First Advisor

Lisa M. Zurk

Date of Award

6-14-2013

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Geology and University Honors

Department

Geology

Subjects

Acoustic emission -- Simulation methods, Sea ice -- Polar regions, Underwater acoustics

DOI

10.15760/honors.18

Abstract

As the seasons change, sea ice in the polar regions undergoes a freeze-thaw cycle producing anisotropic sea ice in terms of physical properties and structures. Deformation of these variable structures from the freeze-thaw cycle and flux of energy within the polar regions causes the ice to fracture radiating noise into the water. Simulating the noise from sea ice is difficult due to the variability in the physical properties of sea ice, dynamic environment of the polar regions, complex physics governing sound propagation and numerous methods by which the emission of noise can be generated from sea ice. The radiated ambient noise generated from deforming sea ice can influence the habits of oceanic life, targeting abilities of vessels equipped with sonar, and add to the background acoustic noise in the polar regions. This work addresses the noise generated by opening (Mode I) fractures in sea ice. OASN was used to simulate acoustic waves propagating through the complex arctic environment. For this problem, a significant understanding of mathematics was required to overcome a mathematical aberration, within the computational tool, which was reduced and compared against simulations computed by an alternate propagation tool, RAM. Simulations of Model I fractures were compared against observed data. The methods developed for the simulation of Mode I fractures was proven successful.

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Persistent Identifier

http://archives.pdx.edu/ds/psu/10234

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