Resonant Diurnal Internal Tides in the North Atlantic: 2. Modeling

Abstract

AbstractAn unconstrained global ocean simulation for 2020 supports past observations of diurnal internal tides by acoustic tomography during the 1991–1992 Acoustic Mid‐Ocean Dynamics Experiment in the Western North Atlantic. Explicitly representing the tides, the simulation reproduces the functional form and resonant state of K1 and O1 internal‐tide standing waves, while providing a more realistic physical picture of them. The tomographic data were used to predict the tides in 2020. Not surprisingly, the characteristics of the barotropic and internal tides of the unconstrained simulation deviate from observations. The simulated barotropic tidal currents have excessive, irregular amplitude and lead the acoustic tidal predictions by about 2 hr. While internal‐tide phase coherence is apparent, the simulated internal‐tide variations were irregular in amplitude and phase, unlike the observations. The tomographic tidal measurements therefore provide a quantitative benchmark for improved model representation of tides, internal tides, and dissipation.