Near-Inertial Wave - Eddy Interactions in Realistic High Resolution Simulations of the North Atlantic Subpolar Gyre

Kaushik Srinivasan, University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, Roy Barkan, Tel Aviv University, Tel Aviv, Israel, James C. McWilliams, University of California Los Angeles, Los Angeles, CA, United States and Jonathan Gula, Université de Bretagne Occidentale, Laboratoire d'Océanographie Physique et Spatiale (UBO, CNRS, Ifremer, IRD), Plouzané, France
Abstract:
Recent theories and idealized numerical simulations have suggested the possibility for substantial energy exchanges between mesoscale eddies, submesoscale fronts and filaments, and near-inertial internal waves (eddy-NIW interactions). In this work we utilize realistic submesoscale-resolving numerical simulations in the North Atlantic Subpolar Gyre and quantify the effects of eddy-NIW interactions on the spatial and temporal energy cascades. We apply a spatio-temporal coarse-graining filtering approach to numerical simulations with and without wind-forced NIWs and demonstrate that eddy-NIW interactions stimulate a forward eddy kinetic energy (EKE) cascade to dissipation. Specifically, we show that the volume averaged EKE transfer induced by NIWs is as high as 25 % of the total EKE transfer, and that it is strongest in the upper ocean. We further discuss the seasonal cycle of eddy-NIW interactions and the relative importance of mesoscale eddies vs. submesoscale fronts and filaments to the energy exchanges.