Full-physics 3D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

• Published in: Annals of glaciology Vol. 56; no. 69
• Main Authors: Samluk, Jesse P., Geiger, Cathleen A., Weiss, Chester J., Kolodzey, James
• Format: Journal Article
• Language: English
• Published: United States International Glaciological Society 01.10.2015
• Subjects: GEOSCIENCES
• DOI: 10.3189/2015AoG69A737
• ISSN: 0260-3055

In this article we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell's equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water as a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as 'null lines'. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.