Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Accurate lidar ratio (LR) and better understanding of its variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on climate. Using the observational data of a Raman lidar in Shanghai...

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Bibliographic Details
Published in:Atmospheric chemistry and physics 2021-04, Vol.21 (7), p.5377-5391
Main Authors: Liu, Tongqiang, He, Qianshan, Chen, Yonghang, Liu, Jie, Liu, Qiong, Gao, Wei, Huang, Guan, Shi, Wenhao, Yu, Xiaohong
Format: Article
Language:English
Subjects:
Accuracy
Aerosol effects
Aerosols
Air masses
Atmospheric turbidity
Biomass burning
Burning
Depolarization
Distribution
Haze
Height
Irregular particles
Lasers
Lidar
Lidar measurements
Optical properties
Optical radar
Particle shape
Physical properties
Pollutants
Product reliability
Remote sensing
Shape
Turbidity
Variation
Vertical distribution
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Summary:Accurate lidar ratio (LR) and better understanding of its variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on climate. Using the observational data of a Raman lidar in Shanghai from 2017 to 2019, LRs at 355 nm were retrieved and their variations and influence factors were analyzed. Within the height range of 0.5–5 km, about 90 % of the LRs were distributed in 10–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase in height. The volume depolarization ratio (δ) was positively correlated with LR, and it also decreased with the increase in height, indicating that the vertical distribution of particle shape was one of the influence factors of the variations in LR with height. LR had a strong dependence on the original source of air masses. Affected by the aerosols transported from the northwest, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distribution of LR was affected by atmospheric turbidity, with the greater gradient of LR under clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by biomass burning aerosols.
ISSN:1680-7324
1680-7316
1680-7324
DOI:10.5194/acp-21-5377-2021