Australia: The Land Where Time Began

A biography of the Australian continent 

Artic Ocean

The authors1 describe the Arctic Ocean as a Mediterranean Sea surrounded by 3 continents, North America, Europe and Asia, with connecting to the Atlantic Ocean on both sides of Greenland and to the Pacific by the Bering Strait. South of Svalbard and north of Iceland is the region known as the Nordic Seas. Some of the densest water of the global ocean is produced in this region making it a central region for the transformation and production of deep water. It is also a high latitude connection between the fresher water of the North pacific and the saltier water of the North Atlantic. The high albedo (high reflectivity) of the sea ice of the Arctic Ocean is a vital part of the climate of the world, that is sensitive to changes of climate. The authors¹ say that since the 1990s there is a large and growing body of information about the ice cover, circulation and water masses in the Arctic Ocean as a result of important climate changes, and the initiation of difficult hydrographic series in this region.

The Arctic Basin is comprised of 2 basins, the Canadian Basin, with a depth of about 3800 m, and the Eurasian Basin, with a depth of about 4200 m. The Lomonosov Ridge, extending from Greenland to Siberia past the North Pole, with a maximum sill depth of about 1870 m ((Björk et al., 2007). The Eurasian basin is comprised of the Nansen Basin and the Amundsen Basin. The Canadian Basin is subdivided into the Makarov Basin and the Canada Basin. The Arctic margin to the north of Eurasia and the cost of Alaska are characterised by wide continental shelves that range from 50-100 m in depth, totaling about 53 % of the Arctic Ocean, north of Fram Strait, though it contains less than 2 % of the water volume (Jakobsson, 2002). 

The connection of the Arctic Ocean with the other oceans to the Nordic Seas is the deepest through Fram Strait between Greenland and Spitsbergen where the sill depth is 2,600 m. To the north and east of Svalbard the sill that separates it from Franz Joseph Land and Novaya Zelmya is about 200 m deep (Coachman & Aagaard, 1974). Where the Arctic Ocean is connected to the Bering Sea and the Pacific Ocean, the Bering Strait, the passage is narrow and the sill is 45 m deep. The transport of the Pacific water, especially its freshwater content, to the Arctic ocean is significant, on the order of 1 Sv (Sverdrup, a measure of volume transport). There are also several channels through the Canadian Archipelago that connect the Arctic Ocean tothe North Atlantic Ocean, mainly Nares Strait, with a sill depth of 250 m, and Lancaster Sound, with a sill depth of 130 m), leading to Baffin bay and on to the Atlantic Ocean.

The Greenland Sea, Norwegian Sea and the Iceland Sea are all included in the Nordic Seas situated between Fram Strait and the Greenland-Scotland Ridge. These oceanographic names that are commonly used are linked loosely to the formal topographic names (e.g., Perry, 1986).  There are 3 main sections that comprise the Greenland-Scotland Ridge (Hansen & Østerhus, 2000):

• Denmark Strait, Greenland-Iceland, sill depth 620 m.
• Iceland-Faroe Ridge, sill depth 480 m.
• Faroe-Shetland Ridge, sill depth 840 m, in the Faroe Bank Channel.

The Mohns Ridge in the Nordic Seas separates the Greenland Sea from the Norwegian Sea, and by the Jan Mayen fracture Zone from the Iceland Sea. The Aegir Ridge separates the Norwegian Sea from the Iceland Sea. The circulation and structure of the water mass of each of these seas is to some extent separate. Baffin Bay and Davis Strait to the west of Greenland connects the Arctic Ocean to the Atlantic Ocean through, or past, Hudson Bay.

The surface circulation of Arctic Ocean is comprised of mainly cyclonic circulation in the Nordic Seas and Eurasian Basin, and in the Canadian Basin, mainly anticyclonic circulation (Beaufort Gyre). The major cross-polar circulation connecting these 2 systems is the Transpolar Drift (TPD). In the Nordic Seas open ocean convection and shelf brine rejection in the Artic Ocean cause overturn, with denser outflow back into the North Atlantic Ocean.

Sources & Further reading

1. Emery, William J., Pickard, George L., Tally, Lynne D., & Swift, James H., 2011, Descriptive Physical Oceanography, an Introduction, Academic Press.

Links

Website for source 1

Oceanography