Collaborative Research: Damage Analysis and Numerical Simulation of Convectively Driven Wind Events Observed during the Bow Echo and Mesoscale Vortex Experiment (BAMEX)

弓形回声被认为是地面上严重的、但主要是非龙卷风破坏的多产风暴。普遍接受的破坏性风的解释涉及到强烈的地表冷池和相关的后方流入急流(Rij)，后者下降到船头尖端后面的地面。最近的理想化数值模拟和有限的观测提出了一种不同的模型，在该模型中，破坏性的地面风也是在顶点以北数十公里处由低层中伽马尺度(直径约10公里)的垂直涡旋引起的。模拟表明，在某些条件下，中涡旋风可能比顶端的Rij风更强、持续时间更长，并产生更大的显著破坏区域。验证这一新解释的充分观察还有待收集。此外，在弓形回波的中尺度环境明显不均匀的情况下，这种破坏性风产生机制的普遍性还有待确定。这项研究的主要目的是：(I)对弓形回波事件后的风损害进行详细的空中和地面调查，将损害雷达观测到的对流系统位置和结构特征的严重程度和规模联系起来；(Ii)对弓形回波事件进行分析和中尺度模式模拟，以研究破坏性风、中尺度涡旋和对流系统结构对非均匀中尺度环境的依赖关系。弓回波和中尺度对流涡旋(MCV)实验(BAMEX)将为拟议的工作提供框架。BAMEX试图了解和改进对以下方面的预测：弓形中尺度对流系统内导致地面破坏性风的中尺度和细胞尺度过程；以及它们经常引发的MCV和深层积云对流。BAMEX将在以密苏里州圣路易斯为中心的一个大型试验区内进行，并将通过专门的空中和地面观测平台进行前所未有的数据收集。事件后损害调查是BAMEX数据集的关键组成部分，将根据本奖项进行，并用于满足本奖项以外的众多BAMEX目标。这项研究的结果将极大地澄清对船头回波中破坏性风产生的理解，并将阐明最有可能发生破坏性风的地方，具有哪些雷达可观测属性，以及在什么中尺度环境条件下。最终，业务预报员可以将结果应用于发布更及时、更准确的破坏性非龙卷风地面风的预报和警告。

The bow echo is known as a prolific producer of severe, though primarily non-tornadic, wind damage at the ground. The generally accepted explanation for the damaging wind involves a strong surface cold pool and associated rear-inflow jet (RIJ) that descends to the ground behind the apex of the bow. Recent idealized numerical simulations and limited observations are suggesting a different model, in which damaging surface winds are also induced tens of kilometers north of the apex by low-level, meso-gamma scale (order 10 km diameter) vertical vortices. Simulations suggest that, under certain conditions, mesovortex winds can be stronger, have longer durations, and produce a larger area of significant damage than can the RIJ winds at the apex. Adequate observations to validate this new explanation have yet to be collected. Further, the generality of this damaging-wind producing mechanism has yet to be established in instances when the mesoscale environment of the bow echo is significantly inhomogeneous. Underscoring the importance of this are recent observational studies that indicate a relation between reports of damaging straight-line (and/or tornadic) winds and the interaction of a bow echo and mutually perpendicular "external" outflow boundary.The primary objectives of this research are to: (i) conduct detailed aerial and ground surveys of wind damage following bow echo events, relating the severity and scale of damage to radar-observed convective system location and structural characteristics; and (ii) perform analyses and mesoscale model simulations of bow echo events in order to investigate dependencies of damaging winds, meso-vortexgenesis, and convective system structure on the inhomogeneous mesoscale environment. The bow echo and mesoscale convective vortices (MCV) experiment (BAMEX) will provide the framework for the proposed work. BAMEX seeks to understand and improve prediction of: the meso- and cellular-scale processes, within bow-shaped mesoscale convective systems, that lead to damaging winds at the ground; and MCVs and the deep cumulus convection they often trigger. BAMEX will be conducted over a large experimental domain centered on St. Louis, Missouri, and will involve unprecedented data collection via specialized airborne and ground-based observing platforms. Post-event damage surveys, a critical component of the BAMEX dataset, will be conducted under this award and used to meet numerous BAMEX objectives beyond those to be addressed under this award.The results of this research will significantly clarify the understanding of damaging wind production in bow echoes and will illuminate where the most damaging winds are most likely to occur, with what radar-observable attributes, and under what mesoscale environmental conditions. Ultimately, results may be applied by operational forecasters to issue more timely and accurate forecasts and warnings of damaging nontornadic surface winds.