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一、引言 原始方程模式现在已应用于飓风预报业务。要模拟飓风内核的结构,将需要一个格距为5公里或更小的网格,可是在业务模式中使用40公里或更大的网格以节省计算时间。因为在风暴地区获得的资料极少,所以在大尺度的分析场上加一个理想化的涡旋可以获得小尺度的初始涡旋。实际情况是,初始化的涡旋的尺度、结构和强度常常与观测到的风暴很不相同。这些模式的主要目的是预报飓风的路径,预报的风暴强度和结构没有用观测进行常规的检验。 目前的数值积分显示出,一个像飓风一样的涡旋,能够用一个以40km格距的网格来模拟。初始的对称的弱涡旋加强到一个飓风。模拟得真实的飓风特征包括:在中心周围垂直运动场中的有规则的带,眼区的向下运动;在对流层上部的气旋性流出气流以及中心的暖心。当一个均匀的引导气流迭加到初始涡旋上时,涡旋的运动将偏向引导气流的北方并迅速加强。几个实验结果指出,运动及其增强速率取决于初始涡旋的尺度、强度和垂直结构以及环境流场。
I. Introduction The original equation model has now been applied to hurricane forecasting business. To mimic the structure of a hurricane core, you will need a grid with a grid spacing of 5 kilometers or less, but using grids of 40 kilometers or more in business models to save computing time. Because there is very little data available in storm areas, an idealized vortex on a large-scale analysis field can obtain small-scale initial vortices. The reality is that the scale, structure and intensity of the initial vortex are often very different from the observed storm. The main purpose of these models is to predict the path of the hurricane. The storm intensity and structure of the forecast are not routinely tested with observations. The current numerical integration shows that a hurricane-like vortex can be modeled by a grid of 40 km grids. The initial symmetrical weak vortex strengthens to a hurricane. The simulated true hurricane features include a regular band in the vertical motion field around the center, a downward movement of the eye area, a cyclonic effluent stream in the upper troposphere and a center of warmth. When a uniform pilot flow is superimposed on the initial vortex, the vortex motion will tend to direct north of the flow and intensify rapidly. Several experimental results indicate that the motion and its rate of enhancement depend on the scale, intensity and vertical structure of the initial vortex and the ambient flow field.