Frictional Formulations in Numerical Ocean Models and Their Effect on Simulated Acoustic Fields

Abstract

Abstract This study has examined the effects of frictional formulations in numerical ocean models on simulated acoustic fields. Starting from the same initial state of a perturbation to a simple linear front, comparisons are made of numerically simulated frontal environments, with biharmonic and Laplacian (harmonic) friction operators, to describe subgrid-scale mixing. Using a just stable harmonic simulation as a “control” for the effects of small-scale processes (wavelength of order 10 km), comparisons of the energetics and spectra of the simulated environments have confirmed the effect of biharmonic friction in suppressing small-scale motion while maintaining the mesoscale. However, a new result concerns the impact of this scale selectivity on simulated underwater acoustic fields and the possible consequences of this for ocean forecast models and acoustic tomography applications. Acoustic effects have been quantified in terms of the differences in predicted sound intensity levels between harmonic and bi...