The Internal Tide Off Southern California

Abstract

Abstract : The internal tide may well form an important link in the chain of events between the forcing of the surface tide and the eventual dissipation of internal waves by viscous forces. Two issues related to this chain of events are addressed. One is the directionality of the internal tide off the coast of California and the other is the widespread occurrence of semi-diurnal tidal harmonics in internal wave spectra. It is commonly accepted that the internal tide derives its energy from the forcing of isopycnal surfaces over topographic features by the surface tide. Accordingly, steep continental slopes like the Patton escarpment should be important generation regions. The directionality of the internal tide off California and hence the importance of the Patton escarpment as a source are assessed by analyzing data collected by the R/P FLIP. The results indicate that the direction of propagation of the internal tide is variable and that the majority of its energy does not appear to originate at the escarpment.