Internal wave climate near the coast of nortwest Africa during JOINT-I

Abstract

Abstract Current meter measurements from six stations off the coast of northwest Africa are analysed. Decomposition of the data using empirical orthogonal eigenfunctions shows that in depths shallower than 800 m a significant part of the internal wave energy resides in first mode waves that propagate shoreward. Examination of the energy flux and energy density of these waves indicates that: (1) the origin of the internal wave energy appears to be the deep ocean; (2) the energy density of the interval waves increases shoreward in the deep coastal waters subject to a constant energy flux requirement; (3) the energy density in shallow coastal waters is nearly saturated, i.e. the maximum amplitudes are limited by a finite depth and thus the local energy levels are determined by the local Vasala frequency and depth; (4) the energy flux is largely dissipated rather than reflected back out to the deep sea.