On constraining the mesoscale eddy energy dissipation time-scale

TL;DR

This paper introduces a simple, computationally inexpensive method to estimate the lower bound of the mesoscale eddy energy dissipation time-scale in the ocean, highlighting key regions of energy transfer.

Contribution

It provides a novel, physically plausible lower bound estimation technique for the mesoscale eddy energy dissipation time-scale using inverse calculations and high-resolution simulation data.

Findings

Shortest dissipation time-scale in the Southern Ocean and Western Boundaries

Regions of high baroclinic activity correlate with shorter time-scales

Method offers a baseline for further ocean energetics studies

Abstract

A physically plausible lower bound on the spatially varying geostrophic mesoscale eddy energy dissipation time-scale within the ocean, related to the geographical energy transfer rate out of the geostrophic mesoscales, is provided by means of a simple and computational inexpensive inverse calculation. Data diagnosed from a high resolution global configuration ocean simulation is supplied to a parameterized model of the geostrophic mesoscale eddy energy, from which the dissipation time-scale results as a solution to an optimization calculation. We find that the dissipation time-scale is shortest in the Southern Ocean, in the Western Boundary Currents, and on the western boundaries, consistent with the expectation that these regions are notable sites of baroclinic activity with processes leading to energy transfer out of the geostrophic mesoscales. Although our solution should be interpreted as a lower bound given the assumptions going into the calculation, it serves as an important physically consistent base line reference for further investigations into ocean energetics, as well as for an intended inference calculation that is more complete but also much more complex.