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Environmental Statistics Group
Shixian Zhai Postdoctoral FellowHarvard UniversityPM2.5 and its composition changes in China, 2013-2018: contributions from meteorology and emissionsPM2.5 is a severe air pollution problem in China. Observations of PM2.5 have been available since 2013 from a large network operated by the China National Environmental Monitoring Center (CNEMC). The data show a general 30%–50% decrease in annual mean PM2.5 across China over the 2013–2018 period, averaging at −5.2 μg m−3 a−1. However, there is also a large meteorologically driven interannual variability in PM2.5 that complicates trend attribution. We used a stepwise multiple linear regression (MLR) model to quantify this meteorological contribution to the PM2.5 trends across China. The MLR model correlates the 10 d PM2.5 anomalies to wind speed, precipitation, relative humidity, temperature, and 850 hPa meridional wind velocity (V850). The meteorology-corrected PM2.5 trends after removal of the MLR meteorological contribution can be viewed as being driven by trends in anthropogenic emissions. The mean PM2.5 decrease across China is −4.6 μg m−3 a−1 in the meteorology-corrected data, 12 % weaker than in the original data, meaning that 12 % of the PM2.5decrease in the original data is attributable to meteorology. We then used an updated GEOS-Chem model driven by yearly emissions from the Multi-resolution Emission Inventory for China (MEIC) to interpret trends observed in the nationwide network as well as in PM2.5 composition data from a number of sites. Event Url https://ems.sph.harvard.edu/MasterCalendar/EventDetails.aspx?data=hHr80o3M7J7kc1O9d0SEA3RRoqbfCDDnCWOCesqtlCVG8R3EhEb9m8bZYS8NI2s5