Severe weather observations from a deployable four sensor infrasound array

Infrasound is sound at frequencies below 20 Hz. It has been observed to be emitted by tornado-producing storms up to two hours before tornadogenesis. Due to the low atmospheric attenuation of sound at these low frequencies, infrasound may be detected several hundreds of kilometers away under ideal atmospheric conditions. Therefore, passive infrasound monitoring has potential for the study and prediction of tornadoes and other severe weather if the received infrasound signals can be correlated with thermodynamic and flow field properties of the storms and/or tornadoes. Previous work accomplished at Oklahoma State University has focused on observations from a single stationary array located in Stillwater, OK. However, the large distance between this array and the nearest NEXRAD II radar stations makes low-level storm characterization challenging to accomplish in tandem with infrasound observation of severe weather. Therefore, a second array was designed to be deployable at various sites in Oklahoma within 50 km of the radar stations, in order to ensure low-altitude radar resolution. Containing four microphones, the new array was deployed during the summer of 2020 at several sites affiliated with the Oklahoma Mesonet. Details of the array's design and deployment will be presented, as well as preliminary data collected during non-tornadic thunderstorms in 2020. [This work was supported by NOAA Grant NA19OAR4590340 and NOAA Grant NA18OAR4590307.]