Collaborative Research: Using Polarimetric Radar Observations, Cloud Modeling, and In Situ Aircraft Measurements for Large Hail Detection and Warning of Impending Hail

冰雹是恶劣天气最危险和最具破坏性的表现之一，导致全球平均每年超过100亿美元的保险财产损失。除了对个人和商业财产的强烈冰雹影响外，农业和可再生能源部门也受到影响。先进的极化天气雷达是在云中远程探测冰雹、估计其大小并及时发出冰雹警告的最佳工具，如果以预测冰雹增长及其在地面上的散落的物理云模型为指导。然而，现有的量化和预报大冰雹的方法存在严重的局限性，该项目将缓解这些局限性。该项目将利用装甲T-28研究飞机对冰雹的独特观测，该飞机在过去的多次野外战役中穿透了冰雹风暴。将云中和地面上的直接冰雹测量与描述冰雹在到达地面途中演变的云模拟以及风暴全深度内的偏振雷达观测相结合，将有助于更好地了解冰雹产生的微物理过程，并为其量化和预报/现在预报开发更先进的方法。技术方法将涉及利用记录在案的对高空冰雹的大小、数量密度和形状的测量来初始化云模型。该模式涉及描述冰雹演变的光谱面元微物理，包括冰雹落到地面时冰雹大小和动能随高度的变化。云模型的输出将被转换成极化雷达变量的垂直剖面，并将其与相关的测量剖面进行比较。这将允许利用与融化层内和融化下的冰雹相关的雷达变量的垂直廓线来反演融化层以上的冰雹的尺寸分布，并将作为云模式评估和优化的观测参考。在深对流上升气流中预示着地表大冰雹或巨型冰雹的新型极化雷达预报器将使用在许多特别破坏性的冰雹天气中运行的WSR-88D雷达收集的极化雷达数据，在广泛的热力学和气候状况以及表面相对于海平面的高度上进行识别和探索。该奖项反映了NSF的法定任务，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Hail is one of the most dangerous and destructive manifestations of severe weather, resulting in an annual average of more than $10 billion USD in insured property losses around the world. In addition to the strong hail impact on personal and business property, the agricultural and renewable energy sectors also suffer. Advanced polarimetric weather radars are the best instruments to remotely detect hail in the clouds, estimate its size, and produce timely warnings of impending hail if guided by the physical cloud models that predict hail growth and its fallout on the surface. However, existing methodologies for quantifying and forecasting large hail have serious limitations which will be mitigated as a result of the project. This project will capitalize on the unique observations of hail from the armored T-28 research aircraft that penetrated hail-bearing storms during multiple field campaigns in the past. Combining direct hail measurements within the cloud aloft and at the surface with cloud modeling describing its evolution on the way to the ground and the collocated polarimetric radar observations within the full depth of the storm will help to better understand the microphysical processes of hail generation and develop more advanced methodologies for its quantification and prediction / nowcasting.The technical approach will involve utilization of the documented measurements of sizes, number concentrations, and shapes of hailstones aloft to initialize the cloud model. The model involves spectral bin microphysics describing the evolution of hailstones including the change of hail size and kinetic energy with height within the storm as they fall to the surface. The output of the cloud model will be converted into the vertical profiles of polarimetric radar variables which will be compared to the associated measured profiles. This will allow to retrieve size distribution of hail above the melting layer using vertical profiles of radar variables associated with melting hail within the melting layer and beneath and will serve as an observational reference for cloud models’ evaluation and optimization. Novel polarimetric radar predictors in deep convective updrafts signifying large or giant hail at the surface will be identified and explored across a wide range of thermodynamic and climatological regimes and height of the surface relative to sea level using polarimetric radar data collected by the operational WSR-88D radars in a multitude of particularly devastating hailstorms.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.