区域模式双向嵌套技术的理想试验分析

Analysis Idealized Test of Two-Way Grid Nesting in Mesoscale Model

利用线性浅水波方程进行嵌套试验,对比分析了单、双向嵌套在不同边界条件下对虚假计算反射波的抑制作用,以及多重嵌套后各嵌套区域之间相互影响等问题。结果发现,双向嵌套在抑制虚假计算反射波方面要优越于单向嵌套,虽然对于短波双向嵌套表现较差,但可使用滤波海绵边界条件加以克服。由于采用双向嵌套,嵌套的子区域内产生的虚假计算反射波会同时被反馈到其母区域中而扭曲了粗网格的波动,因此在使用双向嵌套时需要很好的控制虚假计算反射波。最后通过个例模拟,对比了单向嵌套与双向嵌套的模拟结果,验证了双向嵌套的优点。

Although nested grids are extensively used in numerical modeling of the atmosphere for a wide range of applications,theoretical analyses of grid nesting were hardly seen and researches on grid nesting were mostly centered on the comparison of results of real case simulation using different nesting methods. This paper presents results from a grid nesting experiment using the linear shallow water equations to compare the ability of controlling the fake wave reflections of one-way nesting and two-way nesting under different boundary conditions,and also analyses the interactive impact of multi-nesting areas. Two-way nesting was found to be generally superior to one-way nesting in the capacity of controlling the fake wave reflections,although it's bad performance on shorter wave can be overcome using the filtered sponged boundary conditions. Because of the fake wave disturbances of children nesting areas can be feedback to the parent domain when using two-way nesting,we must have a good control of the fake wave disturbances. Also,this paper presents a comparison of one-way and two-way nesting using WRF mesoscale model which shows the superiority of two-way nesting.