Editing Norwegian Sea (section)

=== Surface currents ===
The hydrology of the upper water layers is largely determined by the flow from the North Atlantic. It reaches a speed of 10 [[Sverdrup|Sv]] (1 Sv = million m<sup>3</sup>/s) and its maximum depth is 700 metres at the Lofoten Islands, but normally it is within 500 metres.<ref name=b366/> Part of it comes through the Faroe-Shetland Channel and has a comparatively high [[salinity]] of 35.3‰ (parts per thousand). This current originates in the North Atlantic Current and passes along the European continental slope; increased evaporation due to the warm European climate results in the elevated salinity. Another part passes through the Greenland-Scotland trench between the Faroe Islands and [[Iceland]]; this water has a mean salinity between 35 and 35.2‰.<ref name="Aken119">[[#refAken|Aken, 2007]], pp. 119–124</ref> The flow shows strong seasonal variations and can be twice as high in winter as in summer.<ref name="Driving"/> While at the Faroe-Shetland Channel it has a temperature of about 9.5&nbsp;°C; it cools to about 5&nbsp;°C at Svalbard and releases this energy (about 250 terawatts) to the environment.<ref name="Driving44">Roald Sætre ''Driving forces'' in: [[#refSætre|Sætre, 2007]], pp. 44–58</ref><ref name=b366/>

The current flowing from the [[North Sea]] originates in the Baltic Sea and thus collects most of the drainage from northern Europe; this contribution is however relatively small.<ref name="Driving">[[#refSætre|Sætre, 2007]], pp. 44–58</ref> The temperature and salinity of this current show strong seasonal and annual fluctuations. Long-term measurements within the top 50 metres near the coast show a maximum temperature of 11.2&nbsp;°C at the [[63rd parallel north|63° N parallel]] in September and a minimum of 3.9&nbsp;°C at the North Cape in March. The salinity varies between 34.3 and 34.6‰ and is lowest in spring owing to the inflow of melted snow from rivers.<ref name=b366/> The largest rivers discharging into the sea are [[Namsen]], [[Ranelva]] and [[Vefsna]]. They are all relatively short, but have a high discharge rate owing to their steep mountainous nature.<ref name="Sepp"/>

A portion of the warm surface water flows directly, within the [[West Spitsbergen Current]], from the Atlantic Ocean, off the Greenland Sea, to the Arctic Ocean. This current has a speed of 3–5 Sv and has a large impact on the climate.<ref name="Tyler45">[[#refTyler|Tyler, 2003]], pp. 45–49</ref> Other surface water (~1 Sv) flows along the Norwegian coast in the direction of the [[Barents Sea]]. This water may cool enough in the Norwegian Sea to submerge into the deeper layers; there it displaces water that flows back into the North Atlantic.<ref name="Tyler">[[#refTyler|Tyler, 2003]], pp. 115–116</ref>

Arctic water from the East Iceland Current is mostly found in the southwestern part of the sea, near Greenland. Its properties also show significant annual fluctuations, with long-term average temperature being below 3&nbsp;°C and salinity between 34.7 and 34.9‰.<ref name=b366/> The fraction of this water on the sea surface depends on the strength of the current, which in turn depends on the pressure difference between the [[Icelandic Low]] and [[Azores High]]: the larger the difference, the stronger the current.<ref name="ICES2">[[#refICES|ICES, 2007]], pp. 2–4</ref>