Date of Award

12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ocean Engineering and Marine Sciences

First Advisor

Stephen Wood

Second Advisor

Ronnal Reichard

Third Advisor

Chelakara S. Subramanian

Fourth Advisor

Geoffrey Swain

Abstract

Ocean dynamics are an important contributing factor to measurable environmental magnetic noise. Seawater is conductive and as an internal wave oscillates across Earth’s magnetic field, a small yet detectable induced magnetic field develops. A significant source of underwater magnetic noise off the southeast coast of Florida comes from internal waves. Characterizing the magnetic signals present required a combination of computational modeling effort and field experiments. For this research, undersea sensors were monitored as a continuous field experiment and a computational fluid dynamic (CFD) magneto-hydrodynamic (MHD) model was customized to simulate internal wave-induced magnetic fields at the site. I developed the methods to detect, analyze and characterize internal waves as a part of this project. Several large internal wave events were found and examined using methods such as Empirical Orthogonal Function analysis and signal-to-noise ratio. A strong correlation between the internal wave velocity field and magnetic signal detected on the seafloor was demonstrated. The CFD-MHD model successfully re-created the magnetic field from large internal wave motion and compared well to the sensor data. Use of this model with simulated data was also demonstrated. The results of this project contribute to the understanding of magnetic noise at the site caused by the movement of internal waves. The model has shown to be useful in quantifying magnetic signals created by the internal wave velocity field and as a potential tool to predict magnetics at other sites.

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