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The Silent Sounds of Tornadoes and Their Potential Fluid Mechanism
  • Brian Elbing,
  • Christopher Petrin
Brian Elbing
Oklahoma State University

Corresponding Author:elbing@okstate.edu

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Christopher Petrin
Oklahoma State University Main Campus
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Abstract

Sound at frequencies below the nominal bound of human hearing (~20 Hz) is called “infrasound.” Infrasound at frequencies between 0.5 and 10 Hz has been observed to be emitted by tornado-producing storms throughout the life of the tornado, including tornadogenesis. Due in part to the low atmospheric attenuation at these low frequencies, infrasound monitoring is a good candidate for long-range passive tornado monitoring, especially in hilly terrain where line-of-sight limits radar (e.g. Southeast United States). However, the fluid mechanism(s) responsible for the infrasound must be identified to enable researchers to interpret these currently unused signals. This is the objective of the current research, which has used multiple infrasound measurement modalities to identify correlations between received infrasound signals and storm processes. This includes a fixed infrasound array, a mobile infrasound array, and a single infrasound microphone carried by a storm chaser. An overview of select events will be presented, including measurements from an EFU tornado on 11 May 2017 that was within 20 km of the fixed array. These tornadic and non-tornadic observations will then be used to identify potential physical mechanisms.