Stability at M₂ critical latitude in the Barents Sea

The Barents Sea is the site for one of the largest biomass productions in the world oceans. This is mainly due to the combined effect of winter thermohaline convection and a strong seasonal pycnocline during spring and summer. Secondary bloomings are due to wind‐induced entrainment of nutrients to the upper layer, which may be especially effective near 74.5°N, the critical latitude for the M 2 constituent. At this latitude, the inertial frequency equals the M 2 frequency, resulting in a strongly depth‐dependent tidal current and a thick benthic boundary layer. Our investigations of current meter measurements in the Barents Sea confirm these theoretical predictions. Statistical treatment of about 800 conductivity‐temperature‐depth stations between 70°N and 79°N reveals a stability minimum in the central part of the Barents Sea. This may be due to enhanced tidal mixing near the critical latitude. Observations of nutrients partly support this conclusion.