The oceanic heat transported northward from the North Atlantic is one of the key factors in the surface energy budget of the Arctic Ocean. Its loss due to exchanges with the atmosphere along the way and sea ice melt downstream might impact not only the regional but possibly the hemispheric atmospheric circulation. The magnitude and variability of northward oceanic heat transport control the surface winter-time turbulent fluxes over the sub-Arctic marginal seas as well as alters the sea ice regime in the central Arctic. Out of the two northward pathways of warm water into the eastern Arctic, the one across the Barents Sea is of higher importance not only to the sea ice conditions downstream but also because of large amounts of heat exchanged with the atmosphere above. Unfortunately, the actual amounts of oceanic heat delivered into the Barents Sea and downstream into the eastern Arctic are inadequately constrained by observations and highly varying in global ocean and climate models.

Here we present results from regional and global climate models to examine the relative importance of the oceanic heat transport, its convergence in the Barents Sea and into the central Arctic Ocean on the state of sea ice and the role of ocean in Arctic Amplification (AA). We use a subset of models participating in the Phase 6 of Coupled Model Intercomparison Project (CMIP6), including contributions to the High Resolution Model Intercomparison Project (HighResMIP), and the Regional Arctic System Model (RASM) to evaluate the sensitivity of oceanic fluxes to model resolution, compare those to the limited observational data, and asses their relative impact on AA. The findings of this study are offered as a guidance for future improvements critical to the representation and projections of Arctic climate change and AA as well as for the observational requirements.