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- Title
Measurement report: Nocturnal subsidence behind the cold front enhances surface particulate matter in the plain regions: observation from the mobile multi-lidar system.
- Authors
Yiming Wang; Haolin Wang; Yujie Qin; Xinqi Xu; Guowen He; Nanxi Liu; Shengjie Miao; Xiao Lu; Haichao Wang; Shaojia Fan
- Abstract
A multi-lidar system, mounted in vehicle to monitor the profiles of temperature, wind and particle optical properties, was utilized to investigate the winter fine particulate matter (PM2.5) pollution for a vertical perspective, in four cities in China in winter 2018. We observed the enhancement of surface nocturnal PM2.5 in two typical plain cities (Changzhou and Wangdu), which was attributed to the subsidence of PM2.5 transported from upstream polluted areas, with the wind turning north and downdrafts dominating. Combining with the observed surface PM2.5, the reanalysis meteorological data, and the GEOS-Chem model simulation, we revealed the Transport-Nocturnal PM2.5 Enhancement by Subsidence (T-NPES) events occurred frequently in the two cities, with percentages of 12.2 % and 18.0 %, respectively during Dec. 2018–Feb. 2019. Furthermore, the GEOS-Chem model simulation further confirmed that the ubiquity of winter T-NPES events in a large scale including North China Plain and Yangtze River Delta. Process analysis revealed that the subsidence was closely correlated with the southeasterly movement of the high-pressure system and the passage of the cold front, resulting in the increase of temperature aloft, a stronger inversion layer, and further PM2.5 accumulation in the atmospheric boundary layer. Thus, a conceptual model of the T-NPES events was proposed to highlight this surface PM2.5 enhancement mechanism in these plain regions. However, it was not applicable to the two cities in basin region (Xi’an and Chengdu), due to the obstruction of the weather system movement by the mountains surrounding the basin.
- Subjects
XI'AN Shi (China); CHENGDU (China); FRONTS (Meteorology); ATMOSPHERIC boundary layer; PARTICULATE matter; LAND subsidence; CITIES &; towns; ALLUVIAL plains
- Publication
Atmospheric Chemistry & Physics Discussions, 2023, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/egusphere-2023-2178