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Multi-Year Analyses of Columnar Aerosol Optical and Microphysical Properties in Xi’an, a Megacity in Northwestern China

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Key Lab of Aerosol Chemistry & Physics, Chinese Academy of Sciences (KLACP), Chinese Academy of Sciences, Xi’an 710061, China
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State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
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Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China
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Key Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Author to whom correspondence should be addressed.
Remote Sens. 2018, 10(8), 1169; https://doi.org/10.3390/rs10081169
Received: 21 June 2018 / Revised: 17 July 2018 / Accepted: 19 July 2018 / Published: 24 July 2018
(This article belongs to the Section Atmosphere Remote Sensing)
A thorough understanding of aerosol optical properties and their spatio-temporal variability are required to accurately evaluate aerosol effects in the climate system. In this study, a multi-year study of aerosol optical and microphysical properties was firstly performed in Xi’an based on three years of sun photometer remote sensing measurements from 2012 to 2015. The multi-year average of aerosol optical depth (AOD) at 440 nm was about 0.88 ± 0.24 (mean ± SD), while the averaged Ångström Exponent (AE) between 440 and 870 nm was 1.02 ± 0.15. The mean value of single scattering albedo (SSA) was around 0.89 ± 0.03. Aerosol optical depth and AE showed different seasonal variation patterns. Aerosol optical depth was slightly higher in winter (0.99 ± 0.36) than in other seasons (~0.85 ± 0.20), while AE showed its minimum in spring (0.85 ± 0.05) due to the impact of dust episodes. The seasonal variations of volume particle size distribution, spectral refractive index, SSA, and asymmetry factor were also analyzed to characterize aerosols over this region. Based on the aerosol products derived from sun photometer measurements, the classification of aerosol types was also conducted using two different methods in this region. Results show that the dominant aerosol types are absorbers in all seasons, especially in winter, demonstrating the strong absorptivity of aerosols in Xi’an. View Full-Text
Keywords: optical and microphysical properties; sun photometer; semi-arid megacity optical and microphysical properties; sun photometer; semi-arid megacity
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MDPI and ACS Style

Su, X.; Cao, J.; Li, Z.; Li, K.; Xu, H.; Liu, S.; Fan, X. Multi-Year Analyses of Columnar Aerosol Optical and Microphysical Properties in Xi’an, a Megacity in Northwestern China. Remote Sens. 2018, 10, 1169.

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