The ocean surface mixed layer mediates the transfer of heat, freshwater, momentum and trace gases between atmosphere, sea ice and ocean. Thus, the mixed layer transfer function must be represented accurately in climate models, especially in the North Atlantic and in the Arctic oceans which are, respectively, hotspots of anthropogenic CO2 storage and warming. Large discrepancies in mixed layer depths are found in low resolution CMIP5 models, in part because these models do not parameterize properly the spatial heterogeneities induced by the presence of a discontinuous and very dynamic sea ice cover, mesoscale eddies and submesoscale fronts and filaments at the kilometer-scale. The region of interest ranging from the North Atlantic to the Arctic ocean is especially relevant to future changes of the European climate. MEDLEY brings together state of the art observational datasets, groundbreaking submesoscale-resolving basin scale models, an innovative sea-ice model, and the latest generation of climate models with an eddying ocean component participating in the HighResMIP intercomparison. By pooling their expertise, MEDLEY members will produce the most complete evaluation of the mixed layer dynamics in state of the art climate models, from the North Atlantic to the Arctic ocean. MEDLEY will improve our understanding of the relationship between air- sea fluxes and mixed layer properties, taking into account the mediation of the fluxes induced by the fractured sea ice cover. MEDLEY will evaluate the effect of spatial heterogeneities on mixed layer properties, including currents and kinetic energy, as well as the relationship between the mixed layer and the interior through the stratified transition layer. Building on interdisciplinary collaborations of its members, MEDLEY will take advantage of the most recent data analysis methods (e.g., machine learning-based classification).
Project leader: Einar Örn Olason
Institution: STIFTELSEN NANSEN SENTER FOR MILJØ OG FJERNMÅLING