Nonlinear Infrasound Propagation Simulation by Hydrodynamic Models
Description:
Infrasound (low-frequency sound below 20 Hz) is a key technology used to monitor energetic events in the atmosphere. Energetic man-made or natural events (e.g., chemical/nuclear explosions, rockets, and earthquakes) create large pressure disturbances which propagate as infrasound in the atmosphere. It is well known that the stratification of Earth's atmosphere plays an important role in transmitting the infrasound signals. For examples, the strong wind and temperature changes in the stratosphere trap infrasonic energy efficiently and transmit them for long distances without significant loss of energy. Unlike infrasound propagation in the middle and lower atmospheres, the characteristics of infrasound in the upper atmosphere has been less studied. As the atmospheric density in the upper atmosphere is extremely low and thereby intrinsic attenuation is prominent, infrasound in the upper atmosphere is often assumed negligible. However, the increasing volume of high-quality data and the improved coverage of global infrasound network allow for identifying infrasound signals traveling in the upper atmospheres. In spite of increasing number of energetic sources and detection capability, the study of upper atmospheric infrasound has been limited by a tool to model signal propagation. The classical linear acoustic theory does not work for non-linear infrasound propagation in the low-density upper atmospheres, and non-linearized fluid physics is required. In this study, we investigate the applicability of widely used hydrodynamic models to the nonlinear infrasound. GEODYN is a hydrodynamic simulation code used for nonlinear deformation of material and blast wave propagation by explosions in the air. We apply GEODYN for infrasound propagation in the conditions of high-altitude atmosphere and evaluate its accuracy by the comparison with experiment data.
Session: Detecting, Locating, Characterizing and Monitoring Non-earthquake Seismoacoustic Sources [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Keehoon Kim
Student Presenter: No
Invited Presentation:
Authors
Keehoon Kim Presenting Author Corresponding Author kim84@llnl.gov Lawrence Livermore National Laboratory |
Oleg Vorobiev vorobiev1@llnl.gov Lawrence Livermore National Laboratory |
Efrem Vitali Vitali1@llnl.gov Lawrence Livermore National Laboratory |
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Nonlinear Infrasound Propagation Simulation by Hydrodynamic Models
Category
Detecting, Locating, Characterizing and Monitoring Non-earthquake Seismoacoustic Sources