Upper layer in the Arctic Eurasian basin (2007-2014) : stratification and eddies

The eurasian part of the Arctic Ocean has undergone important changes for the last 10 years. The sea ice cover is shrinking, the ice free ocean area in summer is larger and the period of melting is longer. This implies changes in the upper part of the ocean stratification.

We use several drifting buoys data to assess these modifications. Nine Ice Tethered Profilers (ITP) sampled the eurasian Arctic and between 2007 and 2014 (mainly during the summer) from the surface down to 800m. One IAOOS buoy equipped with a profiler mesuring temperature, salinity and dissolved oxygen down to 800m also drifted from the Barneo camp (near North Pole) to Fram Strait from April to September 2013.

In some profiles, a maximum of temperature is observed near the surface (around 25m depth) and at a deeper depth later in the year (around 40m depth). These local maxima of temperature are reminiscent of the NSTM (Near Surface Temperature Maximum) found in the Beaufort gyre and may be formed by similar processes. A decrease in the sea ice cover associated with an increase in the heat flux to the ocean may explain these near-surface maxima.

The eddy distribution/location is also examined using a density anomaly detection scheme. Cyclonic and anticyclonic eddies are found, with core-depths around 80m, 100m and 250-300m. The origins of the eddies are under investigation.