Tidal Modulation of Energy Dissipation Routes in the Gulf Stream

The Gulf Stream (GS) is a powerful ocean current that is instrumental in regulating the global climate. While a correct reproduction of GS dynamics is contingent on an appropriate representation of energy dissipation, the specific role of tides in dissipation pathways of the wind-driven circulation is not well understood. Here, we present evidence, using high-resolution ocean simulations (similar to 2 km grid spacing), that ocean tides, by generating internal gravity waves, increase the forward cascade of energy in the GS region. This effect is greatest in summer, when the intensity of internal tides increases. However, the dissipation route associated with the forward energy cascade remains an order of magnitude weaker than frictional dissipation near the surface and bottom boundaries. Understanding the dynamics of the Gulf Stream (GS) is essential because of its influence on global climate and ocean circulation. Previous studies have shown that a realistic representation of this region using oceanic models depends on a correct representation of the energy balance and, in particular, how the system loses energy. Energy can be dissipated at the boundaries (bottom and surface ocean) and in the interior, but how tides affect energy dissipation in the GS is unknown. In this study, we found that the interior dissipation increases when tides are included, but this route remains small compared to the energy dissipated at the boundaries. Internal tides modulate the Gulf Stream (GS) turbulent cascade through wave-flow interactionExternal tides increase bottom drag of subtidal circulation in the deep ocean. intensifies the forward cascadeTide-induced increased dissipation pathways reduce GS mesoscale activity

Automated summary

This article investigates the impact of tides on energy dissipation in the Gulf Stream. The research finds that tides increase the forward cascade of energy in the region by generating internal gravity waves. However, this effect is much weaker compared to frictional dissipation at the boundaries.