Abstract
Abstract. The regional transport of air pollutants, controlled by emission sources and meteorological factors, results in a complex source–receptor relationship of air pollution change. Wuhan, a metropolis in the Yangtze River middle basin (YRMB) of central China, experienced heavy air pollution characterized by hourly PM2.5 concentrations reaching 471.1 µg m−3 in January 2016. To investigate the regional transport of PM2.5 over central eastern China (CEC) and the meteorological impact on wintertime air pollution in the YRMB area, observed meteorological and other relevant environmental data from January 2016 were analyzed. Our analysis presented noteworthy cases of heavy PM2.5 pollution in the YRMB area with unique “non-stagnant” meteorological conditions of strong northerly winds, no temperature inversion, and additional unstable structures in the atmospheric boundary layer. This unique set of conditions differed from the stagnant meteorological conditions characterized by near-surface weak winds, air temperature inversion, and stable structure in the boundary layer that are typically observed in heavy air pollution over most regions in China. The regional transport of PM2.5 over CEC aggravated PM2.5 levels, thus creating heavy air pollution in the YRMB area. This demonstrates a source–receptor relationship between the originating air pollution regions in CEC and the receiving YRMB region. Furthermore, a backward trajectory simulation using a Flexible Particle dispersion (FLEXPART) Weather Research and Forecasting (WRF) model to integrate the air pollutant emission inventory over China was used to explore the patterns of regional transport of PM2.5 governed by the strong northerly winds in the cold air activity of the East Asian winter monsoon season. It was estimated that the regional transport of PM2.5 from non-local air pollutant emissions contributes more than 65 % of the PM2.5 concentrations to the heavy air pollution in the YRMB region during the study period, revealing the importance of the regional transport of air pollutants over China as a causative factor of heavy air pollution over the YRMB area.
Highlights
Haze pollution can result in serious environmental problems that adversely influence human health, climate change, and other significant aspects
This study investigated the ambient PM2.5 variations over Wuhan, a typical Yangtze River middle basin (YRMB) area in central China in January 2016, by analyzing the observational data of the environment and meteorology
We did a FLEXPART-Weather Research and Forecasting (WRF) simulation to explore the meteorological processes involved in the regional transport of air pollutants and the regional transport patterns of PM2.5 and how it contributes to heavy air pollution in the YRMB region
Summary
Haze pollution can result in serious environmental problems that adversely influence human health, climate change, and other significant aspects The regional transport of PM2.5 from source regions can deteriorate air quality in the downwind receptor regions, leading to the regional haze pollution observed in a large area over China (Chang et al, 2018; He et al, 2017; Hu et al, 2018; Jiang et al, 2015; Wang et al, 2014). The Yangtze River middle basin (YRMB) covers the lower subbasin of two provinces, Hubei and Hunan, in central China It is geographically surrounded by four major haze pollution regions, the NCP to the north, the YRD to the east, the PRD to the south, and the SCB to the west (Fig. 1a). The regional transport routes of PM2.5 across CEC are governed by meteorological drivers and their contribution to air pollution over the YRMB area are poorly understood, especially in relation to heavy air pollution events. This study selected Wuhan as a representative area within the YRMB for investigating the meteorological changes in air pollution events in January 2016 and assessing the contribution of regional transport of PM2.5 over CEC to heavy air pollution in the YRMB area
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