Thermodynamics of Tropical Cyclone Overland Maintenance and Intensification

热带气旋陆上维持和强化的热力学

• 批准号: 1911671
• 负责人: Allen Evans
• 金额: $ 40.86万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1911671&HistoricalAwards=false
• 关键词: Thermodynamics; Tropical; Cyclone; Overland; Maintenance

The energy that fuels a tropical storm's or a hurricane's winds is typically drawn from warm ocean waters. However, for some tropical cyclones, the maximum surface winds have been observed to be maintained or even increase over land. A particularly noteworthy case is given by Tropical Storm Erin over Oklahoma, which dramatically and unexpectedly intensified into a strong tropical storm as it approached Oklahoma City from the west, resulting in millions of dollars of wind-related damage. The few prior investigations into this phenomenon generally agree that the required energy is drawn from the underlying land surface. However, they disagree on the extent to which the energy is associated with land warmth versus wetness, as well as on the physical processes that allow for a sufficient amount of energy to be concentrated near the surface so that it can be transferred to the tropical cyclones. Furthermore, the ideas advanced by these previous studies have generally been developed using highly simplified numerical weather prediction model simulations, with few instances in which these ideas have been tested for actual tropical cyclones. Consequently, this project seeks to significantly advance basic understanding of the energetics supporting tropical cyclone maintenance and strengthening over land while rigorously testing this understanding for a large sample of observed events. A partnership with the Ronald E. McNair Post-Baccalaureate Achievement Program at University of Wisconsin-Milwaukee will support the professional development and academic persistence of an undergraduate scholar from a traditionally underrepresented background, helping to increase representation of minority individuals within the workforce pipeline in the atmospheric and related sciences.This research tests three guiding hypotheses: remote surface energy exchange is the primary but not exclusive control on tropical cyclone intensity change over land; non-desert soils cannot be sufficiently warmed to result in sufficient upward enthalpy flux for tropical cyclone maintenance or intensification over land; and intensity change over land is equally sensitive to surface energy exchange and initial finite-amplitude atmospheric variability. Factor separation applied to idealized numerical simulations is used to test the first two hypotheses, whereas ensemble-initialized real-data simulations are used to test the applicability of the idealized simulation results to the real atmosphere. An expanded climatology of atmospheric and substrate properties associated with overland tropical cyclone maintenance and intensification is to support the numerical model simulations and advance knowledge of the environments in which these events occur. Through these activities, this research will reconcile competing theories regarding the thermodynamic processes necessary to support non- or weakly baroclinic tropical cyclone maintenance and intensification over land through quantifying the respective contributions of local and non-local land-surface energy exchange to overland tropical cyclone intensity change. Given the ongoing scientific debate regarding the surface latent heat flux magnitudes needed to permit tropical cyclone intensification over water, findings from the research will also advance knowledge of the energetics of the traditional overwater tropical cyclone intensification process.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

热带风暴或飓风的能量通常来自温暖的海洋沃茨。然而，对于一些热带气旋，观测到陆地上的最大地面风速保持不变，甚至有所增加。俄克拉荷马州上空的热带风暴艾琳（Erin）就是一个特别值得注意的例子，当它从西面逼近俄克拉荷马州城时，出人意料地急剧增强为强热带风暴，造成了数百万美元的风灾损失。对这一现象的少数先前调查通常同意，所需的能量是从下伏的陆地表面提取的。然而，他们对能量与陆地温暖和湿度的关系以及允许足够数量的能量集中在地表附近以便转移到热带气旋的物理过程存在分歧。此外，这些先前研究提出的想法通常是使用高度简化的数值天气预报模型模拟开发的，很少有实例表明这些想法已被实际热带气旋测试。因此，该项目旨在大大推进对陆地上支持热带气旋维持和加强的能量学的基本理解，同时严格测试对大量观测事件的这种理解。与罗纳德E. McNair Post-Baccalaureate Achievement Program at the University of Wisconsin-Milwaukee将支持来自传统代表性不足背景的本科学者的专业发展和学术坚持，帮助增加少数民族在大气和相关科学的劳动力管道中的代表性。这项研究测试三个指导假设：远距离地表能量交换是陆地上热带气旋强度变化的主要但非唯一控制因素;非沙漠土壤不能充分升温，从而产生足够的向上焓通量，使陆地上热带气旋得以维持或加强;陆地上的强度变化对地表能量交换和初始有限振幅大气变率同样敏感。应用于理想化数值模拟的因子分离用于测试前两个假设，而集合初始化的真实数据模拟用于测试理想化模拟结果对真实的大气的适用性。与陆地热带气旋维持和增强相关的大气和基质特性的扩展气候学是为了支持数值模式模拟和推进这些事件发生的环境知识。通过这些活动，本研究将调和相互竞争的理论，通过量化本地和非本地陆面能量交换对陆地热带气旋强度变化的各自贡献，来支持非斜压或弱斜压热带气旋在陆地上的维持和加强。鉴于目前关于允许热带气旋在水面上增强所需的表面潜热通量大小的科学辩论，该研究的结果也将促进传统水上热带气旋增强过程的能量学知识。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。