Frequency-Based Correction of Finescale Parameterization of Turbulent Dissipation in the Deep Ocean

Abstract

AbstractAmong the existing finescale parameterizations of turbulent dissipation rates, the Gregg–Henyey–Polzin (GHP) parameterization is thought to produce the most accurate estimates of turbulent dissipation rates since it takes into account distortions from the Garrett–Munk (GM) spectrum using the shear/strain ratio . The GHP parameterization, however, applies the single-wave approximation to infer turbulent dissipation rates in broadband internal wave spectra with a multiplication factor up to 3, so as to adjust the predicted value at to the theoretical value for the GM spectrum. Because of this multiplication, the GHP parameterization overestimates the dissipation rates for . This study explores the possibility of further improvements of the GHP parameterization and reformulates the parameterization to make it applicable to both 1) a narrowband frequency spectrum characterized by a prominent near-inertial peak () and 2) a broadband frequency spectrum like the GM (). Furthermore, the performance of the modified parameterization is assessed in comparison with the GHP parameterization using the available microstructure data obtained near prominent topographic features in the North Pacific.