Properties of internal tides observed in the southwestern part of the East Sea

Abstract

We investigated the properties of internal tides observed near the continental slope of the southwestern East/Japan Sea using two sets of 25-hr long hourly CTD and LADCP profiles and numerical simulations. The profiles spanned the whole water column from the surface to about 260m depth. A semi-diurnal internal tide was strongest below the main thermocline (150-200m) where the 5ºC isotherm was displaced more than 50m. The Richardson numbers were low (0-0.25) in layers where large vertical displacements were observed, suggesting internal tide induced mixing. Numerical simulations using an idealized vertical 2.5-dimensional numerical model based on the ROMS revealed that the semi-diurnal internal tide was predominantly generated on the continental slope. By analyzing the observed data and model results, we were able to investigate the internal tide generation mechanism and its impact on ocean mixing in this regioner column from the surface to about 260m depth. A semi-diurnal internal tide was strongest below the main thermocline (150-200m) where the 5ºC isotherm was displaced more than 50m. The Richardson numbers were low (0-0.25) in layers where large vertical displacements were observed, suggesting internal tide induced mixing. Numerical simulations using an idealized vertical 2.5-dimensional numerical model based on the ROMS revealed that the semi-diurnal internal tide was predominantly generated on the continental slope. By analyzing the observed data and model results, we were able to investigate the internal tide generation mechanism and its impact on ocean mixing in this region