The role of Arctic gateways on sea ice and circulation in the Arctic and North Atlantic Oceans: a sensitivity study with an ocean-sea-ice model

Abstract

The impact of changes in volume, heat and freshwater fluxes through Arctic gateways on sea ice, circulation and fresh water and heat contents of the Arctic and North Atlantic Oceans is not fully understood. To explore the role played by each gateway, we use a regional sea-ice ocean general circulation model with a fixed atmospheric forcing. We run sensitivity simulations with combinations of Bering Strait (BS) and Canadian Arctic Archipelago (CAA) open and closed inspired by paleogeography of the Arctic. We show that fluxes through BS influence the Arctic, Atlantic and Nordic Seas while the impact of the CAA is more dominant in the Nordic Seas. In the experiments with BS closed, there is a change in the surface circulation of the Arctic with a weakening of the Beaufort Gyre by about thirty percent. As a consequence, the Siberian river discharge is spread offshore to the west, rather than being directly advected away by the Transpolar Drift. This results in a decrease of salinity in the upper 50 m across much of the central Arctic and East Siberian and Chukchi Seas. We also find an increase in stratification between the surface and subsurface layers after closure of BS. Moreover, closure of the BS results in an upward shift of the relatively warm waters lying between 50 and 120 m, as well as a reorganization of heat storage and transport. Consequently, more heat is kept in the upper layers of the Arctic Ocean, thus increasing the heat content in the upper 50 m and leading to a thinner sea ice cover. The CAA closing has a large impact on sea ice, temperature and salinity in the subarctic North Atlantic with opposite responses in the Greenland-Iceland-Norwegian Seas and Baffin Bay. It is also found that CAA being open or closed strongly controls the sea ice export through the Fram Strait. In all our experiments, the changes in temperature and salinity of the Barents and Kara Seas, and in fluxes through Barents Sea Opening are relatively small, suggesting that they are likely controlled by the atmospheric processes. Our results demonstrate the need to take into consideration the fluxes through the Arctic gateways when addressing the ocean and climate changes during deglaciations as well as for predictions of future climate.

A Synthesis of the Upper Arctic Ocean Circulation During 2000–2019: Understanding the Roles of Wind Forcing and Sea Ice Decline

“…Changes in ocean inflow from the North Pacific and North Atlantic could also influence the upper ocean circulation in the Arctic Ocean (Spall, 2020;Karami et al, 2021;Wang et al, 2021b). For example, stronger Pacific Water inflow through the Bering Strait can increase the sea surface height along the continental slope of the Canada Basin so that the ocean circulation towards the Canadian Arctic Archipelago and Fram Strait is strengthened (Spall, 2020;Wang et al, 2021b).…”

The role of upper-ocean heat content in the regional variability of Arctic sea ice at sub-seasonal timescales

“…For instance, changes in the strength of stratification and halocline stability, which this study did not address, remain a large source of uncertainty due to substantial regional variability and model spread (e.g., Muilwijk et al, 2022;Pan et al, 2023;Shu et al, 2022). Several physical mechanisms can influence the exchange of heat fluxes between the ocean, atmosphere, and sea ice, including changes in wind forcing (Onarheim et al, 2015;Lien et al, 2017) and freshwater fluxes (Karami et al, 2021). For instance, there is evidence that wind-driven mixing will increase under icedepleted conditions (Perovich, 2011), which in turn will accelerate sea ice loss (Liang and Losch, 2018).…”

The importance of Canadian Arctic Archipelago gateways for glacial expansion in Scandinavia

“…Consequently, a comparatively small reduction in salinity from freshwater input can weaken convective overturning, even in the case of surface cooling 34 ; by contrast, an increase in high-latitude salinity can have the opposite effect and strengthen convective overturning. However, as previous studies have shown [35][36][37] , both the AMOC strength and the North Atlantic climate are potentially sensitive to the status of the ocean gateways in the Arctic. At present, the North Pacific is less saline and has a relatively higher sea surface height than the Arctic Ocean.…”