Identification of the infrasound signals emitted by explosive eruption of Mt. Shinmoedake by three-dimensional ray tracing

Saito, Hiroaki; Yamamoto, Tetsuo; Nakajima, Kensuke; Kuramoto, Kiyoshi; Yamamoto, Masa Yuki

doi:10.1121/10.0003366

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…These categories have different wave velocities, which vary as functions of the distance from the sound source to the sensor. The pressure variations, which continued for several hours in Japan, were not composed of a single wave but by multiple wave packets traveling along multiple paths at different speeds constrained by the dispersion relation 17 , 18 of waves under the effects of gravity and temperature inhomogeneities in the atmosphere. For example, low-frequency signals can propagate horizontally as gravity waves but cannot propagate vertically if the frequency is below the acoustic cut-off frequency (approximately 3.2 mHz at 15 C and at ground pressure); only high-frequency sound waves can propagate vertically.…”

Section: Resultsmentioning

confidence: 99%

“…One is refracted from the stratosphere; the other is refracted from the lower thermosphere. According to three-dimensional ray-tracing calculations for infrasound emitted by a volcanic eruption 18 , the velocity of some of the waves returning from the stratosphere is approximately 300 m/s, and that for waves from the lower thermosphere is approximately 238 m/s. We can explain the apparent propagation velocities based on the two-dimensional calculation of acoustic energy transmission loss in the azimuthal direction toward Japan based on a parabolic equation as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Observation and simulation of atmospheric gravity waves exciting subsequent tsunami along the coastline of Japan after Tonga explosion event

Nishikawa

Yamamoto

Nakajima

et al. 2022

Sci Rep

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Tsunamis are commonly generated by earthquakes beneath the ocean floor, volcanic eruptions, and landslides. The tsunami following the Tonga eruption of 2022 is believed to have been excited by atmospheric pressure fluctuations generated by the explosion of the volcano. The first, fast-traveling tsunami was excited by Lamb waves; however, it has not been clarified observationally or theoretically which type of atmospheric fluctuations excited more prominent tsunami which followd. In this study, we investigate atmospheric gravity waves that possibly excited the aforementioned subsequent tsunami based on observations and atmosphere-ocean coupling simulations. The atmospheric fluctuations are classified as Lamb waves, acoustic waves, or gravity waves. The arrival time of the gravity wave and the simulation shows that the gravity wave propagated at a phase speed of 215 m/s, coinciding with the tsunami velocity in the Pacific Ocean, and suggesting that the gravity wave resonantly excited the tsunami (Proudman resonance). These observations and theoretical calculations provide an essential basis for investigations of volcano-induced meteotsunamis, including the Tonga event.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Observation and simulation of atmospheric gravity waves exciting subsequent tsunami along the coastline of Japan after Tonga explosion event

Nishikawa

Yamamoto

Nakajima

et al. 2022

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…While this prevents ray proliferation, one ray is insufficient, and the implementation results in a very noisy image. [9][10].…”

Section: Path Tracingmentioning

confidence: 99%

Research and Analysis of Ray Tracing Methods

2023

ACE

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In computer graphics, the study of how to build realistic scenes on the computer has been the focus of research. The dominant approach to simulating the correct light source was to use rasterization, but rasterization does not correctly simulate multiple reflections. To make virtual scenes more realistic, ray tracing was proposed to provide better results. With the rapid development of computer hardware, the use of ray tracing for rendering animation or games is becoming more and more common, and many scenes can now be rendered with ray tracing instead of rasterization for better results. This paper introduces and analyses the various methods of ray tracing in chronological order, starting with the original forward ray tracing and backward ray tracing, followed by Whitted algorithms with recursion, and then a series of methods introducing rendering formulas. And then, a few rays tracing algorithms introducing the Metropolis sampling method is mentioned. One can conclude that this method is going to be used for future optimization and development. It is significant for the development of ray tracing.

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Modeling of 3D trajectory of Hayabusa2 re-entry based on acoustic observations

Nishikawa

Yamamoto

Sansom

et al. 2022

Publications of the Astronomical Society of Japan

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On 2020 December 5 at 17:28 UTC, Japan Aerospace Exploration Agency’s Hayabusa2 sample return capsule (SRC) re-entered Earth’s atmosphere. The capsule passed through the atmosphere at supersonic speeds, emitting sound and light. The inaudible sound was recorded by infrasound sensors installed by Kochi University of Technology and Curtin University. Based on analysis of the recorded infrasound, the trajectory of the SRC in two cases, one with constant-velocity linear motion and the other with silent flight, could be estimated with an accuracy of ${0{_{.}^{\circ}}5}$ in elevation and 1° in direction. A comparison with optical observations suggests a state of flight in which no light is emitted but sound is emitted. In this paper, we describe the method and results of the trajectory estimation.

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Identification of the infrasound signals emitted by explosive eruption of Mt. Shinmoedake by three-dimensional ray tracing

Cited by 5 publications

References 14 publications

Observation and simulation of atmospheric gravity waves exciting subsequent tsunami along the coastline of Japan after Tonga explosion event

Observation and simulation of atmospheric gravity waves exciting subsequent tsunami along the coastline of Japan after Tonga explosion event

Research and Analysis of Ray Tracing Methods

Modeling of 3D trajectory of Hayabusa2 re-entry based on acoustic observations

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