Abstract
Abstract. Conductivity–temperature–depth (CTD) transects across continental slope of the Eurasian Basin and the St. Anna Trough performed during NABOS (Nansen and Amundsen Basins Observing System) project in 2002–2015 and a transect from the 1996 Polarstern expedition are used to describe the temperature and salinity characteristics and volume flow rates (volume transports) of the current carrying the Atlantic water (AW) in the Arctic Ocean. The variability of the AW on its pathway along the slope of the Eurasian Basin is investigated. A dynamic Fram Strait branch of the Atlantic water (FSBW) is identified in all transects, including two transects in the Makarov Basin (along 159∘ E), while the cold waters on the eastern transects along 126, 142, and 159∘ E, which can be associated with the influence of the Barents Sea branch of the Atlantic water (BSBW), were observed in the depth range below 800 m and had a negligible effect on the spatial structure of isopycnic surfaces. The geostrophic volume transport of AW decreases farther away from the areas of the AW inflow to the Eurasian Basin, decreasing by 1 order of magnitude in the Makarov Basin at 159∘ E, implying that the major part of the AW entering the Arctic Ocean circulates cyclonically within the Nansen and Amundsen basins. There is an absolute maximum of θmax (AW core temperature) in 2006–2008 time series and a maximum in 2013, but only at 103∘ E. Salinity S(θmax) (AW core salinity) time series display a trend of an increase in AW salinity over time, which can be referred to as an AW salinization in the early 2000s. The maxima of θmax and S(θmax) in 2006 and 2013 are accompanied by the volume transport maxima. The time average geostrophic volume transports of AW are 0.5 Sv in the longitude range 31–92∘ E, 0.8 Sv in the St. Anna Trough, and 1.1 Sv in the longitude range 94–107∘ E.
Highlights
Atlantic water (AW) enters the Eurasian Basin in two branches: one branch originates from the Greenland and Norwegian seas and flows to the basin through Fram Strait, and the other reaches the deep part of the Arctic Ocean near St
The present results show that the increase in the temperature of the AW in 2006 was accompanied by an increase in volume transport
Fram Strait branch of the Atlantic water (FSBW) was present at all transects, including the two transects in the Makarov Basin (159◦ E), while the cold waters at the transects along longitudes 126, 142, and 159◦ E, which can be associated with the influence of the Barents Sea branch of the Atlantic water (BSBW), were observed in the depth range below 800 m and had little effect on the spatial structure of isopycnic surfaces and the horizontal gradient of density
Summary
Atlantic water (AW) enters the Eurasian Basin in two branches (see, e.g., Aagaard, 1981; Rudels et al, 1994, 1999, 2006, 2015; Schauer et al, 1997, 2002a, b; BerzczynskaMöller et al, 2012; Rudels, 2015; Dmitrenko et al, 2015; Pnyushkov et al, 2015, 2018b): one branch originates from the Greenland and Norwegian seas and flows to the basin through Fram Strait (the Fram Strait branch of the Atlantic water, hereinafter the FSBW), and the other reaches the deep part of the Arctic Ocean near St. Anna Trough after passing through the Barents Sea (the Barents Sea branch of the Atlantic water, hereinafter the BSBW). A number of sections in different years were made in the same re-
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