CMG: Analysis of Transport, Mixing, and Coherent Structures in Hurricane Intensity

该项目研究飓风动力学，特别强调通过混合来自不同来源的潮湿空气或干燥空气影响热带气旋强度的过程。 由于穿透风暴核心或眼壁是一个非线性混合问题，研究人员打算应用动力系统理论的方法，以帮助他们了解运输和混合过程，无论是在眼/眼壁系统的规模与眼壁中的中涡，以及整个涡旋的规模。 这项工作的部分动机是，现有的最大风强度理论，基于轴对称的假设，可以显着低估强度看到高分辨率的飓风数值模型。 眼壁中涡的形成和不对称地输送到飓风眼壁的湿空气的潜热释放可能有助于解释这种差异。要做的工作包括分析高分辨率飓风模拟的输出以确定不同的双曲线轨道及其稳定和不稳定流形，实施分析拉格朗日混合的新方法，找到飓风演变阶段的低维近似值，预计这一理论工作的结果将有助于设计未来的实地实验，有助于更好地了解飓风强度波动的过程，并为更好地预测飓风强度提供依据。

This project studies hurricane dynamics with a particular emphasis on processes that affect the intensity of the tropical cyclone by mixing in moist air or dry air from different sources. Since penetration to the storm core or eye-wall is a nonlinear mixing problem, the investigators intend to apply methods from dynamical systems theory to help them understand transport and mixing processes, both on the scale of the eye/eye-wall system with its mesovortices in the eye-wall, and on the scale of the vortex as a whole. Part of the motivation for this work is that existing theory for maximum wind intensity, based on assumptions of axisymmetry can significantly under-predict the intensities seen in high-resolution numerical models of hurricanes. The formation of eye-wall mesovorticies and latent heat release from moist air transported asymmetrically into the hurricane eye-wall may help explain this difference.The work to be done includes analyzing output from high-resolution hurricane simulations to determine distinguished hyperbolic orbits and their stable and unstable manifolds, implementing new methods for analyzing Lagrangian mixing, finding low-dimensional approximations to phases of hurricane evolution, and a search for a set of parameters that may be used to predict maximum wind intensity.It is anticipated that the results of this theoretical work will help in the design of future field experiments, contribute to a better understanding of the processes responsible for fluctuations in hurricane intensity, and provide a basis for better predictions of hurricane intensity.