艾比湖地区气溶胶光学特性分析

Aerosol Optical Properties over the Ebinur Region

精河县气溶胶光学特性的定量评估是理解艾比湖盐尘传输过程的关键.本文利用2019年精河县CE-318太阳光度计站点观测资料,分析了气溶胶光学厚度(AOD)和Angstrom波长指数(α)的变化特征.结果表明AOD日变化呈单峰曲线,与α呈反向变化特征;气溶胶粒子浓度和主控模态具有明显的季节性差异,与夏、秋季相比,春季AOD较高且变化幅度剧烈,粗粒子气溶胶占主控地位,粒子粒径和变化幅度较大;AOD和α呈负相关关系,从春季到秋季,气溶胶逐渐从粗模态向细模态过渡;与夏季相比,春季局地气溶胶对风速、风向和相对湿度的变化较为敏感;温度不是导致局地气溶胶变化的内在因素,但与气溶胶粒子扩散能力成正比;非采暖期,精河县AOD高值主要受粗粒子为主的沙尘气溶胶的影响,小颗粒的气溶胶的增加以及气溶胶吸湿增长都不是造成该地区AOD增加的主要原因.

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 Angstrom 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 theα.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),whereasαwas 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 andα.During the spring and summer,the aerosol particle size varied over a wide range,and the composition was more complex.With the decrease of theα,the AOD tended to increase;during the autumn,the dominant aerosol mode(mainly fine particles)stabilized,and the AOD exhibited no obvious change with theα.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.