05 Temporal evolution of snow on Arctic sea ice during MOSAiC

Macfarlane Amy1, Dadic Ruzica1/3, Wagner David1/4, Jaggi Matthias1, Krampe Daniela2, Arndt Stefanie2, Schneebeli Martin1

  1. WSL Institute for Snow and Avalanche Research SLF, Snow Physics, Davos, Switzerland
  2. Alfred-Wegener-Institute, Bremerhaven, Germany
  3. Victoria University, Wellington, New Zealand
  4. École polytechnique fédérale de Lausanne, CRYOS, Lausanne, Switzerland

The logistical challenges of directly measuring snow on sea ice in the remote high Arctic is one of the reasons there are so few time-series in this region. Between 10/2019 and 05/2020 Polarstern RV was used as a platform for scientists to conduct daily snow measurements on sea ice as part of the MOSAiC expedition above 82oN. Freezing in and drifting with the sea ice, gave the scientists onboard Polarstern the possibility to revisit the same locations on the ice and conduct unprecedented snow measurements at these sites. The underlying ice type plays a large influence on the snow’s temporal evolution. Re-frozen lead ice, first year ice, second year ice and ridge sites were all included in the revisited measurement locations.

The expedition was exposed to many extremes allowing for data collection in a variety of conditions. This included temperature differences between -39.5oC and 0oC, the transition between polar night and polar day and 25.1 m/s winds. Each of these conditions influence the snow’s optical and microstructural properties. For example, high temperature gradients inducing vapor transport, incoming solar radiation during polar day effecting the optical properties and wind compaction of the snow producing surface crusts.

A micro-computer tomograph was installed on the research vessel and allowed direct sampling of the snow’s microstructure. This was combined with analysis of the snow’s density and specific surface area with the SnowMicroPen and Near Infrared camera. Using this data set we begin to understand the influence of these extreme events on the snowpack and the temporal evolution of the snow in such a unique environment.