Greenland Sea - Hydrology, Climate and Ice

Hydrology, Climate and Ice

The climate is Arctic and varies significantly across the vast sea area. Air temperatures fluctuate between –49 °C (–57 °F), near Spitsbergen in winter, and 25 °C (77 °F) off Greenland in summer. Averages are –10 °C (14 °F) in the south and –26 °C (–15 °F) in the north in February, which is the coldest month. The corresponding values for the warmest month, August, are 5 °C (41 °F) in the south and 0 °C (32 °F) in the north. The summer is very short, as the number of days per year when the temperature rises above 0 °C varies between 225 on the south to 334 in the north. The annual precipitation is 250 mm (10 in) in the north, but is twice higher in the south.

Northern winds continue through the whole year, cooling the surface water and bringing ice to the south. The average surface water temperature is about –1 °С (30 °F) or lower in the north and 1–2 °C in the south; the corresponding summer temperatures are about 0 °C and 6 °C (43 °F). The bottom water temperatures are below –1 °С. The surface water salinity is 33.0–34.5 parts per thousand (‰) in the eastern and below 32.0‰ in the western parts, increasing to 34.9‰ toward the bottom. The water color is green. Tides are semi-diurnal with the average height of 4.4 m. Together with the water currents, they break up the floating ice sheets and mix various water layers both laterally and along the depth.

The progressively colder waters of North Atlantic Current sink in the Arctic Ocean, returning south in the form of cold East Greenland Current, an important part of the Atlantic conveyor belt, which flows along the western part of the sea. Along the eastern part flows the warm Spitsbergen Current, a part of Gulf Stream. Mixtures of cold, fresh water ice melt and the warm, salty Spitsbergen Current may experience cabbeling, and might contribute to thermohaline circulation. The combination of those currents creates a counter-clockwise water flow in the central part of the sea.

Because of frequent fogs and winds and currents, which continuously transport ice and icebergs through the Greenland Sea to the south, the Greenland Sea has a narrow window for commercial navigation - the ice season starts in October and ends in August. Three types of floating ice are distinguished: Arctic pack ice (several meters thick), sea ice (about a meter thick) and freshwater icebergs.