Asymmetrical Linkages Between Multifrequency Atmospheric Waves and Variations in Winter PM2.5 Concentrations in Northern China During 2013–2019

Abstract

AbstractAtmospheric waves have a broad spectrum of momentum at various frequencies and link to the PM2.5 concentrations in northern China. We show that the meaningful circulations depended on the wave frequency and the rank of the PM2.5 concentrations. The winter 2013–2019 PM2.5 had different correlations with the subseasonal 850 hPa height anomalies at low (>30 days), intermediate (10–30 days), and high (<10 days) frequencies. The low‐frequency waves increased PM2.5 concentrations by lowering the height over Eurasia and raising the height over the North Atlantic. The first two singular value decomposition principal patterns at the low‐frequency were alike Wavenumber 3 and 4 circulations, respectively. The two patterns accounted for the majority of the background variations of winter PM2.5 in China. The intermediate‐frequency waves increased PM2.5 concentrations via an anomalous dipole pattern over East Asia with a positive polarity over Japan and a negative polarity over Mongolia. The positive polarity is indicative of persistent haze episodes. The high‐frequency waves showed a small dipole correlation pattern with PM2.5, but they barely accounted for high PM2.5 concentrations. The high‐frequency waves traveled quickly. They raised or lowered PM2.5 concentrations in a short time, preventing particulate accumulations. The anomalous heights at the low‐ and intermediate‐frequency for the PM2.5 concentrations >90th showed a few characteristics consistent with the circulation anomalies proposed in previous climate studies with monthly mean data. Synergic effects of the waves at different frequencies result in the observed PM2.5 variations.