Detection of differences in sea ice crystal structure using cross-borehole DC resistivity tomography

Abstract

Cross-borehole DC resistivity tomography measurements on first-year Antarctic sea ice show a decrease in the horizontal component of resistivity below 0.8 m in depth which is not related to changes in either temperature or brine volume fraction. Microstructural models derived from the resistivity data suggest that this change is related to an increased degree of horizontal connectivity in the brine microstructure of the ice. Comparison of the resistivity data with crystallographic measurements shows that this correlates with a change in ice structure from columnar ice to ice which contains an increasing fraction of platelet ice. It is thus demonstrated that not only can resistivity measurements track the temporal evolution of sea ice microstructure due to changes in temperature, but are also able to distinguish different ice types. This suggests that the dependence of sea ice properties on the distribution of brine inclusions can be studied in-situ through the use of resistivity measurements, providing a non-destructive technique for examining permeability–porosity relations in sea ice. ► We report cross-borehole DC resistivity measurements of Antarctic sea ice. ► The depth variation in resistivity does not correlate with changes in temperature. ► Structural models show horizontal connectivity of brine pore increases with depth. ► This is related to an increased proportion of incorporated platelet ice with depth.