Numerical and Observational Studies of Tornadic Supercells

虽然在过去十年中在了解龙卷风及其母风暴的动态方面取得了进展，但关于导致龙卷风发生的因素以及控制任何特定龙卷风的强度和寿命的因素，仍有许多未知之处。在这项研究中，首席调查员将调查大范围环境条件(例如风切变和浮力)如何控制超级单体雷暴中龙卷风的强度和寿命。这项工作建立在首席调查员之前关于超级单体雷暴内低层旋转和龙卷风形成的研究的基础上，也是对这一研究的合乎逻辑的后续。首先，首席调查员目前的研究将扩展到龙卷风的规模，以努力促进对龙卷风成因的了解。先前的工作已经导致了对Rotunno和Klemp范式的改进，以确定超级细胞中低水平旋转的起源。主要研究者的新理论证明了流入环境的近地面水平涡度对中气旋发生的动力作用，并可用于预测近地面垂直风切变廓线，这是在超级单体内产生强低层中气旋的最佳条件。这项工作的扩展包括研究龙卷风尺度环流是否与中气旋环流直接相关，以及一项研究，以了解切变和浮力在决定龙卷风生成所需的低层环流和辐合的空间尺度和级别中的作用。第二，将尝试对在龙卷风旋转起源验证实验中观察到的特定超级单体和龙卷风进行显式模拟。这部分研究将对云模拟真实感的现状提供亟需的评估，并有望确定对流尺度模拟需要改进的具体方面。这项研究的潜在好处很多。除了增加对风暴和龙卷风动力学的基本了解外，运营界还将从这项研究中受益。了解哪些特定的风切变、温度和湿度的环境轮廓对龙卷风最具传导性，将使业务预报员能够精确定位并专注于有利于形成强烈龙卷风风暴的小区域。通过更充分地了解这些超级单体及其龙卷风的相关动力学，改进的恶劣天气预报和多普勒雷达观测可以更有效地用于预测和检测龙卷风的形成，并向公众发出警告。

While progress has been made over the last decade on understanding the dynamics of tornadoes and their parent storms, much is still unknown concerning the factors that cause tornado genesis and that control the intensity and longevity of any given tornado. In this research, the Principal Investigator will investigate how the large scale environment conditions (e.g. wind shear and buoyancy) control the intensity and longevity of tornadoes within supercell thunderstorms. This work builds on and is a logical follow-up to the Principal Investigator's previous research on the development of low-level rotation and tornado genesis within supercell thunderstorms.Two separate lines of research will be pursued. First, the Principal Investigator's current research will be extended down to the tornado scale in an effort to advance understanding of tornado genesis. The previous work has resulted in refinements to the Rotunno and Klemp paradigm for origins of low-level rotation in supercells. The Principal Investigator's new theory demonstrates the dynamical role the inflow environment's near-surface horizontal vorticity has on mesocyclogenesis and can be used to predict the near-surface vertical wind shear profiles which are optimal for the generation of strong low-level mesocyclones within supercells. Extension of this work includes examining whether tornado-scale circulations are directly related to the mesocyclone circulation, as well as a study to understanding the role of shear and buoyancy in determining the spatial scales and magnitude of the low-level circulation and convergence needed for the generation of tornadoes.Second, an attempt will be made to explicitly model a particular supercell and tornado observed during the Verification of Origins of Rotation in Tornadoes Experiment. This part of the study will provide a much needed evaluation of the current state of cloud simulation realism and hopefully identify specific aspects of convective scale modeling which need to be improved.Potential benefits from this research are many. Aside from increasing basic understanding of storm and tornado dynamics, the operational community will benefit from this research. Understanding which particular environmental profiles of wind shear, temperature and moisture that are most conductive for tornadoes will enable operational forecasters to pinpoint and focus on small regions where conditions are favorable for the formation of intense tornadic storms. By more fully understanding the dynamics associated with these supercells and their tornadoes, improved severe weather forecasts and Doppler radar observations can then be used more effectively to forecast and detect tornado formation and warn the public.