[Aerosol Optical Properties over the Ebinur Region]

The key to understanding the transport and deposition process of salt dust to Ebinur Lake involves the quantitative evaluation of the aerosol concentration and characteristics in Jinghe County. Based on the data of the CE-318 sun photometer station in Jinghe County during 2019, the characteristics of the aerosol optical depth (AOD) and Angström exponent (α) were analysed. The results showed that the daily variation of the AOD in Jinghe County was a single peak curve that increased or decreased monotonously in the early/late peak period and peaked at 12:00-14:00, which was opposite to the trend of the α. There were obvious seasonal differences in the aerosol concentration and dominant mode. The seasonal AOD was ranked as:spring (0.403±0.282) > summer (0.222±0.135) > autumn (0.218±0.112), whereas α was ranked as:summer (1.339±0.446) > autumn (1.116±0.278) > spring (0.914±0.269). During the spring, the range of the change in the AOD was more intense, the aerosol particle size was larger than that during the summer and autumn, and the range of the variation in the particle size was larger. There was a negative correlation between the AOD and α. During the spring and summer, the aerosol particle size varied over a wide range, and the composition was more complex. With the decrease of the α, the AOD tended to increase; during the autumn, the dominant aerosol mode (mainly fine particles) stabilized, and the AOD exhibited no obvious change with the α. From spring to autumn, aerosol gradually transited from a coarse to fine mode. Compared with the summer, local aerosols were more sensitive to the changes of the wind speed, wind direction, and relative humidity during the spring. The primary reason for the increase of the AOD during the spring was the main wind direction and the dust input brought by gale weather. Influenced by the soluble salt ions in the dust, the aerosol particles were able to undergo hygroscopic growth, but this was not the main reason for the high AOD. Temperature was not the internal factor for the change in the local aerosols; however, it was directly proportional to the diffusion ability of aerosol particles. Overall, the AOD of Jinghe County was primarily affected by dust aerosols. The increases in the amounts of small particles and aerosol moisture absorption were not the main reasons for the increase of the AOD in this area.