Internal Tide Attenuation in the North Pacific

Abstract

Multisatellite altimetry and an eddy-resolving model with tides are used to quantify the attenuation of the mode-1 M2 internal tide as it propagates from three major sources in the North Pacific. The model is used to correct the altimetric fluxes for the nonstationary signal that altimeters cannot detect. Because internal tides in the North Pacific are highly stationary, these corrections do not materially impact the decay rate estimates. Fluxes are integrated in wedges extending from the sources to account for interference and radial spreading. Observed attenuation rates are consistent with e-folding scales between 750 and 3,000 km, suggesting weak dissipation rates (≤10−10 W/kg or 0.75×10−3 W/m2) compared to typical open-ocean turbulence levels, implicating near-inertial waves and higher-mode internal tides in providing the balance of the dissipation in the ocean interior.