A Brief Critique of a Theory Used to Interpret the Infrasound of Tornadic Thunderstorms

Abstract

t has been proposed that the 0.5?10-Hz infrasound emitted by a severe storm is primarily generated by the axisymmetric oscillations of a tornado. This interpretation is challenged by a critical review of its theoretical foundation. A basic linear analysis shows that the principal axisymmetric oscillations of a subsonic, columnar vortex (axisymmetric Kelvin modes) cannot excite acoustic radiation. Numerical experiments further show that axisymmetric radiation is shaped primarily by the impulse that triggers the emission, not the properties of the vortex.