Mesoscale Eddy-Internal Wave Coupling. Part II: Energetics and Results from PolyMode

Abstract

The issue of internal wave-mesoscale eddy interactions is revisited. Previous observational work identified the mesoscale eddy field as a possible source of internal wave energy. Characterization of the coupling as a viscous process provides a smaller horizontal transfer coefficient than previously obtained, with vh ≅ 50 m2 s-1 in contrast to vh ≅ 200-400 m2 s-1, and a vertical transfer coefficient bounded away from zero, with vv + (f2/N2)Kh ≅ 2.5 ± 0.3 × 10-3 m2 s-1 in contrast to vv + (f2/N2)Kh ≅ 0 ± 2 × 10-2 m2 s-1. Current meter data from the Local Dynamics Experiment of the PolyMode field program indicate mesoscale eddy-internal wave coupling through horizontal interactions (i) is a significant sink of eddy energy and (ii) plays an O(1) role in the energy budget of the internal wave field. © 2010 American Meteorological Society.