The quantitative definition of the Barents Sea Atlantic Water: mapping of the annual climatic cycle and interannual variability

Abstract

Abstract The Barents Sea Atlantic Water (AW) is defined in eight different ways in the literature. These definitions can be consolidated into one statement (decision rule) that allows the separation of the AW of the Barents Sea from the rest of the water masses there. The decision rule defines AW as a straight-line function of temperature and salinity and non-Atlantic Water and Mixed Water by their proximity to AW on a temperature–salinity diagram. This rule is used to map the monthly-mean distribution of AW in the Barents Sea at 0, 30, 50 and 100 m depths. These maps demonstrate two stable seasons (winter and summer) of AW intrusion into the Barents Sea. The average duration of the AW-winter season is five months (January to May), whilst that of the AW-summer season is four months (July to October). During the winter, the area coverage of the AW at the surface equals 23% and varies slightly with depth. During summer, there is zero areal coverage of the AW at the surface, and with depth it varies considerably. The decision rule was used to map the monthly distribution of AW along latitude 74°30′N in the Barents Sea for the period 1975–1989. The maximum inflow of AW into the Barents Sea along 74°30′N occurs during March. The minimum inflow of AW occurs in August. The March/August inflow ratio is 1.55.