塔克拉玛干沙漠腹地夜间稳定边界层观测个例分析

A Case Analysis of Nighttime Stable Boundary Layer Observation in the Hinterland of Taklimakan Desert

利用塔克拉玛干沙漠腹地2016年7月13-14日和26-27日GPS探空和地面气象观测资料,分析了塔克拉玛干沙漠夏季晴天夜间各气象要素垂直廓线特征。结果表明:夜间(21:00至次日08:00,北京时,下同)稳定边界层的厚度达到240 m。残余混合层最大厚度与前一天对流混合层厚度相当,随时间推移其厚度到10:15损耗近三分之一,残余逆温层顶盖厚度达到400 m;在残余逆温层顶盖和稳定边界层顶附近有风速极大值出现,而07:15稳定边界层顶附近有低空急流发展,其最大风速达到10.8 m·s^(-1);夜间低空处比湿的变化趋势是先增后减小再增大的过程,其最小值为2.95 g·kg^(-1),出现在04:15的稳定边界层顶附近。残余混合层内比湿随高度略微增大;夜间逆温层对水汽通量有阻挡和聚合的作用,使其在稳定边界层顶和残余混合层顶附近出现极大值,并于07:15达到最大值。垂直水汽通量于04:15在残余混合层中下部做下沉运动、上部和残余逆温层顶盖中做上升运动;同时,夜间陆面过程中,存在较强的辐射冷却和较小的摩擦速度,这也是形成较为浅薄的夜间稳定边界层主要的热力因素和湍流动力因素。

Based on the data of GPS sounding and ground weather observation data of 13 -14 and 26- 27 July 2016 in the hinterland of Taklimakan desert, the vertical profile characteristics of meteorological elements was an- alyzed in summer clear-sky Nighttime in this paper. It is revealed that the thickness of stable boundary layer is found to be 240 m at night E from 21：00 （Beijing time, the same as after） to the next day 08：001. The maximum thickness of the residual mixing layer is the same as that of the convective mixing layer the previous day. Over time, the maximum thickness is lost about one third at 10：15, and the thickness of the residual temperature inver- sion layer top cover is up to 400 m; There is a maximum of wind speed in the residual temperature inversion lay- er top cover, near stable boundary layer roof, there develop a low-altitude jet stream whose maximum wind speed has reached 10. 8 m · s-1 at 07：15; The change trend of specific humidity at the low altitude night is a process of increasing first, then decreasing and last increasing, and the minimum value is 2. 95 g · kg-j, which has appeared near stable boundary layer roof at 04：15. Specific humidity of the residual mixed layer enlarges slightly with height; the night temperature inversion layer has the effect of blocking and polymerization on water vapor flux, and makes it appear the relative maximum value in nighttime near the top of stable boundary layer and residual mixing layer, which reaches the peak value at 07：15. The vertical water vapor flux does the sinking movement in the middle to lower part of residual mixing layer, whereas does the ascending motion in the upper part of residual mixing layer and residual temperature inversion layer top cover at 04：15 ; At the same time, there are quite strong radiation cooling and relatively small frictional velocity in the nocturnal land surface process, which are also the main thermodynamic factors and turbulent dynamic factors that form the relatively shallow nighttime stable boundary layer.