Abstract
Oceanic mesoscale eddies play an important role in preconditioning and
restratifying the water column before and after mixing events, thereby
affecting deep water formation variability. In the Labrador Sea, where
deep convection occurs regularly, observations and models indicate a
complex interplay of turbulence and associated tracer fluxes. Results
from a realistic eddy-resolving (~5 km local horizontal
resolution) ocean model in quasi-equilibrium (~300 years
integration) suggest that small-scale temperature fluxes due to
turbulent potential to kinetic energy conversion are the main driver of
mixed layer restratification during deep convection triggered through
atmospheric forcing. In addition to these baroclinic instabilities,
buoyant water masses must be provided by the boundary current, where
barotropic turbulence is equally important. Only acting together, the
destabilizing forcing can be balanced. In a low-resolution control
simulation (~20 km) the modeled turbulence is strongly
reduced and the associated modeled and parameterized heat fluxes too
weak to increase stratification.