A summer lead in the Arctic Ocean during the SHEBA year

The Surface Heat Budget of the Arctic Ocean (SHEBA) Project took place from October 1997 - October 1998 and provided an extensive ensemble of data regarding mass, energy, heat and turbulent fluxes between the atmosphere-ice-ocean interfaces.

Some of those fluxes together with measured ice-pack characteristics (thickness and drift) are used here to force a layered ocean model, while vertical profiles of temperature, salinity and velocities are used as initial conditions.

During late July of 1998, extensive atmospheric warming and weak wind-forcing led to the accumulation of very fresh water at the surface of a lead (i.e. an opening in the ice cover) through surface, bottom and lateral ice-pack melting. A strong wind event that followed resulted in the fresh water being mixed vertically and ``flushed-out'' into the ocean column below.

Two mixing schemes are used here to reproduce numerically the event. The first mixing scheme, Local Turbulence Closure (LTC) by McPhee, has been tailored for ice-covered oceans but simulates only mixed layer and pycnocline response to surface and local forcing. The Canuto/GISS scheme addresses the whole water column but until now it has only been used to study mixing in mid-latitudes.