Wind-driven cross-shelf exchange-west spitsbergen current as a source of heat and salt for the adjacent shelf in arctic winters

Cross‐shelf exchange can drive substantial hydrographic changes on shelves and along slopes. In this study, time series from moorings, profiles collected by a tagged seal, atmospheric reanalysis data, and weather regimes classification were used to investigate cross‐shelf exchange at the slope‐shelf interface south‐west of Spitsbergen during the four winters 2011–2014. Assessment of Ekman transport (ET) as a driving force and linking cross‐shelf exchange to large‐scale weather patterns were in focus. Strong positive correlations were found between zonal ET and hydrographic observations on the shelf, indicating its strong impact on cross‐shelf exchange. Strong negative correlations were found between the meridional ET and temperature and salinity measured on the shelf in winter 2012, indicating a suppressing role of westerly winds on fresher and colder outflows from the Barents Sea. The ETs in a wider area near the Svalbard Archipelago show substantial variations on short‐term, interannual and long‐term time scales due to changes in large‐scale atmospheric patterns. The regional wind speed shows a significant negative trend in winters between 1992 and 2016. At the same time, cumulative winter zonal ET increased on the north‐western Spitsbergen shelf, indicating a higher overall cross‐shelf exchange along the western Spitsbergen shelf break, while meridional ET south‐west of Spitsbergen decreased, indicating a reduced outflow of fresher and colder water from the Barents Sea. For the time period between 1980 and 2016, the winter air and sea surface temperatures (sea‐ice fraction) exhibit significant positive (negative) trends which even multiplied by factor of 2–3 in winters 2004–2016