Semidiurnal internal tide incoherence in the equatorial Pacific

摘要: The jets in the equatorial Pacific Ocean of a realistically forced global circulation model with horizontal resolution 1/12.5° cause strong loss phase coherence semidiurnal internal tides that propagate equatorward from French Polynesian Islands and Hawaii. This is quantified baroclinic energy analysis, which semidiurnal-band terms are separated into coherent, incoherent, cross terms. For time scales longer than year, coherent flux approaches zero values at equator, while total ∼500 W/m. variability incoherent compared internal-tide travel-time variability, based on along-beam integrated speeds computed Taylor-Goldstein equation. monthly mean agrees well speed inferred steric sea surface height phases extracted plane-wave fit technique. On scales, beams attributed to vertically sheared background flow associated tropical instability waves. an annual scale, effect stratification equal or greater importance shear coherence. In simulations, low-frequency do not noticeably enhance dissipation tide, but merely decohere scatter it.