Spatiotemporal Variability in Aerosol Composition and Radiative Effects Over Central Asia

Abstract

Different aerosol components play critical roles in regulating the regional radiative budget. Despite the climatic importance of aerosol composition, the long‐term evolution and radiative effects of major aerosol components over Central Asia remain insufficiently characterised owing to the sparse spatial coverage of ground‐based observations. Clarifying these patterns is essential for understanding the climatic influence of aerosol composition in arid regions. This study integrates MODIS MAIAC aerosol products, MERRA‐2 reanalysis data and an XGBoost SHAP framework to investigate the contribution evolution and underlying mechanisms of major aerosol components including dust aerosol (Dust), sulphate aerosol (SO 4 ), organic carbon (OC), black carbon (BC) and sea salt (SS) to aerosol optical depth and aerosol radiative forcing efficiency. The results indicate that high values of total aerosol optical depth are primarily concentrated over the Taklimakan Desert and surrounding regions, exhibiting a pronounced gradient increasing from northwest to southeast. Dust and SO 4 consistently represented the dominant contributors to AOD, with a combined contribution generally exceeding 80%. Anthropogenic aerosols including SO 4 , OC and BC show a significant increase after 1990, whereas sea salt aerosol contributions remain relatively small and stable. Radiative effect analysis showed that although SS contributed little to total AOD, SS exhibited greater importance at the TOA and within the atmosphere, whereas BC and OC played more prominent roles at the surface. This contrast may be associated with the strong scattering capacity and hygroscopic growth of SS, as well as the absorptive properties and mixing states of carbonaceous aerosols. These findings elucidate the hierarchical regulatory role of major aerosol components on the regional radiative budget in Central Asia and provide a scientific basis for regional climate modelling and policy formulation.