Jingjing Ren1, Wangshu Tan2, Xiaoqing Tian1, Zhaolong Wu1, Chengcai Li1*, Jing Li1, Chunsheng Zhao1, Dong Liu3, Ling Kang4, Tong Zhu4, 5
1 Department of Atmosphere and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
2 School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
3 State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
4 State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Science & Engineering, Peking University, Beijing 100871, China
5 Beijing Innovation Center for Engineer Science and Advanced Technology, Peking University, Beijing 100871, China
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Aerosol liquid water content (ALWC) has significant effects on aerosol optical properties, radiative forcing, and the development of severe pollution events. In this study, the vertical distribution and temporal evolution of ALWC were determined through linear particle depolarization measured by a High Spectral Resolution Lidar (HSRL) from December 9 to 12, 2020. Near-surface ALWC datasets retrieved by HSRL were validated by measurements from a three-wavelength humidified nephelometer. The ALWC datasets derived by two methods were highly correlated (R = 0.94, N = 192), illustrating the feasibility of retrieving the ALWC by HSRL. A positive correlation between the ALWC and the enhancement of aerosol scattering coefficient F calculated by the scattering coefficient at 525 nm measured in dry and ambient states proves the reliability of the ALWC obtained from HSRL. However, previous research has implied that fine mode particles dominating the total aerosol loading are required to precisely retrieve the ALWC, while the uncertainty of ALWC data will be large when the particle depolarization ratio is larger than 0.07. When the particle depolarization ratio is less than 0.07, the ALWC derived from HSRL has high precision. By analyzing the aerosol property measurements (e.g., PM2.5, PM10, particle depolarization ratio, and scattering coefficient) near the surface, we found that ALWC contributes greatly to the deterioration of visibility. The variability of optical parameters in the vertical direction showed that ALWC significantly promotes the enhancement of aerosol extinction coefficient. Moreover, high ALWC will significantly increase the scattering capacity of aerosols, leading to an enhanced cooling effect on the climate system.
Citation: Ren, J., W. Tan, X. Tian, Z. Wu, C. Li, J. Li, C. Zhao, D. Liu, L. Kang & T. Zhu, 2021. Retrieval of aerosol liquid water content from high spectral resolution lidar. Science of The Total Environment, 149423, https://doi.org/10.1016/j.scitotenv.2021.149423.