Constraints on exchanges in the Arctic Mediterranean-do they exist and can they be of use?

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Liquid freshwater transport and Polar Surface Water characteristics in the East Greenland Current during the AO-02 Oden expedition

Author Posting. © Elsevier B.V. , 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Progress In Oceanography 78 (2008): 45-57, doi:10.1016/j.pocean.2007.06.002.Dynamical features of the East Greenland Current (EGC) are synthesized from a survey conducted by the Swedish icebreaker Oden during the International Arctic Ocean - 02 expedition (AO-02) in May 2002 with emphasis on the liquid freshwa- ter transport and Polar Surface Water. The data include hydrography and lowered Acoustic Doppler Current Profiler (LADCP) velocities in eight transects along the EGC, from the Fram Strait in the north to the Denmark Strait in the south. The survey reveals a strong confinement of the low-salinity polar water in the EGC to the continental slope/shelf—a feature of relevance for the stability of the thermo- haline circulation in the Arctic Mediterranean. The southward transport of liquid freshwater in the EGC was found to vary considerably between the sections, rang- ing between 0.01 and 0.1 Sverdrup. Computations based on geostrophic as well as LADCP velocities give a section-averaged southward freshwater transport of 0.06 Sverdrup in the EGC during May 2002. Furthermore, Oden data suggest that the liquid freshwater transport was as large north of the Fram Strait as it was south of the Denmark Strait.Financial support was provided by the Swedish Research Council (JN and GB), the Ivar Bendixson Foundation (JN), The European Commission programme ASOF-N (contract No EVK2-CT-2002-00139), ASOF-W (contract No EVK2- CT-2002-00149), DAMOCLES (contract No 0189509) (BR), the National Science Foundation (PW, through grant OPP-0352628) and a fellowship at the Woods Hole Oceanographic Institution’s Ocean and Climate Change Institute (PW)

Modified halocline water over the Laptev Sea continental margin : historical data analysis

Historical hydrographic data (1940s–2010) show a distinct cross-slope difference of the lower halocline water (LHW) over the Laptev Sea continental margins. Over the slope, the LHW is on average warmer and saltier by 0.2°C and 0.5 psu, respectively, relative to the off-slope LHW. The LHW temperature time series constructed from the on-slope historical records are related to the temperature of the Atlantic Water (AW) boundary current transporting warm water from the North Atlantic Ocean. In contrast, the on-slope LHW salinity is linked to the sea ice and wind forcing over the potential upstream source region in the Barents and northern Kara Seas, as also indicated by hydrodynamic model results. Over the Laptev Sea continental margin, saltier LHW favors weaker salinity stratification that, in turn, contributes to enhanced vertical mixing with underlying AW

Fram Strait and Greenland Sea transports, water masses, and water mass transformations 1999–2010 (and beyond)

The exchanges between the Nordic Seas and the Arctic Ocean are important for the ocean circulation and climate. Transports are here estimated using summer hydrographic data from the Greenland Sea and the Fram Strait. Geostrophic transports are computed from hydrographic sections at 75°N in the Greenland Sea and at about 79°N in the Fram Strait. Geostrophic velocities are adjusted with summer velocities derived from Argo floats, and four conservation constraints are applied to a box closed by the two sections. The estimated net volume transports are 0.8 ± 1.5 Sv southward. Net freshwater transports through the Greenland Sea section are estimated at 54 ± 20 mSv and through the Fram Strait section at 66 ± 9 mSv. Heat loss in the area between the two sections is estimated at 9 ± 12 TW. Convection depths in the Greenland Sea are estimated from observations and vary between about 200 and 2000 dbar showing no trend. Water mass properties in the Greenland Sea are affected both by convection and lateral mixing. Vertical mixing is estimated from hydrography and based on it about 1 Sv of diluted Arctic Ocean waters are estimated to enter the Greenland Sea. The properties of Atlantic, intermediate, and deep waters are studied. Deep water properties are defined using water mass triangles and are subject to decadal changes

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

Abstract. The first-ever conductivity–temperature–depth (CTD) observations on the Wandel Sea shelf in northeastern Greenland were collected in April–May 2015. They were complemented by CTDs taken along the continental slope during the Norwegian FRAM 2014–2015 drift. The CTD profiles are used to reveal the origin of water masses and interactions with ambient water from the continental slope and the tidewater glacier outlet. The subsurface water is associated with the Pacific water outflow from the Arctic Ocean. The underlying halocline separates the Pacific water from a deeper layer of polar water that has interacted with the warm Atlantic water outflow through the Fram Strait, recorded below 140 m. Over the outer shelf, the halocline shows numerous cold density-compensated intrusions indicating lateral interaction with an ambient polar water mass across the continental slope. At the front of the tidewater glacier outlet, colder and turbid water intrusions were observed at the base of the halocline. On the temperature–salinity plots these stations indicate a mixing line that is different from the ambient water and seems to be conditioned by the ocean–glacier interaction. Our observations of Pacific water are set within the context of upstream observations in the Beaufort Sea and downstream observations from the Northeast Water Polynya, and clearly show the modification of Pacific water during its advection across the Arctic Ocean. Moreover, ambient water over the Wandel Sea slope shows different thermohaline structures indicating the different origin and pathways of the on-shore and off-shore branches of the Arctic Ocean outflow through the western Fram Strait. </jats:p