Mechanism of a Positive Feedback in Long-Term Variations of the Convergence of Oceanic and Atmospheric Heat Fluxes and of the Ice Cover in the Barents Sea

Resumo

This paper presents the results of a study of the interannual variability of the convergence of oceanic and atmospheric advective heat fluxes in the Barents Sea region for 1993–2014 using combined (in situ, satellite, and model-based) datasets: ARMOR-3D and ERA-Interim. The convergence of oceanic and atmospheric heat fluxes play a leading role in variations of the area of ice cover of the Barents Sea on interdecadal and interannual time scales, respectively. The interdecadal and the interannual variations of the oceanic heat flux are mainly shaped by current velocity variations in the western boundary of the Barents Sea. The contribution of current velocity to interdecadal variations is 70% of the increase in the oceanic heat flux, mainly due to an increased transport in the North Cape Current. The variations in the transport of the North Cape and of the Return currents has been found to be associated with the variation in the meridional gradient of the zonal wind speed, which, in turn, is caused by an increased oceanic heat transport into the Barents Sea and by the resulting melting of the sea ice. The in situ observations confirm the possible efficiency of the positive feedback between variations in the oceanic heat flux into the Barents Sea, the area of the ice cover, and of the character of atmospheric circulation in the Barents Sea region on decadal time scales.