Enhanced Radar Studies of Severe Convective Storms and Tornadoes

龙卷风的风将各种各样的碎片抛向空中，其中一些被吸入龙卷风的漩涡。 气象雷达很容易观测到这些碎片，但它使近地面龙卷风的远程测量变得复杂。 该研究方案将侧重于将碎片运动与近地面龙卷风层中的空气运动分开，并调查龙卷风碎片和风场之间的关系。 还将继续研究龙卷风形成前发生的各个步骤的各个方面。 更好地了解龙卷风碎片对结构工程有潜在的影响，更好地了解龙卷风的发展对短期龙卷风预报很重要。 该奖项还将为下一代研究科学家提供培训，研究团队将分析现有的雷达数据，并使用RaXPol雷达进行新的观测，试图将龙卷风边界层中的碎片运动与空气运动分开。 研究人员计划测试这样一个假设，即龙卷风边界层中的空气运动在大多数情况下是真正收敛的，而不是像大部分散射体的运动那样发散，因为更大质量的散射体的运动。 这方面工作的目标是确定该小组是否能够利用LES生成的含有不同类型碎片的龙卷风生成真实的雷达回波，并将这些特征与RaXPol观测结果进行比较，并确定是否有可能利用多普勒频谱将碎片运动与空气运动分开。 该奖项将对过去十年收集的一系列龙卷风案例进行分析，特别关注雷达观测记录的超级单体内部的子结构。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Tornadic winds loft various types of debris into the air, some of which is ingested into the tornado’s vortex. The debris is readily viewed by weather radar, but it complicates the remote measurements of tornadic winds near the ground. This research program will focus on separating debris motion from air motion in the near-surface tornado layer and investigate the relationship between tornado debris and the wind field. Research will also continue on various aspects of the steps that occur prior to the formation of a tornado. Better understanding of tornado debris has a potential impact on structural engineering and improved understanding of tornado development is important for short-term tornado forecasts. This award will also provide training for the next generation of research scientists.The research team will analyze existing radar data and execute new observations using the RaXPol radar in an attempt to separate debris motion from air motion in the tornado boundary layer. The researchers plan to test the hypothesis that air motion in the tornado boundary layer is truly convergent most of the time, not divergent as is the motion of the bulk of the scatterers owing to the centrifuging of the more massive scatterers. The goals of this aspect of the work are to determine whether the team can generate realistic radar returns using an LES-generated tornado with different types of debris and compare the signatures to RaXPol observations, and to determine if it is possible to use Doppler spectra to separate debris motion from air motion. The tornadogenesis work will involve the analysis of a set of tornado cases collected over the last decade with specific focus on sub-structures within supercells that have been documented by radar observations.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.