Northward cooling and freshening of the warm core of the West Spitsbergen Current

Abstract

To predict future changes in the WSC heat transport, understanding of the physics of both the WSC volume transport and its heat content is essential. This paper focuses on the latter, namely, on quantifying the long-term northward cooling and freshening. We know that on its way toward the Arctic the WSC loses heat, and that one part of this cooling is due to heat loss directly into the atmosphere. Some heat could also be lost to melting of sea ice, while another part of the heat in the WSC is lost due to mixing with colder surrounding waters (by the term "mixing" we assume that the total water volume is conserved) and due to westward recirculation into the Greenland Sea. However, it is not well known what processes, circumstances and external factors are responsible Fig 1: (a) Two pathways to the Arctic Ocean, the West Spitsbergen Current (WSC) and the Barents Sea branch (BSB). (b, opposite page) Schematic illustration of the current patterns in the sea west of Svalbard, based on Johannessen (1986), Loeng (1991) and Gascard et al. (1995). Grey arrows denote warm currents of Atlantic origin and black arrows colder currents of Arctic origin. Dashed line denotes the Arctic Front west of Spitsbergen. (From Saloranta & Svendsen 2001.) (c, opposite page) Schematic cross-section across the continental slope showing the warm and saline WSC on the slope and the cooler and fresher waters on the shelf. Dashed lines denote our upper-slope domain with which we approximate the warm core of the WSC. The arrow denotes the direction to which temperature, current speed and topographic current steering in the WSC increase. The illustration is based on Hanzlick (1983); Jónsson et al.