Sea Ice Thickness Measurement in Polar Environments: An Electromagnetic Detection Approach Using a Dual-Receiver Coil System

Electromagnetic induction (EM) is one of the established techniques for in-situ sea ice thickness measurement. It is typically implemented using shipborne or airborne transmitter-receiver coil systems (e.g., EM 31, AWI, DIGHEM) operating at single or multiple frequencies. While this method can acquire reliable sea ice thickness data, limitations exist in case of thin ice and regions with severely variable ice thickness . The fixed coil spacing (e.g., 3.66 m for EM 31) constrains detection sensitivity for thin ice, particularly in shipborne or airborne measurements where altitude variations can significantly affect inversion accuracy . To enhance thin-ice detection capability and inversion stability, this study proposes a novel electromagnetic induction method utilizing dual receiver coils.

This method retains a single transmitter coil and incorporates two receiver coils with a spacing of 0.5 m. By increasing the amount of measured data, the response characteristics for thin-layer targets are optimized. Based on typical polar sea ice conductivity parameters (seawater ~2.6 S/m, sea ice ~0.06 S/m), electromagnetic numerical simulations were conducted for sea ice with thicknesses ranging from 1 to 5 m. These simulations analyzed the response relationship between the secondary field signal and ice thickness under the dual-receiver coil configuration. The results indicate that, compared to traditional single-receiver coil systems, data from the dual-receiver coils exhibit greater sensitivity to variations in thin ice thickness and help reduce inversion uncertainty caused by fluctuations in measurement altitude.

Building on the simulation data, this study further developed an inversion algorithm for dual-receiver coil data. This algorithm integrates dual-channel data continuously acquired along the same direction to achieve accurate and stable inversion of sea ice thickness. Preliminary verification shows that the inversion uncertainty of this method for thin ice in the 1~3 m range is significantly lower than that of conventional methods. This approach provides a new technical pathway for developing next-generation portable, low-platform (ground-based, shipborne, or UAV-borne) sea ice thickness detection equipment. It contributes to enhancing capabilities in climate research and safety assurance for polar navigation.