Barotropic Trends Through the Barents Sea Opening for the Period 1975–2021

We analyze the output of a regional ocean model that comprises the North Atlantic and the Arctic Ocean for the period 1975–2021. We focus on the flow through the cross sections closing the Nordic Sea basin. The simulated flow at Barents Sea Opening (BSO) shows a clear positive trend. To understand the origin of this trend, we reconstruct the BSO flow based on wind time series over the Nordic Seas using deep learning. To explore potential links between the results from this reconstruction and the major atmospheric modes, we perform a suite of idealized experiments where the ocean model is forced with wind field anomalies that refer to known changes in the leading modes of atmospheric circulation over the North Atlantic and Arctic Oceans. Known changes in the major atmospheric wind patterns over the North Atlantic have a weak impact on the simulated BSO flow, and the sign is not consistent with the overall trend of the full simulation. The latter holds as well for the known temporal changes in the intensity of the Arctic dipole mode. The weak temporal changes in the Arctic oscillation are consistent with the trend in the BSO flow but could not explain its amplitude. Ultimately, we could not establish a clear link between the BSO flow trend and changes in the major atmospheric modes. We conclude that the atmospheric pattern responsible for the BSO flow trend does not project directly on the leading modes of atmospheric variability over the North Atlantic and the Arctic.