Variability of Eddy Kinetic Energy in the Eurasian Basin of the Arctic Ocean Inferred From a Model Simulation at 1-km Resolution

Mesoscale eddies play an important role in driving the dynamics of the Arctic Ocean. Understanding their behavior is crucial for comprehending the ongoing changes in the region. In this study, by using a novel decade-long simulation at 1 km resolution with the unstructured-mesh Finite volumE Sea ice-Ocean Model, we evaluate the spatial and temporal variability of eddy kinetic energy in the Eurasian Basin. We find that monthly, annual, and interannual variability of EKE near the surface is predominantly influenced by changes in sea ice cover, while the eddy activity at deeper depth, being shielded from the surface by ocean stratification, is more strongly influenced by local baroclinic energy conversion. Moreover, our research demonstrates that eddies in the Eurasian Basin can transport ocean heat from the Atlantic Water layer toward sea ice and cause local basal melting in the order of about 20 cm per month even in wintertime. Our study suggests that eddy activity in the Arctic Ocean will strengthen along with future sea ice decline, and that the impact of ocean heat of the Atlantic Water layer on sea ice retreat may become prominent. Mesoscale eddies are swirling currents that are generally considered the "weather" of the ocean. They can be found everywhere in the ocean and are crucial for understanding many processes such as the transport of heat and salt, the structure of ocean stratification, but also the distribution of nutrients that influence the biological system from algae blooms to micro and macro fauna. Distinct from major eddies in lower latitudes, most eddies in the Arctic Ocean are only about 10 km in diameter. This makes it incredibly hard to simulate them in numerical models because a very high spatial resolution is needed to adequately represent them. In this study we use a simulation with 1 km horizontal resolution to analyze the role of eddies in the Eurasian Basin of the Arctic Ocean and to understand what drives their variability. We found that the dynamics differ greatly between the surface and deeper water layers, with the surface being influenced strongly by sea ice cover, while the deeper layer is shielded from this effect by the stratification. We have also shown that eddies can pump warm water from the Atlantic Water layer up to the mixed layer, thus melting sea ice even in winter. Mesoscale eddies in the Eurasian Basin can bring ocean heat from the Atlantic Water layer to sea ice and cause basal melting even in winter Variability of surface eddy kinetic energy is mainly controlled by sea ice cover Eddy activity at depth is mainly controlled by baroclinic instability and ocean stratification