地形对大气环流影响的数值试验

本文利用北半球正压原始方程模式和理想初始场，加入北半球实际的平滑地形的作用，对北半球超长波2波型、3波型、长波4波型、5波型，分别进行了240小时的积分计算。从考虑地形和不考虑地形的四组结果对比中，发现地形对上述四种波型的演变有很大的影响，证实了地形作用确系影响大气环流、形成某些天气气候特征的重要因素之一；同时发现，在地形的动力作用下，北半球大气形成了一些重要的环流系统。例如，极涡向北欧偏移，东亚、北美大槽和阿拉斯加脊的维持，都与地形有密切关系。在地形作用下:（1）北太平洋西槽东脊，而北大西洋西脊东槽。（2）阻塞和切断形势的出现更为频繁、典型。（3）在欧亚大陆上，m=4时出现倒Ω流型，而m=5时，出现两槽一脊型。

A Numerical Simulation of the Effect of Relief on Atmospheric Circulation

In this paper, a barotropic primitive equations model in the Northern Hemisphere and ideal initial field are used. The altitude of the smooth relief is considered in the model. The equations are integrated through 240 hours for some wave systems in which the wave numbers are 2, 3 (ultra–long wave), 4 and 5 (long wave), respectively. Comparing these solutions with those obtained from the model in which the altitude of the relief is not considered. Four pairs of the solutions show that the effect of the altitude on the evolution of the four sorts of wave types is very obvious. It is confirmed that the effect of the relief on the general circulation and some characteristics of weather types is really one of the key factors. It is also found that some main patterns of atmospheric circulation in the Northern Hemisphere are formed due to the dynamical effect of the relief. For example, the movement of the arctic vortex to North Europe, the maintained troughs over East Asia and North America, and the maintained ridge over Alaska are closely related to the relief. In this model, the effects of the relief present: A trough is in the west and a ridge is in the east of the North Pacific, while a ridge is in the west and a trough is in the east of North Atlantic. The presences of blocking highs and cut–off lows are more frequent and more typical. As m=4, the flow pattern looks like a upside–down Ω, while m=5, the flow pattern is trough–ridge–trough over the continent of Europe and Asia