The Spectrum of Gravity Waves Radiating from Tropical Cyclones with Observations, Simulations, and Theoretical Modeling

热带气旋核心的深层湿对流产生重力波，这些重力波呈螺旋状向外辐射。 在距离真实的风暴数百公里的地面和飞机观测中，这些波的证据已经清楚地呈现出来。 该项目将研究这些波，重点是确定眼壁区域的哪些物理过程负责产生主导（和最可观测的）波。 这项研究还将探讨波的频率和振幅与风暴强度或强度变化的相关程度。学术成果：对大气对流和TC动力学的理论理解要求热带气旋辐射重力波;这些在卫星图像中越来越频繁地可见。 一些研究已经考虑了这些波是否在TC的角动量或能量收支中起作用，或者在雨带的形成和传播中起作用，但大多数结果要么是否定的，矛盾的，或不确定的。随着近年来计算机能力和数据存储量的增加，数值模拟可以定期进行，形成1公里的网格间距和2分钟的输出。在这些模拟的垂直风场中，可以清楚地看到辐射重力波的场，同时具有几个不同的径向波长和垂直结构。 功率谱分析的模拟时间序列的表面压力和表面风速表明，这些波也可以检测到从固定的表面仪器。沿着全物理模拟的输出，将使用大气中涡旋动力学的线性模型来探索眼壁中的对流和/或涡旋动力学与辐射波的特性之间的关系。此外，在太平洋上，当台风在几百公里外经过时，通过仪器对压力和风的高频观测，可以看到同样的波浪的证据公里，以及NOAA研究飞机的飞行高度数据。这些初步结果需要更广泛的调查，以了解TC强度，TC的运动，以及它们的辐射重力波的频率和振幅之间的关系。更广泛的影响：这项研究将进一步扩展我们对热带气旋眼壁区域的物理和动力学过程的理解，在那里，热能被转换为更广泛的风场的动能。该研究还将确定数值模拟中产生的波浪与观察到的波浪之间的差异。了解这些差异可以改善飓风预报模型及其强度预测，最终造福社会。这项工作将寻求确定TC强度，TC运动和辐射波特性之间的独特关系，这些特性已经在距离风暴中心数百公里的地面观测中发现。 该项目将进一步推进我们的方法，使用社区模型（WRF），允许用户模拟不同强度和大小的TC。高频模式输出将提供给社区，并可用于研究其他物理过程。该项目将支持一名博士后和一名研究生的培训。

The deep moist convection in the cores of tropical cyclones (TCs) generates gravity waves which are seen radiating outwards in trailing spiral patterns. Evidence for these waves have been clearly presented in surface and aircraft observations hundreds of kilometers from real storms. This project will investigate these waves, with a focus on determining which physical processes in the eyewall region are responsible for generating the dominant (and most observable) waves. The research will also explore the extent to which the wave frequencies and amplitudes can be correlated with intensity or intensity changes of the storm.Intellectual Merit:Theoretical understandings of atmospheric convection and TC dynamics require that tropical cyclones radiate gravity waves; these are becoming more and more frequently visible in satellite images. A number of studies have considered whether these waves play some role in the angular momentum or energy budgets of TCs, or in the formation and propagation of rainbands, but most results have been either negative, contradictory, or inconclusive. With recent increases in computer power and data storage, numerical simulations can be regularly per- formed with 1-km grid spacing and 2 minute output. The field of radiating gravity waves, with several different radial wavelengths and vertical structures simultaneously, can be clearly seen in the vertical wind fields of these simulations. Power spectral analyses of simulated time series of surface pressure and surface wind speed suggest these waves can also be detected from fixed surface instruments. Along with the output of full-physics simulations, a linear model of vortex dynamics in the atmosphere will be used to explore the relationships between convection and/or vortex dynamics in the eyewall and the properties of the radiating waves.Furthermore, evidence for these same waves were seen in high frequency observations of pressure and wind from instruments in the Pacific ocean during the passage of typhoons at distances of several hundred kilometers, and also in flight level data from NOAA research aircraft. These preliminary results call for a broader investigation to understand the relationships between TC intensity, TC motion, and the frequencies and amplitudes of their radiating gravity waves.Broader Impacts:The research will further extend our understanding of physical and dynamical processes in the eyewall regions of tropical cyclones, where heat energy is converted into the kinetic energy of the broader wind field. The research will also identify differences between the waves produced in numerical simulations and observed waves. Understanding these differences can lead to improvements in hurricane forecast models and their intensity predictions, which ultimately benefit the society. This work will seek to identify distinct relationships between TC intensity, TC motion, and the properties of the radiating waves, which are already found to be observable in surface observations hundreds of kilometers from the storm center. This project will further advance our methods using a community model (WRF) that allows user to simulate TCs of different intensities and sizes. The high-frequency model output will be made available to the community, and could be used to study other physical processes. The project will support the training of a post-doc and a graduate student.