In the Arctic Basin, the ocean dynamics at mesoscale and submesoscale under sea ice are poorly quantified and understood. Here, we analyze comprehensive datasets from Ice Tethered Profilers and moorings from the Beaufort Gyre Observing System spanning the period 2004–2019 in order to characterize the space and time variations of the (sub)mesoscale flow. In seasonally ice-covered regions, the dynamics in the surface layer is largely determined by the presence of sea ice, with an increased eddy kinetic energy and numerous eddies in summer. Beyond these regions, the influence of the sea ice conditions on the first order dynamics is less clear. A wavenumber spectra analysis of observations at the surface and at depth under the sea ice pack reveals that a large variety of regimes can be found, independently of the time and space variations of the sea ice conditions. Focusing on a census of individual eddies, and their potential signature in sea ice, we found that around 500 eddies can be detected in the subsurface layer over 2004–2019, including both submesoscale (radius between 3 and 10km) and mesoscale (up to 80 km) structures. Based on simple scaling calculations, we quantify the dynamical or thermodynamical signature that these eddies may imprint at the surface. While they do not induce any significant heat flux and subsequent sea ice melt, subsurface eddies can induce a dynamic height anomaly of the order of a few centimetres, resulting into a surface vorticity anomaly strong enough to impact sea ice locally.

Key Points

We use large datasets of in situ observations to document the Arctic dynamics at meso and submeso scales over 16 years

In the ice pack, the distribution of oceanic energy across scales is not determined at first order by the heterogeneity in sea ice conditions

Subsurface eddy can potentially imprint a signature in sea ice drift and vorticity

Plain Language Summary

The presence of sea ice in the Arctic is thought to play a role for the determination of the ocean circulation, in particular for the small scale energetic eddies. Here, we revisit 16 years of temperature, salinity and velocity observations from moorings and autonomous profilers drifting with sea ice to characterize the spatio-temporal variations of the turbulent flow. On the one hand, there is a clear separation between the ice covered and the ice free regions: at first order the presence of sea ice damps the turbulence and dissipate surface eddies. Yet, under the sea ice pack, we find a large variety of turbulent regimes, that does not appear to be directly determined by the sea ice conditions. On the other hand, eddies propagating at depth under sea ice can potentially impact the sea ice, by exerting a stress strong enough to modify the sea ice drift and vorticity locally.