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一、引 言 锋的地形效应的重要性,早已被天气学界所承认,但是至今尚未对这些效应作出动力学的研究。Bannon(1983)对于一些在表面地形上移动的处在伸展变形场中的准地转锋,求得了分析解。1984年,他得到了更普遍的半地转解,但这个解需要时变地形和低边界层条件部分初值化。Bannon(1983,1984)的研究结果表明,当一条锋在山坡上爬坡运动时,这个锋将减弱,而当它向下坡运动时,则加强。在文中我们将发展一个数值模式,这个模式将会消除Bannon(1984)所用到的近似值。这一模式是Williams(1972)对一个锋生研究的扩展模式的变形。将一个随地形起伏的垂直坐标引入到简化的地形内含中去。还要使用周期性边界条件,变形场的风分量变为正弦的形式,这些边界条件从数值方法的角度来说是比较好的处理办法,而变形场则给出了一个运动着的天气扰动更合情合理的描述。
I. INTRODUCTION The importance of the topographic effect of the front has long been recognized by the weather academia, but so far no kinetic studies have been made on these effects. Bannon (1983) obtained analytic solutions for some quasi-geostrophic frontal translational extensional fields moving on surface topography. In 1984, he obtained a more general semi-transmutation, but this solution required a partial initialization of time-varying terrain and low-boundary layer conditions. The results of Bannon (1983, 1984) show that when a striker moves uphill, the front weakens, and when it moves downhill, it strengthens. In the text we will develop a numerical model that will eliminate the approximation used by Bannon (1984). This model is a variation of the expansion of Williams’ (Williams) research on a fronto-striker. Introduce a vertical coordinate with undulating terrain into a simplified terrain inclusion. But also the use of periodic boundary conditions, the wind component of the deformation field becomes sinusoidal, these boundary conditions are a better approach from a numerical method point of view, and the deformation field gives a moving weather disturbance more Reasonable description.