Warming of mid-latitude North Atlantic Sea surface temperature strengthens the daily variability of winter PM2.5 in eastern China

Climate factors, in addition to human activities, are acknowledged to exert a notable influence on the synoptic PM2.5 variations over eastern China in extensive case studies. Based on observed daily PM2.5 concentrations data, this study reveals the enhanced daily variability (DV) of PM2.5 concentrations over eastern China and identifies its association with mid-latitude sea surface temperature anomalies over the North Atlantic. The dominant daily mode of PM2.5 concentrations identified through empirical orthogonal function analysis accounts for 43.75% of the total variance, with its DV experienced a significant enhancement from 1979 to 2019. The identified enhancement is attributed to the intensified wave train propagation along the mid-latitudes on a time scale of 10–30 d. The eastward propagation of the identified wave train can expose eastern China to recurrent influences of cyclonic and anticyclonic anomalies, resulting in an initial increase and subsequent decrease in PM2.5 concentrations. Statistical analysis and dynamic diagnostics show that the warming of the mid-latitude North Atlantic Ocean enhances the wave train at its source through the local energy exchange, and ultimately leads to an increased DV of PM2.5 concentrations.