摘要
在大气边界层中,当温度分布在水平方向不均匀时,斜压性必须予以考虑。本文在地转动量近似条件下,采用Agee[1]公式来描述湍流粘性系数K,求得斜压边界层中风场分布的解析表达式。由求得的解析解和个例的图解均分析得出一些与经典Ekman理论很不相同的动力学特征。例如,在边界层上部,冷平流使气旋中的风速随高度增大而一直增大,且一直指向低压一方,不再呈Ekman螺线状。在边界层下部,例如20米处,引进热成风将使风向改变达25°左右。这对预报边界层风场是很重要的修正。
In the atmospheric boundary layer, the baroclinity must be considered when the temparature distribution is inhomogeneous in horizontal direction. In this paper, the analvtic expressions of the wind velocities within the baroclinic boundarv layer are obtained incoroprating the geostrophic momentum approximation by use of Agee formula to describe the turbulent viscositv coeficient K. From the analvtic solutions and the diagram of an example we can see that the present model has some different dynamic characteristics in comparison with the classical Ekman boundary laver model. For example, in the upper part of the Ekman boundary layer, the cold advectioa effect enables the wind in the cyclone vortex to increase monotonously with height and to direct to the lower pressure side. The hodograph of wind is no longer the classical Ekman spiral. In the lower part of the Ekman boundary layer, for instance, at 20 meter level, the direction of the wind can change about 25 after introducing the thermal wind. This is an important improvement for the prediction of wind field in the Ekman boucdary layer.
出处
《气象科学》
CSCD
北大核心
1989年第1期1-15,共15页
Journal of the Meteorological Sciences
