An examination of the radiative and dissipative properties of deep ocean internal tides

In this study, the energy flux and energy dissipation of deep ocean internal tides are examined. Properties of the internal tide from two distinct generation regions are contrasted: the Mid-Atlantic Ridge (MAR) and the Hawaiian Ridge. Considerable differences are noted for the baroclinic energy flux, 〈 u ′ p ′ 〉 , radiated from each site. Radiation from the MAR is relatively rich in high modes, with an energy flux spectral peak at mode 5 and modes 10 and greater accounting for 40% of the total flux. In contrast, Hawaiian Ridge radiation is dominantly composed of modes 1 and 2, with modes 10 and greater accounting for less than 5% of the total flux. Depth integrated energy flux levels are O ( 1 ) kW m - 1 at the MAR site, and O ( 10 ) kW m - 1 at the Hawaiian Ridge. Despite these differences, observed turbulent dissipation rates at these sites are similar in magnitude and depth dependence. Decay scales, estimated as L ε = ( ∫ - H 0 u ′ p ′ d z ) / ( ∫ - H 0 ρ 0 ε d z ) , range from O ( 100 ) km to O ( 1000 ) km . The mean decay scale based on the MAR data is 230 km, a factor of 3 smaller than at the Hawaiian Ridge site. We demonstrate that the dissipation level scales with the energy flux available in the high modes, which is comparable at both sites, rather than the total energy flux.