Model estimates of M₂ internal tide energetics at the Hawaiian Ridge

Abstract

A primitive equation model is used to examine the structure and energetics of M 2 internal tides generated at the Hawaiian Ridge. Recent estimates based on altimeter data suggest that 20 GW of barotropic tidal dissipation occurs at the ridge, with conversion to internal tides believed to be the dominant dissipation mechanism. The model simulates an internal tide that accounts for 9.7 GW of radiated energy away from the ridge in the northeast and southwest directions. The strongest generation occurs at three sites where enhanced barotropic currents flow across elongated topographic features. The depth‐integrated baroclinic energy flux and energy densities at these sites are on the order of 10 4 W m −1 and 10 4 J m −2 , respectively. A modal decomposition indicates that 62% of the outgoing energy flux is accounted for by the first internal mode, 15% is accounted for by the second mode, and less than 5% is accounted for by each subsequent higher mode. The tidal dissipation due to bottom friction along the ridge is estimated to be 0.1 GW. The level of turbulent dissipation near the ridge owing to tidal energy conversion remains to be determined to assess fully the barotropic‐baroclinic energy budget.