Internal tide generation in the Gulf of Mexico and its impact on the Yucatan Channel and Florida Strait exchanges

Baroclinic tides play an important role in the transfer of energy into the ocean interior. It is estimated that about 1/3 of the barotropic tidal energy is lost in the open ocean. In the case of narrow channels, it can be an important contributor to the energy flux and oscillating transports . Therefore, tides can constitute an important forcing for the regional circulation that should be taken into account when developing numerical simulations. In particular for the Gulf of Mexico, there is a need to estimate the impact of the barotropic and baroclinic tides on the circulation variability.

The contribution of internal tides to the transport variability in the Yucatan Channel and Florida Strait is observed from a series of moored current meters. The dataset covers the whole channel sections, for the period from July 2012 to July 2015. It reveals a dominance of baroclinic diurnal and semidiurnal tides in the Yucatan Channel and Florida Strait respectively, with maximum amplitudes in deep waters. A one-year numerical simulation with the ROMS model is used to explore the energy conversion from barotropic to baroclinic tides and its effect on the Gulf’s interior and the Yucatan Channel and Florida Strait exchanges. Towards the development of a reanalysis of the Gulf of Mexico ocean state, a study of the impact of the inclusion of the tidal forcing to the numerical model is conducted. Although the barotropic tides are expected to play a minor role in the regional circulation, the generation of internal tides in the eastern Gulf constitutes a substantial forcing for the observed circulation variability. Considering both the data and the model results it is shown that internal tides generation represents an important source of variability for the transport in and out of the Gulf of Mexico, and has potential impact on mixing in the Loop Current region.