Large-scale transport of PM2.5 in the lower troposphere during winter cold surges in China

Abstract

A comprehensive investigation using the air quality network and meteorological data of China in 2015 showed that PM2.5 driven by cold surges from the ground level could travel up to 2000 km from northern to southern China within two days. Air pollution is more severe and prominent during the winter in north China due to seasonal variations in energy usage, trade wind movements, and industrial emissions. In February 2015, two cold surges traveling from north China caused a temporary increase in the concentration of PM2.5 in Shanghai. Subsequently, the concentration of PM2.5 in Xiamen increased to a high of 80 µg/m3 , which is double the average PM2.5 concentration in Xiamen during the winter. This finding is a new long-range transport mechanism comparing to the well-established mechanism, with long-range transport more likely to occur in the upper troposphere than at lower levels. These observations were validated by results from the back trajectory analysis and the RAMS- CMAQ model. While wind speed was found to be a major facilitator in transporting PM2.5 from Beijing to Xiamen, more investigation is required to understand the complex relationship between wind speed and PM2.5 and how it moderates air quality in Beijing, Shanghai, and Xiamen.

Joint Governance Regions and Major Prevention Periods of PM2.5 Pollution in China Based on Wavelet Analysis and Concentration-Weighted Trajectory

“…The local control and prevention of pollution mainly focuses on the relocation of heavily polluted enterprises or on regulating cars. However, PM 2.5 pollution does not only come from local emissions, but is also influenced by meteorological conditions, such as wind direction and speed [10]. Local governments cannot mitigate pollution by themselves.…”

Simultaneous Measurements of Chemical Compositions of Fine Particles during Winter Haze Period in Urban Sites in China and Korea

“…In winter, Korea and China are located on the downwind of winter monsoons. Wang et al [12] reported that Southeast China was affected by long-range transported pollutants from Northern China during the cold surges. A similar behavior was also observed in Korea in winter.…”

Investigation of the Air Pollution Event in Beijing-Tianjin-Hebei Region in December 2016 Using WRF-Chem

“…e air pollution is composed of multiple pollutants, which are mainly attributed to power plants, domestic pollutants, industry, and vehicle exhaust [9,[15][16][17]. Meteorological conditions are also important in modulating the distribution of atmospheric pollutants in the BTH [18][19][20][21][22]. Many studies have concluded that high relative humidity is conducive to secondary growth of pollutants, worsening air quality [23][24][25].…”

“…In addition to local emissions, the contribution of regional transport mainly depends on wind direction [19]. Taking Beijing as an example, southerly winds are more likely associated with severe air pollution than other wind directions because a portion of the pollutants and warm humid air can be carried from upwind areas to the city [18,20,23,24,[27][28][29][37][38][39].…”

“…Taking Beijing as an example, southerly winds are more likely associated with severe air pollution than other wind directions because a portion of the pollutants and warm humid air can be carried from upwind areas to the city [18,20,23,24,[27][28][29][37][38][39]. With prevailing northerly winds, pollutants are exported from Beijing to its south [19,38,39]. On the contrary, in order to reduce pollution incidents, the Chinese government urges the BTH region and its neighboring area to adjust the energy structure in the way of closing down factories with high energy consumption and high pollution, promote the modification of desulphurization and denitrification, eliminate backward production capacity, and so on (http://www.hebqg.…”