Vertical mixing schemes play a significant role in affecting mixing processes, turbulence, and surface and sub-surface properties in the ocean. The performance of two vertical mixing schemes, K-Profile Parameterization (KPP) and \(k-\epsilon\) (KEPS) is compared in simulating the spatio-temporal variation of mesoscale processes and eddy kinetic energy (EKE) budget terms. Model produced mean circulation from both the schemes are in good agreement with the reanalysis data, while KEPS moderately outperforming KPP in most seasons and regions. Use of KEPS mixing scheme reduces sea surface temperature (SST) and mixed layer depth (MLD) bias in all seasons in most parts of the Northwestern Indian Ocean (NWIO) as compared to KPP. This improvement in ocean properties, associated with KEPS scheme is further investigated by diagnosing the EKE budget terms, namely, shear production ( \(P\) ), buoyancy production ( \(B\) ), and dissipation ( \(\epsilon\) ). The analysis shows that \(P\) is negative along western Arabian Sea (WAS) during winter monsoon for both the cases indicative of energy transfer from small scale eddies to mean flow. On the other hand, KEPS exhibits stronger positive \(P\) compared to KPP in the southwestern part of NWIO, assisted by buoyancy production of EKE which results in higher dissipation as well. The excess EKE produced by KEPS, possibly governed by the stable water column and better representation of eddy viscosity result in improved MLD and SST in this region. Similarly, KEPS produces very strong \(P\) along WAS compared to KPP during summer monsoon and likely improves MLD and SST. Additionally, KEPS captures formation and sustenance of southern Gyre in the southwestern part of NWIO, indicating better representation of currents and eddies, while KPP fails to capture it. Our results and analysis show that KEPS performs better than KPP for modelling the mixing in NWIO, which is primarily attributed to improved representation of local energetics and vertical structure.
