Observations of the Horizontal Interactions between the Internal Wave Field and the Mesoscale Flow

Abstract

Momentum and energy transfers from the mesoscale horizontal velocity shear to the internal wave field have been deduced from an analysis of a closely spaced, 25 km, moored current-meter array. The correlation between the low-frequency horizontal shear and internal-wave-field continuum effective stress implies a significant horizontal eddy viscosity of O (10⁶ cm² s⁻¹), somewhat larger than predicted by Müller (1976). A simple steady-state energy balance for the internal wave field using the observed correlation between the internal wave kinetic energy and the square of the low-frequency shear implies a 10-day relaxation time for the internal-wave Acid and a combined vertical viscosity and horizontal diffusivity not significantly different from zero. These estimates are within the experimental uncertainty of previous observational analyses.