Monitoring of Oceanic Internal Tides Using Fibre Optic Telecommunication Cables

Abstract

Ocean mixing plays a crucial role in the Earth’s climate as it balances the meridional overturning circulation that buffers global warming. Quantifying mixing is challenging because energy enters the ocean at basin-scale but it dissipates at cm-scale over the vast ocean. One common element in the cascade of energy towards small scales is the transfer of energy to internal waves, which may turn unstable and drive much of the ocean mixing. Energy transfer to the internal wave field is largely enhanced through flow interactions with topography. Observations of wave-topographic interactions are, however, scarce and its mechanistic understanding comes mainly from idealized process ocean studies, which lack a direct benchmark against nature. We present novel observations of wave-topographic interactions at unprecedented spatiotemporal resolution. The new data has been gathered using fibre-optic cables by means of a revolutionary technology developed in the field of seismology. The potential of these observations to identify ocean-mixing hotspots remains, however, unknow. To shed light on this, we use numerical advanced modelling, the basis of which is presented here. The model is semi-spectral with open boundaries allowing to create a suite of nested simulations that resolve the transfer of energy from the large-scale (hundreds of km) down to turbulencelength scales (cm). The proposed approach integrates a variety of approaches and disciplines and could eventually be implemented at global scale with the aim to better close energy budgets and improve mixing parametrizations in climate change models