Characteristics of PM2.5 spatial distribution and influencing meteorological conditions in Sichuan Basin, southwestern China

Understanding the mechanisms causing spatial variations of PM2.5 can provide implications of factors influencing air pollution possibilities. In this study, the spatial distribution of PM2.5 concentration was decomposed into various patterns by applying the Empirical Orthogonal Function (EOF) analysis to investigate main PM2.5 mass distribution patterns and corresponding meteorological conditions in the Sichuan Basin, southwestern China. The first five EOF patterns were determined and accounted for 80.5% of the total variance. The first pattern (61.7%) was consistent with the average PM2.5 mass distribution in the study area and was attributed to anthropogenic emissions. The remaining four patterns were ascribed to meteorological conditions and topography. The distribution patterns of the second and third EOFs were mainly caused by horizontal transport of pollutants accompanied by different circulation types. The fourth EOF was influenced by horizontal circulation, vertical movement and topography synthetically. The fifth EOF presented circular distribution of PM2.5 and resulted from convection activities accompanied with subsidence in the perimeter within the basin. This information provides a new perspective to explore the meteorological influence on regional distribution of PM2.5 in the Sichuan Basin, while having implications for refining pollution control strategies on a regional scale.