| Fluid flow through sea ice mediates a broad range of geophysical and biological processes,
such as biomass build-up sustained by nutrient fluxes, the evolution of melt ponds and
summer ice albedo, CO2 exchanges, snow-ice formation, and the evolution of the salt budget.
However, for brine volume fractions below about 5%, columnar sea ice is effectively
impermeable to fluid flow, which controls these processes. In two different experiments
conducted in the Arctic and Antarctic, we have found that this critical transition in fluid flow
exhibits a strong, characteristic electrical signature. Sea ice conductivity data are accurately
explained by percolation theory, with the same universal critical exponent of 2 which
captures the behavior of the fluid permeability. Our findings lay the foundation for
electromagnetic monitoring of transport phenomena in sea ice, which can help track key
transitions in the state of polar sea ice and improve projections of its fate and impact on
ecosystems. We electrically classify various layers in sea ice in terms of their fluid flow
properties, thus connecting specific electrical signatures to important processes
such as melt pond drainage, CO2 pumping, and nutrient fluxes. We will also briefly
discuss related work on electromagnetic inversion for connectedness data on the
brine inclusions in sea ice, the influence of EPS on brine inclusion statistics and
transport properties, and evidence for higher percolation thresholds in granular ice. |