Influence of Atmospheric and Oceanic Model Resolution on Volume and Heat Transports through Arctic Gateways in Coupled Climate Simulations

Coupled climate simulations were performed with four different combinations of atmospheric and oceanic horizontal resolutions in our mixed-resolution experiments (OCE_LR+T63, OCE_LR+T127, OCE_HR+T63, OCE_HR+T127). We investigated the effect of horizontal grid resolution on volume and heat transports through the Arctic gateways and found that the difference in ocean resolution accounts for most of the differences in simulated present-day and future volume and heat transports through the gateways - most prominently in the Atlantic sector through the Fram Strait and at the Barents Sea entrance. In Fram Strait, with the lower ocean resolution a higher increase in net outflow is predicted for the end of the 21st century than with higher ocean resolution. This is mainly driven by a predicted decrease in inflow through Fram Strait. For the Barents Sea entrance the net inflow is predicted to increase towards the end of the first century. This predicted increase is also higher with lower resolution. At the Barents Sea entrance all simulations predict a considerable increase of heat transport into the Arctic. In accordance with the predicted higher volume transport into the Barents Sea in the lower resolution ocean, the heat transport is also significantly higher with lower ocean resolution. Between low and high atmospheric resolution, the predicted end-century heat transport into the Barents Sea is higher with higher atmospheric resolution on both ocean grids.