Abstract

A combination of more than two years of water vapor lidar data with back trajectory analysis using the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was used to study the long-range transport of air masses and the water vapor distribution characteristics and variations over Xi’an, China (34.233° N, 108.911° E), which is a typical city in Northwest China. High-quality profiles of the water vapor density were derived from a multifunction Raman lidar system built in Xi’an, and more than 2000 sets of profiles with $>400$ nighttime observations from October 2013 to July 2016 were collected and used for statistical and quantitative analyses. The vertical variations in the water vapor content were discussed. A mutation height of the water vapor exists at 2–4 km with a high occurrence rate of $\sim 60\%$ during the autumn and winter seasons. This height reflects a distinct stratification in the water vapor content. Additionally, the atmospheric water vapor content was mainly concentrated in the lower troposphere, and the proportion of the water vapor content at 0.5–5 km accounted for 80%–90% of the total water vapor below 10 km. Obvious seasonal variations were observed, including large water vapor content during the spring and summer and small content during the autumn and winter. Combined with back trajectory analysis, the results showed that markedly different water vapor transport pathways contribute to seasonal variations in the water vapor content. South and southeast airflows dominated during the summer, with 30% of the 84 trajectories originating from these areas; however, the air masses during the winter originated from the north and local regions (64.3%) and from the northwest (27%). In addition, we discussed variations in the water vapor during fog and haze weather conditions during the winter. A considerable enhancement in the mean water vapor density at 0.5–3 km exhibited a clear positive correlation (correlation coefficient $>0.8$) with the PM2.5 and PM10 concentrations. The results indicate that local airflow trajectories mainly affect water vapor transport below the boundary layer, and that these flows are closely related to the formation of fog and haze events in the Xi’an area.

© 2017 Optical Society of America

Observation and analysis of the temperature inversion layer by Raman lidar up to the lower stratosphere

Yufeng Wang, Xiaoming Cao, Tingyao He, Fei Gao, Dengxin Hua, and Meina Zhao
Appl. Opt. 54(34) 10079-10088 (2015)

Six-channel multi-wavelength polarization Raman lidar for aerosol and water vapor profiling

Zhaofei Wang, Jiandong Mao, Juan Li, Hu Zhao, Chunyan Zhou, and Hongjiang Sheng
Appl. Opt. 56(20) 5620-5629 (2017)

Preliminary exploration of atmospheric water vapor, liquid water and ice water by ultraviolet Raman lidar

Wang Yufeng, Wang Qing, and Hua Dengxin
Opt. Express 27(25) 36311-36328 (2019)

Automated detection of cloud and aerosol features with SACOL micro-pulse lidar in northwest China

Hailing Xie, Tian Zhou, Qiang Fu, Jianping Huang, Zhongwei Huang, Jianrong Bi, Jinsen Shi, Beidou Zhang, and Jinming Ge
Opt. Express 25(24) 30732-30753 (2017)

Aerosol optical properties and direct radiative forcing at Taihu

Rui Lü, Xingna Yu, Hailing Jia, and Sihan Xiao
Appl. Opt. 56(25) 7002-7012 (2017)