How porous, organism-rich layers form in Antarctic sea ice

Noting that during summer the temperature of air, sea ice, and ocean are in near equilibrium around the freezing point of seawater, Ackley et al. investigate the cause for a specific feature of Antarctic summer sea ice: partially melted honeycomb-like ice matrices filled with seawater that form below a surface layer of snow and ice. Called "gap layers," these features contain especially high algal and microbial content.
Using a model of gap layer formation that takes into account the summer reversal in near-surface temperature gradients in the Antarctic sea ice and the thermal conductivity found in the upper ice column, the authors calculate that the gap layer forms at a rate of up to three fourths of a centimeter per day.

Their analysis reveals why gap layers are common within Antarctic summer sea ice and that gap layers should be considered when analyzing melting scenarios, perhaps at both poles.-American Geophysical Union