有地形存在时对流云发展的数值模拟研究

NUMERICAL SIMULATION OF THE DEVELOPMENT FOR CONVECTIVE CLOUDS OVER TERRAIN

本文通过应用地形转换坐标，建立了一个能够模拟复杂地形上对流云发展的二维非静力的弹性模式，并对以下几个方面进行了模拟实验：首先对初始环境场的调整适应过程进行了模拟研究，得到：在有对流云发展的情况下，只要调整适应时间大于一个浮力振荡周期（即２π／Ｎ），则此时间尺度的大小只对对流云的发展强度产生影响，而对其发展的趋势影响不大。然后我们对下述过程进行了模拟：①地形抬升对积云的触发作用；②上坡环流对已发展对流云的加强；③下坡环流对已发展对流云的减弱。模拟结果表明，模式是稳定的、可靠的。上述模拟研究为我们今后深入开展强对流云数值模拟工作打下了基础。

This paper describes a two-dimensional elastic cloud model by using a terrainfollowing coordinate transformation, which can be used to simulate the development of convective cloud over irregular lower surface. The model is tested from two aspects.First, the initialization or start-up procedure is testd. The results indicate: as long as the initialization time scale is larger than 2 * PAI/N (PAI= 3. 14156, N the Brunt Vaisala Frequency), this time scale only affects the strength of the convective cloud, and doesn't affect the developing trend of the convective cloud.Second, the influence of upslope and downslope on the development of convective clound is simulated. It is found that: 1. An upslope can promote the development of cloud validly, and can produce convective cloud as long as the temperature and humity condition is adaptable; 2. A downslope can restrain the development of convective cloud.The results prove: the model is stable and reliable, and is our work base for simulating convective cloud in future.