The first oceanographic section across the Nansen Basin in the Arctic Ocean

The first quasi-synoptic oceanographic section across a major deep basin of the Arctic Ocean reveals three different regimes: a narrow boundary current system along the northern Barents Shelf slope, a wide interior basin regime and a northern boundary curret regime with several distinct cores along the Nansen-Gakkel Ridge at 86°N. The southern boundary current cores are marked by high oxygen concentrations, high salinities and low temperatures that indicate sources on the shelf and in Fram Strait. The northern boundary current regime contains water mass signatures that are thought to come from the Amundsen Basin as well as from Fram Strait. The Nansen Basin interior is only slowly ventilated from the boundary currents and shelves, the deep water having an age of several decades. At 83°N characteristics change abruptly from those representative of the southern half of the section to those typical for the northern half and deep Arctic basins. Waters of the southern half of the basin, which have a strong melt-water component in their surface layers, largely originate directly in Fram Strait River runoff from the Siberian rivers and sea ice from the Laptev Sea contributes to the northern part of our section.