Warm Season Convective Weather Systems over the Great Lakes and Vicinity

本研究的重点是继续研究主要在暖季发生在五大湖附近的有组织对流天气系统。具体来说，研究的目标是中尺度对流系统（MCS）和嵌入式中尺度对流涡旋（MCV），以及强准线性对流系统被称为脱回波。在实际多普勒雷达图像中，回波常表现为弯曲线段。弓形回波和中尺度对流涡旋实验（BAMEX）的主要焦点是大回声和中尺度对流涡旋。这项研究建立在BAMEX的机会之上。具体研究任务包括：1)建立与MCV和触发上层扰动相关的涡度场在深层对流开始后如何重组和向上扩展；2)评估MCS/derecho生命周期对触发上层强迫扰动结构和地表边界（预先存在的和对流驱动的）相互作用程度的敏感性；3)利用现有的更高时空分辨率网格数据集，通过新的诊断分析研究MCV/MCS/derecho结构和生命周期。4)采用最先进的天气研究与预报（WRF）模式模拟MCV生命周期，并将MCV发展与早期热带气旋发展进行比较。5)对真实的和理想化的MCS/derecho事件进行WRF模型模拟，以评估在什么时候大尺度强迫变得不重要，风暴尺度动力学何时成为主导因素；6)扩大正在进行的研究工作，旨在更好地理解五大湖暖季恶劣天气（对流）事件的物理机制。业务预报中心提供的高分辨率、全球网格化分析将促进这项研究。来自NOAA区域更新周期（RUC）系统的网格化13公里分析也将发挥优势。北美地区每小时地面和高空RUC分析的可用性将允许对长寿命mcv和derechos的生命周期进行调查。这些分析与特殊的BAMEX数据集和WRF模式的模拟相结合，将允许通过多尺度案例研究对重要的对流天气事件进行比以前更全面的研究调查。就更广泛的影响而言，现有的天气预报模式在正确模拟对流模式和生命周期方面做得相对较差。在这方面，可操作的天气预报模型在预测恶劣天气的能力方面是有限的。这项研究的结果将增加对恶劣天气事件的新认识。在这个项目下训练和支持的研究生将有助于他们在毕业后从事该领域的职业时将研究知识转移到业务中。该项目还提供了与各种政府机构（例如，NOAA风暴预测中心）和其他教育机构合作的机会，以帮助促进研究知识向业务和学生的转移。

The focus of this research is on continued studies of organized convective weather systems that occur primarily during the warm season in the vicinity of the Great Lakes. Specifically, the research is targeted at mesoscale convective systems (MCS) and embedded mesoscale convective vortices (MCV) as well as intense quasi-linear convective systems know as derechos. Derechos often appear as bowing line segments in operational Doppler radar imagery. Derechos and MCVs were the major focus of the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). The research builds on opportunities from BAMEX. Specific research tasks include: 1) establish how the vorticity fields associated with the MCV and the triggering upper-level disturbance reorganize and scale upward after deep convection begins, 2) assess MCS/derecho life cycle sensitivity to the structure of the triggering upper-level forcing disturbances and the extent of surface boundary, pre-existing and convectively driven, interactions, 3) investigate MCV/MCS/derecho structure and life cycles through new diagnostic analyses that take advantage of available higher spatial and temporal resolution gridded datasets 4) employ the state-of-the-art Weather Research and Forecasting (WRF) model to simulate MCV life cycles and compare MCV development with incipient tropical cyclone development, 5) perform WRF model simulations of real and idealized MCS/derecho events to assess at what point larger scale forcing becomes unimportant and when storm-scale dynamics becomes dominant, and 6) expand an ongoing research effort targeted at developing a better understanding of the physical mechanisms that govern warm season severe weather (convection) events that occur over the Great Lakes. The research will be facilitated by the availability of high resolution, global, gridded analyses from operational forecast centers. Advantage will also be taken of the gridded 13 km analyses form the NOAA Regional Update Cycle (RUC) system. The availability of hourly surface and upper air RUC analyses over North America will permit an investigation of the life cycles of long-lived MCVs and derechos. These analyses when coupled with the special BAMEX datasets and simulations from the WRF model will permit more comprehensive research investigations of important convective weather events through multiscale case studies than has been previously possible. In terms of broader impacts, existing weather prediction models do a relatively poor job of simulating convective mode and life cycles properly. In this regard, the operational weather prediction models are limited in how well they can forecast severe weather. The results from the research will add to new knowledge of severe weather events. The graduate students trained and supported under this project will facilitate the transfer of research knowledge to operations as they pursue careers in the field after graduation. This project also presents the opportunity to work with various government agencies (e.g., the NOAA Storm Prediction Center) and other educational institutions to help facilitate the transfer of research knowledge to operations and students.