Central and Eastern European Infrasound Network: contribution to infrasound monitoring

Bondár, István; Šindelářová, Tereza; Ghica, Daniela; Mitterbauer, Ulrike; Liashchuk, Oleksandr; Baše, Jiří; Chum, Jaroslav; Czanik, Csenge; Ionescu, Constantin; Neagoe, Cristian; Pásztor, Marcell; Pichon, Alexis Le

doi:10.1093/gji/ggac066

Cited by 4 publications

(1 citation statement)

References 43 publications

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“…At present, operational infrasound networks are solely ground based (Alaska Volcano Observatory, 2016; Bondár et al., 2022; Burlacu et al., 2010; Christie & Campus, 2010; Marty, 2019). They can record sound waves from distant sources only when the stratospheric winds are favorable, or when the signal is sufficiently low frequency to permit transmission from the thermosphere.…”

Section: Introductionmentioning

confidence: 99%

The AtmoSOFAR Channel: First Direct Observations of an Elevated Acoustic Duct

Albert,

Bowman,

Silber

et al. 2023

Earth and Space Science

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The Sound Fixing and Ranging (SOFAR) channel in the ocean allows for low frequency sound to travel thousands of kilometers, making it particularly useful for detecting underwater nuclear explosions. Suggestions that an elevated SOFAR‐like channel should exist in the stratosphere date back over half a century and imply that sources within this region can be reliably sensed at vast distances. However, this theory has not been supported with evidence of direct observations from sound within this channel. Here we show that an infrasound sensor on a solar hot air balloon recorded the first infrasound detection of a ground truth airborne source while within this acoustic channel, which we refer to as the AtmoSOFAR channel. Our results support the existence of the AtmoSOFAR channel, demonstrate that acoustic signals can be recorded within it, and provide insight into the characteristics of recorded signals. Results also show a lack of detections on ground‐based stations, highlighting the advantages of using balloon‐borne infrasound sensors to detect impulsive sources at altitude.

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Section: Introductionmentioning

confidence: 99%

The AtmoSOFAR Channel: First Direct Observations of an Elevated Acoustic Duct

Albert,

Bowman,

Silber

et al. 2023

Earth and Space Science

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Atmospheric and ionospheric waves induced by the Hunga eruption on 15 January 2022; Doppler sounding and infrasound

Chum

Šindelářová

Knížová

et al. 2022

Geophysical Journal International

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Summary The massive explosive eruption of the Hunga volcano on 15 January 2022 generated atmospheric waves that were recorded around the globe and affected the ionosphere. The paper focuses on observations of atmospheric waves in the troposphere and ionosphere in Europe, however, a comparison with observations in East Asia, South Africa and South America is also provided. Unlike most recent studies of waves in the ionosphere based on the detection of changes in the total electron content, this study builds on detection of ionospheric motions at specific altitudes using continuous Doppler sounding. In addition, much attention is paid to long-period infrasound (periods longer than ∼50 s), which in Europe is observed simultaneously in the troposphere and ionosphere about an hour after the arrival of the first horizontally propagating pressure pulse (Lamb wave). It is shown that the long-period infrasound propagated approximately along the shorter great circle path, similar to the previously detected pressure pulse in the troposphere. It is suggested that the infrasound propagated in the ionosphere probably due to imperfect refraction in the lower thermosphere. The observation of infrasound in the ionosphere at such large distances from the source (over 16 000 km) is rare and differs from ionospheric infrasound detected at large distances from the epicenters of strong earthquakes, because in the latter case the infrasound is generated locally by seismic waves. An unusually large traveling ionospheric disturbance (TID) observed in Europe and associated with the pressure pulse from the Hunga eruption is also discussed. Doppler sounders in East Asia, South Africa and South America did not record such a significant TID. However, TIDs were observed in East Asia around times when Lamb waves passed the magnetically conjugate points. A probable observation of wave in the mesopause region in Europe approximately 25 min after the arrival of pressure pulse in the troposphere using a 23.4 kHz signal from a transmitter 557 km away and a coincident pulse in electric field data are also discussed.

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The Korean infrasound catalogue (1999–2022)

Park,

Arrowsmith,

Che

et al. 2024

Geophysical Journal International

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Summary The Korean infrasound catalog (KIC) covers 1999 to 2022 and characterizes a rich variety of source types as well as document the effects of the time-varying atmosphere on event detection and location across the Korean Peninsula. The KIC is produced using data from six South Korean infrasound arrays that are cooperatively operated by Southern Methodist University and Korea Institute of Geoscience and Mineral Resources. Signal detection relies on an Adaptive F-Detector (Arrowsmith et al., 2009) that estimates arrival time and backazimuth, which draws a distinction between detection and parameter estimation. Detections and associated parameters are input into a Bayesian Infrasonic Source Location procedure (Modrak et al., 2010). The resulting KIC contains 38,455 infrasound events and documents repeated events from several locations. The catalog includes many anthropogenic sources such as an industrial chemical explosion, explosions at limestone open-pit mines and quarries, North Korean underground nuclear explosions, and other atmospheric or underwater events of unknown origin. Most events in the KIC occur during working hours and days, suggesting a dominance of human-related signals. The expansion of infrasound arrays over the years in South Korea and the inclusion of data from the International Monitoring System infrasound stations in Russia and Japan increase the number of infrasound events and improve location accuracy because of the increase in azimuthal station coverage. A review of selected events and associated signals at multiple arrays provides a location quality assessment. We quantify infrasound events that have accompanying seismic arrivals (seismoacoustic events) to support the source type assessment. Ray tracing using the Ground-to-Space (G2S) atmospheric model generally predicts observed arrivals when strong stratospheric winds exist, although the predicted arrival times have significant discrepancies. In some cases, local atmospheric data better captures small-scale variations in the wind velocity of the shallow atmosphere and can improve arrival time predictions that are not well matched by the G2S model. The analysis of selected events also illustrates the importance of topographic effects on tropospheric infrasound propagation at local distances. The KIC is the first infrasound catalog compiled in this region, and it can serve as a valuable dataset in developing more robust infrasound source localization and characterization methods.

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Central and Eastern European Infrasound Network: contribution to infrasound monitoring

Cited by 4 publications

References 43 publications

The AtmoSOFAR Channel: First Direct Observations of an Elevated Acoustic Duct

The AtmoSOFAR Channel: First Direct Observations of an Elevated Acoustic Duct

Atmospheric and ionospheric waves induced by the Hunga eruption on 15 January 2022; Doppler sounding and infrasound

The Korean infrasound catalogue (1999–2022)

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