Deterministic and stochastic parameterizations of kinetic energy backscatter in the NEMO ocean model in Double-Gyre configuration

Abstract

Abstract Eddy-permitting numerical ocean models often resolve mesoscale turbulence only partly, which leads to underestimation of eddy kinetic energy (EKE). Mesoscale dynamics can be amplified by using kinetic energy backscatter (KEB) parameterizations returning energy from the unresolved scales. We consider two types of KEB: stochastic and negative viscosity ones. The tuning of their amplitudes is based on a local budget of kinetic energy, thus, they are "energetically-consistent" KEBs. In this work, KEB parameterizations are applied to the NEMO ocean model in Double-Gyre configuration with an eddy-permitting resolution (1/4 degree). To evaluate the results, we compare this model with an eddy-resolving one (1/9 degree). We show that with the KEBs the meridional overturning circulation (MOC), meridional heat flux, and sea surface temperature (SST) can be significantly improved. In addition, a better match has been found between the time power spectra of the eddy-permitting and the eddy-resolving model solutions.