The distribution and trends of fog and haze in the North China Plain over the past 30 years
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In this paper, the authors examined the horizontal distribution and decadal trends of low visibility, haze and fog events in the North China Plain (NCP) during the past 30 years.Abstract:
. Frequent low visibility, haze and fog events were found in the North China Plain (NCP). Data throughout the NCP during the past 30 years were examined to determine the horizontal distribution and decadal trends of low visibility, haze and fog events. The impact of meteorological factors such as wind and relative humidity (RH) on those events was investigated. Results reveal distinct distributions of haze and fog days, due to their different formation mechanisms. Low visibility, haze and fog days all display increasing trends of before 1995, a steady stage during the period 1995–2003 and a drastically drop thereafter. All three events occurred most frequently during the heating season. Benefiting from emission control measures, haze and fog both show decreasing trends in winter during the past 3 decades, while summertime haze displays continuous increasing trends. The distribution of wind speed and wind direction as well as the topography within the NCP has determinative impacts on the distribution of haze and fog. Weakened south-easterly winds in the southern part of the NCP have resulted in high pollutant concentrations and frequent haze events along the foot of the Taihang Mountains. The orographically generated boundary layer wind convergence line in the central area of the southern NCP is responsible for the frequent fog events in this region. Wind speed has been decreasing throughout the entire southern NCP, resulting in more stable atmospheric conditions and weaker dispersion abilities, calling for harder efforts to control emissions to prevent haze events. Haze events are strongly influenced by the ambient RH. RH values associated with haze days are evidently increasing, suggesting that an increasing fraction of haze events are caused by the hygroscopic growth of aerosols, rather than simply by high aerosol loadings.read more
Citations
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Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)
TL;DR: The GMTED2010 layer extents (minimum and maximum latitude and longitude) are a result of the coordinate system inherited from the 1-arcsecond SRTM.
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Severe haze in northern China: A synergy of anthropogenic emissions and atmospheric processes.
Zhisheng An,Ru-Jin Huang,Renyi Zhang,Xuexi Tie,Guohui Li,Guohui Li,Junji Cao,Junji Cao,Weijian Zhou,Weijian Zhou,Zhengguo Shi,Zhengguo Shi,Yongming Han,Yongming Han,Zhaolin Gu,Yuemeng Ji,Yuemeng Ji +16 more
TL;DR: It is highlighted that improved understanding of the emission sources, physical/chemical processes during haze evolution, and interactions with meteorological/climatic changes are necessary to unravel the causes, mechanisms, and trends for haze pollution.
Journal ArticleDOI
Fine particulate matter (PM 2.5 ) trends in China, 2013–2018: separating contributions from anthropogenic emissions and meteorology
Shixian Zhai,Daniel J. Jacob,Xuan Wang,Lu Shen,Ke Li,Yuzhong Zhang,Ke Gui,Tianliang Zhao,Hong Liao +8 more
Abstract: Abstract. Fine particulate matter (PM2.5) is a severe air pollution
problem in China. Observations of PM2.5 have been available since 2013
from a large network operated by the China National Environmental Monitoring
Center (CNEMC). The data show a general 30 %–50 % decrease in annual mean
PM2.5 across China over the 2013–2018 period, averaging at −5.2 µg m−3 a−1. Trends in the five megacity cluster regions targeted by
the government for air quality control are -9.3±1.8 µg m−3 a−1 (±95 % confidence interval) for Beijing–Tianjin–Hebei,
-6.1±1.1 µg m−3 a−1 for the Yangtze River Delta, -2.7±0.8 µg m−3 a−1 for the Pearl River Delta, -6.7±1.3 µg m−3 a−1 for the Sichuan Basin, and -6.5±2.5 µg m−3 a−1 for the Fenwei Plain (Xi'an). Concurrent 2013–2018
observations of sulfur dioxide (SO2) and carbon monoxide (CO) show that
the declines in PM2.5 are qualitatively consistent with drastic
controls of emissions from coal combustion. However, there is also a large
meteorologically driven interannual variability in PM2.5 that
complicates trend attribution. We used a stepwise multiple linear regression
(MLR) model to quantify this meteorological contribution to the PM2.5 trends across China. The MLR model correlates the 10 d PM2.5
anomalies to wind speed, precipitation, relative humidity, temperature, and
850 hPa meridional wind velocity (V850). The meteorology-corrected
PM2.5 trends after removal of the MLR meteorological contribution can
be viewed as being driven by trends in anthropogenic emissions. The mean
PM2.5 decrease across China is −4.6 µg m−3 a−1 in the
meteorology-corrected data, 12 % weaker than in the original data, meaning
that 12 % of the PM2.5 decrease in the original data is
attributable to meteorology. The trends in the meteorology-corrected data
for the five megacity clusters are -8.0±1.1 µg m−3 a−1 for Beijing–Tianjin–Hebei (14 % weaker than in the original
data), -6.3±0.9 µg m−3 a−1 for the Yangtze River Delta
(3 % stronger), -2.2±0.5 µg m−3 a−1 for the Pearl River
Delta (19 % weaker), -4.9±0.9 µg m−3 a−1 for
the Sichuan Basin (27 % weaker), and -5.0±1.9 µg m−3 a−1 for the Fenwei Plain (Xi'an; 23 % weaker); 2015–2017 observations of
flattening PM2.5 in the Pearl River Delta and increases in the Fenwei
Plain can be attributed to meteorology rather than to relaxation of emission
controls.
Journal ArticleDOI
Formation, features and controlling strategies of severe haze-fog pollutions in China
Hongbo Fu,Jianmin Chen +1 more
TL;DR: Focused on the core scientific issues of the haze and fog pollution, this paper reviews the main studies conducted in China, especially after 2010, including formation mechanisms, evolution features, and factors contributing to the fog-haze pollutions.
Journal ArticleDOI
Satellite-based mapping of daily high-resolution ground PM 2.5 in China via space-time regression modeling
Qingqing He,Bo Huang +1 more
TL;DR: In this article, a space-time regression model that is an improved geographically and temporally weighted regression (GTWR) with an interior point algorithm (IPA)-based efficient mechanism for selecting optimal parameter values, was developed to estimate a large set of daily PM2.5 concentrations.
References
More filters
Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)
TL;DR: The GMTED2010 layer extents (minimum and maximum latitude and longitude) are a result of the coordinate system inherited from the 1-arcsecond SRTM.
Journal ArticleDOI
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TL;DR: Wang et al. as discussed by the authors evaluated the visibility trends for six major megacities (Beijing, Chengdu, Guangzhou, Shanghai, Shenyang, and Xi'an) in China during 1973-2007 on the basis of the National Climatic Data Center (NCDC) database.
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