The smallest and most poorly studied of the oceans on earth. It covers an area of 14 million square km that is divided by three submarine ridges, i.e. the Alpha Ridge, the Lomonosov Ridge, and an extension of the mid-Atlantic ridge. It is also nearly landlocked, covered year-round by pack ice, and one-third of its area is continental shelf containing marginal seas. The marginal seas of the Arctic are the Beaufort Sea, the Chukchi Sea, the East Siberian Sea, the Laptev Sea, the Kara Sea and the Barents Sea. An important climatic function of the Arctic and its adjacent seas is the production of the dense water than drives the global transports of heat and fresh water between the high latitude North Atlantic and the Pacific.

The physical processes that combine to produce the circulation in the Arctic and its marginal seas include:

• salt rejection from sea-ice growth forming dense water that continues surface buoyancy forcing after the freezing point is reached, preferentially where offshore winds maintain open waters for prolonged periods;
• advection of ice produced in marginal seas that exports fresh water from the basin, compensating for the freshening effect of precipitation and run-off from Arctic rivers; and
• drainage of dense shelf water from the Arctic shelves into the deep Eurasian basin, a process that affects the deep water properties in the convective gyres via exchanges through the Fram Strait.