Development of Unmanned Aircraft System and Its Use in Investigating the Impact of Pre-Existing Airmass Boundaries on Supercell Rotation

智力价值：该项目的目的是开发和利用无人驾驶飞机系统(UAS)，以获得在强雷暴附近高空的关键气象观测。这是一个探索性项目，最初的重点是系统开发和在严重风暴环境中使用这种系统的经验。然后，无人机将被用来在第二次龙卷风旋转原点验证实验(涡旋2)期间收集数据。对先前存在的气团边界对超级单体旋转的影响的研究是涡旋2目标的重要组成部分。在第一次涡旋期间所作的观察清楚地揭示了先前存在的气团边界(不是由风暴本身产生的边界)在增强超级单体旋转方面可以发挥的重要作用。然而，关于超细胞-边界相互作用的确切性质，还有许多悬而未决的问题。到目前为止，这些问题实际上仍然无法回答，主要是因为表面上的热力学测量不足。气团边界可以是水平涡度增强、对流可用势能增强和动力驱动上升运动的局部区域。这些特性中的每一个都可能影响超级细胞的旋转。这些实验的具体目的是量化这些性质，以确定1)水平涡度和2)动力/热力学驱动的垂直运动如何影响与先前存在的气团边界相互作用的超级单体的旋转。回答这些问题所需的分析需要通过对气团边界和附近风暴的热力学和运动学特性进行协调观测来收集数据。在之前处理超级单体和龙卷风的野外项目中收集的数据不足以进行这种分析。然而，在涡旋2中的观测可能会提供一个收集这些协调数据的独特机会。分析需要预先存在的边界和附近风暴的四维(4D)风场，以及这些边界上的温度和湿度场。在涡旋2中，将使用多个多普勒雷达来反演4D流场，并将利用所开发的无人机和移动中网车来反演气团边界的详细热力学结构。更广泛的影响：这项工作将刺激和支持先进仪器的发展。更好地了解超级单体旋转将如何对特定的风暴边界相互作用做出反应，将通过更好地预测龙卷风的发生，潜在地造福社会。

Intellectual Merit: The purpose of this project is to develop and utilize unmanned aircraft systems (UAS) to obtain critical meteorological observations aloft in the vicinity of severe thunderstorms. This is an exploratory project with the initial emphasis being on the system development and obtaining experience in utilizing such systems in severe storm environments. The UAS will then be used to collected data during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX 2). An examination of the impact of pre-existing airmass boundaries on supercell rotation serves as an important component of the VORTEX 2 objectives. Observations made during the first VORTEX clearly revealed the significant role that preexisting airmass boundaries (boundaries that are not generated by the storm itself) can play in the enhancement of supercell rotation. However, there are many unanswered questions regarding the precise nature of supercell-boundary interactions. These questions have so far remained virtually unanswerable largely due to insufficient thermodynamic measurements above the surface. Airmass boundaries can be localized regions of enhanced horizontal vorticity, enhanced convective available potential energy, and dynamically-driven upward motion. Each of these properties could impact supercell rotation. The specific aim of the experiments is to quantify these properties in order to determine how 1) horizontal vorticity and 2) dynamically/thermodynamically-driven vertical motion impact the rotation of a supercell interacting with a preexisting airmass boundary. The analysis required to answer these questions requires data collected through coordinated observations of both the thermodynamic and kinematic properties of airmass boundaries and nearby storms. Data collected during previous field programs dealing with supercells and tornadoes are insufficient to enable this analysis. However, observations in VORTEX 2 potentially will provide a unique opportunity to collect these coordinated data. The analysis requires four dimensional (4D) wind fields of preexisting boundaries and nearby storms as well as the temperature and moisture fields across these boundaries. In the VORTEX 2, the 4D flow fields will be retrieved with multiple Doppler radars and the detailed thermodynamic structure of airmass boundaries will be retrieved using the developed UAS and a mobile mesonet vehicle. Broader Impacts: This work will stimulate and support the development of advanced instrumentation. Better understanding of how supercell rotation will respond to a specific storm-boundary interaction potentially will benefit society through better forecasts of tornado genesis.