Internal tides observed to be coherent in shelf sea

Abstract

Internal tides, waves with tidal frequencies below the ocean's surface, contribute to ocean mixing. They are common in shelf seas, shallow marginal seas located on the continental shelf. These tides are believed to be coherent over hundreds of kilometers before they decay, but spatial coherence of internal tides had not been observationally confirmed in shelf seas. Inall et al. conducted in situ observations of internal tides over the continental shelf of the Celtic Sea. They found that the internal tide was coherent over more than 170 kilometers, about five wavelengths. The observations, which provide the first in situ evidence of internal tide coherence over multiple wavelengths in a shelf sea, could be useful for improving models of mixing in shelf seas. (Geophysical Research Letters, doi:10.1029/2011GL049943, 2011)