A Numerical Modeling Investigation of Infrasound Generated by Tornadic Storms

观察表明，龙卷风和强风暴产生的声波频率低于人类听觉范围（称为次声）。龙卷风次声的频率范围约为0.5-10赫兹，高于强风暴发出的其他次声，也高于传统次声研究所涵盖的范围。如果龙卷风可以通过这种独特的频率特征被探测到，就有可能开发出新的预警系统，这可能会带来巨大的社会效益。在这个项目中，研究人员将使用一个数值模型来模拟龙卷风风暴产生的次声。初步的模拟为一系列关于次声如何产生的假设提供了基础，其中包括涡旋核心的径向振动，这似乎是最有希望的。覆盖该频率范围的现有观测结果为模拟提供了基准，也将作为本项目的案例研究进行审查。预期的结果是更好地理解龙卷风产生次声的机制。这种理解也将为考虑基于次声的探测系统是否可以作为龙卷风的预警系统奠定更好的基础。由于次声传播距离很长，用这种方法进行探测可能对公共安全作出有价值的贡献。

Observations have shown that tornadoes and severe storms produce acoustic waves at a frequency below the range of human hearing (called infrasound). Tornado infrasound has a frequency range of about 0.5-10 Hz, which is higher than other infrasound emanating from severe storms and above the range covered by conventional infrasound studies. If tornadoes can be detected by this distinct frequency signature, it may be possible to develop new advance-warning systems that could be of substantial societal benefit. In this project, the investigators will use a numerical model to simulate the generation of infrasound from tornadic storms. Preliminary simulations have provided the basis for a set of hypotheses regarding how the infrasound is generated, including radial vibration of the vortex core which appears to be the most promising. Existing observations covering this frequency range provide benchmarks for the simulations and will also be examined as case studies in this project. The expected outcome is a better understanding of the mechanisms by which tornadoes generate infrasound. This understanding will also establish a better basis for considering if a detection system based on infrasound could serve as an advance-warning system for tornadoes. Because infrasound propagates over long distances, detection by this method might provide a valuable contribution to public safety.