On the Barents Sea Polar Front in summer and interpretations of the associated regional oceanography using an Arctic Ocean general circulation model

Abstract

In August 1992 a combined physical oceanography and acoustic tomography experiment was conducted to describe the Barents Sea Polar Front (BSPF) and investigate its associated mesoscale phenomena. The study area was an 80 by 70 km grid east of Bear Island where the front exhibits topographic trapping along the northern slope of the Bear Island Trough. CTD, current meter and CP data, combined with tomographic cross-sections, presented a highly resolved picture of the front in August. All hydrographic measurements were dominated by tidal signals with the strongest signatures associated with the M2 and S2 semidiurnal species. Tomographic cross sections indicated a high-frequency (approx 16 cpd) upslope motion of filaments of Norwegian Atlantic Water (NAW) origin at the front. Mean currents in the warm saline water to the south of the front, derived from a current meter mooring and CP data, were directed to the southwest and are associated with a barotropic recirculation of NAW within the Bear Island Trough. To examine the relation of BSPF to the regional oceanography, a high resolution (1/60 and 30 vertical levels) Arctic Ocean and Nordic Seas model was developed from the Semmer-Cherrin General Circulation Model (GCM) with a free-surface. Three numerical experiments, annual mean forcing, annual mean forcing coupled with semidiurnal tidal forcing, and seasonal forcing, were conducted to simulate conditions in 1992. All three numerical experiments predicted the recirculation of NAW within Bear Island Trough supporting the observed conditions. The unique experiment with simulated tides indicated enhanced mixing on the slopes and shallow topography of the Barents Sea.