A numerical study of second-order turbulent moments in the stably stratified nocturnal boundary layer

The structures and the vertical profiles of turbulent variance and covariance of the stably stratified boundary layer (SBL) are simulated with a second-order closure turbulence model. The results confirm that the vertical profiles of the dimensionless turbulence variance and covariance can be well represented by the formF = A(1-Z / h)α. Hereh is the height of SBL, and both exponent α and coefficientA are the functions of terrain, baroclinicity, radiation cooling and the state of temporal development of SBL. Comparing with Minnesota and Cabauw experiment data, we have analysed the value of χ and expounded the main reasons that great difference in α exists among different literatures.