Composition of cold. low salinity Barents Sea Water
The cold, low salinity water on the eastern slope of the St. Anna Trough is composed of two modes (Fig. 2): one low salinity fraction almost at the freezing point (mode A) at the upper part of the flank, and one warmer, more saline fraction (mode B) in the central deep part of the trough.
Both modes are also found in the central Barents Sea. The warm inflow from the Norwegian Sea, with low salinities of the coastal current and higher salinities of Atlantic Water, already has lost its distinct signal northwest of Novaya Zemlya. During summer, very cold water (mode A) is found on shallow banks or the slope off NovayaZemlya, where part of the cold water, formed in winter, remains topographically trapped in a Taylor-column circulation. However, the time series further eastwards (J2, Fig. 3) show that the upper 100 m of the eastward flowing water undergoes a seasonal cycle, with moderately warm water in summer and convected water close to the freezing point (mode A) in winter. The cooling of the upper layer in winter is always associated with a drop in salinity (not shown here) indicating the downward mixing of low salinity surface water. On the other hand, the temperature of the deepest layers shows no seasonal signal at all and remains at about -0.5℃ (mode B) throughout the year.
Hence, considerable transformation of cold shelf water must take place already within the Barents Sea. The generation and downstream change of a shelf water plume was studied using time series obtained south of the Storfjord in the Svalbard Archipelago between 1991 and 1994 (Fig. l). Cold bottom water with temperatures close to the freezing point drained from Storfjord continuously from March until September. About one month after the plume front had left the Storfjord, it reached the shelf break at a distance of 150 km with considerably increased temperatures and salinities. The plume had spread laterally, but its thickness of about 40 m remained almost constant. The change of volume transport and of the temperature/salinity properties indicate entrainment of an equal amount of Atlantic water into the plume between the production area and the shelf edge (Fig. 4). As a result, the
