Spatiotemporal features and optical properties of aerosols in the Ili Basin: A CALIPSO-based analysis (2008–2022)

Abstract

Aerosols such as dust exhibit strong light-absorption properties. The Ili Basin (IB) has become an important deposition area for aerosols owing to its distinctive geographic location and the influence of westerly winds. In this study, we investigated the spatiotemporal features and optical properties of aerosols in the IB using Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data from 2008 to 2022. The results indicated that there were six aerosol subtypes in the IB, of which dust and polluted dust (PD) were the dominant aerosol subtypes, accounting for over 83% of the aerosols in this region. The frequency of dust was highest in spring, and that of PD was highest in summer. Spatially, dust occurred primarily in the southwest, central, and eastern regions, whereas PD occurred primarily in the central and northwest regions. Aerosols were mainly distributed below 10 km, peaking at 3–4 km. The height of the dust layer was greater than 4 km in most parts of the IB, with the highest values in the southwest and east. The distribution of the PD layer was lower than that of the dust layer. The extinction coefficients, particulate depolarization ratios, and backscatter coefficients were higher in the eastern part of the IB. This study suggests that future research should focus on the mountainous areas in the southern and eastern parts of the IB to clarify the deposition of absorptive aerosols and their effect on snow ablation.