An emerging pathway of Atlantic Water to the Barents Sea through the Svalbard Archipelago: drivers and variability
Abstract. The Barents Sea, an important component of the Arctic Ocean, is experiencing shifts in ocean currents, stratification, sea-ice variability, and marine ecosystems. Inflowing Atlantic Water (AW) is known to be a key driver of change. Although AW predominantly enters the Barents Sea via the Barents Sea Opening, other pathways exist but remain relatively unexplored. Summer climatology fields of temperature in the last century compared to 2000–2019 indicate warming in the trench Storfjordrenna and the shallow banks Hopenbanken and Storfjordbanken in the Svalbard Archipelago, and shoaling of AW, extending further into the "channel" between Edgeøya and Hopen islands. This region emerges as a pathway of AW into the northwestern Barents Sea. One year-long records from a mooring deployed between September 2018 and November 2019 at a saddle in this channel, show the flow of Atlantic-origin waters into the Arctic domain of the northwestern Barents Sea. The average current is directed eastward, into the Barents Sea, but is dominated by large variability throughout the year. Here, we investigate this variability on time scales from hours to months. Wind forcing mediates the currents and the water and heat exchange through the channel through geostrophic adjustment to Ekman transport. The main drivers for the AW inflow and the cross-saddle transport of positive temperature anomalies are persistent strong semidiurnal tidal currents, intermittent wind-forced events, and wintertime warm water intrusions forced by upstream conditions. We propose that similar topographic constraints where the Polar Front acts like a barrier may become more important for AW inflow and heat exchange in the future. The ongoing warming and possible shoaling of AW together with changes in the large-scale weather patterns would likely increase inflow and heat transport through the processes identified in this study.
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