关于地形绕流作用的数值模拟

Numerical Experiments on the Detour Airflow Forced by Mountains

本文的目的是为了研究复杂地形中的中尺度环流特征。在统计分析黑龙江省地形－环流－暴雨关系的基础上，应用一层σ坐标中尺度模式对局部复杂地形进行数值模拟。选取的个例是一次北上台风和西风带冷空气相结合的暴雨过程。模拟结果表明，有一些明显的中尺度地形辐合带（１００～２００ｋｍ）与暴雨中心相对应。最强的辐合带出现在喇叭口地形附近。另外，在一些山包背风坡也有较强的辐合带。理想的椭圆形孤立山地的试验，更清楚看出地形周围的气流分布。绕流作用造成的迎风坡辐散和背风坡辐合非常明显。这说明，在暴雨中尺度诊断分析中，除了考虑地形爬坡作用外，还必须重视地形的绕流作用。

The effects of topography on the surface layer winds were diagnosed by using a one-level mesoscale model. Some convergence lines forced by complex ter-rain were found in the leeside of mountains and coinsided with the heavy rainfall。The results of these experiments indicate that the influence created by the deflectionof low-level flow around the mountains would be seriously considered in the mesoscale diagnostic analysis of the heavy rainfall,especially in the leeward side。