Collaborative Research: Basic Studies in Three-dimensional Tropical Cyclone Intensification

飓风是特别具有破坏性的热带天气系统，每年6月至11月期间威胁美国沿着大西洋海岸的人口中心。 发展良好的飓风在其核心区域显示出相对高度的几何组织，中心无云眼被近似的云环包围，称为眼壁，现有的飓风结构理论已经在轴对称环流的框架内利用了这种几何组织，这些方法为这种破坏性的飓风结构提供了有用的见解。现象 这个获资助的项目旨在更好地了解轴向不对称或“涡旋”过程在热带气旋增强中的作用。该研究项目将侧重于飓风中涡流过程的动力学和热力学，对热带风暴加强阶段的内部涡流过程进行综合、多管齐下的评估。具体来说，研究员会利用传统的欧拉分析和以拉格朗日相干结构为基础的新分析方法，进行诊断分析，以评估涡旋结构对热带风暴轴对称分量的影响。拉格朗日相干结构有助于识别风流内的结构，这些结构倾向于将气流分成不同的区域。这些区域将有助于确定涡流的动量和热量输送。 高分辨率的计算机模拟将是本研究的基础工具，并将研究在不同的计算机分辨率下分辨和分析重要涡旋的能力。 确定各种涡旋现象对平均飓风结构的多种作用具有很高的智力价值。 更好地描述涡旋对风结构和飓风强度的影响，将为今后制定参数化提供有益的指导。由于业务模式不能很好地解决这些精细尺度的特点，提高对涡旋过程对热带风暴迅速增强的重要性的认识，将有助于进一步提高预测飓风造成的重大危险的技能。

Hurricanes are especially destructive tropical weather systems that threaten population centers of the United States along the Atlantic coast between June and November every year. Well-developed hurricanes display a relatively high degree of geometrical organization in their core region, with a central cloud-free eye surrounded by an approximate ring of clouds, called the eyewall, where the most intense surface winds are found. Existing theories for hurricane structure have exploited this geometric organization in the framework of axial symmetric circulation and these approaches have provided useful insights into this destructive phenomenon. This funded project aims to gain a better understanding of the roles of axial asymmetries or "eddy" processes in the intensification of tropical cyclones. This research project will focus on the dynamics and thermodynamics of eddy processes in hurricanes using an integrated, multi-pronged evaluation of the internal eddy processes during the intensification stage of tropical storms. Specifically, the PIs will conduct diagnostic analyses to evaluate the impact of the eddy structures on the axial symmetric component of tropical storms by employing conventional Eulerian analyses and a new analysis method based on Lagrangian coherent structures. Lagrangian coherent structures help identify structures within the wind flow that tend to separate the flow into distinct regions. These regions will aid in the identification of momentum and heat transport by the eddies. High resolution computer simulation will be the foundational tool in this study, and the ability to resolve and analyze the important eddies at different computer resolutions will be investigated.This research is of interest to atmospheric science, fluid dynamics and dynamical system communities. The determination of the manifold roles of various eddy phenomena on the mean hurricane structure is of high intellectual merit. Improved characterization of the effects of eddies on the wind structure and intensity of hurricanes will serve as useful guidance in the development of future parameterizations. Since operational models do not well resolve these fine-scale features, the improved understanding of the importance of eddy processes for the rapid intensification of tropical storms would help further increase the skill in predicting the substantial hazard posed by hurricanes.