Abstract. Arctic Ocean simulations in 19 global ocean-sea ice models participating in the Ocean Model Intercomparison Project (OMIP) of the CMIP6 are evaluated in this paper. Our results indicate that no significant improvements were achieved in the Arctic Ocean simulations from the previous Coordinated Ocean-ice Reference Experiments phase II (CORE-II) to the current OMIP. Large model biases and inter-model spread exist in the simulated mean state of the halocline and Atlantic Water layer in the OMIP models. Most of the OMIP models suffer from too thick and deep Atlantic Water layer, too deep halocline base, and large fresh biases in the halocline. The OMIP models largely agree on the inter-annual and decadal variability of the Arctic Ocean freshwater content and volume/heat/freshwater transports through the Arctic Ocean gateways. The models can reproduce observed changes in volume, heat and freshwater transports through the gateways except for the Bering Strait. Overall, the performance of the Arctic Ocean simulations is similar between the CORE2-forced OMIP-1 and JRA55-do-forced OMIP-2.

Abstract. Model resolution and the included physical processes are two of the most important factors that determine the realism of the ocean model simulations. In this study, a new global surface wave-tide-circulation coupled ocean model FIO- COM32 with resolution of 1/32° × 1/32° is developed and validated. Promotion of the horizontal resolution from 1/10° to 1/32° leads to significant improvements of the simulations of surface eddy kinetic energy (EKE), fine structures of sub- mesoscale to mesoscale movements and the accuracy of simulated global tide. The non-breaking surface wave-induced mixing (Bv) is proved to be an important contributor that improves the agreement of the simulated summer mixed layer depth (MLD) of the model and the Argo observations even with high horizontal resolution of 1/32°, the mean error of the simulated mid-latitude summer MLD is reduced from -4.8 m in numerical experiment without Bv to -0.6 m in experiment with Bv. With the global tide is included, the global distributions of internal tide can be explicitly simulated in this new model and is comparable to the satellite observations. Comparisons using Jason3 along-track sea surface height (SSH) wave-number spectral slopes of mesoscale ranges show that internal tide induced SSH undulations is a key factor contributing to the substantially improved agreement of model and satellite observations in the low latitude and low EKE regions. For ocean model community, surface wave, tidal current and ocean circulation have been separating into different streams for more than half century. It should be the time to merge these streams for new generation ocean model development.