Vertical Stratification of Dust and Anthropogenic Aerosols and Their Seasonal Impact on Radiative Forcing in Semi-Arid Northwest China

Aerosol optical properties and radiative forcing critically influence Earth’s climate, particularly in semi-arid regions. This study investigates these properties in Yinchuan, Northwest China, focusing on aerosol optical depth (AOD), single scattering albedo (SSA), Ångström Index, and direct radiative forcing (DRF) using 2023 CE-318 sun photometer data, HYSPLIT trajectory analysis, and the SBDART model. Spring AOD peaks at 0.58 ± 0.15 (500 nm) due to desert dust, with coarse-mode particles dominating, while summer SSA reaches 0.94, driven by fine-mode aerosols. Internal mixing of dust and anthropogenic aerosols significantly alters DRF through enhanced absorption, with spring surface DRF at -101.1 W m⁻² indicating strong cooling and internal mixing increasing atmospheric DRF to 52.2W m⁻².These findings elucidate dust-anthropogenic interactions’ impact on optical properties and radiative forcing, offering critical observations for semi-arid climate research.