LAUSR

Aerosol observational data for 2012 obtained from Dunhuang Station of CARE-China (Campaign on Atmospheric Aerosol Research Network of China) were analyzed to achieve in-depth knowledge of aerosol optical properties over Dunhuang region. The results showed that the annual average aerosol optical depth (AOD) at 500 nm was 0.32±0.06, and the Ångström exponent (α) was 0.73 ± 0.27. Aerosol optical properties revealed significant seasonal characteristics. Frequent sandstorms in MAM (March–April–May) resulted in the seasonal maximum AOD, 0.41 ± 0.04, and a relatively smaller α value, 0.44±0.04. The tourism seasons, JJA (June–July–August) and SON (September–October–November) coincide with serious emissions of small anthropogenic aerosols. While in DJF (December–January–February), the composition of the atmosphere was a mixture of dust particles and polluted aerosols released by domestic heating; the average AOD and α were 0.29 ± 0.02 and 0.66 ± 0.17, respectively. Different air masses exhibited different degrees of influence on the aerosol concentration over Dunhuang in different seasons. During MAM, ranges of AOD (0.11–1.18) and α (0.06–0.82) were the largest under the dust influence of northwest-short-distance air mass in the four trajectories. Urban aerosols transported by northwest-short-distance air mass accounted for a very large proportion in JJA and the mixed aerosols observed in SON were mainly conveyed by air masses from the west. In DJF, the similar ranges of AOD and α under the three air mass demonstrated the analogous diffusion effects on regional pollutants over Dunhuang.摘要2012年中国气溶胶综合特性观测网 (CARE-China)敦煌站气溶胶光学特性观测分析结果表明:该地区500nm波段AOD年均值为0.32 ± 0.06, 波长指数(α)年均值为0.73 ± 0.27. 敦煌地区气溶胶光学特性呈现显著季节变化特征. 春季多沙尘天气, AOD达到最大季节均值0.41 ± 0.04, 相应α值较小, 为0.44 ± 0.04; 夏秋两季是旅游旺季, 大量游客涌入及机动车的使用排放大量人为气溶胶粒子; 冬季出现沙尘粒子和家用燃煤取暖排放的细粒子的复合型污染, AOD和α分别为0.29 ± 0.02和0.66 ± 0.17. 不同季节不同气团对该地区气溶胶浓度影响不同. 春季, 西北短程气团裹挟大量沙尘粒子影响敦煌地区, AOD和α变化范围最大, 分别为0.11–1.18和0.06–0.82; 夏季西北短程气团携带大量城市气溶胶污染敦煌地区, 而秋季主要来自西方气团对混合气溶胶的输送影响; 冬季三种气团作用下, AOD和α变化范围相似, 表明冬季不同来向气团对局地污染物具有相同的扩散作用.