Dynamics of Internal Tides Over a Shallow Ridge Investigated With a High‐Resolution Downscaling Regional Ocean Model. Issue 8 (16th April 2018) - Masunaga, Eiji
Abstract: This study investigates the dynamics of tidally induced internal waves over a shallow ridge, the Izu‐Ogasawara Ridge off the Japanese mainland, using a downscaled high‐resolution regional ocean numerical model. Both the Kuroshio and tides contribute to the field of currents in the study area. The model results show strong internal tidal energy fluxes over the ridge, exceeding 3.5 kW m −1, which are higher than the fluxes along the Japanese mainland. The flux in the upstream side of the Kuroshio is enhanced by an interaction of internal waves and currents. The tidal forcing induces 92% of the total internal wave energy flux, exhibiting the considerable dominance of tides in internal waves. The tidal forcing enhances the kinetic energy, particularly in the northern area of the ridge where the Kuroshio Current is not a direct influence. The tidal forcing contributes to roughly 30% of the total kinetic energy in the study area. Plain Language Summary: Internal waves are ubiquitous phenomena in oceans, and they play a significant role in global ocean circulations and climates. However, details of internal waves have not been understood well due to limitations of field surveys. This study investigates the dynamics of tidally induced internal waves (internal tides) over a shallow ridge using a high‐resolution numerical simulator with a horizontal resolution of 1 km. The model results show that tidal forcing dominates in internal wave energy over the ridge, and an interaction of internal waves and currents enhances internal waves in the upstream side of the Kuroshio. Internal tides explain 92% of the total internal wave flux over the ridge. Tides generate roughly 30% of the total kinetic energy in the study area. Key Points: Internal tidal dynamics are investigated with a high‐resolution numerical model Tidally induced internal waves explain 92% of the total internal wave flux over the Izu‐Ogasawara Ridge, off the Japan mainland Approximately 30% of the total kinetic energy is excited by tidal forcing over the ridge