State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Institute for Advanced Sustainability Studies, Potsdam, Germany.
Environ Pollut. 2020 Oct;265(Pt B):114872. doi: 10.1016/j.envpol.2020.114872. Epub 2020 May 25.
This paper presents the results of the study on columnar aerosol optical and physical properties and radiative effects directly observed over Dushanbe, the capital city of Tajikistan, a NASA AERONET site (equipped with a CIMEL sunphotometer) in Central Asia. The average aerosol optical depth (AOD) and Ångström exponent (AE) during the observation period from July 2010 to April 2018 were found to be 0.28 ± 0.20 and 0.82 ± 0.40, respectively. The highest seasonal AOD (0.32 ± 0.24), accompanied by the lowest average AE (0.61 ± 0.25) and fine-mode fraction in AOD (0.39), was observed during summer due to the influence of coarse particles like dust from arid regions. Fine particles were found in significant amounts during winter. The 'mixed aerosol' was identified as the dominant aerosol type with presence of 'dust aerosol' during summer and autumn seasons. Aerosol properties like volume size distribution, single scattering albedo, asymmetry parameter and refractive index suggested the influence of coarse particles (during summer and autumn). Most of the air masses reaching this site transported local and regional emissions, including from beyond Central Asia, explaining the presence of various aerosol types in Dushanbe's atmosphere. The seasonal aerosol radiative forcing efficiency (ARFE) in the atmosphere was found high (>100 Wm) and consistent throughout the year. Consequently, this resulted in similar seasonally coherent high atmospheric solar heating rate (HR) of 1.5 K day during summer-autumn-winter, and ca. 0.9 K day during spring season. High ARFE and HR values indicate that atmospheric aerosols could exert significant implications to regional air quality, climate and cryosphere over the central Asian region and downwind Tianshan and Himalaya-Tibetan Plateau mountain regions with sensitive ecosystems.
本文呈现了在中亚的 NASA AERONET 站点（配备 CIMEL 太阳光度计）直接观测到的塔吉克斯坦首都杜尚别柱状气溶胶光学和物理特性及辐射效应的研究结果。在 2010 年 7 月至 2018 年 4 月的观测期间，气溶胶光学深度（AOD）和 Ångström 指数（AE）的平均值分别为 0.28 ± 0.20 和 0.82 ± 0.40。由于干旱地区的粗颗粒（如灰尘）的影响，夏季观察到最高的季节性 AOD（0.32 ± 0.24），同时平均 AE（0.61 ± 0.25）和 AOD 中的细模态分数（0.39）最低。冬季发现细颗粒含量较高。在夏季和秋季，“混合气溶胶”被确定为主要气溶胶类型，存在“沙尘气溶胶”。气溶胶特性，如体积大小分布、单次散射反照率、不对称参数和折射率表明，粗颗粒（夏季和秋季）存在影响。到达该站点的大部分空气团携带本地和区域排放物，包括来自中亚以外的排放物，这解释了杜尚别大气中存在各种气溶胶类型的原因。大气中季节性气溶胶辐射强迫效率（ARFE）很高（>100 Wm），并且全年一致。因此，这导致夏季-秋季-冬季大气太阳加热率（HR）相似，约为 1.5 K 天，而春季约为 0.9 K 天。高 ARFE 和 HR 值表明，大气气溶胶可能对中亚地区以及下风天山和喜马拉雅-青藏高原山区的区域空气质量、气候和冰冻圈产生重大影响，这些地区的生态系统较为敏感。
