Preprints
https://doi.org/10.5194/acp-2021-603
https://doi.org/10.5194/acp-2021-603

  12 Nov 2021

12 Nov 2021

Review status: this preprint is currently under review for the journal ACP.

The impact of large-scale circulation on daily fine particulate matter (PM2.5) over major populated regions of China in winter

Zixuan Jia1, Ruth Doherty1, Carlos Ordóñez2, Chaofan Li3,6, Oliver Wild4, Shipra Jain1, and Xiao Tang5 Zixuan Jia et al.
  • 1School of GeoSciences, University of Edinburgh, Edinburgh, UK
  • 2Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Madrid, Spain
  • 3Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
  • 4Lancaster Environment Centre, Lancaster University, Lancaster, UK
  • 5LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
  • 6College of Earth and Planetary Sciences, University of the Chinese Academy of Sciences, Beijing, China

Abstract. The influence of large-scale circulation on daily PM2.5 variability through its direct effect on key regional meteorological variables is examined over three major populated regions of China: Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD). In BTH, a shallow East Asian trough curbs northerly cold and dry air from the Siberian High, enhancing PM2.5 pollution levels. Weak southerly winds in eastern and southern China, associated with a weakened Siberian High, suppress horizontal dispersion, contributing to air pollution accumulation over YRD. In PRD, weak southerly winds and precipitation deficits over southern China are conducive to high PM2.5 pollution levels. To account for these dominant large-scale circulation – PM2.5 relationships, we propose three new circulation-based indices for predicting different levels of air pollution based on regional PM2.5 concentrations in each region: a 500 hPa geopotential height-based index for BTH, a sea level pressure-based index for YRD and an 850 hPa meridional wind-based index for PRD. These three indices can effectively distinguish clean days from heavily polluted days in these regions, assuming variation is solely due to meteorology. We also find that including the most important regional meteorological variable in each region improves the performance of the circulation-based indices in predicting daily PM2.5 concentrations on the regional scale. These results are beneficial to understanding and forecasting the occurrence of heavily polluted PM2.5 days in BTH, YRD and PRD from a large-scale perspective.

Zixuan Jia et al.

Status: open (until 24 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Zixuan Jia et al.

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Short summary
This study investigates the modulation of daily PM2.5 over three major populated regions in China by regional meteorology and large-scale circulation during winter. These results demonstrate the benefits of considering the large-scale circulation for air quality studies. The novel circulation indices proposed here can explain a considerable fraction of the day-to-day variability of PM2.5 and can be combined with regional meteorology to improve our capability to predict the variability of PM2.5.
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