Return of deep shelf/slope convection in the western Barents Sea?

Shelf/slope convection at and from the Arctic shelf seas constitutes part of the thermohaline overturning in the North Atlantic. It is driven by densification of surface waters through their enrichment with brine due to persistent freezing. This process is very efficient in off-shore shelf polynyas and may lead to high densities in areas with high initial salinity like the Barents Sea. High bottom water salinities were measured in Storfjorden occasionally in the 1980s but salinities were lower in the 1990s when the water - despite being at the freezing point - was not dense enough to sink below the Atlantic layer where it acted as fresh water source. Recently, bottom water salinities in the Storfjorden were high again and brine-enriched shelf water ventilated the Norwegian Sea through a saline plume extending in summer 2002 down to 2500 m depth. The Polarstern cruise WARPS (Winter ARctic Polynya Study), taking place in winter 2003, will enable us to study dense water formation in Storfjorden and slope convection right in time in a phase of returning deep ventilation. Results from this study will be presented.