On the structure of concentrated atmospheric vortices in a gradient wind regime and its motion on synoptic scales
On the structure of concentrated atmospheric vortices in a gradient wind regime and its motion on synoptic scales
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梯度风况下集中大气涡的结构及其天气尺度运动
DOI：
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发表时间：
2007
期刊：
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通讯作者：
E. Mikusky
中科院分区：
文献类型：
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作者：
E. Mikusky
本文研究了垂直延伸到整个对流层、直径对应于次天气梯度风况的三维集中大气涡旋。类似飓风的涡旋是这类大气流动现象的典型例子。近年来的研究表明，作用于不同时间和长度尺度上的大气过程之间的复杂相互作用强烈地影响着类飓风涡旋的运动、结构和发展。众所周知，这些相互作用的过程是由地球自转、环境气流和小尺度对流系统引起的。正是在这样的背景下，本论文的目的是推导简化的模式方程，阐明尺度相互作用如何影响集中的大气涡旋的运动和结构。特别是，减少模型方程推导出描述中尺度结构的涡本身如何影响天气尺度涡运动，反之亦然，同时考虑到垂直剪切环境流和非绝热效应的影响，由于水分转换过程考虑。对于这种简化模型方程的推导，使用基于匹配渐近展开的多尺度渐近分析。由于各种原因，更好地理解决定大气涡旋运动和结构的机制是很有意义的。例如，在实际使用中，需要准确预报涡旋轨迹，以避免登陆风暴系统造成的潜在灾害。在这项工作中推导出的简化模型方程可以用来设计飓风路径模型，可能有助于改进飓风路径预报。
Three-dimensional concentrated atmospheric vortices with vertical extensions throughout the whole troposphere and diameters corresponding to the sub-synoptic gradient wind regime are studied in this work. Hurricane-like vortices are representative examples for this type of atmospheric flow phenomena. Research in recent years have shown that the complex interplay between atmospheric processes acting on different time and length scales strongly affect the motion, structure and development of hurricane-like vortices. It is well known that these interacting processes arise among others from the earth rotation, the environmental flow and small scale convective systems. It is against this background that this dissertation aims to derive reduced model equations that elucidate how scale interactions influence the motion and structure of concentrated atmospheric vortices. In particular, reduced model equations are derived that describe how the mesoscale structure of the vortex itself affects the synoptic scale vortex motion and vice versa, while taking the influence of a vertically sheared environmental flow and diabatic effects due to moisture conversion processes into account. For the derivation of such reduced model equations multiple scales asymptotic analysis based on matched asymptotic expansions are used. For various reasons a better understanding of the mechanisms determining the motion and structure of atmospheric vortices is of great interest. In operational use, for instance, an accurate forecast of the vortex trajectory is needed to avoid potential disasters caused by a landfalling storm systems. The reduced model equations derived in this work can be used to design hurricane track models that might contribute to improvements of hurricane track forecasts.