Ocean Mixing in the Arctic: Case study at the North Pole Environmental Observatory

Ocean mixing plays a pivotal role in climate variability and change. Despite its importance, mixing is the most uncertain component of modern ocean general circulation models. Field measurements covering both the small (turbulent) scales and conventionall y measurable larger scales aid to understand the link between the energy containing scales and the ultimate dissipation and to improve the parameterization of this link. The data are scarce, especially in the Arctic, and urgent field measurements are need ed. The Arctic ice cover depends on a delicate heat balance in which the magnitude and distribution of the oceanic vertical heat flux is important. The amount and spatial distribution of thermal and mechanical forcing, ocean stratification, internal wave activity and turbulent mixing have significant impact on this vertical heat flux. With this motivation, the proposed project aims to investigate ocean mixing during the drift of the North Pole Environmental Observatory based at Borneo Ice Camp (approxim ately 89degN), through field observations and process studies. We propose to conduct field work in spring of 2007 and 2008 during the International Polar Year period including time series of fine scale velocity and microstructure profiles from Borneo and vertical profiles of velocity and microstructure at stations occupied by a helicopter along transects across the Lomonosov Ridge. The proposed sampling region encompasses a variety of bathymetric regimes covering abyssal flats to ridges with a high likeli hood of tide-topography interactions and internal wave generation. During the course of the drift we expect to sample internal wave activity, eddies, double-diffusive layering and variations in Atlantic Water temperature and velocity.