A Numerical Modeling Investigation of Infrasound Generated by Tornadic Storms

观测表明，龙卷风和严重的风暴会产生频率低于人类听力范围的声波（称为次声）。龙卷风次声的频率范围约为0.5-10赫兹，高于其他强风暴发出的次声，也高于传统次声研究所涵盖的范围。如果可以通过这种独特的频率特征来检测龙卷风，那么就有可能开发出具有重大社会效益的新的预警系统。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。初步模拟提供了一套假设的基础上，关于次声是如何产生的，包括径向振动的涡核，这似乎是最有希望的。覆盖这一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了解龙卷风产生次声的机制。这一理解也将为考虑是否可以将基于次声的探测系统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，因此通过这种方法进行检测可能会对公共安全做出宝贵贡献。

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.