On horizontal coherence and internal wave propagation in the North Sea

Abstract

Horizontal coherence computations from a closely spaced four mooring array in the northern North Sea are presented. By use of the co- and quadrature spectral functions of the temperature fluctuations at the four moorings the propagation direction of the internal tide and a shorter period wave have been determined. The internal tidal wave is shown to travel towards north almost against the direction of the surface tide. The horizontal wave-lengths of the thermocline waves approximately coincide with the values determined from the density distribution.