Effects of atmospheric profiles on local infrasound propagation

Lammers, Andrew R

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https://hdl.handle.net/2142/101618 Copy

Description

Title

Effects of atmospheric profiles on local infrasound propagation

Author(s)

Lammers, Andrew R

Issue Date

2018-07-18

Director of Research (if dissertation) or Advisor (if thesis)

Rauber, Robert M.

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• infrasound propagation
• atmospheric profiles
• local infrasound

Abstract

A deep understanding of the impact of the natural environment on local (< 150 km) infrasound propagation is important, specifically for persistent infrastructure monitoring. Passively sensing the infrasound field provides useful information about the condition of infrastructure or any activity of interest in the infrasound passband. Meteorological profiles strongly influence the propagation of an infrasound signal via refraction; therefore, understanding the effects of different profiles is crucial for both determining the source of a signal and estimating how far away that signal may be readily detected. This paper focuses on simplified vertical temperature and wind profiles up to 20 km altitude and their effect on an infrasonic signal emanating from an arbitrary point source. A wide-angle, finite-element infrasound propagation model that correctly handles discontinuities in wavenumber is used for calculating transmission loss. A large number of simulations were performed to investigate the effect that meteorological profiles in different layers of the atmosphere have on surface transmission loss and to assess the impact of varying these profiles. Wind shear is found to be most impactful and it becomes clear that knowing the vertical wind profile is essential for determining the source of a received infrasonic signal. If wind shear is weak or non-existent, however, knowing the lapse rate in low altitudes to a high degree of accuracy is necessary. An in depth discussion and analysis of these results are presented as well as an overview of the infrasound propagation model and simplified meteorological profiles used in this study.

Graduation Semester

2018-08

Type of Resource

text

Permalink

http://hdl.handle.net/2142/101618

Copyright and License Information

Copyright 2018 Andrew Lammers

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