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The Impact of Ambient Deep-Tropospheric Vertical Wind Shear on Tornadoes and Their Attendant Supercells within Tropical Cyclones

环境深层对流层垂直风切变对热带气旋内龙卷风及其伴随超级单体的影响

基本信息

批准号：
2028151
负责人：
Benjamin Schenkel
金额：
$ 49.86万
依托单位：
University of Oklahoma Norman Campus
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-10-01 至 2024-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2028151&HistoricalAwards=false
关键词：
Impact Ambient Deep Tropospheric Vertical

项目摘要

Hurricane and tropical cyclone landfalls produce numerous hazards, from wind damage to flooding to storm surge. This project will address a lesser-studied aspect of tropical cyclone landfalls, tornadoes, and specifically the role of wind shear on their development. Tropical cyclone induced tornadoes are generally weaker than supercell tornadoes, but they are a public safety hazard. There is not a direct correlation between the strength of a tropical cyclone and the resulting number of tornadoes and forecast guidance is often generic. This award will provide a research-based understanding of tropical cyclone tornadoes which should allow operational weather forecasters to better alert the public of these hazards. The project will also involve multiple students as training for the next generation of researchers.The research team plans an analysis and modeling study of the role of vertical wind shear on the occurrence of tornadoes in landfalling tropical cyclones. Tornadoes frequently occur during hurricane landfall, but the number can vary by an order of magnitude among tropical cyclones that are otherwise of similar strength. These tornadoes are also much less predictable than the more common Great Plains tornadoes. This study will use observational analysis of the deep-tropospheric vertical wind shear and tropical cyclone-relative helicity from reanalysis data, other observations such as radar data and atmospheric soundings, and modeling with the WRF-based Warn on Forecast System (WOFS) to: 1) Test the variability of the relationship between tornadoes and deep convection in tropical cyclones and vertical wind shear with other relevant factors (e.g. diurnal cycle), 2) Assess the sensitivity of tornadic supercell predictability to vertical wind shear in hindcasts, and 3) Identify how vertical wind shear creates favorable environments for tropical cyclone tornadic supercells using observations and Lagrangian vertical vorticity budgets computed from hindcasts.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.

飓风和热带气旋的登陆会产生许多危害，从风灾到洪水再到风暴潮。这个项目将解决热带气旋登陆，龙卷风，特别是风切变在其发展中的作用研究较少的方面。热带气旋引发的龙卷风通常比超级单体龙卷风弱，但它们是一个公共安全隐患。热带气旋的强度和由此产生的龙卷风数量之间没有直接的相关性，预报指南通常是通用的。该奖项将提供基于研究的热带气旋龙卷风的理解，这应该允许业务天气预报员更好地提醒公众这些危险。该项目还将有多名学生参与，作为对下一代研究人员的培训。研究小组计划对垂直风切变在登陆热带气旋中龙卷风发生的作用进行分析和建模研究。飓风登陆时经常会出现龙卷风，但在强度相当的热带气旋中，龙卷风的数量可能会有一个数量级的差异。这些龙卷风也比更常见的大平原龙卷风更难预测。这项研究将利用再分析数据、雷达数据和大气探测等其他观测数据对深层对流层垂直风切变和热带气旋相对螺旋度进行观测分析，并利用基于WRF的预警预报系统（WOFS）进行建模，以便：1）测试龙卷风和热带气旋中的深对流与垂直风切变之间的关系与其他相关因素的变率（例如昼夜循环），2）评估龙卷风超级单体可预报性对后报中垂直风切变的敏感性，和3）的方法利用观测数据和后报计算的拉格朗日垂直涡度收支，确定垂直风切变如何为热带气旋龙卷风超级单体创造有利环境。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。