Investigation of electromagnetic induction retrievals of sea ice thickness using models and measurements
Date
2016
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Publisher
University of Delaware
Abstract
Using sea ice as a test material, this dissertation explores how electromagnetic responses interact with low-induction-number composite materials as a function of instrument footprint size and shape. This research combines several interdisciplinary topics including electrical engineering, materials science in composites, signal processing, and the geophysics of sea ice itself. Specifically, this work explores the development of new best practices that address consistency issues with electromagnetic induction instruments used on sea ice that employ electrical conductivity as a material property measurement. It does so by using two methods: modeling and measurements. For modeling, a three-dimensional, full-physics, heterogeneous model is used to investigate the electromagnetic field response of several sea ice cases. These cases include changing the material makeup of the sea ice, as well as using different transmitter locations and orientations, with the focus being how instrument footprint varies in each simulated case. For measurements, a co-calibration routine, among two physically different EM induction instruments in terms of instrument footprint, is developed and analyzed. Since these types of instruments are commonly used to measure conductivity in sea ice environments, historical calibration routines are only valid for one instrument at a time. The developed method presented herein provides a statistical solution for the material conductivities of both sea ice and seawater, as well as a solution for the actual ice thickness. These solutions are all based on field measurements made on sea ice during a data collection event held in Barrow, Alaska, in March 2013.