Transfers of heat, energy and gases through the ocean surface mixed layer are extremely complex and spatially heterogeneous. The discontinuous and dynamic sea ice cover, and the occurrence of eddies, fronts and filaments at the kilometre-scale, are important heterogeneities which regulate the thickness and properties of the mixed layer. Large discrepancies in mixed layer depths are found among climate models used for IPCC scenarios, partly due to a misrepresentation of the integrated effect of these heterogeneities. This limits the usefulness of climate models in assessing the impacts of future climate change on European climate and marine ecosystems. 

MEDLEY (MixED Layer hEterogeneitY) will further our understanding of mixed layer heterogeneity in the North Atlantic a hotspot of anthropogenic CO2 storage, and in the rapidly warming Arctic Ocean. 

The core objectives of MEDLEY are: 

– to evaluate the spatial hererogeneity of fluxes and of the processes controlling the ocean mixed layer 

–  to improve the representation of the transfers through the mixed layer in climate models by taking this heterogeneity into account 

The project integrates state of the art observational datasets and basin scale ocean models resolving the kilometre scale, an innovative sea-ice model, and the latest generation of climate models with an eddying ocean component. Building on interdisciplinary collaborations between its members, MEDLEY will take advantage of the most recent data analysis (e.g., machine-learning based classification).

We will focus on NEMO, the Nucleus for European Modelling of the Ocean, a European modelling platform used by all MEDLEY members. MEDLEY aims at a better tuning and consistency of mixed layer representation (parameterizations) in NEMO-based climate models, gained through multi-scale modelling and validation by recent high-resolution observations.


Organisation Acronym Country
Laboratoire d’Océanographie Physique et SpatialeLOPS – CNRSFRANCE
Institut des Géosciences de l’EnvironnementIGEFRANCE
Université Catholique de Louvain la NeuveUCLouvainBELGIUM
Fondazione Centro Euro-Mediterraneo sui Cambiamenti ClimaticiCMCCITALY
Nansen Environmental and Remote Sensing CenterNERSCNORWAY
Institute of Oceanology of the Russian Academy of SciencesIORASRUSSIA


Joint programming initiatives – JPI ocean and JPI Climate