Temporal coherence in particulate matters in East Asian outflow regions: fingerprints of ENSO, Asian dust and COVID-19

Abstract

Understanding temporal coherence in particulate matter (PM) pollution across East Asian outflow regions is crucial for collaborative efforts in addressing air pollution challenges. In this study, we analyze daily PM exceedance patterns using ground-based measurements over the past two decades, focusing on the influence of El Niño-Southern Oscillation (ENSO) and Asian dust activity. ENSO-related coherent PM exceedance shows lower occurrence during El Niño compared to La Niña in spring, due to weakened continental outflows and increased precipitation. Temporal distribution of dust-related coherent PM exceedance closely mirrors springtime dust activity in source regions, indicating significant dust emission impact on outflow regions. Furthermore, COVID-19 restrictions likely contributed to decreased PM levels in the spring of 2020. Our findings have implications for climate variability and the assessment of multi-decade model simulations.