Based on the near-surface atmospheric turbulence observation in the National Observation and Research Station of Desert Meteorology, Taklimakan Desert of Xinjiang in July 2016, the characteristics of turbulent transport in the unstable atmospheric surface layer in the hinterland of Taklimakan Desert are investigated. With the methods of eddy covariance, quadrant analysis, and spectra analysis, the dissimilarity between the turbulent transport of heat and momentum under different atmospheric instability is analyzed, and its potential physical mechanism is further explored. The results indicate that, under near-neutral conditions, the turbulent transport of heat and momentum is similar. However, as the atmospheric instability increases, the transport dissimilarity between heat and momentum becomes increasingly significant. Heat is transported more efficiently than momentum, while the turbulent transport of momentum shows a great randomness under the strongly thermal condition. This dissimilarity is closely related to the topology of turbulent coherent structures. Under unstable conditions, the coherent structure is dominated by thermal plume. It can induce synchronous changes in potential temperature and vertical velocity, but is difficult to lead corresponding changes in horizontal velocity. The difference in the physical mechanism of turbulent motion is the main reason for the significant dissimilarity between the turbulent transport of heat and momentum with increasing atmospheric instability.

利用2016年7月新疆塔克拉玛干沙漠气象国家野外科学观测研究站近地面层大气湍流实验观测资料, 采用涡动相关、象限分析和频谱分析等方法, 研究塔克拉玛干沙漠腹地强热力作用下近地面层湍流特征, 对比分析热量输送与动量输送的差异, 探讨输送差异的成因和物理机制。研究结果表明, 近中性层结条件下, 塔克拉玛干沙漠腹地近地面层湍流运动对热量和动量的输送作用类似; 随着大气不稳定度增加, 热量与动量的输送差异增大。在强热力条件下, 湍流运动对热量的输送效率较高, 但对动量的输送存在较大的随机性。输送差异形成的原因与湍流相干结构密切相关, 在不稳定层结条件下, 湍流相干结构以热羽为主, 能够引起位温和垂直速度的同相位变化, 但较难引起水平速度的相应变化。湍流运动的动力和热力响应物理机制不同, 是热量与动量的输送差异及其随大气不稳定度增强而增大的主要原因。