Journal ArticleDOI
The Temporal Morphology of Infrasound Propagation
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TLDR
A new code is presented that integrates the local (range-independent) τp ray equations to provide travel time, range, turning point, and azimuth deviation for any location on the globe given a G2S vector spherical harmonic coefficient set.Abstract:
Expert knowledge suggests that the performance of automated infrasound event association and source location algorithms could be greatly improved by the ability to continually update station travel-time curves to properly account for the hourly, daily, and seasonal changes of the atmospheric state. With the goal of reducing false alarm rates and improving network detection capability we endeavor to develop, validate, and integrate this capability into infrasound processing operations at the International Data Centre of the Comprehensive Nuclear Test-Ban Treaty Organization. Numerous studies have demonstrated that incorporation of hybrid ground-to-space (G2S) enviromental specifications in numerical calculations of infrasound signal travel time and azimuth deviation yields significantly improved results over that of climatological atmospheric specifications, specifically for tropospheric and stratospheric modes. A robust infrastructure currently exists to generate hybrid G2S vector spherical harmonic coefficients, based on existing operational and emperical models on a real-time basis (every 3- to 6-hours) (Drobet al.,2003). Thus the next requirement in this endeavor is to refine numerical procedures to calculate infrasound propagation characteristics for robust automatic infrasound arrival identification and network detection, location, and characterization algorithms. We present results from a new code that integrates the local (range-independent) τp ray equations to provide travel time, range, turning point, and azimuth deviation for any location on the globe given a G2S vector spherical harmonic coefficient set. The code employs an accurate numerical technique capable of handling square-root singularities. We investigate the seasonal variability of propagation characteristics over a five-year time series for two different stations within the International Monitoring System with the aim of understanding the capabilities of current working knowledge of the atmosphere and infrasound propagation models. The statistical behaviors or occurrence frequency of various propagation configurations are discussed. Representative examples of some of these propagation configuration states are also shown.read more
Citations
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Book ChapterDOI
Monitoring the Earth’s Atmosphere with the Global IMS Infrasound Network
TL;DR: The comprehensive nuclear test-ban treaty organization (CTBTO) is tasked with monitoring compliance with the comprehensive nuclear-test-ban Treaty (CTBT), which bans nuclear weapon explosions underground, in the oceans, and in the atmosphere as mentioned in this paper.
Book ChapterDOI
Worldwide Observations of Infrasonic Waves
P. Campus,D. R. Christie +1 more
TL;DR: The International Monitoring System (IMS) is designed to ensure compliance with the comprehensive nuclear-test-ban treaty (CTBT) The IMS consists of a 60-station network of infrasound monitoring stations distributed uniformly over the face of the globe as discussed by the authors.
Journal ArticleDOI
A global study of volcanic infrasound characteristics and the potential for long-range monitoring
TL;DR: In this article, the authors assess the ability of the International Monitoring System (IMS) infrasound network to monitor remote volcanoes and investigate whether volcanic infrasounds exhibits consistent trends across a range of eruption styles and intensities.
Journal ArticleDOI
Infrasound radiated by the Gerdec and Chelopechene explosions: propagation along unexpected paths
TL;DR: In this article, the authors used a time-domain Parabolic Equation (PE) model to simulate the pulsed nature of infrasonic signals to predict peak signal amplitudes to within an order of magnitude of the observed values.
Book ChapterDOI
Volcano Infrasound and the International Monitoring System
TL;DR: In this article, the authors review recent advances in the field of volcano acoustics with an emphasis on scientific and potential civil application gains from the International Monitoring System (IMS) infrasound network.
References
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Journal ArticleDOI
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Book
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TL;DR: In this article, the authors describe a number of different types of inverse problems, such as the least squares problem, the purely underdetermined problem, and the Mixed*b1Determined problem.
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