复杂地形上稳定边界层二维流场的数值模拟

建立了一个二维局地尺度数值模式，对水平扩散采用了水平平滑处理方法，提出了一种在地形追随坐标系中具有较高计算精度的差分近似方法，此方法兼具了地形追随坐标系和直角坐标系的优点，特别适用于地形特征尺度较小和垂直分层要求较细的情况。数值试验表明：该模式具有模拟局地尺度环流的能力，且计算机内存和ＣＰＵ时间都较节省，算法稳定。利用所建立的模式对经过重庆市中区的某一实际地形下的流场进行了数值模拟。

A TWO-DIMENSIONAL NUMERICAL MODEL ADOPTED TO SIMULATE LOCAL-SCALE CIRCULATIONS OVER INHOMOGENOUS TERRAIN UNDER STABLE CONDITIONS

A two-dimensional numerical model was developed to simulate local-scale circulations over inhomogenous terrain under stable conditions. A horizontal smoother was used in lieu of explicit horizontal diffusions. An improved finite difference scheme for approximating horizontal derivates in a terrain-following coordinate system was introduced. With this methodology, the error in calculation of the horizontal advection could be greatly reduced,especially in situations where the terrain is steep and the vertical grid space is small.By using this model, some experiments have been carried out under ideal conditions.The results show that the model has the capacity of simulating local-scale circulations.The model is also used to simulate the local-scale circulations induced by mountain, city island and water surface in Chongqing. The results are in good agrement with observations.