基于太阳光度计资料的敦煌地区气溶胶光学特征分析

Analysis of Aerosol Optical Properties in Dunhuang Area Based on CE318 Data

文章基于CE318太阳光度计观测数据,对敦煌市2018—2021年来的气溶胶光学厚度(AOD)、波长指数(α)、浊度系数(β)等进行反演计算,在此基础上对其年变化、季节变化、日变化进行分析。结果表明:(1)与东部沿海地区相比,敦煌地区AOD全年整体偏低,污染情况整体较轻,α年均值为0.2,即大气污染以粗模态的沙尘粒子为主,属于极具代表性的沙尘气溶胶模态,全年大气状况较为清洁。(2)气溶胶特性存在较为明显季节变化特征,AOD在春季(3—5月)最大值达到0.67,夏季呈现下降趋势,到秋季又略有升高,冬季12—次年2月最小,为0.1,并且浊度系数的分布与其正相关。(3)AOD、α、β在一天之内的波动变化也同样存在显著的季节性差异。春季较为明显,日出前数值最低,每日11时达到峰值,之后慢慢回落且趋于稳定;冬季全天变化不大,只是在日出后数据略有升高,这与冬天大气场较为稳定有关,整个变化过程中人类生产活动对其影响较小。敦煌地区的大气气溶胶以自然源为主,受到春、秋两季沙尘暴频发影响,春季尤为明显,秋季次之,这两季气溶胶粒子较大,空气污染状况较为严重。沙尘暴也是影响敦煌地区的气溶胶变化的主要因素。

Based on the observation data of CE318 sun photometer,the aerosol optical depth(AOD),wavelength index(α)and turbidity coefficient(β)in Dunhuang City in the past four years were retrieved and calculated,and their annual,seasonal and diurnal variation characteristics were analyzed.The results showed that:(1)Compared with the eastern coastal area,the AOD in Dunhuang area was lower and the pollution was lighter overall.The annual average value ofαwas 0.2,indicating that the air pollution was mainly composed of coarse dust particles,which was a representative dust aerosol mode and the air condition was relatively clean throughout the year.(2)The aerosol showed obvious seasonal variation characteristics.AOD reached the maximum value of 0.67from March to May in spring,showed a decreasing trend in summer and a slightly increasing trend in autumn,and reached the minimum value of 0.1 from December to February the next year.Meanwhile,the distribution of turbidity coefficient was positively correlated with AOD.(3)There were significant seasonal differences in the daily fluctuation of AOD,αandβ.In spring,the fluctuation was more obvious,with the values of AOD,αandβbeing lowest before sunrise,reaching the peak at 11 o'clock every day,and then slowly falling and tending to be stable.In winter,the daily fluctuation was small and the values only increased slightly after sunrise,which was related to the stability of the atmospheric field in winter,and human production activities had little impact on it.To sum up,the atmospheric aerosols in Dunhuang area were mainly from natural sources,which were affected by frequent sandstorms in spring and autumn,especially in spring.The aerosol particles were larger and air pollutions were more serious in those two seasons.Dust storm was also the main factor affecting the change of aerosol in Dunhuang area.