Abstract
One-year observation of dust aerosol properties near Hexi Corridor was obtained from polarimetric measurements by ground-based sunphotometer in the county of Minqin in northwestern China from March 2012 to February 2013. We observed an annual mean AOD of0.22±0.22at 0.50 μm and Ångström exponents of 0.1–1.0 fitting a bimode normal distribution centered at 0.18 and 0.50, respectively. The effective radii of fine (0.13–0.17 μm) and coarse (2.49–3.49 μm) modes were found stable at all seasons together with the appearance of a third mode of particle radius at 0.4–1.0 μm when AOD was larger than 0.6. It is noticeable that the real (1.5–1.7) and imaginary (0.0005 to 0.09) parts of complex refractive indices were higher than other studies performed in other desert regions of China, while single scattering albedo was relatively lower (~0.84–0.89) at wavelengths of 0.44, 0.67, 0.87, and 1.02 μm. This is partially due to calcite or hematite in the soil in Minqin or the influence of anthropogenic aerosols containing carbon. Moreover, from our novel polarimetric measurement, the scattering phase function (F11) and degree of linear polarization for incident unpolarized light (-F12/F11) of dust aerosols were also obtained within this deserted area.
Highlights
Dust aerosols are common natural particles suspending in terrestrial atmosphere
Knowledge of optical properties of Chinese dust aerosols is not enough and the radiative impact is poorly known as well. This is in part due to the complexity of the properties of mineral dust aerosols which depend on size, shape, and orientation [3] and in part due to the lack of longterm rigorous observation in this region
Che et al [14] exhibited the frequency distribution of AODs over Taklimakan Desert in China. Their histogram was fitted by two peaks; that were the mode centered at ∼0.23 probably corresponding to nondust atmospheric and the mode centered at ∼0.50 caused by higher mineral dust burden in atmosphere
Summary
Dust aerosols are common natural particles suspending in terrestrial atmosphere. According to mineralogy, there are thousands of mineral species in global crust such as illite, kaolinite, gypsum, smectite, quartz, calcite, and hematite, each of which has a specific chemical composition, molecular structure, and physical morphology [1]. Knowledge of optical properties of Chinese dust aerosols is not enough and the radiative impact is poorly known as well. This is in part due to the complexity of the properties of mineral dust aerosols which depend on size, shape, and orientation [3] and in part due to the lack of longterm rigorous observation in this region. Databases containing experimental scattering matrices of mineral dust particles were developed [6, 7] Apart from these highquality laboratory measurements, the optical and physical properties of dust aerosols can be retrieved by ground-based sunphotometer [8,9,10]. 2013 and the results and analysis are shown
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