Comparison of ocean vertical mixing schemes in the Max Planck Institute Earth System Model (MPI-ESM1.2)

Abstract. For the first time, we compare effects of four different ocean vertical mixing schemes on mean state and atmosphere in Max Planck Institute Earth System Model (MPI-ESM1.2). These are namely default Pacanowski Philander (1981) (PP) scheme, K-profile parameterization (KPP) from Community Vertical Mixing (CVMix) library, a recently implemented scheme based turbulent kinetic energy (TKE), developed prognostic for internal wave dissipation, energy, (IDEMIX) to replace often assumed constant background diffusivity interior. In this study, IDEMIX is combined with TKE (collectively called TKE+IDEMIX scheme) provide an energetically more consistent framework mixing, as it does not rely unwanted effect creating spurious mixing. Energetic consistency can have implications climate. Therefore, focus climate them three that commonly used other models but consistent. We find warmer sea surface temperatures (SSTs) North Atlantic Nordic Seas using KPP or TKE(+IDEMIX), which related 10 % higher overflows cause stronger deeper upper cell meridional overturning circulation (AMOC) thereby enhanced northward heat transport inflow warm saline water Indian Ocean into South Atlantic. Saltier subpolar lead increased deep convection thus overflows. Due SSTs, extratropics Northern Hemisphere become weakening gradient jet stream. With KPP, tropics Southern also without Using (TKE+IDEMIX) produces heterogeneous realistic pattern eddy diffusivity, lower diffusivities flat-bottom basins elevated turbulence over rough topography. improves particular Arctic reduces bias Water layer. conclude although shortcomings due model resolution determine global-scale pattern, choice may play important role regional biases.