Robbie Mallett , Vishnu Nandan, Julienne Stroeve, Rosemary Willatt, Monojit Saha, John Yackel, Gaëlle Veysière, Jeremy Wilkinson

The presence of salt in the snow overlying seasonal sea ice has profound thermodynamic and electromagnetic effects. However, the way that it arrives and is distributed within the marine snowpack remains poorly understood and modelled. We describe two experiments tracing upward brine movement in snow: one laboratory experiment at Rothera research station, West Antarctica, and a field experiment in Hudson Bay, Canada. The laboratory experiments involved the addition of dyed brine to the base of terrestrial snow samples, with subsequent wicking being characterised. After initial and total absorption at the base, the dyed brine migrated further up over nine days, ultimately reaching heights between 2.5 & 6 cm. Our field experiment involved dye being added directly (without brine) to bare sea ice and lake ice surfaces, with snow then accumulating on top over several days. On the sea ice, the dye migrated upwards into the snow by up to 5 cm as the snow's basal layer became more salty, whereas no dye migration occurred in our control experiment over lake ice. Upward dye migration and basal salinification over the sea ice occurred in relatively dry snowpacks where brine inclusions took up between 0.5 & 5.8% of the snow's pore volume.