An emerging pathway of Atlantic Water to the Barents Sea through the Svalbard Archipelago: drivers and variability

Abstract

Abstract. The Barents Sea, an important component of the Arctic Ocean, is experiencing changes in its ocean currents, stratification, sea ice variability, and marine ecosystems. Inflowing Atlantic Water (AW) is a key driver of these changes. As AW predominantly enters the Barents Sea via the Barents Sea Opening, other pathways remain relatively unexplored. Comparisons of summer climatology fields of temperature from the last century with those from 2000–2019 indicate warming in the Storfjordrenna trough and along two shallow banks, Hopenbanken and Storfjordbanken, within the Svalbard Archipelago. Additionally, they indicate shoaling of AW that extends further into the “channel” between the islands of Edgeøya and Hopen. This region emerges as a pathway enabling AW to enter the northwestern Barents Sea. Moreover, 1-year-long records from a mooring deployed between September 2018 and November 2019 at the saddle of this channel show the flow of Atlantic-origin waters into the Arctic domain of the northwestern Barents Sea. The average current is directed eastwards into the Barents Sea and exhibits significant variability throughout the year. Here, we investigate this variability on timescales ranging from hours to months. Wind forcing mediates currents, water exchange, and heat exchange through the channel by driving geostrophic adjustment to Ekman transport. The main drivers of the warm-water inflow and across-saddle transport of positive temperature anomalies include persistently strong semidiurnal tidal currents, intermittent wind-forced events, and wintertime warm-water intrusions forced by upstream conditions. We propose that similar topographic constraints near AW pathways may become more important in the future. Ongoing warming and shoaling of AW, coupled with changes in large-scale weather patterns, are likely to increase warm-water inflow and heat transport through the processes identified in this study.