THE BARENTS SEA POLAR FRONT IN SUMMER

In August 1992 a combined physical oceanography and acoustic tomograph y experiment was conducted to describe the Barents Sea Polar Front (BS PF) and investigate its impact on the regional oceanography. The study area was an 80 x 70 km grid east of Bear Island where the front exhib its topographic trapping along the northern slope of the Bear Island T rough. Conductivity-temperature-depth, current meter, and acoustic Dop pler current profiler (ADCP) data, combined with tomographic cross sec tions, presented a highly resolved picture of the front in August, All hydrographic measurements were dominated by tidal signals, with the s trongest signatures associated with the M2 and S2 semidiurnal species, Mean currents in the warm saline water to the south of the front, der ived from a current meter mooring and ADCP data, were directed to the southwest and may be associated with a barotropic. recirculation of No rwegian Atlantic Water (NAW) within the Bear Island Trough. The geostr ophic component of the velocity was well correlated with the measured southwestward mean surface layer flow north of the front, The frontal structure was retrograde, as the frontal isopleths sloped opposite to the bathymetry. The surface signature of the front was dominated by sa linity gradients associated with the confluence of Atlantic and Arctic water masses, both warmed by insolation to a depth of about 20 m. The surface manifestation of the front varied laterally on the order of 1 0 km associated with tidal oscillations, Below the mixed layer, temper ature and salinity variations were compensating, defining a nearly bar otropic front. The horizontal scale of the front in this region was si milar to 3 km or less, At middepth beneath the frontal interface, tomo graphic cross sections indicated a high-frequency (similar to 16 cpd) upslope motion of filaments of NAW origin. The summertime BSPF was con firmed to have many of the general characteristics of a shelf-slope fr ontal system [Mooers et al., 1978] as well as a topographic-circulator y front [Federov, 1983].