Impact of crop field burning and mountains on heavy haze in the North China Plain: A case study

Abstract

<p><strong>Abstract.</strong> Crop field burning (CFB) has important effects on air pollution in China, but it is seldom quantified and reported in a regional scale, which is of great importance for the control strategies of CFB in China, especially in the North China Plain (NCP). With the provincial statistical data and open crop fires captured by satellite (MODIS), we extracted a detailed emission inventory of CFB during a heavy haze event from 6th to 12th October 2014. A regional dynamical and chemical model (WRF-Chem) was applied to investigate the impact of CFB on air pollution in NCP. The model simulations were compared with the in situ measurements of PM<sub>2.5</sub> (particular matter with radius less than 2.5 μm) concentrations. The model evaluation shows that the correlation coefficients (R) between measured and calculated values exceeds 0.80 and absolute normalized mean bias (NMB) is no more than 14 %. In addition, the simulated meteorological parameters such as winds and planetary boundary layer height (PBLH) are also in good agreement with observations. The model was intensive used to study (1) the impacts of CFB and (2) the effect of mountains on regional air quality. The results show that the CFB occurred in southern NCP (SNCP) had significant effect on PM<sub>2.5</sub> concentrations locally, causing a maximum of 35 % PM<sub>2.5</sub> increase in SNCP. Because of south wind condition, the CFB pollution plume is subjective a long transport to northern NCP (NNCP-with several mega cities, including Beijing of the capital city in China), where there are no significant CFB occurrences, causing a maximum of 32 % PM<sub>2.5</sub> increase in NNCP. As a result, the heavy haze in Beijing is enhanced by the CFB occurred in SNCP. Further more, there are two major mountains located in the western and northern NCP. Under the south wind condition, these mountains play important roles in enhancing the PM<sub>2.5</sub> pollution in NNCP through the blocking and guiding effects. This study suggests that the PM<sub>2.5</sub> emissions in SNCP region should be significantly limited in order to reduce the occurrences of heavy haze events in NNCP region, including the Beijing City.</p>

Impact of Climate Change on Siberian High and Wintertime Air Pollution in China in Past Two Decades

“…Figure shows that there are mountains in the northern and western NCP. When the northerly winds are weak and the southerly winds are dominated, air pollutants accumulate at the foothill due to the northward regional transport, producing heavy air pollution in the NCP (Long et al, ). Therefore, if the climate change induces the variability of the SiH and the prevailing winds in the NCP, it would produce essential impacts on air pollution in the region.…”

“…In the past, more attentions have been paid to the widespread, persistent and frequent haze events during wintertime in the NCP. Previous studies find out that high emission and stable weather patterns play important roles in causing wintertime severe haze events in China (Chang et al, ; Gao et al, ; He et al, ; Jia et al, ; Long et al, ; Tie et al, ; Wang et al, ; Zhang et al, ). Secondary aerosol formation also contributes to severe haze events (Huang et al, ), because initial aerosol nucleation and subsequent continuous growth play significant roles in developing high PM 2.5 mass concentrations during severe haze episodes (Guo et al, ).…”

A Modeling Study of the Impact of Crop Residue Burning on PM2.5 Concentration in Beijing and Tianjin during a Severe Autumn Haze Event

“…In China, agricultural fires mostly occurred in central and north China in early/late June and October. In recent years, crop residue burning often induced serious air pollution in east China and drew increasing attention from public and scientific community (Yang et al, 2008;Li et al, 2010;Tao et al, 2013;Mukai et al, 2014;Long et al, 2016;Yao et al, 2016). A detailed agricultural open fire emission inventory over China with a spatial resolution of 1 km and temporal resolution of 10 days was developed by Huang et al (2012), with the estimated annual emission of PM 2.5 being 0.27 Tg yr -1 .…”

Understanding Variability of Haze in Eastern China

“…In addition to the large spatial dispersion of aerosol pollution, there is also significant temporal variation of aerosol pollution during a short period (days to weeks) in eastern China [9][10][11][12][13]. The focus of this study is to better understand the causes of this short-term temporal variability of aerosol pollution, which has very important implication in haze pollution control in the region.…”