摘要
将σ-坐标的运动方程组进行尺度分析,考虑水平尺度为10^(3)公里的系统,得到一组封闭的简化方程组。在涡度方程中,凸起的地形脊对流场的影响和一固定的气旋式流场相当;在热力学方程中和一固定的高温区相当。因此,引入了地形相当涡度和地形相当温度的概念来近似表示这种影响。当把运动分解为平流变化和调整变化的相互作用来考察,并且平均气流和切变气流均为西风时,调整变化所造成的垂直运动和边界条件的强迫作用相反,有利于保持大尺度运动的准水平性。但在某些特殊条件下,调整变化可和边界的强迫作用相一致,可进一步加强边界条件的影响。
A simplified equation system inσ-coordinate system is obtained by scale analysis for horizontal scale,L~10^(3)km.The mountain effect on the wind field in vorticity equation is equivalent to a fixed cyclonic center,but on temperature field in thermodynamic equation,it is equivalent to a fixed high temperature center.In order to describe these effects,the concepts of the topographic equivalent vorticity and the topographic equivalent temprature are introduced.The large scale atmospheric motion under the influence of topographic is also divided into two parts:the advecting change and adjusting change.Each of these parts and their interaction are discussed.Under the condition of the mean and vertical shear westerly current over a mountain,the ageostrophic wind or non-thermal wind may be produced by the advecting process then the vertical motion is caused by the internal adjusting process.But in this case this vertical motion is opposed to that forced directly by boundary condition,however,under some special cases the vertical motion caused by the internal adjusting process and directly by boundary condition may have same direction.These properties is very important to estimate the vertical motion in the weather forcasting。
作者
陈秋士
Ghen Qiu-Shi(Ghen Ghiu-Shih)(Department of Geophysics,Peking University)
出处
《气象学报》
1979年第4期88-102,共15页
Acta Meteorologica Sinica
