On the use of electromagnetic induction sounding to determine winter and spring sea ice thickness in the Antarctic

The suitability of using a portable electromagnetic induction (EMI) soundin g device for determining sea ice thickness under winter and spring conditio ns in the Antarctic is evaluated. Ice thickness estimates from the instrume nt are compared with drilled measurements along a series of transects on Ea st Antarctic pack ice and fast ice. The data indicate that the instrument e stimates the undeformed sea ice thickness to within 10% of drilled thicknes s measurements; however, thickness estimates over deformed ice show much la rger deviations. Sea ice conductivity profiles along each transect were cal culated using ice core salinity data and ice-snow interface temperatures. T he analysis indicates that first-year Antarctic sea ice generally has a hig her conductivity (35-75 mS m(-1)) than reported for Arctic sea ice. However , this does not adversely affect the EMI sounding technique for determining sea ice thickness as this conductivity is still significantly less than fo r seawater, and the ice effectively remains transparent to the EM field. Th e EMI instrument used in this experiment was fitted with an ice thickness p rocessing module (PM) which provided accurate estimates of sea ice thicknes s once correctly calibrated. The results from these preliminary experiments over winter and spring Antarctic sea ice indicate that EMI sounding has gr eat potential to provide thickness data over the undeformed component of th e Antarctic pack ice at this time of year. (C) 1999 Elsevier Science B.V. A ll rights reserved.