In-situ measurements of the low frequency dielectric permittivity of first-year Antarctic sea ice

Measurement of the low frequency dielectric permittivity of sea ice is an important step in developing microstructural models that will permit the calculation of other physical properties of sea ice. We report the adaptation of the technique of cross-borehole resistivity tomography to obtain in-situ measurements of the horizontal component of the permittivity of first year Antarctic sea ice. Results show features of the permittivity previously identified from measurements on laboratory grown artificial sea ice. Modeling of the measured permittivity curves allows estimates of physical parameters related to the conduction mechanisms in the ice to be made. Both ε∞, the high frequency relative permittivity, and χ, the susceptibility of the Debye relaxation, appear to depend upon brine volume fraction, while the time constant of relaxation is consistent with values determined from previous studies. Empirical parameters representing the effect of space charge polarization show complicated relationships with temperature, salinity and brine volume fraction. There are also indications that differences in some of these parameters occur between columnar ice, observed to exist to a depth of about 1.1 m, and incorporated platelet ice below this depth.