The Yermak Pass Branch: A Major Pathway for the Atlantic Water North of Svalbard?

An upward‐looking Acoustic Doppler Current Profiler deployed from July 2007 to September 2008 in the Yermak Pass, north of Svalbard, gathered velocity data from 570 m up to 90 m at a location covered by sea ice 10 months out of 12. Barotropic diurnal and semidiurnal tides are the dominant signals in the velocity (more than 70% of the velocity variance). In winter, baroclinic eddies at periods between 5 and 15 days and pulses of 1–2 month periodicity are observed in the Atlantic Water layer and are associated with a shoaling of the pycnocline. Mercator‐Ocean global operational model with daily and 1/12° spatial resolution is shown to have skills in representing low‐frequency velocity variations (>1 month) in the West Spitsbergen Current and in the Yermak Pass. Model outputs suggest that the Yermak Pass Branch has had a robust winter pattern over the last 10 years, carrying on average 31% of the Atlantic Water volume transport of the West Spitsbergen Current (36% in autumn/winter). However, those figures have to be considered with caution as the model neither simulates tides nor fully resolves eddies and ignores residual mean currents that could be significant.