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

弓形回波被认为是一个多产的严重的生产者，尽管主要不是龙卷风，在地面上造成风害。普遍接受的对破坏性风的解释包括一个强大的表面冷池和相关的后流入射流（RIJ），它下降到弓形顶端后面的地面。最近理想化的数值模拟和有限的观测表明了一种不同的模式，在这种模式中，低层、中伽马尺度（直径约10公里）垂直涡旋也会在峰顶以北数十公里处引起破坏性的地面风。模拟表明，在某些条件下，中涡旋风比顶端的RIJ风更强，持续时间更长，造成的严重破坏面积更大。目前还没有足够的观测资料来证实这一新的解释。此外，当船首回波的中尺度环境明显不均匀时，这种破坏性风产生机制的普遍性还有待建立。最近的观测研究强调了这一点的重要性，这些研究表明，破坏性直线（和/或龙卷风）风的报告与弓形回波和相互垂直的“外部”流出边界的相互作用之间存在关系。本研究的主要目标是：(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，将损害的严重程度和规模与雷达观测到的对流系统位置和结构特征联系起来；（ii）对弓形回波事件进行分析和中尺度模式模拟，以研究破坏风、中涡形成和对流系统结构对非均匀中尺度环境的依赖关系。弓形回波和中尺度对流涡（MCV）实验（BAMEX）将为所提出的工作提供框架。BAMEX旨在理解和改进以下预测：在弓形中尺度对流系统中，中尺度和细胞尺度过程会导致地面上的破坏性风；mcv和它们经常引发的深积云对流。BAMEX将在以密苏里州圣路易斯为中心的一个大型实验区域进行，并将通过专门的机载和地面观测平台收集前所未有的数据。事件后损害调查是BAMEX数据集的一个重要组成部分，将根据该合同进行，并用于满足BAMEX的许多目标，而不是根据该合同解决的目标。这项研究的结果将大大澄清对弓形回波中破坏性风产生的理解，并将阐明最具破坏性的风最有可能发生在哪里，具有什么样的雷达可观测属性，以及在什么样的中尺度环境条件下。最终，结果可以应用于业务预报员，以发布更及时和准确的破坏性非龙卷风地面风的预报和警报。

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.