The stratospheric arrival pair in infrasound propagation

Waxler, Roger; Evers, Läslo; Assink, Jelle; Blom, Philip

doi:10.1121/1.4916718

Cited by 37 publications

(13 citation statements)

References 24 publications

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“…Balloons are not limited to land but can travel over the ocean as well. Regions of the atmosphere centered around temperature minima can serve as infrasound wave guides (e.g., Waxler, Evers, et al, 2015) that they may be able to capture.…”

Section: Introductionmentioning

confidence: 99%

Explosion‐Generated Infrasound Recorded on Ground and Airborne Microbarometers at Regional Distances

Young

Bowman

Lees

et al. 2018

Seismological Research Letters

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Recent work in deploying infrasound (low-frequency sound) sensors on aerostats and free-flying balloons has shown them to be viable alternatives to ground stations. However, no study to date has compared the performance of surface and freefloating infrasound microbarometers with respect to acoustic events at regional (100s of kilometers) range. The prospect of enhanced detection of aerial explosions at similar ranges, such as those from bolides, has not been investigated either. We examined infrasound signals from three 1-ton trinitrotoluene (TNT) equivalent chemical explosions using microbarometers on two separate balloons at 280-to 400-km ranges and ground stations at 6.3-to 350-km ranges. Signal celerities were consistent with acoustic waves traveling in the stratospheric duct. However, significant differences were noted between the observed arrival patterns and those predicted by an acoustic propagation model. Very low-background noise levels on the balloons were consistent with previous studies that suggest wind interference is minimal on freely drifting sensors. Simulated propagation patterns and observed noise levels also confirm that balloon-borne microbarometers should be very effective at detecting explosions in the middle and upper atmosphere as well as those on the surface.

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Section: Introductionmentioning

confidence: 99%

Explosion‐Generated Infrasound Recorded on Ground and Airborne Microbarometers at Regional Distances

Young

Bowman

Lees

et al. 2018

Seismological Research Letters

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“…Numerous natural and anthropogenic sources emit infrasound, sound at frequencies below human hearing (< 20 Hz). Known sources include severe storms (Jones & Georges, 1976;Talmadge & Waxler, 2016), earthquakes (Young & Greene, 1982;Le Pichon et al, 2005;Mutschlecner & Whitaker, 2005), explosions/rocket launches (Waxler et al, 2015;Blom et al, 2016), ocean waves (Waxler & Gilbert, 2006), and volcanoes (Johnson & Ripepe, 2011). Due to weak atmospheric absorption at low frequency and an "acoustic ceiling" within the atmosphere (Bedard & Georges, 2000), infrasound can be detected over significantly larger distances than audible sound.…”

Section: Introductionmentioning

confidence: 99%

Measurement and characterization of infrasound from a tornado producing storm

Elbing

Petrin

Broeke

2019

The Journal of the Acoustical Society of America

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A hail-producing supercell on 11 May 2017 produced a small (EFU) tornado near Perkins, Oklahoma (35.97,.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.

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“…Unlike the elastic medium, which remains constant in time, atmospheric conditions change rapidly. The detectability of infrasound at large propagation distances (>200 km) highly depends on the state of the stratosphere (Assink, Waxler, et al, ; Waxler et al, ).…”

Section: Introductionmentioning

confidence: 99%

Seismoacoustic Coupled Signals From Earthquakes in Central Italy: Epicentral and Secondary Sources of Infrasound

Shani‐Kadmiel

Assink

Smets

et al. 2018

Geophysical Research Letters

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In this study we analyze infrasound signals from three earthquakes in central Italy. The Mw 6.0 Amatrice, Mw 5.9 Visso, and Mw 6.5 Norcia earthquakes generated significant epicentral ground motions that couple to the atmosphere and produce infrasonic waves. Epicentral seismic and infrasonic signals are detected at I26DE; however, a third type of signal, which arrives after the seismic wave train and before the epicentral infrasound signal, is also detected. This peculiar signal propagates across the array at acoustic wave speeds, but the celerity associated with it is 3 times the speed of sound. Atmosphere‐independent backprojections and full 3‐D ray tracing using atmospheric conditions of the European Centre for Medium‐Range Weather Forecasts are used to demonstrate that this apparently fast‐arriving infrasound signal originates from ground motions more than 400 km away from the epicenter. The location of the secondary infrasound patch coincides with the closest bounce point to I26DE as depicted by ray tracing backprojections.

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The stratospheric arrival pair in infrasound propagation

Cited by 37 publications

References 24 publications

Explosion‐Generated Infrasound Recorded on Ground and Airborne Microbarometers at Regional Distances

Explosion‐Generated Infrasound Recorded on Ground and Airborne Microbarometers at Regional Distances

Measurement and characterization of infrasound from a tornado producing storm

Seismoacoustic Coupled Signals From Earthquakes in Central Italy: Epicentral and Secondary Sources of Infrasound

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