Observations of Under-Ice Heat and Momentum Fluxes from Drift Stations North of Svalbard

Unique measurements of under-ice turbulence were made from multiple drifting ice camps north of Svalbard in the winter and spring of 2015. Reynolds stresses and heat flux under the ice were measured by a mast holding two turbulence instrument clusters, measuring high frequency fluctuations of temperature and currents. Frequent ocean microstructure profiling down to 300m supplements the flux measurements. Spanning nearly half a year, the data set comprises observations of cold winter freezing conditions, winter storms and rapid melt events in spring. The camp drifted over the deep Nansen basin, across the shelf break onto the Yermak plateau and into the marginal ice zone, covering both quiescent mid-basin and more energetic mixing over the shelf break and plateau. Results obtained from these observations will be presented, providing new insight into processes of vertical mixing in the ice-ocean boundary layer in a region where underlying warm Atlantic-originating water threatens the shrinking ice cover.