Separating energetic internal gravity waves and small-scale frontal dynamics

Oceanic fronts with lateral scales less than 20 km are now known to be one of the major contributors to vertical heat fluxes in the global ocean, which highlights their potential impact on Earth’s climate. However, frontal dynamics with time scales less than one day, whose contribution to vertical heat fluxes is thought to be significant, are obscured by energetic internal gravity waves. In this study, we address this critical issue by separating internal gravity waves and frontal dynamics using an approach based on their respective vertical scales of variability. Results using a numerical model with a horizontal grid spacing of 500 m confirm that it is possible to recover frontal dynamics at short time scales as well as associated intense vertical velocities and vertical heat fluxes. This opens up new possibilities for a more accurate estimation of the vertical exchanges of any tracers between the surface and the ocean interior.