Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China

Wang, Xin; Wen, Hui; Shi, Jinsen; Bi, Jianrong; Huang, Zhongwei; Zhang, Beidou; Zhou, Tian; Fu, Kaiqi; Chen, Quanliang; Xin, Jinyuan

Mineral dust aerosols (MDs) not only influence the climate by scattering and absorbing solar radiation but also modify cloud properties and change the ecosystem. From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of MDs near dust source regions in Wuwei, Zhangye, and Dunhuang (in chronological order) along the Hexi Corridor over northwestern China. Throughout this dust campaign, the hourly averaged (inline-formula±standard deviation) aerosol scattering coefficients (inline-formulaσsp, 550 nm) of the particulates with aerodynamic diameters less than 2.5 inline-formulaµm (PMinline-formula2.5) at these three sites were sequentially 101.5 inline-formula± 36.8, 182.2 inline-formula± 433.1, and 54.0 inline-formula± 32.0 Mminline-formula−1. Correspondingly, the absorption coefficients (inline-formulaσap, 637 nm) were 9.7 inline-formula± 6.1, 6.0 inline-formula± 4.6, and 2.3 inline-formula± 0.9 Mminline-formula−1; single-scattering albedos (inline-formulaω, 637 nm) were 0.902 inline-formula± 0.025, 0.931 inline-formula± 0.037, and 0.949 inline-formula± 0.020; and scattering Ångström exponents (inline-formulaÅsp, 450–700 nm) of PMinline-formula2.5 were 1.28 inline-formula± 0.27, 0.77 inline-formula± 0.51, and 0.52 inline-formula± 0.31. During a severe dust storm in Zhangye (i.e., from 23 to 25 April), the highest values of inline-formula M23inlinescrollmathml italic σ normal sp normal 2.5 20pt17ptsvg-formulamathimgb68e0eb2a45cb56c790c977360463c3a acp-18-2119-2018-ie00001.svg20pt17ptacp-18-2119-2018-ie00001.png (inline-formula∼ 5074 Mminline-formula−1), backscattering coefficient (inline-formula M26inlinescrollmathml italic σ normal bsp normal 2.5 21pt18ptsvg-formulamathimgbee4be5f494240970ba0041edfaabd91 acp-18-2119-2018-ie00002.svg21pt18ptacp-18-2119-2018-ie00002.png , inline-formula∼ 522 Mminline-formula−1), and inline-formulaω637 (inline-formula∼ 0.993) and the lowest values of backscattering fraction (inline-formulab2.5, inline-formula∼ 0.101) at 550 nm and inline-formula M33inlinescrollmathml normal Å normal sp normal 2.5 21pt19ptsvg-formulamathimg89716ac6694d969eb742d899e0877c7b acp-18-2119-2018-ie00003.svg21pt19ptacp-18-2119-2018-ie00003.png (inline-formula∼inline-formula−0.046) at 450–700 nm, with peak values of aerosol number size distribution (appearing at the particle diameter range of 1–3 inline-formulaµm), exhibited that the atmospheric aerosols were dominated by coarse-mode dust aerosols. It is hypothesized that the relatively higher values of mass scattering efficiency during floating dust episodes in Wuwei and Zhangye are attributed to the anthropogenic soil dust produced by agricultural cultivations.

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Wang, Xin / Wen, Hui / Shi, Jinsen / et al: Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China. 2018. Copernicus Publications.

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