山地边界层中场变量的动力学研究

DYNAMIC STUDY OF FIELD VARIABLES IN THE PLANETARY BOUNDARY LAYER ABOVE OROGRAPHY

中文关键词:  行星边界层  场变量  动力学研究

英文关键词:PBL  Field variable  Dynamic study

中文摘要:

      采用与实测较接近的二次函数来表达Ekman层中的湍流粘性系数K,在圆形气压场条件下,求得了山地上空边界层中的风速,进而求得散度、涡度和垂直速度等场变量随高度的分布。并作图分析了这些场变量的一些动力学特征。改进了以往在求解析解时,略去运动方程中湍流粘性力项中的关于高度的一阶导数项,以及取山坡面上风速为零作下边界条件等欠合理欠精确的做法。所求得的风速、散度、涡度和垂直速度均用简单的初等函数表示出来,有助于边界层参数化和深化对边界层动力学的认识。

英文摘要:

      By use of the eddy exchange coefficient K expressed by the quadratic function in Ekman layer which is close to observation. and under the condition of circle pressure field. the wind velocity in the planetary boundary layer(PBL) is obtained. Further, the distributions with height of field varibles of divergence. vorticity and vertical velocity are gained. In this paper, the first order derivation in the term of eddy discocity force in the motion equation and the lower boundary condition that the wind velocity at the mountain slope is not zero are counted. In the past. both of these are often neglected. The wind velocity, divergence. vorticity and vertical velocity are expressed by the simple elementary functions in this paper which is helpful for the parameterization and the deepening of dynamics cognation for the PBL.