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The Norwegian Coastal Current

The Norwegian Coastal Current (NCC) originates in the eastern Skagerrak and follows the Norwegian coast all the way to the Barents Sea. The coastal water masses are less saline than offshore waters due to extensive outflow of brackish water from the Baltic Sea and river runoff from the Swedish and Norwegian coast. Typical current speed within the NCC is 20-50 cm/s, but velocities above 100 cm/s may occur.

Freshwater discharge from rivers, tides, winds, inflow of Atlantic water and bottom topography force the behavior within and properties of the NCC. Brackish water outflow from the Baltic Sea and freshwater discharges from rivers along the coast are mixed with both North Sea and Atlantic waters. The resulting low saline coastal current follows the Norwegian coast northward all the way to the Barents Sea. The salinity within the NCC increases gradually northwards due to entrainment of Atlantic waters. The NCC is mainly driven by density gradients, mainly due to the salinity differences, but a considerable part of the current speed within the NCC is also driven by the gradients in sea level. The main branch of Atlantic water inflow follows the southern slope of the Norwegian Trench north of Jutland (Denmark), enters eastern Skagerrak and returns westward along the Norwegian coast below the NCC. On its way through the Skagerrak, the salinity within the Atlantic water masses is reduced due to entrainment of less saline water masses.

Schematic map of the main current systems along the Norwegian coast. The NCC is show with green arrows, while the red arrows denote Atlantic water.

The freshwater input to the NCC can be separated into three sources; the Baltic Sea (50%), Norwegian rivers (40%) and runoff from rivers in the southern North Sea, in particular the German Bight. The variability of the outflow of brackish water from the Baltic Sea through the Kattegat Sea is the main contributor for seasonal variations in surface salinity off the Norwegian coast in the Skagerrak. The NCC in the Skagerrak does not act as a constant flow westwards, but alters between blocking and outflowing regimes. Dominating winds in the area controls this process. Winds from the west and southwest will typically retain some of the NCC transport and establish a frontal zone across the Skagerrak. Winds from the east will force an outflow of the NCC and may introduce higher current speeds. If such a Skagerrak outflow event occurs subsequent to a stagnating period, the velocities within the NCC will be at their maximum.


Fixed hydrographic stations

Measurements of temperature and salinity at 8 fixed hydrographic stations distributed along the Norwegian coast. The observations are taken 1-2 times per month.