关键词: 塔克拉玛干沙漠, 晴空, 对流边界层, 大涡模拟, 热对流泡, 湍流动能

Abstract: Large-eddy simulation of clear sky convective boundary layer is carried out with sounding and surface flux observation data in the hinterland of Taklimakan Desert so as to explore the structure of the turbulence and the law of heat convection of summer clear sky boundary layer in the Desert. The study shows that:(1) Under the summer clear sky in the Taklimakan Desert, the boundary layer turbulent kinetic energy is mainly generated by the surface thermal buoyancy convection. The dissipation of turbulent kinetic energy triggered by small-scale eddy weakens as the increase of the height. The variation of the boundary layer turbulent kinetic energy has the feature of intermission.(2) Organized thermal bubbles appear in the boundary layer. The maximum ascending speed of the thermal bubbles exceeds 4.0 m·s^-1; the thermal convection in Taklimakan Desert generally shows the pinnate and network-like distribution, with a large area of sinking divergence around the upward motion area.(3) The surface sensible heat and the intensity at the top of the inversion layer are two important factors controlling and influencing the development of the convective boundary layer in Taklimakan Desert. If the sensible heat increases, the boundary layer becomes warmer and its height also increases; if the sensible heat decreases, the boundary layer becomes colder and its height also decreases. When the sensible heat remains the same, the stronger the intensity at the top of the inversion layer is, the more negative influence it will have on the development of the convective boundary layer, vice versa.

Key words: Taklimakan Desert, clear sky, convective boundary layer, large-eddy simulation, thermal bubble, turbulent kinetic energy