jin-Ji in eastern China. The results showed that the aerodynamic roughness length z0m and the thermal roughness length z0h played major roles in the flux calculation. Compared with the Li scheme, ignoring the difference between z0m and z0h in the MM5 scheme induced a great error in the calculation of the sensible heat flux (e.g., the error was 54 % at Gucheng station). Besides the roughness length, the algorithm for the surface turbulent flux as well as the roughness sublayer also resulted in certain errors in the MM5 scheme. In addition, magnitudes of z0m and z0h have significant influence on the two schemes. The large z0m and z0m∕z0h in megacities with a rough surface (e.g., Beijing) resulted in much larger differences of momentum and sensible heat fluxes between Li and MM5, compared with the small z0m and z0m∕z0h in suburban areas with a smooth surface (e.g., Gucheng). The Li scheme could better characterize the evolution of atmospheric stratification than the MM5 scheme in general, especially for the transition stage from unstable to stable atmospheric stratification, corresponding to the PM2.5 accumulation. The biases of momentum and sensible heat fluxes from Li were lower, about 38 % and 43 %, respectively, than those from MM5 during this stage. This study indicates the superiority of the Li scheme in describing regional atmospheric stratification and an improved possibility of severe haze prediction in Jing-Jin-Ji in eastern China by coupling it into atmosphere chemical models.

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