Articles | Volume 9, issue 3
Research article
01 Apr 2016
Research article |  | 01 Apr 2016

Observations of water vapor mixing ratio profile and flux in the Tibetan Plateau based on the lidar technique

Songhua Wu, Guangyao Dai, Xiaoquan Song, Bingyi Liu, and Liping Liu

Abstract. As a part of the third Tibetan Plateau Experiment of Atmospheric Sciences (TIPEX III) in China, a Raman water vapor, cloud and aerosol lidar and a coherent wind lidar were operated in Naqu (31.48° N, 92.06° E) with a mean elevation of more than 4500 m a.m.s.l. in summer of 2014. During the field campaign, the water vapor mixing ratio profiles were obtained and validated by radiosonde observations. The mean water vapor mixing ratio in Naqu in July and August was about 9.4 g kg−1 and the values vary from 6.0 to 11.7 g kg−1 near the ground according to the lidar measurements, from which a diurnal variation of water vapor mixing ratio in the planetary boundary layer was also illustrated in this high-elevation area. Furthermore, using concurrent measurements of vertical wind speed profiles from the coherent wind lidar, we calculated the vertical flux of water vapor that indicates the water vapor transport through updraft and downdraft. The fluxes were for a case at night with large-scale non-turbulent upward transport of moisture. It is the first application, to our knowledge, to operate continuously atmospheric observations by utilizing multi-disciplinary lidars at the altitude higher than 4000 m, which is significant for research on the hydrologic cycle in the atmospheric boundary layer and lower troposphere in the Tibetan Plateau.

Short summary
The water vapor expedition experiment was operated in the Tibetan Plateau during July and August 2014, by using water vapor, cloud, and aerosol lidar. During the observations, water vapor mixing ratio at high elevation was obtained. The validation of water vapor mixing ratio was completed by comparing the lidar measurements to radiosonde data. Finally, with the vertical wind speed, the vertical flux of water vapor is calculated and the upwelling and deposition of the water vapor are monitored.