Arctic Ocean circulation and variability – advection and external forcing encounter constraints and local processes

Abstract

Abstract. The first hydrographic data from the Arctic Ocean, the section from the Laptev Sea to the passage between Greenland and Svalbard obtained by Nansen on his drift with Fram 1893-1896, aptly illustrate the main features of Arctic Ocean oceanography and indicate possible processes active in transforming the water masses in the Arctic Ocean. Many, perhaps most, processes were identified already by Nansen, who put his mark on almost all subsequent research in the Arctic. Here we shall revisit some key questions and follow how our understanding has evolved from the early 20th century to present. What questions, if any, can now be regarded as solved and which remain still open? Five different but connected topics will be discussed: (1) The low salinity surface layer and the storage and export of freshwater. (2) The vertical heat transfer from the Atlantic water to sea ice and to the atmosphere. (3) The circulation and mixing of the two Atlantic inflow branches. (4) The formation and circulation of deep and bottom waters in the Arctic Ocean. (5) The exchanges through Fram Strait. Foci will be on the potential effects of increased freshwater input and reduced sea ice export on the freshwater storage and residence time in the Arctic Ocean, on the deep waters of the Makarov Basin, and on the circulation and relative importance of the two inflows, over the Barents Sea and through Fram Strait, for the distribution of heat in the intermediate layers of the Arctic Ocean.

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

“…The basic reason for the flow direction is a higher steric sea level in the Pacific compared to the Atlantic, giving rise to a wide trans-Arctic drift from the Bering Strait to the Fram Strait. In the Atlantic sector, the Canadian Arctic Archipelago is an export gateway for water volume and for freshwater (Rudels, 2012). The Fram Strait features southward transport of freshwater, salt and sea ice.…”

Arctic Ocean outflow and glacier–ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland)

“…The Atlantic Water outflow through the western Fram Strait with temperatures above 0 • C in the intermediate water layer (> 150-200 m) closes the circulation loop of the Atlantic Water in the Arctic Ocean conditioned by its inflow through the eastern Fram Strait and Barents Sea (e.g., Rudels et al, 1994;Rudels, 2012) - Fig. 1.…”

“…Station Nord features a very cold polar tundra climate with an average temperature dur- Figure 1. Schematic circulation of the Atlantic Water (AW, red arrows) and Pacific water (PcW, white arrows) in the Arctic Ocean and adjoining Greenland Sea following Rudels et al (1994), Jones (2001), Rudels (2012) and Woodgate (2013). The dashed and dotted red arrows correspond to the Fram Strait and Barents Sea branches of the AW inflow, respectively.…”

Central Arctic Ocean paleoceanography from ∼ 50 ka to present, on the basis of ostracode faunal assemblages from the SWERUS 2014 expedition

“…1b). The following summary of Arctic water masses and circulation is taken from Aagaard and Carmack (1989), Anderson et al (1994), Jones (2001), Olsson and Anderson (1997) and Rudels et al (2012Rudels et al ( , 2013. Arctic Ocean water masses include a fresh, cold Polar Surface Water layer (PSW; T =∼ 0 to −2 • C, S =∼ 32 to 34), found between ∼ 0 and 50 m. The PSW is characterized by perennial ice in most regions and seasonal sea ice in the margins of the Arctic Ocean.…”