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Hydrographic measurements from ships, autonomous profiling floats, and instrumented seals over the period 1986–2016 are used to examine the temporal variability in open-ocean convection in the Greenland Sea during winter. This process replenishes the deep ocean with oxygen and is central to maintaining its thermohaline properties. The deepest and densest mixed layers in the Greenland Sea were located within its cyclonic gyre and exhibited large interannual variability. Beginning in winter 1994, a transition to deeper (>500 m) mixed layers took place. This resulted in the formation of a new, less dense class of intermediate water that has since become the main product of convection in the Greenland Sea. In the preceding winters, convection was limited to <300-m depth, despite strong atmospheric forcing. Sensitivity studies, performed with a one-dimensional mixed layer model, suggest that the deeper convection was primarily the result of reduced water-column stability. While anomalously fresh conditions that increased the stability of the upper part of the water column had previously inhibited convection, the transition to deeper mixed layers was associated with increased near-surface salinities. Our analysis further suggests that the volume of the new class of intermediate water has expanded in line with generally increased depths of convection over the past 10–15 years. The mean export of this water mass from the Greenland Sea gyre from 1994 to present was estimated to be 0.9 ± 0.7 Sv (1 Sv ≡ 106 m3 s−1), although rates in excess of 1.5 Sv occurred in summers following winters with deep convection. [ABSTRACT FROM AUTHOR]

Considered are the results of studying the variability of water thermohaline structure at different time scales. Time series and cross-sections are analyzed in the chosen test areas and trends are obtained. The analysis of autocorrelation functions and spectral density of the data enabled identifying the main periods of the variability of temperature and salinity in each area under study. The area of the 'dome' of bottom and deep waters is considered in detail. The TS-analysis and analysis of spatial cross-sections were carried out to study comprehensively the processes of salinization and warming of water in the recent two decades. The effects of advection from the adjacent areas are also studied by means of cross-correlation and wavelet analyses. [ABSTRACT FROM AUTHOR]

The Boreas Basin is located in the Norwegian-Greenland Sea between Northeast Greenland and Svalbard. Towards the east, it is bounded by the ultraslow mid-ocean Knipovich Ridge. Here, we present a 340-km-long seismic refraction line acquired during the expedition ARK-XXIV/3 of research vessel Polarstern in 2009, using 18 ocean bottom seismometers. It crosses the central Boreas Basin from the Knipovich Ridge to the Northeast Greenland margin. Thus, the line provides the first reliable crustal structure information of this basin. In addition, the gravity data acquired parallel to the seismic refraction line are used to calculate a 2.5-D gravity model. The P-wave velocity model shows an unusual ∼3-km-thin oceanic crust with seismic velocities less than 6.3 km s−1, indicating the absence of a significant oceanic layer 3. Mantle velocities vary between 7.5 km s−1 in the uppermost mantle and 8.0 km s−1 at approximately 15 km depth. The low velocities within the upper mantle may be explained by 13 per cent serpentinisation, which is negligible at about 15 km depth. Furthermore, the S-wave velocity model shows low Vp/Vs ratios in the mantle, indicating a highly serpentinised mantle at shallow depths. The gravity model has crustal densities between 2.3 and 2.9 g cm−3, which also point towards the absence of a significant thick oceanic layer 3. The results of our seismic refraction line and other geophysical data indicate that the entire Boreas Basin opened at ultraslow spreading rates since at least ∼28 Ma. No evidence for an extinct spreading ridge in the centre of the Boreas Basin was found. [ABSTRACT FROM AUTHOR]

The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009–2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25–45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem. [Copyright &y& Elsevier]

Abstract: A bioenergetics Individual Based Model (IBM) is developed to simulate the early growth (age 0 to 43d) of Arctic cod hatched from mid-May to mid-July in the Northeast Water (NEW) in 1993 and the North Water (NOW) in 1998. In the model, the growth of a virtual larva is forced by observed temperature and prey concentrations as dictated by its hatch date. The functional response of food consumption to temperature in the range −1.8 to +1.6°C was estimated based on the gut content of field-captured larvae. A sensitivity analysis indicated that high prey concentrations could compensate the depressing effect of low temperature on growth and vice-versa. The IBM reproduced well the observed differences in mean length-at-age between the two polynyas/years, in particular the poor growth in the North Water. In the NEW, a temporal match between yolk exhaustion and good feeding conditions occurred for early hatchers (abundant prey — medium temperature) and mid-season hatchers (medium prey — high temperature), which reached the largest sizes. In the NOW, prey concentrations were generally low at yolk exhaustion and variations in growth among cohorts depended essentially on temperature. Sub-sampling the model output to mimic the limited temporal resolution of sampling at sea reduced the variability in virtual growth and increased the match between simulated and observed variances in length-at-age. The IBM nevertheless underestimated the observed exceptional growth during match events. [Copyright &y& Elsevier]

The article offers information on the fetal growth of narwhal (Monodon monoceros), a High Arctic cetacean that separated between ice free waters summering grounds and pack ice wintering grounds in northern Canada and Greenland and Baffin Bay and the Greenland Sea, respectively. It says that narwhal subpopulations structure maintenance to summering grounds is based on reproductive isolation, while prevented by genetic identification of stocks. It adds that narwhals dispersed widely in winter.

Dechlorane Plus (DP), a highly chlorinated flame retardant, was investigated in marine boundary layer air and surface seawater from East Greenland Sea and in the Northern and Southern Atlantic toward Antarctica. The concentrations of DP ranged from 0.05 to 4.2 pg m-3 in the atmosphere and from

The endemic aquatic acritarch Decahedrella martinheadii is confined to the Atlantic sector of the high northern latitudes in the Miocene and has been previously considered as useful for biostratigraphy and paleoenvironmental interpretations in temperate to cold water environments. Stimulated by its recovery in Neogene sediments from the Lomonosov Ridge (Central Arctic Ocean) during IODP Expedition 302, the stratigraphic and biogeographic distribution has been compiled to revise its age range based on the Astronomically Tuned Neogene Time Scale 2004, and to assess its paleoecologic affinities. The biostratigraphic revision reveals that this species is restricted to the late Middle to Late Miocene. The first appearance is inconsistent at the various sites but was probably in sediments younger than 13 Ma, whereas the last appearance is a relatively well-constrained datum in the Norwegian-Greenland Sea at around 6.2 Ma. Decahedrella martinheadii was particularly abundant and had its widest biogeographic distribution in the northwestern North Atlantic Ocean, the Norwegian-Greenland Sea, the Fram Strait and the Central Arctic Ocean in the Late Miocene suggesting that it was adapted to temperate to cold seasonally ice-covered surface waters. This species evolved during the global cooling after the mid-Miocene thermal optimum, and it became extinct when small-scale glaciations developed in the Northern Hemisphere in the latest Miocene. Moreover, fundamental reorganisations of the circulation system and the water mass characteristics may have affected the distribution of this species. [ABSTRACT FROM AUTHOR]

A preindustrial climate experiment was conducted with the third version of the CNRM global atmosphere–ocean–sea ice coupled model (CNRM-CM3) for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). This experiment is used to investigate the main physical processes involved in the variability of the North Atlantic ocean convection and the induced variability of the Atlantic meridional overturning circulation (MOC). Three ocean convection sites are simulated, in the Labrador, Irminger and Greenland–Iceland–Norwegian (GIN) Seas in agreement with observations. A mechanism linking the variability of the Arctic sea ice cover and convection in the GIN Seas is highlighted. Contrary to previous suggested mechanisms, in CNRM-CM3 the latter is not modulated by the variability of freshwater export through Fram Strait. Instead, the variability of convection is mainly driven by the variability of the sea ice edge position in the Greenland Sea. In this area, the surface freshwater balance is dominated by the freshwater input due to the melting of sea ice. The ice edge position is modulated either by northwestward geostrophic current anomalies or by an intensification of northerly winds. In the model, stronger than average northerly winds force simultaneous intense convective events in the Irminger and GIN Seas. Convection interacts with the thermohaline circulation on timescales of 5–10 years, which translates into MOC anomalies propagating southward from the convection sites. [ABSTRACT FROM AUTHOR]

This paper reviews published information on the timing of hydrographic and atmospheric variations in the Iceland and Greenland Seas. Large scale variations in hydrography, advection features, regional convection and their general impact or connection with climate and hydro-biological conditions will be considered briefly in the area of the Subarctic Gyre in the northern North Atlantic and the Nordic Seas. The intermediate convection in the Iceland Sea may have ceased during the so-called “ice years” in North Icelandic waters in the late sixties (1965–1970). Convection to the bottom in the Greenland Sea seems to have ceased in the seventies or after 1972. A clear linkage between the period of the “Great Salinity Anomaly”, that was first observed in the Iceland Sea around 1968 and was advected through the Subarctic Gyre and returned to East Greenland waters and North Icelandic waters in 1981, and the timing of reduction of convection in the Greenland Sea is thus not obvious. Further detailed analysis is needed to resolve the questions about processes involved in the variability of hydrographic conditions in the northern North Atlantic and the Nordic Seas. It should be noted that conditions for convection may not only be related to atmospheric conditions or large scale advection of water characteristics but also to regional or local hydrographic conditions. [ABSTRACT FROM PUBLISHER]