Improving our Understanding of Tornadic Storms using VORTEX2 Observations and Idealized Simulations

使用 VORTEX2 观测和理想化模拟提高我们对龙卷风的了解

• 批准号: 1536460
• 负责人: Yvette Richardson
• 金额: $ 90万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536460&HistoricalAwards=false
• 关键词: Improving; our; Understanding; Tornadic; Storms

This research is targeted to improve our understanding of the processes occurring within supercell thunderstorms that control the development of rotation at the surface, its possible intensification, and the evolution of the circulations thereafter using state-of-the-art observations from the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) and a hierarchy of numerical models. The generation of midlevel rotation in supercell storms is well understood, but there are a number of outstanding questions pertaining to the development of rotation at low levels and the subsequent intensification of that rotation to tornado strength.The main objectives of this research are- To examine how low-level circulation in supercells is controlled by the storm environment and buoyancy of the outflow- To investigate how environmental heterogeneity and storm interactions influence the development and evolution of low-level rotation- To determine how surface friction affects the development of near-surface vertical vorticity- To explore the origins of small-scale outflow "surges" and descending precipitation shafts on the supercell's rear flank and their influence on the development and evolution of low-level rotationIntellectual Merit:Despite having a good grasp of how vertical wind shear and instability in a storm's environment promote updraft rotation, scientists still lack a thorough understanding of how many other aspects of a storm's environment, including environmental heterogeneity, influence the development and maintenance of low-level rotation in supercell storms. Even less is known about how storm interactions, sudden precipitation impulses, and outflow surges affect low-level rotation. Moreover, scientists are just now scratching the surface on how surface friction might be an important source of angular momentum for developing tornadoes (as opposed to simply playing an "indirect" role in tornadogenesis by enhancing near-surface convergence of angular momentum that arises through other means).Broader Impacts:A greater understanding of tornado genesis, maintenance, and demise will have a broad impact on our ability to predict and warn of these severe weather events and to reduce casualties. The migration of National Weather Service (NWS) warning issuance from counties to more flexible polygons now affords the opportunity to tailor the size of the warning (and, implicitly, the duration of the warning) to the expected longevity of the tornado. This research may help improve the guidance that can be used by forecasters to anticipate how long a tornado might last. In addition to communicating findings to the academic community at conferences, both PIs have been directly involved with the transfer of new knowledge to the NWS via seminars. Both PIs also have been active in a wide range of outreach activities, including briefing the Congressional Natural Hazards Caucus, briefing the National Academies Board on Atmospheric Sciences and Climate, serving as science advisers for an IMAX film on tornadoes, developing K-12 educational materials, giving talks to nonscientist groups (e.g., elementary schools, storm spotters, etc.), and developing museum exhibits.

这项研究的目的是利用第二次龙卷风旋转起源验证实验(VORTEX2)的最新观测和一系列数值模式，改善我们对超级单体雷暴内发生的过程的理解，这些过程控制着地表旋转的发展，它可能的加强，以及此后环流的演变。超级单体风暴中中层自转的产生是众所周知的，这项研究的主要目的是：研究超级单体中的低层环流是如何受风暴环境和外流浮力控制的；环境的非均质性和风暴的相互作用如何影响低层旋转的发展和演变；地面摩擦如何影响近地面垂直涡度的发展；探索超级单体后侧的小范围外流“涌浪”和下降的降水井的起源及其对发展的影响和低层旋转的演变智力上的优点：尽管很好地掌握了风暴环境中的垂直风切变和不稳定如何促进上升气流旋转，科学家们仍然缺乏对风暴环境的其他许多方面，包括环境异质性，影响超级单体风暴中低水平旋转的发展和维持的透彻了解。关于风暴相互作用、突然的降水脉冲和外流涌动如何影响低层旋转的了解就更少了。此外，科学家们还在探索表面摩擦如何可能成为龙卷风发展的角动量的重要来源(而不是简单地通过加强通过其他方式产生的角动量在近地表汇聚来在龙卷风发生中发挥“间接”作用)。更广泛的影响：对龙卷风的发生、维持和消亡的更多了解将对我们预测和警告这些恶劣天气事件和减少伤亡的能力产生广泛的影响。美国国家气象局(NWS)的警报发布从县迁移到更灵活的多边形，现在提供了根据龙卷风的预期寿命调整警报大小(以及隐含的警报持续时间)的机会。这项研究可能有助于改进预报员预测龙卷风可能持续多长时间的指导。除了在会议上与学术界交流研究结果外，这两家私人投资机构还通过研讨会直接参与向国家工作人员传授新知识。这两家私人投资机构还积极参与了广泛的外联活动，包括向国会自然灾害核心小组通报情况、向国家科学院大气科学和气候委员会通报情况、担任一部有关龙卷风的IMAX电影的科学顾问、开发K-12教育材料、为非科学家团体(如小学、风暴观测员等)举办讲座，以及开发博物馆展品。