Observational evidence of the combined influence of atmospheric circulations and local factors on near-surface meteorology in Dagze Co basin, inner Tibetan Plateau

Based on meteorological observations of three automatic weather stations (AWSs), spanning an altitudinal range of 1400 m from 4480 to 5880 m above sea level (m a.s.l.) during August 2015 to August 2016, this study presents a description of the spatio-temporal characteristics of the near-surface meteorology of the Dagze Co (lake) basin in the interior of the Tibetan Plateau. We also investigated the influence of synoptic atmospheric systems and local factors on the meteorological characteristics. We found that the onset and withdrawal of the South Asian summer monsoon triggered seasonal shift in meteorological variables including wind direction, precipitation, and relative humidity. In addition, the magnitude of various meteorological factors during the monsoonal period is clearly associated with the intensity of the South Asian summer monsoon, which subsequently controls the lake water budget of Dagze Co. Moreover, both the local topography and the existence of the lake contribute significantly to the altitudinal variation of several meteorological factors. For example, the orographic precipitation near the glaciated area at 5880 m a.s.l. was about three times greater than in the area adjacent to the lake. The dominating katabatic wind over these glaciated areas weakens the up-valley wind and consequently wind speed tends to decrease with increasing elevation during the monsoonal season. In addition, different levels of cloudiness between the low-altitude lake and the glaciated mountain area contribute to a 40-50% reduction in incoming short-wave radiation receipt. Our observations will hopefully contribute to future glacio-hydrological studies and will help to evaluate statistically/dynamically downscaled climate fields in the interior of Tibetan Plateau which contains numerous lakes and glaciers.