Mesoscale eddies are known to transport heat and biogeochemical properties from Arctic Ocean boundary currents to basin interiors. Previous hydrographic surveys and model results suggest that eddy formation may be common in the Atlantic Water (AW) inflow area north of Svalbard, but no quantitative eddy survey has yet been done for the region. Here vorticity and water property signatures are used to identify and track AW eddies in an eddy‐resolving sea ice‐ocean model. The boundary current sheds AW eddies along most of the length of the continental slope considered, from the western Yermak Plateau to 40°E, though eddies forming east of 20°E are likely more important for slope‐to‐basin transport. Eddy formation seasonality reflects seasonal stability properties of the boundary current in the eastern portion of the study domain, but on and immediately east of the Yermak Plateau enhanced eddy formation during summer merits further investigation. AW eddies tend to be anticyclonic, have radii close to the local deformation radius, and be centered in the halocline. They transport roughly 0.16 Sv of AW and, due to their warm cores, 1.0 TW away from the boundary current. These findings suggest eddies may be important for halocline ventilation in the Eurasian Basin, as has been shown for Pacific Water eddies in the Canadian Basin.

The Yermak Plateau is a topographic obstacle which warm water in the West Spitsbergen Current (Atlantic Water) must pass in order to enter the Arctic Ocean. The main route for Atlantic Water to cross the Yermak Plateau is the Yermak Pass Branch, a winter-intensified pathway characterized by pulse-like high-transport events. Here we use an eddy-resolving sea ice and ocean model to investigate oceanographic conditions that promote flow over the Yermak Plateau. Yermak Pass Branch pulses were associated with a warmer, faster West Spitsbergen Current; these conditions created a region of high offshore Ertel potential vorticity upstream of the plateau. As potential vorticity was low in the current itself, this region of high offshore potential vorticity acted as a barrier that guided flow onto the plateau. During times of enhanced recirculation in Fram Strait, this offshore potential vorticity barrier was weaker, likely allowing the current to deflect away from the continental slope. Through this potential vorticity mechanism, the upstream hydrography of the West Spitsbergen Current can determine how much Atlantic Water crosses the plateau, implying that less dense West Spitsbergen Current core water promotes more inflow into the Arctic Ocean and less recirculation in Fram Strait. Plain Language SummaryWe used an ocean and sea ice model to study a current (the West Spitsbergen Current) which carries relatively warm water to the Arctic Ocean. In a key gateway region called Fram Strait, just before the current enters the Arctic Ocean, some of the water takes a shortcut and returns south along Greenland. The rest flows over a shallower area called the Yermak Plateau. Our goal was to learn what pushed pulses of wintertime flow through one pathway or the other. We found that flow was routed into the Arctic Ocean when the current was warmer and faster. This is because the current must conserve a quantity called potential vorticity, and when the current was warmer and faster, the potential vorticity alongside the current increased. This potential vorticity "wall" guided the flow to enter the Arctic Ocean. This means that if the temperature of the current flowing toward the Arctic Ocean increases, the amount of warm water that actually enters the Arctic Ocean could also increase. CREWS ET AL.

Abstract. Fram Strait, the deepest gateway to the Arctic Ocean, is strongly influenced by eddy dynamics. Here we analyse the output from two eddy-resolving models (ROMS – Regional Ocean Modeling System; FESOM – Finite-Element Sea-ice Ocean Model) with around 1 km mesh resolution in Fram Strait, with a focus on their representation of eddy properties and dynamics. A comparison with mooring observations shows that both models reasonably simulate hydrography and eddy kinetic energy. Despite differences in model formulation, they show relatively similar eddy properties. The eddies have a mean radius of 4.9 and 5.6 km in ROMS and FESOM, respectively, with slightly more cyclones (ROMS: 54 %, FESOM: 55 %) than anticyclones. The mean lifetime of detected eddies is relatively short in both simulations (ROMS: 10 d, FESOM: 11 d), and the mean travel distance is 35 km in both models. More anticyclones are trapped in deep depressions or move toward deep locations. The two models show comparable spatial patterns of baroclinic and barotropic instability. ROMS has relatively stronger eddy intensity and baroclinic instability, possibly due to its smaller grid size, while FESOM has stronger eddy kinetic energy in the West Spitsbergen Current. Overall, the relatively good agreement between the two models strengthens our confidence in their ability to realistically represent the Fram Strait ocean dynamics and also highlights the need for very high mesh resolution.