Studies of Severe Convective Storms and Tornadoes

这项研究项目的目标是更好地了解强对流风暴和龙卷风的动力学。这一目标将通过分析观测数据集和理想化的数值模拟实验来实现。在龙卷风中收集的移动多普勒雷达数据集将被详细分析，并将进行小型、聚焦的现场实验来收集和分析额外的数据，以获得更好的龙卷风及其环境的统计特征。这项工作的主要目的将是估计龙卷风中近地面的风速，确定龙卷风中的三维风场，确定龙卷风形成和消散的原因，并找出为什么一些超级单体风暴产生龙卷风，而另一些超级单体风暴不产生龙卷风。为了了解在机载多普勒雷达分析非龙卷风超级单体冰雹时观察到的后喷流上升和反向旋转涡旋对联的动力学，将进行数值模拟实验。假设涡联是由于风暴下沉气流对水平涡度的倾斜而产生的。这项研究的重要性在于，尾流急流和涡旋对联可能是超单体风暴的一个亚类。这项研究的成功完成将导致更好的龙卷风和龙卷风成因的概念模型，并最终导致更准确的预测。

The goal of this research project is to understand better the dynamics of severe convective storms and tornadoes. This goal will be met through the analysis of observational data sets and from idealized numerical simulation experiments.Mobile Doppler radar data sets collected in tornadoes will be analyzed in detail and a small, focussed field experiment will be conducted to collect and analyze additional data in order to obtain a better statistical characterization of tornadoes and their environment. The main thrust of this effort will be to estimate wind speeds near the ground in tornadoes, determine the three-dimensional wind field in tornadoes, determine why tornadoes form and dissipate and find out why some supercell storms produce tornadoes, while others do not.Numerical simulation experiments will be conducted in order to understand the dynamics of an elevated rear-inflow jet and a counterrotating vortex couplet observed in an airborne Doppler radar analyses of a nontornadic supercell hailstorm. It is hypothesized that the vortex couplet was created through the tilting of horizontal vorticity by the downdraft in the storm. The importance of this study is that the rear-inflow jet and vortex couplet may be characteristic of a subclass of supercell storms.Successful completion of this research will lead to better conceptual models of tornadoes and tornado genesis and eventually lead to more accurate predictions.