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

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 Väsälä frequency and depth; (4) the energy flux is largely dissipated rather than reflected back out to the deep sea.