Improved understanding of bow echo evolution and long-lasting significantly severe thunderstorm winds

更好地了解弓形回波演变和持久的强雷暴风

• 批准号: 2350205
• 负责人: William Gallus
• 金额: $ 65.24万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-05-01 至 2027-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2350205&HistoricalAwards=false
• 关键词: Improved; understanding; bow; echo; evolution

Organized lines of thunderstorms, often known as squall lines or mesoscale convective systems, can produce large swaths of damaging winds. Two phenomena are particularly associated with high winds: bow echoes which are small segments embedded in a larger line that contain higher winds and seem to “bow” out ahead of the rest of the line, and derechos which are very long-lived lines which produce significant winds across a large area. This study will use fine resolution numerical modeling to investigate the processes that lead to bow echos and derechos. The high-impact nature of these events means that better understanding and the likelihood for better forecasting will have large dividends in terms of public safety and economic benefits. Additionally, students at various levels would be involved in the project, thereby training the next generation of scientists.The goal of this award is to improve understanding of the morphological evolution of mesoscale convective systems (MCSs), with an emphasis on bow echoes and the formation of significantly severe long-lasting wind associated with some of them (known as derecho events). The project will make use of the Weather Research and Forecasting (WRF) and Cloud Model 1 (CM1) numerical models to study various aspects of MCSs. In particular, the project will:• Examine the role of processes contributing to upscale growth in MCSs, particularly the strength of the temperature gradient at the leading edge of the cold pool, and contribution of gravity waves and direct lift at the leading edge of the cold pool, and their sensitivity to convection allowing model (CAM) grid spacing in simulations. • Examine the processes leading to bow echo formation, with emphasis on orientation of inflow, merger of lines with pre-existing cells, and presence of a boundary, and their sensitivity to CAM grid spacing.• Improve understanding of processes leading to long-lived significantly severe winds in MCSs, including the roles of features like the vertical position of dry air in the ambient environment, factors leading to intense mesoscale vortex formation in some cases, and whether such vortices are necessary for particularly strong, long-lived swaths of wind to form.• Study the impact of climate change on derecho events explored through the pseudo-global warming approach.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

有组织的雷暴线，通常被称为飑线或中尺度对流系统，可以产生大片破坏性大风，有两种现象与大风特别相关：弓形回波，它是嵌入包含更强风的较大线中的小片段。 “弓形”先于其他线，而 derechos 是非常长寿的线，会在大面积范围内产生显着的风。这项研究将使用高分辨率数值模型来研究导致弓形的过程。这些事件的高影响力意味着更好的理解和更好的预测将在公共安全和经济效益方面带来巨大的好处。此外，各个级别的学生都将参与该项目，从而获得培训。该奖项的目标是提高对中尺度对流系统（MCS）形态演化的理解，重点是弓形回波以及与其中一些系统相关的严重持久风的形成（已知作为derecho 事件）。该项目将利用天气研究和预报 (WRF) 和云模型 1 (CM1) 数值模型来研究 MCS 的各个方面，具体而言，该项目将： • 研究有助于升级的过程的作用。 MCS 的增长，特别是冷池前缘温度梯度的强度，以及冷池前缘重力波和直接升力的贡献，以及它们对对流允许模型（CAM）网格间距的敏感性模拟 • 检查导致弓形回波形成的过程，重点关注流入方向、线与预先存在的单元的合并、边界的存在以及它们对 CAM 网格间距的敏感性。• 提高对导致长回波的过程的理解。 - MCS中存在严重的强风，包括周围环境中干燥空气的垂直位置等特征的作用，在某些情况下导致强烈中尺度涡旋形成的因素，以及这种涡旋是否是特别强、寿命长的必要条件形成大片风。• 通过伪全球变暖方法探索气候变化对 derecho 事件的影响。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。