Internal Tide Radiation from Mendocino Escarpment

Abstract

Abstract Strong semidiurnal internal tides are observed near Mendocino Escarpment in full-depth profile time series of velocity, temperature, and salinity. Velocity and density profiles are combined to estimate the internal tide energy flux. Divergence of this flux demonstrates that its source is the barotropic tide interacting with the escarpment. A baroclinic energy flux of 7 kW m−1 radiates from the escarpment, corresponding to 3% of the 220 kW m−1 fluxing poleward in the surface tide. Energy and energy flux are concentrated in packets that emanate from the flanks of the ridge surmounting the escarpment and one site ∼90 km north of the escarpment. Coherent beamlike structure along semidiurnal ray paths remains identifiable until the first surface reflection. Beyond the first surface reflection north of the escarpment, the energy flux drops by 2 kW m−1 and beams are no longer discernible. Turbulence, as inferred from finescale parameterizations, is elevated by over two orders of magnitude relative to th...