Collaborative Research: Supercell Left Flank Boundaries and Coherent Structures--Targeted Observations by Radars and UAS of Supercells Left-flank-Intensive Experiment (TORUS-LItE)

超级单体雷暴是美国大部分重大龙卷风的原因。然而，并不是所有的超级单体都会形成龙卷风，龙卷风警报的误警率居高不下。这场小型野外战役将使用各种仪器，包括雷达卡车和无人驾驶航空系统(UAS)来观测在超级单体左翼区域形成的大气边界。这个想法是，观察超级单体附近的小范围运动和边界将使我们更好地理解为什么一些超级单体形成龙卷风，而另一些则不形成。除了该项目的实际业务预测方面，实地活动将为15-20名学生提供参与数据收集的机会。这一奖项是为了表彰雷达和UAS对超级单体左翼密集实验(TOUS-LITE)的有针对性的观测，该实验是对超级单体雷暴左翼的特定过程及其与龙卷风发生的关系的观测研究。研究小组将于2023年5月和6月在大平原部署UAS、雷达、探空仪和移动中间网资产，为期三周，以直接对边界和相干结构进行采样。研究人员认为，要促进对超单体龙卷风发生与左/前侧翼边界和相干结构之间关系的理解，就需要横截面数据集，能够在超级单体/中气旋强度和近地表旋转的近距离演化的背景下描述这些边界和相关相干结构的结构和演变。要研究的科学问题是：a)左/前翼边界与增强的涡度重合的频率有多大，这种涡度的大小与相关边界和环境/环境状态的特征有何关系？B)伴随龙卷风风暴的流向涡度流(SVC)及其相关边界的特征与与非龙卷风风暴有关的特征是否有显著不同？C)左侧边界的密集侧气团能否被描述为密度流，SVC是否是随之而来的开尔文-亥姆霍兹(KH)巨浪？这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Supercell thunderstorms are responsible for the majority of significant tornadoes in the United States. However, not all supercells form tornadoes and the false alarm rate for tornado warnings is stubbornly high. This small field campaign will use a variety of instrumentation, including radar trucks and uncrewed aerial systems (UAS) to observe atmospheric boundaries that form in what is known as the left flank region of a supercell. The idea is that observing small scale motions and boundaries near supercells will allow us to better understand why some supercells form tornadoes while others do not. Beyond the practical operational forecasting aspect of this project, the field campaign will provide 15-20 students with the opportunity to participate in the collection of data. This award is for the Targeted Observations by Radars and UAS of Supercells Left-flank-Intensive Experiment (TORUS-LItE), an observational study of specific processes in the left flank of supercell thunderstorms and how they relate to tornadogenesis. The research team will deploy UAS, radar, sounding, and mobile Mesonet assets during a three-week period in May and June 2023 in the Great Plains to directly sample boundaries and coherent structures. The investigators believe that advancing understanding of the relationship between supercell tornadogenesis and left/forward flank boundaries and coherent structures requires cross-sectional datasets that enable characterization of the structure and evolution of these boundaries and associated coherent structures in the context of supercell/mesocyclone strength and proximate evolution of near-surface rotation. The science questions to be studied are: A) How often are left/forward-flank boundaries coincident with enhanced vorticity and how does the magnitude of this vorticity relate to the characteristics of the associated boundaries and environmental/ambient state? B) Do the characteristics of streamwise vorticity currents (SVCs) and associated boundaries attendant to tornadic storms differ significantly from those associated with non-tornadic storms? C) Can the dense-side airmasses of left-flank boundaries be characterized as density currents and are SVCs the attendant Kelvin-Helmholtz (KH) billows?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.