High amplitude internal tidal waves generated over an underwater sill in the Gulf of California

Abstract

The first in-situ measurements of the internal tidal waves generated at San Esteban sill in the archipelago of the large islands of the Gulf of California (GC), Mexico, show that the semidiurnal barotropic tide generates nonlinear internal tides which propagate to the North (South) during the ebb (flood) of the barotropic tidal wave, resulting in significant changes in temperature and salinity to depths of 150 m. During their propagation, these internal tidal waves disintegrated into groups of short, high amplitude, strongly nonlinear waves. The leading edges of these wave groups had vertical displacements reaching 50–80 m, horizontal wavelengths about 1 km, and phase speeds of about 1.2 m s−1. The POM numerical model (Princeton Ocean Model) was used to explore the processes in this area and results were in good agreement with the instrumental data. The internal tidal waves generated from the sill resulted in strong vertical and horizontal mixing, which most likely contributes to the high productivity of this area of the GC (Gaxiola-Castro, 1992, Ruvalcaba-aroche, 2019).