Search

The Greenland Sea intermediate waters transported via the Jan Mayen Channel (JMCh) are a significant source for the Iceland-Scotland Overflow Water. Based on hydrographic data collected by a Norway-China survey in 2015 and Argo floats, we classify the water masses of the Greenland Sea outflow and then reveal their distributions in the Norwegian Sea. The Atlantic-origin water produced by density increase during winter in the northern Greenland Sea was an important component of the intermediate waters exported to the Norwegian Sea, accounting for about 30% of the total volume in 2015. The hydrographic data revealed that the major passage of outflow from the Greenland Sea was located in the southern Mohn Ridge in 2015, rather than in the JMCh, as generally recognized. The transport of intermediate waters from the Greenland Sea via the southern Mohn Ridge in the summer of 2015 is estimated to be about 0.8--1.7 Sv. This transport pattern provides a perspective that there exists a multi-passage system of outflow in the JMCh and Mohn Ridge, promoting a stable supply of intermediate waters to the Norwegian Sea. [ABSTRACT FROM AUTHOR]

Climate model projections suggest a substantial decrease of sea ice export into the outflow areas of the Arctic Ocean over the 21st century. Fram Strait, located in the Greenland Sea sector, is the principal gateway for ice export from the Arctic Ocean. The consequences of lower sea ice flux through Fram Strait on ocean dynamics and primary production in the Greenland Sea remain unknown. By using the most recent 16 years (2003–2018) of satellite imagery available and hydrographic in situ observations, the role of exported Arctic sea ice on water column stratification and phytoplankton production in the Greenland Sea is evaluated. Years with high Arctic sea ice flux through Fram Strait resulted in high sea ice concentration in the Greenland Sea, stronger water column stratification, and an earlier spring phytoplankton bloom associated with high primary production levels. Similarly, years with low Fram Strait ice flux were associated with a weak water column stratification and a delayed phytoplankton spring bloom. This work emphasizes that sea ice and phytoplankton production in subarctic "outflow seas" can be strongly influenced by changes occurring in the Arctic Ocean. Plain Language Summary: As the Arctic atmosphere and ocean warm, Arctic sea ice continues to decline. The Greenland Sea (to the east of Greenland) is heavily influenced by sea ice leaving the Arctic Ocean. In this study, we address the impacts of sea ice exiting the Arctic on the development of free‐floating microscopic algae in the Greenland Sea. For this, we analyzed 16 years of data from satellite images and autonomous ocean robots. Our results reveal that changes in the quantity of sea ice leaving the Arctic Ocean in spring modify the environment and development of microscopic algae. These algae are important because they capture carbon dioxide and support ocean life; this paper can help to predict how they will respond to the ongoing environmental changes occurring in the Arctic. Key Points: A positive relationship exists between exported Arctic sea ice and the sea ice distribution in the Greenland SeaHigh (low) springtime export of Arctic sea ice may increase (reduce) the stratification of the Greenland BasinA strong (weak) salinity stratification of the Greenland Basin induces an early (late) phytoplankton spring bloom and primary production [ABSTRACT FROM AUTHOR]

Multimodel Arctic Ocean "climate response function" experiments are analyzed in order to explore the effects of anomalous wind forcing over the Greenland Sea (GS) on poleward ocean heat transport, Atlantic Water (AW) pathways, and the extent of Arctic sea ice. Particular emphasis is placed on the sensitivity of the AW circulation to anomalously strong or weak GS winds in relation to natural variability, the latter manifested as part of the North Atlantic Oscillation. We find that anomalously strong (weak) GS wind forcing, comparable in strength to a strong positive (negative) North Atlantic Oscillation index, results in an intensification (weakening) of the poleward AW flow, extending from south of the North Atlantic Subpolar Gyre, through the Nordic Seas, and all the way into the Canadian Basin. Reconstructions made utilizing the calculated climate response functions explain ∼50% of the simulated AW flow variance; this is the proportion of variability that can be explained by GS wind forcing. In the Barents and Kara Seas, there is a clear relationship between the wind‐driven anomalous AW inflow and the sea ice extent. Most of the anomalous AW heat is lost to the atmosphere, and loss of sea ice in the Barents Sea results in even more heat loss to the atmosphere, and thus effective ocean cooling. Release of passive tracers in a subset of the suite of models reveals differences in circulation patterns and shows that the flow of AW in the Arctic Ocean is highly dependent on the wind stress in the Nordic Seas. Plain Language Summary: The North Atlantic Current is an extension of the Gulf Stream, which brings warm Atlantic Water northward as the current flows through the Nordic Seas. Eventually, it enters the cold deep Arctic Ocean basins through the Barents Sea and Fram Strait. Nine different numerical ocean ice models have been analyzed and compared in order to investigate (1) their ability to simulate this northward flow of Atlantic Water, (2) its dependence on wind forcing, and (3) its impact on Arctic sea ice. Consistently, in all models, stronger winds in the Greenland Sea result in a stronger northward flow of warm Atlantic Water. The response on ocean circulation occurs from the North Atlantic, through the Nordic Seas and the Barents Sea, to the deep Canadian Basin. The flow of warm Atlantic Water within the Arctic Ocean is thus highly dependent on the wind stress in the Nordic Seas. There is particularly clear response in the Barents and Kara Seas where a wind‐driven anomalous warm inflow drives a smaller sea ice extent and thickness, and an increased heat transfer from the ocean to the atmosphere above. Weaker winds in the Greenland Sea produces weaker flow and hence a larger sea ice extent and thickness. Key Points: Stronger/weaker winds over the Greenland Sea result in stronger/weaker flow of Atlantic Water in the Nordic Seas and into the Arctic OceanIn the Barents Sea there is a linear relationship between Atlantic Water volume and heat transport, surface heat loss, and sea ice extentThere is potential for predictability of the Arctic‐Atlantic circulation based on wind forcing anomalies and climate response functions [ABSTRACT FROM AUTHOR]

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]

Abstract: Atlantic Water (AW) transported from the Nordic Seas is the major source of oceanic heat to the Arctic Ocean. Based on results from the TOPAZ reanalysis, a regional coupled ice‐ocean data assimilation system, we show that interannual variability of AW temperature in the Fram Strait (FS) is associated with the strength of the Greenland Sea gyre (GSG) circulation. The response of the GSG to the anomalous wind stress curl over the Nordic Seas modifies the AW inflow and thus influences the variability of AW temperature in the FS. A stronger (weaker) GSG circulation increases (decreases) the AW flow speed toward FS, leading to increased (decreased) oceanic heat content and higher (lower) AW temperature therein. This implies that the Nordic Seas circulation is not only a passive conduit of AW, but its response to overlying atmospheric variability can also largely influence the AW temperature in the FS by modifying the transport of AW. [ABSTRACT FROM AUTHOR]

During summer 2014 and summer 2015 two autonomous Seagliders were operated over several months close to the ice edge of the East Greenland Current to capture the near-surface fresh water distribution in the western Greenland Sea. The mission 2015 included an excursion onto the East Greenland Shelf into the Norske Trough. Temperature, salinity and drift data were obtained in the upper 500 to 1000 m with high spatial resolution. At AWI the data processing for these glider measurements was conducted. The first part consists of the Seaglider Toolbox from the University of Each Anglia, the second was exclusively composed for the data from the Greenland Sea. The final hydrographic, position and drift data sets can be downloaded from https://doi.org/10.1594/PANGAEA.893896. [ABSTRACT FROM AUTHOR]

The hypothesis that Arctic tidal pools provide environmental conditions suitable for calcifiers during summer, thereby potentially providing refugia for calcifiers in an acidifying Arctic Ocean, was tested on the basis of measurements conducted during two midsummers (2014 and 2016) in tidal pools colonised by a community composed of macroalgae and calcifiers in Disko Bay, Greenland (69° N). The tidal pools exhibited steep diurnal variations in temperature from a minimum of about 6 °C during the night to a maximum of almost 18 °C in the afternoon, while the temperature of the surrounding shore water was much lower, typically in the range 3 to 8 °C. O2 concentrations in the tidal pools were elevated relative to those in the adjacent open waters, by up to 11 mg O2 L−1, and exhibited heavy super-saturation (up to > 240%) during daytime emersion, reflecting intense and sustained photosynthetic rates of the tidal macroalgae. The intense photosynthetic activity of the seaweeds resulted in the drawdown of pCO2 concentrations in the pools during the day to levels down to average (±SE) values of 66 ± 18 ppm, and a minimum recorded value of 14.7 ppm, corresponding to pH levels as high as 8.69 ± 0.08, as compared to CO2 levels of 256 ± 4 and pH levels of 8.14 ± 0.01 in the water flooding the pools during high tide. The corresponding Ωarag reached 5.04 ± 0.49 in the pools as compared to 1.55 ± 0.02 in the coastal waters flooding the pools. Net calcification averaged 9.6 ± 5.6 μmol C kg−1 h−1 and was strongly and positively correlated with calculated net ecosystem production rates, which averaged 27.5 ± 8.6 μmol C kg−1 h−1. Arctic tidal pools promote intense metabolism, creating conditions suitable for calcification during the Arctic summer, and can, therefore, provide refugia from ocean acidification to vulnerable calcifiers as extended periods of continuous light during summer are conducive to suitable conditions twice a day. Meroplankton larvae are exposed to ocean acidification until they settle in vegetated tidal pools, where they benefit from the protection offered by the “macroalgae-carbonate saturation state” interaction favouring calcification rates. [ABSTRACT FROM AUTHOR]

Liu, X. and Zhang, L., 2018. Study on optimization of sea ice concentration with adjoint method. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 44–50. Coconut Creek (Florida), ISSN 0749-0208. Obtaining initial sea ice concentration (SIC) values with high accuracy that are consistent with other models have been a hot topic in both sea ice prediction and sea ice modeling studies. Here, an ocean-sea ice coupled numerical model and its adjoint code have been utilized to carry out numerical experiments to optimize the initial SIC values. In the experiments, the cost function was defined as the difference between the SIC values from the reanalysis dataset and the modeled results. The gradient of cost function, relative to SIC and other model variables, was computed by the adjoint model, and a linear search algorithm was employed to optimize the SIC values by minimizing the cost function. The influences of the weight coefficients of the cost function, the extent of the geographical region, and the seawater temperature and sea ice thickness initial values on the optimization results have been analyzed. The weight coefficients of the cost function had little effect on the SIC distribution pattern but substantial influence on the SIC values. The optimized SIC in the Greenland Sea, Okhotsk Sea, and the Arctic Ocean, with a constant weight coefficient, is better than that with variable weight coefficients. The errors in the initial model fields, other than SIC, may deteriorate the overall result, implying that optimizing multiple model fields simultaneously may improve the optimization effect. Decreasing the size of the geographical region for optimization does not improve the SIC optimization results substantially. Compared to the results from a global cost function, the Barents Sea SIC values from a northern hemispheric cost function are poorly optimized. [ABSTRACT FROM AUTHOR]

Variations in sea ice freeze onset and regional sea surface temperatures (SSTs) in Baffin Bay and Greenland Sea are linked to autumn surface air temperatures (SATs) around coastal Greenland through 500 hPa blocking patterns, 1979-2014. We find strong, statistically significant correlations between Baffin Bay freeze onset and SSTs and SATs across the western and southernmost coastal areas, while weaker and fewer significant correlations are found between eastern SATs, SSTs, and freeze periods observed in the neighboring Greenland Sea. Autumn Greenland Blocking Index values and the incidence of meridional circulation patterns have increased over the modern sea ice monitoring era. Increased anticyclonic blocking patterns promote poleward transport of warm air from lower latitudes and local warm air advection onshore from ocean-atmosphere sensible heat exchange through ice-free or thin ice-covered seas bordering the coastal stations. Temperature composites by years of extreme late freeze conditions, occurring since 2006 in Baffin Bay, reveal positive monthly SAT departures that often exceed 1 standard deviation from the 1981-2010 climate normal over coastal areas that exhibit a similar spatial pattern as the peak correlations. [ABSTRACT FROM AUTHOR]

Bacterial production rates were measured in water profiles collected in the Greenland Sea and adjacent areas. Hydrography and nutrients throughout the water column were measured along 75°N from 12°W to 10°E at 20 km distance intervals. Net primary production rates from satellite sensed data were compared with literature values from 14 C incubations and used for regional and seasonal comparisons. Maximum bacterial production rates were associated with the region close to the edge of the East Greenland current, and the rates decreased gradually towards the center of the Greenland Sea central gyre. Integrated over the upper 20 m the maximum bacterial production rate was 17.9 mmol C m − 2 day − 1 , and east of the center of the gyre the average integrated rate was 4.6 mmol C m − 2 day − 1 . It is hypothesized that high bacterial production rates in the western Greenland Sea were sustained by organic material carried from the Arctic Ocean by the East Greenland Current. The depth profiles of nitrate and phosphate were very similar both sides of the Arctic front, with 2% higher values between 500 m and 2000 m in the Arctic domain, and a N/P ratio of 13.6. The N/Si ratio varied by depth and region, with increasing silicate depletion from 1500 m depth to the surface. The rate of depletion from 1500 m depth to surface in the Atlantic domain was twice as high as in the Arctic domain. Net primary production rates in the area between the edge of the East Greenland current and the center of the Greenland Sea gyre was 96 mmol C m − 2 day − 1 at the time of the expedition in 2006, and 78 mmol C m − 2 day − 1 east of the center including the Atlantic domain. Annual net primary production estimated from satellite data in the Greenland Sea increased substantially in the period between 2003 and 2016, and the rate of increase was lowest close to the East Greenland Current. [ABSTRACT FROM AUTHOR]

Sea-to-air fluxes of marine biogenic aerosols have the potential to modify cloud microphysics and regional radiative budgets, and thus moderate Earth's warming. Polar regions play a critical role in the evolution of global climate. In this work, we use a well-established biogeochemical model to simulate the DMS flux from the Greenland Sea (20°W–10°E and 70°N–80°N) for the period 2003–2004. Parameter sensitivity analysis is employed to identify the most sensitive parameters in the model. A genetic algorithm (GA) technique is used for DMS model parameter calibration. Data from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are used to drive the DMS model under 4 × CO 2 conditions. DMS flux under quadrupled CO 2 levels increases more than 300% compared with late 20th century levels (1 × CO 2 ). Reasons for the increase in DMS flux include changes in the ocean state—namely an increase in sea surface temperature (SST) and loss of sea ice—and an increase in DMS transfer velocity, especially in spring and summer. Such a large increase in DMS flux could slow the rate of warming in the Arctic via radiative budget changes associated with DMS-derived aerosols. [ABSTRACT FROM AUTHOR]

Harp Pagophilus groenlandicus and hooded Cystophora cristata seals are important predators in drift ice areas of the Greenland Sea (the West Ice) during spring and summer. Their summer (June-July) diet was studied in the West Ice in 2008 and 2010, based on analysis of the gastrointestinal contents of 179 and 20 hooded and harp seals, respectively, in addition to 70 harp seal faeces samples. The diet compositions of harp and hooded seals deviated significantly from each other, implying that the degree of food competition was relatively low. Polar cod Boreogadus saida dominated the hooded seal diet and amphipods (mostly Themisto sp.) dominated the harp seal diet. Krill and the squid Gonatus fabricii were eaten by both species. The importance of G. fabricii for hooded seals was lower in this study compared with previous studies, and krill only occurred sparsely. The occurrence of polar cod, Themisto sp. and krill in the diets of the two seal species coincides well with the geographical and vertical distribution of these three prey items and the previously recorded dive depths of the seals. The inclusion of demersal fishes such as sculpins and snailfish in the diet of some hooded seals was more likely a result of increased availability rather than changes in prey preference, as these seals were collected above shallower waters. Both species showed a rather narrow niche breadth. [ABSTRACT FROM AUTHOR]

Arctic marine ecosystems are disproportionately impacted by global warming. Sea ice plays an important role in the regional climate system and the loss of perennial sea ice has diverse ecological implications. Here we investigate the causes of an unusually early and strong phytoplankton bloom in the northern Greenland Sea (20°W–10°E, 75°N–80°N) during the 2010 season. In order to better understand the anomalous bloom in 2010, we examine the correlation between satellite-derived biomass and several possible environmental factors for the period 2003–2012. Results show that the timing of sea ice melt played an important role in promoting the growth of phytoplankton. Multivariate lagged regression analysis shows that phytoplankton biomass (CHL) is correlated with ice concentration (ICE) and ice melting, as well as sea surface temperature (SST) and photosynthetically active radiation (PAR). During 2010, the spring peak in biomass came much earlier and achieved a higher value than most other years in the satellite archive record, which was due to earlier and more extensive sea ice melt in that year. Relative lower SST and PAR in spring and early summer in year 2010 associated with a persistent negative North Atlantic Oscillation (NAO) index were possible drivers of the bloom. Wind direction changed from the southeast to southwest direction in spring, possibly transporting nutrient enriched melt runoff from glaciers on Greenland and other sources from the south to northern coastal regions. [ABSTRACT FROM AUTHOR]

Microplastics have been reported everywhere around the globe. With very limited human activities, the Arctic is distant from major sources of microplastics. However, microplastic ingestions have been found in several Arctic marine predators, confirming their presence in this region. Nonetheless, existing information for this area remains scarce, thus there is an urgent need to quantify the contamination of Arctic marine waters. In this context, we studied microplastic abundance and composition within the zooplankton community off East Greenland. For the same area, we concurrently evaluated microplastic contamination of little auks ( Alle alle ), an Arctic seabird feeding on zooplankton while diving between 0 and 50 m. The study took place off East Greenland in July 2005 and 2014, under strongly contrasted sea-ice conditions. Among all samples, 97.2% of the debris found were filaments. Despite the remoteness of our study area, microplastic abundances were comparable to those of other oceans, with 0.99 ± 0.62 m −3 in the presence of sea-ice (2005), and 2.38 ± 1.11 m −3 in the nearby absence of sea-ice (2014). Microplastic rise between 2005 and 2014 might be linked to an increase in plastic production worldwide or to lower sea-ice extents in 2014, as sea-ice can represent a sink for microplastic particles, which are subsequently released to the water column upon melting. Crucially, all birds had eaten plastic filaments, and they collected high levels of microplastics compared to background levels with 9.99 and 8.99 pieces per chick meal in 2005 and 2014, respectively. Importantly, we also demonstrated that little auks took more often light colored microplastics, rather than darker ones, strongly suggesting an active contamination with birds mistaking microplastics for their natural prey. Overall, our study stresses the great vulnerability of Arctic marine species to microplastic pollution in a warming Arctic, where sea-ice melting is expected to release vast volumes of trapped debris. [ABSTRACT FROM AUTHOR]

Field experimental data from a 1980s program in the Greenland Sea investigating the evolution of directional wave spectra in the marginal ice zone are reanalyzed and compared with the predictions of a new, phase-resolving, three-dimensional model describing the two-dimensional scattering of the waves by the vast number of ice floes that are normally present. The model is augmented with a dissipative term to account for the nonconservative processes affecting wave propagation. Observations reported in the experimental study are used to reproduce the ice conditions and wave forcing during the experiments. It is found that scattering alone underestimates the attenuation experienced by the waves during their passage through the ice field. With dissipation, however, the model can replicate the observed attenuation for most frequencies in the swell regime. Model predictions and observations of directional spreading are in agreement for short to midrange wave periods, where the wave field quickly becomes isotropic. For larger wave periods, little spreading can be seen in the model predictions, in contrast to the isotropic or near-isotropic seas reported in the experimental study. The discrepancy is conjectured to be a consequence of the inaccurate characterization of the ice conditions in the model and experimental errors. [ABSTRACT FROM AUTHOR]

Drifting icebergs and sea ice floes can be serious threats to offshore structures in the Arctic; however, information about their drift is limited. We performed GPS tracking of 9 icebergs and 10 ice floes in the Kanumas area of the Greenland Sea during 2012–2014. The obtained coordinates were used to analyse the drift trajectories, derived velocities, spectra and relative drift of the icebergs and sea ice. This paper presents statistical data on the drift velocities and demonstrates the differences between drifts in the shear ice zone and the central pack or marginal ice zone. The maximum drift speed reached by an iceberg was 1.66 m/s, which happened during strong southerly wind at 66°N. The relative drift of icebergs and adjacent sea ice is strongly dependent on ice conditions and wind, but also it is determined by the different types of applied drag forces. Then, spectral analysis revealed that GPS errors may prevent capturing processes faster than one cycle per hour. In addition, for the first time, we measured the rotation of four icebergs around their vertical axes. Icebergs make an average of between one and two revolutions per day under the periodic tidal current. However, the instantaneous angular velocity reached 0.001 rad/s at some moments. Finally, this paper proposes an iceberg drift model including the rotation. The modelling results are in good agreement with the measured evolution of the icebergs’ yaw angles. The drift data and the rotation model can be used when planning offshore activities in the area or as an input for numerical models involving sea ice. [ABSTRACT FROM AUTHOR]

Over the past decade, the diminishing Arctic sea ice has impacted the wave field which is principally dependent on the ice-free area and wind. This study characterizes the wave climate in the Arctic using detailed sea state information from a wave hindcast and merged altimeter dataset spanning 1992-2014. The wave model uses winds from the Climate Forecast System Reanalysis and ice concentrations derived from satellites as input. The ice concentrations have a grid spacing of 12.5 km, which is sufficiently able to resolve important features in the marginal ice zone. The model performs well, verified by the altimeters and is relatively consistent for climate studies. The wave seasonality and extremes are linked to the ice coverage, wind strength, and wind direction. This creates distinct features in the wind-seas and swells. The increase in wave heights is caused by the loss of sea ice and not the wind verified by the altimeters and model. However, trends are convoluted by inter-annual climate oscillations like the North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation. The Nordic-Greenland Sea is the only region with negative trends in wind speed and wave height and is related to the NAO. Swells are becoming more prevalent and wind-sea steepness is declining which make the impact on sea ice uncertain. It is inconclusive how important wave-ice processes are within the climate system, but selected events suggest the importance of waves within the marginal ice zone. [ABSTRACT FROM AUTHOR]

Arctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only affect local sea-ice formation, but also control the sea-ice transport from the Arctic Ocean through a sea-ice–ocean–atmosphere feedback mechanism. The role of solar forcing, however, appears to have been more ambiguous during an interval around AD 1500, after the transition from the Medieval Climate Anomaly to the Little Ice Age, likely to be driven by a range of factors. [ABSTRACT FROM AUTHOR]

Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes. [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 critically endangered Spitsbergen stock of bowhead whale ( Balaena mysticetus) seems to be increasing. However, research effort has also been increasing confounding a firm conclusion. A systematic aerial survey for walrus ( Odobaenus rosmarus), applying distance sampling methodology in part of the Northeast Water Polynya (NEW), revealed a 'bycatch' of several observations of bowhead whales, which resulted in an estimated abundance of 102 (95 % CI 32-329) individuals. This is the largest abundance of bowhead whales reported from the Greenland Sea since the days of whaling in the sixteenth to seventeenth centuries. The NEW was inaccessible to vessels during the whaling period because of heavy pack ice, and it is only recently that researchers have visited this area; thus only a few sightings of bowhead whales within the NEW exist prior to the survey in 2009. The NEW may nevertheless be one of the most important summering grounds for the Spitsbergen stock, and the whales may benefit from advection of calanoid copepods from the productive deep basins along the coast of Svalbard east of the NEW. This discovery provides renewed hope for the Spitsbergen stock of bowhead whales that until now has shown only inconclusive signs of recovery despite more than 100 years of protection from whaling. [ABSTRACT FROM AUTHOR]

The PS2644 deep-sea core sequence, retrieved from the northwestern margin of Iceland and covering the last 86 ka, exhibits high sedimentation rates during the last glacial cycle that allow the clear distinction of Greenland stadial (GS)/interstadial (GI) cycles in the various proxy records. Abundance records of rhyolitic, basaltic and tachylytic tephra grains reveal several maxima. Tephra grains of all types were geochemically analyzed in 44 levels. A total of 92 tephras with a distinctive character have been defined within the glacial sequence of gravity core PS2644-5, whereas the Holocene record is dominated by reworked Vedde Ash grains and not suitable for tephra stratigraphic work. Of the 92 tephras only 19 geochemical populations have been linked with confidence to previously defined tephras such as from the Vedde Ash, Faeroe Marine Ash Zones (FMAZ) II and III and North Atlantic Ash Zone (NAAZ) II. For the glacial period informal names were given to 78 new tephras, most of which are basaltic tephras. Several of these layers have a unique geochemical character and might become new chronostratigraphic markers in the North Atlantic region. Linking the tephra populations to the volcanic system producing them, respectively, revealed that Icelandic eruptions dominate with 83 tephra geochemical populations and Jan Mayen with 9. Around 48% of the informal tephra layers linked to the Icelandic volcanic province are produced from either the Grimsvötn or the Veidivötn-Bardarbunga volcanic systems. The intervals spanning from Greenland Stadial (GS) 3 to Greenland Interstadial (GI) 4 (24.5–29 ka BP), from GI 8 to GS 10 (36.9–40.5 ka BP) and from GI 14 to GI 15.2 (50–56 ka BP) are the periods with the highest number of eruptions, all of which are associated with known tephra zones. [ABSTRACT FROM AUTHOR]

We estimate temporal variation in fecundity, the reproduction rate, for Barents Sea and Greenland Sea harp seals using a state-space approach. A stochastic process model for fecundity is integrated with an age-structured population dynamics model and fit to available data for these two harp seal populations. Owing to scarceness of data, it is necessary to "borrow strength" from the Northwest Atlantic harp seal population in form of prior distributions on autocorrelation and variance in fecundity. Comparison is made to a simpler deterministic population dynamics model. The state-space model is more flexible and is able to account for the variations in the data. For Barents Sea harp seals, the state-space model gives a higher estimate of current population size but also a much higher associated uncertainty. In the Greenland Sea, the differences between the stochastic and deterministic models are much smaller. [ABSTRACT FROM AUTHOR]

The effect of submarine carbon dioxide (CO2) vents on seawater carbonate chemistry have been determined using hydrographical and marine carbonate data obtained from two submarine hydrothermal vent fields, as well as a reference station, all near the Jan Mayen Island in the Norwegian-Greenland Sea. We have shown that one can successfully determine the excess carbon that enters the seawater from the vents by applying a modified version of a back-calculation technique, which is traditionally used to study the invasion of excess atmospheric CO2 in the surface ocean. As a result of this excess carbon, total dissolved inorganic carbon ( CT) in the seawater surrounding the vents was on average 12 μmol kg−1 (1-30 μmol kg−1) higher compared to samples obtained from a reference station outside the venting areas. The observed excess CT was most significant between 100 m and 200 m but was noticeable in all depths with the exception of the upper 10-20 m. The absence of a venting CO2 signal in the surface water and the realism of the results are discussed. We believe the present method is promising for monitoring (detection and quantification) of CO2 leakage into the water column due to its high sensitivity and readiness for automation. [ABSTRACT FROM AUTHOR]

Relationships between solar activity and climate in the North Atlantic region have long been reported and, more recently, mechanisms have been proposed to explain these. Normally such relationships are tested over decadal time scales. Here, daily sea surface temperature fields bridging the period of exceptionally low solar activity between solar cycles 23 and 24 have been analysed. The day-to-day variability of the fields has been measured and the fields have been classified, using cluster analysis. The main water masses are clearly expressed, together with detail of their interactions. Three features relate to the level of solar activity. First, there is a statistically significant difference in the day-to-day variability of the sea surface temperature field between the period of lowest solar activity and the remaining periods. Second, during the transition from summer to winter, there are systematic, inter-annual changes in the day-to-day variability of the sea surface temperature field. Third, the forms of the late summer temperature fields exhibit symmetry about the years of lowest solar activity. These features are attributable to variability in the passage of weather systems. The influence on North Atlantic surface climate of variations in the solar ultraviolet band acting through the stratosphere has been reported in a number of studies. This provides a credible mechanism for solar activity influencing sea surface temperatures in the Greenland Sea. [ABSTRACT FROM AUTHOR]

The distribution at sea of upper trophic levels-seabirds and marine mammals-is depending on their food availability: high concentrations reflect high prey abundance and thus high biological production. Polar marine ecosystems are characterized by low biodiversity and high biological patchiness. The distribution of predators, as a consequence, shows a similar patchiness. During two expeditions of icebreaking RV Polarstern in June-July 2011, biodiversity in the arctic marine zone north of 70°N was very low, with low numbers of species: 20 seabirds, eight cetaceans, five pinnipeds and polar bear. Moreover, a few species accounted for the majority in numbers: four bird species for 95 % of the total of 23,000 seabirds recorded during 700 transect counts: fulmar Fulmarus glacialis, kittiwake Rissa tridactyla, Brünnich's guillemot Uria lomvia and little auk Alle alle. Among the marine mammals, 250 fin whales Balaenoptera physalus accounted for 80 % of the identified large cetaceans, 270 white-beaked dolphin Lagenorhynchus albirostris for 100 % of the small cetaceans and 180 harp seals Pagophilus groenlandica for 80 % of the identified pinnipeds. Their quantitative distribution was depending on water masses and oceanic fronts, large cetaceans-mainly fin whales-showing an important aggregation on the shelf slope off western Spitsbergen, as well as little auks and Brünnich's guillemots. So that this zone, shelf slope and front of mixed Arctic/Atlantic Waters, showed unusually high seabird and cetacean concentrations. Seasonal factors possibly influencing their distribution are addressed. [ABSTRACT FROM AUTHOR]

Morphological studies of the females of Calanus finmarchicus, C. glacialis, and C. hyperboreus were performed for specimens sampled in different areas of the Greenland, Barents, Kara, and Laptev seas. Intraspecific variability was found for the ratio of the specimens characterized by different types of setae patterns on the endopodites of C. glacialis and C. finmarchicus. The variability of this parameter did not relate to the environmental peculiarities of the sampling sites and did not depend on the temperature regime. We assume that such differences may be the result of the hybridization of C. glacialis and C. finmarchicus due to the similarity of their reproduction systems and the overlapping of the body size ranges. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examine satellite-derived chlorophyll, aerosol and sea ice in the Greenland Sea. [•] There is a moderate correlation between chlorophyll and aerosol in ice-free waters. [•] We find no correlation between chlorophyll and sea ice. [•] Peaks in aerosol during summer succeed the peak in chlorophyll. [•] Marine biogenic aerosol emissions influence the aerosol burden during summer. [Copyright &y& Elsevier]

We present an unprecedented multicentennial sediment record from the foot of Vesterisbanken Seamount, central Greenland Sea, covering the past 22.3 thousand years (ka). Based on planktic foraminiferal total abundances, species assemblages, and stable oxygen and carbon isotopes, the palaeoenvironments in this region of modern deepwater renewal were reconstructed. Results show that during the Last Glacial Maximum the area was affected by harsh polar conditions with only episodic improvements during warm summer seasons. Since 18 ka extreme freshwater discharges from nearby sources occurred, influencing the surface water environment. The last major freshwater event took place during the Younger Dryas. The onset of the Holocene was characterized by an improvement of environmental conditions suggesting warming and increasing ventilation of the upper water layers. The early Holocene saw a stronger Atlantic waters advection to the area, which began around 10.5 and ended quite rapidly at 5.5 ka, followed by the onset of Neoglacial cooling. Surface water ventilation reached a maximum in the middle Holocene. Around 3 ka the surface water stratification increased leading to subsequent amplification of the warming induced the North Atlantic Oscillation at 2 ka. [ABSTRACT FROM AUTHOR]

Highlights: [•] An aerial photographic survey for estimating the pup production of Greenland Sea hooded seals was carried out in 2012. [•] The obtained pup production estimate was 13,655 pups, giving an estimated total population of 84,020 seals in 2013. [•] The stock is below the conservation reference point in the precautionary harvest strategy developed by ICES for management of hooded seals. [•] Assuming no hunt the population model predicts a further decrease of the population size over the next 10 years. [•] Climate change with ice reductions, and subsequent increase in predation on pups, may have contributed to the low current stock level. [ABSTRACT FROM AUTHOR]

Swath-bathymetry data and 2D multichannel seismics reveal for the first time an up to ~60 km wide amphitheater-shaped slide scar on the eastern flank of the Jan Mayen Ridge, a micro-continent in the Norwegian-Greenland Sea. The scar opens southeastward where it continues as a narrower, topographically controlled translational area. It includes secondary scars, as well as channels and escarpments. Based on the identification of secondary scars, the slide is classified as a slide complex and the total volume of missing sediments was estimated at ~60 km. From the overall shape of the scar, the upslope widening from a bottleneck- or channel-like bypass-area, the failure is inferred to have had a retrogressive development. The absence of ridges, slabs and sediment blocks indicates that the failed sediments have been evacuated entirely. The smaller channels were formed from single or repetitive smaller flows post-dating the large failure events. [ABSTRACT FROM AUTHOR]

The fact that severe weather associated with polar lows and arctic fronts still comes unforeseen and puts human life at risk shows that an effort towards increased understanding of them is required. The observations of an arctic front by dropsondes and Doppler lidar carried onboard a research aircraft during the IPY-THORPEX field campaign offered a rare opportunity to investigate the mesoscale structure of the front and to validate the output from operational numerical weather prediction models. The observations revealed features similar to those of polar fronts such as a relatively steep frontal zone, the presence of a strong low-level jet and an elevated dry slot, making the arctic front appear as a shallow cold front confined to levels below 700 hPa. The dry slot indicated the presence of a downfolding of the tropopause, and together with the observations of an upper-level jet this strongly supports the inclusion of an arctic tropopause fold connected to the arctic jet stream in a conceptual model of the tropopause. A comparison between data from operational numerical weather prediction models and observations obtained during the flight shows that the models simulated the broad features of the frontal zone such as jets, dry slot and the depth of the front fairly well, although parts of the front were slightly misplaced. However, the models failed completely in their simulations of one of the three mesoscale cyclones associated with the front as they located it over the coast of northern Norway while the correct location was over the Greenland Sea according to the observations and analysis. [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]

Current estimates of global marine primary production range over a factor of two. Improving these estimates requires an accurate knowledge of the chlorophyll vertical profiles, since they are the basis for most primary production models. At high latitudes, the uncertainty in primary production estimates is larger than globally, because here phytoplankton absorption shows specific characteristics due to the low-light adaptation, and in situ data and ocean colour observations are scarce. To date, studies describing the typical chlorophyll profile based on the chlorophyll in the surface layer have not included the Arctic region, or, if it was included, the dependence of the profile shape on surface concentration was neglected. The goal of our study was to derive and describe the typical Greenland Sea chlorophyll profiles, categorized according to the chlorophyll concentration in the surface layer and further monthly resolved profiles. The Greenland Sea was chosen because it is known to be one of the most productive regions of the Arctic and is among the regions in the Arctic where most chlorophyll field data are available. Our database contained 1199 chlorophyll pro- files from R/Vs Polarstern and Maria S. Merian cruises combined with data from the ARCSS-PP database (Arctic primary production in situ database) for the years 1957-2010. The profiles were categorized according to their mean concentration in the surface layer, and then monthly median profiles within each category were calculated. The category with the surface layer chlorophyll (CHL) exceeding 0.7 mg Cm-3 showed values gradually decreasing from April to August. A similar seasonal pattern was observed when monthly profiles were averaged over all the surface CHL concentrations. The maxima of all chlorophyll profiles moved from the greater depths to the surface from spring to late summer respectively. The profiles with the smallest surface values always showed a subsurface chlorophyll maximum with its median magnitude reaching up to three times the surface concentration. While the variability of the Greenland Sea season in April, May and June followed the global non-monthly resolved relationship of the chlorophyll profile to surface chlorophyll concentrations described by the model of Morel and Berthon (1989), it deviated significantly from the model in the other months (July-September), when the maxima of the chlorophyll are at quite different depths. The Greenland Sea dimensionless monthly median profiles intersected roughly at one common depth within each category. By applying a Gaussian fit with 0.1 mg Cm-3 surface chlorophyll steps to the median monthly resolved chlorophyll profiles of the defined categories, mathematical approximations were determined. They generally reproduce the magnitude and position of the CHL maximum, resulting in an average 4% underestimation in Ctot (and 2% in rough primary production estimates) when compared to in situ estimates. These mathematical approximations can be used as the input to the satellite-based primary production models that estimate primary production in the Arctic regions. [ABSTRACT FROM AUTHOR]

The overflow of the dense water mass across the Greenland-Scotland Ridge (GSR) from the Nordic Seas drives the Atlantic meridional overturning circulation (AMOC). The Nordic Seas is a large basin with an enormous reservoir capacity. The volume of the dense water above the GSR sill depth in the Nordic Seas, according to previous estimates, is sufficient to supply decades of overflow transport. This large capacity buffers overflow's responses to atmospheric variations and prevents an abrupt shutdown of the AMOC. In this study, the authors use a numerical and an analytical model to show that the effective reservoir capacity of the Nordic Seas is actually much smaller than what was estimated previously. Basin-scale oceanic circulation is nearly geostrophic and its streamlines are basically the same as the isobaths. The vast majority of the dense water is stored inside closed geostrophic contours in the deep basin and thus is not freely available to the overflow. The positive wind stress curl in the Nordic Seas forces a convergence of the dense water toward the deep basin and makes the interior water even more removed from the overflow-feeding boundary current. Eddies generated by the baroclinic instability help transport the interior water mass to the boundary current. But in absence of a robust renewal of deep water, the boundary current weakens rapidly and the eddy-generating mechanism becomes less effective. This study indicates that the Nordic Seas has a relatively small capacity as a dense water reservoir and thus the overflow transport is sensitive to climate changes. [ABSTRACT FROM AUTHOR]

The biomass of Calanus spp. in the Norwegian Atlantic Current and the West Spitsbergen Current (2001–2009) was statistically related to a combination of salinity, temperature, water depth and sea ice concentration. The aim of this study was to identify the significance of these environmental factors for controlling the species-specific biomass distribution and the nature of such relationships. Calanus finmarchicus dominated the entire area and its biomass was mainly related to salinity. Calanus glacialis was mainly found along the northwest shelf of the Barents Sea, but its biomass was also related to the sea ice concentration and temperature with a critical threshold ∼6°C, above which the presence and biomass of C. glacialis decreased. The Calanus hyperboreus biomass was related to all environmental factors, which characterized by a confined spatial distribution to water associated with the Greenland Sea Gyre. We conclude that C. hyperboreus is an expatriate to the study area. The Calanus biomass distribution will not change greatly in the study area with an expected increase of water temperature by 2°C, whereas the critical temperature threshold for C. glacialis will be exceeded with temperature increases of ∼4°C with a likely disappearance of this cold water species from the north-west shelf of the Barents Sea. [ABSTRACT FROM AUTHOR]

SUMMARY In this contribution, we present a model of microcontinent architecture within a system that involves a complex rifted margin setting and different phases of deformation and continental breakup. Our case study is the Jan Mayen Microcontinent (JMMC) located in the central part of the Norwegian-Greenland Sea. We have revised its basement and sedimentary geometries using modern and vintage seismic reflection profiles, and updated potential field data. The northern part of the JMMC consists of a ∼10-15 km thick continental crust body flanked by two major sedimentary basins. We propose that the microcontinent is divided into six distinct segments, characterized by different basement and sedimentary architectures. The shallow stratigraphy is well imaged and has been detailed. Three distinct sedimentary units have been defined together with pronounced reflectors (JA, Red, JO and F), related to erosional, magmatic, thermal or uplift events. The continent-ocean boundary has been revised together with the mapping of the distinct volcanic events that characterize the evolution of the microcontinent. A companion paper aims to further detail the interpretation of the JMMC structure presented here by constraining the conjugated mid-Norwegian and mid-East Greenland structures. [ABSTRACT FROM AUTHOR]

SUMMARY We study the formation and evolution of the Jan Mayen microcontinent (JMMC) in the framework of conjugate margin evolution in the Norwegian-Greenland Sea. The JMMC structural map and crustal architecture have been constrained by seismic mapping and potential field modelling, supplemented by published seismic refraction transects. The sedimentary and basement geometries have been further studied together with their conjugate to refine our knowledge on the less explored microcontinent. Structurally, the JMMC main ridge is characterized by a platform and/or terrace architecture flanked by sag type basins, similar to those described on the mid-Norwegian conjugate margin, while its southern part is marked by windows exposing crustal and/or mantle material that was exhumed during higher degrees of extension. The eastern side of the JMMC broke up in a magma-rich fashion, while the western side is magma poor. The limited amount of magma involved in the JMMC formation suggests that changes in far field forces were the driving mechanism to initiate the isolation process and that a mantle plume had a lesser influence, but might have helped the final mid-ocean ridge establishment between the western Jan Mayen and Greenland margin. [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]

Current estimates of global marine primary production range over a factor of two. At high latitudes, the uncertainty is even larger than globally because here in-situ data and ocean color observations are scarce, and the phytoplankton absorption shows specific characteristics due to the low-light adaptation. The improvement of the primary production estimates requires an accurate knowledge on the chlorophyll vertical profile, which is the basis for most primary production models. To date, studies describing the typical chlorophyll profile based on the chlorophyll in the surface layer did not include the Arctic region or, if it was included, the dependence of the profile shape on surface concentration was neglected. The goal of our study was to derive and describe the typical Greenland Sea chlorophyll profiles, categorized according to the chlorophyll concentration in the surface layer and further monthly resolved. The Greenland Sea was chosen because it is known to be one of the most productive regions of the Arctic and is among the Arctic regions where most chlorophyll field data are available. Our database contained 1199 chlorophyll profiles from R/Vs Polarstern and Maria S Merian cruises combined with data of the ARCSS-PP database (Arctic primary production insitu database) for the years 1957-2010. The profiles were categorized according to their mean concentration in the surface layer and then monthly median profiles within each category were calculated. The category with the surface layer chlorophyll exceeding 0.7mgCm-3 showed a clear seasonal cycle with values gradually decreasing from April to August. Chlorophyll profiles maxima moved from lower depths in spring towards the surface in late summer. Profiles with smallest surface values always showed a subsurface chlorophyll maximum with its median magnitude reaching up to three times the surface concentration. While the variability in April, May and June of the Greenland Sea season is following the global non-monthly resolved relationship of the chlorophyll profile to surface chlorophyll concentrations described by the model of Morel and Berthon (1989), it deviates significantly from that in other months (July-September) where the maxima of the chlorophyll are at quite different depths. The Greenland Sea dimensionless monthly median profiles intersect roughly at one common depth within each category. Finally, by applying a Gaussian fitting with 0.1mgCm-3 surface chlorophyll steps to the median monthly resolved chlorophyll profiles of the defined categories, mathematical approximations have been determined. These will be used as the input to the satellite-based primary production models estimating primary production in Arctic regions [ABSTRACT FROM AUTHOR]

Abstract: We re-evaluate the structure and spreading evolution of the southeastern Norway Basin (NB) based on a new high resolution aeromagnetic survey (NB-07). The survey covers a complete oceanic spreading segment from the continental–oceanic transition of the Møre margin, off Norway to the aborted Aegir Ridge. The new survey documents a transform margin, an orthogonally rifted segment and an oblique-sheared volcanic margin formed during the onset of breakup, observed from the East Jan Mayen Fracture Zone to the Faroe Platform. The detailed fabric of the NB revealed by the new data indicates that two distinct tectonic phases have reshaped the basin before the cessation of seafloor spreading and abortion of the Aegir Ridge in the Late Oligocene. After continental breakup, Phase I (from C24 to C21r, ∼52 to 49 Ma) marks the earliest phase of spreading, probably initiated in the central and outer part of the Møre Basin. During this period, competing oceanic segments led to the formation of overlapping systems and pseudo-fault development. We observe a significant change in the NB''s oceanic spreading system in the late Early Eocene and, based on observations from surrounding areas, we suggest that this is a record of a major tectonic event in the Norwegian–Greenland Sea around C21r (49–47.9 Ma). During Phase II (from C21r to C10?, 48 to 28 Ma) of NB''s development, spreading rates decreased, spreading direction changed, and the number of faulting with large displacement increased leading to the formation of unexpected N–S oriented oceanic fracture zones. The fan-shaped development of the spreading system initiated around C21r (∼49–47.9 Ma) instead of C18–C17 (∼40–38 Ma) or C24 (53.3–52.3 Ma) as previously proposed. These new observations were used to re-evaluate the tectonic evolution of the Norwegian–Greenland Sea and discuss some implications on the syn- and post-breakup development of the surrounding continental margins and the evolution of the Jan Mayen microcontinent. [Copyright &y& Elsevier]

Abstract: The Ardencaple Canyon, emanating from the Eastern Greenland continental rise over a distance of about 200km towards the Greenland Basin, was investigated to determine the effect of enhanced down-slope transport mechanisms on deep-sea benthic prokaryotic communities. The concentration of viable bacterial cells (Live/Dead®BacLight) and prokaryotic incorporation rates (3H-thymidine, 14C-leucine) increased with increasing distance from the continental shelf. Multidimensional scaling (MDS) results from terminal restriction fragment length polymorphism (T-RFLP) analysis indicated a spatial coherence between the benthic bacterial community structure, prokaryotic incorporation rates, water content, protein concentration and the total organic matter in the sediments. The community complexity in sediments at 4–5cm depth was lower in the central parts of the channel compared with the northern and the southern levees, while richness in surface sediments of all stations was similar. Lacking any clear indications for a recent mass sediment transport or funneled shelf drainage flows, high similarities between bacterial assemblages in sediments along the canyon course may thus be governed by a combination of an ice-edge induced particle flux, episodic down-slope and canyon-guided transport mechanisms. [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 purpose of this study was to characterize for the first time seabird diving behavior during bimodal foraging. Little auks Alle alle, small zooplanktivorous Alcids of the High Arctic, have recently been shown to make foraging trips of short and long duration. Because short (ST) and long trips (LT) are thought to occur in different locations and serve different purposes (chick- and self-feeding, respectively) we hypothesized that foraging differences would be apparent, both in terms of water temperature and diving characteristics. Using Time Depth Recorders (TDRs), we tested this hypothesis at three colonies along the Greenland Sea with contrasting oceanographic conditions. We found that diving behavior generally differed between ST and LT. However, the magnitude of the disparity in diving characteristics depended on local foraging conditions. At the study site where conditions were favorable, diving behavior differed only to a small degree between LT and ST. Together with a lack of difference in diving depth and ocean temperature, this indicates that these birds did not increase their foraging effort during ST nor did they travel long distances to seek out more profitable prey. In contrast, where local foraging conditions were poor, birds increased their diving effort substantially to collect a chick meal during ST as indicated by longer, more U-shaped dives with slower ascent rates and shorter resting times (post-dive intervals and extended surface pauses). In addition, large differences in diving depth and ocean temperature indicate that birds forage on different prey species and utilize different foraging areas during LT, which may be up to 200 km away from the colony. Continued warming and deteriorating near-colony foraging conditions may have energetic consequences for little auks breeding in the eastern Greenland Sea. [ABSTRACT FROM AUTHOR]

We review the development of autonomous underwater vehicle (AUV) use under sea ice to map the three-dimensional (3-D) structure of the ice underside. The author, after extensive experience in under-ice profiling from submarines using single-beam sonar, carried out the first under-ice sidescan sonar profiling from an AUV in 2002 in the Greenland Sea. This was followed in August 2004 by the first full multibeam sonar experiment, using Kongsberg EM2000 sonar aboard the Autosub-II vehicle off NE Greenland. Two experiments using a small Gavia vehicle deployed through holes in the ice followed in 2007 and 2008, in the Beaufort Sea and off Ellesmere Island. Examples of the 3-D imagery are shown, and the two approaches of using a large vehicle deployed from a ship and a small through-ice vehicle are compared and found to be complementary. The imagery has shown that although first-year (FY) ridges have the familiar shape of a triangular prism made of small ice blocks, multi-year (MY) ridges are found to be broken up by lead formation into a chain of individual large ice blocks rather than a coherent linear feature. New work and future plans are described. [ABSTRACT FROM AUTHOR]

Seabirds are important components in marine ecosystems. However, knowledge of their ecology and spatial distribution during the non-breeding season is poor. More investigations during this critical period are required urgently, as marine environments are expected to be profoundly affected by climate change and human activities, with both direct and indirect consequences for marine top predators. Here, we studied the distribution of little auks ( Alle alle), one of the most abundant seabird species worldwide. We found that after the breeding season, birds from East Greenland quickly travelled north-east to stay for several weeks within a restricted area in the Greenland Sea. Activity patterns indicated that flying behaviour was much reduced during this period, suggesting that this is the primary moulting region for little auks. Birds then performed a southerly migration to overwinter off Newfoundland. These preliminary results provide important information for the conservation of this species and emphasise the need for further studies at a larger spatial scale. [ABSTRACT FROM AUTHOR]

ABSTRACT Annual air-sea exchange of CO2 in Young Sound, NE Greenland was estimated using pCO2 surface-water measurements during summer (2006-2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation, dissolved inorganic carbon (DIC) content is reduced causing sea ice to be under saturated in CO2. Approximately 1% of the DIC forced out of growing sea ice was released into the atmosphere while the remaining 99% was exported to the underlying water column. Sea ice covered the fjord 9 months a year and thereby efficiently blocked air-sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive carbonate minerals may contribute to the low surface-water pCO2 levels. The average annual uptake of atmospheric CO2 was estimated at 2.7 mol CO2 m−2 yr−1 or 32 g C m−2 yr−1 for the study area, which is lower than estimates from the Greenland Sea. Variability in duration of sea ice cover caused significant year-to-year variation in annual gas exchange. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effect of diverse oceanographic conditions and prey communities on the foraging behavior of little auks Alle alle in Greenland Sea. The study used time-depth recorders to compare the diving behavior and time allocation of little auks breeding adjacent to the East Greenland Current (EGC), the Sørkapp Current (SC), and West Spitsbergen Current (WSC). The study found that EGC is a favorable foraging environment than WSC and SC.

In the frame of our long-term study of the distribution of seabirds and marine mammals in polar seas, observers from this team participated in the European Arctic expeditions of icebreaking RV Polarstern during summer 2008. The main aims were to obtain more information on the mechanisms underlying the at-sea distribution of the 'higher trophic levels' and to detect possible temporal and spatial changes in numbers, especially in function of climatic changes and decreasing ice coverage in the Arctic. In total, 1,175 half-an-hour transect counts were devoted to seabird and marine mammal distribution in the Greenland and Norwegian Seas, from 14 June to 15 August, 2008. A major feeding ground for cetaceans and seabirds was detected in the south-western Greenland Sea and the Denmark Strait in the Polar Front between Polar and Arctic Water masses. For the main cetacean and seabird species, almost all individuals recorded during the whole expedition were encountered in this limited zone of 33 counts: 135 humpback whales Megaptera novaeangliae and 1,940 common guillemots Uria aalge. Moreover, 4,400 fulmars Fulmarus glacialis light morph were observed in this zone, i.e . close to half of the total. All were actively feeding, making this zone the major feeding ground for the higher trophic levels in the European Arctic Seas and so confirming the great importance of fronts (upwellings) for the biological productivity of the oceans. Such data are essential for a successful conservation and management of the Denmark Strait and adjacent areas. [ABSTRACT FROM AUTHOR]