Impact of the mesoscale dynamics on the internal tide lifecycle in the North Atlantic

In the ocean, internal tides (internal waves generated by the interaction of the barotropic tide and the irregular bathymetry) interact in various ways with the other types of motion, in particular the mesoscale currents.
These interactions disrupt the life cycle of the internal tide, from its generation to its dissipation.
These effects include the loss of coherence of the internal tide -- corresponding to a phase unlocking with the parent barotropic tide, which is essentially regular in the deep ocean -- and cross-scale energy transfers. 
In this study, we investigate the effect of mesoscale flow on the semidiurnal internal tide propagation using outputs from a high-resolution realistic numerical simulation of the North Atlantic. 
Using a vertical mode decomposition framework, we identify and quantify the mechanisms that affect the internal tide: in particular, we show that advection by the mean flow leads to an average transfer of energy from low modes to high modes -- hence large to small scales --, potentially contributing to the dissipation of the internal tide by "feeding" wave breaking. 
We also quantify the loss of internal tide coherence due to these terms and discuss them in different regions with typical flow/internal tide configurations.