非平直基流中尺度扰动的对称发展

SYMMETRIC DEVELOPMENT OF MESO DISTURBANCE UNDER EFFECT OF NONZONAL BASIC FLOW

用ｆ平面非静力平衡滤声波模式，在自然坐标系下，运用ＷＫＢＪ方法及能量方法研究了非平直基流对中尺度扰动波包发展问题。结果表明：中尺度波包对称发展主要取决于扰动波结构与背景场结构之间的匹配。当基流为平直气流时，波包发展取决于背景场非热成风空间分布的不均匀性；当基流为弯曲气流时，波包发展取决于非梯度风平衡下的非热成风空间分布不均匀性。研究还表明。

Effects of nonzonal basic flow on meso disturbance wave ensemble are investigated in terms of an f plane nonhydrostatic balance acoustic wave filtering model in natural coordinates through WKBJ and energetic schemes. It turns out that the symmetric evolution of the wave packet depends strongly on the matching in structure of the perturbation and background field; as the basic flow is zonal (curved) the development is related to the inhomogeneous distribution of nonthermal wind in the environmental field with the balance of nongradient wind. Further analysis shows that the wave ensemble development is relevant to the curvature vorticity of thermal wind in the background field.