Applications of Ray-Tracing to Observations of Mountain-Associated Infrasonic Waves

Rockway, J. W.; Hower, G. L.; Craine, L. B.; Thomas, J. E.

doi:10.1111/j.1365-246x.1974.tb03637.x

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…The phenomena sometimes display diurnal variations; at other time, the amplitudes diminish or increase without the evidence of classical periodicities. There are also infrasound sources that appear to originate from local mountains (Rockaway et al 1974). …”

Section: Persistent Unknown Sources Of Infrasoundmentioning

confidence: 99%

Infrasound, human health, and adaptation: an integrative overview of recondite hazards in a complex environment

Persinger

2013

Nat Hazards

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Infrasound displays a special capacity to affect human health and adaptation because its frequencies and amplitudes converge with those generated by the human body. Muscle sounds and whole-body vibrations are predominately within the 5-to 40-Hz range. The typical amplitudes of the oscillations are within 1-50 lm, which is equivalent to the pressures of about 1 Pa and energies in the order of 10 -11 W m -2 . Infrasound sources from the natural environment originate from winds, microbaroms, geomagnetic activity, and microseisms and can propagate for millions of meters. Cultural sources originate from air moving through duct systems within buildings, large machinery, and more recently, wind turbines. There are also unknown sources of infrasound. It is important to differentiate the effects of infrasound from the awareness or experience of its presence. Moderate strength correlations occur between the incidences of infrasound and reports of nausea, malaise, fatigue, aversion to the area, non-specific pain, and sleep disturbances when pressure levels exceed about 50 db for protracted periods. Experimental studies have verified these effects. Their validity is supported by convergent quantitative biophysical solutions. Because cells interact through the exchange of minute quanta of energy that corresponds with remarkably low levels of sound pressure produced by natural phenomena and wind turbines upon the body and its cavities, traditional standards for safety and quality of living might not be optimal.

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Section: Persistent Unknown Sources Of Infrasoundmentioning

confidence: 99%

Infrasound, human health, and adaptation: an integrative overview of recondite hazards in a complex environment

Persinger

2013

Nat Hazards

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“…The exact source mechanism of MAWs has not fully been solved yet. In addition to topography, the meteorological conditions were considered relevant not only for the propagation of MAWs (Rockway et al 1974 ), but also and particularly for the excitation. Larson et al ( 1971 ) found a correlation between the MAW occurrence as well as amplitude and tropospheric wind conditions, particularly of mountain chain crosswinds and proposed complex feedback mechanisms of the acoustic energy reinforcing the sound-producing flow, such as ground and terrain reflection or turbulent flows when surrounding obstacles such as mountain peaks.…”

Section: Infrasonic Sourcesmentioning

confidence: 99%

Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

et al. 2022

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The record of seismic, hydroacoustic, and infrasonic waves is essential to detect, identify, and localize sources of both natural and anthropogenic origin. To guarantee traceability and inter-station comparability, as well as an estimation of the measurement uncertainties leading to a better monitoring of natural disasters and environmental aspects, suitable measurement standards and reliable calibration procedures of sensors, especially in the low-frequency range down to 0.01 Hz, are required. Most of all with regard to the design goal of the Comprehensive Nuclear-Test-Ban Treaty Organisation’s International Monitoring System, which requires the stations to be operational nearly 100% of the time, the on-site calibration during operation is of special importance. The purpose of this paper is to identify suitable excitation sources and elaborate necessary requirements for on-site calibrations. We give an extensive literature review of a large variety of anthropogenic and natural sources of seismic, hydroacoustic, and infrasonic waves, describe their most prominent features regarding signal and spectral characteristics, explicitly highlight some source examples, and evaluate the reviewed sources with respect to requirements for on-site calibrations such as frequency bandwidth, signal properties as well as the applicability in terms of cost–benefit. According to our assessment, earthquakes stand out across all three waveform technologies as a good natural excitation signal meeting the majority of the requirements. Furthermore, microseisms and microbaroms allow a calibration at very low frequencies. We also find that in each waveform technique man-made controlled sources such as drop weights or air guns are in good agreement with the required properties, although limitations may arise regarding the practicability. Using these sources, procedures will be established allowing calibration without record interrupting, thereby improving data quality and the identification of treaty-related events.

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“…The latter were supposed to support the theory of air turbulence being a source of MAW excitation, which was also proposed by Thomas et al (1974) before. However, Rockway et al (1974) remarked that the effect of atmospheric conditions on the propagation and detection of MAWs might have been underestimated in previous theories. Their ray-tracing model showed that winds affecting propagation conditions were a vital issue for the seasonality of MAW detections.…”

Section: Introductionmentioning

confidence: 99%

“…According to Campbell and Young (1963), auroral activity was known to produce sound in this frequency range (see also Wilson et al, 2010), but Cook (1969) found, as a result of triangulation, that his observations traced back to mountainous regions (Larson et al, 1971). Therefore, these acoustic waves have been referred to as mountain-associated sound (Chimonas, 1977) or, more commonly, as MAWs (Larson et al, 1971;Rockway et al, 1974;Thomas et al, 1974;Greene and Howard, 1975;Bedard, 1978). Larson et al (1971) used data of three sites in the USA -in Alaska, Colorado, and Idaho -and measured amplitudes of 0.05 Pa to 0.7 Pa.…”

Section: Introductionmentioning

confidence: 99%

Mountain-Associated Waves and their relation to Orographic Gravity Waves

Hupe¹,

Ceranna²,

Pilger³

et al. 2021

metz

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Infrasound covers frequencies of around 10 −3 Hz to approximately 20 Hz and can propagate in atmospheric waveguides over long distances as a result of low absorption, depending on the state of the atmosphere. Therefore, infrasound is utilized to detect atmospheric explosions. Following the opening of the Comprehensive Nuclear-Test-Ban Treaty for signature in 1996, the International Monitoring System (IMS) was designed to detect explosions with a minimum yield of one kiloton of TNT equivalent worldwide. Currently 51 out of 60 IMS infrasound stations are recording pressure fluctuations of the order of 10 −3 Pa to 10 Pa. In this study, this unique network is used to characterize infrasound signals of so-called Mountain-Associated Waves (MAWs) on a global scale. MAW frequencies range from 0.01 Hz to 0.1 Hz. Previous observations were constrained to regional networks in America and date back to the 1960s and 1970s. Since then, studies on MAWs have been rare, and the exact source generation mechanism has been poorly investigated. Here, up to 16 years of IMS infrasound data enable the determination of global and seasonal MAW source regions. A cross-bearing method is applied which combines the dominant back-azimuth directions of different stations. For better understanding the MAW generation conditions, the MAW occurrence is compared to tropospheric winds at the determined hotspots. Furthermore, ray-tracing simulations reflect middle atmosphere dynamics for describing monthly propagation characteristics. Both the geographic source regions and the meteorological conditions agree with those of orographic gravity waves (OGWs). A comparison with GW hotspots, derived from satellite data, suggests that MAW source regions match those of OGWs. Discrepancies in the respective source regions result from a stratospheric wind minimum that prevents an upward propagation of OGWs at some hotspots of MAWs. The process of breaking GWs is discussed in terms of the MAW generation.

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Applications of Ray-Tracing to Observations of Mountain-Associated Infrasonic Waves

Cited by 5 publications

References 2 publications

Infrasound, human health, and adaptation: an integrative overview of recondite hazards in a complex environment

Infrasound, human health, and adaptation: an integrative overview of recondite hazards in a complex environment

Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

Mountain-Associated Waves and their relation to Orographic Gravity Waves

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