Impact of Arctic Oscillation anomalies on winter PM_2.5 in China via a numerical simulation

The impact of Arctic Oscillation (AO) anomalies on winter PM_2.5 variability in China was investigated using a numerical modeling system (WRF-CUACE). The model results showed that the influence of AO anomalies on winter PM_2.5 concentration was mainly concentrated in eastern China, especially in Central China (CEN), Beijing-Tianjin-Hebei (BTH), the Yangtze River Delta (YRD), and Pearl River Delta (PRD) and was mostly consistent with the conclusions of a previous analysis using haze data. Winter PM_2.5 concentrations in CEN and BTH increased under abnormally high AO and decreased under abnormally low AO due to the subsequent changes in specific meteorological conditions, such as temperature, wind speed, and boundary layer height. Winter PM_2.5 decreased in the YRD and PRD in both abnormally high and low AO years due to more favorable vertical transport conditions and regional transport capacity compared with those of other regions. In addition to meteorological factors, AO anomalies also impacted PM_2.5 depositions in winter, with more apparent effects in southern China. It is found that AO had a larger impact on dry deposition than on wet deposition, and dry deposition was a dominant factor affecting PM_2.5 concentrations in CEN.