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 ?h ? 200?400 m2 s?1, and a vertical transfer coefficient bounded away from zero, with ?? + (?f?2/N?2)Kh ? 2.5 ± 0.3 ? 10?3 m2 s?1 in contrast to ?? + (?f?2/N?2)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.