Measurement and characterization of infrasound from a tornado producing storm
Abstract
A hail-producing supercell on 11 May 2017 produced a small (EFU) tornado near Perkins, Oklahoma (35.97, -97.04) at 2013 UTC. Two infrasound microphones with a 59-m separation and a regional Doppler radar station were located 18.7 km and 70 km from the tornado, respectively. Elevated infrasound levels were observed starting 7 minutes before the verified tornado. Infrasound data below ~5 Hz was contaminated with wind noise, but in the 5-50 Hz band the infrasound was independent of wind speed with a bearing angle that was consistent with the movement of the storm core that produced the tornado. During the tornado, a 75 dB peak formed at ~8.3 Hz, which was 18 dB above pre-tornado levels. This fundamental frequency had overtones (18, 29, 36, and 44 Hz) that were linearly related to mode number. Analysis of a larger period of time associated with two infrasound bursts (the tornado occurred during the first event) shows that the spectral peaks from the tornado were present from 4 minutes before to 40 minutes after tornadogenesis. This suggests that the same geophysical process(es) was active during this entire window.
Cite
@article{arxiv.1809.00038,
title = {Measurement and characterization of infrasound from a tornado producing storm},
author = {Brian R. Elbing and Christopher E. Petrin and Matthew S. Van Den Broeke},
journal= {arXiv preprint arXiv:1809.00038},
year = {2019}
}