Fundamental Lower Tropospheric Processes in Observed and Simulated Supercells

超级单体（长寿命的旋转雷暴）对我们的社会有很大的影响，造成了绝大多数的龙卷风和巨大的冰雹，也经常产生强烈的局部降雨和破坏性的非龙卷风风。最近的气候学和过程研究表明，冷池（外流）特性、对流层低层垂直风切变和对流层低层稳定性是超级单体维持和龙卷风形成等过程的基础。然而，真正的“因果关系”仍然难以捉摸，因为仍有许多未知的物理联系。这种知识的缺乏是很重要的，因为如果没有它，预测和及时发出超级细胞危害警报（并避免误报）的能力就不太可能得到改善。本研究旨在通过继续我们对基本超级单体过程的假设驱动研究来解决知识库中的空白。本研究包括对最近收集的来自旋转起源验证实验2 （VORTEX2）的数据的分析，以及由这些测量引起的数值模拟和与这些测量的比较。本应用程序的目的是分析龙卷风和非龙卷风超级单体的对流层低层流出过程和风暴环境反馈。为了实现这一应用的目标，该项目将追求三个具体目标：1)解释在超级单体下产生表面涡度的下沉气流过程；2)确定低层垂直风切变与低层稳定性在超级单体维持或消亡中的相对重要性；3)确定超级单体产生的近风暴环境变化。本研究直接解决了VORTEX2的三个科学焦点：龙卷风形成，超级单体风暴及其环境之间的关系，以及风暴尺度的数值天气预报。这项研究具有创新性，因为它利用了前沿的VORTEX2数据集来弥补知识库中的空白，而且它提出了一些关于超级细胞表面涡度产生的新假设。这项工作的成果将包括对超级单体低层过程的深入了解，包括与龙卷风形成、风暴维持和风暴-环境相互作用相关的动力学。预计这项研究意义重大，因为它将为威胁公民生命和财产的严重风暴提供更多的见解。更广泛的影响考虑到VORTEX2活动的大量初始公共资金支出，继续支持对VORTEX2数据的分析是一项充分利用的投资。面对2011年创纪录的龙卷风死亡人数，超级单体和龙卷风预报和预警的进步将符合公众利益。该项目将为研究生和博士后提供培训和指导。PI还继续将VORTEX2的数据和结果纳入他的日常课程。实验的高知名度和前所未有的数据集使结果对学生极具吸引力。私家侦探还一直致力于让代表性不足的群体参与他的研究和实地工作。PI同意无限制地与社区共享VORTEX2移动测深数据，并致力于帮助社区充分利用这些数据。除了常规的会议和期刊文章之外，PI还将与国家气象局的业务预报员进行互动，教授业务短期课程，并就VORTEX2发表公开研究演讲。

Supercells (long-lived rotating thunderstorms) have great impact on our society, accounting for the vast majority of tornadoes and very large hail, and also often producing intense local rainfall and damaging non-tornadic winds. Recent climatologies and process studies have revealed that cold pool (outflow) properties, lower tropospheric vertical wind shear, and lower tropospheric stability are fundamental to processes such as supercell maintenance and tornadogenesis. However, true "cause and effect" remains elusive because there are still a number of unknown physical links. This lack of knowledge is important because, without it, the ability to forecast and produce timely warnings (and avoid false alarms) for supercellular hazards is unlikely to improve. This research seeks to address gaps in the knowledge base by continuing our hypothesis-driven research on fundamental supercell processes. This study includes both analyses of recently-collected data from the Verification of the Origins of Rotation Experiment 2 (VORTEX2), as well as numerical simulations that are motivated by and compared to those measurements.The goal of this application is to analyze the lower tropospheric outflow processes and storm-environment feedbacks in tornadic and non-tornadic supercells. To accomplish the goal of this application, the project will pursue three specific objectives: 1) explain the downdraft processes that produce surface vorticity beneath supercells; 2) establish the comparative importance of low-level vertical wind shear vs. low-level stability in the maintenance or demise of supercells; and, 3) identify the near-storm environmental modifications produced by supercells.Intellectual Merit This study directly addresses three of the VORTEX2 scientific foci: tornadogenesis, relationships between supercell storms and their environments, and storm-scale numerical weather prediction. The research is innovative because it exploits the cutting edge VORTEX2 dataset to attack gaps in the knowledge base, and because it addresses a number of novel hypotheses for production of surface vorticity in supercells. The outcomes of this effort will include advanced understanding of low-level processes in supercells, including dynamics associated with tornadogenesis, storm maintenance, and storm-environment interactions. The research is expected to be significant, because it will provide additional insight into severe storms that threaten citizens' lives and property.Broader impactsGiven the considerable initial outlay of public funds for the VORTEX2 campaign, continued support for analysis of VORTEX2 data is a well-leveraged investment. In the face of 2011's historic number of tornado fatalities, advances in supercell and tornado forecasting and warning would be in the public interest.This project will support training and mentoring for graduate students as well as a postdoc. The PI also continues to incorporate data and results from VORTEX2 into his routine courses. The high profile of the experiment and unprecedented datasets make the results extremely appealing to students. The PI also has an ongoing commitment to involving underrepresented groups in his research and field work. The PI agrees to restriction-free share VORTEX2 mobile soundings data with the community, and is committed to helping the community fully exploit those data. In addition to the routine venues of conferences and journal articles, the PI will interact with operational forecasters from the National Weather Service, teach operational short courses, and present public research talks on VORTEX2.