Numerical and Observational Studies of Tornadic Supercells

虽然在过去十年中，人们对龙卷风及其母风暴的动力学研究取得了进展，但对于导致龙卷风发生以及控制任何给定龙卷风强度和寿命的因素，仍有许多未知之处。 在这项研究中，首席研究员将研究大尺度环境条件（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研究员先前关于超级单体雷暴中低层旋转发展和龙卷风成因的研究的基础上，也是其逻辑上的后续研究。 首先，首席研究员目前的研究将扩展到龙卷风规模，以促进对龙卷风成因的理解。 以前的工作已经改进了Rotunno和Klemp范式，用于超级细胞中低水平旋转的起源。 首席研究员的新理论证明了流入环境的近地面水平涡度对中气旋生成的动力作用，并可用于预测近地面垂直风切变廓线，这对于在超级单体内生成强低空中气旋是最佳的。 这项工作的扩展包括检查龙卷风尺度环流是否与中气旋环流直接相关，以及研究了解切变和浮力在确定龙卷风生成所需的低层环流和辐合的空间尺度和大小方面的作用。将尝试对在龙卷风实验中旋转起源的验证期间观察到的特定超级单体和龙卷风进行明确的建模。 这部分的研究将提供一个非常需要的云模拟现实主义的当前状态的评估，并希望确定需要改进的对流尺度modeling的具体方面。 除了增加对风暴和龙卷风动力学的基本了解外，业务界将从这项研究中受益。 了解风切变、温度和湿度的哪些特定环境剖面最容易形成龙卷风，将使业务预报员能够精确定位并专注于条件有利于形成强烈龙卷风风暴的小区域。 通过更充分地了解与这些超级单体及其龙卷风相关的动力学，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警告公众。

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.