Mass Balance of Arctic Sea Ice North of Svalbard during N-ICE2015

Abstract:

The N-ICE2015 cruise, led by the Norwegian Polar Institute, was a drift experiment with the research vessel R/V Lancefrom January to June 2015, where the ship started the drift North of Svalbard at 83°14.45' N, 21°31.41' E. The drift was repeated as soon as the vessel drifted free. Altogether during the 6 month, 4 ice stations where installed and the complex ocean-sea ice-atmosphere system was studied with an interdisciplinary approach.

During the N-ICE2015 cruise, extensive ice thickness and snow depth measurements were performed during both, winter and summer conditions.

Total ice and snow thickness was measured with ground-based and airborne electromagnetic instruments like EM31, GEM, and EM-bird; snow depth was measured with a GPS snow depth probe. Additionally, ice mass balance and snow buoys were deployed.

Snow and ice thickness measurements were performed on repeated transects to quantify the ice growth or loss as well as the snow accumulation and melt rate. Additionally, we collected independent values on surveys to determine the general ice thickness distribution.

In terms of mass balance, average snow depths of 32 cm on first year ice, and 52 cm on multiyear ice were measured in January, the mean snow depth on all ice types even increased until end of March to 49 cm. The average total ice and snow thickness in winter conditions was 1.92 cm.

During winter, we found an unusual small growth rate on multiyear ice of about 15 cm in 2 months, due to above-average snow depths and some extraordanary storm events that came along with mild temperatures. In contrast thereto, we were also able to study new ice formation and thin ice on refrozen leads.

In summer conditions an enormous melt rate, mainly driven by a warm Atlantic water inflow in the marginal ice zone, was observed during two ice stations with melt rates of up to 20 cm per 24 hours.

The here presented dataset is a mandatory parameter for understanding the ocean-ice-atmosphere interactions, for calculating energy fluxes, and biogeochemical processes.