On the mechanism of a positive feedback in long-term variations of the convergence of oceanic and atmospheric heat fluxes, and the ice cover in the Barents sea

Abstract

This paper presents a study the interannual variability of the convergence oceanic and atmospheric advective heat fluxes in the Barents Sea region for 19932014, using combined in situ, satellite and numerical model-based oceanic and atmospheric data-sets: ARMOR-3D and ERA-Interim. On inter-decadal scales, the leading role of convergence of the oceanic heat flux, and on interannual scale of atmospheric heat flux are demonstrated to play the leading role in variations of the sea-ice area of the Barents Sea. The inter-decadal and the interannual variations of the oceanic heat flux are found to be mainly shaped by variations of the current velocity. In the long-term tendencies the current velocity is responsible for about 70% of the increase in the oceanic heat flux, mainly due to a higher transport in the North Cape Current. Variations in transport of the North Cape current and of the Return current are governed by variations in the meridional gradients of the zonal wind speed, in turn, caused by the stronger oceanic heat transport into the Barents sea and by the consequent melting of the sea-ice. The in situ observations supports the effectiveness of the previously suggested positive feedback between variations in the oceanic heat flux into the Barents Sea, and changes of the sea-ice area and of the atmospheric circulation in the Barents Sea region on the decadal time scales.