Winter Mixed Layer Restratification Induced by Vertical Eddy Buoyancy Flux in the Labrador Sea

Abstract

AbstractNumerical model studies have shown that the lateral buoyancy transports from eddies restratify the convection region in the Labrador Sea. However, restratification by vertical motion during and after convection has been underestimated. Here we use a model with 1°/60° resolution which can resolve mesoscale and submesoscale motions, and find that negative feedback that includes the generation of vertical eddy buoyancy flux (VEBF) committed to restratify the mixed layer. In winter, VEBF compensates for nearly half of the surface buoyancy loss and is as important as the lateral buoyancy fluxes in the eddy‐rich region, which results in restraining the development of deep convection. During this period, the surge of VEBF was due to seasonally enhanced frontogenesis, mixed layer instability and the interaction between strong surface winds and eddies on a 10‐day timescale. Therefore, well parameterizing VEBF is important in improving the representation of the deep convection in coarse‐grid climate models.