Nordic Seas

Several water masses are found interacting in the Nordic Sea. These water masses are present due to subduction, deep convective mixing, surface/frontal mixing, and entrainment of water from low and high latitudes. Interaction from multiple water sources can lead to varying conditions. New primary production is higher in this region, usually exceeding regenerated primary production. New production is higher in regions where water interacts with Atlantic Water, which has nutrient-rich waters. When looking at carbon flux from the atmosphere to the ocean, this region is considered one of the highest in the world's oceans. This region is also known as being one of the few bodies of water that take up large quantities of carbon dioxide yearly, ranging from 20 to 85 g C m⁻²y⁻¹, which is considered high in comparison the carbon dioxide flux in the world's oceans.

The Nordic Seas include the Greenland Sea, the Norwegian Sea, and the Iceland Sea. The Greenland and the Norwegian Sea are separately distinguished by Mohn's Ridge. The Greenland and Iceland Sea are separated by the Jan Mayen fracture zone, and the Norwegian and Iceland Seas have the Aegir Ridge between them. The Nordic Seas have varying and diverse features as a result of each sea having separate water mass structures and circulation patterns. The Greenland Sea produces dense waters because of its high salinity and cooler temperatures from winter cooling. Higher salinity is present as a result of the Greenland Sea's close proximity to the salinity inflow that occurs from the Atlantic Ocean. Another dense water source comes from the Arctic waters that also flow into the Greenland Sea. These water source mixtures are important because they play a role in the overflows that occur in the North Atlantic. The water that overflows from the Greenland ridge becomes the North Atlantic Deep Water dense water, even though this body of water does not make up the deep waters of the Nordic Sea.

Circulation

The circulation of the Nordic Seas is cyclonic.

The Nordic Seas exchange water with the North Atlantic in the upper ocean. Warm water from the North Atlantic enters the Nordic Seas from the east, specifically in the Norwegian Atlantic Current (part of the North Atlantic Current). The western boundary of the Nordic Seas is the southward-flowing East Greenland Current. This current enters through the Fram Straight from the Arctic. This current is considered one of the main ways for Arctic sea ice to be exported. The East Greenland Current splits into the Jan Mayen Current on the eastern boundary of the Nordic Seas due to bathymetry. The Jan Mayen Current plays an important role in the dense water formation that occurs in the Greenland Sea. Continuing northward, the Norwegian Atlantic Current flows along the coast of Norway to the Arctic, eventually separating into the Barents Sea and the Spitsbergen Current. There are several gyre circulations that occur in the Nordic Seas. The subsurface waters leave the Nordic Seas through the south from overflows between Greenland and Scotland. The intermediate water leaves through the Denmark Straight and the Iceland Ridge. The densest overflow waters leave through the Faroe-Bank Channel.