WorldWideScience

Sample records for arctic ocean

  1. Arctic Ocean

    Science.gov (United States)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that tends to increase its sensitivity to climate change. Its temperature, salinity, and ice cover have all undergone changes in the past several decades, although it is uncertain whether these predominantly reflect long-term trends, oscillations within the system, or natural variability. Major changes include a warming and expansion of the Atlantic layer, at depths of 200-900 m, a warming of the upper ocean in the Beaufort Sea, a considerable thinning (perhaps as high as 40%) of the sea ice cover, a lesser and uneven retreat of the ice cover (averaging approximately 3% per decade), and a mixed pattern of salinity increases and decreases.

  2. Studying ocean acidification in the Arctic Ocean

    Science.gov (United States)

    Robbins, Lisa

    2012-01-01

    The U.S. Geological Survey (USGS) partnership with the U.S. Coast Guard Ice Breaker Healey and its United Nations Convention Law of the Sea (UNCLOS) cruises has produced new synoptic data from samples collected in the Arctic Ocean and insights into the patterns and extent of ocean acidification. This framework of foundational geochemical information will help inform our understanding of potential risks to Arctic resources due to ocean acidification.

  3. Ocean acidification in the Western Arctic Ocean

    Science.gov (United States)

    Cai, W.; Chen, B.; Chen, L.

    2011-12-01

    We report carbonate chemistry and ocean acidification status in the western Arctic Ocean from 65-88οN based on data collected in summer 2008 and 2010. In the marginal seas, surface waters have high pH and high carbonate saturation state (Ω) due to intensive biological uptake of CO2. In the southern Canada Basin, surface waters have low pH and low Ω due to the uptake of atmospheric CO2 and sea-ice melt. In the northern Arctic Ocean basin, there is no serious ocean acidification in surface water due to heavy ice-coverage but pH and Ω in the subsurface waters at the oxygen minimum and nutrient maximum zone (at 100-150 m) are low due mostly to respiration-derived CO2 and an increased biological production and export in surface waters. Such multitude responses of ocean carbonate chemistry (northern vs. southern basin, basins vs. margins, and surface vs. subsurface) to climate changes are unique to the Arctic Ocean system. We will explore biogeochemical control mechanisms on carbonate chemistry and ocean acidification in the Arctic Ocean environments in the context of recent warming and sea-ice retreat.

  4. Assembling an Arctic Ocean Boundary Monitoring Array

    OpenAIRE

    Tsubouchi, T.

    2014-01-01

    The Arctic Ocean boundary monitoring array has been maintained over many years by six research institutes located worldwide. Our approach to Arctic Ocean boundary measurements is generating significant scientific outcomes. However, it is not always easy to access Arctic data. On the basis of our last five years’ experience of assembling pan-Arctic boundary data, and considering the success of Argo, I propose that Arctic data policy should be driven by specific scientific-based requirements. O...

  5. Changing Arctic Ocean freshwater pathways.

    Science.gov (United States)

    Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike

    2012-01-04

    Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

  6. AMAP Assessment 2013: Arctic Ocean acidification

    Science.gov (United States)

    2013-01-01

    This assessment report presents the results of the 2013 AMAP Assessment of Arctic Ocean Acidification (AOA). This is the first such assessment dealing with AOA from an Arctic-wide perspective, and complements several assessments that AMAP has delivered over the past ten years concerning the effects of climate change on Arctic ecosystems and people. The Arctic Monitoring and Assessment Programme (AMAP) is a group working under the Arctic Council. The Arctic Council Ministers have requested AMAP to: - produce integrated assessment reports on the status and trends of the conditions of the Arctic ecosystems;

  7. Arctic and Southern Ocean Sea Ice Concentrations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly sea ice concentration for Arctic (1901 to 1995) and Southern oceans (1973 to 1990) were digitized on a standard 1-degree grid (cylindrical projection) to...

  8. International Regulation of Central Arctic Ocean Fisheries

    NARCIS (Netherlands)

    Molenaar, E.J.

    2016-01-01

    Due in particular to the impacts of climate change, the adequacy of the international regulation of Central Arctic Ocean fisheries has come under increasing scrutiny in recent years. As shown in this article, however, international regulation of Central Arctic Ocean fisheries is by no means entirely

  9. Rossby Waves in the Arctic Ocean

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Schmith, Torben

    The Arctic Ocean has a characteristic stable stratification with fresh and cold water occupying the upper few hundred meters and the warm and more saline Atlantic waters underneath. These water masses are separated by the cold halocline. The stability of the cold halocline regulates the upward...... directed turbulent heat flux from the Atlantic water to the Arctic water. This heat flux is a part of the arctic energy budget and is important for large scale sea ice formation and melting. Due to the strong vertical stratification combined with its almost circular boundary, the Arctic Ocean supports...

  10. Ice-Free Arctic Ocean?

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and researchers were unable to identify any natural processes that might slow the deicing of the Arctic. "What really makes the Arctic different…

  11. Arctic Ocean data in CARINA

    Directory of Open Access Journals (Sweden)

    S. Jutterström

    2010-02-01

    Full Text Available The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH, oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as applied adjustments.

  12. Arctic Ocean data in CARINA

    Directory of Open Access Journals (Sweden)

    S. Jutterström

    2009-08-01

    Full Text Available The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH, oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as suggested adjustments.

  13. Hydrochemical Atlas of the Arctic Ocean (NODC Accession 0044630)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The present Hydrochemical Atlas of the Arctic Ocean is a description of hydrochemical conditions in the Arctic Ocean on the basis of a greater body of hydrochemical...

  14. The great challenges in Arctic Ocean paleoceanography

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Ruediger, E-mail: Ruediger.Stein@awi.de [Alfred Wegener Institute for Polar and Marine Research, 27568 Bremerhaven (Germany)

    2011-05-15

    Despite the importance of the Arctic in the climate system, the data base we have from this area is still very weak, and large parts of the climate history have not been recovered at all in sedimentary sections. In order to fill this gap in knowledge, international, multidisciplinary expeditions and projects for scientific drilling/coring in the Arctic Ocean are needed. Key areas and approaches for drilling and recovering undisturbed and complete sedimentary sequences are depth transects across the major ocean ridge systems, i.e., the Lomonosov Ridge, the Alpha-Mendeleev Ridge, and the Chukchi Plateau/Northwind Ridge, the Beaufort, Kara and Laptev sea continental margins, as well as the major Arctic gateways towards the Atlantic and Pacific oceans. The new detailed climate records from the Arctic Ocean spanning time intervals from the Late Cretaceous/Paleogene Greenhouse world to the Neogene-Quaternary Icehouse world and representing short- and long-term climate variability on scales from 10 to 10{sup 6} years, will give new insights into our understanding of the Arctic Ocean within the global climate system and provide an opportunity to test the performance of climate models used to predict future climate change. With this, studying the Arctic Ocean is certainly one of the major challenges in climate research for the coming decades.

  15. SubArctic Oceans and Global Climate

    Science.gov (United States)

    Rhines, P. B.

    2004-12-01

    The passages connecting the Arctic Ocean with the Atlantic and Pacific, and their `mediterranean' basins, are focal points for the global meridional overturning circulation, and all of the climate impacts which this implies. It is also a difficult region to model accurately: the sensitivity of climate models to subpolar ocean dynamics is well-known. In this talk we stress the need to instrument and analyze the subpolar oceans, and some examples of sustained observations developing there. Results from satellite altimetry, recent Seaglider deployments from Greenland, and mooring arrays will be described. In particular we show the first Seaglider sections of hydrography and bio-optical profiles of the Labrador Sea (one of the first extended deployments of this autonomous undersea vehicle); we discuss the decline during the 1990s of the subpolar gyre circulation of the Atlantic from its great strength during the positive NAO period of the early 1990s, and its relevance to the salinity decline observed over a much longer period; we review observations of the flows at the Iceland-Scotland Ridge and Davis Strait, argued in terms of volume transport plots on the potential temperature/salinity plane; we display maps of the `convection resistance' (related to dynamic height) and its sensitivity to surface low-salinity water masses and their partition between shallow continental shelves and deep ocean. This is a particularly exciting time for climate studies, with fundamental properties of the atmosphere-ocean circulation under debate, even before one considers natural and human-induced variability. Is the four-decade long decline in subArctic salinity the result of increased hydrologic cycle, increased or altered Arctic outflow to the Atlantic, or slowing of the subpolar circulation? Is the basic intensity of the MOC more dependent on high-latitude buoyancy forcing, or wind- or tide-driven mixing in the upwelling branch, or possibly wind-stress at high latitude? Is the

  16. Mean Dynamic Topography of the Arctic Ocean

    Science.gov (United States)

    Farrell, Sinead Louise; Mcadoo, David C.; Laxon, Seymour W.; Zwally, H. Jay; Yi, Donghui; Ridout, Andy; Giles, Katherine

    2012-01-01

    ICESat and Envisat altimetry data provide measurements of the instantaneous sea surface height (SSH) across the Arctic Ocean, using lead and open water elevation within the sea ice pack. First, these data were used to derive two independent mean sea surface (MSS) models by stacking and averaging along-track SSH profiles gathered between 2003 and 2009. The ICESat and Envisat MSS data were combined to construct the high-resolution ICEn MSS. Second, we estimate the 5.5-year mean dynamic topography (MDT) of the Arctic Ocean by differencing the ICEn MSS with the new GOCO02S geoid model, derived from GRACE and GOCE gravity. Using these satellite-only data we map the major features of Arctic Ocean dynamical height that are consistent with in situ observations, including the topographical highs and lows of the Beaufort and Greenland Gyres, respectively. Smaller-scale MDT structures remain largely unresolved due to uncertainties in the geoid at short wavelengths.

  17. Arctic Ocean Scientific Drilling: The Next Frontier

    Directory of Open Access Journals (Sweden)

    Ruediger Stein

    2010-04-01

    Full Text Available The modern Arctic Ocean appears to be changing faster than any other region on Earth. To understand the potential extent of high latitude climate change, it is necessary to sample the history stored in the sediments filling the basins and covering the ridges of the Arctic Ocean. These sediments have been imaged with seismic reflection data, but except for the superficial record, which has been piston cored, they have been sampled only on the Lomonosov Ridge in 2004 during the Arctic Coring Expedition (ACEX-IODP Leg 302; Backman et al., 2006 and in 1993 in the ice-free waters in the Fram Strait/Yermak Plateau area (ODP Leg 151; Thiede et al., 1996.Although major progress in Arctic Ocean research has been made during the last few decades, the short- and long-term paleoceanographic and paleoclimatic history as well as its plate-tectonic evolution are poorly known compared to the other oceans. Despite the importance of the Arctic in the climate system, the database we have from this area is still very weak. Large segments of geologic time have not been sampled in sedimentary sections. The question of regional variations cannot be addressed.

  18. The Arctic Ocean's seasonal cycle must change

    Science.gov (United States)

    Carton, James; Ding, Yanni

    2015-04-01

    This paper discusses anticipated changes to the seasonal cycle of the Arctic Ocean along with Arctic surface climate due to the reduction of seasonal sea ice cover expected in the 21st century. Net surface shortwave radiation is a function of surface reflectivity and atmospheric transparency as well as solar declination. Recent observational studies and modeling results presented here strongly suggest that this excess heat in the summer is currently being stored locally in the form of ocean warming and sea ice melt. This heat is lost in winter/spring through surface loss through longwave and turbulent processes causing ocean cooling and the refreezing of sea ice. A striking feature of Arctic climate during the 20th century has been the enhanced warming experienced during winter in response to increases in anthropogenic greenhouse gasses. The amplitude of the seasonal cycle of surface air temperature is declining by gradually warming winter temperatures relative to summer temperatures. Bintanja and van der Linden (2013) show this process will eventually cause the 30C seasonal change in air temperature to reduce by half as seasonal sea ice disappears. The much weaker seasonal cycle of ocean temperature, which is controlled by the need to store excess surface heat seasonally, is also going to be affected by the loss of sea ice but in quite different ways. In particular the ocean will need to compensate for the loss of seasonal heat storage by the ice pack. This study examines consequences for the Arctic Ocean stratification and circulation in a suite of CMIP5 models under future emissions scenarios relative to their performance during the 20th century and to explore a range of model ocean responses to declining sea ice cover on the Arctic Ocean.

  19. The Arctic Ocean Perennial Ice Zone

    Science.gov (United States)

    Kwok, R.; Cunningham, G. F.; Yueh, S.

    1998-01-01

    This study shows that: 1) the NSCAT backscatter fields provide an estimate of the PIZ coverage of the Arctic Ocean; and, 2) the decrease in PIZ area over the winter gives an indication of the PIZ area exported through Fram Strait.

  20. The phenology of Arctic Ocean surface warming

    Science.gov (United States)

    Steele, Michael; Dickinson, Suzanne

    2016-09-01

    In this work, we explore the seasonal relationships (i.e., the phenology) between sea ice retreat, sea surface temperature (SST), and atmospheric heat fluxes in the Pacific Sector of the Arctic Ocean, using satellite and reanalysis data. We find that where ice retreats early in most years, maximum summertime SSTs are usually warmer, relative to areas with later retreat. For any particular year, we find that anomalously early ice retreat generally leads to anomalously warm SSTs. However, this relationship is weak in the Chukchi Sea, where ocean advection plays a large role. It is also weak where retreat in a particular year happens earlier than usual, but still relatively late in the season, primarily because atmospheric heat fluxes are weak at that time. This result helps to explain the very different ocean warming responses found in two recent years with extreme ice retreat, 2007 and 2012. We also find that the timing of ice retreat impacts the date of maximum SST, owing to a change in the ocean surface buoyancy and momentum forcing that occurs in early August that we term the Late Summer Transition (LST). After the LST, enhanced mixing of the upper ocean leads to cooling of the ocean surface even while atmospheric heat fluxes are still weakly downward. Our results indicate that in the near-term, earlier ice retreat is likely to cause enhanced ocean surface warming in much of the Arctic Ocean, although not where ice retreat still occurs late in the season.

  1. Ocean surface waves in an ice-free Arctic Ocean

    Science.gov (United States)

    Li, Jian-Guo

    2016-08-01

    The retreat of the Arctic ice edge implies that global ocean surface wave models have to be extended at high latitudes or even to cover the North Pole in the future. The obstacles for conventional latitude-longitude grid wave models to cover the whole Arctic are the polar problems associated with their Eulerian advection schemes, including the Courant-Friedrichs-Lewy (CFL) restriction on diminishing grid length towards the Pole, the singularity at the Pole and the invalid scalar assumption for vector components defined relative to the local east direction. A spherical multiple-cell (SMC) grid is designed to solve these problems. It relaxes the CFL restriction by merging the longitudinal cells towards the Poles. A round polar cell is used to remove the singularity of the differential equation at the Pole. A fixed reference direction is introduced to define vector components within a limited Arctic part in mitigation of the scalar assumption errors at high latitudes. The SMC grid has been implemented in the WAVEWATCH III model and validated with altimeter and buoy observations, except for the Arctic part, which could not be fully tested due to a lack of observations as the polar region is still covered by sea ice. Here, an idealised ice-free Arctic case is used to test the Arctic part and it is compared with a reference case with real ice coverage. The comparison indicates that swell wave energy will increase near the ice-free Arctic coastlines due to increased fetch. An expanded Arctic part is used for comparisons of the Arctic part with available satellite measurements. It also provides a direct model comparison between the two reference systems in their overlapping zone.

  2. Global View of the Arctic Ocean

    Science.gov (United States)

    2000-01-01

    NASA researchers have new insights into the mysteries of Arctic sea ice, thanks to the unique abilities of Canada's Radarsat satellite. The Arctic is the smallest of the world's four oceans, but it may play a large role in helping scientists monitor Earth's climate shifts.Using Radarsat's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic. This allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter. The radar-generated, high-resolution images are up to 100 times better than those taken by previous satellites.Using this new information, scientists at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., can generate comprehensive maps of Arctic sea ice thickness for the first time. 'Before we knew only the extent of the ice cover,' said Dr. Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness Derived From High Resolution Radar Imagery. 'We also knew that the sea ice extent had decreased over the last 20 years, but we knew very little about ice thickness.''Since sea ice is very thin, about 3 meters (10 feet) or less,'Kwok explained, 'it is very sensitive to climate change.'Until now, observations of polar sea ice thickness have been available for specific areas, but not for the entire polar region.The new radar mapping technique has also given scientists a close look at how the sea ice cover grows and contorts over time. 'Using this new data set, we have the first estimates of how much ice has been produced and where it formed during the winter. We have never been able to do this before, ' said Kwok. 'Through our radar maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice growth in the new openings. 'RADARSAT gives researchers a piece of the overall puzzle every three days by creating a complete image of the Arctic. NASA scientists then put those puzzle pieces together to create a time

  3. Increase in acidifying water in the western Arctic Ocean

    Science.gov (United States)

    Qi, Di; Chen, Liqi; Chen, Baoshan; Gao, Zhongyong; Zhong, Wenli; Feely, Richard A.; Anderson, Leif G.; Sun, Heng; Chen, Jianfang; Chen, Min; Zhan, Liyang; Zhang, Yuanhui; Cai, Wei-Jun

    2017-02-01

    The uptake of anthropogenic CO2 by the ocean decreases seawater pH and carbonate mineral aragonite saturation state (Ωarag), a process known as Ocean Acidification (OA). This can be detrimental to marine organisms and ecosystems. The Arctic Ocean is particularly sensitive to climate change and aragonite is expected to become undersaturated (Ωarag oceans. However, the extent and expansion rate of OA in this region are still unknown. Here we show that, between the 1990s and 2010, low Ωarag waters have expanded northwards at least 5°, to 85° N, and deepened 100 m, to 250 m depth. Data from trans-western Arctic Ocean cruises show that Ωarag Arctic Ocean than the Pacific and Atlantic oceans, with the western Arctic Ocean the first open-ocean region with large-scale expansion of `acidified’ water directly observed in the upper water column.

  4. Arctic Ocean Regional Climatology Online Atlas (NODC Accession 0115771)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To provide an improved oceanographic foundation and reference for multi-disciplinary studies of the Arctic Ocean, NODC developed a new set of high-resolution...

  5. Diurnal tides in the Arctic Ocean

    Science.gov (United States)

    Kowalik, Z.; Proshutinsky, A. Y.

    1993-01-01

    A 2D numerical model with a space grid of about 14 km is applied to calculate diurnal tidal constituents K(1) and O(1) in the Arctic Ocean. Calculated corange and cotidal charts show that along the continental slope, local regions of increased sea level amplitude, highly variable phase and enhanced currents occur. It is shown that in these local regions, shelf waves (topographic waves) of tidal origin are generated. In the Arctic Ocean and Northern Atlantic Ocean more than 30 regions of enhanced currents are identified. To prove the near-resonant interaction of the diurnal tides with the local bottom topography, the natural periods of oscillations for all regions have been calculated. The flux of energy averaged over the tidal period depicts the gyres of semitrapped energy, suggesting that the shelf waves are partially trapped over the irregularities of the bottom topography. It is shown that the occurrence of near-resonance phenomenon changes the energy flow in the tidal waves. First, the flux of energy from the astronomical sources is amplified in the shelf wave regions, and afterwards the tidal energy is strongly dissipated in the same regions.

  6. What Should Children Know about the Arctic Ocean?

    Science.gov (United States)

    Stockard, James W., Jr.

    1989-01-01

    Lists essential information about the Arctic Ocean which should be taught in elementary social studies courses, and which teacher training programs should cover. Discusses popular misconceptions regarding the Arctic Ocean and factors, such as the coloration on maps and globes, which lead to these misconceptions. (LS)

  7. Consequences of future increased Arctic runoff on Arctic Ocean stratification, circulation, and sea ice cover

    Science.gov (United States)

    Nummelin, Aleksi; Ilicak, Mehmet; Li, Camille; Smedsrud, Lars H.

    2016-01-01

    The Arctic Ocean has important freshwater sources including river runoff, low evaporation, and exchange with the Pacific Ocean. In the future, we expect even larger freshwater input as the global hydrological cycle accelerates, increasing high-latitude precipitation, and river runoff. Previous modeling studies show some robust responses to high-latitude freshwater perturbations, including a strengthening of Arctic stratification and a weakening of the large-scale ocean circulation; some idealized modeling studies also document a stronger cyclonic circulation within the Arctic Ocean itself. With the broad range of scales and processes involved, the overall effect of increasing runoff requires an understanding of both the local processes and the broader linkages between the Arctic and surrounding oceans. Here we adopt a more comprehensive modeling approach by increasing river runoff to the Arctic Ocean in a coupled ice-ocean general circulation model, and show contrasting responses in the polar and subpolar regions. Within the Arctic, the stratification strengthens, the halocline and Atlantic Water layer warm, and the cyclonic circulation spins up, in agreement with previous work. In the subpolar North Atlantic, the model simulates a colder and fresher water column with weaker barotropic circulation. In contrast to the estuarine circulation theory, the volume exchange between the Arctic Ocean and the surrounding oceans does not increase with increasing runoff. While these results are robust in our model, we require experiments with other model systems and more complete observational syntheses to better constrain the sensitivity of the climate system to high-latitude freshwater perturbations.

  8. Fresh Water Content Variability in the Arctic Ocean

    Science.gov (United States)

    Hakkinen, Sirpa; Proshutinsky, Andrey

    2003-01-01

    Arctic Ocean model simulations have revealed that the Arctic Ocean has a basin wide oscillation with cyclonic and anticyclonic circulation anomalies (Arctic Ocean Oscillation; AOO) which has a prominent decadal variability. This study explores how the simulated AOO affects the Arctic Ocean stratification and its relationship to the sea ice cover variations. The simulation uses the Princeton Ocean Model coupled to sea ice. The surface forcing is based on NCEP-NCAR Reanalysis and its climatology, of which the latter is used to force the model spin-up phase. Our focus is to investigate the competition between ocean dynamics and ice formation/melt on the Arctic basin-wide fresh water balance. We find that changes in the Atlantic water inflow can explain almost all of the simulated fresh water anomalies in the main Arctic basin. The Atlantic water inflow anomalies are an essential part of AOO, which is the wind driven barotropic response to the Arctic Oscillation (AO). The baroclinic response to AO, such as Ekman pumping in the Beaufort Gyre, and ice meldfreeze anomalies in response to AO are less significant considering the whole Arctic fresh water balance.

  9. On the atmospheric response experiment to a Blue Arctic Ocean

    Science.gov (United States)

    Nakamura, Tetsu; Yamazaki, Koji; Honda, Meiji; Ukita, Jinro; Jaiser, Ralf; Handorf, Dörthe; Dethloff, Klaus

    2016-10-01

    We demonstrated atmospheric responses to a reduction in Arctic sea ice via simulations in which Arctic sea ice decreased stepwise from the present-day range to an ice-free range. In all cases, the tropospheric response exhibited a negative Arctic Oscillation (AO)-like pattern. An intensification of the climatological planetary-scale wave due to the present-day sea ice reduction on the Atlantic side of the Arctic Ocean induced stratospheric polar vortex weakening and the subsequent negative AO. Conversely, strong Arctic warming due to ice-free conditions across the entire Arctic Ocean induced a weakening of the tropospheric westerlies corresponding to a negative AO without troposphere-stratosphere coupling, for which the planetary-scale wave response to a surface heat source extending to the Pacific side of the Arctic Ocean was responsible. Because the resultant negative AO-like response was accompanied by secondary circulation in the meridional plane, atmospheric heat transport into the Arctic increased, accelerating the Arctic amplification.

  10. Arctic Ocean shelf biogeochemical cycling under climate change

    Science.gov (United States)

    Bellerby, Richard; Silyakova, Anna; Slagstad, Dag

    2014-05-01

    Changes to Arctic Ocean biogeochemistry will result from a complex array of climate and chemical perturbations over the next decades. Changes to freshwater and nutrient supply through ice melt and continental runoff; warming of the ocean and an increasing ocean acidification through partial equilibrium with a rising anthropogenic CO2 load will change the nature of Arctic Ocean ecological and biogeochemical coupling. This is no more apparent on the shelf regions where there is strong influence from land sources of freshwater and total alkalinity. This presentation will document our combined approach of studying Arctic biogeochemical change through coupled observational, experimental and modelling campaigns. We have identified large changes in recent anthropogenic carbon transport to the Arctic and have characterised the associated regional and water mass ocean acidification. We have determined, through targeted Arctic pelagic ecosystem perturbations experiments, changes to ecosystem structure, succession and biogeochemical cycling under high CO2. Observations have been incorporated into regional, coupled physical-ecosystem-carbon biogeochemical models (informed at the boundaries by downscaled global earth system models) to develop scenarios of change in biogeochemical pathways. We have identified large regional variability in ocean acidification that is shown to impact on shelf biogeochemistry, ecosystems and climate feedbacks in the Arctic Ocean.

  11. USGS Arctic Ocean Carbon Cruise 2011: Discrete Lab data

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Models project the Arctic Ocean will become undersaturated with respect to carbonate minerals in the next decade. Recent field results indicate parts may already be...

  12. USGS Arctic Ocean Carbon Cruise 2010: Discrete Lab data

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Models project the Arctic Ocean will become undersaturated with respect to carbonate minerals in the next decade. Recent field results indicate parts may already be...

  13. USGS Arctic Ocean Carbon Cruise 2011: Discrete Underway data

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Models project the Arctic Ocean will become undersaturated with respect to carbonate minerals in the next decade. Recent field results indicate parts may already be...

  14. USGS Arctic Ocean Carbon Cruise 2012: Discrete Underway Laboratory data

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Models project the Arctic Ocean will become undersaturated with respect to carbonate minerals in the next decade. Recent field results indicate parts may already be...

  15. Late Cretaceous seasonal ocean variability from the Arctic.

    Science.gov (United States)

    Davies, Andrew; Kemp, Alan E S; Pike, Jennifer

    2009-07-09

    The modern Arctic Ocean is regarded as a barometer of global change and amplifier of global warming and therefore records of past Arctic change are critical for palaeoclimate reconstruction. Little is known of the state of the Arctic Ocean in the greenhouse period of the Late Cretaceous epoch (65-99 million years ago), yet records from such times may yield important clues to Arctic Ocean behaviour in near-future warmer climates. Here we present a seasonally resolved Cretaceous sedimentary record from the Alpha ridge of the Arctic Ocean. This palaeo-sediment trap provides new insight into the workings of the Cretaceous marine biological carbon pump. Seasonal primary production was dominated by diatom algae but was not related to upwelling as was previously hypothesized. Rather, production occurred within a stratified water column, involving specially adapted species in blooms resembling those of the modern North Pacific subtropical gyre, or those indicated for the Mediterranean sapropels. With increased CO(2) levels and warming currently driving increased stratification in the global ocean, this style of production that is adapted to stratification may become more widespread. Our evidence for seasonal diatom production and flux testify to an ice-free summer, but thin accumulations of terrigenous sediment within the diatom ooze are consistent with the presence of intermittent sea ice in the winter, supporting a wide body of evidence for low temperatures in the Late Cretaceous Arctic Ocean, rather than recent suggestions of a 15 degrees C mean annual temperature at this time.

  16. Late Cenozoic Paleoceanography of the Central Arctic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    O' Regan, Matt, E-mail: oreganM1@cardiff.ac.uk [School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, Wales (United Kingdom)

    2011-05-15

    The Arctic Ocean is the smallest and perhaps least accessible of the worlds oceans. It occupies only 26% of the global ocean area, and less than 10% of its volume. However, it exerts a disproportionately large influence on the global climate system through a complex set of positive and negative feedback mechanisms directly or indirectly related to terrestrial ice and snow cover and sea ice. Increasingly, the northern high latitude cryosphere is seen as an exceptionally fragile part of the global climate system, a fact exemplified by observed reductions in sea ice extent during the past decades [2]. The paleoceanographic evolution of the Arctic Ocean can provide important insights into the physical forcing mechanisms that affect the form, intensity and permanence of ice in the high Arctic, and its sensitivity to these mechanisms in vastly different climate states of the past. However, marine records capturing the late Cenozoic paleoceanography of the Arctic are limited - most notably because only a single deep borehole exists from the central parts of this Ocean. This paper reviews the principal late Cenozoic (Neogene/Quaternary) results from the Arctic Coring Expedition to the Lomonosov Ridge and in light of recent data and observations on modern sea ice, outlines emerging questions related to three main themes: 1) the establishment of the 'modern' Arctic Ocean and the opening of the Fram Strait 2) the inception of perennial sea ice 3) The Quaternary intensification of Northern Hemisphere glaciations.

  17. The Arctic Ocean in the global climate system (review)

    OpenAIRE

    Alekseev,G. V./Ivanov,V. V./Zakharov,V. F./Yanes,A. V.

    1996-01-01

    The oceanic portion of the Arctic climate system has a strong influence on global climate change. This is because, first, the Arctic Ocean can change its capacity for redistribution of solar heat in consequence of the changes of thermohaline structure of the upper layer and the sea ice area on its surface, second; the vertical oceanic circulation in high latitudes is very sensitive to changes of the fresh water balance on the ocean surface that can cause a profound effect on the production of...

  18. Deep Arctic Ocean warming during the last glacial cycle

    Science.gov (United States)

    Cronin, T. M.; Dwyer, G.S.; Farmer, J.; Bauch, H.A.; Spielhagen, R.F.; Jakobsson, M.; Nilsson, J.; Briggs, W.M.; Stepanova, A.

    2012-01-01

    In the Arctic Ocean, the cold and relatively fresh water beneath the sea ice is separated from the underlying warmer and saltier Atlantic Layer by a halocline. Ongoing sea ice loss and warming in the Arctic Ocean have demonstrated the instability of the halocline, with implications for further sea ice loss. The stability of the halocline through past climate variations is unclear. Here we estimate intermediate water temperatures over the past 50,000 years from the Mg/Ca and Sr/Ca values of ostracods from 31 Arctic sediment cores. From about 50 to 11 kyr ago, the central Arctic Basin from 1,000 to 2,500 m was occupied by a water mass we call Glacial Arctic Intermediate Water. This water mass was 1–2 °C warmer than modern Arctic Intermediate Water, with temperatures peaking during or just before millennial-scale Heinrich cold events and the Younger Dryas cold interval. We use numerical modelling to show that the intermediate depth warming could result from the expected decrease in the flux of fresh water to the Arctic Ocean during glacial conditions, which would cause the halocline to deepen and push the warm Atlantic Layer into intermediate depths. Although not modelled, the reduced formation of cold, deep waters due to the exposure of the Arctic continental shelf could also contribute to the intermediate depth warming.

  19. US Navy Operational Global Ocean and Arctic Ice Prediction Systems

    Science.gov (United States)

    2014-09-01

    Arctic ice prediction systems. Oceanography 27(3):32–43, http://dx.doi.org/10.5670/oceanog.2014.66. DOI http://dx.doi.org/10.5670/oceanog.2014.66...P E C I A L I S S U E O N N AV Y O P E R AT I O N A L M O D E L S US Navy Operational Global Ocean and Arctic Ice Prediction Systems B Y E...and forecasting of oceanic “ weather ,” including three dimensional (3D) ocean temperature, salinity, and current structure; surface mixed layer

  20. A new high resolution tidal model in the arctic ocean

    DEFF Research Database (Denmark)

    Cancet, M.; Andersen, Ole Baltazar; Lyard, F.

    The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence......-growing maritime and industrial activities in this region. NOVELTIS and DTU Space have developed a regional, high-resolution tidal atlas in the Arctic Ocean, in the framework of the CryoSat Plus for Ocean (CP4O) ESA project. In particular, this atlas benefits from the assimilation of the most complete satellite...... for assimilation and validation. This paper presents the performances of this new regional tidal model in the Arctic Ocean, compared to the existing global tidal models....

  1. Pliocene palaeoceanography of the Arctic Ocean and subarctic seas.

    Science.gov (United States)

    Matthiessen, Jens; Knies, Jochen; Vogt, Christoph; Stein, Ruediger

    2009-01-13

    The Pliocene is important in the geological evolution of the high northern latitudes. It marks the transition from restricted local- to extensive regional-scale glaciations on the circum-Arctic continents between 3.6 and 2.4Ma. Since the Arctic Ocean is an almost land-locked basin, tectonic activity and sea-level fluctuations controlled the geometry of ocean gateways and continental drainage systems, and exerted a major influence on the formation of continental ice sheets, the distribution of river run-off, and the circulation and water mass characteristics in the Arctic Ocean. The effect of a water mass exchange restricted to the Bering and Fram Straits on the oceanography is unknown, but modelling experiments suggest that this must have influenced the Atlantic meridional overturning circulation. Cold conditions associated with perennial sea-ice cover might have prevailed in the central Arctic Ocean throughout the Pliocene, whereas colder periods alternated with warmer seasonally ice-free periods in the marginal areas. The most pronounced oceanographic change occurred in the Mid-Pliocene when the circulation through the Bering Strait reversed and low-salinity waters increasingly flowed from the North Pacific into the Arctic Ocean. The excess freshwater supply might have facilitated sea-ice formation and contributed to a decrease in the Atlantic overturning circulation.

  2. Hydrography shapes bacterial biogeography of the deep Arctic Ocean.

    Science.gov (United States)

    Galand, Pierre E; Potvin, Marianne; Casamayor, Emilio O; Lovejoy, Connie

    2010-04-01

    It has been long debated as to whether marine microorganisms have a ubiquitous distribution or patterns of biogeography, but recently a consensus for the existence of microbial biogeography is emerging. However, the factors controlling the distribution of marine bacteria remain poorly understood. In this study, we combine pyrosequencing and traditional Sanger sequencing of the 16S rRNA gene to describe in detail bacterial communities from the deep Arctic Ocean. We targeted three separate water masses, from three oceanic basins and show that bacteria in the Arctic Ocean have a biogeography. The biogeographical distribution of bacteria was explained by the hydrography of the Arctic Ocean and subsequent circulation of its water masses. Overall, this first taxonomic description of deep Arctic bacteria communities revealed an abundant presence of SAR11 (Alphaproteobacteria), SAR406, SAR202 (Chloroflexi) and SAR324 (Deltaproteobacteria) clusters. Within each cluster, the abundance of specific phylotypes significantly varied among water masses. Water masses probably act as physical barriers limiting the dispersal and controlling the diversity of bacteria in the ocean. Consequently, marine microbial biogeography involves more than geographical distances, as it is also dynamically associated with oceanic processes. Our ocean scale study suggests that it is essential to consider the coupling between microbial and physical oceanography to fully understand the diversity and function of marine microbes.

  3. Internal modes of multidecadal variability in the Arctic Ocean

    OpenAIRE

    L. M. Frankcombe; H. A. Dijkstra

    2010-01-01

    Observations of sea ice extent and atmospheric temperature in the Arctic, although sparse, indicate variability on multidecadal time scales. A recent analysis of one of the global climate models [the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (CM2.1)] in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change has indicated that Arctic Ocean variability on these time scales is associated with changes in basin-wide salinity patterns. In this pap...

  4. Modern benthic foraminifer distribution in the Amerasian Basin, Arctic Ocean

    Science.gov (United States)

    Ishman, S.E.; Foley, K.M.

    1996-01-01

    A total of 38 box cores were collected from the Amerasian Basin, Arctic Ocean during the U.S. Geological Survey 1992 (PI92-AR) and 1993 (PI93-AR) Arctic Cruises aboard the U.S. Coast Guard Icebreaker Polar Star. In addition, the cruises collected geophysical data, piston cores and hydrographic data to address the geologic and oceanographic history of the western Arctic Ocean. This paper reports the results of the quantitative analyses of benthic foraminifer distribution data of the total (live + dead) assemblages derived from 22 box core-top samples. The results show that a distinct depth distribution of three dominant benthic foraminifer assemblages, the Textularia spp. - Spiroplectammina biformis, Cassidulina teretis and Oridorsalis tener - Eponides tumidulus Biofacies are strongly controlled by the dominant water masses within the Canada Basin: the Arctic Surface Water, Arctic Intermediate Water and Canada Basin Deep Water. The faunal distributions and their oceanographic associations in the Canada Basin are consistent with observations of benthic foraminifer distributions from other regions within the Arctic Ocean.

  5. The Arctic Ocean: opportunities of a new maritime boundary

    Directory of Open Access Journals (Sweden)

    Marcos Valle Machado da Silva

    2014-07-01

    Full Text Available Climate change due to global warming will not only have negative effects. In the case of maritime trade, the risk arising from the increase in the average temperature of the planet has some opportunities already being analyzed by various states. One such opportunity relates to the potential use of sea routes through the Arctic, linking the Pacific and Atlantic oceans. The purpose of this article is to analyze the implications for maritime trade, resulting from the reduction of the ice cover in the Arctic Ocean and to show which states are shaping the institutions and rules for use of this new opportunity. To achieve this goal, the text was divided into three sections. The first introduces the reader to the projections accessibility to navigation in the Arctic Ocean and the potential shipping routes that are revealed for the maritime trade. The second section of the paper examines how states with territory in the Arctic, as well as those with direct interests in the region, are articulating institutions for this purpose, notably the Arctic Council. The third and final section examines "how" and "why" China, a State exogenous to the Arctic, has managed to implement successful strategies in defense of their interests in the region.

  6. Anthropogenic radionuclides in the Arctic Ocean. Distribution and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Josefsson, Dan

    1998-05-01

    Anthropogenic radionuclide concentrations have been determined in seawater and sediment samples collected in 1991, 1994 and 1996 in the Eurasian Arctic shelf and interior. Global fallout, releases from European reprocessing plants and the Chernobyl accident are identified as the three main sources. From measurements in the Eurasian shelf seas it is concluded that the total input of {sup 134}Cs, {sup 137}Cs and {sup 90}Sr from these sources has been decreasing during the 1990`s, while {sup 129}I has increased. The main fraction of the reprocessing and Chernobyl activity found in Arctic Ocean surface layer is transported from the Barents Sea east along the Eurasian Arctic shelf seas to the Laptev Sea before entering the Nansen Basin. This inflow results in highest {sup 137}Cs, {sup 129}I and {sup 90}Sr concentrations in the Arctic Ocean surface layers, and continuously decreasing concentrations with depth. Chernobyl-derived {sup 137}Cs appeared in the central parts of the Arctic Ocean around 1991, and in the mid 1990`s the fraction to total {sup 137}Cs was approximately 30% in the entire Eurasian Arctic region. The transfer times for releases from Sellafield are estimated to be 5-7 years to the SE Barents Sea, 7-9 years to the Kara Sea, 10-11 years to the Laptev Sea and 12-14 years to the central Arctic Ocean. Global fallout is the primary source of plutonium with highest concentrations found in the Atlantic layer of the Arctic Ocean. When transported over the shallow shelf seas, particle reactive transuranic elements experience an intense scavenging. A rough estimate shows that approximately 75% of the plutonium entering the Kara and Laptev Seas are removed to the sediment. High seasonal riverine input of {sup 239}, {sup 240}Pu is observed near the mouths of the large Russian rivers. Sediment inventories show much higher concentrations on the shelf compared to the deep Arctic Ocean. This is primarily due to the low particle flux in the open ocean

  7. Nordic Seas and Arctic Ocean CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    E. Jeansson

    2009-10-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. The Arctic Mediterranean Seas is comprised of the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas.

    Here we present an overview of the QC of the CFC data for the Arctic Mediterranean Seas, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113, as well as carbon tetrachloride (CCl4. For the secondary QC of the CFCs we used a combination of tools, including the evaluation of depth profiles and CFC ratios, surface saturations and a crossover analysis. This resulted in a multiplicative adjustment of some cruise data, while some other cruises were flagged with questionable quality, which excluded them from the final data product.

  8. Physical constrains and productivity in the future Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Dag eSlagstad

    2015-10-01

    Full Text Available Todays physical oceanography and primary and secondary production was investigated for the entire Arctic Ocean with the physical-biologically coupled SINMOD model. To obtain indications on the effect of climate change in the 21th century the magnitude of change, and where and when these may take place SINMOD was forced with down-scaled climate trajectories of the International Panel of Climate Change with the A1B climate scenario which appears to predict an average global atmospheric temperature increase of 3.5 to 4 °C at the end of this century. It is projected that some surface water features of the physical oceanography in the Arctic Ocean and adjacent regions will change considerably. The largest changes will occur along the continuous domains of Pacific and in particular regarding Atlantic Water advection and the inflow shelves. Withdrawal of ice will increase primary production, but stratification will persist or, for the most, get stronger as a function of ice-melt and thermal warming along the inflow shelves. Thus the nutrient dependent new and harvestable production will not increase proportionally with increasing photosynthetic active radiation. The greatest increases in primary production are found along the Eurasian perimeter of the Arctic Ocean (up to 40 g C m-2 y-1 and in particular in the northern Barents and Kara Seas (40-80 g C m-2 y-1 where less ice-cover implies less Arctic Water and thus less stratification. Along the shelf break engirdling the Arctic Ocean upwelling and vertical mixing supplies nutrients to the euphotic zone when ice-cover withdraws northwards. The production of Arctic copepods along the Eurasian perimeter of the Arctic Ocean will increase significantly by the end of this century (2-4 g C m-2 y-1. Primary and secondary production will decrease along the southern sections of the continuous advection domains of Pacific and Atlantic Water due to increasing thermal stratification. In the central Arctic Ocean

  9. An Arctic Ice/Ocean Coupled Model with Wave Interactions

    Science.gov (United States)

    2015-09-30

    including the influential contribution that ocean waves make in reshaping the Arctic ice -covered ocean. In a nutshell, waves break up the sea ice ...feedback by bringing warmer water in contact with the decaying ice mass. In tandem, aggregated fetch length may be increased because of the incidence of...inhomogeneous ice cover as a surface-floating viscoelastic layer or viscoelastic beam which consolidates the physical properties of the ice / water

  10. Response of halocarbons to ocean acidification in the Arctic

    NARCIS (Netherlands)

    Hopkins, F.E.; Kimmance, S.A.; Stephens, J.A.; Bellerby, R.G.J.; Brussaard, C.P.D.; Czerny, J.; Schulz, K.G.; Archer, S.D.

    2013-01-01

    The potential effect of ocean acidification (OA) on seawater halocarbons in the Arctic was investigated during a mesocosm experiment in Spitsbergen in June-July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine similar to 50 m(3) mesocosms were studied under a range of pCO(2)

  11. High paleotemperatures in the Late Cretaceous Arctic ocean

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Jenkyns, H.; Forster, A.; Schouten, S.

    2004-01-01

    To understand the climate dynamics of the warm, equable greenhouse world of the Late Cretaceous period, it is important to determine polar palaeotemperatures. The early palaeoceanographic history of the Arctic Ocean has, however, remained largely unknown, because the sea floor and underlying deposit

  12. Response of halocarbons to ocean acidification in the Arctic

    NARCIS (Netherlands)

    F.E. Hopkins; S.A. Kimmance; J.A. Stephens; R.G.J. Bellerby; C.P.D. Brussaard; J. Czerny; K.G. Schulz; S.D. Archer

    2013-01-01

    The potential effect of ocean acidification (OA) on seawater halocarbons in the Arctic was investigated during a mesocosm experiment in Spitsbergen in June-July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine ~ 50 m3 mesocosms were studied under a range of pCO2 treatments f

  13. Fluvial and hydrothermal input of manganese into the Arctic Ocean

    NARCIS (Netherlands)

    Middag, R.; de Baar, H. J. W.; Laan, P.; Klunder, M. B.; Shaw, Timothy J.

    2011-01-01

    A total of 773 samples were analysed for dissolved manganese (Mn) in the Arctic Ocean aboard R. V. Polarstern during expedition ARK XXII/2 from 28 July until 07 October 2007 from Tromso (Norway) to Bremerhaven. Concentrations of Mn were elevated in the surface layer with concentrations of up to 6 nM

  14. The contiguous domains of Arctic Ocean advection: Trails of life and death

    Science.gov (United States)

    Wassmann, P.; Kosobokova, K. N.; Slagstad, D.; Drinkwater, K. F.; Hopcroft, R. R.; Moore, S. E.; Ellingsen, I.; Nelson, R. J.; Carmack, E.; Popova, E.; Berge, J.

    2015-12-01

    The central Arctic Ocean is not isolated, but tightly connected to the northern Pacific and Atlantic Oceans. Advection of nutrient-, detritus- and plankton-rich waters into the Arctic Ocean forms lengthy contiguous domains that connect subarctic with the arctic biota, supporting both primary production and higher trophic level consumers. In turn, the Arctic influences the physical, chemical and biological oceanography of adjacent subarctic waters through southward fluxes. However, exports of biomass out of the Arctic Ocean into both the Pacific and Atlantic Oceans are thought to be far smaller than the northward influx. Thus, Arctic Ocean ecosystems are net biomass beneficiaries through advection. The biotic impact of Atlantic- and Pacific-origin taxa in arctic waters depends on the total supply of allochthonously-produced biomass, their ability to survive as adults and their (unsuccessful) reproduction in the new environment. Thus, advective transport can be thought of as trails of life and death in the Arctic Ocean. Through direct and indirect (mammal stomachs, models) observations this overview presents information about the advection and fate of zooplankton in the Arctic Ocean, now and in the future. The main zooplankton organisms subjected to advection into and inside the Arctic Ocean are (a) oceanic expatriates of boreal Atlantic and Pacific origin, (b) oceanic Arctic residents and (c) neritic Arctic expatriates. As compared to the Pacific gateway the advective supply of zooplankton biomass through the Atlantic gateways is 2-3 times higher. Advection characterises how the main planktonic organisms interact along the contiguous domains and shows how the subarctic production regimes fuel life in the Arctic Ocean. The main differences in the advective regimes through the Pacific and Atlantic gateways are presented. The Arctic Ocean is, at least in some regions, a net heterotrophic ocean that - during the foreseeable global warming trend - will more and more rely

  15. Bromine measurements in ozone depleted air over the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. A. Neuman

    2010-07-01

    Full Text Available In situ measurements of ozone, photochemically active bromine compounds, and other trace gases over the Arctic Ocean in April 2008 are used to examine the chemistry and geographical extent of ozone depletion in the arctic marine boundary layer (MBL. Data were obtained from the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC study and the NASA DC-8 aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS study. Fast (1 s and sensitive (detection limits at the low pptv level measurements of BrCl and BrO were obtained from three different chemical ionization mass spectrometer (CIMS instruments, and soluble bromide was measured with a mist chamber. The CIMS instruments also detected Br2. Subsequent laboratory studies showed that HOBr rapidly converts to Br2 on the Teflon instrument inlets. This detected Br2 is identified as active bromine and represents a lower limit of the sum HOBr + Br2. The measured active bromine is shown to likely be HOBr during daytime flights in the arctic. In the MBL over the Arctic Ocean, soluble bromide and active bromine were consistently elevated and ozone was depleted. Ozone depletion and active bromine enhancement were confined to the MBL that was capped by a temperature inversion at 200–500 m altitude. In ozone-depleted air, BrO rarely exceeded 10 pptv and was always substantially lower than soluble bromide that was as high as 40 pptv. BrCl was rarely enhanced above the 2 pptv detection limit, either in the MBL, over Alaska, or in the arctic free troposphere.

  16. Ventilation of the Miocene Arctic Ocean: An idealized model study

    Science.gov (United States)

    Thompson, Bijoy; Nilsson, Johan; Nycander, Jonas; Jakobsson, Martin; Döös, Kristofer

    2010-11-01

    A model study of an idealized early Miocene Arctic Ocean has been undertaken. The work is motivated by the first drill core retrieved from the Lomonosov Ridge in the central Arctic Ocean, which suggests a transition from anoxic to oxic condition during the early Miocene, a feature presumably related to the opening of the Fram Strait. Here, the ventilation in a semienclosed basin, connected with the ocean through a strait with a sill, is examined using an ocean circulation model that includes a passive age tracer. In particular, we investigate how the ventilation depends on strait geometry, freshwater influx, and surface wind stress. We find that the turnover time, characterizing the bulk ventilation rate, is primarily controlled by the strait width and the wind stress. Generally, the oldest water in the basin is encountered near the sill depth, but wind forcing displaces the oldest water downward. For narrow straits, the turnover time gives an upper bound on the mean age of the basin water. The results have implications when translating local oxygen conditions, recorded in the sediment sequence from the Lomonosov Ridge, to basin-scale circulation patterns. Further, the results indicate that the early Miocene Arctic Ocean became well ventilated when the Fram Strait reached a width of about 100 km.

  17. Geological Structure and History of the Arctic Ocean

    Science.gov (United States)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey; Sobolev, Nikolay; Kashubin, Sergey; Pospelov, Igor; Tolmacheva, Tatiana; Petrov, Eugeny

    2016-04-01

    New data on geological structure of the deep-water part of the Arctic Basin have been integrated in the joint project of Arctic states - the Atlas of maps of the Circumpolar Arctic. Geological (CGS, 2009) and potential field (NGS, 2009) maps were published as part of the Atlas; tectonic (Russia) and mineral resources (Norway) maps are being completed. The Arctic basement map is one of supplements to the tectonic map. It shows the Eurasian basin with oceanic crust and submerged margins of adjacent continents: the Barents-Kara, Amerasian ("Amerasian basin") and the Canada-Greenland. These margins are characterized by strained and thinned crust with the upper crust layer, almost extinct in places (South Barents and Makarov basins). In the Central Arctic elevations, seismic studies and investigation of seabed rock samples resulted in the identification of a craton with the Early Precambrian crust (near-polar part of the Lomonosov Ridge - Alpha-Mendeleev Rise). Its basement presumably consists of gneiss granite (2.6-2.2 Ga), and the cover is composed of Proterozoic quartzite sandstone and dolomite overlain with unconformity and break in sedimentation by Devonian-Triassic limestone with fauna and terrigenous rocks. The old crust is surrounded by accretion belts of Timanides and Grenvillides. Folded belts with the Late Precambrian crust are reworked by Caledonian-Ellesmerian and the Late Mesozoic movements. Structures of the South Anuy - Angayucham ophiolite suture reworked in the Early Cretaceous are separated from Mesozoides proper of the Pacific - Verkhoyansk-Kolyma and Koryak-Kamchatka belts. The complicated modern ensemble of structures of the basement and the continental frame of the Arctic Ocean was formed as a result of the conjugate evolution and interaction of the three major oceans of the Earth: Paleoasian, Paleoatlantic and Paleopacific.

  18. Distribution of radium-224 in the western Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    QIU Yusheng; CHEN Min; LI Yanping

    2005-01-01

    Radium-224 activities in the western Arctic Ocean were measured via ship-board 220Rn emanation technique during the Second Chinese National Arctic Expedition. The results showed that the 224Ra activities in the study areas ranged from being less than 0.08 to 3.58 Bq/m3, with an average of 0.23 Bq/m3. The low 224Ra concentration in the surface water was attributed to the influence of sea ice melted water. The horizontal distribution of surface 224Ra in the western Arctic Ocean showed a high 224Ra characteristics occurred along the slope around 160°W, providing evidence for the importance of ice-rafted sediments to controlling the distribution of radium isotopes in the Arctic Ocean. Mostly, 224Ra concentrations increased with the depth in the shelf region and reached a maximum at 75 m at the central Canada Basin, which further confirms the importance of the transport of shelf bottom water to maintaining the upper halocline layer in the Canada Basin.

  19. Low Frequency Attenuation in the Arctic Ocean

    Science.gov (United States)

    2016-06-07

    for the Arctic , however, this term is predominantly determined by scattering loss from the rough ice canopy, and that it is two orders of magnitude...absorption by two orders of magnitude. The most likely mechanism is scattering from the rough ice canopy. Theoretical estimates of the scattering loss ...models of the ice canopy having varying degrees of realism. All theoretical estimates for scattering loss , irrespective of the particular model for the

  20. Dissolved iron in the Arctic Ocean: Important role of hydrothermal sources, shelf input and scavenging removal

    NARCIS (Netherlands)

    Klunder, M.B.; Laan, P.; Middag, R.; de Baar, H.J.W.; Bakker, K.

    2012-01-01

    Arctic Ocean waters exchange with the North Atlantic, and thus dissolved iron (DFe) in the Arctic has implications for the global Fe cycle. We present deep water (>250 m) DFe concentrations of the Central Arctic Ocean (Nansen, Amundsen and Makarov Basins). The DFe concentration in the deep waters va

  1. Dissolved iron in the Arctic Ocean : Important role of hydrothermal sources, shelf input and scavenging removal

    NARCIS (Netherlands)

    Klunder, M. B.; Laan, P.; Middag, R.; de Baar, H. J. W.; Bakker, K.

    2012-01-01

    Arctic Ocean waters exchange with the North Atlantic, and thus dissolved iron (DFe) in the Arctic has implications for the global Fe cycle. We present deep water (>250 m) DFe concentrations of the Central Arctic Ocean (Nansen, Amundsen and Makarov Basins). The DFe concentration in the deep waters va

  2. Biological productivity and carbon cycling in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Primary production, bacterial production, particulate organic carbon fluxes and organic carbon burial rates were quantified during the summer period of 1999 in the Arctic Ocean via 14C uptake, 3H uptake, 234Th/238U disequilibrium and 210Pbex dating, respectively. The integrated primary production in the water column was as high as 197 mmolC/(m2@d) in the Chukchi shelf and was 3.8 mmolC/(m2@d) in the Canada Basin. These rates are higher than those reported previously. The ratios of bacterial production to primary production in the study region were higher than 0.5, indicating that microbial activity is not depressed but important in cold Arctic waters. 234Th/238U disequilibria were evident at the station in the Canada Basin. The presence of significant 234Th deficiency suggested that scavenging and removal processes are also important to biogeochemical cycles of trace elements in the Arctic Ocean. Particulate organic carbon export flux was estimated to be 1.0 mmolC/(m2@d). Measurements of sediment excess 210Pb profile in the Chukchi shelf allowed us to estimate the amount of organic carbon buried in the bottom sediment, which ranged from 25 to 35 mmolC/(m2@d) and represented about 59%-82% of the mean primary production in the euphotic zone. Overall, our results indicated that the Arctic Ocean has active carbon cycling and is not a biological desert as previously believed. Therefore, the Arctic Ocean may play an important role in the global carbon cycle and climate change.

  3. Early Student Support for the Study of Inertial Motions in the Arctic Ocean

    Science.gov (United States)

    2015-09-30

    impacts how temperature , salinity , and other properties (tracers, nutrients, etc.) evolve in the upper Arctic Ocean (Rainville et al. 2011...in the Arctic Ocean Luc Rainville Applied Physics Laboratory 1013 NE 40th Street Seattle, WA 98105 phone: (206) 685-4058, fax: (206) 543... Ocean sea-ice extent has been a topic of concern with far reaching effects. At least seasonally, there are good reasons to believe that the Arctic Ocean

  4. Evaluation of Arctic Sea Ice Thickness Simulated by Arctic Ocean Model Intercomparison Project Models

    Science.gov (United States)

    Johnson, Mark; Proshuntinsky, Andrew; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nikolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; De Cuevas, Beverly

    2012-01-01

    Six Arctic Ocean Model Intercomparison Project model simulations are compared with estimates of sea ice thickness derived from pan-Arctic satellite freeboard measurements (2004-2008); airborne electromagnetic measurements (2001-2009); ice draft data from moored instruments in Fram Strait, the Greenland Sea, and the Beaufort Sea (1992-2008) and from submarines (1975-2000); and drill hole data from the Arctic basin, Laptev, and East Siberian marginal seas (1982-1986) and coastal stations (1998-2009). Despite an assessment of six models that differ in numerical methods, resolution, domain, forcing, and boundary conditions, the models generally overestimate the thickness of measured ice thinner than approximately 2 mand underestimate the thickness of ice measured thicker than about approximately 2m. In the regions of flat immobile landfast ice (shallow Siberian Seas with depths less than 25-30 m), the models generally overestimate both the total observed sea ice thickness and rates of September and October ice growth from observations by more than 4 times and more than one standard deviation, respectively. The models do not reproduce conditions of fast ice formation and growth. Instead, the modeled fast ice is replaced with pack ice which drifts, generating ridges of increasing ice thickness, in addition to thermodynamic ice growth. Considering all observational data sets, the better correlations and smaller differences from observations are from the Estimating the Circulation and Climate of the Ocean, Phase II and Pan-Arctic Ice Ocean Modeling and Assimilation System models.

  5. Preliminary Geospatial Analysis of Arctic Ocean Hydrocarbon Resources

    Energy Technology Data Exchange (ETDEWEB)

    Long, Philip E.; Wurstner, Signe K.; Sullivan, E. C.; Schaef, Herbert T.; Bradley, Donald J.

    2008-10-01

    Ice coverage of the Arctic Ocean is predicted to become thinner and to cover less area with time. The combination of more ice-free waters for exploration and navigation, along with increasing demand for hydrocarbons and improvements in technologies for the discovery and exploitation of new hydrocarbon resources have focused attention on the hydrocarbon potential of the Arctic Basin and its margins. The purpose of this document is to 1) summarize results of a review of published hydrocarbon resources in the Arctic, including both conventional oil and gas and methane hydrates and 2) develop a set of digital maps of the hydrocarbon potential of the Arctic Ocean. These maps can be combined with predictions of ice-free areas to enable estimates of the likely regions and sequence of hydrocarbon production development in the Arctic. In this report, conventional oil and gas resources are explicitly linked with potential gas hydrate resources. This has not been attempted previously and is particularly powerful as the likelihood of gas production from marine gas hydrates increases. Available or planned infrastructure, such as pipelines, combined with the geospatial distribution of hydrocarbons is a very strong determinant of the temporal-spatial development of Arctic hydrocarbon resources. Significant unknowns decrease the certainty of predictions for development of hydrocarbon resources. These include: 1) Areas in the Russian Arctic that are poorly mapped, 2) Disputed ownership: primarily the Lomonosov Ridge, 3) Lack of detailed information on gas hydrate distribution, and 4) Technical risk associated with the ability to extract methane gas from gas hydrates. Logistics may control areas of exploration more than hydrocarbon potential. Accessibility, established ownership, and leasing of exploration blocks may trump quality of source rock, reservoir, and size of target. With this in mind, the main areas that are likely to be explored first are the Bering Strait and Chukchi

  6. Methane Emissions from the Arctic Ocean to the Atmosphere

    Science.gov (United States)

    Platt, Stephen; Hermansen, Ova; Schmidbauer, Norbert; Pisso, Ignacio; Silyakova, Anna; Ferré, Benedicte; Lowry, Dave; Percival, Carl; Mienert, Jürgen; Myhre, Cathrine Lund

    2015-04-01

    The release of methane (CH4) presently stored in vast hydrate deposits under the seafloor is a potential climate tipping point and a major uncertainty in the global methane budget. Significant methane hydrate deposits are located in shallow waters in the Arctic where they may destabilise, releasing methane to the atmosphere due to ocean warming. To address this issue the Methane Emissions from Arctic Ocean to Atmosphere (MOCA, http://moca.nilu.no/) project was established in cooperation with the CAGE Centre of Excellence (http:cage.uit.no/). State-of-the-art oceanographic and atmospheric measurement techniques were applied over a large area of the Arctic including northern Norway, the Barents Sea, and areas of shallow water around Svalbard during summer 2014. Oceanographic measurements included the deployment of 63 measurement stations (temperature, salinity, density, oxygen, fluorescence, turbidity, etc.), water column sampling (CH4, nitrate, phosphate, silicates), and echo sounding (revealing locations where streams of gas bubbles are vented). Atmospheric on-line measurements were performed aboard the research vessel Helmer Hanssen (CH4, CO2, CO, meteorological parameters) and during a flight campaign (CH4, etc.). Air samples were collected for isotopic analysis (13C, 2H) and quantification of other hydrocarbons (ethane, propane, etc.). Finally, atmospheric measurements are compared with long term data sets from the nearby Zeppelin Mountain monitoring station (Ny Ålesund, Svalbard). Back-trajectory analysis and FLEXPART modelling are used to rule out non-local sources. Here we present an overview of all of these activities and the first results from MOCA in cooperation with CAGE - Centre for Arctic Gas Hydrate, and Climate at UiT, The Arctic University of Norway. We demonstrate that there are hotspots of activity where hydrocarbons are being emitted from the ocean, while in some areas emissions are surprisingly well contained by local biological and hydrological

  7. Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

    Science.gov (United States)

    Marzen, Rachel; DeNinno, Lauren H.; Cronin, Thomas M.

    2016-01-01

    Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

  8. Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

    Science.gov (United States)

    Marzen, Rachel E.; DeNinno, Lauren H.; Cronin, Thomas M.

    2016-10-01

    Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

  9. Atmospheric Input of Particulate Matter In The Arctic Ocean

    Science.gov (United States)

    Shevchenko, V. P.; Klyuvitkin, A. A.; Kriews, M.; Lisitzin, A. P.; Nothig, E.-M.; Novigatsky, A. N.; Smirnov, V. V.; Stein, R.; Vinogradova, A. A.

    Numerous studies have shown that aerosols in the Arctic are of importance for atmo- spheric chemistry and climate. But up to now atmospheric input of particulate matter in the Arctic Ocean is studied insufficiently. We began aerosol research in the Arctic marine boundary layer in 1991. In this presentation we summarized data on parti- cle size and composition of aerosols and on particulate material in snow cover col- lected during 10 years (1991-2000) onboard of Russian research vessels and German icebreaker "Polarstern". Concentrations of most chemical elements are nearly of the same order as literature data from other Arctic areas. A catastrophic increase of ele- ment content due to anthropogenic factor in the summer-autumn has not been found. The balance calculations based on our and literature data show that the contribution of aerosols to formation of the sedimentary material in the Arctic is close to the con- tribution of the river sediments beyond the marginal filters of rivers. For some chem- ical elements (Pb, Sb, Se, V) the aeolian source is very important. Our studies were financially supported by the Russian Foundation of Basic Research (grants RFBR 96- 05-00043 and 98-05-64279), DFG (grant STE-412/10-2) and by German and Russian Ministries for Science and Technology in the frame of Otto Schmidt Laboratory fel- lowship and "Laptev Sea 2000" project.

  10. Assimilation impacts on Arctic Ocean circulation, heat and freshwater budgets

    Science.gov (United States)

    Zuo, Hao; Mugford, Ruth I.; Haines, Keith; Smith, Gregory C.

    We investigate the Arctic basin circulation, freshwater content (FWC) and heat budget by using a high-resolution global coupled ice-ocean model implemented with a state-of-the-art data assimilation scheme. We demonstrate that, despite a very sparse dataset, by assimilating hydrographic data in and near the Arctic basin, the initial warm bias and drift in the control run is successfully corrected, reproducing a much more realistic vertical and horizontal structure to the cyclonic boundary current carrying the Atlantic Water (AW) along the Siberian shelves in the reanalysis run. The Beaufort Gyre structure and FWC and variability are also more accurately reproduced. Small but important changes in the strait exchange flows are found which lead to more balanced budgets in the reanalysis run. Assimilation fluxes dominate the basin budgets over the first 10 years (P1: 1987-1996) of the reanalysis for both heat and FWC, after which the drifting Arctic upper water properties have been restored to realistic values. For the later period (P2: 1997-2004), the Arctic heat budget is almost balanced without assimilation contributions, while the freshwater budget shows reduced assimilation contributions compensating largely for surface salinity damping, which was extremely strong in this run. A downward trend in freshwater export at the Canadian Straits and Fram Strait is found in period P2, associated with Beaufort Gyre recharge. A detailed comparison with observations and previous model studies at the individual Arctic straits is also included.

  11. Climate Change and China as a Global Emerging Regulatory Sea Power in the Arctic Ocean

    DEFF Research Database (Denmark)

    Cassotta Pertoldi-Bianchi, Sandra; Hossain, Kamrul; Ren, Jingzheng;

    2015-01-01

    The impact of climate change in the Arctic Ocean such as ice melting and ice retreat facilitates natural resources extraction. Arctic fossil fuel becomes the drivers of geopolitical changes in the Arctic Ocean. Climate change facilitates natural resource extractions and increases competition...... between states and can result in tensions, even military ones. This article investigates through a political and legal analysis the role of China as an emerging regulatory sea power in the Arctic Ocean given its assertive “energy hungry country behaviour” in the Arctic Ocean. The United Nations Convention...... on the Law of the Sea (UNCLOS) and the Arctic Council (AC) are taken into consideration under climate change effects, to assess how global legal frameworks and institutions can deal with China’s strategy in the Arctic Ocean. China’s is moving away from its role as “humble power” to one of “informal...

  12. The Arctic Ocean ice balance - A Kalman smoother estimate

    Science.gov (United States)

    Thomas, D. R.; Rothrock, D. A.

    1993-01-01

    The methodology of Kalman filtering and smoothing is used to integrate a 7-year time series of buoy-derived ice motion fields and satellite passive microwave observations. The result is a record of the concentrations of open water, first-year ice, and multiyear ice that we believe is better than the estimates based on the microwave data alone. The Kalman procedure interprets the evolution of the ice cover in terms of advection, melt, growth, ridging, and aging of first-year into multiyear ice. Generally, the regions along the coasts of Alaska and Siberia and the area just north of Fram Strait are sources of first-year ice, with the rest of the Arctic Ocean acting as a sink for first-year ice via ridging and aging. All the Arctic Ocean except for the Beaufort and Chukchi seas is a source of multiyear ice, with the Chukchi being the only internal multiyear ice sink. Export through Fram Strait is a major ice sink, but we find only about two-thirds the export and greater interannual variation than found in previous studies. There is no discernible trend in the area of multiyear ice in the Arctic Ocean during the 7 years.

  13. Critical Metals In Western Arctic Ocean Ferromanganese Mineral Deposits

    Science.gov (United States)

    Hein, J. R.; Spinardi, F.; Conrad, T. A.; Conrad, J. E.; Genetti, J.

    2013-12-01

    Little exploration for minerals has occurred in the Arctic Ocean due to ice cover and the remote location. Small deposits of seafloor massive sulfides that are rich in copper and zinc occur on Gakkel Ridge, which extends from Greenland to the Laptev Sea, and on Kolbeinsey and Mohns ridges, both located between Greenland and mainland Europe. However, rocks were recently collected by dredge along the western margin of the Canada Basin as part of the U.S. Extended Continental Shelf (ECS) program north of Alaska. Sample sites include steep escarpments on the Chukchi Borderland, a newly discovered seamount informally named Healy seamount, the southern part of Alpha-Mendeleev Ridge, and several basement outcrops in Nautilus Basin. These dredge hauls yielded three types of metal-rich mineralized deposits: ferromanganese crusts, ferromanganese nodules, and hydrothermal iron and manganese deposits. Chemical analyses of 43 crust and nodule samples show high contents of many critical metals needed for high-technology, green-technology, and energy and military applications, including cobalt (to 0.3 wt.%), vanadium (to 0.12 wt.%), zirconium (to 459 grams/tonne=ppm), molybdenum (to 453 g/t), the rare-earth elements (including scandium and yttrium; yttrium to 229 g/t), lithium (to 205 g/t), tungsten (to 64 g/t), and gallium (to 26 g/t). The metal contents of these Arctic Ocean crusts and nodules are comparable to those found throughout the global ocean, however, these Arctic Ocean samples are the first that have been found to be enriched in rare metal scandium. The metal contents of these samples indicate a diagenetic component. Crusts typically form by precipitation of metal oxides solely from seawater (hydrogenetic) onto rock surfaces producing a pavement, whereas nodules form by accretion of metal oxides, from both seawater and pore waters (diagenetic), around a nucleus on the surface of soft sediment. The best evidence for this diagenetic input to the crusts is that crusts

  14. Arctic Ocean Freshwater: How Robust are Model Simulations

    Science.gov (United States)

    Jahn, A.; Aksenov, Y.; deCuevas, B. A.; deSteur, L.; Haekkinen, S.; Hansen, E.; Herbaut, C.; Houssais, M.-N.; Karcher, M.; Kauker, F.; Lique, C.; Nguyen, A.; Pemberton, P.; Worthen, D.; Zhang, J.

    2012-01-01

    The Arctic freshwater (FW) has been the focus of many modeling studies, due to the potential impact of Arctic FW on the deep water formation in the North Atlantic. A comparison of the hindcasts from ten ocean-sea ice models shows that the simulation of the Arctic FW budget is quite different in the investigated models. While they agree on the general sink and source terms of the Arctic FW budget, the long-term means as well as the variability of the FW export vary among models. The best model-to-model agreement is found for the interannual and seasonal variability of the solid FW export and the solid FW storage, which also agree well with observations. For the interannual and seasonal variability of the liquid FW export, the agreement among models is better for the Canadian Arctic Archipelago (CAA) than for Fram Strait. The reason for this is that models are more consistent in simulating volume flux anomalies than salinity anomalies and volume-flux anomalies dominate the liquid FW export variability in the CAA but not in Fram Strait. The seasonal cycle of the liquid FW export generally shows a better agreement among models than the interannual variability, and compared to observations the models capture the seasonality of the liquid FW export rather well. In order to improve future simulations of the Arctic FW budget, the simulation of the salinity field needs to be improved, so that model results on the variability of the liquid FW export and storage become more robust.

  15. Acoustic Mode Coherence in the Arctic Ocean

    Science.gov (United States)

    1986-05-01

    oteshetoe h cors o te xprien, ndwa aanoedat$20 , .1 EonIIMa. 94a Thecou igur 3-t : ofitrt oaf t raMitt d o TRISTlEN leo Cam., rn w 1082arate perios of2...Technical Report LDGO-82-3, LDGO, Columbia University, Palisades, NY, 1982. [79] I. Tolstoy and C.S. Clay. Ocean Acoustics. McGraw-Hill Book Company

  16. Aragonite undersaturation in the Arctic Ocean: effects of ocean acidification and sea ice melt.

    Science.gov (United States)

    Yamamoto-Kawai, Michiyo; McLaughlin, Fiona A; Carmack, Eddy C; Nishino, Shigeto; Shimada, Koji

    2009-11-20

    The increase in anthropogenic carbon dioxide emissions and attendant increase in ocean acidification and sea ice melt act together to decrease the saturation state of calcium carbonate in the Canada Basin of the Arctic Ocean. In 2008, surface waters were undersaturated with respect to aragonite, a relatively soluble form of calcium carbonate found in plankton and invertebrates. Undersaturation was found to be a direct consequence of the recent extensive melting of sea ice in the Canada Basin. In addition, the retreat of the ice edge well past the shelf-break has produced conditions favorable to enhanced upwelling of subsurface, aragonite-undersaturated water onto the Arctic continental shelf. Undersaturation will affect both planktonic and benthic calcifying biota and therefore the composition of the Arctic ecosystem.

  17. Comparison of air-sea fluxes of CO2 in the Southern Ocean and the western Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    CHEN Liqi; GAO Zhongyong; YANG Xulin; WANG Weiqiang

    2004-01-01

    The data were collected during Chinese Arctic and Antarctic Expeditions in the western Arctic Ocean and the marginal sea ice zone (MSIZ) of the Southern Ocean, respectively in the boreal summer from July to September of 1999 and in the austral summer from December of 1999 to January of 2000. The concentrations of CO2 in surface water of the survey regions would mostly present lower than those in the atmosphere. A significant biological driving force could also been observed in summer waters in both of the above oceans. Air to sea CO2 fluxes were also calculated to compare oceanic uptake capacity of CO2 in both oceans with the world oceans using Liss, Wanninkhof,and Jacobs' s methods. The averaged CO2 fluxes of air to sea in the western Arctic Ocean or in the MSIZ of the Southern Ocean doubled that in the world oceans.

  18. Processes of multibathyal aragonite undersaturation in the Arctic Ocean

    Science.gov (United States)

    Wynn, J.G.; Robbins, L.L.; Anderson, L.G.

    2016-01-01

    During 3 years of study (2010–2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic-derived and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite undersaturation zone, from the surface to ∼30 m depth is characterized by relatively low alkalinity and other dissolved ions. Besides local influence of biological processes on aragonite undersaturation of shallow coastal waters, the nature of this zone is consistent with dilution by sea-ice melt and invasion of anthropogenic CO2 from the atmosphere. A second undersaturated zone at ∼90–220 m depth (salinity ∼31.8–35.4) occurs within the Arctic Halocline and is characterized by elevated pCO2 and nutrients. The nature of this horizon is consistent with remineralization of organic matter on shallow continental shelves bordering the Canada Basin and the input of the nutrients and CO2 entrained by currents from the Pacific Inlet. Finally, the deepest aragonite undersaturation zone is at greater than 2000 m depth and is controlled by similar processes as deep aragonite saturation horizons in the Atlantic and Pacific Oceans. The comparatively shallow depth of this deepest aragonite saturation horizon in the Arctic is maintained by relatively low temperatures, and stable chemical composition. Understanding the mechanisms controlling the distribution of these aragonite undersaturation zones, and the time scales over which they operate will be crucial to refine predictive models.

  19. Proxy Constraints on a Warm, Fresh Late Cretaceous Arctic Ocean

    Science.gov (United States)

    Super, J. R.; Li, H.; Pagani, M.; Chin, K.

    2015-12-01

    The warm Late Cretaceous is thought to have been characterized by open Arctic Ocean temperatures upwards of 15°C (Jenkyns et al., 2004). The high temperatures and low equator-to-pole temperature gradient have proven difficult to reproduce in paleoclimate models, with the role of the atmospheric hydrologic cycle in heat transport being particularly uncertain. Here, sediments, coprolites and fish teeth of Santonian-Campanian age from two high-latitude mixed terrestrial and marine sections on Devon Island in the Canadian High Arctic (Chin et al., 2008) were analyzed using a suite of organic and inorganic proxies to evaluate the temperature and salinity of Arctic seawater. Surface temperature estimates were derived from TEX86 estimates of near-shore, shallow (~100 meters depth) marine sediments (Witkowski et al., 2011) and MBT-CBT estimates from terrestrial intervals and both suggest mean annual temperatures of ~20°C, consistent with previous estimates considering the more southerly location of Devon Island. The oxygen isotope composition of non-diagenetic phosphate from vertebrate coprolites and bony fish teeth were then measured, giving values ranging from +13‰ to +19‰. Assuming the TEX86 temperatures are valid and using the temperature calibration of Puceat 2010, the δ18O values of coprolites imply Arctic Ocean seawater δ18O values between -4‰ and -10‰, implying very fresh conditions. Lastly, the δD of precipitation will be estimated from the hydrogen isotope composition of higher plant leaf waxes (C-25, C-27, C-29 and C-31 n-alkanes) from both terrestrial and marine intervals. Data are used to model the salinity of seawater and the meteoric relationship between δD and δ18O, thereby helping to evaluate the northern high-latitude meteoric water line of the Late Cretaceous.

  20. Latitudinal variation of phytoplankton communities in the western Arctic Ocean

    Science.gov (United States)

    Min Joo, Hyoung; Lee, Sang H.; Won Jung, Seung; Dahms, Hans-Uwe; Hwan Lee, Jin

    2012-12-01

    Recent studies have shown that photosynthetic eukaryotes are an active and often dominant component of Arctic phytoplankton assemblages. In order to explore this notion at a large scale, samples were collected to investigate the community structure and biovolume of phytoplankton along a transect in the western Arctic Ocean. The transect included 37 stations at the surface and subsurface chlorophyll a maximum (SCM) depths in the Bering Sea, Chukchi Sea, and Canadian Basin from July 19 to September 5, 2008. Phytoplankton (>2 μm) were identified and counted. A cluster analysis of abundance and biovolume data revealed different assemblages over the shelf, slope, and basin regions. Phytoplankton communities were composed of 71 taxa representing Dinophyceae, Cryptophyceae, Bacillariophyceae, Chrysophyceae, Dictyochophyceae, Prasinophyceae, and Prymnesiophyceae. The most abundant species were of pico- to nano-size at the surface and SCM depths at most stations. Nano- and pico-sized phytoplankton appeared to be dominant in the Bering Sea, whereas diatoms and nano-sized plankton provided the majority of taxon diversity in the Bering Strait and in the Chukchi Sea. From the western Bering Sea to the Bering Strait, the abundance, biovolume, and species diversity of phytoplankton provided a marked latitudinal gradient towards the central Arctic. Although pico- and nano-sized phytoplankton contributed most to cell abundance, their chlorophyll a contents and biovolumes were less than those of the larger micro-sized taxa. Micro-sized phytoplankton contributed most to the biovolume in the largely ice-free waters of the western Arctic Ocean during summer 2008.

  1. Processes of multibathyal aragonite undersaturation in the Arctic Ocean

    Science.gov (United States)

    Wynn, J. G.; Robbins, L. L.; Anderson, L. G.

    2016-11-01

    During 3 years of study (2010-2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic-derived and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite undersaturation zone, from the surface to ˜30 m depth is characterized by relatively low alkalinity and other dissolved ions. Besides local influence of biological processes on aragonite undersaturation of shallow coastal waters, the nature of this zone is consistent with dilution by sea-ice melt and invasion of anthropogenic CO2 from the atmosphere. A second undersaturated zone at ˜90-220 m depth (salinity ˜31.8-35.4) occurs within the Arctic Halocline and is characterized by elevated pCO2 and nutrients. The nature of this horizon is consistent with remineralization of organic matter on shallow continental shelves bordering the Canada Basin and the input of the nutrients and CO2 entrained by currents from the Pacific Inlet. Finally, the deepest aragonite undersaturation zone is at greater than 2000 m depth and is controlled by similar processes as deep aragonite saturation horizons in the Atlantic and Pacific Oceans. The comparatively shallow depth of this deepest aragonite saturation horizon in the Arctic is maintained by relatively low temperatures, and stable chemical composition. Understanding the mechanisms controlling the distribution of these aragonite undersaturation zones, and the time scales over which they operate will be crucial to refine predictive models.

  2. The early Miocene onset of a ventilated circulation regime in the Arctic Ocean.

    Science.gov (United States)

    Jakobsson, Martin; Backman, Jan; Rudels, Bert; Nycander, Jonas; Frank, Martin; Mayer, Larry; Jokat, Wilfried; Sangiorgi, Francesca; O'Regan, Matthew; Brinkhuis, Henk; King, John; Moran, Kathryn

    2007-06-21

    Deep-water formation in the northern North Atlantic Ocean and the Arctic Ocean is a key driver of the global thermohaline circulation and hence also of global climate. Deciphering the history of the circulation regime in the Arctic Ocean has long been prevented by the lack of data from cores of Cenozoic sediments from the Arctic's deep-sea floor. Similarly, the timing of the opening of a connection between the northern North Atlantic and the Arctic Ocean, permitting deep-water exchange, has been poorly constrained. This situation changed when the first drill cores were recovered from the central Arctic Ocean. Here we use these cores to show that the transition from poorly oxygenated to fully oxygenated ('ventilated') conditions in the Arctic Ocean occurred during the later part of early Miocene times. We attribute this pronounced change in ventilation regime to the opening of the Fram Strait. A palaeo-geographic and palaeo-bathymetric reconstruction of the Arctic Ocean, together with a physical oceanographic analysis of the evolving strait and sill conditions in the Fram Strait, suggests that the Arctic Ocean went from an oxygen-poor 'lake stage', to a transitional 'estuarine sea' phase with variable ventilation, and finally to the fully ventilated 'ocean' phase 17.5 Myr ago. The timing of this palaeo-oceanographic change coincides with the onset of the middle Miocene climatic optimum, although it remains unclear if there is a causal relationship between these two events.

  3. Arctic Ocean Drift Tracks from Ships, Buoys and Manned Research Stations, 1872-1973

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Thirty-four drift tracks in the Arctic Ocean pack ice are collected in a unified tabular data format, one file per track. Data are from drifting ships, manned...

  4. Western Arctic Ocean temperature variability during the last 8000 years

    Science.gov (United States)

    Farmer, Jesse R.; Cronin, Thomas M.; De Vernal, Anne; Dwyer, Gary S.; Keigwin, Loyd D.; Thunell, Robert C.

    2011-01-01

    We reconstructed subsurface (∼200–400 m) ocean temperature and sea-ice cover in the Canada Basin, western Arctic Ocean from foraminiferal δ18O, ostracode Mg/Ca ratios, and dinocyst assemblages from two sediment core records covering the last 8000 years. Results show mean temperature varied from −1 to 0.5°C and −0.5 to 1.5°C at 203 and 369 m water depths, respectively. Centennial-scale warm periods in subsurface temperature records correspond to reductions in summer sea-ice cover inferred from dinocyst assemblages around 6.5 ka, 3.5 ka, 1.8 ka and during the 15th century Common Era. These changes may reflect centennial changes in the temperature and/or strength of inflowing Atlantic Layer water originating in the eastern Arctic Ocean. By comparison, the 0.5 to 0.7°C warm temperature anomaly identified in oceanographic records from the Atlantic Layer of the Canada Basin exceeded reconstructed Atlantic Layer temperatures for the last 1200 years by about 0.5°C.

  5. First evaluation of MyOcean altimetric data in the Arctic Ocean

    DEFF Research Database (Denmark)

    Cheng, Yongcun; Andersen, Ole Baltazar; Knudsen, Per

    2012-01-01

    The MyOcean V2 preliminary (V2p) data set of weekly gridded sea level anomaly (SLA) maps from 1993 to 2009 over the Arctic region is evaluated against existing altimetric data sets and tide gauge data. Compared with DUACS V3.0.0 (Data Unification and Altimeter Combination System) data set, MyOcean...... V2p data set improves spatial coverage and quality as well as maximum temporal correlation coefficient between altimetry and tide gauge data. The estimated amplitude of sea level annual signal and linear sea level trend from MyOcean data set are evaluated against altimetry from DUACS and RADS (Radar...... Altimeter Database System), the SODA (Simple Ocean Data Assimilation) ocean reanalysis and tide gauge data sets from PSMSL (Permanent Service for Mean Sea Level). The results show that the MyOcean data set fits in-situ measurements better than DUACS data set with respect to amplitude of annual signal...

  6. The emergence of modern sea ice cover in the Arctic Ocean.

    Science.gov (United States)

    Knies, Jochen; Cabedo-Sanz, Patricia; Belt, Simon T; Baranwal, Soma; Fietz, Susanne; Rosell-Melé, Antoni

    2014-11-28

    Arctic sea ice coverage is shrinking in response to global climate change and summer ice-free conditions in the Arctic Ocean are predicted by the end of the century. The validity of this prediction could potentially be tested through the reconstruction of the climate of the Pliocene epoch (5.33-2.58 million years ago), an analogue of a future warmer Earth. Here we show that, in the Eurasian sector of the Arctic Ocean, ice-free conditions prevailed in the early Pliocene until sea ice expanded from the central Arctic Ocean for the first time ca. 4 million years ago. Amplified by a rise in topography in several regions of the Arctic and enhanced freshening of the Arctic Ocean, sea ice expanded progressively in response to positive ice-albedo feedback mechanisms. Sea ice reached its modern winter maximum extension for the first time during the culmination of the Northern Hemisphere glaciation, ca. 2.6 million years ago.

  7. Mercury distribution and transport across the ocean-sea-ice-atmosphere interface in the Arctic Ocean.

    Science.gov (United States)

    Chaulk, Amanda; Stern, Gary A; Armstrong, Debbie; Barber, David G; Wang, Feiyue

    2011-03-01

    The Arctic sea-ice environment has been undergoing dramatic changes in the past decades; to which extent this will affect the deposition, fate, and effects of chemical contaminants remains virtually unknown. Here, we report the first study on the distribution and transport of mercury (Hg) across the ocean-sea-ice-atmosphere interface in the Southern Beaufort Sea of the Arctic Ocean. Despite being sampled at different sites under various atmospheric and snow cover conditions, Hg concentrations in first-year ice cores were generally low and varied within a remarkably narrow range (0.5-4 ng L(-1)), with the highest concentration always in the surface granular ice layer which is characterized by enriched particle and brine pocket concentration. Atmospheric Hg depletion events appeared not to be an important factor in determining Hg concentrations in sea ice except for frost flowers and in the melt season when snowpack Hg leaches into the sea ice. The multiyear ice core showed a unique cyclic feature in the Hg profile with multiple peaks potentially corresponding to each ice growing/melting season. The highest Hg concentrations (up to 70 ng L(-1)) were found in sea-ice brine and decrease as the melt season progresses. As brine is the primary habitat for microbial communities responsible for sustaining the food web in the Arctic Ocean, the high and seasonally changing Hg concentrations in brine and its potential transformation may have a major impact on Hg uptake in Arctic marine ecosystems under a changing climate.

  8. The 1994 Arctic Ocean Section. The First Major Scientific Crossing of the Arctic Ocean,

    Science.gov (United States)

    1996-09-01

    chlorofluorocarbons (CFCs), helium, oxygen, CO2 system components, AMS 14C, tritium, 18O, nutrients, salinity, trace metals, radionuclides and organic contaminants...spatial and temporal extremes in the rate of biological sequestration of atmospheric CO2 , ranging from oligotrophic conditions in the central Arctic to...paleoceanographic or paleoatmospheric circulation patterns and contribute to better paleoclimate reconstructions. Surface sediments collected along

  9. Estimating Summer Ocean Heating in the Arctic Ice Pack Using High-Resolution Satellite Imagery

    Science.gov (United States)

    2014-09-01

    requirement (Lee et al. 2012). As Suh (2011) discussed, Arctic sea ice is affected from both surface melting due to atmospheric conditions, as well as...OCEAN HEATING IN THE ARCTIC ICE PACK USING HIGH-RESOLUTION SATELLITE IMAGERY by Ander S. Heiles September 2014 Thesis Advisor: Timothy...September 2014 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE ESTIMATING SUMMER OCEAN HEATING IN THE ARCTIC ICE PACK

  10. Upper-Ocean Variability in the Arctic’s Amundsen and Nansen Basins

    Science.gov (United States)

    2015-09-30

    GOALS The PI group seeks to observe the upper Arctic Ocean using autonomous instrumentation and build understanding of the physical processes...OBJECTIVES Collect and analyze exploratory observations of upper- Arctic - Ocean velocity and thermohaline stratification variations in the Eurasian...sample like the systems deployed for the MIZ program. Specifically, vertical temperature , salinity and velocity profiles are being collected every 3

  11. The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean acidification impacts and potential feedbacks

    Directory of Open Access Journals (Sweden)

    J. T. Mathis

    2009-07-01

    Full Text Available At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO2 on the order of −65 to −175 Tg C year−1, contributing 5–14% to the global balance of CO2 sinks and sources. Because of this, the Arctic Ocean is an important influence on the global carbon cycle, with the marine carbon cycle and atmosphere-ocean CO2 exchanges sensitive to Arctic Ocean and global climate change feedbacks. In the near-term, further sea-ice loss and increases in phytoplankton growth rates are expected to increase the uptake of CO2 by Arctic surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO2 is expected to alter in response to environmental changes driven largely by climate. These changes are likely to continue to modify the physics, biogeochemistry, and ecology of the Arctic Ocean in ways that are not yet fully understood. In surface waters, sea-ice melt, river runoff, cooling and uptake of CO2 through air-sea gas exchange combine to decrease the calcium carbonate (CaCO3 mineral saturation states (Ω of seawater that is counteracted by seasonal phytoplankton primary production (PP. Biological processes drive divergent trajectories for Ω in surface and subsurface waters of Arctic shelves with subsurface water experiencing undersaturation with respect to aragonite and calcite. Thus, in response to increased sea-ice loss, warming and enhanced phytoplankton PP, the benthic ecosystem of the Arctic shelves are expected to be negatively impacted by the biological amplification of ocean acidification. This in turn reduces the ability of many species to produce CaCO3 shells or tests with profound implications for Arctic marine ecosystems.

  12. Remote sensing of ocean color in the Arctic

    Science.gov (United States)

    Maynard, N. G.

    1988-01-01

    The main objectives of the research are: to increase the understanding of biological production (and carbon fluxes) along the ice edge, in frontal regions, and in open water areas of the Arctic and the physical factors controlling that production through the use of satellite and aircraft remote sensing techniques; and to develop relationships between measured radiances from the Multichannel Aircraft Radiometer System (MARS) and the bio-optical properties of the water in the Arctic and adjacent seas. Several recent Coastal Zone Color Scanner (CZCS) studies in the Arctic have shown that, despite constraints imposed by cloud cover, satellite ocean color is a useful means of studying mesoscale physical and biological oceanographic phenomena at high latitudes. The imagery has provided detailed information on ice edge and frontal processes such as spring breakup and retreat of the ice edge, influence of ice on ice effects of stratification on phytoplankton production, river sediment transport, effects of spring runoff, water mass boundaries, circulation patterns, and eddy formation in Icelandic waters and in the Greenland, Barents, Norwegian, and Bering Seas.

  13. Distribution of crustal types in Canada Basin, Arctic Ocean

    Science.gov (United States)

    Chian, D.; Jackson, H. R.; Hutchinson, D. R.; Shimeld, J. W.; Oakey, G. N.; Lebedeva-Ivanova, N.; Li, Q.; Saltus, R. W.; Mosher, D. C.

    2016-11-01

    Seismic velocities determined from 70 sonobuoys widely distributed in Canada Basin were used to discriminate crustal types. Velocities of oceanic layer 3 (6.7-7.1 km/s), transitional (7.2-7.6 km/s) and continental crust (5.5-6.6 km/s) were used to distinguish crustal types. Potential field data supports the distribution of oceanic crust as a polygon with maximum dimensions of 340 km (east-west) by 590 km (north-south) and identification of the ocean-continent boundary (OCB). Paired magnetic anomalies are associated only with crust that has oceanic velocities. Furthermore, the interpreted top of oceanic crust on seismic reflection profiles is more irregular and sometimes shallower than adjacent transitional crust. The northern segment of the narrow Canada Basin Gravity Low (CBGL), often interpreted as a spreading center, bisects this zone of oceanic crust and coincides with the location of a prominent valley in seismic reflection profiles. Data coverage near the southern segment of CBGL is sparse. Velocities typical of transitional crust are determined east of it. Extension in this region, close to the inferred pole of rotation, may have been amagmatic. Offshore Alaska is a wide zone of thinned continental crust up to 300 km across. Published longer offset refraction experiments in the Basin confirm the depth to Moho and the lack of oceanic layer 3 velocities. Further north, toward Alpha Ridge and along Northwind Ridge, transitional crust is interpreted to be underplated or intruded by magmatism related to the emplacement of the High Arctic Large Igneous Province (HALIP). Although a rotational plate tectonic model is consistent with the extent of the conjugate magnetic anomalies that occupy only a portion of Canada Basin, it does not explain the asymmetrical configuration of the oceanic crust in the deep water portion of Canada Basin, and the unequal distribution of transitional and continental crust around the basin.

  14. SMOS sea surface salinity maps of the Arctic Ocean

    Science.gov (United States)

    Gabarro, Carolina; Olmedo, Estrella; Turiel, Antonio; Ballabrera-Poy, Joaquim; Martinez, Justino; Portabella, Marcos

    2016-04-01

    years of SMOS data acquisitions. The second is the modification of the filtering criterion to account for the statistical distributions of SSS at each ocean grid point. This allows retrieving a value of SSS which is less affected by outliers originated from RFI and other effects. We will provide an assessment of the quality of these new SSS products in the Arctic, as well as illustrate the potential of these maps to monitor the main river discharges to the Arctic Ocean. [1] Font, J.; Camps, A.; Borges, A.; Martín-Neira, M.; Boutin, J.; Reul, N.; Kerr, Y.; Hahne, A. & Mecklenburg, S. SMOS: The Challenging Sea Surface Salinity Measurement From Space Proceedings of the IEEE, 2010, 98, 649 -665

  15. Arctic Ocean sea ice drift origin derived from artificial radionuclides.

    Science.gov (United States)

    Cámara-Mor, P; Masqué, P; Garcia-Orellana, J; Cochran, J K; Mas, J L; Chamizo, E; Hanfland, C

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of (137)Cs and (239,240)Pu activities and the (240)Pu/(239)Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The (240)Pu/(239)Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the (240)Pu/(239)Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the (137)Cs and (239,240)Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  16. Residence time of the freshwater component in the Arctic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Ostlund, H.G.

    1982-03-20

    The time function of bomb tritium concentrations in river runoff to the Arctic Ocean has been reconstructed from published data on tritium in precipatatio 1959--1975. Tritium measurements on oceanic samples through the haloclinie exhibit strong linear relatioships between tritium concetrations (TU values) and salinity. These wates thus look like binary mixtures of Atlantic source water and freshwater runoff. Combining these data, the vintage of the freshwater component in the Arctic Basin has been determined assuming no other major tritium source. The relation indicates the average age of the freshwater component to be 11 +- 1 years in the Namsen Basin and the outflow and somewhat higher in the Canada Basin. According to ttitium/salinity data, a surface layer of 10--60 m is affected by sea ice melting and freezing in the Nansen Basin, and the thickness of this layer increases to 150--170 m toward the Canada Basin. There is tritium also in the deep waters, the unumixed Atlantic water, which points at residence times for that water not to exceed 17 years.

  17. Numerical simulations of the current state of waters and sea ice in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    E. N. Golubeva

    2015-01-01

    Full Text Available The paper presents results of numerical simulation of variability of the sea ice area and water circulation in the Arctic Ocean performed with use of the atmosphere reanalysis data for the period from middle of the last century to the present time. The model results reflect the ocean responses to changes of the atmosphere circulation regimes that manifests in changes of trajectories of waters coming into the Arctic Ocean from the Pacific and Atlantic oceans. The model results show influence of the Pacific and Atlantic waters on distribution and thickness of the Arctic ice. 

  18. The Biological Pump in the Cryopelagic Arctic Ocean (Invited)

    Science.gov (United States)

    Honjo, S.; Eglinton, T. I.

    2010-12-01

    Time-Series Sediment Trap data from the Arctic Ocean provides insight into oceanic uptake of CO2 in the cryopelagic ocean. One trap was tethered to an Ice Ocean Environmental Buoy at 200 m and drifted 1810 km within the Canada Basin from 79N, 132E to 77N, 131E in 1996-7. Another TS-trap, moored at 120 m, covered 2724 km from 75N, 142E to 80N 156E in 1997-8, traversed the cryopelagic basin and the hemipelagic Chukchi Rise. The 3rd TS-trap was moored at 3067 m in 2004-5 in the Canada Abyssal Plain in 3824 m beneath the cryopelagic drift route of the 120 m trap. These three TS-traps intercepted settling particles in 21 increments over 17 days for a total of 357 days each. The annual export flux of FCorg (POC) was 7 mmolC m-2yr-1, and the ballast particle fluxes, FCinorg (CaCO3) and FSibio (bio-opal), were 2 mmolC and 0.3 mmolSi m-2yr-1 in the 200m trap. Notably these export fluxes were a few orders of magnitude smaller than global epipelagic fluxes where the biological pump represents an essential vehicle for carbon export to depth. However, the annual primary production in the cryopelagic Canada Basin is 2 to 5 molC m-2yr-1 and is equivalent to that in the oligotrophic tropical gyre such as the Western Pacific Warm Pool where the FCorg, Cinorg and FSibio are a few orders of magnitude larger than those in the cryopelagic Canada Basin where the biological pump is essentially ineffective, primarily due to the deficiency of ballast particles in the upper layer. Thus, primary production POC is remineralized or turned into DOC within the surface layer instead of being quickly removed to deep waters. Total dry flux in the 3067 m trap was an order of magnitude larger than in the 120 and 200 m traps. In particular, lithogenic particle flux (FAl) and FCorg were about 18 and 2 times larger than in the upper ocean traps respectively. The Δ14C at 120 m indicated that the POC was mostly autochthonous. In contrast, the POC exported to 3067 m had an apparent 14C age of 1900 years

  19. Deep water masses and sediments are main compartments for polychlorinated biphenyls in the Arctic Ocean.

    Science.gov (United States)

    Sobek, Anna; Gustafsson, Örjan

    2014-06-17

    There is a wealth of studies of polychlorinated biphenyls (PCB) in surface water and biota of the Arctic Ocean. Still, there are no observation-based assessments of PCB distribution and inventories in and between the major Arctic Ocean compartments. Here, the first water column distribution of PCBs in the central Arctic Ocean basins (Nansen, Amundsen, and Makarov) is presented, demonstrating nutrient-like vertical profiles with 5-10 times higher concentrations in the intermediate and deep water masses than in surface waters. The consistent vertical profiles in all three Arctic Ocean basins likely reflect buildup of PCBs transported from the shelf seas and from dissolution and/or mineralization of settling particles. Combined with measurement data on PCBs in other Arctic Ocean compartments collected over the past decade, the total Arctic Ocean inventory of ∑7PCB was estimated to 182 ± 40 t (±1 standard error of the mean), with sediments (144 ± 40 t), intermediate (5 ± 1 t) and deep water masses (30 ± 2 t) storing 98% of the PCBs in the Arctic Ocean. Further, we used hydrographic and carbon cycle parametrizations to assess the main pathways of PCBs into and out of the Arctic Ocean during the 20th century. River discharge appeared to be the major pathway for PCBs into the Arctic Ocean with 115 ± 11 t, followed by ocean currents (52 ± 17 t) and net atmospheric deposition (30 ± 28 t). Ocean currents provided the only important pathway out of the Arctic Ocean, with an estimated cumulative flux of 22 ± 10 t. The observation-based inventory of ∑7PCB of 182 ± 40 t is consistent with the contemporary inventory based on cumulative fluxes for ∑7PCB of 173 ± 36 t. Information on the concentration and distribution of PCBs in the deeper compartments of the Arctic Ocean improves our understanding of the large-scale fate of POPs in the Arctic and may also provide a means to test and improve models used to assess the fate of organic pollutants in the Arctic.

  20. Ocean acidification research alongside extended continental shelf exploration in the western Arctic Ocean

    Science.gov (United States)

    Wynn, J. G.; Robbins, L. L.; Knorr, P. O.; Byrne, R. H.; Takahashi, T.; Onac, B. P.

    2013-12-01

    Research investments funded to fulfill the requirements of the UN Convention on the Law of the Sea in the western Arctic have allowed simultaneous acquisition of marine chemistry data, including baseline monitoring of changes in ocean acidification. Our participation in the Extended Continental Shelf cruises on the USCGC Healy in the western Arctic have allowed us to collect data focused on understanding processes driving rapid changes in seawater chemistry that result from increased oceanic uptake of CO2 (ocean acidification), increased freshwater runoff, changes in sea ice growth and decay processes and changes in biogeochemical processes. Carbonate mineral saturation data collected during HLY1002, HLY1102, and HLY1202 (summers 2010-2012) document undersaturation with respect to aragonite (Ωaragonite) in ~20% of the surface waters of the Canada and Makarov Basins, in direct association with areas of recently accelerated sea ice loss. Conservative tracer studies using salinity, stable oxygen isotopic composition, dissolved silica and barium augment this work by elucidating contributions from distinct water sources. These data show that while surface water in this entire area retains abundant freshwater from meteoric sources, it is freshwater additions from melting of multiyear sea ice which is most closely linked to the areas of aragonite undersaturation. Depth profiles from 20 oceanographic stations taken during the cruises show a ~100 m thick lens of Ωaragonite undersaturated water at ~150 m depth in the western Arctic, but not further north than 85°N. The surface waters in the Canada and Makarov Basins have pCO2 values much lower than the atmospheric pCO2 (~390 uatm), ranging between 350 μatm and 100 μatm, and are a strong sink for atmospheric CO2. The strong sink areas are found in the Chukchi Sea and western Beaufort shelf areas. These studies represent the frontiers of ocean acidification research in the western Arctic, in which baseline data have been

  1. Early ice retreat and ocean warming may induce copepod biogeographic boundary shifts in the Arctic Ocean

    Science.gov (United States)

    Feng, Zhixuan; Ji, Rubao; Campbell, Robert G.; Ashjian, Carin J.; Zhang, Jinlun

    2016-08-01

    Early ice retreat and ocean warming are changing various facets of the Arctic marine ecosystem, including the biogeographic distribution of marine organisms. Here an endemic copepod species, Calanus glacialis, was used as a model organism, to understand how and why Arctic marine environmental changes may induce biogeographic boundary shifts. A copepod individual-based model was coupled to an ice-ocean-ecosystem model to simulate temperature- and food-dependent copepod life history development. Numerical experiments were conducted for two contrasting years: a relatively cold and normal sea ice year (2001) and a well-known warm year with early ice retreat (2007). Model results agreed with commonly known biogeographic distributions of C. glacialis, which is a shelf/slope species and cannot colonize the vast majority of the central Arctic basins. Individuals along the northern boundaries of this species' distribution were most susceptible to reproduction timing and early food availability (released sea ice algae). In the Beaufort, Chukchi, East Siberian, and Laptev Seas where severe ocean warming and loss of sea ice occurred in summer 2007, relatively early ice retreat, elevated ocean temperature (about 1-2°C higher than 2001), increased phytoplankton food, and prolonged growth season created favorable conditions for C. glacialis development and caused a remarkable poleward expansion of its distribution. From a pan-Arctic perspective, despite the great heterogeneity in the temperature and food regimes, common biogeographic zones were identified from model simulations, thus allowing a better characterization of habitats and prediction of potential future biogeographic boundary shifts.

  2. The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean acidification impacts and potential feedbacks

    Directory of Open Access Journals (Sweden)

    N. R. Bates

    2009-11-01

    Full Text Available At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO2 on the order of −66 to −199 Tg C year−1 (1012 g C, contributing 5–14% to the global balance of CO2 sinks and sources. Because of this, the Arctic Ocean has an important influence on the global carbon cycle, with the marine carbon cycle and atmosphere-ocean CO2 exchanges sensitive to Arctic Ocean and global climate change feedbacks. In the near-term, further sea-ice loss and increases in phytoplankton growth rates are expected to increase the uptake of CO2 by Arctic Ocean surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO2 is expected to alter in response to environmental changes driven largely by climate. These changes are likely to continue to modify the physics, biogeochemistry, and ecology of the Arctic Ocean in ways that are not yet fully understood. In surface waters, sea-ice melt, river runoff, cooling and uptake of CO2 through air-sea gas exchange combine to decrease the calcium carbonate (CaCO3 mineral saturation states (Ω of seawater while seasonal phytoplankton primary production (PP mitigates this effect. Biological amplification of ocean acidification effects in subsurface waters, due to the remineralization of organic matter, is likely to reduce the ability of many species to produce CaCO3 shells or tests with profound implications for Arctic marine ecosystems

  3. Extreme changes of the Arctic Ocean during and after IPY 2007/2008

    OpenAIRE

    Timokhov, Leonid; Ashik, Igor; Dmitrenko, Igor; Hoelemann, Jens; Kassens, Heidemarie; Kirillov, Sergey; Polyakov, Igor; Sokolov, Vladimir

    2012-01-01

    Large-scale features of Arctic Ocean temperature and salinity distributions observed during 2007-2009 are described and discussed in the context of historical observation in order to document long-term variations. Oceanographic observations carried out in the frame of the International Polar Year (IPY 2007/2008) demonstrated unique conditions in the Arctic Ocean and seas during that period. For example, analyses of upper ocean temperature and salinity patterns 2007-2009 revealed an apparen...

  4. ACEX: A First Look at Arctic Ocean Cenozoic History

    Science.gov (United States)

    Moran, K.; Backman, J.

    2004-12-01

    The first Integrated Ocean Drilling Program mission specificplatform expedition (ACEX - Arctic Coring Expedition) drilled and recovered core from five holes at four sites through Cenozoic sediments draping the crest of the Lomonosov Ridge in the central Arctic Ocean. Coring continued into the underlying Cretaceous sedimentary bedrock. Sites are located only a few nautical miles apart along a single seismic line (AWI-91090), showing an identical and coherent Cenozoic seismostratigraphy. Preliminary results from shipboard investigations of core-catcher-based bio- and lithostratigraphy, pore water analyses and core logger data describe a thick (~160 m) middle Miocene through Pleistocene sequence that shows large amplitude, cyclic variability in the density, magnetic susceptibility and acoustic velocity of the sediments. Sediments are largely carbonate free. Pleistocene sedimentation rates are close to 3 cm/ka, whereas Pliocene sediments are by-and-large missing. A sharp change in physical properties at ~200 m defines the transition into a 200+ m thick Paleogene sequence that is initially dominated by large numbers of dinoflagellate cysts. The early Miocene, Oligocene and late Eocene appear to be largely missing in a hiatus. However, a 32 m thick interval separates the overlying middle Miocene from the underlying middle Eocene and presumably preserves some of the early Neogene and late Paleogene sections. Dinoflagellate cysts, diatoms, ebridians and silicoflagellates are common to abundant in the middle Eocene section, which bottoms in a spectacular layer showing massive occurrences of glochidia and massulae (megaspores) of the freshwater hydropterid fern Azolla (duckweed) at the early/middle Eocene boundary (~306 m), suggesting strongly reduced surface water salinity or perhaps even a brief episode of fresh water conditions at the surface. Biosilica is not present prior to the late early Eocene (~320 m). The (sub-) tropical dinoflagellate species Apectodinium augustum

  5. Meet the Arctic Benthos. Arctic Ocean Exploration--Grades 7-8. Benthic Invertebrate Groups in the Deep Arctic Ocean.

    Science.gov (United States)

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    This activity introduces students to major groups of invertebrates that have been found in other polar ocean expeditions and acquaints them with the feeding habits of these animals as a basis for making inferences about benthic communities and their connection to other components of the Artic Ocean ecosystem. The activity provides learning…

  6. Circulation in Vilkitsky Canyon in the eastern Arctic Ocean

    Science.gov (United States)

    Janout, Markus; Hölemann, Jens

    2016-04-01

    The eastern Arctic Ocean is characterized by steep continental slopes and vast shallow shelf seas that receive a large amount of riverine freshwater from some of the largest rivers on earth. The northwestern Laptev Sea is of particular interest, as it is a freshwater transport pathway for a swift surface-intensified current from the Kara Sea toward the Arctic Basin, as was recently highlighted by high-resolution model studies. The region features complex bathymetry including a narrow strait and a large submarine canyon, strong tides, polynyas and severe sea ice conditions throughout much of the year. A year-long mooring record as well as detailed hydrographic shipboard measurements resulted from summer expeditions to the area in 2013 and 2014, and now provide a detailed picture of the region's water properties and circulation. The hydrography is characterized by riverine Kara Sea freshwater near the surface in the southern part of the canyon, while warmer (~0°C) saline Atlantic-derived waters dominate throughout the canyon at depths >150m. Cold shelf-modified waters near the freezing point are found along the canyon edges. The mean flow at the 300 m-deep mooring location near the southern edge of the canyon is swift (30 cm/s) and oriented eastward near the surface as suggested by numerical models, while the deeper flow follows the canyon topography towards the north-east. Wind-driven deviations from the mean flow coincide with sudden changes in temperature and salinity. This study characterizes the general circulation in Vilkitsky Canyon and investigates its potential as a conduit for upwelling of Atlantic-derived waters from the Arctic Basin to the Laptev Sea shelf.

  7. Future scientific drilling in the Arctic Ocean: Key objectives, areas, and strategies

    Science.gov (United States)

    Stein, R.; Coakley, B.; Mikkelsen, N.; O'Regan, M.; Ruppel, C.

    2012-04-01

    In spite of the critical role of the Arctic Ocean in climate evolution, our understanding of the short- and long-term paleoceanographic and paleoclimatic history through late Mesozoic-Cenozoic times, as well as its plate-tectonic evolution, remains behind that from the other world's oceans. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the Arctic Coring Expedition - ACEX (or IODP Expedition 302), the first Mission Specific Platform (MSP) expedition within IODP, a new era in Arctic research began (Backman, Moran, Mayer, McInroy et al., 2006). ACEX proved that, with an intensive ice-management strategy, successful scientific drilling in the permanently ice-covered central Arctic Ocean is possible. ACEX is certainly a milestone in Arctic Ocean research, but - of course - further drilling activities are needed in this poorly studied ocean. Furthermore, despite the success of ACEX fundamental questions related to the long- and short-term climate history of the Arctic Ocean during Mesozoic-Cenozoic times remain unanswered. This is partly due to poor core recovery during ACEX and, especially, because of a major mid-Cenozoic hiatus in this single record. Since ACEX, a series of workshops were held to develop a scientific drilling strategy for investigating the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system: - "Arctic Ocean History: From Speculation to Reality" (Bremerhaven/Germany, November 2008); - "Overcoming barriers to Arctic Ocean scientific drilling: the site survey challenge" (Copenhagen/Denmark, November 2011); - Circum-Arctic shelf/upper continental slope scientific drilling workshop on "Catching Climate Change in Progress" (San Francisco/USA, December 2011); - "Coordinated Scientific Drilling in the Beaufort Sea: Addressing

  8. An Improved 20-Year Arctic Ocean Altimetric Sea Level Data Record

    DEFF Research Database (Denmark)

    Cheng, Yongcun; Andersen, Ole Baltazar; Knudsen, Per

    2015-01-01

    For ocean and climate research, it is essential to get long-term altimetric sea level data that is as accurate as possible. However, the accuracy of the altimetric data is frequently degraded in the interior of the Arctic Ocean due to the presence of seasonal or permanent sea ice. We have...... reprocessed ERS-1/2/Envisat satellite altimetry to develop an improved 20-year sea level dataset for the Arctic Ocean. We have developed both an along-track dataset and three-day gridded sea level anomaly (SLA) maps from September 1992 to April 2012. A major improvement in data coverage was gained...... estimation of sea level changes from satellite altimetry in the Arctic Ocean. The reprocessed dataset exhibit a mean sea level trend of 2.1 +/- 1.3mm/year (without Glacial Isostatic Adjustment correction) covering the Arctic Ocean between 66 degrees N and 82 degrees N with significant higher spatial...

  9. Meteorological conditions in the central Arctic summer during the Arctic Summer Cloud Ocean Study (ASCOS

    Directory of Open Access Journals (Sweden)

    M. Tjernström

    2012-08-01

    Full Text Available Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as the Arctic Summer Cloud-Ocean Study (ASCOS, described here. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this.

    To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean: the AOE-96, SHEBA and AOE-2001 expeditions.

    We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of surface-shear and

  10. Ocean currents shape the microbiome of Arctic marine sediments.

    Science.gov (United States)

    Hamdan, Leila J; Coffin, Richard B; Sikaroodi, Masoumeh; Greinert, Jens; Treude, Tina; Gillevet, Patrick M

    2013-04-01

    Prokaryote communities were investigated on the seasonally stratified Alaska Beaufort Shelf (ABS). Water and sediment directly underlying water with origin in the Arctic, Pacific or Atlantic oceans were analyzed by pyrosequencing and length heterogeneity-PCR in conjunction with physicochemical and geographic distance data to determine what features structure ABS microbiomes. Distinct bacterial communities were evident in all water masses. Alphaproteobacteria explained similarity in Arctic surface water and Pacific derived water. Deltaproteobacteria were abundant in Atlantic origin water and drove similarity among samples. Most archaeal sequences in water were related to unclassified marine Euryarchaeota. Sediment communities influenced by Pacific and Atlantic water were distinct from each other and pelagic communities. Firmicutes and Chloroflexi were abundant in sediment, although their distribution varied in Atlantic and Pacific influenced sites. Thermoprotei dominated archaea in Pacific influenced sediments and Methanomicrobia dominated in methane-containing Atlantic influenced sediments. Length heterogeneity-PCR data from this study were analyzed with data from methane-containing sediments in other regions. Pacific influenced ABS sediments clustered with Pacific sites from New Zealand and Chilean coastal margins. Atlantic influenced ABS sediments formed another distinct cluster. Density and salinity were significant structuring features on pelagic communities. Porosity co-varied with benthic community structure across sites and methane did not. This study indicates that the origin of water overlying sediments shapes benthic communities locally and globally and that hydrography exerts greater influence on microbial community structure than the availability of methane.

  11. Photoheterotrophic microbes in the Arctic Ocean in summer and winter.

    Science.gov (United States)

    Cottrell, Matthew T; Kirchman, David L

    2009-08-01

    Photoheterotrophic microbes, which are capable of utilizing dissolved organic materials and harvesting light energy, include coccoid cyanobacteria (Synechococcus and Prochlorococcus), aerobic anoxygenic phototrophic (AAP) bacteria, and proteorhodopsin (PR)-containing bacteria. Our knowledge of photoheterotrophic microbes is largely incomplete, especially for high-latitude waters such as the Arctic Ocean, where photoheterotrophs may have special ecological relationships and distinct biogeochemical impacts due to extremes in day length and seasonal ice cover. These microbes were examined by epifluorescence microscopy, flow cytometry, and quantitative PCR (QPCR) assays for PR and a gene diagnostic of AAP bacteria (pufM). The abundance of AAP bacteria and PR-containing bacteria decreased from summer to winter, in parallel with a threefold decrease in the total prokaryotic community. In contrast, the abundance of Synechococcus organisms did not decrease in winter, suggesting that their growth was supported by organic substrates. Results from QPCR assays revealed no substantial shifts in the community structure of AAP bacteria and PR-containing bacteria. However, Arctic PR genes were different from those found at lower latitudes, and surprisingly, they were not similar to those in Antarctic coastal waters. Photoheterotrophic microbes appear to compete successfully with strict heterotrophs during winter darkness below the ice, but AAP bacteria and PR-containing bacteria do not behave as superior competitors during the summer.

  12. Physical characteristics of summer sea ice across the Arctic Ocean

    Science.gov (United States)

    Tucker, W. B.; Gow, A.J.; Meese, D.A.; Bosworth, H.W.; Reimnitz, E.

    1999-01-01

    Sea ice characteristics were investigated during July and August on the 1994 transect across the Arctic Ocean. Properties examined from ice cores included salinity, temperature, and ice structure. Salinities measured near zero at the surface, increasing to 3-4??? at the ice-water interface. Ice crystal texture was dominated by columnar ice, comprising 90% of the ice sampled. Surface albedos of various ice types, measured with radiometers, showed integrated shortwave albedos of 0.1 to 0.3 for melt ponds, 0.5 for bare, discolored ice, and 0.6 to 0.8 for a deteriorated surface or snow-covered ice. Aerial photography was utilized to document the distribution of open melt ponds, which decreased from 12% coverage of the ice surface in late July at 76??N to almost none in mid-August at 88??N. Most melt ponds were shallow, and depth bore no relationship to size. Sediment was pervasive from the southern Chukchi Sea to the north pole, occurring in bands or patches. It was absent in the Eurasian Arctic, where it had been observed on earlier expeditions. Calculations of reverse trajectories of the sediment-bearing floes suggest that the southernmost sediment was entrained during ice formation in the Beaufort Sea while more northerly samples probably originated in the East Siberian Sea, some as far west as the New Siberian Islands.

  13. Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean

    Science.gov (United States)

    2015-06-12

    1 Title: Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean POP: 6/15/2014–6/14/2015 CDRL A002: Progress Report Technical...through April 30, 2015: $214,960 Estimate to complete: $71,245 ABSTRACT With the sea ice cover in the Arctic Ocean declining, the more...14-06-2015 4. TITLE AND SUBTITLE Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  14. Exploring the role of shelf sediments in the Arctic Ocean in determining the Arctic contamination potential of neutral organic contaminants.

    Science.gov (United States)

    Armitage, James M; Choi, Sung-Deuk; Meyer, Torsten; Brown, Trevor N; Wania, Frank

    2013-01-15

    The main objective of this study was to model the contribution of shelf sediments in the Arctic Ocean to the total mass of neutral organic contaminants accumulated in the Arctic environment using a standardized emission scenario for sets of hypothetical chemicals and realistic emission estimates (1930-2100) for polychlorinated biphenyl congener 153 (PCB-153). Shelf sediments in the Arctic Ocean are shown to be important reservoirs for neutral organic chemicals across a wide range of partitioning properties, increasing the total mass in the surface compartments of the Arctic environment by up to 3.5-fold compared to simulations excluding this compartment. The relative change in total mass for hydrophobic organic chemicals with log air-water partition coefficients ≥0 was greater than for chemicals with properties similar to typical POPs. The long-term simulation of PCB-153 generated modeled concentrations in shelf sediments in reasonable agreement with available monitoring data and illustrate that the relative importance of shelf sediments in the Arctic Ocean for influencing surface ocean concentrations (and therefore exposure via the pelagic food web) is most pronounced once primary emissions are exhausted and secondary sources dominate. Additional monitoring and modeling work to better characterize the role of shelf sediments for contaminant fate is recommended.

  15. Methyl iodine over oceans from the Arctic Ocean to the maritime Antarctic

    Science.gov (United States)

    Hu, Qihou; Xie, Zhouqing; Wang, Xinming; Yu, Juan; Zhang, Yanli

    2016-05-01

    Studies about methyl iodide (CH3I), an important atmospheric iodine species over oceans, had been conducted in some maritime regions, but the understanding of the spatial distribution of CH3I on a global scale is still limited. In this study, we reports atmospheric CH3I over oceans during the Chinese Arctic and Antarctic Research Expeditions. CH3I varied considerably with the range of 0.17 to 2.9 pptv with absent of ship emission. The concentration of CH3I generally decreased with increasing latitudes, except for higher levels in the middle latitudes of the Northern Hemisphere than in the low latitudes. For sea areas, the Norwegian Sea had the highest CH3I concentrations with a median of 0.91 pptv, while the Central Arctic Ocean had the lowest concentrations with all values below 0.5 pptv. CH3I concentration over oceans was affected by many parameters, including sea surface temperature, salinity, dissolved organic carbon, biogenic emissions and input from continents, with distinctive dominant factor in different regions, indicating complex biogeochemical processes of CH3I on a global scale.

  16. Synechococcus in the Atlantic gateway to the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Maria Lund Paulsen

    2016-10-01

    Full Text Available Increasing temperatures, with pronounced effects at high latitudes, have raised questions about potential changes in species composition, as well as possible increased importance of small-celled phytoplankton in marine systems. In this study, we mapped out one of the smallest and globally most widespread primary producers, the picocyanobacterium Synechococcus, within the Atlantic inflow to the Arctic Ocean. In contrast to the general understanding that Synechococcus is almost absent in polar oceans due to low temperatures, we encountered high abundances (up to 21,000 cells mL-1 at 79 °N, and documented their presence as far north as 82.5 °N. Covering an annual cycle in 2014, we found that during autumn and winter, Synechococcus was often more abundant than picoeukaryotes, which usually dominate the picophytoplankton communities in the Arctic. Synechococcus community composition shifted from a quite high genetic diversity during the spring bloom to a clear dominance of two specific operational taxonomic units (OTUs in autumn and winter. We observed abundances higher than 1,000 cells mL-1 in water colder than 2 °C at seven distinct stations and size-fractionation experiments demonstrated a net growth of Synechococcus at 2 °C in the absence of nano-sized grazers at certain periods of the year. Phylogenetic analysis of petB sequences demonstrated that these high latitude Synechococcus group within the previously described cold-adapted clades I and IV, but also contributed to unveil novel genetic diversity, especially within clade I.

  17. Response of halocarbons to ocean acidification in the Arctic

    Directory of Open Access Journals (Sweden)

    F. E. Hopkins

    2013-04-01

    Full Text Available The potential effect of ocean acidification (OA on seawater halocarbons in the Arctic was investigated during a mesocosm experiment in Spitsbergen in June–July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine ~ 50 m3 mesocosms were studied under a range of pCO2 treatments from ~ 185 μatm to ~ 1420 μatm. In general, the response of halocarbons to pCO2 was subtle, or undetectable. A large number of significant correlations with a range of biological parameters (chlorophyll a, microbial plankton community, phytoplankton pigments were identified, indicating a biological control on the concentrations of halocarbons within the mesocosms. The temporal dynamics of iodomethane (CH3I alluded to active turnover of this halocarbon in the mesocosms and strong significant correlations with biological parameters suggested a biological source. However, despite a pCO2 effect on various components of the plankton community, and a strong association between CH3I and biological parameters, no effect of pCO2 was seen in CH3I. Diiodomethane (CH2I2 displayed a number of strong relationships with biological parameters. Furthermore, the concentrations, the rate of net production and the sea-to-air flux of CH2I2 showed a significant positive response to pCO2. There was no clear effect of pCO2 on bromocarbon concentrations or dynamics. However, periods of significant net loss of bromoform (CHBr3 were found to be concentration-dependent, and closely correlated with total bacteria, suggesting a degree of biological consumption of this halocarbon in Arctic waters. Although the effects of OA on halocarbon concentrations were marginal, this study provides invaluable information on the production and cycling of halocarbons in a region of the world's oceans likely to experience rapid environmental change in the coming decades.

  18. 77 FR 2513 - Draft Environmental Impact Statement for Effects of Oil and Gas Activities in the Arctic Ocean

    Science.gov (United States)

    2012-01-18

    ... Effects of Oil and Gas Activities in the Arctic Ocean AGENCY: National Marine Fisheries Service (NMFS... the Effects of Oil and Gas Activities in the Arctic Ocean.'' Based on several written requests.../pr/permits/eis/arctic.htm . FOR FURTHER INFORMATION CONTACT: Candace Nachman, Jolie Harrison,...

  19. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    Science.gov (United States)

    Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  20. Arctic Ocean sea ice drift origin derived from artificial radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Camara-Mor, P., E-mail: patricia.camara@uab.es [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Masque, P. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Garcia-Orellana, J. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Cochran, J.K. [School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Mas, J.L. [Dpto. de Fisica Aplicada, Universidad de Sevilla, 41012, Seville. Spain (Spain); Chamizo, E. [Centro Nacional de Aceleradores (CNA), Avd. Thomas Alva Edison 7, Isla de la Cartuja, E-41092, Seville (Spain); Hanfland, C. [Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven (Germany)

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of {sup 137}Cs and {sup 239,240}Pu activities and the {sup 240}Pu/{sup 239}Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The {sup 240}Pu/{sup 239}Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the {sup 240}Pu/{sup 239}Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the {sup 137}Cs and {sup 239,240}Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  1. A global mass balance analysis of the source of perfluorocarboxylic acids in the Arctic Ocean.

    Science.gov (United States)

    Wania, Frank

    2007-07-01

    Whereas the pervasive and abundant presence of perfluorinated carboxylic acids (PFCAs) in the Arctic marine food chain is clearly established, their origin and transport pathway into the Arctic Ocean are not. Either the atmospheric oxidation of volatile precursor compounds, such as the fluorotelomer alcohols (FTOHs), or the long-range oceanic transport of directly emitted PFCAs is seen as contributing the bulk of the PFCA input to the Arctic. Here simulations with the zonally averaged global fate and transport model Globo-POP, in combination with historical emission estimates for FTOHs and perfluorooctanoic acid (PFOA), are used to evaluate the relative efficiency and importance of the two transport pathways. Estimates of the emission-independent Arctic Contamination Potential reveal that the oceanic transport of directly emitted PFCAs is more than 10-fold more efficient than the atmospheric degradation of FTOHs in delivering PFCAs to the Arctic, mostly because of the low yield of the reaction. The cumulative historic emissions of FTOHs are lower than those estimated for PFOA alone by a factor of 2-3, further limiting the contribution that precursor oxidation makes to the total PFCAs load in the Arctic Ocean. Accordingly, when fed only with FTOH emissions, the model predicts FTOH air concentrations in agreement with the reported measurements, but yields Arctic seawater concentrations for the PFOA that are 2 orders of magnitude too low. Whereas ocean transport is thus very likely the dominant pathway of PFOA into the Arctic Ocean, the major transport route of longer chain PFCAs depends on the size of their direct emissions relative to those of 10:2 FTOH. The predicted time course of Arctic seawater concentrations is very similar for directly emitted and atmospherically generated PFCAs, implying that neither past doubling times of PFCA concentrations in Arctic marine mammals nor any future time trends are likely to resolve the question of the dominant source of PFCAs.

  2. Dredged bedrock samples from the Amerasia Basin, Arctic Ocean

    Science.gov (United States)

    Brumley, K. J.; Mukasa, S. B.; O'Brien, T. M.; Mayer, L. A.; Chayes, D. N.

    2013-12-01

    Between 2008-2012, as part of the U.S. Extended Continental Shelf project in the Amerasia Basin, Arctic Ocean, 17 dredges were successfully collected sampling the first rock outcrops in the Chukchi Borderland and surrounding regions for the purpose of describing the geologic nature of the bathymetric features in this area. Multiple lines of evidence indicate that the specimens were collected from submarine rock exposures and were not samples of ice rafted debris, common in the ice covered waters of the Arctic Ocean. Using the USCGC Healy, each dredge was collected along very steep slopes (>35 degrees) measured with high resolution multibeam swath bathymety data. Each haul yielded samples of similar lithologies and identical metamorphic grade with manganese crusts on the surfaces exposed to seawater and fresh surfaces where the rocks were broken from outcrop. High tension pulls on the dredge line also indicated sampling of bedrock exposures. Dredged samples from a normal fault scarp in the central Chukchi Borderland consisted of Silurian (c. 430 Ma) orthogneisses that intruded older (c. 487-500 Ma) gabbros and luecogranties that were all metamorphosed to amphibolite grade (Brumley et al., 2011). Samples from the northern Northwind Ridge consisted of metasediments (greenschist facies) interpreted to have been deposited in a proximal arc setting with detrital zircon U-Pb age peaks at 434, 980 Ma with lesser peaks between 500-600, 1100-2000 Ma, and rare 2800 Ma grains (Brumley et al, 2010). Other dredges in the region of the Northwind Ridge yielded deformed and metamorphosed calcareous sandstones and low-grade phyllites (O'Brien et al., 2013). Taken together these rocks indicate a relationship to the Pearya Terrane of northern Ellesmere Island and S.W. Svalbard that were thought to represent a Cambro-Ordovician volcanic arc terrane that was involved in Caledonian orogenesis (Brumley et al., 2011). These findings constrain plate tectonic reconstruction models and bring

  3. Climate Change and China as a Global Emerging Regulatory Sea Power in the Arctic Ocean

    DEFF Research Database (Denmark)

    Cassotta, Sandra; Hossain, Kamrul; Ren, Jingzheng

    2015-01-01

    on the Law of the Sea (UNCLOS) and the Arctic Council (AC) are taken into consideration under climate change effects, to assess how global legal frameworks and institutions can deal with China’s strategy in the Arctic Ocean. China’s is moving away from its role as “humble power” to one of “informal...

  4. Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation.

    Science.gov (United States)

    Jakobsson, Martin; Nilsson, Johan; Anderson, Leif; Backman, Jan; Björk, Göran; Cronin, Thomas M; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Barrientos Macho, Natalia; Cherniykh, Denis; Coxall, Helen; Eriksson, Björn; Flodén, Tom; Gemery, Laura; Gustafsson, Örjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

    2016-01-18

    The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼ 140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

  5. Moderate-resolution sea surface temperature data for the Arctic Ocean Ecoregions

    Science.gov (United States)

    Sea surface temperature (SST) is an important environmental characteristic in determining the suitability and sustainability of habitats for marine organisms. Of particular interest is the fate of the Arctic Ocean, which provides critical habitat to commercially important fish (M...

  6. Recent Changes in Arctic Ocean Sea Ice Motion Associated with the North Atlantic Oscillation

    Science.gov (United States)

    Kwok, R.

    1999-01-01

    Examination of a new ice motion dataset of the Arctic Ocean over a recent eighteen year period (1978-1996) reveals patterns of variability that can be linked directly to the North Atlantic Oscillation.

  7. Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation

    Science.gov (United States)

    Jakobsson, Martin; Nilsson, Johan; Anderson, Leif G.; Backman, Jan; Bjork, Goran; Cronin, Thomas M.; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Macho, Natalia Barrientos; Cherniykh, Dennis; Coxall, Helen; Eriksson, Bjorn; Floden, Tom; Gemery, Laura; Gustafsson, Orjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

    2016-01-01

    The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (~140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

  8. Recent Arctic Ocean sea ice loss triggers novel fall phytoplankton blooms

    Science.gov (United States)

    Ardyna, Mathieu; Babin, Marcel; Gosselin, Michel; Devred, Emmanuel; Rainville, Luc; Tremblay, Jean-Éric

    2014-09-01

    Recent receding of the ice pack allows more sunlight to penetrate into the Arctic Ocean, enhancing productivity of a single annual phytoplankton bloom. Increasing river runoff may, however, enhance the yet pronounced upper ocean stratification and prevent any significant wind-driven vertical mixing and upward supply of nutrients, counteracting the additional light available to phytoplankton. Vertical mixing of the upper ocean is the key process that will determine the fate of marine Arctic ecosystems. Here we reveal an unexpected consequence of the Arctic ice loss: regions are now developing a second bloom in the fall, which coincides with delayed freezeup and increased exposure of the sea surface to wind stress. This implies that wind-driven vertical mixing during fall is indeed significant, at least enough to promote further primary production. The Arctic Ocean seems to be experiencing a fundamental shift from a polar to a temperate mode, which is likely to alter the marine ecosystem.

  9. International Bathymetric Chart of the Arctic Ocean, Version 3.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — IBCAO Version 3.0 represents the largest improvement since 1999 taking advantage of new data sets collected by the circum-Arctic nations, opportunistic data...

  10. Retention of ice-associated amphipods: possible consequences for an ice-free Arctic Ocean.

    Science.gov (United States)

    Berge, J; Varpe, O; Moline, M A; Wold, A; Renaud, P E; Daase, M; Falk-Petersen, S

    2012-12-23

    Recent studies predict that the Arctic Ocean will have ice-free summers within the next 30 years. This poses a significant challenge for the marine organisms associated with the Arctic sea ice, such as marine mammals and, not least, the ice-associated crustaceans generally considered to spend their entire life on the underside of the Arctic sea ice. Based upon unique samples collected within the Arctic Ocean during the polar night, we provide a new conceptual understanding of an intimate connection between these under-ice crustaceans and the deep Arctic Ocean currents. We suggest that downwards vertical migrations, followed by polewards transport in deep ocean currents, are an adaptive trait of ice fauna that both increases survival during ice-free periods of the year and enables re-colonization of sea ice when they ascend within the Arctic Ocean. From an evolutionary perspective, this may have been an adaptation allowing success in a seasonally ice-covered Arctic. Our findings may ultimately change the perception of ice fauna as a biota imminently threatened by the predicted disappearance of perennial sea ice.

  11. Is the "Atlantification" of the Arctic Ocean extending?

    Science.gov (United States)

    Ivanov, V.; Alexeev, V. A.; Koldunov, N. V.; Repina, I.; Sandø, A. B.; Smedsrud, L. H.; Smirnov, A.

    2015-12-01

    We present recent observation and modelling results, which suggest that retreat of the sea-ice edge in the Atlantic sector of the Arctic Ocean over several recent years may be an indication of the growing influence of Atlantic Water on the hydrographic regime ("Atlantification"). The 'memory' of ice-depleted conditions in summer is transferred to the fall season, through excess heat content in the upper mixed layer, which in turn transfers to mid-winter via thinner and younger ice. This thinner ice is more fragile and mobile, thus facilitating the formation of polynyas and leads. When openings in ice cover form along the Atlantic Water pathway, weak density stratification at the mixed layer base supports the development of thermohaline convection, which further entrains warm and salty water from deeper layers. Convection-induced upward heat flux from the Atlantic layer retards ice formation, either keeping ice thickness low or blocking ice formation entirely. The joint analysis of observations and modelling data is performed north-east of Svalbard where the top hundred meters of Atlantic inflow through the Fram Strait cools and freshens rapidly. Complementary research methods, including statistical analyses of observations and numerical modelling, support our basic "Atlantification" concept. A general conclusion from the analysis performed is that the recently observed retreat of sea ice northeast of Svalbard in winter may be explained by the positive feedback between summer ice decay and the growing influence of oceanic heat on a seasonal time scale.

  12. Ecology of the rare microbial biosphere of the Arctic Ocean.

    Science.gov (United States)

    Galand, Pierre E; Casamayor, Emilio O; Kirchman, David L; Lovejoy, Connie

    2009-12-29

    Understanding the role of microbes in the oceans has focused on taxa that occur in high abundance; yet most of the marine microbial diversity is largely determined by a long tail of low-abundance taxa. This rare biosphere may have a cosmopolitan distribution because of high dispersal and low loss rates, and possibly represents a source of phylotypes that become abundant when environmental conditions change. However, the true ecological role of rare marine microorganisms is still not known. Here, we use pyrosequencing to describe the structure and composition of the rare biosphere and to test whether it represents cosmopolitan taxa or whether, similar to abundant phylotypes, the rare community has a biogeography. Our examination of 740,353 16S rRNA gene sequences from 32 bacterial and archaeal communities from various locations of the Arctic Ocean showed that rare phylotypes did not have a cosmopolitan distribution but, rather, followed patterns similar to those of the most abundant members of the community and of the entire community. The abundance distributions of rare and abundant phylotypes were different, following a log-series and log-normal model, respectively, and the taxonomic composition of the rare biosphere was similar to the composition of the abundant phylotypes. We conclude that the rare biosphere has a biogeography and that its tremendous diversity is most likely subjected to ecological processes such as selection, speciation, and extinction.

  13. NODC Standard Product: International ocean atlas Volume 6 - Zooplankton of the Arctic Seas 2002 (NODC Accession 0098570)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical and biological data for the Arctic and sub-Arctic regions extending from the Barents Sea to the Northwest Pacific, sampled during 25 scientific cruises for...

  14. North Pole Environmental Observatory CTD surveys: Springtime temperature and salinity measurements in the Arctic Ocean by aircraft, 2000 - 2008 (NODC Accession 0057592)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The investigators propose to take annual springtime, large-scale airborne surveys of the Arctic Ocean. These surveys will be in two regions: the central Arctic Ocean...

  15. Upper Arctic Ocean velocity structure from in-situ observations

    Science.gov (United States)

    Recinos, Beatriz; Rabe, Benjamin; Schauer, Ursula

    2016-04-01

    The gross circulation of the upper and intermediate layers of the Arctic Ocean has been inferred from water mass properties: the mixed layer, containing fresh water from the shelf seas, travels from Siberia towards the Atlantic sector, and the saline and warm layer of Atlantic origin below, follows cyclonic pathways along topographic features. Direct observations of the flow below the sea ice are, however, sparse and difficult to obtain. This research presents the analysis of a unique time series/section of in situ velocity measurements obtained by a drifting ice-tethered platform in the Transpolar Drift near the North Pole. Two instruments were used to obtain in situ measurements of velocity, temperature, salinity and pressure: an Ice-tethered Acoustic Current profiler (ITAC) and an Ice-tethered Profiler (ITP). Both systems were deployed in the Amundsen basin, during the Arctic Ocean expedition ARK XXII/2 of the German Research Vessel Polarstern in September 2007. The systems transmitted profile data from the 14th of September to the 29th of November 2007 and covered a maximum depth range of 23 to 400 m. The results are compared to observations by a shipboard Acoustic Doppler Current Profiler (ADCP) from the 2011 Polarstern expedition ARK-XXVI/3, and wind and ice concentration from satellite reanalysis products. The data set allows an overview of the upper and intermediate circulation along the Lomonosov Ridge. Near-surface velocity and ice drift obtained by the ITAC unit are consistent with the Transpolar Drift Current. Ekman transports calculated from the observed ice drift and assumed ice-ocean drag behaviour suggest that Ekman dynamics influenced velocities at depths greater than the Ekman layer. Direct velocity observations in combination with water mass analyses from the temperature and salinity data, suggest the existence of a current along the Eurasian side of the Lomonosov Ridge within the warm Atlantic layer below the cold halocline. At those depths

  16. Ecosystem model intercomparison of under-ice and total primary production in the Arctic Ocean

    OpenAIRE

    Jin, Meibing; Popova, Ekaterina E.; Zhang, Jinlun; Ji, Rubao; Pendleton, Daniel; Varpe, Øystein; Yool, Andrew; Lee, Younjoo J.

    2016-01-01

    Previous observational studies have found increasing primary production (PP) in response to declining sea ice cover in the Arctic Ocean. In this study, under-ice PP was assessed based on three coupled ice-ocean-ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project. All models showed good agreement with under-ice measurements of surface chlorophyll-a concentration and vertically integrated PP rates during the main under-ice production perio...

  17. Organophosphate Ester Flame Retardants and Plasticizers in Ocean Sediments from the North Pacific to the Arctic Ocean.

    Science.gov (United States)

    Ma, Yuxin; Xie, Zhiyong; Lohmann, Rainer; Mi, Wenying; Gao, Guoping

    2017-04-04

    The presence of organophosphate ester (OPE) flame retardants and plasticizers in surface sediment from the North Pacific to Arctic Ocean was observed for the first time during the fourth National Arctic Research Expedition of China in the summer of 2010. The samples were analyzed for three halogenated OPEs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(dichloroisopropyl) phosphate], three alkylated OPEs [triisobutyl phosphate (TiBP), tri-n-butyl phosphate, and tripentyl phosphate], and triphenyl phosphate. Σ7OPEs (total concentration of the observed OPEs) was in the range of 159-4658 pg/g of dry weight. Halogenated OPEs were generally more abundant than the nonhalogenated OPEs; TCEP and TiBP dominated the overall concentrations. Except for that of the Bering Sea, Σ7OPEs values increased with increasing latitudes from Bering Strait to the Central Arctic Ocean, while the contributions of halogenated OPEs (typically TCEP and TCPP) to the total OPE profile also increased from the Bering Strait to the Central Arctic Ocean, indicating they are more likely to be transported to the remote Arctic. The median budget of 52 (range of 17-292) tons for Σ7OPEs in sediment from the Central Arctic Ocean represents only a very small amount of their total production volume, yet the amount of OPEs in Arctic Ocean sediment was significantly larger than the sum of polybrominated diphenyl ethers (PBDEs) in the sediment, indicating they are equally prone to long-range transport away from source regions. Given the increasing level of production and usage of OPEs as substitutes of PBDEs, OPEs will continue to accumulate in the remote Arctic.

  18. USGS Arctic Ocean Carbon Cruise 2012: Field Activity L-01-12-AR to collect carbon data in the Arctic Ocean, August-September 2012

    Science.gov (United States)

    Robbins, Lisa L.; Wynn, Jonathan; Knorr, Paul O.; Onac, Bogdan; Lisle, John T.; McMullen, Katherine Y.; Yates, Kimberly K.; Byrne, Robert H.; Liu, Xuewu

    2014-01-01

    From August 25 to September 27, 2012, the United States Coast Guard Cutter (USCGC) Healy was part of an Extended Continental Shelf Project to determine the limits of the extended continental shelf in the Arctic. On a non-interference basis, a USGS ocean acidification team participated on the cruise to collect baseline water data in the Arctic. The collection of data extended from coastal waters near Barrow, Alaska, to 83°2'N., -175°36'W., and southward back to coastal waters near Barrow and on to Dutch Harbor, Alaska. As a consequence, a number of hypotheses were tested and questions asked associated with ocean acidification, including:

  19. Petroleum prospectivity of the Canada Basin, Arctic Ocean

    Science.gov (United States)

    Grantz, A.; Hart, P.E.

    2012-01-01

    Reconnaissance seismic reflection data indicate that Canada Basin is a >700,000 sq. km. remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed across the northern part of the Amerasia Basin between about 127 and 89-83.5 Ma. Canada Basin was filled by Early Jurassic to Holocene detritus from the Beaufort-Mackenzie Deltaic System, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. The basin contains roughly 5 or 6 million cubic km of sediment. Three fourths or more of this volume generates low amplitude seismic reflections, interpreted to represent hemipelagic deposits, which contain lenses to extensive interbeds of moderate amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits.Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin is correlative with stratigraphic sequences in these areas that contain intervals of hydrocarbon source rocks. In addition, worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas windows. Structural, stratigraphic and combined structural and stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin, and at least one of these contains bright spots. However, deep water (to almost 4000 m), remoteness from harbors and markets, and thick accumulations of seasonal to permanent sea ice (until its possible removal by global warming later this century) will require the discovery of very large deposits for commercial success in most parts of Canada Basin. ?? 2011 Elsevier Ltd.

  20. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean.

    Science.gov (United States)

    Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-20

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (Arctic Ocean (79-90 °N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85 °N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  1. A model study of the first ventilated regime of the Arctic Ocean during the early Miocene

    Directory of Open Access Journals (Sweden)

    Bijoy Thompson

    2012-07-01

    Full Text Available The tectonic opening of Fram Strait during the Neogene was a significant geological event that transferred the Arctic Ocean from a poorly ventilated enclosed basin, with weak exchange with the North Atlantic, to a fully ventilated “ocean stage”. Previous tectonic and physical oceanographic analyses suggest that the early Miocene Fram Strait was likely several times narrower and less than half as deep as the present-day 400 km wide and 2550 m deep strait. Here we use an ocean general circulation model with a passive age tracer included to further address the effect of the Fram Strait opening on the early Miocene Arctic Ocean circulation. The model tracer age exhibits strong spatial gradient between the two major Arctic Ocean deep basins: the Eurasian and Amerasian basins. There is a two-layer stratification and the exchange flow through Fram Strait shows a bi-layer structure with a low salinity outflow from the Arctic confined to a relatively thin upper layer and a saline inflow from the North Atlantic below. Our study suggests that although Fram Strait was significantly narrower and shallower during early Miocene, and the ventilation mechanism quite different in our model, the estimated ventilation rates are comparable to the chemical tracer estimates in the present-day Arctic Ocean. Since we achieved ventilation of the Arctic Ocean with a prescribed Fram Strait width of 100 km and sill depth of 1000 m, ventilation may have preceded the timing of a full ocean depth connection between the Arctic Ocean and North Atlantic established through seafloor spreading and the development of the Lena Trough.

  2. Arctic-HYCOS: a Large Sample observing system for estimating freshwater fluxes in the drainage basin of the Arctic Ocean

    Science.gov (United States)

    Pietroniro, Al; Korhonen, Johanna; Looser, Ulrich; Hardardóttir, Jórunn; Johnsrud, Morten; Vuglinsky, Valery; Gustafsson, David; Lins, Harry F.; Conaway, Jeffrey S.; Lammers, Richard; Stewart, Bruce; Abrate, Tommaso; Pilon, Paul; Sighomnou, Daniel; Arheimer, Berit

    2015-04-01

    The Arctic region is an important regulating component of the global climate system, and is also experiencing a considerable change during recent decades. More than 10% of world's river-runoff flows to the Arctic Ocean and there is evidence of changes in its fresh-water balance. However, about 30% of the Arctic basin is still ungauged, with differing monitoring practices and data availability from the countries in the region. A consistent system for monitoring and sharing of hydrological information throughout the Arctic region is thus of highest interest for further studies and monitoring of the freshwater flux to the Arctic Ocean. The purpose of the Arctic-HYCOS project is to allow for collection and sharing of hydrological data. Preliminary 616 stations were identified with long-term daily discharge data available, and around 250 of these already provide online available data in near real time. This large sample will be used in the following scientific analysis: 1) to evaluate freshwater flux to the Arctic Ocean and Seas, 2) to monitor changes and enhance understanding of the hydrological regime and 3) to estimate flows in ungauged regions and develop models for enhanced hydrological prediction in the Arctic region. The project is intended as a component of the WMO (World Meteorological Organization) WHYCOS (World Hydrological Cycle Observing System) initiative, covering the area of the expansive transnational Arctic basin with participation from Canada, Denmark, Finland, Iceland, Norway, Russian Federation, Sweden and United States of America. The overall objective is to regularly collect, manage and share high quality data from a defined basic network of hydrological stations in the Arctic basin. The project focus on collecting data on discharge and possibly sediment transport and temperature. Data should be provisional in near-real time if available, whereas time-series of historical data should be provided once quality assurance has been completed. The

  3. Response of halocarbons to ocean acidification in the Arctic

    Directory of Open Access Journals (Sweden)

    F. E. Hopkins

    2012-07-01

    Full Text Available The potential effect of ocean acidification (OA on seawater halocarbons in the Arctic was investigated during a~mesocosm experiment in Spitsbergen in June–July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine ~50 m3 mesocosms were studied under a range of pCO2 treatments from ~185 μatm to ~1420 μatm. In general, the response of halocarbons to pCO2 was subtle, or undetectable. A large number of significant correlations with a range of biological parameters (chlorophyll a, microbial plankton community, phytoplankton pigments were identified, indicating a biological control on the concentrations of halocarbons within the mesocosms. The temporal dynamics of iodomethane (CH3I alluded to active turnover of this halocarbon in the mesocosms and strong significant correlations with biological parameters suggested a biological source. However, despite a pCO2 effect on various components of the plankton community, and a strong association between CH3I and biological parameters, no effect of pCO2 was seen in CH3I. Diiodomethane (CH2I2 displayed a number of strong relationships with biological parameters. Furthermore, the concentrations, the rate of net production and the sea-to-air flux of CH2I2 showed a significant positive response to pCO2. There was no clear effect of pCO2 on bromocarbon concentrations or dynamics. However, periods of significant net loss of bromoform (CHBr3 were found to be concentration-dependent, and closely correlated with total bacteria, suggesting a degree of biological consumption of this halocarbon in Arctic waters. Although the effects of OA on halocarbon concentrations were marginal, this study provides invaluable information on the production and cycling of halocarbons in a region of the world

  4. Multimodel simulations of Arctic Ocean sea surface height variability in the period 1970-2009

    DEFF Research Database (Denmark)

    Koldunov, Nikolay V.; Serra, Nuno; Koehl, Armin

    2014-01-01

    The performance of several numerical ocean models is assessed with respect to their simulation of sea surface height (SSH) in the Arctic Ocean, and the main patterns of SSH variability and their causes over the past 40 years (1970-2009) are analyzed. In comparison to observations, all tested models...... broadly reproduce the mean SSH in the Arctic and reveal a good correlation with both tide gauge data and SSH anomalies derived from satellite observations. Although the models do not represent the positive Arctic SSH trend observed over the last two decades, their interannual-to-decadal SSH variability...... is in reasonable agreement with available measurements. Focusing on results from one of the models for a detailed analysis, it is shown that the decadal-scale SSH variability over shelf areas and deep parts of the Arctic Ocean have pronounced differences that are determined mostly by salinity variations. A further...

  5. Unique archaeal assemblages in the Arctic Ocean unveiled by massively parallel tag sequencing.

    Science.gov (United States)

    Galand, Pierre E; Casamayor, Emilio O; Kirchman, David L; Potvin, Marianne; Lovejoy, Connie

    2009-07-01

    The Arctic Ocean plays a critical role in controlling nutrient budgets between the Pacific and Atlantic Ocean. Archaea are key players in the nitrogen cycle and in cycling nutrients, but their community composition has been little studied in the Arctic Ocean. Here, we characterize archaeal assemblages from surface and deep Arctic water masses using massively parallel tag sequencing of the V6 region of the 16S rRNA gene. This approach gave a very high coverage of the natural communities, allowing a precise description of archaeal assemblages. This first taxonomic description of archaeal communities by tag sequencing reported so far shows that it is possible to assign an identity below phylum level to most (95%) of the archaeal V6 tags, and shows that tag sequencing is a powerful tool for resolving the diversity and distribution of specific microbes in the environment. Marine group I Crenarchaeota was overall the most abundant group in the Arctic Ocean and comprised between 27% and 63% of all tags. Group III Euryarchaeota were more abundant in deep-water masses and represented the largest archaeal group in the deep Atlantic layer of the central Arctic Ocean. Coastal surface waters, in turn, harbored more group II Euryarchaeota. Moreover, group II sequences that dominated surface waters were different from the group II sequences detected in deep waters, suggesting functional differences in closely related groups. Our results unveiled for the first time an archaeal community dominated by group III Euryarchaeota and show biogeographical traits for marine Arctic Archaea.

  6. Key Arctic pelagic mollusc (Limacina helicina) threatened by ocean acidification

    Science.gov (United States)

    Comeau, S.; Gorsky, G.; Jeffree, R.; Teyssié, J.-L.; Gattuso, J.-P.

    2009-02-01

    Thecosome pteropods (shelled pelagic molluscs) can play an important role in the food web of various ecosystems and play a key role in the cycling of carbon and carbonate. Since they harbor an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The impact of changes in the carbonate chemistry was investigated on Limacina helicina, a key species of Arctic ecosystems. Pteropods were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.

  7. Occurrence of perfluoroalkyl compounds in surface waters from the North Pacific to the Arctic Ocean.

    Science.gov (United States)

    Cai, Minghong; Zhao, Zhen; Yin, Zhigao; Ahrens, Lutz; Huang, Peng; Cai, Minggang; Yang, Haizhen; He, Jianfeng; Sturm, Renate; Ebinghaus, Ralf; Xie, Zhiyong

    2012-01-17

    Perfluoroalkyl compounds (PFCs) were determined in 22 surface water samples (39-76°N) and three sea ice core and snow samples (77-87°N) collected from North Pacific to the Arctic Ocean during the fourth Chinese Arctic Expedition in 2010. Geographically, the average concentration of ∑PFC in surface water samples were 560 ± 170 pg L(-1) for the Northwest Pacific Ocean, 500 ± 170 pg L(-1) for the Arctic Ocean, and 340 ± 130 pg L(-1) for the Bering Sea, respectively. The perfluoroalkyl carboxylates (PFCAs) were the dominant PFC class in the water samples, however, the spatial pattern of PFCs varied. The C(5), C(7) and C(8) PFCAs (i.e., perfluoropentanoate (PFPA), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA)) were the dominant PFCs in the Northwest Pacific Ocean while in the Bering Sea the PFPA dominated. The changing in the pattern and concentrations in Pacific Ocean indicate that the PFCs in surface water were influenced by sources from the East-Asian (such as Japan and China) and North American coast, and dilution effect during their transport to the Arctic. The presence of PFCs in the snow and ice core samples indicates an atmospheric deposition of PFCs in the Arctic. The elevated PFC concentration in the Arctic Ocean shows that the ice melting had an impact on the PFC levels and distribution. In addition, the C(4) and C(5) PFCAs (i.e., perfluorobutanoate (PFBA), PFPA) became the dominant PFCs in the Arctic Ocean indicating that PFBA is a marker for sea ice melting as the source of exposure.

  8. Recent oceanic changes in the Arctic in the context of long-term observations.

    Science.gov (United States)

    Polyakov, Igor V; Bhatt, Uma S; Walsh, John E; Abrahamsen, E Povl; Pnyushkov, Andrey V; Wassmann, Paul F

    2013-12-01

    This synthesis study assesses recent changes of Arctic Ocean physical parameters using a unique collection of observations from the 2000s and places them in the context of long-term climate trends and variability. Our analysis demonstrates that the 2000s were an exceptional decade with extraordinary upper Arctic Ocean freshening and intermediate Atlantic water warming. We note that the Arctic Ocean is characterized by large amplitude multi-decadal variability in addition to a long-term trend, making the link of observed changes to climate drivers problematic. However, the exceptional magnitude of recent high-latitude changes (not only oceanic, but also ice and atmospheric) strongly suggests that these recent changes signify a potentially irreversible shift of the Arctic Ocean to a new climate state. These changes have important implications for the Arctic Ocean's marine ecosystem, especially those components that are dependent on sea ice or that have temperature-dependent sensitivities or thresholds. Addressing these and other questions requires a carefully orchestrated combination of sustained multidisciplinary observations and advanced modeling.

  9. Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

    Directory of Open Access Journals (Sweden)

    A. Kriegsmann

    2013-03-01

    Full Text Available This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration on the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important reasons for the recent ice extent minima in 2007 and 2012.

  10. Ice, Ocean and Atmosphere Interactions in the Arctic Marginal Ice Zone

    Science.gov (United States)

    2015-09-30

    release; distribution is unlimited. DRI TECHNICAL PROGRAM: Emerging Dynamics Of The Marginal Ice Zone Ice, Ocean and Atmosphere Interactions in the... Arctic Marginal Ice Zone Year 4 Annual Report Jeremy Wilkinson British Antarctic Survey phone: 44 (0)1223 221489 fax: 44 (0) 1223...global) scientific team in order to better understand the ocean , sea ice and atmosphere interaction within the marginal ice zone

  11. Observation-Based Assessment of PBDE Loads in Arctic Ocean Waters.

    Science.gov (United States)

    Salvadó, Joan A; Sobek, Anna; Carrizo, Daniel; Gustafsson, Örjan

    2016-03-01

    Little is known about the distribution of polybrominated diphenyl ethers (PBDE) -also known as flame retardants- in major ocean compartments, with no reports yet for the large deep-water masses of the Arctic Ocean. Here, PBDE concentrations, congener patterns and inventories are presented for the different water masses of the pan-Arctic shelf seas and the interior basin. Seawater samples were collected onboard three cross-basin oceanographic campaigns in 2001, 2005, and 2008 following strict trace-clean protocols. ∑14PBDE concentrations in the Polar Mixed Layer (PML; a surface water mass) range from 0.3 to 11.2 pg·L(-1), with higher concentrations in the pan-Arctic shelf seas and lower levels in the interior basin. BDE-209 is the dominant congener in most of the pan-Arctic areas except for the ones close to North America, where penta-BDE and tetra-BDE congeners predominate. In deep-water masses, ∑14PBDE concentrations are up to 1 order of magnitude higher than in the PML. Whereas BDE-209 decreases with depth, the less-brominated congeners, particularly BDE-47 and BDE-99, increase down through the water column. Likewise, concentrations of BDE-71 -a congener not present in any PBDE commercial mixture- increase with depth, which potentially is the result of debromination of BDE-209. The inventories in the three water masses of the Central Arctic Basin (PML, intermediate Atlantic Water Layer, and the Arctic Deep Water Layer) are 158 ± 77 kg, 6320 ± 235 kg and 30800 ± 3100 kg, respectively. The total load of PBDEs in the entire Arctic Ocean shows that only a minor fraction of PBDEs emissions are transported to the Arctic Ocean. These findings represent the first PBDE data in the deep-water compartments of an ocean.

  12. T, S, and U: Arctic Ocean Change in Response to Sea Ice Loss and Other Forcings

    Science.gov (United States)

    Steele, M.

    2015-12-01

    The Arctic Ocean is changing rapidly, partly in response to sea ice loss and partly from other forcings. Here we consider the three main parameters of physical oceanography: temperature, salinity, and momentum. With regard to temperature, the ocean is experiencing enhanced seasonal surface warming each summer as the ice pack retreats and thins. Some of this summer heat can persist through the winter below the surface mixed layer, although enhanced mixing and other processes can act against this survival. Deeper subsurface layers advected into the Arctic from the North Pacific and North Atlantic Oceans are also warming as these areas respond to warming trends and decadal climate variability. Arctic Ocean warming has implications for the mass balance of the sea ice pack, as well as both marine and coastal terrestrial ecosystems. With regard to salinity, the ocean has just begun to show an overall freshening signal, although with high spatial and temporal variance. This freshening is partly a result of sea ice melt, but also a response to global hydrologic and oceanographic changes. Arctic Ocean freshening enhances the surface stratification, which suppresses upward fluxes of heat and nutrients from below. It also reduces the transfer of momentum (i.e., the stress) from winds to the deep ocean. With regard to momentum, sea ice reduction has created a "looser" ice pack that allows more wind energy to enter the ocean. This effect opposes that of enhanced freshening/stratification when one considers mixing in the upper ocean; the sign and amplitude of the net result is a hot topic in the field. It should also be noted that surface stress in the summer season might actually be declining, as the rough ice pack transitions to a generally smoother sparse pack or open water. In summary, the Arctic Ocean is on the cusp of great change, largely (but not exclusively) forced by changes in the sea ice pack.

  13. Distribution of 226Ra in the Arctic Ocean and the Bering Sea and its hydrologic implications

    Institute of Scientific and Technical Information of China (English)

    邢娜; 陈敏; 黄奕普; 蔡平河; 邱雨生

    2003-01-01

    Radium-226 (226Ra) activities were measured in the surface water samples collected from the Arctic Ocean and the Bering Sea during the First Chinese National Arctic Research Expedition. The results showed that 226Ra concentrations in the surface water ranged from 0.28 to 1.56 Bq/m3 with an average of 0.76 Bq/m3 in the Arctic Ocean, and from 0.25 to 1.26 Bq/m3 with an average of 0.71 Bq/m3 in the Bering Sea. The values were obviously lower than those from open oceans in middle and low latitudes, indicating that the study area may be partly influenced by sea ice meltwater. In the Bering Sea, 226Ra in the surface water decreased northward, probably as a result of the exchange between the 226Ra-deficientsea ice meltwater and the 226Ra-rich Pacific water. In the Arctic Ocean, 226Ra in the surface water increased northward and eastward. This spatial distributionof 226Ra reflected the variation of the 226Ra-enriched river component in the water mass of the Arctic Ocean. The vertical profiles of 226Ra in the Canadian Basin showed a concentration maximum at 200 m, which could be attributed to the inputs of the Pacific water or/and the bottom shelf water with high 226Ra concentration. This conclusion was consistent with the results from 2H, 18O tracers.

  14. Sea level variability in the Arctic Ocean observed by satellite altimetry

    Directory of Open Access Journals (Sweden)

    P. Prandi

    2012-07-01

    Full Text Available We investigate sea level variability in the Arctic Ocean from observations. Variability estimates are derived both at the basin scale and on smaller local spatial scales. The periods of the signals studied vary from high frequency (intra-annual to long term trends. We also investigate the mechanisms responsible for the observed variability. Different data types are used, the main one being a recent reprocessing of satellite altimetry data in the Arctic Ocean.

    Satellite altimetry data is compared to tide gauges measurements, steric sea level derived from temperature and salinity fields and GRACE ocean mass estimates. We establish a consistent regional sea level budget over the GRACE availability era (2003–2009 showing that the sea level drop observed by altimetry over this period is driven by ocean mass loss rather than steric effects. The comparison of altimetry and tide gauges time series show that the two techniques are in good agreement regarding sea level trends. Coastal areas of high variability in the altimetry record are also consistent with tide gauges records. An EOF analysis of September mean altimetry fields allows identifying two regions of wind driven variability in the Arctic Ocean: the Beaufort Gyre region and the coastal European and Russian Arctic. Such patterns are related to atmospheric regimes through the Arctic Oscillation and Dipole Anomaly.

  15. Neogloboquadrina pachyderma in the modern Arctic Ocean: a potential for its morophological variation for paleoceanographic reconstruction

    Science.gov (United States)

    Asahi, Hirofumi; Nam, Seung-Il; Son, Yeong-Ju; Mackensen, Andreas; Stein, Ruediger

    2016-04-01

    In the Arctic Ocean, nearly entire planktic foraminifers are comprised of cold-water species Neogloboquadrina pachyderma sin. Its extreme dominance prevents extracting past environmental condition in the Arctic Ocean from planktic foraminiferal assemblages. Though potential usability of N. pachyderma's morphological variation for paleoceanographic reconstruction has been presented by recent studies, its application is still limited within a certain region (e.g., N. Atlantic side of the Arctic Ocean), leading requirement for further testing on the Pacific side of the Arctic Ocean. In this presentation, we will present the modern distribution of morphological variations of N. pachyderma, using 82 surface sediment samples collected in the western Arctic Ocean. Within investigated surface sediment samples, we have encountered total of seven morphological variations of N. pachyderma, compromising their description by previous study (Eynaund et al., 2010). Clear geographic distribution of "Large-sized (>250 μm)" N. pachyderma along the offshore of Northern Alaskan margin suggests its preferences in the relatively warm and low-salinity condition. Using the distribution pattern of morphological variations of N. pachyderma, we have succeeded to establish transfer functions for salinity and temperature. Application of those functions at down-core foraminiferal assemblages at the Northwind Ridge (ARA01B-MUC05: 75 °N, 160°W) showed general warming of ~0.5 °C and freshening of ~1.0 ‰ during Holocene.

  16. Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

    DEFF Research Database (Denmark)

    Forsberg, René; Skourup, Henriette

    2005-01-01

    ICESat laser measurements provide a high-resolution mapping of the sea-ice surface of the Arctic Ocean, which can be inverted to determine gravity anomalies and sea-ice freeboard heights by a "lowest-level'' filtering scheme. In this paper we use updated terrestrial gravity data from the Arctic...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....... Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...

  17. Contribution of oceanic gas hydrate dissociation to the formation of Arctic Ocean methane plumes

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, M.; Moridis, G.; Elliott, S.; Maltrud, M.

    2011-06-01

    Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of carbon into the atmosphere. Because methane is a powerful greenhouse gas, such a release could have dramatic climatic consequences. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope (150 m - 400 m) west of Svalbard suggests that this process may already have begun, but the source of the methane has not yet been determined. This study performs 2-D simulations of hydrate dissociation in conditions representative of the Arctic Ocean margin to assess whether such hydrates could contribute to the observed gas release. The results show that shallow, low-saturation hydrate deposits, if subjected to recently observed or future predicted temperature changes at the seafloor, can release quantities of methane at the magnitudes similar to what has been observed, and that the releases will be localized near the landward limit of the GHSZ. Both gradual and rapid warming is simulated, along with a parametric sensitivity analysis, and localized gas release is observed for most of the cases. These results resemble the recently published observations and strongly suggest that hydrate dissociation and methane release as a result of climate change may be a real phenomenon, that it could occur on decadal timescales, and that it already may be occurring.

  18. Provenance analysis of central Arctic Ocean sediments: Implications for circum-Arctic ice sheet dynamics and ocean circulation during Late Pleistocene

    Science.gov (United States)

    Kaparulina, Ekaterina; Strand, Kari; Lunkka, Juha Pekka

    2016-09-01

    Mineralogical and geochemical data generated from the well referred shallow core 96/12-1pc on the Lomonosov Ridge, central Arctic Ocean was used to evaluate ice transport from the circum-Arctic sources and variability in sediment drainage and provenance changes. In this study heavy minerals in central Arctic sediments were used to determine those most prominent provenance areas and their changes related to the Late Pleistocene history of glaciations in the Arctic. Provenance changes were then used to infer variations in the paleoceanographic environment of the central Arctic Ocean, such as variations in the distribution of sea ice, icebergs controlled by the Arctic Ocean circulation. Four critical end-members including Victoria and Banks Islands, the Putorana Plateau, the Anabar Shield, and the Verkhoyansk Fold Belt were identified from the Amerasian and Eurasian source areas, and their proportional contributions were estimated in relation to Late Pleistocene ice sheet dynamics and ocean circulation. The results show changes in transport pathways and source areas within two examined transitions MIS6-5 and MIS4-3. The main source for material during MIS6-5 transition was Amerasian margin due to the high dolomite content in the studied section of sediments inferring strong Beaufort Gyre (BG) and Transpolar Drift (TPD) transport for this material. IRD material during late the MIS6 to 5 deglacial event was from terrigenous input through from the MacKenzie route Banks/Victoria Islands then transported as far as the Lomonosov Ridge area. The transition, MIS4-3 in comparison with MIS6-5, shows a clear shift in source areas, reflected in a different mineralogical composition of sediments, supplied from the Eurasian margin, such as the Anabar Shield, the Putorana Plateau and the Verkhoyansk Fold Belt during active decay of the Barents-Kara Ice Sheet presumable associated with an ice-dammed lake outburst then triggered by a strong TPD over the central Arctic. These two

  19. UAV Deployed Sensor System for Arctic Ocean Remote Sensing

    Science.gov (United States)

    Palo, S. E.; Lawrence, D.; Weibel, D.; LoDolce, G.; Krist, S.; Crocker, I.; Maslanik, J. A.

    2012-12-01

    The Marginal Ice Zone Observations and Processes Experiment (MIZOPEX), is an Arctic field project scheduled for summer 2013. The goals of the project are to understand how warming of the marginal ice zone affects sea ice melt and if this warming has been over or underestimated by satellite measurements. To achieve these goals calibrated physical measurements, both remote and in-situ, of the marginal ice zone over scales of square kilometers with a resolution of square meters is required. This will be accomplished with a suite of unmanned aerial vehicles (UAVs) equipped with both remote sensing and in-situ instruments, air deployed microbuoys, and ship deployed buoys. In this talk we will present details about the air-deployed micro-buoy (ADMB) and self-deployed surface-sonde (SDSS) components of the MIZOPEX project, developed at the University of Colorado. These systems were designed to explore the potential of low-cost, on-demand access to high-latitude areas of important scientific interest. Both the ADMB and SDSS share a common measurement suite with the capability to measure water temperature at three distinct depths and provide position information via GPS. The ADMBs are dropped from the InSitu ScanEagle UAV and expected to operate and log ocean temperatures for 14 days. The SDSS are micro UAVs that are designed to fly one-way to a region of interest and land at specified coordinates, thereafter becoming a surface sensor similar to the ADMB. A ScanEagle will periodically return to the deployment zone to gather ADMB/SDSS data via low power radio links. Design decisions based upon operational constraints and the current status of the ADMB and SDSS will be presented.

  20. A 2006-2007 Update on Oceanographic Conditions in the Central Arctic Ocean

    Science.gov (United States)

    Morison, J. H.; Steele, M.; Wahr, J.; Alkire, M.; Peralta-Ferriz, C.; Kwok, R.; Kikuchi, T.

    2007-12-01

    Trends in central Arctic Ocean conditions are updated with recently gathered data. In the late 1980s and through the 1990s we saw major shifts in the Arctic Ocean. The influence of Atlantic Water in the Arctic Ocean became more widespread and intense and the pattern of water circulation and ice drift shifted, resulting in a more cyclonic circulation. These changes became manifest in the central Arctic near the North Pole as increases in upper ocean salinity and Atlantic Water temperature. They occurred in concert with a decrease in surface atmospheric pressure. With the aim of helping to track such changes, the North Pole Environmental Observatory (NPEO) has been maintained since 2000. Along with an automated drifting station and a deep ocean mooring near the Pole; NPEO conducts airborne hydrographic surveys that track changes along key sections radiating from the Pole. In a related project, several of us have undertaken in situ ocean bottom pressure measurements and the analysis of Gravity Recovery and Climate Experiment (GRACE) data to track changes in the distribution of ocean mass. Hydrographic measurements made by the NPEO show that between 2000 and 2005, oceanographic condition relaxed toward the pre-1990 state. Morison et al [2006] describe these changes and relate them to a decline in the Arctic Oscillation (AO) index. On the basis of in situ and GRACE bottom pressure trends, Morison et al. [2007] argue that shift back to pre-1990s circulation extended over the whole Arctic Ocean. The Spring 2007 NPEO hydrographic surveys and the 2006-2007 bottom pressure data suggest the trend towards pre-1990s conditions has now, once again, reversed. The new observations show greater salinities and bottom pressure near the Pole, indicative of increased Atlantic water presence. Temperatures have increased in the Atlantic Water core along the Eurasian flank of the Lomonosov Ridge. We will explore these most recent changes and their relation to changes in the ice cover and

  1. A Holocene cryptotephra record from the Chukchi margin: the first tephrostratigraphic study in the Arctic Ocean

    OpenAIRE

    Ponomareva, Vera; Polyak, Leonid; Portnyagin, Maxim; Abbott, Peter; Davies, Siwan

    2014-01-01

    Developing geochronology for sediments in the Arctic Ocean and its continental margins is an important but challenging task complicated by multiple problems. In particular, the Chukchi/Beaufort margin, a critical area for reconstructing paleoceanographic conditions in the Pacific sector of the Arctic, features widespread dissolution of calcareous material, which limits posibilities for radiocarbon chronology. In order to evaluate the untapped potential of tephrochronology for constraining the...

  2. Species richness and distribution of chondrichthyan fishes in the Arctic Ocean and adjacent seas

    DEFF Research Database (Denmark)

    Lynghammar, A.; Christiansen, J. S.; Mecklenburg, C. W.

    2013-01-01

    The sea ice cover decreases and human activity increases in Arctic waters. Fisheries and bycatch issues, shipping and petroleum exploitation (pollution issues) make it imperative to establish biological baselines for the marine fishes inhabiting the Arctic Ocean and adjacent seas (AOAS). Species...... richness, zoogeographic affiliations and Red List statuses among chondrichthyan fishes (Chondrichthyes) were examined across 16 AOAS regions as a first step towards credible conservation actions. Published literature and museum vouchers were consulted for presence/absence data. Although many regions...

  3. Hydrographic changes in the Lincoln Sea in the Arctic Ocean with focus on an upper ocean freshwater anomaly between 2007 and 2010

    NARCIS (Netherlands)

    de Steur, L.; Steele, M.; Hansen, E.; Morison, J.; Polyakov, I.; Olsen, S.M.; Melling, H.; McLaughlin, F.A.; Kwok, R.; Smethie Jr., W.M.; Schlosser, P.

    2013-01-01

    Hydrographic data from the Arctic Ocean show that freshwater content in the Lincoln Sea, north of Greenland, increased significantly from 2007 to 2010, slightly lagging changes in the eastern and central Arctic. The anomaly was primarily caused by a decrease in the upper ocean salinity. In 2011 uppe

  4. Biological response to climate change in the Arctic Ocean: The view from the past

    Science.gov (United States)

    Cronin, Thomas M.; Cronin, Matthew A.

    2017-01-01

    The Arctic Ocean is undergoing rapid climatic changes including higher ocean temperatures, reduced sea ice, glacier and Greenland Ice Sheet melting, greater marine productivity, and altered carbon cycling. Until recently, the relationship between climate and Arctic biological systems was poorly known, but this has changed substantially as advances in paleoclimatology, micropaleontology, vertebrate paleontology, and molecular genetics show that Arctic ecosystem history reflects global and regional climatic changes over all timescales and climate states (103–107 years). Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals. Climate-driven biological impacts included large changes in species diversity, primary productivity, species’ geographic range shifts into and out of the Arctic, community restructuring, and possible hybridization, but evidence is not sufficient to determine whether or when major episodes of extinction occurred.

  5. New aero-gravity results from the Arctic: Linking the latest Cretaceous-early Cenozoic plate kinematics of the North Atlantic and Arctic Ocean

    DEFF Research Database (Denmark)

    Døssing, Arne; Hopper, J.R.; Olesen, Arne Vestergaard

    2013-01-01

    The tectonic history of the Arctic Ocean remains poorly resolved and highly controversial. Details regarding break up of the Lomonosov Ridge from the Barents-Kara shelf margins and the establishment of seafloor spreading in the Cenozoic Eurasia Basin are unresolved. Significantly, the plate...... tectonic evolution of the Mesozoic Amerasia Basin is essentially unknown. The Arctic Ocean north of Greenland is at a critical juncture that formed at the locus of a Mesozoic three-plate setting between the Lomonosov Ridge, Greenland, and North America. In addition, the area is close to the European plate...... plateau against an important fault zone north of Greenland. Our results provide new constraints for Cretaceous-Cenozoic plate reconstructions of the Arctic. Key Points Presentation of the largest aero-gravity survey acquired over the Arctic Ocean Plate tectonic link between Atlantic and Arctic spreading...

  6. Atmospheric Black Carbon along a Cruise Path through the Arctic Ocean during the Fifth Chinese Arctic Research Expedition

    Directory of Open Access Journals (Sweden)

    Jie Xing

    2014-05-01

    Full Text Available From July to September 2012, during the fifth Chinese National Arctic Research Expedition (CHINARE, the concentrations of black carbon (BC aerosols inside the marine boundary layer were measured by an in situ aethalometer. BC concentrations ranged from 0.20 ng∙m−3 to 1063.20 ng∙m−3, with an average of 75.74 ng∙m−3. The BC concentrations were significantly higher over the mid-latitude and coastal areas than those over the remote ocean and high latitude areas. The highest average concentration was found over offshore China (643.44 ng∙m−3 during the cruise, while the lowest average was found over the Arctic Ocean (5.96 ng∙m−3. BC aerosol was found mainly affected by the terrestrial input and displayed seasonal and spatial variations. Compared with the results from the third and fourth CHINARE of summer 2008, and summer 2010, the inter-annual variation of BC over the Arctic Ocean was negligible.

  7. Impact of CryoSat-2 for marine gravity field - globally and in the Arctic Ocean

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Stenseng, Lars; Knudsen, Per

    days repeat offered by CryoSat-2 provides denser coverage than older geodetic mission data set like ERS-1. Thirdly, the 92 degree inclination of CryoSat-2 is designed to map more of the Arctic Ocean than previous altimetric satellites. Finally, CryoSat-2 is able to operate in two new modes (SAR and SAR...... GDR data, NOAA LRM data, but also Level1b (LRM, SAR and SAR-in waveforms) data have been analyzed. A suite of eight different empirical retrackers have been developed and investigated for their ability to predict marine gravity in the Arctic Ocean. The impact of the various improvement offered by Cryo......Sat-2 in comparison with conventional satellite altimetry have been studied and quantified both globally but particularly for the Arctic Ocean using a large number of marine and airborne surveys providing “ground truth” marine gravity....

  8. Wind-driven mixing at intermediate depths in an ice-free Arctic Ocean

    Science.gov (United States)

    Lincoln, Ben J.; Rippeth, Tom P.; Lenn, Yueng-Djern; Timmermans, Mary Louise; Williams, William J.; Bacon, Sheldon

    2016-09-01

    Recent seasonal Arctic Ocean sea ice retreat is a major indicator of polar climate change. The Arctic Ocean is generally quiescent with the interior basins characterized by low levels of turbulent mixing at intermediate depths. In contrast, under conditions of reduced sea ice cover, there is evidence of energetic internal waves that have been attributed to increased momentum transfer from the atmosphere to the ocean. New measurements made in the Canada Basin during the unusually ice-free and stormy summer of 2012 show previously observed enhancement of internal wave energy associated with ice-free conditions. However, there is no enhancement of mixing at intermediate depths away from significant topography. This implies that contrary to expectations of increased wind-induced mixing under declining Arctic sea ice cover, the stratification in the central Canada Basin continues to suppress turbulent mixing at intermediate depths and to effectively isolate the large Atlantic and Pacific heat reservoirs from the sea surface.

  9. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    OpenAIRE

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Rapp, Josephine Z.; Buttigieg, Pier Luigi; Krumpen, Thomas; Jonathan P Zehr; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which ...

  10. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    KAUST Repository

    Holding, J. M.

    2015-08-31

    The Arctic Ocean is warming at two to three times the global rate1 and is perceived to be a bellwether for ocean acidification2, 3. Increased CO2 concentrations are expected to have a fertilization effect on marine autotrophs4, and higher temperatures should lead to increased rates of planktonic primary production5. Yet, simultaneous assessment of warming and increased CO2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO2-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range of 145–2,099 μatm; however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO2-enhanced primary production has significant implications for metabolic balance in a warmer, CO2-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.

  11. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    Science.gov (United States)

    Holding, J. M.; Duarte, C. M.; Sanz-Martín, M.; Mesa, E.; Arrieta, J. M.; Chierici, M.; Hendriks, I. E.; García-Corral, L. S.; Regaudie-de-Gioux, A.; Delgado, A.; Reigstad, M.; Wassmann, P.; Agustí, S.

    2015-12-01

    The Arctic Ocean is warming at two to three times the global rate and is perceived to be a bellwether for ocean acidification. Increased CO2 concentrations are expected to have a fertilization effect on marine autotrophs, and higher temperatures should lead to increased rates of planktonic primary production. Yet, simultaneous assessment of warming and increased CO2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO2-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range of 145-2,099 μatm however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO2-enhanced primary production has significant implications for metabolic balance in a warmer, CO2-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.

  12. Petroleum prospectivity of the Canada Basin, Arctic Ocean

    Science.gov (United States)

    Grantz, A.; Hart, P.E.

    2011-01-01

    Reconnaissance seismic reflection data indicate that Canada Basin is a remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed on the northern part of the Amerasia Basin between about 127 and 89-75 Ma. Canada Basin is filled with Early Jurassic to Holocene detritus from the Mackenzie River system, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. Except for the absence of a salt- and shale-bearing mobile substrate Canada Basin is analogous to the Mississippi Delta and the western Gulf of Mexico. Canada Basin contains about 7 to >14 km of sediment beneath the Mackenzie Prodelta on the southeast, 6 to 7 km of sediment beneath the abyssal plain on the west, and roughly 5 or 6 million cubic km of sediment. About three fourths of the basin fill generates low amplitude seismic reflections, interpreted to represent hemiplegic deposits, and a fourth of the fill generates interbedded lenses to extensive layers of moderate to high amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits. Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin may contain intervals of hydrocarbon source rocks and the apparent age of the basin suggests that it contains three of the six stratigraphic intervals that together provided >90?? of the World's discovered reserves of oil and gas.. Worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas window. At least five types of structural or stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin. These consist of 1) a belt of late Eocene to Miocene shale-cored detachment folds containing with at least two anticlines that are capped by beds with bright spots, 2) numerous moderate to high amplitude reflection packets

  13. The contribution of Alaskan, Siberian, and Canadian coastal polynas to the cold halocline layer of the Arctic Ocean

    Science.gov (United States)

    Cavalieri, Donald J.; Martin, Seelye

    1994-01-01

    Numerous Arctic Ocean circulation and geochemical studies suggest that ice growth in polynyas over the Alaskan, Siberian, and Canadian continental shelves is a source of cold, saline water which contributes to the maintenance of the Arctic Ocean halocline. The purpose of this study is to estimate for the 1978-1987 winters the contributions of Arctic coastal polynyas to the cold halocline layer of the Arctic Ocean. The study uses a combination of satellite, oceanographic, and weather data to calculate the brine fluxes from the polynyas; then an oceanic box model is used to calculate their contributions to the cold halocline layer of the Arctic Ocean. This study complements and corrects a previous study of dense water production by coastal polynyas in the Barents, Kara, and Laptev Seas.

  14. Atmospheric moisture transport: the bridge between ocean evaporation and Arctic ice melting

    Science.gov (United States)

    Gimeno, L.; Vázquez, M.; Nieto, R.; Trigo, R. M.

    2015-09-01

    Changes in the atmospheric moisture transport have been proposed as a vehicle for interpreting some of the most significant changes in the Arctic region. The increasing moisture over the Arctic during the last decades is not strongly associated with the evaporation that takes place within the Arctic area itself, despite the fact that the sea ice cover is decreasing. Such an increment is consistent and is more dependent on the transport of moisture from the extratropical regions to the Arctic that has increased in recent decades and is expected to increase within a warming climate. This increase could be due either to changes in circulation patterns which have altered the moisture sources, or to changes in the intensity of the moisture sources because of enhanced evaporation, or a combination of these two mechanisms. In this short communication we focus on the more objective assessment of the strong link between ocean evaporation trends and Arctic Sea ice melting. We will critically analyse several recent results suggesting links between moisture transport and the extent of sea ice in the Arctic, this being one of the most distinct indicators of continuous climate change both in the Arctic and on a global scale. To do this we will use a sophisticated Lagrangian approach to develop a more robust framework on some of these previous disconnecting results, using new information and insights. Results reached in this study stress the connection between two climate change indicators, namely an increase in evaporation over source regions (mainly the Mediterranean Sea, the North Atlantic Ocean and the North Pacific Ocean in the paths of the global western boundary currents and their extensions) and Arctic ice melting precursors.

  15. Pliocene and Pleistocene chronostratigraphy and paleoenvironment of the Central Arctic Ocean, using deep water agglutinated foraminifera

    OpenAIRE

    Evans, J. R.; Kaminski, M.A

    1998-01-01

    Deep-water agglutinated foraminifera (DWAF) were studied from Cores PS2177-5, PS2200-5, PS2212-3 and PS2185-6; from the R/V POLARSTERN ARK-VIII/3 Cruise in the central Arctic Ocean. The sediments were non-calcareous containing a sparse assemblage of eleven DWAF species. A chronostratigraphic framework is presented for Cores PS2200-5 and PS2185-6. Paleoenvironmental data suggests a bathyal environment (2000-4000m) affected by water masses in the Arctic Ocean. The taxonomy of all of the DWAF fo...

  16. Observing the Arctic Ocean under melting ice - the UNDER-ICE project

    Science.gov (United States)

    Sagen, Hanne; Ullgren, Jenny; Geyer, Florian; Bergh, Jon; Hamre, Torill; Sandven, Stein; Beszczynska-Möller, Agnieszka; Falck, Eva; Gammelsrød, Tor; Worcester, Peter

    2014-05-01

    The sea ice cover of the Arctic Ocean is gradually diminishing in area and thickness. The variability of the ice cover is determined by heat exchange with both the atmosphere and the ocean. A cold water layer with a strong salinity gradient insulates the sea ice from below, preventing direct contact with the underlying warm Atlantic water. Changes in water column stratification might therefore lead to faster erosion of the ice. As the ice recedes, larger areas of surface water are open to wind mixing; the effect this might have on the water column structure is not yet clear. The heat content in the Arctic strongly depends on heat transport from other oceans. The Fram Strait is a crucial pathway for the exchange between the Arctic and the Atlantic Ocean. Two processes of importance for the Arctic heat and freshwater budget and the Atlantic meridional overturning circulation take place here: poleward heat transport by the West Spitzbergen Current and freshwater export by the East Greenland Current. A new project, Arctic Ocean under Melting Ice (UNDER-ICE), aims to improve our understanding of the ocean circulation, water mass distribution, fluxes, and mixing processes, sea ice processes, and net community primary production in ice-covered areas and the marginal ice zone in the Fram Strait and northward towards the Gakkel Ridge. The interdisciplinary project brings together ocean acoustics, physical oceanography, marine biology, and sea ice research. A new programme of observations, integrated with satellite data and state-of-the-art numerical models, will be started in order to improve the estimates of heat, mass, and freshwater transport between the North Atlantic and the Arctic Ocean. On this poster we present the UNDER-ICE project, funded by the Research Council of Norway and GDF Suez E&P Norge AS for the years 2014-2017, and place it in context of the legacy of earlier projects in the area, such as ACOBAR. A mooring array for acoustic tomography combined with

  17. New evidence for ice shelf flow across the Alaska and Beaufort margins, Arctic Ocean

    Science.gov (United States)

    Engels, Jennifer L.

    The Arctic Ocean may act as a lynchpin for global climate change due to its unique physiography as a mediterranean sea located in polar latitudes. In our modern warming climate, debate over the bounds of natural versus anthropogenically-induced climate variability necessitates a comprehensive understanding of Arctic ice extent and configuration over the last interglacial cycle. Longstanding controversy exists as to the volume, timing, and flow trajectories of ice in the Arctic Ocean during glacial maxima when continental ice sheets mantled circum-arctic landmasses. As a result of the Science Ice Exercise surveys of the Arctic Ocean in 1999, new evidence for ice grounding at depths down to 980 m on the Lomonosov Ridge and 750 m on the Chukchi Borderland indicates the likelihood that large ice shelves flowed into the ocean from both the Barents/Kara Sea and the Canadian Arctic Archipelago or eastern Alaska. Sidescan imagery of ˜14100 km2 of seafloor along the Alaska and Beaufort margins in water depths from 250--2800 m maps a repetitive association of recognizable sub-glacially generated bedforms, ice carved-bathymerry, and ice-marginal turbidite gullies over a 640 km stretch of the margin between Point Barrow and the MacKenzie River delta. Glaciogenic bedforms occur across the surface of a flattened bathymetric bench or 'second shelf break' that is interpreted to have been formed by an ice shelf eroding the continental slope. The glacial geology of surrounding areas suggests that an ice shelf on the Alaska and Beaufort margins likely flowed from the mouths of overdeepened glacial troughs in the Canadian Arctic Archipelago westward and across the Chukchi Borderland due to an obstruction in the central Canadian basin. Evidence for an ice shelf along the Alaska and Beaufort margins supports an expanded interpretation of ice volume and extent during Pleistocene glacial periods. This has far-reaching implications for Arctic climate studies, ocean circulation, sediment

  18. Wrench faulting in the Canada Basin, Arctic Ocean

    Science.gov (United States)

    Hutchinson, D. R.; Jackson, H. R.; Shimeld, J.; Houseknecht, D. W.; Chian, D.; Li, Q.; Saltus, R. W.; Oakey, G. N.

    2015-12-01

    Synthesis of seismic velocity, potential field, and geologic data from within the Canada Basin of the Arctic Ocean and its surrounding margins suggests that a northeast-trending structural fabric has influenced the origin, evolution, and current tectonics of the basin. This fabric is defined by a diverse set of observations, including (1) a magnetic lineament extending from offshore Prince Patrick Island to the bend in the Canada Basin Gravity Low that separates higher magnetic amplitudes to the northwest from a region of more subdued anomalies to the southeast; (2) the orientation of the 600-km long Northwind Escarpment along the edge of the Canada Basin; (3) a large, linear, positive magnetic anomaly that parallels Northwind Escarpment; (4) negative flower structures along the base of the Northwind Escarpment identified in seismic reflection profiles; (5) the edges of a linear, 150-km-long by 20-km-wide by 2000-m deep, basin in the Chukchi Plateau; (6) the sub-parallel ridges of Sever Spur along the Canadian margin north of Prince Patrick Island; (7) an oblong gravity low interpreted to indicate thick sediments beneath an inferred rift basin at 78oN in ~3600 m water depth; (8) the offshore extensions of the Canning sinistral and Richardson dextral fault zones; (9) the offshore extension of the D3 magnetic terrain of Saltus et al. (2011); and (10) the association of dredged rocks of the Chukchi Borderland with the Pearya terrane ~2000 km northeast of its present location (Brumley et al., 2015). Ongoing deformation of the Beaufort margin by impingement of the Brooks Range tectonic front is recorded by modern seismicity along the Canning and Richardson fault zones, which imply that deformation is accommodated by slip along the northeast-trending fabric. Together, these features are interpreted to indicate long-lived northeast-southwest oriented tectonic fabric in the development of the Canada Basin from initial rifting to modern deformation of the Beaufort margin

  19. "Recent" macrofossil remains from the Lomonosov Ridge, central Arctic Ocean

    Science.gov (United States)

    Le Duc, Cynthia; de Vernal, Anne; Archambault, Philippe; Brice, Camille; Roberge, Philippe

    2016-04-01

    years as suggested by the radiocarbon dating of the upper centimeter of the sediment in PS87/030-2 (7792 ± 59 14C years BP), PS87/055-1 (3897 ± 41 14C years BP), and PS87/099-4 (1421 ± 66 14C years BP). Reference Stein, R. (Ed.), 2015. The Expedition PS87 of the Research Vessel Polarstern to the Arctic Ocean in 2014, Reports on Polar and Marine Research 688, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 273 pp (http://epic.awi.de/37728/1/BzPM_0688_2015.pdf).

  20. The role of sustained observations and data co-management in Arctic Ocean governance

    Science.gov (United States)

    Eicken, H.; Lee, O. A.; Rupp, S. T.; Trainor, S.; Walsh, J. E.

    2015-12-01

    Rapid environmental change, a rise in maritime activities and resource development, and increasing engagement by non-Arctic nations are key to major shifts underway in Arctic social-environmental systems (SES). These shifts are triggering responses by policy makers, regulators and a range of other actors in the Arctic Ocean region. Arctic science can play an important role in informing such responses, in particular by (i) providing data from sustained observations to serve as indicators of change and major transitions and to inform regulatory and policy response; (ii) identifying linkages across subsystems of Arctic SES and across regions; (iii) providing predictions or scenarios of future states of Arctic SES; and (iv) informing adaptation action in response to rapid change. Policy responses to a changing Arctic are taking a multi-faceted approach by advancing international agreements through the Arctic Council (e.g., Search and Rescue Agreement), global forums (e.g., IMO Polar Code) or private sector instruments (e.g., ISO code for offshore structures). At the regional level, co-management of marine living resources involving local, indigenous stakeholders has proven effective. All of these approaches rely on scientific data and information for planning and decision-making. Examples from the Pacific Arctic sector illustrate how such relevant data is currently collected through a multitude of different government agencies, universities, and private entities. Its effective use in informing policy, planning and emergency response requires coordinated, sustained acquisition, common standards or best practices, and data sharing agreements - best achieved through data co-management approaches. For projections and scenarios of future states of Arctic SES, knowledge co-production that involves all relevant stakeholders and specifically addresses major sources of uncertainty is of particular relevance in an international context.

  1. Temporal and spatial characteristics of surface ozone depletion events from measurements over the Arctic Ocean

    Science.gov (United States)

    Halfacre, J. W.; Knepp, T. N.; Stephens, C. R.; Pratt, K. A.; Shepson, P.; Simpson, W. R.; Peterson, P. K.; Walsh, S. J.; Matrai, P. A.; Bottenheim, J. W.; Netcheva, S.; Perovich, D. K.; Richter, A.

    2012-12-01

    Arctic tropospheric ozone depletion events (ODEs) have been studied primarily from coastal sites since the mid 1980s with only a few studies occurring over the Arctic Ocean, the hypothesized site of initiation. Despite a multitude of studies, some basic characteristics of ODEs remain poorly defined, including their temporal, spatial, and meteorological characteristics. Several deployments of autonomous, ice-tethered buoys (O-Buoys) were used to elucidate such characteristics from both the Arctic Ocean and coastal sites. The apparent first order decays imply an ozone lifetime (median of 11 hours) that would correspond to a very large BrO concentration, relative to BrO observations obtained from the buoys. These results suggest that ODEs involve a large, unaccounted for source of bromine atoms, that there is a significant contribution from other mechanisms possibly not involving bromine, or that the majority of observed ODEs represent advection of previously-depleted air to the buoy site, even in the Arctic Ocean. Using backward air mass trajectories, the spatial scales for ODEs (defined by time periods with O3 ≤ 15 nmol/mol) were estimated to be ~1800 km (mode), suggesting that most of the lower troposphere above the Arctic Ocean is frequently, at least partially, depleted of ozone. Using the same method, areas estimated to be highly depleted of O3 (ice-tethered O-Buoys provide unique data to study the characteristics of ODEs; however, more remote and simultaneous surface observations over the Arctic Ocean are necessary to enable study of both the site(s) and mechanism(s) of ODE initiation.

  2. Arctic Ocean Sea Ice Thickness, Bathymetry, and Water Properties from Submarine Data

    Science.gov (United States)

    Windnagel, A. K.; Fetterer, F. M.

    2014-12-01

    The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration that began in 1993 among the operational Navy, research agencies, and the marine research community to use nuclear-powered submarines for scientific studies of the Arctic Ocean. Unlike surface ships and satellites, submarines have the unique ability to operate and take measurements regardless of sea ice cover, weather conditions, and time of year. This allows for a broad and comprehensive investigation of an entire ocean basin. The goal of the program is to acquire comprehensive data about Arctic sea ice thickness; biological, chemical, and hydrographic water properties; and bathymetry to improve our understanding of the Arctic Ocean basin and its role in the Earth's climate system. Ice draft is measured with upward looking sonars mounted on the submarine's hull. The work of collaborators on the SCICEX project compared recent ice draft from the submarines with draft from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) and with ice thickness estimates from ice age and have shown that SCICEX ice draft are consistent with these models. Bathymetry is measured with a bottom sounder. SCICEX bathymetry data from 1993 to 1999 are included in the International Bathymetric Chart of the Arctic Ocean (IBCAO). Collaborators have compared more recent bathymetry data collected through the SCICEX project with other IBCAO data, and they agree well. Water properties are measured with two different types of conductivity, temperature, and depth (CTD) sensors: one mounted on the submarine's hull and expendable versions that are deployed through the submarines torpedo tubes. Data from the two different CTD sensors validate one another. The breadth of instrumentation available from submarines along with their ability to be unencumbered by sea ice, weather, and season makes the data they have collected extremely valuable. The National Snow and Ice Data Center (NSIDC) manages this data

  3. On the Arctic Ocean ice thickness response to changes in the external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Stranne, Christian; Bjoerk, Goeran [University of Gothenburg, Department of Earth Sciences, Box 460, Goeteborg (Sweden)

    2012-12-15

    Submarine and satellite observations show that the Arctic Ocean ice cover has undergone a large thickness reduction and a decrease in the areal extent during the last decades. Here the response of the Arctic Ocean ice cover to changes in the poleward atmospheric energy transport, F{sub wall}, is investigated using coupled atmosphere-ice-ocean column models. Two models with highly different complexity are used in order to illustrate the importance of different internal processes and the results highlight the dramatic effects of the negative ice thickness - ice volume export feedback and the positive surface albedo feedback. The steady state ice thickness as a function of F{sub wall} is determined for various model setups and defines what we call ice thickness response curves. When a variable surface albedo and snow precipitation is included, a complex response curve appears with two distinct regimes: a perennial ice cover regime with a fairly linear response and a less responsive seasonal ice cover regime. The two regimes are separated by a steep transition associated with surface albedo feedback. The associated hysteresis is however small, indicating that the Arctic climate system does not have an irreversible tipping point behaviour related to the surface albedo feedback. The results are discussed in the context of the recent reduction of the Arctic sea ice cover. A new mechanism related to regional and temporal variations of the ice divergence within the Arctic Ocean is presented as an explanation for the observed regional variation of the ice thickness reduction. Our results further suggest that the recent reduction in areal ice extent and loss of multiyear ice is related to the albedo dependent transition between seasonal and perennial ice i.e. large areas of the Arctic Ocean that has previously been dominated by multiyear ice might have been pushed below a critical mean ice thickness, corresponding to the above mentioned transition, and into a state dominated

  4. Ice-tethered measurement platforms in the Arctic Ocean: a contribution by the FRAM infrastructure program

    Science.gov (United States)

    Hoppmann, Mario; Nicolaus, Marcel; Rabe, Benjamin; Wenzhöfer, Frank; Katlein, Christian; Scholz, Daniel

    2016-04-01

    The Arctic Ocean has been in the focus of many studies during recent years, investigating the state, the causes and the implications of the observed rapid transition towards a thinner and younger sea-ice cover. However, consistent observational datasets of sea ice, ocean and atmosphere are still sparse due to the limited accessibility and harsh environmental conditions. One important tool to fill this gap has become more and more feasible during recent years: autonomous, ice-tethered measurement platforms (buoys). These drifting instruments independently transmit their data via satellites, and enable observations over larger areas and over longer time periods than manned expeditions, even throughout the winter. One aim of the newly established FRAM (FRontiers in Arctic marine Monitoring) infrastructure program at the Alfred-Wegener-Institute is to realize and maintain an interdisciplinary network of buoys in the Arctic Ocean, contributing to an integrated, Arctic-wide observatory. The additional buoy infrastructure, ship-time, and developments provided by FRAM are critical elements in the ongoing international effort to fill the large data gaps in a rapidly changing Arctic Ocean. Our focus is the particularly underrepresented Eurasian Basin. Types of instruments range from snow depth beacons and ice mass balance buoys for monitoring ice growth and snow accumulation, over radiation and weather stations for energy budget estimates, to ice-tethered profiling systems for upper ocean monitoring. Further, development of new bio-optical and biogeochemical buoys is expected to enhance our understanding of bio-physical processes associated with Arctic sea ice. The first set of FRAM buoys was deployed in September 2015 from RV Polarstern. All datasets are publicly available on dedicated web portals. Near real time data are reported into international initiatives, such as the Global Telecommunication System (GTS) and the International Arctic Buoy Programme (IABP). The

  5. Studying the impact of changes in the Arctic outflow by using a coupled ice-ocean model

    Science.gov (United States)

    Pasha Karami, Mehdi; Myers, Paul G.; Tremblay, Bruno; de Vernal, Anne

    2016-04-01

    The export of cold and fresh water from the Arctic Ocean into the North Atlantic Ocean happens mainly through the Fram Strait and the Canadian Arctic Archipelago (CAA). The magnitude of the Arctic outflow and its distribution between the Fram Strait and CAA has been suggested to change in the future. Such changes might affect the Arctic sea ice, and possibly alter the location and the intensity of dense water formation and, therefore, the Atlantic meridional overturning circulation (AMOC). One factor controlling the Arctic outflow is the wind forcing. Another factor is the Atlantic inflow to the Arctic, which also depends on the wind forcing and is linked to the intermediate circulation within the Arctic. There is also synergy between all the Arctic gateways. Here we explore the changes in CAA and Fram outflows accompanying the Arctic dipole mode as a plausible climatic state in future, and their corresponding impacts on the Arctic and Atlantic Oceans. For this purpose, a regional configuration of the coupled ice-ocean model, NEMO (Nucleus for European Modelling of the Ocean model) version 3.4 is used for a set of sensitivity experiments. For the surface boundary condition, composites of atmospheric variables associated with the two phases of Arctic dipole mode were calculated from the COREII data. To better understand what controls the distribution of Arctic outflow between the Fram Strait and CAA and to exclude their synergism, we launch similar experiments with a closed CAA. This will allow us to better understand the impacts caused by the modulation of the wind forcing versus changes in the gateway flows. Our results will also have implications for the paleo-studies of the Arctic.

  6. Freshwater and its role in the Arctic Marine System: Sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans

    Science.gov (United States)

    Carmack, E. C.; Yamamoto-Kawai, M.; Haine, T. W. N.; Bacon, S.; Bluhm, B. A.; Lique, C.; Melling, H.; Polyakov, I. V.; Straneo, F.; Timmermans, M.-L.; Williams, W. J.

    2016-03-01

    The Arctic Ocean is a fundamental node in the global hydrological cycle and the ocean's thermohaline circulation. We here assess the system's key functions and processes: (1) the delivery of fresh and low-salinity waters to the Arctic Ocean by river inflow, net precipitation, distillation during the freeze/thaw cycle, and Pacific Ocean inflows; (2) the disposition (e.g., sources, pathways, and storage) of freshwater components within the Arctic Ocean; and (3) the release and export of freshwater components into the bordering convective domains of the North Atlantic. We then examine physical, chemical, or biological processes which are influenced or constrained by the local quantities and geochemical qualities of freshwater; these include stratification and vertical mixing, ocean heat flux, nutrient supply, primary production, ocean acidification, and biogeochemical cycling. Internal to the Arctic the joint effects of sea ice decline and hydrological cycle intensification have strengthened coupling between the ocean and the atmosphere (e.g., wind and ice drift stresses, solar radiation, and heat and moisture exchange), the bordering drainage basins (e.g., river discharge, sediment transport, and erosion), and terrestrial ecosystems (e.g., Arctic greening, dissolved and particulate carbon loading, and altered phenology of biotic components). External to the Arctic freshwater export acts as both a constraint to and a necessary ingredient for deep convection in the bordering subarctic gyres and thus affects the global thermohaline circulation. Geochemical fingerprints attained within the Arctic Ocean are likewise exported into the neighboring subarctic systems and beyond. Finally, we discuss observed and modeled functions and changes in this system on seasonal, annual, and decadal time scales and discuss mechanisms that link the marine system to atmospheric, terrestrial, and cryospheric systems.

  7. Dazzled by Ice and Snow: Improving Medium Spatial Resolution Ocean Color Images in Arctic Waters

    Science.gov (United States)

    Goyens, Clemence; Belanger, Simon; Babin, Marcel

    2016-08-01

    Ocean color sensors carried on-board satellites represent a valuable tool providing synoptic views of extreme environments such as the Arctic Ocean. However, in icy waters inaccuracies are frequent due to, among others, adjacent and sub-pixel sea-ice contamination. Therefore, there is a need to improve atmospheric correction (AC) algorithms to ensure accurate ocean color images in the vicinity of the ice edge. The present study compares the performance of different AC methods through an in-situ-satellite match-up exercise and investigates the possibility to improve these algorithms in presence of sea-ice floes. Results confirm the large errors resulting from sea-ice contamination and illustrate the difficulty in improving these algorithms due to, among others, the optically complex waters encountered in the Arctic Ocean.

  8. Variation of diffuse attenuation coefficient of downwelling irradiance in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    WANG Weibo; ZHAO Jinping

    2014-01-01

    The diffuse attenuation coefficient (Kd) for downwelling irradiance is calculated from solar irradiance data measured in the Arctic Ocean during 3rd and 4th Chinese National Arctic Research Expedition (CHINARE), including 18 stations and nine stations selected for irradiance profiles in sea water respectively. In this study, the variation of attenuation coefficient in the Arctic Ocean was studied, and the following results were ob-tained. First, the relationship between attenuation coefficient and chlorophyll concentration in the Arctic Ocean has the form of a power function. The best fit is at 443 nm, and its determination coefficient is more than 0.7. With increasing wavelength, the determination coefficient decreases abruptly. At 550 nm, it even reaches a value lower than 0.2. However, the exponent fitted is only half of that adapted in low-latitude ocean because of the lower chlorophyll-specific absorption in the Arctic Ocean. The upshot was that, in the case of the same chlorophyll concentration, the attenuation caused by phytoplankton chlorophyll in the Arctic Ocean is lower than in low-latitude ocean. Second, the spectral model, which exhibits the relationship of attenuation coefficients between 490 nm and other wavelength, was built and provided a new method to estimate the attenuation coefficient at other wavelength, if the attenuation coefficient at 490 nm was known. Third, the impact factors on attenuation coefficient, including sea ice and sea water mass, were discussed. The influence of sea ice on attenuation coefficient is indirect and is determined through the control of enter-ing solar radiation. The linear relationship between averaging sea ice concentration (ASIC, from 158 Julian day to observation day) and the depth of maximum chlorophyll is fitted by a simple linear equation. In addition, the sea water mass, such as the ACW (Alaskan Coastal Water), directly affects the amount of chlo-rophyll through taking more nutrient, and results in the

  9. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    Science.gov (United States)

    Barry, R. G.; Newell, J. P.; Schweiger, A.; Crane, R. G.

    1986-01-01

    A set of cloud cover data were developed for the Arctic during the climatically important spring/early summer transition months. Parallel with the determination of mean monthly cloud conditions, data for different synoptic pressure patterns were also composited as a means of evaluating the role of synoptic variability on Arctic cloud regimes. In order to carry out this analysis, a synoptic classification scheme was developed for the Arctic using an objective typing procedure. A second major objective was to analyze model output of pressure fields and cloud parameters from a control run of the Goddard Institue for Space Studies climate model for the same area and to intercompare the synoptic climatatology of the model with that based on the observational data.

  10. Moderate-resolution sea surface temperature data and seasonal pattern analysis for the Arctic Ocean ecoregions

    Science.gov (United States)

    Payne, Meredith C.; Reusser, Deborah A.; Lee, Henry

    2012-01-01

    Sea surface temperature (SST) is an important environmental characteristic in determining the suitability and sustainability of habitats for marine organisms. In particular, the fate of the Arctic Ocean, which provides critical habitat to commercially important fish, is in question. This poses an intriguing problem for future research of Arctic environments - one that will require examination of long-term SST records. This publication describes and provides access to an easy-to-use Arctic SST dataset for ecologists, biogeographers, oceanographers, and other scientists conducting research on habitats and/or processes in the Arctic Ocean. The data cover the Arctic ecoregions as defined by the "Marine Ecoregions of the World" (MEOW) biogeographic schema developed by The Nature Conservancy as well as the region to the north from approximately 46°N to about 88°N (constrained by the season and data coverage). The data span a 29-year period from September 1981 to December 2009. These SST data were derived from Advanced Very High Resolution Radiometer (AVHRR) instrument measurements that had been compiled into monthly means at 4-kilometer grid cell spatial resolution. The processed data files are available in ArcGIS geospatial datasets (raster and point shapefiles) and also are provided in text (.csv) format. All data except the raster files include attributes identifying latitude/longitude coordinates, and realm, province, and ecoregion as defined by the MEOW classification schema. A seasonal analysis of these Arctic ecoregions reveals a wide range of SSTs experienced throughout the Arctic, both over the course of an annual cycle and within each month of that cycle. Sea ice distribution plays a major role in SST regulation in all Arctic ecoregions.

  11. Arctic geodynamics: Continental shelf and deep ocean geophysics. ERS-1 satellite altimetry: A first look

    Science.gov (United States)

    Anderson, Allen Joel; Sandwell, David T.; Marquart, Gabriele; Scherneck, Hans-Georg

    1993-01-01

    An overall review of the Arctic Geodynamics project is presented. A composite gravity field model of the region based upon altimetry data from ERS-1, Geosat, and Seasat is made. ERS-1 altimetry covers unique Arctic and Antarctic latitudes above 72 deg. Both areas contain large continental shelf areas, passive margins, as well as recently formed deep ocean areas. Until ERS-1 it was not possible to study these areas with satellite altimetry. Gravity field solutions for the Barents sea, portions of the Arctic ocean, and the Norwegian sea north of Iceland are shown. The gravity anomalies around Svalbard (Spitsbergen) and Bear island are particularly large, indicating large isostatic anomalies which remain from the recent breakup of Greenland from Scandinavian. Recently released gravity data from the Armed Forces Topographic Service of Russia cover a portion of the Barents and Kara seas. A comparison of this data with the ERS-1 produced gravity field is shown.

  12. Quaternary paleoceanography of the central Arctic based on Integrated Ocean Drilling Program Arctic Coring Expedition 302 foraminiferal assemblages

    Science.gov (United States)

    Cronin, T. M.; Smith, S.A.; Eynaud, F.; O'Regan, M.; King, J.

    2008-01-01

    The Integrated Ocean Drilling Program (IODP) Arctic Coring Expedition (ACEX) Hole 4C from the Lomonosov Ridge in the central Arctic Ocean recovered a continuous 18 in record of Quaternary foraminifera yielding evidence for seasonally ice-free interglacials during the Matuyama, progressive development of large glacials during the mid-Pleistocene transition (MPT) ???1.2-0.9 Ma, and the onset of high-amplitude 100-ka orbital cycles ???500 ka. Foraminiferal preservation in sediments from the Arctic is influenced by primary (sea ice, organic input, and other environmental conditions) and secondary factors (syndepositional, long-term pore water dissolution). Taking these into account, the ACEX 4C record shows distinct maxima in agglutinated foraminiferal abundance corresponding to several interglacials and deglacials between marine isotope stages (MIS) 13-37, and although less precise dating is available for older sediments, these trends appear to continue through the Matuyama. The MPT is characterized by nearly barren intervals during major glacials (MIS 12, 16, and 22-24) and faunal turnover (MIS 12-24). Abundant calcareous planktonic (mainly Neogloboquadrina pachyderma sin.) and benthic foraminifers occur mainly in interglacial intervals during the Brunhes and very rarely in the Matuyama. A distinct faunal transition from calcareous to agglutinated foraminifers 200-300 ka in ACEX 4C is comparable to that found in Arctic sediments from the Lomonosov, Alpha, and Northwind ridges and the Morris Jesup Rise. Down-core disappearance of calcareous taxa is probably related to either reduced sea ice cover prior to the last few 100-ka cycles, pore water dissolution, or both. Copyright 2008 by the American Geophysical Union.

  13. Extensive under-ice turbulence microstructure measurements in the central Arctic Ocean in 2015

    Science.gov (United States)

    Rabe, Benjamin; Janout, Markus; Graupner, Rainer; Hoelemann, Jens; Hampe, Hendrik; Hoppmann, Mario; Horn, Myriel; Juhls, Bennet; Korhonen, Meri; Nikolopoulos, Anna; Pisarev, Sergey; Randelhoff, Achim; Savy, John-Philippe; Villacieros, Nicolas

    2016-04-01

    The Arctic Ocean is a strongly stratified low-energy environment, where tides are weak and the upper ocean is protected by an ice cover during much of the year. Interior mixing processes are dominated by double diffusion. The upper Arctic Ocean features a cold surface mixed layer, which, separated by a sharp halocline, protects the sea ice from the warmer underlying Atlantic- and Pacific-derived water masses. These water masses carry nutrients that are important for the Arctic ecosystem. Hence vertical fluxes of heat, salt, and nutrients are crucial components in understanding the Arctic ecosystem. Yet, direct flux measurements are difficult to obtain and hence sparse. In 2015, two multidisciplinary R/V Polarstern expeditions to the Arctic Ocean resulted in a series of under-ice turbulence microstructure measurements. These cover different locations across the Eurasian and Makarov Basins, during the melt season in spring and early summer as well as during freeze-up in late summer. Sampling was carried out from ice floes with repeated profiles resulting in 4-24 hour-long time series. 2015 featured anomalously warm atmospheric conditions during summer followed by unusually low temperatures in September. Our measurements show elevated dissipation rates at the base of the mixed layer throughout all stations, with significantly higher levels above the Eurasian continental slope when compared with the Arctic Basin. Additional peaks were found between the mixed layer and the halocline, in particular at stations where Pacific Summer water was present. This contribution provides first flux estimates and presents first conclusions regarding the impact of atmospheric and sea ice conditions on vertical mixing in 2015.

  14. Wide Distribution of Closely Related, Antibiotic-Producing Arthrobacter Strains throughout the Arctic Ocean

    DEFF Research Database (Denmark)

    Wietz, Matthias; Månsson, Maria; Bowman, Jeff S.

    2012-01-01

    We isolated 16 antibiotic-producing bacterial strains throughout the central Arctic Ocean, including seven Arthrobacter spp. with almost identical 16S rRNA gene sequences. These strains were numerically rare, as revealed using 454 pyrosequencing libraries. Arthrobacter spp. produced arthrobacilins...

  15. Eddy length scales and the Rossby radius in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    A. J. G. Nurser

    2013-10-01

    Full Text Available The first (and second baroclinic deformation (or Rossby radii are presented and discussed north of ~60° N, focusing on deep basins and shelf seas in the high Arctic Ocean, the Nordic Seas, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago, derived from high-resolution ice-ocean general circulation model output. Comparison of the model output with measured results shows that low values of the Rossby radius (in shallow water and high values (in the Canada Basin are accurately reproduced, while intermediate values (in the region of the Makarov and Amundsen Basins are overestimated. In the high Arctic Ocean, the first Rossby radius increases from ~5 km in the Nansen Basin to ~15 km in the central Canadian Basin. In the shelf seas and elsewhere, values are low (1–7 km, reflecting weak density stratification, shallow water, or both. Seasonality only strongly impacts the Rossby radii in shallow seas where winter homogenisation of the water column can reduce it to the order of 100 m. We also offer an interpretation and explanation of the observed scales of Arctic Ocean eddies.

  16. Analysis of seawater circulation and radioactive concentration in the whole Arctic Ocean

    Science.gov (United States)

    Ochiai, Minoru; Wada, Akira; Takano, Tairyu

    The results of research on marine contamination in the regional areas (the Kara and Barents Seas) in the Arctic Ocean were reported at the Journal of the Japan Society for Marine Survey and Technology, Vol. 15(2). In the present research, the authors carried out flow analysis and concentration analysis of radioactive materials in the whole region of the Arctic Ocean, based on the release scenario. A numerical hybrid box model was developed. The results obtained agreed with the observed features in many respects. Especially, stream flows in Norwegian, Barents Sea and Kara Sea showed fairly realistic features. The flow field in the surface layer in the central Arctic Ocean agreed with that in previously known data. In nuclide dispersion model, nuclide decay, mixing, scavenging and interaction between seawater and bottom sediment layers were taken into consideration in order to improve accuracy of the dosage estimate. Based on nuclide (Pu-239 and Cs-137) release scenarios, the whole Arctic Ocean was subjected to analysis. A clear difference was recognized in the diffusion distribution according to the properties of nuclides, and concentration in the sediment is one or two orders higher than that in the seawater when the distribution factor of Kd value is large as in Pu-239.

  17. Photosynthetic production in the central Arctic Ocean during the record sea-ice minimum in 2012

    NARCIS (Netherlands)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-01-01

    The ice-covered central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primar

  18. Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007

    NARCIS (Netherlands)

    Bauch, D.; Rutgers van der Loeff, M.; Andersen, N.; Torres-Valdes, S.; Bakker, K.; Abrahamsen, E.Povl

    2011-01-01

    Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and delta O-18 dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of de

  19. Effect of the East Siberian barrier on the echinoderm dispersal in the Arctic Ocean

    Science.gov (United States)

    Mironov, A. N.; Dilman, A. B.

    2010-06-01

    The distributional patterns were analyzed for 43 species and 33 genera of echinoderms in the Laptev and East Siberian seas and for 59 species and 35 genera of the asteroid species in the Arctic Ocean. The probable colonization route through the Arctic was suggested for each species based on (1) the distributional patterns of the Arctic species, (2) the distributional patterns of the closely related species, and (3) the location of the center of the diversity of the species belonging to a certain genus. The species of the Pacific origin prevailed in the asteroid fauna of the Arctic seas. The asteroid species diversity and the ratio of the species of Pacific origin decreased from the Barents towards the Laptev Sea and increased, respectively, in the East Siberian and the Chukchee seas. The species range limits were found for 19 species in the East Siberian Sea compared to only 3 species in the Laptev Sea. The East Siberian Sea was a limiting area for the dispersal of four species groups: (1) invaders from the North Pacific dispersing along the Asian coast of the Arctic (shallow-water stenobathic species), (2) invaders from the North Pacific dispersing along the American coast of the Arctic and further on back into the Arctic along the Eurasian coast (secondarily Atlantic species); (3) originally invaders from the Northern Atlantic; (4) representatives of the Arctic autochthonous fauna. A great width of the biotic boundaries (i.e., the zones of the species range boundaries crowding) was typical for the Arctic Basin, which was a sign of their young geological age.

  20. Short Communication: Atmospheric moisture transport, the bridge between ocean evaporation and Arctic ice melting

    Directory of Open Access Journals (Sweden)

    L. Gimeno

    2015-06-01

    Full Text Available If we could choose a region where the effects of global warming are likely to be pronounced and considerable, and at the same time one where the changes could affect the global climate in similarly asymmetric way with respect to other regions, this would unequivocally be the Arctic. The atmospheric branch of the hydrological cycle lies behind the linkages between the Arctic system and the global climate. Changes in the atmospheric moisture transport have been proposed as a vehicle for interpreting the most significant changes in the Arctic region. This is because the transport of moisture from the extratropical regions to the Arctic has increased in recent decades, and is expected to increase within a warming climate. This increase could be due either to changes in circulation patterns which have altered the moisture sources, or to changes in the intensity of the moisture sources because of enhanced evaporation, or a combination of these two mechanisms. In this short communication we focus on the assessing more objectively the strong link between ocean evaporation trends and Arctic Sea ice melting. We will critically analyze several recent results suggesting links between moisture transport and the extent of sea-ice in the Arctic, this being one of the most distinct indicators of continuous climate change both in the Arctic and on a global scale. To do this we will use a sophisticated Lagrangian approach to develop a more robust framework on some of these previous disconnect ng results, using new information and insights. Among the many mechanisms that could be involved are hydrological (increased Arctic river discharges, radiative (increase of cloud cover and water vapour and meteorological (increase in summer storms crossing the Arctic, or increments in precipitation.

  1. Impact of rapid sea-ice reduction in the Arctic Ocean on the rate of ocean acidification

    Directory of Open Access Journals (Sweden)

    A. Yamamoto

    2011-10-01

    Full Text Available The largest pH decline and widespread undersaturation with respect to aragonite in this century due to uptake of anthropogenic carbon dioxide in the Arctic Ocean have been projected. The reductions in pH and aragonite saturation state have been caused primarily by an increase in the concentration of atmospheric carbon dioxide. However, in a previous study, simulations with and without warming showed that these reductions in the Arctic Ocean also advances due to the melting of sea ice caused by global warming. Therefore, future projections of pH and aragonite saturation in the Arctic Ocean will be affected by how rapidly the reduction in sea ice occurs. In this study, the impact of sea-ice reduction rate on projected pH and aragonite saturation state in the Arctic surface waters was investigated. Reductions in pH and aragonite saturation were calculated from the outputs of two versions of an earth system model (ESM with different sea-ice reduction rates under similar CO2 emission scenarios. The newer model version projects that Arctic summer ice-free condition will be achieved by the year 2040, and the older version predicts ice-free condition by 2090. The Arctic surface water was projected to be undersaturated with respect to aragonite in the annual mean when atmospheric CO2 concentration reached 480 (550 ppm in year 2040 (2048 in new (old version. At an atmospheric CO2 concentration of 520 ppm, the maximum differences in pH and aragonite saturation state between the two versions were 0.08 and 0.15, respectively. The analysis showed that the decreases in pH and aragonite saturation state due to rapid sea-ice reduction were caused by increases in both CO2 uptake and freshwater input. Thus, the reductions in pH and aragonite saturation state in the Arctic surface waters are significantly affected by the difference in future projections for sea-ice reduction rate. The critical CO2 concentration

  2. Internal modes of multidecadal variability in the Arctic Ocean

    NARCIS (Netherlands)

    Frankcombe, L.M.; Dijkstra, H.A.

    2010-01-01

    Observations of sea ice extent and atmospheric temperature in the Arctic, although sparse, indicate variability on multidecadal time scales. A recent analysis of one of the global climate models [the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (CM2.1)] in the Fourth Assessment R

  3. Arctic and N Atlantic Crustal Thickness and Oceanic Lithosphere Distribution from Gravity Inversion

    Science.gov (United States)

    Kusznir, Nick; Alvey, Andy

    2014-05-01

    The ocean basins of the Arctic and N. Atlantic formed during the Mesozoic and Cenozoic as a series of distinct ocean basins, both small and large, leading to a complex distribution of oceanic crust, thinned continental crust and rifted continental margins. The plate tectonic framework of this region was demonstrated by the pioneering work of Peter Ziegler in AAPG Memoir 43 " Evolution of the Arctic-North Atlantic and the Western Tethys" published in 1988. The spatial evolution of Arctic Ocean and N Atlantic ocean basin geometry and bathymetry are critical not only for hydrocarbon exploration but also for understanding regional palaeo-oceanography and ocean gateway connectivity, and its influence on global climate. Mapping crustal thickness and oceanic lithosphere distribution represents a substantial challenge for the Polar Regions. Using gravity anomaly inversion we have produced comprehensive maps of crustal thickness and oceanic lithosphere distribution for the Arctic and N Atlantic region, We determine Moho depth, crustal basement thickness, continental lithosphere thinning and ocean-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction (Chappell & Kusznir 2008). Gravity anomaly and bathymetry data used in the gravity inversion are from the NGA (U) Arctic Gravity Project and IBCAO respectively; sediment thickness is from a new regional compilation. The resulting maps of crustal thickness and continental lithosphere thinning factor are used to determine continent-ocean boundary location and the distribution of oceanic lithosphere. Crustal cross-sections using Moho depth from the gravity inversion allow continent-ocean transition structure to be determined and magmatic type (magma poor, "normal" or magma rich). Our gravity inversion predicts thin crust and high continental lithosphere thinning factors in the Eurasia, Canada, Makarov, Podvodnikov and Baffin Basins

  4. A mass budget for mercury and methylmercury in the Arctic Ocean

    Science.gov (United States)

    Soerensen, Anne L.; Jacob, Daniel J.; Schartup, Amina T.; Fisher, Jenny A.; Lehnherr, Igor; St. Louis, Vincent L.; Heimbürger, Lars-Eric; Sonke, Jeroen E.; Krabbenhoft, David P.; Sunderland, Elsie M.

    2016-04-01

    Elevated biological concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, are observed throughout the Arctic Ocean, but major sources and degradation pathways in seawater are not well understood. We develop a mass budget for mercury species in the Arctic Ocean based on available data since 2004 and discuss implications and uncertainties. Our calculations show that high total mercury (Hg) in Arctic seawater relative to other basins reflect large freshwater inputs and sea ice cover that inhibits losses through evasion. We find that most net MeHg production (20 Mg a-1) occurs in the subsurface ocean (20-200 m). There it is converted to dimethylmercury (Me2Hg: 17 Mg a-1), which diffuses to the polar mixed layer and evades to the atmosphere (14 Mg a-1). Me2Hg has a short atmospheric lifetime and rapidly degrades back to MeHg. We postulate that most evaded Me2Hg is redeposited as MeHg and that atmospheric deposition is the largest net MeHg source (8 Mg a-1) to the biologically productive surface ocean. MeHg concentrations in Arctic Ocean seawater are elevated compared to lower latitudes. Riverine MeHg inputs account for approximately 15% of inputs to the surface ocean (2.5 Mg a-1) but greater importance in the future is likely given increasing freshwater discharges and permafrost melt. This may offset potential declines driven by increasing evasion from ice-free surface waters. Geochemical model simulations illustrate that for the most biologically relevant regions of the ocean, regulatory actions that decrease Hg inputs have the capacity to rapidly affect aquatic Hg concentrations.

  5. Towards improved estimation of the dynamic topography and ocean circulation in the high latitude and arctic ocean: The importance of GOCE

    DEFF Research Database (Denmark)

    Johannessen, J. A.; Raj, R. P.; Nilsen, J. E. Ø.

    2013-01-01

    The Arctic plays a fundamental role in the climate system and shows significant sensitivity to anthropogenic climate forcing and the ongoing climate change. Evidently changes in the Arctic and surrounding seas have far reaching influences on regional and global environment and climate variability...... dynamic topography for studies of the ocean circulation and transport estimates in the Nordic Seas and Arctic Ocean.......The Arctic plays a fundamental role in the climate system and shows significant sensitivity to anthropogenic climate forcing and the ongoing climate change. Evidently changes in the Arctic and surrounding seas have far reaching influences on regional and global environment and climate variability....... In this respect this study combines in-situ hydrographical data, surface drifter data and direct current meter measurements, with coupled sea ice - ocean models, radar altimeter data and the latest GOCE-based geoid in order to estimate and assess the quality, usefulness and validity of the new GOCE derived mean...

  6. Atmospheric Black Carbon along a Cruise Path through the Arctic Ocean during the Fifth Chinese Arctic Research Expedition

    OpenAIRE

    2014-01-01

    From July to September 2012, during the fifth Chinese National Arctic Research Expedition (CHINARE), the concentrations of black carbon (BC) aerosols inside the marine boundary layer were measured by an in situ aethalometer. BC concentrations ranged from 0.20 ng∙m−3 to 1063.20 ng∙m−3, with an average of 75.74 ng∙m−3. The BC concentrations were significantly higher over the mid-latitude and coastal areas than those over the remote ocean and high latitude areas. The highest average concentratio...

  7. Arctic Ocean: is it a sink or a source of atmospheric mercury?

    Science.gov (United States)

    Dastoor, Ashu P; Durnford, Dorothy A

    2014-01-01

    High levels of mercury in marine mammals threaten the health of Arctic inhabitants. Whether the Arctic Ocean (AO) is a sink or a source of atmospheric mercury is unknown. Given the paucity of observations in the Arctic, models are useful in addressing this question. GEOS-Chem and GRAHM, two complex numerical mercury models, present contrasting pictures of atmospheric mercury input to AO at 45 and 108 Mg yr(-1), respectively, and ocean evasion at 90 and 33 Mg yr(-1), respectively. We provide a comprehensive evaluation of GRAHM simulated atmospheric mercury input to AO using mercury observations in air, precipitation and snowpacks, and an analysis of the discrepancy between the two modeling estimates using observations. We discover two peaks in high-latitude summertime concentrations of atmospheric mercury. We show that the first is caused mainly by snowmelt revolatilization and the second by AO evasion of mercury. Riverine mercury export to AO is estimated at 50 Mg yr(-1) based on measured DOC export and at 15.5-31 Mg yr(-1) based on simulated mercury in meltwater. The range of simulated mercury fluxes to and from AO reflects uncertainties in modeling mercury in the Arctic; comprehensive observations in all compartments of the Arctic ecosystem are needed to close the gap.

  8. Assessing the added value of the recent declaration on unregulated fishing for sustainable governance of the central Arctic Ocean

    DEFF Research Database (Denmark)

    Shephard, Grace Elizabeth; Dalen, Kari; Peldszus, Regina

    2016-01-01

    The ‘Declaration concerning the prevention of unregulated high seas fishing in the central Arctic Ocean’ signed by the Arctic 5 nations, limits unregulated high seas fishing in the central part of the Arctic Ocean, and holds potential social, economic and political impacts for numerous stakeholders....... In this paper, the four Interim Measures in the Declaration are discussed and what value these measures bring beyond the existing international agreements is explored. It is found that even though the Declaration fills a gap in the management of potential fish stocks in the central Arctic Ocean, adopts...... understanding of the fisheries as well as the broader Arctic environment. Furthermore, the research generated by this measure will provide an important decision base for both regulation and management of human activity in the Arctic....

  9. {sup 236}U and {sup 129}I as tracers of water masses in the Arctic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Casacuberta, Nuria; Christl, Marcus; Vockenhuber, Christof; Synal, Hans-Arno [Laboratory of Ion Beam Physics, ETH-Zurich (Switzerland); Walther, Clemens [Institut fuer Radiooekologie und Strahlenschutz, Leibniz Universitaet Hannover (Germany); Loeff, Michiel van der [AWI-Geochemistry, Alfred Wegener Institut Fuer Polar und Meeresforshung, Bremerhaven (Germany); Masque, Pere [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, Bellaterra (Spain)

    2014-07-01

    Recently {sup 236}U attested to be a new transient oceanographic tracer: it is conservative in seawater and far from having reached steady state in the oceans. Its main sources in the North Atlantic are global fallout and European reprocessing plants. In this study, concentrations of {sup 236}U and {sup 129}I of eight deep profiles in the Arctic Ocean collected in 2011-2012 were determined with a compact ETH Zurich AMS system (TANDY). Results on {sup 236}U/{sup 238}U show a steep gradient, from the lowest ever-reported {sup 236}U/{sup 238}U atomic ratio in open ocean water (5±5) x 10{sup -12} up to (3700±80) x 10{sup -12}. Whereas the very low ratios are indicative for deep old waters, high ratios in shallow and surface waters show a clear signature of Atlantic Waters (AW) penetrating to the Arctic Ocean. The combination of {sup 236}U with {sup 129}I, both being released by the nuclear reprocessing plants of Sellafield and La Hague, with a distinct temporal input function, is used to estimate transit time of AW distributions in the Arctic Ocean.

  10. Overarching perspectives of contemporary and future ecosystems in the Arctic Ocean

    Science.gov (United States)

    Wassmann, Paul

    2015-12-01

    The Arctic region has a number of specific characteristics that provide the region an exceptional global position. It comprises 5% of the earth surface, 1% of world ocean volume, 3% of world ocean area, 25% of world continental shelf, 35% of world coastline, 11% of global river runoff and 20 of worlds 100 longest rivers. The Arctic region encompasses only 0.05% of the global population, but 22% undiscovered petroleum, 15% of global petroleum production, many metals and non-metals resources and support major global fisheries (60 and 80°N). In times of increasing resource demand and limitation the world focuses increasingly onto the Arctic Ocean (AO) and adjacent regions. This development is emphasised by the recent awareness of rapid climate change in the AO, the most significant on the globe, and has resulted in increased attention to the oceanography of the high north. The loss of Arctic sea ice has emerged as a leading signal of global warming. It is taking place at a rate 2-3 times faster than global rates and sea-ice cover has decreased more than 10% per decade, while sea-ice volume may have been reduced by minimum 40% over the last 30 years (Meier et al., 2014). The reduction of ice cover and thickness makes the region available for commercial interest. The region drives also critical effects on the biophysical, political and economic system of the Northern Hemisphere (e.g., Grambling, 2015). These striking changes in physical forcing have left marine ecological footprints of climate change in the Arctic ecosystem (Wassmann et al., 2011). However, predicting the future of the pan-Arctic ecosystem remains a challenge not only because of the ever-accelerating nature of both physical and biological alterations, but also because of lack of marine ecological knowledge, that is staggering for the majority of regions (except the Barents, Chukchi and Beaufort seas).

  11. Analysis of sea-level reconstruction techniques for the Arctic Ocean

    DEFF Research Database (Denmark)

    Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

    , these dedicated oceanographic missions are limited in coverage to between ±66° latitude, and satellite altimeter data at higher latitudes is of a substantially worse quality. Following the approach of Church et al. (2004), we apply a model based on empirical orthogonal functions (EOFs) to the Arctic Ocean...... of the model to reconstruct known data, in addition to the effects of regularization techniques and the relationship with climatological indices such as the Arctic Oscillation (AO). EOFs are obtained in a preliminary analysis from existing ocean models such as DRAKKAR, and from satellite data (from the ERS-1......Sea-level reconstructions spanning several decades have been examined in numerous studies for most of the world's ocean areas, where satellite missions such as TOPEX/Poseidon and Jason-1 and -2 have provided much-improved knowledge of variability and long-term changes in sea level. However...

  12. Surface salinity fields in the Arctic Ocean and statistical approaches to predicting anomalies and patterns

    CERN Document Server

    Chernyavskaya, Ekaterina A; Golden, Kenneth M; Timokhov, Leonid A

    2014-01-01

    Significant salinity anomalies have been observed in the Arctic Ocean surface layer during the last decade. Using gridded data of winter salinity in the upper 50 m layer of the Arctic Ocean for the period 1950-1993 and 2007-2012, we investigated the inter-annual variability of the salinity fields, attempted to identify patterns and anomalies, and developed a statistical model for the prediction of surface layer salinity. The statistical model is based on linear regression equations linking the principal components with environmental factors, such as atmospheric circulation, river runoff, ice processes, and water exchange with neighboring oceans. Using this model, we obtained prognostic fields of the surface layer salinity for the winter period 2013-2014. The prognostic fields demonstrated the same tendencies of surface layer freshening that were observed previously. A phase portrait analysis involving the first two principal components exhibits a dramatic shift in behavior of the 2007-2012 data in comparison ...

  13. Decrease in the CO2 uptake capacity in an ice-free Arctic Ocean basin.

    Science.gov (United States)

    Cai, Wei-Jun; Chen, Liqi; Chen, Baoshan; Gao, Zhongyong; Lee, Sang H; Chen, Jianfang; Pierrot, Denis; Sullivan, Kevin; Wang, Yongchen; Hu, Xinping; Huang, Wei-Jen; Zhang, Yuanhui; Xu, Suqing; Murata, Akihiko; Grebmeier, Jacqueline M; Jones, E Peter; Zhang, Haisheng

    2010-07-30

    It has been predicted that the Arctic Ocean will sequester much greater amounts of carbon dioxide (CO2) from the atmosphere as a result of sea ice melt and increasing primary productivity. However, this prediction was made on the basis of observations from either highly productive ocean margins or ice-covered basins before the recent major ice retreat. We report here a high-resolution survey of sea-surface CO2 concentration across the Canada Basin, showing a great increase relative to earlier observations. Rapid CO2 invasion from the atmosphere and low biological CO2 drawdown are the main causes for the higher CO2, which also acts as a barrier to further CO2 invasion. Contrary to the current view, we predict that the Arctic Ocean basin will not become a large atmospheric CO2 sink under ice-free conditions.

  14. Experiment of near surface layer parameters in ice camp over Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Estimates of near surface layer parameters over (78.) N drifting ice in ice camp over the Arctic ocean are made using bulk transfer methods with the data from the experiments operated by the Chinese Arctic Scientific Expedition in August 22 September 3, 2003.The results show that the net radiation received by the snow surface is only 3.6 W/m2, among which the main part transported into atmosphere in term of sensible heat and latent heat, which account for 52% and 31% respectively,and less part being transported to deep ice in the conductive process.The bulk transfer coefficient of momentum is about 1.16 x 10-3 in the near neutral layer, which is a little smaller than that obtained over (75.)N drifting ice.However, to compare with the results observed over 75°N drifting ice over the Arctic Ocean in 1999, it can be found that the thermodynamic and momentum of interactions between sea and air are significant different with latitudes, concentration and the scale of sea ice.It is very important on considering the effect of sea-air-ice interaction over the Arctic Ocean when studying climate modeling.

  15. Two regimes of the Arctic's circulation from ocean models with ice and contaminants.

    Science.gov (United States)

    Proshutinsky, A Y; Johnson, M

    2001-01-01

    A two-dimensional barotropic, coupled, ocean-ice model with a space resolution of 55.5 km and driven by atmospheric forces, river run-off, and sea-level slope between the Pacific and the Arctic Oceans, has been used to simulate the vertically averaged currents and ice drift in the Arctic Ocean. Results from 43 years of numerical simulations of water and ice motions demonstrate that two wind-driven circulation regimes are possible in the Arctic, a cyclonic and an anti-cyclonic circulation. These two regimes appear to alternate at 5-7 year intervals with the 10-15 year period. It is important to pollution studies to understand which circulation regime prevails at any time. It is anticipated that 1995 is a year with a cyclonic regime, and during this cyclonic phase and possibly during past cyclonic regimes as well, pollutants may reach the Alaskan shelf. The regime shifts demonstrated in this paper are fundamentally important to understanding the Arctic's general circulation and particularly important for estimating pollution transport.

  16. High variability of atmospheric mercury in the summertime boundary layer through the central Arctic Ocean.

    Science.gov (United States)

    Yu, Juan; Xie, Zhouqing; Kang, Hui; Li, Zheng; Sun, Chen; Bian, Lingen; Zhang, Pengfei

    2014-08-15

    The biogeochemical cycles of mercury in the Arctic springtime have been intensively investigated due to mercury being rapidly removed from the atmosphere. However, the behavior of mercury in the Arctic summertime is still poorly understood. Here we report the characteristics of total gaseous mercury (TGM) concentrations through the central Arctic Ocean from July to September, 2012. The TGM concentrations varied considerably (from 0.15 ng/m(3) to 4.58 ng/m(3)), and displayed a normal distribution with an average of 1.23 ± 0.61 ng/m(3). The highest frequency range was 1.0-1.5 ng/m(3), lower than previously reported background values in the Northern Hemisphere. Inhomogeneous distributions were observed over the Arctic Ocean due to the effect of sea ice melt and/or runoff. A lower level of TGM was found in July than in September, potentially because ocean emission was outweighed by chemical loss.

  17. Abundance and sinking of particulate black carbon in the western Arctic and Subarctic Oceans

    Science.gov (United States)

    Fang, Ziming; Yang, Weifeng; Chen, Min; Zheng, Minfang; Hu, Wangjiang

    2016-07-01

    The abundance and sinking of particulate black carbon (PBC) were examined for the first time in the western Arctic and Subarctic Oceans. In the central Arctic Ocean, high PBC concentrations with a mean of 0.021 ± 0.016 μmol L‑1 were observed in the marginal ice zone (MIZ). A number of parameters, including temperature, salinity and 234Th/238U ratios, indicated that both the rapid release of atmospherically deposited PBC on sea ice and a slow sinking rate were responsible for the comparable PBC concentrations between the MIZ and mid-latitudinal Pacific Ocean (ML). On the Chukchi and Bering Shelves (CBS), PBC concentrations were also comparable to those obtained in the ML. Further, significant deficits of 234Th revealed the rapid sinking of PBC on the CBS. These results implied additional source terms for PBC in addition to atmospheric deposition and fluvial discharge on the western Arctic shelves. Based on 234Th/238U disequilibria, the net sinking rate of PBC out of the surface water was ‑0.8 ± 2.5 μmol m‑3 d‑1 (mean ± s.d.) in the MIZ. In contrast, on the shelves, the average sinking rate of PBC was 6.1 ± 4.6 μmol m‑3 d‑1. Thus, the western Arctic Shelf was probably an effective location for burying PBC.

  18. Decadal Variability Shown by the Arctic Ocean Hydrochemical Data and Reproduced by an Ice-Ocean Model

    Institute of Scientific and Technical Information of China (English)

    M. Ikeda; R. Colony; H. Yamaguchi; T. Ikeda

    2005-01-01

    The Arctic is experiencing a significant warming trend as well as a decadal oscillation. The atmospheric circulation represented by the Polar Vortex and the sea ice cover show decadal variabilities, while it has been difficult to reveal the decadal oscillation from the ocean interior. The recent distribution of Russian hydrochemical data collected from the Arctic Basin provides useful information on ocean interior variabilities. Silicate is used to provide the most valuable data for showing the boundary between the silicate-rich Pacific Water and the opposite Atlantic Water. Here, it is assumed that the silicate distribution receives minor influence from seasonal biological productivity and Siberian Rivers outflow. It shows a clear maximum around 100m depth in the Canada Basin, along with a vertical gradient below 100 m, which provides information on the vertical motion of the upper boundary of the Atlantic Water at a decadal time scale. The boundary shifts upward (downward), as realized by the silicate reduction (increase) at a fixed depth, responding to a more intense (weaker) Polar Vortex or a positive (negative) phase of the Arctic Oscillation. A coupled ice-ocean model is employed to reconstruct this decadal oscillation.

  19. Arctic contribution to upper-ocean variability in the North Atlantic

    Science.gov (United States)

    Walsh, John E.; Chapman, William L.

    1990-01-01

    The potential climatic leverage of salinity and temperature anomalies in the high-latitude North Atlantic is large. Substantial variations of sea ice have accompanied North Atlantic salinity and temperature anomalies. Atmospheric pressure data are used here to show that the local forcing of high-latitude North Atlantic Ocean fluctuations is augmented by antecedent atmospheric circulation anomalies over the central Arctic. These circulation anomalies are consistent with enhanced wind-forcing of thicker older ice into the Transpolar Drift Stream and an enhanced export of sea ice (fresh water) from the Arctic into the Greenland Sea prior to major episodes of ice severity in the Greenland and Iceland seas.

  20. Ammonia-oxidizing Archaea in the Arctic Ocean and Antarctic coastal waters.

    Science.gov (United States)

    Kalanetra, Karen M; Bano, Nasreen; Hollibaugh, James T

    2009-09-01

    We compared abundance, distributions and phylogenetic composition of Crenarchaeota and ammonia-oxidizing Archaea (AOA) in samples collected from coastal waters west of the Antarctic Peninsula during the summers of 2005 and 2006, with samples from the central Arctic Ocean collected during the summer of 1997. Ammonia-oxidizing Archaea and Crenarchaeota abundances were estimated from quantitative PCR measurements of amoA and 16S rRNA gene abundances. Crenarchaeota and AOA were approximately fivefold more abundant at comparable depths in the Antarctic versus the Arctic Ocean. Crenarchaeota and AOA were essentially absent from the Antarctic Summer Surface Water (SSW) water mass (0-45 m depth). The ratio of Crenarchaeota 16S rRNA to archaeal amoA gene abundance in the Winter Water (WW) water mass (45-105 m depth) of the Southern Ocean was much lower (0.15) than expected and in sharp contrast to the ratio (2.0) in the Circumpolar Deep Water (CDW) water mass (105-3500 m depth) immediately below it. We did not observe comparable segregation of this ratio by depth or water mass in Arctic Ocean samples. A ubiquitous, abundant and polar-specific crenarchaeote was the dominant ribotype in the WW and important in the upper halocline of the Arctic Ocean. Our data suggest that this organism does not contain an ammonia monooxygenase gene. In contrast to other studies where Crenarchaeota populations apparently lacking amoA genes are found in bathypelagic waters, this organism appears to dominate in well-defined, ammonium-rich, near-surface water masses in polar oceans.

  1. The Eurasian and Makarov Basins target changes in the Arctic Ocean

    Science.gov (United States)

    Polyakov, I.; Padman, L.; Pnyushkov, A.; Rember, R.; Ivanov, V.; Lenn, Y. D.

    2015-12-01

    The Arctic Ocean interior is warming, and there is no indication that the rate of warming will decrease in the near future. The relative role of the interior ocean's warmth in setting net energy flux to, and the mass balance of, Arctic sea ice, however, is still under debate. Thus, quantifying this flux and understanding mechanisms for redistributing heat in the ocean interior are of particular importance. Warm (>0°C) intermediate-depth (150-900m) water of Atlantic origin (the so-called Atlantic Water, AW) is the major source of heat for the ocean interior. Ice thickness along the continental slope east of Svalbard is much less than that expected of first-year ice, suggesting that AW has a direct impact on sea ice just after entering the Arctic. However, in the Canadian Basin, far away from Fram Strait, overlying fresher and colder stable layers effectively insulate the upper mixed layer and ice from impacts of the AW heat. Even though the eastern Eurasian Basin (EEB) is separated from Fram Strait by hundreds of kilometers, the AW heat finds its ways for reaching the ice base in this part of the Arctic Ocean. A distinct process, double diffusion convection, plays an important role in vertical redistribution of AW heat in this region. Double diffusion convection is typically identified as a vertical sequence of almost-homogeneous convective layers separated by high-gradient interfaces, forming a double diffusive "staircase". The staircase structure is a consequence of the differing molecular diffusivities of heat and salt; surprisingly, even though molecular properties drive the instability, resulting net fluxes can be very large, up to several W/m2. The interaction of shear and diffusive layering can significantly alter the heat (and momentum) flux through a staircase. The existing data set are limited and further detailed process studies in the EEB targeting the unique mechanisms of oceanic heat exchange in the interior of the EEB are required.

  2. TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

    Directory of Open Access Journals (Sweden)

    P. Sakov

    2012-08-01

    Full Text Available We present a detailed description of TOPAZ4, the latest version of TOPAZ – a coupled ocean-sea ice data assimilation system for the North Atlantic Ocean and Arctic. It is the only operational, large-scale ocean data assimilation system that uses the ensemble Kalman filter. This means that TOPAZ features a time-evolving, state-dependent estimate of the state error covariance. Based on results from the pilot MyOcean reanalysis for 2003–2008, we demonstrate that TOPAZ4 produces a realistic estimate of the ocean circulation in the North Atlantic and the sea-ice variability in the Arctic. We find that the ensemble spread for temperature and sea-level remains fairly constant throughout the reanalysis demonstrating that the data assimilation system is robust to ensemble collapse. Moreover, the ensemble spread for ice concentration is well correlated with the actual errors. This indicates that the ensemble statistics provide reliable state-dependent error estimates – a feature that is unique to ensemble-based data assimilation systems. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when in-situ profiles below the ice in the Arctic Ocean are assimilated. We find that data assimilation improves the match to independent observations compared to a free model. Improvements are particularly noticeable for ice thickness, salinity in the Arctic, and temperature in the Fram Strait, but not for transport estimates or underwater temperature. At the same time, the pilot reanalysis has revealed several flaws in the system that have degraded its performance. Finally, we show that a simple bias estimation scheme can effectively detect the seasonal or constant bias in temperature and sea-level.

  3. Distribution of benthic foraminifers (>125 um) in the surface sediments of the Arctic Ocean

    Science.gov (United States)

    Osterman, Lisa E.; Poore, Richard Z.; Foley, Kevin M.

    1999-01-01

    Census data on benthic foraminifers (>125 ?m) in surface sediment samples from 49 box cores are used to define four depth-controlled biofacies, which will aid in the paleoceanographic reconstruction of the Arctic Ocean. The shelf biofacies contains a mix of shallow-water calcareous and agglutinated species from the continental shelves of the Beaufort and Chukchi Seas and reflects the variable sedimentologic and oceanic conditions of the Arctic shelves. The intermediate-depth calcareous biofacies, found between 500 and 1,100 meters water depth (mwd), contains abundant Cassidulina teretis , presumably indicating the influence of Atlantic-derived water at this depth. In water depths between 1,100 and 3,500 m, a deepwater calcareous biofacies contains abundant Oridorsalis umbonatus . Below 3,500 mwd, the deepwater mixed calcareous/agglutinated biofacies of the Canada, Makarov, and Eurasian Basins reflects a combination of low productivity, dissolution, and sediment transport. Two other benthic foraminiferal species show specific environmental preferences. Fontbotia wuellerstorfi has a depth distribution between 900 and 3,500 mwd, but maximum abundance occurs in the region of the Mendeleyev Ridge. The elevated abundance of F. wuellerstorfi may be related to increased food supply carried by a branch of Atlantic water that crosses the Lomonosov Ridge near the Russian Continental Shelf. Triloculina frigida is recognized to be a species preferring lower slope sediments commonly disturbed by turbidites and bottom currents. INTRODUCTION At present, our understanding of the Arctic Ocean lags behind our understanding of other oceans, and fundamental questions still exist about its role in and response to global climate change. The Arctic Ocean is particularly sensitive to climatic fluctuations because small changes in the amounts of sea-ice cover can alter global albedo and thermohaline circulation (Aagaard and Carmack, 1994). Numerous questions still exist regarding the nature

  4. Anthropogenic radioactivity in the Arctic Ocean--review of the results from the joint German project.

    Science.gov (United States)

    Nies, H; Harms, I H; Karcher, M J; Dethleff, D; Bahe, C

    1999-09-30

    The paper presents the results of the joint project carried out in Germany in order to assess the consequences in the marine environment from the dumping of nuclear wastes in the Kara and Barents Seas. The project consisted of experimental work on measurements of radionuclides in samples from the Arctic marine environment and numerical modelling of the potential pathways and dispersion of contaminants in the Arctic Ocean. Water and sediment samples were collected for determination of radionuclide such as 137Cs, 90Sr, 239 + 240Pu, 238Pu, and 241Am and various organic micropollutants. In addition, a few water and numerous surface sediment samples collected in the Kara Sea and from the Kola peninsula were taken by Russian colleagues and analysed for artificial radionuclide by the BSH laboratory. The role of transport by sea ice from the Kara Sea into the Arctic Ocean was assessed by a small subgroup at GEOMAR. This transport process might be considered as a rapid contribution due to entrainment of contaminated sediments into sea ice, following export from the Kara Sea into the transpolar ice drift and subsequent release in the Atlantic Ocean in the area of the East Greenland Current. Numerical modelling of dispersion of pollutants from the Kara and Barents Seas was carried out both on a local scale for the Barents and Kara Seas and for long range dispersion into the Arctic and Atlantic Oceans. Three-dimensional baroclinic circulation models were applied to trace the transport of pollutants. Experimental results were used to validate the model results such as the discharges from the nuclear reprocessing plant at Sellafield and subsequent contamination of the North Sea up the Arctic Seas.

  5. Ice-tethered profiler data collected in the Arctic Ocean and Southern Ocean from drifting ice, August 21, 2004 - January 10, 2013 (NODC Accession 0101472)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Recent studies indicate that the Arctic may be both a sensitive indicator and an active agent of climate variability and change. While progress has been made in...

  6. Optical characterisation of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean) and implications for ocean colour remote sensing

    Science.gov (United States)

    Doxaran, D.; Ehn, J.; Bélanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-08-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future

  7. Optical Characterisation of Suspended Particles in the Mackenzie River Plume (Canadian Arctic Ocean) and Implications for Ocean Colour Remote Sensing

    Science.gov (United States)

    Doxaran, D.; Ehn, J.; Belanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-01-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future

  8. Optical characterisation of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean and implications for ocean colour remote sensing

    Directory of Open Access Journals (Sweden)

    D. Doxaran

    2012-08-01

    Full Text Available Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational.

    The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM on the Mackenzie River continental shelf (Canadian Arctic Ocean using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC. Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow. Most of the seaward export of SPM is observed to occur within the west side of

  9. Influence of Sea Ice on the Thermohaline Circulation in the Arctic-North Atlantic Ocean

    Science.gov (United States)

    Mauritzen, Cecilie; Haekkinen, Sirpa

    1997-01-01

    A fully prognostic coupled ocean-ice model is used to study the sensitivity of the overturning cell of the Arctic-North-Atlantic system to sea ice forcing. The strength of the thermohaline cell will be shown to depend on the amount of sea ice transported from the Arctic to the Greenland Sea and further to the subpolar gyre. The model produces a 2-3 Sv increase of the meridional circulation cell at 25N (at the simulation year 15) corresponding to a decrease of 800 cu km in the sea ice export from the Arctic. Previous modeling studies suggest that interannual and decadal variability in sea ice export of this magnitude is realistic, implying that sea ice induced variability in the overturning cell can reach 5-6 Sv from peak to peak.

  10. Composition, Buoyancy Regulation and Fate of Ice Algal Aggregates in the Central Arctic Ocean

    DEFF Research Database (Denmark)

    Fernandez-Mendez, Mar; Wenzhöfer, Frank; Peeken, Ilka

    2014-01-01

    Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly...... seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central...... Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen...

  11. Atlantic-Arctic exchange in a series of ocean model simulations (CORE-II)

    Science.gov (United States)

    Roth, Christina; Behrens, Erik; Biastoch, Arne

    2014-05-01

    In this study we aim to improve the understanding of exchange processes between the North Atlantic and the Arctic Ocean. The Nordic Sea builds an important connector between these regions, by receiving and modifying warm and saline Atlantic waters, and by providing dense overflow as a backbone of the Atlantic Meridional Overturning Circulation (AMOC). Using a hierarchy of global ocean/sea-ice models, the specific role of the Nordic Seas, both providing a feedback with the AMOC, but also as a modulator of the Atlantic water flowing into the Arctic Ocean, is examined. The models have been performed under the CORE-II protocol, in which atmospheric forcing of the past 60 years was applied in a subsequent series of 5 iterations. During the course of this 300-year long integration, the AMOC shows substantial changes, which are correlated with water mass characteristics in the Denmark Strait overflow characteristics. Quantitative analyses using Lagrangian trajectories explore the impact of these trends on the Arctic Ocean through the Barents Sea and the Fram Strait.

  12. Ozone in the Boundary Layer air over the Arctic Ocean – measurements during the TARA expedition

    Directory of Open Access Journals (Sweden)

    J. W. Bottenheim

    2009-03-01

    Full Text Available A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N – 88° N latitude. The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June after Polar sunrise. At other times of the year ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30–40 nmol mol−1 and summer minima of ca. 20 nmol mol−1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above −20°C during most ODEs (ozone depletion episodes. Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads developed in the spring of 2007.

  13. Patterns and trends of macrobenthic abundance, biomass and production in the deep Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Renate Degen

    2015-08-01

    Full Text Available Little is known about the distribution and dynamics of macrobenthic communities of the deep Arctic Ocean. The few previous studies report low standing stocks and confirm a gradient with declining biomass from the slopes down to the basins, as commonly reported for deep-sea benthos. In this study, we investigated regional differences of faunal abundance and biomass, and made for the first time ever estimates of deep Arctic community production by using a multi-parameter artificial neural network model. The underlying data set combines data from recent field studies with published and unpublished data from the past 20 years, to analyse the influence of water depth, geographical latitude and sea-ice concentration on Arctic benthic communities. We were able to confirm the previously described negative relationship of macrofauna standing stock with water depth in the Arctic deep sea, while also detecting substantial regional differences. Furthermore, abundance, biomass and production decreased significantly with increasing sea-ice extent (towards higher latitudes down to values <200 ind m−2, <65 mg C m−2 and <73 mg C m−2 y−1, respectively. In contrast, stations under the seasonal ice zone regime showed much higher standing stock and production (up to 2500 mg C m−2 y−1, even at depths down to 3700 m. We conclude that particle flux is the key factor structuring benthic communities in the deep Arctic Ocean as it explains both the low values in the ice-covered Arctic basins and the higher values in the seasonal ice zone.

  14. Benthic macrofaunal production for a typical shelf-slope-basin region in the western Arctic Ocean

    Science.gov (United States)

    Lin, Heshan; Wang, Jianjun; Liu, Kun; He, Xuebao; Lin, Junhui; Huang, Yaqin; Zhang, Shuyi; Mou, Jianfeng; Zheng, Chengxing; Wang, Yu

    2016-02-01

    Secondary production by macrofaunal communities in the western Arctic Ocean were quantified during the 4th and 5th Chinese Arctic Scientific Expeditions. The total production and P/B ratio for each sector ranged from 3.8 (±7.9) to 615.6 (±635.5) kJ m-2 yr-1 and 0.5 (± 0.2) to 0.7 (± 0.2) yr-1, respectively. The shallow shelves in the western Arctic Ocean exhibited particularly high production (178.7-615.6 kJ m-2 yr-1), particularly in the two "hotspots" - the southern and northeastern (around Barrow Canyon) Chukchi Sea. Benthic macrofaunal production decreased sharply with depth and latitude along a shelf-slope-basin transect, with values of 17.0-269.8 kJ m-2 yr-1 in slope regions and 3.8-10.1 kJ m-2 yr-1 in basins. Redundancy analysis indicated that hydrological characteristics (depth, bottom temperature and salinity) and granulometric parameters (mean particle size, % sand and % clay) show significant positive/negative correlations with total production. These correlations revealed that the dominant factors influencing benthic production are the habitat type and food supply from the overlying water column. In the Arctic, the extreme environmental conditions and low temperature constrain macrofaunal metabolic processes, such that food and energy are primarily used to increase body mass rather than for reproduction. Hence, energy turnover is relatively low at high latitudes. These data further our understanding of benthic production processes and ecosystem dynamics in the context of rapid climate change in the western Arctic Ocean.

  15. Regional estimates of POC export flux derived from thorium-234 in the western Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; CHEN Min; QIU Yusheng; LI Yanping

    2005-01-01

    In order to elucidate the regional export variation of particulate organic carbon in the western Arctic Ocean, samples vertically integrated between 0 and 100 m depth or between 0and 30 m/40 m depth were collected for total 224Th measurements and those from 30 m/40 m or 100 m depth were collected for particulate 234Th measurements during the Second Chinese Arctic Expedition in July-September 2003. The removal fluxes and residence time of 234Th in the upper water column were calculated by using irreversible steady-state scavenging model. The results showed that, total 234Th was deficit relative to its parent 238U in the western Arctic Ocean except in the western Chukchi shelf and the slope regions around 160°W, indicating that scavenging and removal processes play an important role in element biogeochemical cycle in the Arctic Ocean. In the western Chukchi shelfand the slope regions around 160°W,total 234Th was excess relative to 238U, ascribing to the horizontal input of 234Th adsorbed by ice-rafted sediments. Thorinm-234 removal fluxes decreased from the shelf to the deep ocean, while the residence time of 234Th increased from shelf to offshore, demonstrating that particle scavenging and removal processes are more active in the shelfregions. The estimated POC export fluxes from 40 m in the shelf regions and from 100 m in the slope and deep ocean varied between 1.6 and 27.5 mmol/(m2·d), and between 1.8 and 14.4 mmol/(m2·d), respectively. The averaged POC export fluxes over the entire water column decreased from the shelf to the deep ocean, indicating that the Chukchi shelf is an important region for organic carbon sequestration. The high ThE ratios (ratio of POC export flux derived from 234Th/238U disequilibria to primary production) in the western Arctic Ocean suggested that the biological pump runs actively in high-latitudes.

  16. Ocean optical measurements—II. Statistical analysis of data from Canadian eastern Arctic waters

    Science.gov (United States)

    Topliss, B. J.; Miller, J. R.; Horne, E. P. W.

    1989-02-01

    The attenuation of light in Arctic waters was found to be controlled by chlorophyll pigment and dissolved material with a possible contribution from suspended particulate matter. The potential dependence of the attenuation coefficient on pigment concentration, depth and material type was statistically investigated to evaluate these individual, but intercorrelated, contributions. When the variation of dissolved material with depth was selected as a separation criteria for the intercorrelated in situ variables the statistical analysis suggested a concentration dependence for the specific attenuation coefficient of chlorophyll pigments. A non-linear attenuation/pigment relationship for the Arctic data, governed by concentration and proportion of phaeophytin to chlorophyll, was found to be consistent with clear water data from the open ocean as well as from turbid waters on the Grand Banks. Although only approximately 25% of available light was absorbed by chlorophyll a pigment itself, the under-water spectrum was modified by these pigments in a manner similar to that occurring in clear open ocean waters. Scattering calculations gave large specific back-scattering values for low pigment concentrations in Arctic waters as well as for waters from an inshore glacial fjord, posing potential interpretation problems for remote sensing applications. In contrast scattering calculations for high pigment concentrations from the Arctic implied that potentially useful information might be extracted from high latitude imagery.

  17. Analyses of structure of planetary boundary layer in ice camp over Arctic ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September, 2003. It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night. The boundary layer can be described as vertical structures of stability, instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant, which causes stronger wind shear, temperature and humidity inversion with typical wind shear of 10 m/s/100 m, intensity of temperature inversion of 8 ℃/100 m. While the larger pack ice is broken by such process, new ice free area in the high latitudes of arctic ocean. The interactions between air/ice/water are enhanced. The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region.

  18. Effects of sea ice cover on satellite-detected primary production in the Arctic Ocean.

    Science.gov (United States)

    Kahru, Mati; Lee, Zhongping; Mitchell, B Greg; Nevison, Cynthia D

    2016-11-01

    The influence of decreasing Arctic sea ice on net primary production (NPP) in the Arctic Ocean has been considered in multiple publications but is not well constrained owing to the potentially large errors in satellite algorithms. In particular, the Arctic Ocean is rich in coloured dissolved organic matter (CDOM) that interferes in the detection of chlorophyll a concentration of the standard algorithm, which is the primary input to NPP models. We used the quasi-analytic algorithm (Lee et al 2002 Appl. Opti. 41, 5755-5772. (doi:10.1364/AO.41.005755)) that separates absorption by phytoplankton from absorption by CDOM and detrital matter. We merged satellite data from multiple satellite sensors and created a 19 year time series (1997-2015) of NPP. During this period, both the estimated annual total and the summer monthly maximum pan-Arctic NPP increased by about 47%. Positive monthly anomalies in NPP are highly correlated with positive anomalies in open water area during the summer months. Following the earlier ice retreat, the start of the high-productivity season has become earlier, e.g. at a mean rate of -3.0 d yr(-1) in the northern Barents Sea, and the length of the high-productivity period has increased from 15 days in 1998 to 62 days in 2015. While in some areas, the termination of the productive season has been extended, owing to delayed ice formation, the termination has also become earlier in other areas, likely owing to limited nutrients.

  19. Arctic surface temperatures from Metop AVHRR compared to in situ ocean and land data

    Directory of Open Access Journals (Sweden)

    G. Dybkjær

    2012-03-01

    Full Text Available The ice surface temperature (IST is an important boundary condition for both atmospheric and ocean and sea ice models and for coupled systems. An operational ice surface temperature product using satellite Metop AVHRR infra-red data was developed for MyOcean. The IST can be mapped in clear sky regions using a split window algorithm specially tuned for sea ice. Clear sky conditions are prevailing during spring in the Arctic while persistent cloud cover limits data coverage during summer. The cloud covered regions are detected using the EUMETSAT cloud mask. The Metop IST compares to 2 m temperature at the Greenland ice cap Summit within STD error of 3.14 °C and to Arctic drifting buoy temperature data within STD error of 3.69 °C. A case study reveal that the in situ radiometer data versus satellite IST STD error can be much lower (0.73 °C and that the different in situ measures complicates the validation. Differences and variability between Metop IST and in situ data are analysed and discussed. An inter-comparison of Metop IST, numerical weather prediction temperatures and in situ observation indicates large biases between the different quantities. Because of the scarcity of conventional surface temperature or surface air temperature data in the Arctic the satellite IST data with its relatively good coverage can potentially add valuable information to model analysis for the Arctic atmosphere.

  20. Assessing climate impacts and risks of ocean albedo modification in the Arctic

    Science.gov (United States)

    Mengis, N.; Martin, T.; Keller, D. P.; Oschlies, A.

    2016-05-01

    The ice albedo feedback is one of the key factors of accelerated temperature increase in the high northern latitudes under global warming. This study assesses climate impacts and risks of idealized Arctic Ocean albedo modification (AOAM), a proposed climate engineering method, during transient climate change simulations with varying representative concentration pathway (RCP) scenarios. We find no potential for reversing trends in all assessed Arctic climate metrics under increasing atmospheric CO2 concentrations. AOAM only yields an initial offset during the first years after implementation. Nevertheless, sea ice loss can be delayed by 25(60) years in the RCP8.5(RCP4.5) scenario and the delayed thawing of permafrost soils in the AOAM simulations prevents up to 40(32) Pg of carbon from being released by 2100. AOAM initially dampens the decline of the Atlantic Meridional Overturning and delays the onset of open ocean deep convection in the Nordic Seas under the RCP scenarios. Both these processes cause a subsurface warming signal in the AOAM simulations relative to the default RCP simulations with the potential to destabilize Arctic marine gas hydrates. Furthermore, in 2100, the RCP8.5 AOAM simulation diverts more from the 2005-2015 reference state in many climate metrics than the RCP4.5 simulation without AOAM. Considering the demonstrated risks, we conclude that concerning longer time scales, reductions in emissions remain the safest and most effective way to prevent severe changes in the Arctic.

  1. Arctic surface temperatures from Metop AVHRR compared to in situ ocean and land data

    Directory of Open Access Journals (Sweden)

    G. Dybkjær

    2012-11-01

    Full Text Available The ice surface temperature (IST is an important boundary condition for both atmospheric and ocean and sea ice models and for coupled systems. An operational ice surface temperature product using satellite Metop AVHRR infra-red data was developed for MyOcean. The IST can be mapped in clear sky regions using a split window algorithm specially tuned for sea ice. Clear sky conditions prevail during spring in the Arctic, while persistent cloud cover limits data coverage during summer. The cloud covered regions are detected using the EUMETSAT cloud mask. The Metop IST compares to 2 m temperature at the Greenland ice cap Summit within STD error of 3.14 °C and to Arctic drifting buoy temperature data within STD error of 3.69 °C. A case study reveals that the in situ radiometer data versus satellite IST STD error can be much lower (0.73 °C and that the different in situ measurements complicate the validation. Differences and variability between Metop IST and in situ data are analysed and discussed. An inter-comparison of Metop IST, numerical weather prediction temperatures and in situ observation indicates large biases between the different quantities. Because of the scarcity of conventional surface temperature or surface air temperature data in the Arctic, the satellite IST data with its relatively good coverage can potentially add valuable information to model analysis for the Arctic atmosphere.

  2. Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre

    OpenAIRE

    Giles, K. A.; Laxon, S. W.; Ridout, A. L.; Wingham, D. J.; S. Bacon

    2012-01-01

    The Arctic Ocean’s freshwater budget comprises contributions from river runoff, precipitation, evaporation, sea-ice and exchanges with the North Pacific and Atlantic. More than 70,000km3 of freshwater are stored in the upper layer of the Arctic Ocean, leading to low salinities in upper-layer Arctic sea water, separated by a strong halocline from warm, saline water beneath. Spatially and temporally limited observations show that the Arctic Ocean’s freshwater content has increased over the past...

  3. Control of primary production in the Arctic by nutrients and light: insights from a high resolution ocean general circulation model

    Directory of Open Access Journals (Sweden)

    E. E. Popova

    2010-07-01

    Full Text Available Until recently, the Arctic Basin was generally considered to be a low productivity area and was afforded little attention in global- or even basin-scale ecosystem modelling studies. Due to anthropogenic climate change however, the sea ice cover of the Arctic Ocean is undergoing an unexpectedly fast retreat, exposing increasingly large areas of the basin to sunlight. As indicated by existing Arctic phenomena such as ice-edge blooms, this decline in sea-ice is liable to encourage pronounced growth of phytoplankton in summer and poses pressing questions concerning the future of Arctic ecosystems. It thus provides a strong impetus to modelling of this region.

    The Arctic Ocean is an area where plankton productivity is heavily influenced by physical factors. As these factors are strongly responding to climate change, we analyse here the results from simulations of the 1/4° resolution global ocean NEMO (Nucleus for European Modelling of the Ocean model coupled with the MEDUSA (Model for Ecosystem Dynamics, carbon Utilisation, Sequestration and Acidification biogeochemical model, with a particular focus on the Arctic Basin. Simulated productivity is consistent with the limited observations for the Arctic, with significant production occurring both under the sea-ice and at the thermocline, locations that are difficult to sample in the field.

    Results also indicate that a substantial fraction of the variability in Arctic primary production can be explained by two key physical factors: (i the maximum penetration of winter mixing, which determines the amount of nutrients available for summer primary production, and (ii short-wave radiation at the ocean surface, which controls the magnitude of phytoplankton blooms. A strong empirical correlation was found in the model output between primary production these two factors, highlighting the importance of physical processes in the Arctic Ocean.

  4. Central Arctic atmospheric summer conditions during the Arctic Summer Cloud Ocean Study (ASCOS: contrasting to previous expeditions

    Directory of Open Access Journals (Sweden)

    M. Tjernström

    2012-02-01

    Full Text Available Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as that described in this paper: the Arctic Summer Cloud-Ocean Study (ASCOS. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this.

    To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as some key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean, the AOE-96, SHEBA and AOE-2001 expeditions.

    We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of

  5. Flux variations and vertical distributions of microzooplankton (Radiolaria in the western Arctic Ocean: environmental indices in a warming Arctic

    Directory of Open Access Journals (Sweden)

    T. Ikenoue

    2014-12-01

    Full Text Available The vertical distribution of radiolarians was investigated using a vertical multiple plankton sampler (100–0, 250–100, 500–250 and 1000–500 m water depths, 62 μm mesh size at the Northwind Abyssal Plain and southwestern Canada Basin in September 2013. To investigate seasonal variations in the flux of radiolarians in relation to sea-ice and water masses, time series sediment trap system was moored at Station NAP (75°00' N, 162°00' W, bottom depth 1975 m in the western Arctic Ocean during October 2010–September 2012. We showed characteristics of fourteen abundant radiolarian taxa related to the vertical hydrographic structure in the western Arctic Ocean. We found the Ceratocyrtis histricosus, a warm Atlantic water species, in net samples, indicating that it has extended its habitat into the Pacific Winter Water. The radiolarian flux was comparable to that in the North Pacific Oceans. Amphimelissa setosa was dominant during the open water and the beginning and the end of ice cover seasons with well-grown ice algae, ice fauna and with alternation of stable water masses and deep vertical mixing. During the sea-ice cover season, however, oligotrophic and cold-water tolerant Actinommidae was dominant and the productivity of radiolaria was lower and its species diversity was greater, which might be associated with the seasonal increase of solar radiation that induce the growth of algae on the ice and the other phytoplankton species under the sea-ice. These indicated that the dynamics of sea-ice was a major factor affecting the productivity, distribution, and composition of radiolarian fauna.

  6. Deep water paleo-iceberg scouring on top of Hovgaard Ridge-Arctic Ocean

    Science.gov (United States)

    Arndt, Jan Erik; Niessen, Frank; Jokat, Wilfried; Dorschel, Boris

    2014-07-01

    In multibeam echosounder and subbottom profiler data acquired during R/V Polarstern cruise ARK-VII/3a from the Hovgaard Ridge (Fram Strait), we found evidence for very deep (>1200 m) iceberg scouring. Five elongated seafloor features have been detected that are interpreted to be iceberg scours. The scours are oriented in north-south/south-north direction and are about 15 m deep, 300 m wide, and 4 km long crossing the entire width of the ridge. They are attributed to multiple giant paleo-icebergs that most probably left the Arctic Ocean southward through Fram Strait. The huge keel depths are indicative of ice sheets extending into the Arctic Ocean being at least 1200 m thick at the calving front during glacial maxima. The deep St. Anna Trough or grounded ice observed at the East Siberian Continental Margin are likely source regions of these icebergs that delivered freshwater to the Nordic Seas.

  7. Taxonomic revision of deep-sea Ostracoda from the Arctic Ocean

    Science.gov (United States)

    Yasuhara, Moriaki; Stepanova, Anna; Okahashi, Hisayo; Cronin, Thomas M.; Brouwers, Elisabeth M.

    2015-01-01

    Taxonomic revision of deep-sea Ostracoda from the Arctic Ocean was conducted to reduce taxonomic uncertainty that will improve our understanding of species ecology, biogeography and relationship to faunas from other deep-sea regions. Fifteen genera and 40 species were examined and (re-)illustrated with high-resolution scanning electron microscopy images, covering most of known deep-sea species in the central Arctic Ocean. Seven new species are described: Bythoceratina lomonosovensis n. sp., Cytheropteron parahamatum n. sp., Cytheropteron lanceae n. sp.,Cytheropteron irizukii n. sp., Pedicythere arctica n. sp., Cluthiawhatleyi n. sp., Krithe hunti n. sp. This study provides a robust taxonomic baseline for application to paleoceanographical reconstruction and biodiversity analyses in this climatically sensitive region.

  8. A double-halocline structure in the Canada Basin of the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    SHI Jiuxin; ZHAO Jinping; LI Shujiang; CAO Yong; QU Ping

    2005-01-01

    A year-round halocline is a particular hydrographic structure in the upper Arctic Ocean. On the basis of an analysis of the hydrographic data collected in the Arctic Ocean, it is found that a double-halocline structure exists in the upper layer of the southern Canada Basin,which is absolutely different from the Cold Halocline Layer (CHL) in the Eurasian Basin. The Pacific-origin water is the primary factor in the formation of the double-halocline structure. The upper halocline lies between the summer modification and the winter modification of the Pacific-origin water while the lower halocline results from the Pacific-origin water overlying upon the Atlantic-origin water. Both haloclines are all the year-round although seasonal and interannual variations have been detected in the historical data.

  9. Results of recent Pacific-Arctic ice-ocean modeling studies at the Naval Postgraduate School

    Institute of Scientific and Technical Information of China (English)

    Jaclyn Clement Kinney; Wieslaw Maslowski

    2008-01-01

    Summary of results from a high - resolution pan - Arctic ice -'ocean model are presented for the northern North Pacific, Bering, Chukchi, and Beaufort seas.The main focus is on the mean circulation, communication from the Gulf of Alaska across the Bering Sea into the western Arctic Ocean and on mesoscale eddy activity within several important ecosystems. Model results from 1979 -2004 are compared to observations whenever possible. The high spatial model resolution at 1/12o (or~9 -km) in the horizontal and 45 levels in the vertical direction allows for representation of eddies with diameters as small as 36 km. However, we believe that upcoming new model integrations at even higher resolution will allow us to resolve even smaller eddies. This is especially important at the highest latitudes where the Rossby radius of deformation is as small as 10 km or less.

  10. Disparate acidification and calcium carbonate desaturation of deep and shallow waters of the Arctic Ocean

    Science.gov (United States)

    Luo, Yiming; Boudreau, Bernard P.; Mucci, Alfonso

    2016-09-01

    The Arctic Ocean is acidifying from absorption of man-made CO2. Current predictive models of that acidification focus on surface waters, and their results argue that deep waters will acidify by downward penetration from the surface. Here we show, with an alternative model, the rapid, near simultaneous, acidification of both surface and deep waters, a prediction supported by current, but limited, saturation data. Whereas Arctic surface water responds directly by atmospheric CO2 uptake, deeper waters will be influenced strongly by intrusion of mid-depth, pre-acidified, Atlantic Ocean water. With unabated CO2 emissions, surface waters will become undersaturated with respect to aragonite by 2105 AD and could remain so for ~600 years. In deep waters, the aragonite saturation horizon will rise, reaching the base of the surface mixed layer by 2140 AD and likely remaining there for over a millennium. The survival of aragonite-secreting organisms is consequently threatened on long timescales.

  11. The relationship between double-diffusive intrusions and staircases in the Arctic Ocean

    Science.gov (United States)

    Bebieva, Yana; Timmermans, Mary-Louise

    2016-11-01

    The origin of double-diffusive staircases in the Arctic Ocean is investigated for the particular background setting in which both temperature and salinity increase with depth. Motivated by observations that show the co-existence of thermohaline intrusions and double-diffusive staircases, a linear stability analysis is performed on the governing equations to determine the conditions under which staircases form. It is shown that a double-diffusive staircase can result from interleaving motions if the observed bulk vertical density ratio is below a critical vertical density ratio estimated for particular lateral and vertical background temperature and salinity gradients. Vertical temperature and salinity gradients dominate over horizontal gradients in determining whether staircases form. Examination of Arctic Ocean temperature and salinity measurements indicates that observations are consistent with the theory for reasonable choices of eddy diffusivity and viscosity.

  12. Disparate acidification and calcium carbonate desaturation of deep and shallow waters of the Arctic Ocean

    Science.gov (United States)

    Luo, Yiming; Boudreau, Bernard P.; Mucci, Alfonso

    2016-01-01

    The Arctic Ocean is acidifying from absorption of man-made CO2. Current predictive models of that acidification focus on surface waters, and their results argue that deep waters will acidify by downward penetration from the surface. Here we show, with an alternative model, the rapid, near simultaneous, acidification of both surface and deep waters, a prediction supported by current, but limited, saturation data. Whereas Arctic surface water responds directly by atmospheric CO2 uptake, deeper waters will be influenced strongly by intrusion of mid-depth, pre-acidified, Atlantic Ocean water. With unabated CO2 emissions, surface waters will become undersaturated with respect to aragonite by 2105 AD and could remain so for ∼600 years. In deep waters, the aragonite saturation horizon will rise, reaching the base of the surface mixed layer by 2140 AD and likely remaining there for over a millennium. The survival of aragonite-secreting organisms is consequently threatened on long timescales. PMID:27659188

  13. The Arctic Summer Cloud-Ocean Study (ASCOS: overview and experimental design

    Directory of Open Access Journals (Sweden)

    M. Tjernström

    2013-05-01

    Full Text Available The climate in the Arctic is changing faster than anywhere else on Earth. Poorly understood feedback processes relating to Arctic clouds and aerosol-cloud interactions contribute to a poor understanding of the present changes in the Arctic climate system, and also to a large spread in projections of future climate in the Arctic. The problem is exacerbated by the paucity of research-quality observations in the central Arctic. Improved formulations in climate models require such observations, which can only come from measurements in-situ in this difficult to reach region with logistically demanding environmental conditions. The Arctic Summer Cloud-Ocean Study (ASCOS was the most extensive central Arctic Ocean expedition with an atmospheric focus during the International Polar Year (IPY 2007–2008. ASCOS focused on the study of the formation and life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on Svalbard on 2 August and returned on 9 September 2008. In transit into and out of the pack ice, four short research stations were undertaken in the Fram Strait; two in open water and two in the marginal ice zone. After traversing the pack-ice northward an ice camp was set up on 12 August at 87°21' N 01°29' W and remained in operation through 1 September, drifting with the ice. During this time extensive measurements were taken of atmospheric gas and particle chemistry and physics, mesoscale and boundary-layer meteorology, marine biology and chemistry, and upper ocean physics. ASCOS provides a unique interdisciplinary data set for development and testing of new hypotheses on cloud processes, their interactions with the sea ice and ocean and associated physical, chemical, and biological processes and interactions. For example, the first ever quantitative observation of bubbles in Arctic leads, combined with the unique discovery of marine organic material, polymer gels with an origin in the ocean, inside cloud droplets suggest the

  14. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations: Hydrography and fluxes

    Science.gov (United States)

    Ilicak, Mehmet; Drange, Helge

    2016-04-01

    We compare the simulated Arctic Ocean in fifteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II). Most of these models are the ocean and sea-ice components of the coupled climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments. We mainly focus on the hydrography of the Arctic interior, the state of Atlantic Water layer and heat and volume transports at the gateways of the Davis Strait, the Bering Strait, the Fram Strait and the Barents Sea Opening. We found that there is a large spread in temperature in the Arctic Ocean between the models, and generally large differences compared to the observed temperature at intermediate depths. Warm bias models have a strong temperature anomaly of inflow of the Atlantic Water entering the Arctic Ocean through the Fram Strait. Another process that is not represented accurately in the CORE-II models is the formation of cold and dense water, originating on the eastern shelves. In the cold bias models, excessive cold water forms in the Barents Sea and spreads into the Arctic Ocean through the St. Anna Through. There is a large spread in the simulated mean heat and volume transports through the Fram Strait and the Barents Sea Opening. The models agree more on the decadal variability, to a large degree dictated by the common atmospheric forcing. We conclude that the CORE-II model study helps us to understand the crucial biases in the Arctic Ocean. The current coarse resolution state-of-the-art ocean models need to be improved in accurate representation of the Atlantic Water inflow into the Arctic and density currents coming from the shelves.

  15. Toward Improved Estimation of the Dynamic Topography and Ocean Circulation in the High Latitude and Arctic Ocean: The Importance of GOCE

    DEFF Research Database (Denmark)

    Johannessen, J. A.; Raj, R. P.; Nilsen, J. E. Ø.

    2014-01-01

    and sea ice thickness influencing the albedo and CO2 exchange, melting of the Greenland Ice Sheet and increased thawing of surrounding permafrost regions. In turn, the hydrological cycle in the high latitude and Arctic is expected to undergo changes although to date it is challenging to accurately......The Arctic plays a fundamental role in the climate system and shows significant sensitivity to anthropogenic climate forcing and the ongoing climate change. Accelerated changes in the Arctic are already observed, including elevated air and ocean temperatures, declines of the summer sea ice extent...... circulation and transport variability in the high latitude and Arctic Ocean. In this respect, this study combines in situ hydrographical data, surface drifter data and direct current meter measurements, with coupled sea ice–ocean models, radar altimeter data and the latest GOCE-based geoid in order...

  16. Profile data from CTD casts aboard the F/V Ocean Explorer in the Arctic Ocean and Beaufort Sea from 2008-08-06 to 2008-08-22 (NODC Accession 0001920)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This profile data aboard the F/V Ocean Explorer in the Arctic Ocean and Beaufort Sea from August 6, 2008 to August 22, 2008 was supported by the Minerals Management...

  17. Atmospheric nitrous oxide observations above the oceanic surface during the first Chinese Arctic Research Expedition

    Institute of Scientific and Technical Information of China (English)

    朱仁斌; 孙立广; 谢周清; 赵俊琳

    2003-01-01

    339 gas samples above oceanic surface were collected on the cruise of "Xuelong" expeditionary ship and nitrous oxide concentrations were analyzed in the laboratory. Results showed that Atmospheric average N20 concentration was 309 ± 3.8nL/L above the surface of northern Pacific and Arctic ocean. N2O concentrations were significantly different on the northbound and southbound track in the range of the same latitude, 308.0 ± 3.5 nL/L from Shanghai harbor to the Arctic and 311.9 ± 2.5 nL/L from the Arctic to Shanghai harbor. N2O concentration had a greater changing magnitude on the mid- and high-latitude oceanic surface of northern Pacific Ocean than in the other latitudinal ranges. The correlation between the concentrations of the compositions in the aerosol samples and atmospheric N2O showed that continental sources had a great contribution on atmospheric N2 O concentration above the oceanic surface. Atmospheric N2O concentration significantly increased when the expeditionary ship approached Shanghai harbor. The average N2O concentrations were 315.1 ±2.5 nL/L, 307.2 ±1.4 nL/L and 306.2 ±0.7 nL/L, respectively, at Shanghai harbor, at ice stations and at floating ices. The distribution of N2O concentrations was related with air pressure and temperature above the mid- and high-latitude Pacific Ocean.

  18. TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

    Directory of Open Access Journals (Sweden)

    P. Sakov

    2012-04-01

    Full Text Available We present a detailed description of TOPAZ4, the latest version of TOPAZ – a coupled ocean-sea ice data assimilation system for the North Atlantic Ocean and Arctic. It is the only operational, large-scale ocean data assimilation system that uses the ensemble Kalman filter. This means that TOPAZ features a time-evolving, state-dependent estimate of the state error covariance. Based on results from the pilot MyOcean reanalysis for 2003–2008, we demonstrate that TOPAZ4 produces a realistic estimate of the ocean circulation and the sea ice. We find that the ensemble spread for temperature and sea-level remains fairly constant throughout the reanalysis demonstrating that the data assimilation system is robust to ensemble collapse. Moreover, the ensemble spread for ice concentration is well correlated with the actual errors. This indicates that the ensemble statistics provide reliable state-dependent error estimates – a feature that is unique to ensemble-based data assimilation systems. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when in situ profiles below the ice in the Arctic Ocean are assimilated. We find that data assimilation improves the match to independent observations compared to a free model. Improvements are particularly noticeable for ice thickness, salinity in the Arctic, and temperature in the Fram Strait, but not for transport estimates or underwater temperature. At the same time, the pilot reanalysis has revealed several flaws in the system that have degraded its performance. Finally, we show that a simple bias estimation scheme can effectively detect the seasonal or constant bias in temperature and sea-level.

  19. Seasonal Changes in the Marine Production Cycles in Response to Changes in Arctic Sea Ice and Upper Ocean Circulation

    Science.gov (United States)

    Spitz, Y. H.; Ashjian, C. J.; Campbell, R. G.; Steele, M.; Zhang, J.

    2011-12-01

    Significant seasonal changes in arctic sea ice have been observed in recent years, characterized by unprecedented summer melt-back. As summer sea ice extent shrinks to record low levels, the peripheral seas of the Arctic Ocean are exposed much earlier to atmospheric surface heat flux, resulting in longer and warmer summers with more oceanic heat absorption. The changing seasonality in the arctic ice/ocean system will alter the timing, magnitude, duration, and pattern of marine production cycles by disrupting key trophic linkages and feedbacks in planktonic food webs. We are using a coupled pan-arctic Biology/Ice/Ocean Modeling and Assimilation System (BIOMAS) to investigate the changes in the patterns of seasonality in the arctic physical and biological system. Focus on specific regions of the Arctic, such as the Chukchi Sea, the Beaufort Sea and the adjacent central Arctic, reveals that changes in the timing of the spring bloom, its duration and the response of the secondary producers vary regionally. The major changes are, however, characterized by an earlier phytoplankton bloom and a slight increase of the biomass. In addition, the largest response in the secondary producers is seen in the magnitude of the microzooplankton concentration as well as in the period (early summer to late fall) over which the microzooplankton is present.

  20. Heat flow measurements on the Lomonosov Ridge, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    XIAO Wentao; ZHANG Tao; ZHENG Yulong; GAO Jinyao

    2013-01-01

    Heat flow was measured on the Lomonosov Ridge during the 5th Chinese National Arctic Expedition in 2012. To derive the time-temperature curve, resistivity data were transformed to temperature by the resistivity-temperature program. Direct reading and linear regression methods were used to calculate the equilibrium temperature, which were regressed against the depth of the probes in sediment to derive the geothermal gradient. Then, heat flow was calculated as the product of geothermal gradient and thermal conductivity of sediments. The heat flow values on the basis of the two methods were similar (i.e., 67.27 mW/m2 and 63.99 mW/m2, respectively). The results are consistent with the measurements carried out at adjacent sites. The age of the Lomonosov Ridge predicted by the heat flow-age model was 62 Ma, which is in accordance with the inference that the ridge was separated from Eurasia at about 60 Ma.

  1. Quantifying Methane Emissions from the Arctic Ocean Seabed to the Atmosphere

    Science.gov (United States)

    Platt, Stephen; Pisso, Ignacio; Schmidbauer, Norbert; Hermansen, Ove; Silyakova, Anna; Ferré, Benedicte; Vadakkepuliyambatta, Sunil; Myhre, Gunnar; Mienert, Jürgen; Stohl, Andreas; Myhre, Cathrine Lund

    2016-04-01

    Large quantities of methane are stored under the seafloor in the shallow waters of the Arctic Ocean. Some of this is in the form of hydrates which may be vulnerable to deomposition due to surface warming. The Methane Emissions from Arctic Ocean to Atmosphere MOCA, (http://moca.nilu.no/) project was established in collaboration with the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE, https://cage.uit.no/). In summer 2014, and summer and autumn 2015 we deployed oceanographic CTD (Conductivity, Temperature, Depth) stations and performed state-of-the-art atmospheric measurements of CH4, CO2, CO, and other meteorological parameters aboard the research vessel Helmer Hanssen west of Prins Karl's Forland, Svalbard. Air samples were collected for isotopic analysis (13C, 2H) and quantification of other hydrocarbons (ethane, propane, etc.). Atmospheric measurements are also available from the nearby Zeppelin Observatory at a mountain close to Ny-Ålesund, Svalbard. We will present data from these measurements that show an upper constraint of the methane flux in measurement area in 2014 too low to influence the annual CH4 budget. This is further supported by top-down constraints (maximum release consistent with observations at the Helmer Hansen and Zeppelin Observatory) determined using FLEXPART foot print sensitivities and the OsloCTM3 model. The low flux estimates despite the presence of active seeps in the area (numerous gas flares were observed using echo sounding) were apparently due to the presence of a stable ocean pycnocline at ~50 m.

  2. Mid-Cenozoic tectonic and paleoenvironmental setting of the central Arctic Ocean

    Science.gov (United States)

    O'Regan, M.; Moran, K.; Backman, J.; Jakobsson, M.; Sangiorgi, F.; Brinkhuis, Henk; Pockalny, Rob; Skelton, Alasdair; Stickley, Catherine E.; Koc, N.; Brumsack, Hans-Juergen; Willard, Debra A.

    2008-01-01

    Drilling results from the Integrated Ocean Drilling Program's Arctic Coring Expedition (ACEX) to the Lomonosov Ridge (LR) document a 26 million year hiatus that separates freshwater-influenced biosilica-rich deposits of the middle Eocene from fossil-poor glaciomarine silty clays of the early Miocene. Detailed micropaleontological and sedimentological data from sediments surrounding this mid-Cenozoic hiatus describe a shallow water setting for the LR, a finding that conflicts with predrilling seismic predictions and an initial postcruise assessment of its subsidence history that assumed smooth thermally controlled subsidence following rifting. A review of Cenozoic tectonic processes affecting the geodynamic evolution of the central Arctic Ocean highlights a prolonged phase of basin-wide compression that ended in the early Miocene. The coincidence in timing between the end of compression and the start of rapid early Miocene subsidence provides a compelling link between these observations and similarly accounts for the shallow water setting that persisted more than 30 million years after rifting ended. However, for much of the late Paleogene and early Neogene, tectonic reconstructions of the Arctic Ocean describe a landlocked basin, adding additional uncertainty to reconstructions of paleodepth estimates as the magnitude of regional sea level variations remains unknown.

  3. Observational estimation of heat budgets on drifting ice and open water over the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Estimates of the surface heat budget over drifting ice and open water in the Arctic Ocean are made using eddy correlation and flux-profile methods using data obtained from drifting ice and from the R/V Xuelong in the Chinese National Arctic Research Expedition during August 19-24,1999. The results show that the net radiation received by the ice surface is mainly lost through the sensible heat flux and the heat flux due to melting ice, and the latent heat flux making small contribution to the heat balance. However, the heat balance of the open water surface was dominated by the radiative flux whereas the latent and sensible heat fluxes and the oceanic heat flux were greater than those on the sea-ice surface. These results emphasize that thermodynamic processes are quite different between air/open water and air/sea-ice over the Arctic Ocean which is important when considering the effect of sea-air-ice interaction on climate change process during the summer period.

  4. Modeling the seasonal variability of a coupled Arctic ice-ocean system

    Science.gov (United States)

    Hakkinen, Sirpa; Mellor, George L.

    1992-01-01

    The seasonal variability of the ice-ocean system in the Arctic Basin and the Norwegian, Greenland, and Barents Seas was modeled using a three-dimensional coupled ice-ocean model developed at Princeton University. The snow-ice model uses a three-level thermodynamic scheme similar to Semtner's (1976), but is extended to include the effect of leads. It is shown that simulations using the climatological monthly forcing fields produce a realistic seasonal variability of the ice cover. The ice thickness had a considerable sensitivity to the choice of the long-wave back radiation scheme, but these effects can be reduced through dynamical factors.

  5. Projected Impact of Climate Change on the Water and Salt Budgets of the Arctic Ocean by a Global Climate Model

    Science.gov (United States)

    Miller, James R.; Russell, Gary L.

    1996-01-01

    The annual flux of freshwater into the Arctic Ocean by the atmosphere and rivers is balanced by the export of sea ice and oceanic freshwater. Two 150-year simulations of a global climate model are used to examine how this balance might change if atmospheric greenhouse gases (GHGs) increase. Relative to the control, the last 50-year period of the GHG experiment indicates that the total inflow of water from the atmosphere and rivers increases by 10% primarily due to an increase in river discharge, the annual sea-ice export decreases by about half, the oceanic liquid water export increases, salinity decreases, sea-ice cover decreases, and the total mass and sea-surface height of the Arctic Ocean increase. The closed, compact, and multi-phased nature of the hydrologic cycle in the Arctic Ocean makes it an ideal test of water budgets that could be included in model intercomparisons.

  6. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    Science.gov (United States)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p  0.95, p oceans.

  7. Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

    DEFF Research Database (Denmark)

    Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V.

    2014-01-01

    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are re......The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid...

  8. Persistent export of 231Pa from the deep central Arctic Ocean over the past 35,000 years.

    Science.gov (United States)

    Hoffmann, Sharon S; McManus, Jerry F; Curry, William B; Brown-Leger, L Susan

    2013-05-30

    The Arctic Ocean has an important role in Earth's climate, both through surface processes such as sea-ice formation and transport, and through the production and export of waters at depth that contribute to the global thermohaline circulation. Deciphering the deep Arctic Ocean's palaeo-oceanographic history is a crucial part of understanding its role in climatic change. Here we show that sedimentary ratios of the radionuclides thorium-230 ((230)Th) and protactinium-231 ((231)Pa), which are produced in sea water and removed by particle scavenging on timescales of decades to centuries, respectively, record consistent evidence for the export of (231)Pa from the deep Arctic and may indicate continuous deep-water exchange between the Arctic and Atlantic oceans throughout the past 35,000 years. Seven well-dated box-core records provide a comprehensive overview of (231)Pa and (230)Th burial in Arctic sediments during glacial, deglacial and interglacial conditions. Sedimentary (231)Pa/(230)Th ratios decrease nearly linearly with increasing water depth above the core sites, indicating efficient particle scavenging in the upper water column and greater influence of removal by lateral transport at depth. Although the measured (230)Th burial is in balance with its production in Arctic sea water, integrated depth profiles for all time intervals reveal a deficit in (231)Pa burial that can be balanced only by lateral export in the water column. Because no enhanced sink for (231)Pa has yet been found in the Arctic, our records suggest that deep-water exchange through the Fram strait may export (231)Pa. Such export may have continued for the past 35,000 years, suggesting a century-scale replacement time for deep waters in the Arctic Ocean since the most recent glaciation and a persistent contribution of Arctic waters to the global ocean circulation.

  9. Ship-borne Observations of Atmospheric Black Carbon Aerosol Particles over the Arctic Ocean, Bering Sea, and North Pacific Ocean during September 2014

    Science.gov (United States)

    Taketani, F.; Miyakawa, T.; Takashima, H.; Komazaki, Y.; Kanaya, Y.; PAN, X.; Inoue, J.

    2015-12-01

    Measurements of refractory black carbon (rBC) aerosol particles using a highly sensitive online single particle soot photometer were performed on-board the R/V Mirai during a cruise across the Arctic Ocean, Bering Sea, and the North Pacific Ocean (31 August-9 October 2014). The measured rBC mass concentrations over the Arctic Ocean in the latitudinal region > 70°N were in the range 0-66 ng/m3 for 1-min averages, with an overall mean value of 1.0 ± 1.2 ng/m3. Single-particle-based observations enabled the measurement of such low rBC mass concentrations. The effects of long-range transport from continents to the Arctic Ocean were limited during the observed period, suggesting that such low rBC concentration levels would prevail over the Arctic Ocean. An analysis of rBC mixing states showed that particles with a non-shell/core structure made a significant contribution to the rBC particles detected over the Arctic Ocean.

  10. Shipborne observations of atmospheric black carbon aerosol particles over the Arctic Ocean, Bering Sea, and North Pacific Ocean during September 2014

    Science.gov (United States)

    Taketani, Fumikazu; Miyakawa, Takuma; Takashima, Hisahiro; Komazaki, Yuichi; Pan, Xiaole; Kanaya, Yugo; Inoue, Jun

    2016-02-01

    Measurements of refractory black carbon (rBC) aerosol particles using a highly sensitive online single particle soot photometer were performed on board the R/V Mirai during a cruise across the Arctic Ocean, Bering Sea, and North Pacific Ocean (31 August to 9 October 2014). The measured rBC mass concentrations over the Arctic Ocean in the latitudinal region > 70°N were in the range 0-66 ng/m3 for 1 min averages, with an overall mean value of 1.0 ± 1.2 ng/m3. Single-particle-based observations enabled the measurement of such low rBC mass concentrations. The effects of long-range transport from continents to the Arctic Ocean were limited during the observed period, which suggests that the low rBC concentration levels would prevail over the Arctic Ocean. An analysis of rBC mixing states showed that particles with a nonshell/noncore structure made a significant contribution to the rBC particles detected over the Arctic Ocean.

  11. Controlling factors analysis of pCO2 distribution in the Western Arctic Ocean in summertime

    Science.gov (United States)

    Song, Xuelian; Bai, Yan; Hao, Zengzhou; Zhun, Qiankun; Chen, Jianyu; Gong, Fang

    2015-10-01

    The uptake of carbon dioxide (CO2) by the Arctic Ocean has been changing because of the rapid sea-ice retreat with global warming. The Chukchi Sea is the only gateway of the warm and nutrient-rich Pacific Ocean water flowing into the North Pole, and the high productivity-water had great impact on the CO2 uptake by the Arctic Ocean. We used the in situ underway data of aquatic partial pressure of CO2 (pCO2), temperature and salinity, as well as the remote sensing data of sea ice concentration, chlorophyll concentration, sea surface temperature in August in 2008, 2011 and 2012 to analyze the major controlling factors of aquatic pCO2 in the Western Arctic Ocean. We analyzed the pCO2 variation under the effects of thermodynamic process (temperature), mixing of water mass (salinity), biological drawdown (chlorophyll), and sea ice concentration. The aquatic pCO2 was generally unsaturation relative to the atmospheric CO2 in most of the Western Arctic Ocean. According to different controlling mechanisms, the study area was divided into three parts: the area affected by the Pacific Ocean water (mainly in the Chukchi Sea), the area where sea ice mostly melted with weak biological production (the southern Canada Basin and the Western Beaufort Sea), and the area mostly covered by sea ice (the Northern Canada Basin). The aquatic pCO2 was low in the Chukchi Sea with the influence of the Pacific Ocean water. While, pCO2 in the area where sea ice melted was up to 360-380 μatm because of warming, CO2 invasion from the atmosphere, and a low biological production. For the Canada Basin, it was controlled by temperature change and sea ice cover. The remote sensing data in large spatial-temporal scale can help to understand the pCO2 variation and its response to global change; and it needs to develop satellite algorithm of pCO2 based on the quantification of controlling processes.

  12. Arctic Ocean freshwater composition, pathways and transformations from a passive tracer simulation

    Directory of Open Access Journals (Sweden)

    Per Pemberton

    2014-07-01

    Full Text Available Freshwater (FW induced transformations in the upper Arctic Ocean were studied using a coupled regional sea ice-ocean model driven by winds and thermodynamic forcing from a reanalysis of data during the period 1948–2011, focusing on the mean state during 1968–2011. Using passive tracers to mark a number of FW sources and sinks, their mean composition, pathways and export were examined. The distribution of the simulated FW height reproduced the known features of the Arctic Ocean and volume-integrated FW content matched climatological estimates reasonably well. Input from Eurasian rivers and extraction by sea-ice formation dominate the composition of the Arctic FW content whilst Pacific water increases in importance in the Canadian Basin. Though pathways generally agreed with previous studies the locus of the Eurasian runoff shelf-basin transport centred at the Alpha-Mendeleyev ridge, shifting the Pacific–Atlantic front eastwards. A strong coupling between tracers representing Eurasian runoff and sea-ice formation showed how water modified on the shelf spreads across the Arctic and mainly exits through the Fram Strait. Transformation to salinity dependent coordinates showed how Atlantic water is modified by both low-salinity shelf and Pacific waters in an estuary-like overturning producing water masses of intermediate salinity that are exported to the Nordic Seas. A total halocline renewal rate of 1.0 Sv, including both shelf-basin exchange and cross-isohaline flux, was estimated from the transports: both components were of equal magnitude. The model's halocline shelf-basin exchange is dominated by runoff and sea-ice processes at the western shelves (the Barents and Kara seas and Pacific water at the eastern shelves (the Laptev, East Siberian and Chukchi seas.

  13. Late Quaternary stratigraphy and sedimentation patterns in the western Arctic Ocean

    Science.gov (United States)

    Polyak, L.; Bischof, J.; Ortiz, J.D.; Darby, D.A.; Channell, J.E.T.; Xuan, C.; Kaufman, D.S.; Lovlie, R.; Schneider, D.A.; Eberl, D.D.; Adler, R.E.; Council, E.A.

    2009-01-01

    Sediment cores from the western Arctic Ocean obtained on the 2005 HOTRAX and some earlier expeditions have been analyzed to develop a stratigraphic correlation from the Alaskan Chukchi margin to the Northwind and Mendeleev-Alpha ridges. The correlation was primarily based on terrigenous sediment composition that is not affected by diagenetic processes as strongly as the biogenic component, and paleomagnetic inclination records. Chronostratigraphic control was provided by 14C dating and amino-acid racemization ages, as well as correlation to earlier established Arctic Ocean stratigraphies. Distribution of sedimentary units across the western Arctic indicates that sedimentation rates decrease from tens of centimeters per kyr on the Alaskan margin to a few centimeters on the southern ends of Northwind and Mendeleev ridges and just a few millimeters on the ridges in the interior of the Amerasia basin. This sedimentation pattern suggests that Late Quaternary sediment transport and deposition, except for turbidites at the basin bottom, were generally controlled by ice concentration (and thus melt-out rate) and transportation distance from sources, with local variances related to subsurface currents. In the long term, most sediment was probably delivered to the core sites by icebergs during glacial periods, with a significant contribution from sea ice. During glacial maxima very fine-grained sediment was deposited with sedimentation rates greatly reduced away from the margins to a hiatus of several kyr duration as shown for the Last Glacial Maximum. This sedimentary environment was possibly related to a very solid ice cover and reduced melt-out over a large part of the western Arctic Ocean.

  14. The composition and origination of particles from surface water in the Chukchi Sea, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    YU Xiaoguo; LEI Jijiang; YAO Xuying; ZHU Jihao; JIN Xiaobing

    2014-01-01

    Suspended particle samples were collected at 11 stations on the shelf and slope regions of the Chukchi Sea and the central Arctic Ocean during the fifth Chinese National Arctic Research Expedition (summer 2012). The particle concentration, total organic carbon (TOC), total nitrogen (TN) and the isotopic composition of the samples were analyzed. The suspended particle concentration varied between 0.56 and 4.01 mg.L-1;the samples collected from the sea ice margin have higher concentrations. The organic matter content is higher in the shelf area (TOC:9.78%-20.24%;TN:0.91%-2.31%), and exhibits heavier isotopic compositions (δ13C: -23.29‰ to -26.33‰ PDB;δ15N: 6.14‰-7.78‰), indicating that the organic matter is mostly marine in origin with some terrigenous input. In the slope and the central Arctic Ocean, the organic matter content is lower (TOC:8.06%-8.96%;TN:0.46%-0.72%), except for one sample (SR15), and has lighter isotopic compositions (δ13C:-26.93‰to-27.78‰PDB;δ15N:4.13‰-4.84‰). This indicates that the organic matter is mostly terrestrially-derived in these regions. The extremely high amount of terrigenous organic matter (TOC:27.94%;TN:1.16%;δ13C:-27.43‰PDB;δ15N:3.81‰) implies that it was carried by transpolar currents from the East Siberian Sea. Material, including sea ice algae, carried by sea ice are the primary source for particles in the sea ice margins. Sea ice melting released a substantial amount of biomass into the shelf, but a large amount of detrital and clay minerals in the slope and the central Arctic Ocean.

  15. Temperature, salinity, conductivity, and other measurements collected in the Northern Ocean as part of the Arctic Experiment in 1994 (NODC Accession 0002728)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Investigation of thermohaline circulation in Nordic Seas, hydrography and pathways of Atlantic water summer Arctic experiments

  16. Meteorological, oceanographic, and buoy data from JAMSTEC from five drifting buoys, named J-CAD (JAMSTEC Compact Arctic Drifter) in the Arctic Ocean from 2000 to 2003 (NODC Accession 0002201)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 1999, JAMSTEC and MetOcean Data System Ltd. developed a new drifting buoy, named J-CAD (JAMSTEC Compact Arctic Drifter), to conduct long-term observations in the...

  17. Remote Sensing of Ocean Color in the High Arctic

    Science.gov (United States)

    Cota, G. F.; Platt, T.; Harrison, W. G.

    1997-01-01

    With four years of NASA SeaWiFS funding I established a completely new capability and expertise for in-water optical measurements nearly from scratch and with very little optical background. My first-year budget included only capital for a profiling spectral radiometer. Over the next 30 months we conducted six cruises and collected almost 300 optical profiles in challenging environments; many were collected from 21' launches. I also changed institutions during this period: it is very disruptive to move, set up a new lab, and hire and train new people, etc. We also did not have access to NASA funds for almost a year during the move because of difficulties in subcontracting and/or transferring funds. Nevertheless, we delivered data sets from six bio-optical cruises from three high latitude regions, although only two or three cruises from two areas were promised for our SeaWiFS research. The three Canadian Arctic field programs comprise the most comprehensive high latitude bio-optical and biogeochemical data sets in existence. Optical and pigment data from all six cruises have been submitted to NASA and are being included in the algorithm development test set. Additional data are still being submitted.

  18. Geochemistry of clathrate-derived methane in Arctic Ocean waters

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, S.M.; Reagan, M.T.; Moridis, G.J.; Cameron-Smith, P.J.

    2010-03-15

    Alterations to the composition of seawater are estimated for microbial oxidation of methane from large polar clathrate destabilizations, which may arise in the coming century. Gas fluxes are taken from porous flow models of warming Arctic sediment. Plume spread parameters are then used to bracket the volume of dilution. Consumption stoichiometries for the marine methanotrophs are based on growth efficiency and elemental/enzyme composition data. The nutritional demand implied by extra CH{sub 4} removal is compared with supply in various high latitude water masses. For emissions sized to fit the shelf break, reaction potential begins at one hundred micromolar and falls to order ten a thousand kilometers downstream. Oxygen loss and carbon dioxide production are sufficient respectively to hypoxify and acidify poorly ventilated basins. Nitrogen and the monooxygenase transition metals may be depleted in some locations as well. Deprivation is implied relative to existing ecosystems, along with dispersal of the excess dissolved gas. Physical uncertainties are inherent in the clathrate abundance, patch size, outflow buoyancy and mixing rate. Microbial ecology is even less defined but may involve nutrient recycling and anaerobic oxidizers.

  19. Bacterial production and microbial food web structure in a large arctic river and the coastal Arctic Ocean

    Science.gov (United States)

    Vallières, Catherine; Retamal, Leira; Ramlal, Patricia; Osburn, Christopher L.; Vincent, Warwick F.

    2008-12-01

    Globally significant quantities of organic carbon are stored in northern permafrost soils, but little is known about how this carbon is processed by microbial communities once it enters rivers and is transported to the coastal Arctic Ocean. As part of the Arctic River-Delta Experiment (ARDEX), we measured environmental and microbiological variables along a 300 km transect in the Mackenzie River and coastal Beaufort Sea, in July-August 2004. Surface bacterial concentrations averaged 6.7 × 10 5 cells mL - 1 with no significant differences between sampling zones. Picocyanobacteria were abundant in the river, and mostly observed as cell colonies. Their concentrations in the surface waters decreased across the salinity gradient, dropping from 51,000 (river) to 30 (sea) cells mL - 1 . There were accompanying shifts in protist community structure, from diatoms, cryptophytes, heterotrophic protists and chrysophytes in the river, to dinoflagellates, prymnesiophytes, chrysophytes, prasinophytes, diatoms and heterotrophic protists in the Beaufort Sea. Size-fractionated bacterial production, as measured by 3H-leucine uptake, varied from 76 to 416 ng C L - 1 h - 1 . The contribution of particle-attached bacteria (> 3 µm fraction) to total bacterial production decreased from > 90% at the Mackenzie River stations to importance of this particle-based fraction was inversely correlated with salinity and positively correlated with particulate organic carbon concentrations. Glucose enrichment experiments indicated that bacterial metabolism was carbon limited in the Mackenzie River but not in the coastal ocean. Prior exposure of water samples to full sunlight increased the biolability of dissolved organic carbon (DOC) in the Mackenzie River but decreased it in the Beaufort Sea. Estimated depth-integrated bacterial respiration rates in the Mackenzie River were higher than depth-integrated primary production rates, while at the marine stations bacterial respiration rates were near or

  20. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  1. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mar Fernández-Méndez

    2016-11-01

    Full Text Available The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing towards a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77ºN. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  2. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Buttigieg, Pier L.; Rapp, Josephine Z.; Krumpen, Thomas; Zehr, Jonathan P.; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed. PMID:27933047

  3. October Cloud Increases Over the Arctic Ocean as Observed by MISR and CALIPSO

    Science.gov (United States)

    Wu, Dong L.; Lee, Jae N.

    2011-01-01

    The Beaufort and East Siberian Sea (BESS) shows a large increase in surface air temperature (SAT) in the recent decade for months of Sep-Nov, and NASA's Terra satellite have provided valuable measurements for this important decade of the intensified Arctic warming. In particular, MISR data since 2000 and CALIPSO cloud measurements since 2006 reveal a significant increase of low cloud cover in October, which is largest in the daylight Arctic months (March-October). Causes of the warming remain unclear; but increased absorption of summer solar radiation and autumn low cloud formation have been suggested as a positive ice-temperature-cloud feedback in the Arctic. The observed increase of low cloud cover supports the theorized positive ice-temperature-cloud feedback, whereby more open water in the Arctic Ocean increases summer absorption of solar radiation, and subsequent evaporation, which leads to more low clouds in autumn. Trapping longwave radiation, these clouds effectively lengthen the melt season and reduce perennial ice pack formation, making sea ice more vulnerable to the next melt season

  4. Lagrangian analysis of sea-ice dynamics in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Sándor Szanyi

    2016-11-01

    Full Text Available In this study, we present Lagrangian diagnostics to quantify changes in the dynamical characteristics of the Arctic sea-ice cover from 2006 to 2014. Examined in particular is the evolution in finite-time Lyapunov exponents (FTLEs, which monitor the rate at which neighbouring particle trajectories diverge, and stretching rates throughout the Arctic. In this analysis, we compute FTLEs for the Arctic ice-drift field using the 62.5 km daily sea-ice motion vector data from the European Organisation for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facility. Results from the FTLE analysis highlight the existence of three distinct dynamical regions with strong stretching, captured by FTLE maxima or ridges. It is further shown that FTLE ridges are dominated by shear, with contributions from divergence in the Beaufort Sea. Localization of FTLE features following the 2012 record minimum in summertime sea-ice extent illustrates the emergence of an Arctic characterized by increased mixing. Results also demonstrate higher FTLEs in years when lower multi-year ice extent is observed.

  5. Vulnerability of polar oceans to anthropogenic acidification: comparison of arctic and antarctic seasonal cycles.

    Science.gov (United States)

    Shadwick, E H; Trull, T W; Thomas, H; Gibson, J A E

    2013-01-01

    Polar oceans are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and Antarctic site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 3°C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 μmol/kg), and lower summer pH (8.15 vs 8.5), than the Antarctic site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline Antarctic system. In addition, the excess surface nutrients in the Antarctic may allow mitigation of acidification, via CO2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation.

  6. The Arctic Ocean in summer: A quasi-synoptic inverse estimate of boundary fluxes and water mass transformation

    OpenAIRE

    Tsubouchi, T; S. Bacon; Garabato, A.C. Naveira; Aksenov, Y.; Laxon, S. W.; Fahrbach, E.; Beszczynska-Möller, A.; Hansen, E.; Lee, Craig M.; Ingvaldsen, Randi

    2012-01-01

    The first quasi-synoptic estimates of Arctic Ocean and sea ice net fluxes of volume, heat and freshwater are calculated by application of an inverse model to data around the ocean boundary. Hydrographic measurements from four gateways to the Arctic (Bering, Davis, and Fram Straits and the Barents Sea Opening) completely enclose the ocean, and were made within the same 32-day period in summer 2005. The inverse model is formulated as a set of full-depth and density-layer-specific volume and sal...

  7. First Recovery of Submarine Basalts from the Chukchi Borderland and Alpha / Mendeleev Ridge, Arctic Ocean

    Science.gov (United States)

    Andronikov, A.; Mukasa, S.; Mayer, L. A.; Brumley, K.

    2008-12-01

    In addition to multibeam bathymetric mapping of the Amerasia Basin in the high Arctic Ocean, the August- September 2008 cruise of USCGC Icebreaker HEALY (HLY0805) conducted a total of seven dredging profiles along the southern sectors of the Alpha/Mendeleev Ridge and in the northernmost region of Northwind Ridge of Chukchi Borderland. Five of the seven dredges were recovered on relatively gentle slopes (30-40°) and yielded mostly mud with a small number of fragments of sedimentary rocks and ice rafted debris (IRD), which indicates either rapid sedimentation rates on the bathymetrically high features sampled or lack of recently active volcanism on these features. Two dredges taken from steep escarpments with slopes (> 55°) at >3.5 km depth recovered some of the first known submarine basaltic samples from the Arctic Ocean floor away from the Gakkel Ridge. Ragged, freshly exposed edges indicate that these samples were broken from outcrop rather than being IRD. In some cases (e.g., a rise on the ocean floor between the Alpha/Mendeleev Ridge and Northwind Ridge) the samples have well-preserved pillow-basalt structures with fresh glassy rims up to 4 cm thick. Inward from the rims, the rocks are dark-grey lavas, some with visible plagioclase laths and rare phenocrysts up to 0.5 mm in length, some with visible signs of alteration such as local occurrence of chlorite. Surfaces that were exposed to water can be covered with a thin black film of Mn oxides. Occurrence of this volcanism away from any obvious spreading centers compels us to hypothesize that forthcoming geochemical analyses are likely to identify these rocks as the first Arctic Ocean floor samples to exhibit ocean island basalt compositions. The dredge taken from the northern slope of Northwind Ridge, along slopes as steep as > 45°, recovered a variety of rock types including sedimentary and basaltic rocks. Some of the basalts have columnar jointing (the size of the columns is only up to 5-6 cm across

  8. Fracture of summer perennial sea ice by ocean swell as a result of Arctic storms

    Science.gov (United States)

    Asplin, Matthew G.; Galley, Ryan; Barber, David G.; Prinsenberg, Simon

    2012-06-01

    The Arctic summer minimum sea ice extent has experienced a decreasing trend since 1979, with an extreme minimum extent of 4.27 × 106 km2 in September 2007, and a similar minimum in 2011. Large expanses of open water in the Siberian, Laptev, Chukchi, and Beaufort Seas result from declining summer sea ice cover, and consequently introduce long fetch within the Arctic Basin. Strong winds from migratory cyclones coupled with increasing fetch generate large waves which can propagate into the pack ice and break it up. On 06 September 2009, we observed the intrusion of large swells into the multiyear pack ice approximately 250 km from the ice edge. These large swells induced nearly instantaneous widespread fracturing of the multiyear pack ice, reducing the large, (>1 km diameter) parent ice floes to small (100-150 m diameter) floes. This process increased the total ice floe perimeter exposed to the open ocean, allowing for more efficient distribution of energy from ocean heat fluxes, and incoming radiation into the floes, thereby enhancing lateral melting. This process of sea ice decay is therefore presented as a potential positive feedback process that will accelerate the loss of Arctic sea ice.

  9. Orbital-Scale Cyclostratigraphy and Ice Volume Fluctuations from Arctic Ocean Sediments

    Science.gov (United States)

    Cronin, T. M.; Marzen, R.; DeNinno, L. H.

    2014-12-01

    Deep-sea foraminiferal oxygen isotope curves (δ18Of) are excellent paleoclimate records but are limited as proxies of global ice volume history during orbital glacial-interglacial cycles (GIC) due to the influence of deep-sea bottom water temperature, regional hydrography, ocean circulation and other factors affecting δ18Of. A more direct source of northern hemisphere [NH] ice history comes from central Arctic Ocean (CAO) submarine ridges (Northwind, Mendeleev, Lomonosov) where, at orbital timescales, sedimentation is controlled by the growth and decay of ice sheets, ice shelves, and sea ice. Calcareous microfossil density in CAO sediments is one of many proxies, such as manganese concentrations, grain size, bulk density, color, mineral content, organic geochemistry, and foraminiferal δ18O, that reveal GIC changes in ice cover, biological productivity, and primary and post-depositional sediment processes. In order to better understand NH ice history, we constructed 600-kyr-long stacked records of Arctic foraminiferal and ostracode density (AFD, AOD) from 19 CAO sediment cores following stacking and astronomical tuning procedures used for deep-sea δ18Of curves. Results show discrepancies between the Arctic AFD and AOD curves, the LR04 δ18Of stack (Lisiecki and Raymo 2005, Paleoceanography), the Red Sea and Mediterranean δ18Of sea level curves (Rohling et al. 2014 Nature), and modeled Antarctic Ice Sheet volume, suggesting asynchronous polar ice sheet behavior in the two hemispheres, notably during MIS 3, 5a, 5c, 7d, and 11.

  10. Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean.

    Science.gov (United States)

    Murton, Julian B; Bateman, Mark D; Dallimore, Scott R; Teller, James T; Yang, Zhirong

    2010-04-01

    The melting Laurentide Ice Sheet discharged thousands of cubic kilometres of fresh water each year into surrounding oceans, at times suppressing the Atlantic meridional overturning circulation and triggering abrupt climate change. Understanding the physical mechanisms leading to events such as the Younger Dryas cold interval requires identification of the paths and timing of the freshwater discharges. Although Broecker et al. hypothesized in 1989 that an outburst from glacial Lake Agassiz triggered the Younger Dryas, specific evidence has so far proved elusive, leading Broecker to conclude in 2006 that "our inability to identify the path taken by the flood is disconcerting". Here we identify the missing flood path-evident from gravels and a regional erosion surface-running through the Mackenzie River system in the Canadian Arctic Coastal Plain. Our modelling of the isostatically adjusted surface in the upstream Fort McMurray region, and a slight revision of the ice margin at this time, allows Lake Agassiz to spill into the Mackenzie drainage basin. From optically stimulated luminescence dating we have determined the approximate age of this Mackenzie River flood into the Arctic Ocean to be shortly after 13,000 years ago, near the start of the Younger Dryas. We attribute to this flood a boulder terrace near Fort McMurray with calibrated radiocarbon dates of over 11,500 years ago. A large flood into the Arctic Ocean at the start of the Younger Dryas leads us to reject the widespread view that Agassiz overflow at this time was solely eastward into the North Atlantic Ocean.

  11. Technetium-99 in the Nordic Seas and the Arctic Ocean 1970 - 2002: observations and model results

    Energy Technology Data Exchange (ETDEWEB)

    Karcher, M.J.; Iosjpe, M.; Harms, I.; Gerdes, R.; Christensen, G.C.; Dahlgaard, H.; Heldal, H.E.; Herrmann, J.; Leonard, K.S.; Kershaw, P.J.; Nies, H.; Gwynn, J.P. [Alfred Wegener Institute for Polar and Marine Research (Germany)

    2004-07-01

    Technetium-99 ({sup 99}Tc) is a highly soluble, beta emitting anthropogenic radionuclide with a half-life of 213000 years. The primary source of {sup 99}Tc to the northern marine environment has been through controlled discharges from the nuclear reprocessing facilities at Sellafield (UK) and Cap la Hague (France) which have taken place over several decades and have seen two periods of peak discharge in the 1970's and the 1990's. In the Nordic Seas, {sup 99}Tc is detected along the Norwegian Coastal Current (NCC) and further north, in the Barents Sea and West Spitsbergen Current. The further pathways of {sup 99}Tc are a recirculation with the East Greenland Current in the Nordic Seas and an intrusion into the Arctic Ocean proper with advective timescales of up to several decades. In the Norwegian Research Council (NFR) funded research project RADNOR, two state-of-the-art numerical models are used to simulate the fate of {sup 99}Tc discharges into the marine environment: The hydrodynamic coupled ice-ocean model NAOSIM, forced with realistic atmospheric data and the NRPA assessment box model which is forced by a fixed circulation pattern, but resolves the movement of the radionuclides in several environmental compartments. An intercomparison of the NAOSIM and NRPA model simulations of the dispersal of {sup 99}Tc will be performed followed by a comparison of the model simulations with an observational database. The database encompasses as complete as possible the available measurements from the West-European shelf seas northward into the Arctic Ocean. Results from this work will help to provide a better understanding of the dispersion dynamics of {sup 99}Tc in the Nordic Seas and the Arctic Ocean. (author)

  12. Decadal predictability of extreme fresh water export events from the Arctic Ocean into the Nordic Seas and subpolar North Atlantic

    Science.gov (United States)

    Schmith, Torben; Olsen, Steffen M.; Ringgaard, Ida M.; May, Wilhelm

    2016-04-01

    Abrupt fresh water releases originating in the Arctic Ocean have been documented to affect ocean circulation and climate in the North Atlantic area. Therefore, in this study, we investigate prospects for predicting such events up to one decade ahead. This is done in a perfect model setup by a combination of analyzing a 500 year control experiment and dedicated ensemble experiment aimed at predicting selected 10 year long segments of the control experiment. The selected segments are characterized by a large positive or negative trend in the total fresh water content in the Arctic Ocean. The analysis of the components (liquid fresh water and sea ice) reveals that they develop in a near random walk manner. From this we conclude that the main mechanism is integration of fresh water in the Beaufort Gyre through Ekman pumping from the randomly varying atmosphere. Therefore, the predictions from the ensemble experiments are on average not better than a damped persistence predictions. By running two different families of ensemble predictions, one starting from the 'observed' ocean globally, and one starting from climatology in the Arctic Ocean and from the observed ocean elsewhere, we conclude that the former outperforms the latter for the first few years as regards liquid fresh water and for the first year as regards sea ice. Analysis of the model experiments in terms of the fresh water export from the Arctic Ocean into Nordic seas and the subpolar North Atlantic reveals a very modest potential for predictability.

  13. Biased thermohaline exchanges with the Arctic across the Iceland-Faroe Ridge in ocean climate models

    Science.gov (United States)

    Olsen, S. M.; Hansen, B.; Østerhus, S.; Quadfasel, D.; Valdimarsson, H.

    2016-04-01

    The northern limb of the Atlantic thermohaline circulation and its transport of heat and salt towards the Arctic strongly modulate the climate of the Northern Hemisphere. The presence of warm surface waters prevents ice formation in parts of the Arctic Mediterranean, and ocean heat is directly available for sea-ice melt, while salt transport may be critical for the stability of the exchanges. Through these mechanisms, ocean heat and salt transports play a disproportionally strong role in the climate system, and realistic simulation is a requisite for reliable climate projections. Across the Greenland-Scotland Ridge (GSR) this occurs in three well-defined branches where anomalies in the warm and saline Atlantic inflow across the shallow Iceland-Faroe Ridge (IFR) have been shown to be particularly difficult to simulate in global ocean models. This branch (IF-inflow) carries about 40 % of the total ocean heat transport into the Arctic Mediterranean and is well constrained by observation during the last 2 decades but associated with significant inter-annual fluctuations. The inconsistency between model results and observational data is here explained by the inability of coarse-resolution models to simulate the overflow across the IFR (IF-overflow), which feeds back onto the simulated IF-inflow. In effect, this is reduced in the model to reflect only the net exchange across the IFR. Observational evidence is presented for a substantial and persistent IF-overflow and mechanisms that qualitatively control its intensity. Through this, we explain the main discrepancies between observed and simulated exchange. Our findings rebuild confidence in modelled net exchange across the IFR, but reveal that compensation of model deficiencies here through other exchange branches is not effective. This implies that simulated ocean heat transport to the Arctic is biased low by more than 10 % and associated with a reduced level of variability, while the quality of the simulated salt

  14. Biased thermohaline exchanges with the arctic across the Iceland-Faroe Ridge in ocean climate models

    Directory of Open Access Journals (Sweden)

    S. M. Olsen

    2015-07-01

    Full Text Available The northern limb of the Atlantic thermohaline circulation and its transport of heat and salt towards the Arctic strongly modulates the climate of the Northern Hemisphere. Presence of warm surface waters prevents ice formation in parts of the Arctic Mediterranean and ocean heat is in critical regions directly available for sea-ice melt, while salt transport may be critical for the stability of the exchanges. Hereby, ocean heat and salt transports play a disproportionally strong role in the climate system and realistic simulation is a requisite for reliable climate projections. Across the Greenland-Scotland Ridge (GSR this occurs in three well defined branches where anomalies in the warm and saline Atlantic inflow across the shallow Iceland-Faroe Ridge (IFR have shown particularly difficult to simulate in global ocean models. This branch (IF-inflow carries about 40 % of the total ocean heat transport into the Arctic Mediterranean and is well constrained by observation during the last two decades but is associated with significant inter-annual fluctuations. The inconsistency between model results and observational data is here explained by the inability of coarse resolution models to simulate the overflow across the IFR (IF-overflow, which feeds back on the simulated IF-inflow. In effect, this is reduced in the model to reflect only the net exchange across the IFR. Observational evidence is presented for a substantial and persistent IF-overflow and mechanisms that qualitatively control its intensity. Through this, we explain the main discrepancies between observed and simulated exchange. Our findings rebuild confidence in modeled net exchange across the IFR, but reveal that compensation of model deficiencies here through other exchange branches is not effective. This implies that simulated ocean heat transport to the Arctic is biased low by more than 10 % and associated with a reduced level of variability while the quality of the simulated salt

  15. The vertical structure of the atmospheric boundary layer over the central Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    BIAN Lingen; MA Yongfeng; LU Changgui; LIN Xiang

    2013-01-01

    The tropopause height and the atmospheric boundary layer (PBL) height as well as the variation of inversion layer above the floating ice surface are presented using GPS (global position system ) radiosonde sounding data and relevant data obtained by China’s fourth arctic scientific expedition team over the central Arctic Ocean (86◦-88◦N, 144◦-170◦W ) during the summer of 2010. The tropopause height is from 9.8 to 10.5 km, with a temperature range between-52.2 and-54.1◦C in the central Arctic Ocean. Two zones of maximum wind (over 12 m/s) are found in the wind profile, namely, low-and upper-level jets, located in the middle troposphere and the tropopause, respectively. The wind direction has a marked variation point in the two jets from the southeast to the southwest. The average PBL height determined by two methods is 341 and 453 m respectively. These two methods can both be used when the inversion layer is very low, but the results vary significantly when the inversion layer is very high. A significant logarithmic relationship exists between the PBL height and the inversion intensity, with a correlation coefficient of 0.66, indicating that the more intense the temperature inversion is, the lower the boundary layer will be. The observation results obviously differ from those of the third arctic expedition zone (80◦-85◦N). The PBL height and the inversion layer thickness are much lower than those at 87◦-88◦N, but the inversion temperature is more intense, meaning a strong ice-atmosphere interaction in the sea near the North Pole. The PBL structure is related to the weather system and the sea ice concentration, which affects the observation station.

  16. Igneous rocks of Arctic Ocean deep sea ridges: new data on petrology, geochemistry and geochronology

    Science.gov (United States)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey; Sobolev, Nikolay; Kashubin, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Belyatsky, Boris; Shatov, Vitaly; Petrov, Eugeny

    2015-04-01

    The aggregate results of studies of igneous rocks, collected from the central part of the Arctic Ocean during scientific marine expeditions «Arctic-2000, 2005, 2007 and 2012» are presented and discussed in the frame of modern understanding of High Polar Arctic tectonic constraint. Petrological, geochemical and isotope-geochronological studies of more than 500 samples have shown that the sedimentary rocks are of dominated population among the rock fragments dredged from deep-sea bottom, and represented by metamorphosed dolomite and quartz sandstone, limestone, sometimes with the Devonian - Permian fauna. Igneous rocks are 10-15% only (Archean and Paleoproterozoic gneissouse granites and gabbro, Neoproterozoic dolerite) and metamorphic rocks (green shales, metabasites, gneisses). Apparently, these rocks are part of the acoustic basement underlying the Late Mesozoic - Cenozoic layered loose sediments. In addition to the dredged fragments of the ancient mafic rocks, some samples were taken as a core during deep-water drilling in the northern and southern slopes of the Mendeleev Ridge and represented by trachybasalts, marking the border of Late-Cenozoic deposit cover and acoustic basement and quite similar in composition to those of Early-Late Cretaceous basalts form northward of the Chukchi Plateau seamounts, Alpha Ridge, Franz Josef Land, De Long islands and other parts of the large igneous province of the High Arctic (HALIP). Video-filming of Mendeleev Ridge escarps proofs the existing of rock outcrops and supports local origin of most of the rock fragments found in the sampling areas. Thus the continental type of the earth's crust of the Central Arctic Ridges basement is based on all obtained results of our study of sea-bottom excavated rock material.

  17. Mitigation implications of an ice-free summer in the Arctic Ocean

    Science.gov (United States)

    González-Eguino, Mikel; Neumann, Marc B.; Arto, Iñaki; Capellán-Perez, Iñigo; Faria, Sérgio H.

    2017-01-01

    The rapid loss of sea ice in the Arctic is one of the most striking manifestations of climate change. As sea ice melts, more open water is exposed to solar radiation, absorbing heat and generating a sea-ice-albedo feedback that reinforces Arctic warming. Recent studies stress the significance of this feedback mechanism and suggest that ice-free summer conditions in the Arctic Ocean may occur faster than previously expected, even under low-emissions pathways. Here we use an integrated assessment model to explore the implications of a potentially rapid sea-ice-loss process. We consider a scenario leading to a full month free of sea ice in September 2050, followed by three potential trajectories afterward: partial recovery, stabilization, and continued loss of sea ice. We analyze how these scenarios affect the efforts to keep global temperature increase below 2°C. Our results show that sea-ice melting in the Arctic requires more stringent mitigation efforts globally. We find that global CO2 emissions would need to reach zero levels 5-15 years earlier and that the carbon budget would need to be reduced by 20%-51% to offset this additional source of warming. The extra mitigation effort would imply an 18%-59% higher mitigation cost to society. Our results also show that to achieve the 1.5°C target in the presence of ice-free summers negative emissions would be needed. This study highlights the need for a better understanding of how the rapid changes observed in the Arctic may impact our society.

  18. Evolution of high Arctic ocean basins and continental margins

    Energy Technology Data Exchange (ETDEWEB)

    Engen, Oeyvind

    2005-08-01

    Taking advantage of the much increased detail offered by new data, the dissertation attempts to answer some of the remaining questions about the ocean basins and continental margins flanking the Eurasia-North America plate boundary. Its four constituent papers result from integrated geophysical analysis of gravity and magnetic anomalies, bathymetry, seismic reflection and refraction profiles, earthquake locations and focal mechanisms, and onshore and offshore geological data. The overall objectives are to: 1) Elucidate aspects of the structure, composition and evolution of the Eurasia Basin and Norwegian-Greenland Sea and their passive continental margins. 2) Relate the findings to fundamental Earth processes, specifically associated with lithospheric break-up and seafloor spreading. Summary of Papers: The present-day global seismograph network is capable of detecting earthquakes with nearly uniform magnitude threshold throughout the Eurasia Basin region. Given that the location of each earthquake is constrained by at least 12 recording stations, global earthquake catalogues confidently show that 1) earthquakes along the oceanic part of the plate boundary occur in swarms; 2) plate boundary stress decreases eastwards, in accordance with decreasing spreading rates; and 3) deformation takes place in a narrow zone in the oceanic domain but is abruptly defocused at the transition to the Laptev Sea continental rift system. When integrated with bathymetry and potential field data, the earthquake distribution indicates four distinct plate boundary provinces. The Spitsbergen Transform System is a series of oblique ridges and transform faults where the seismicity becomes increasingly diffuse to the north. The western Gakkel Ridge (west of 60{sup E}) has clustered and focused seismicity, accentuated topography and highamplitude magnetic anomalies, whereas the eastern Gakkel Ridge has smoother topographic relief, lower magnetic amplitudes, and slightly more focused seismicity

  19. Collection of Arctic Ocean Data from US Navy Submarines on the New SCICEX Program

    Science.gov (United States)

    Smethie, W. M.; Sambrotto, R.; Boyd, T.; Richter-Menge, J.; Corbett, J.

    2011-12-01

    The SCICEX submarine Arctic science program originated in the 1990s when six dedicated science cruises were conducted in the Arctic Ocean aboard US Navy Sturgeon class submarines. After the cold war era Sturgeon class submarines were retired, several Science Accommodation cruises, for which a few days for scientific measurements were added to planned submarine transits through the Arctic Ocean, were carried out when opportunities arose. Renewed interest in conducting further Science Accommodation cruises on a regular basis to better document and understand how the Arctic Ocean responds to climate change resulted in publication of a scientific plan in 2010 (http://www.arctic.gov/publications/scicex_plan.pdf). In the spring of 2011 testing of data collection and water sampling methods aboard newer Virginia and Seawolf class submarines on transit from a Navy ice camp in the Beaufort Sea, was conducted in order to develop protocols and evaluate techniques. Ice draft measurements were also taken in the vicinity of the ice camp and near the North Pole to evaluate new data collection systems. This evaluation will include a comparison of the ice draft data with a comprehensive set of in situ ice thickness measurements taken near the ice camp. Under-ice submarine-launched eXpendable Condutivity Temperature Depth (XCTD) probes were deployed from the USS Connecticut (SSN-22), a Seawolf class submarine, and the resulting profiles compared to CTD casts from the APLIS ice station and historical profiles. Water samples were collected through the hull for measurements of tritium, helium isotopes, oxygen isotopes, chlorofluorocarbons, sulfur hexafluoride, nutrients, dissolved organic carbon, bacterioplankton, phytoplankton and particulates levels. These samples were returned to Lamont-Doherty Earth Observatory and were in the process of being measured at the time this abstract was written. Measurements completed at this time indicate good samples can be collected for CFC-12

  20. Absolute Geostrophic Velocity Inverted from the Polar Science Center Hydrographic Climatology (PHC3.0) of the Arctic Ocean with the P-Vector Method (NCEI Accession 0156425)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset (called PHC-V) comprises 3D gridded climatological fields of absolute geostrophic velocity of the Arctic Ocean inverted from the Polar science center...

  1. Temperature, salinity, and other data from buoy casts in the Arctic Ocean, Barents Sea and Beaufort Sea from 1948 to 1993 (NODC Accession 9800040)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, and other data were collected using buoy casts in the Arctic Ocean, Barents Sea and Beaufort Sea from 1948 to 1993. Data were collected by the...

  2. Zooplankton species identification and counts data from drifting station ARLIS II and Fletchers ice island T-3 in the Arctic Ocean from 19521229 to 19680129 (NODC Accession 6900643)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are counts of 3 copepod species collected during plankton tows in the Arctic Ocean from December 1952 through January 1968 by the University of...

  3. Oceanographic station data from bottle casts from the T-3 in the Arctic Ocean from 29 May 1958 to 17 June 1958 (NODC Accession 7601275)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Oceanographic station data were collected from the T-3 in the Arctic Ocean. Data were collected by the Fisheries Research Board of Canada; Atlantic Oceanographic...

  4. Phytoplankton data collected using net casts in the Arctic Ocean from the USCGC POLAR SEA from 26 July 1994 to 26 August 1994 (NODC Accession 0000770)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Phytoplankton data were collected using net casts from the USCGC POLAR SEA in the Arctic Ocean. Data were collected from 26 July 1994 to 26 August 1994. Data were...

  5. Temperature profile, pressure, and chemical data from XBT, bottle, CTD casts in the Arctic Ocean from 06 May 2003 to 06 May 2004 (NODC Accession 0002203)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile, pressure, and chemical data were collected using XBT, bottle, and CTD casts in the Arctic Ocean from May 6, 2003 to May 5, 2004. Data were...

  6. Temperature, salinity, and other data from CTD and XCTD casts in the Arctic Ocean from 26 March 1995 to 08 May 1995 (NODC Accession 0000474)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD, XCTD, and other data were collected in the Arctic Ocean from 26 March 1995 to 08 May 1995. Surface data were collected by CTD. XCTD data were corrected for...

  7. High numbers of heat-loving bacteria found in cold Arctic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2009-09-15

    This article reported on a study of subzero sediments in the Arctic Ocean off the Norwegian island of Spitsbergen where scientists from the University of Calgary detected high numbers of thermophilic bacteria. The spores may offer an opportunity to trace seepages of fluids from hot sub-seafloor habitats and potentially indicate undiscovered offshore petroleum reservoirs. The Arctic spores that appear to have been transported from deeper hot spots were revived during experimental incubations at 40 to 60 degrees Celsius. Ongoing surveys are expected to identify the source, or sources, of these misplaced microbes. Since these bacteria are anaerobic, their high abundance and steady supply into the sediments indicate they are coming from a large oxygen-free habitat. One possible source may be a deep pressurized oil reservoir from which upward-leaking hydrocarbons carry bacteria into overlying seawater. Another source could be related to fluid circulation through warm ocean crust at spreading ridges. The thermophiles may get carried out of the abyssal hot spots by ocean currents that disperse them to the cold sediments. The spores also offer insight for understanding how biodiversity is maintained by the passive dispersal of small cells over large distances.

  8. Mercury export to the Arctic Ocean from the Mackenzie River, Canada.

    Science.gov (United States)

    Emmerton, Craig A; Graydon, Jennifer A; Gareis, Jolie A L; St Louis, Vincent L; Lesack, Lance F W; Banack, Janelle K A; Hicks, Faye; Nafziger, Jennifer

    2013-07-16

    Circumpolar rivers, including the Mackenzie River in Canada, are sources of the contaminant mercury (Hg) to the Arctic Ocean, but few Hg export studies exist for these rivers. During the 2007-2010 freshet and open water seasons, we collected river water upstream and downstream of the Mackenzie River delta to quantify total mercury (THg) and methylmercury (MeHg) concentrations and export. Upstream of the delta, flow-weighted mean concentrations of bulk THg and MeHg were 14.6 ± 6.2 ng L(-1) and 0.081 ± 0.045 ng L(-1), respectively. Only 11-13% and 44-51% of bulk THg and MeHg export was in the dissolved form. Using concentration-discharge relationships, we calculated bulk THg and MeHg export into the delta of 2300-4200 kg yr(-1) and 15-23 kg yr(-1) over the course of the study. Discharge is not presently known in channels exiting the delta, so we assessed differences in river Hg concentrations upstream and downstream of the delta to estimate its influence on Hg export to the ocean. Bulk THg and MeHg concentrations decreased 19% and 11% through the delta, likely because of particle settling and other processes in the floodplain. These results suggest that northern deltas may be important accumulators of river Hg in their floodplains before export to the Arctic Ocean.

  9. Comparison of Hygroscopicity, Volatility, and Mixing State of Submicrometer Particles between Cruises over the Arctic Ocean and the Pacific Ocean.

    Science.gov (United States)

    Kim, Gibaek; Cho, Hee-Joo; Seo, Arom; Kim, Dohyung; Gim, Yeontae; Lee, Bang Yong; Yoon, Young Jun; Park, Kihong

    2015-10-20

    Ship-borne measurements of ambient aerosols were conducted during an 11 937 km cruise over the Arctic Ocean (cruise 1) and the Pacific Ocean (cruise 2). A frequent nucleation event was observed during cruise 1 under marine influence, and the abundant organic matter resulting from the strong biological activity in the ocean could contribute to the formation of new particles and their growth to a detectable size. Concentrations of particle mass and black carbon increased with increasing continental influence from polluted areas. During cruise 1, multiple peaks of hygroscopic growth factor (HGF) of 1.1-1.2, 1.4, and 1.6 were found, and higher amounts of volatile organic species existed in the particles compared to that during cruise 2, which is consistent with the greater availability of volatile organic species caused by the strong oceanic biological activity (cruise 1). Internal mixtures of volatile and nonhygroscopic organic species, nonvolatile and less-hygroscopic organic species, and nonvolatile and hygroscopic nss-sulfate with varying fractions can be assumed to constitute the submicrometer particles. On the basis of elemental composition and morphology, the submicrometer particles were classified into C-rich mixture, S-rich mixture, C/S-rich mixture, Na-rich mixture, C/P-rich mixture, and mineral-rich mixture. Consistently, the fraction of biological particles (i.e., P-containing particles) increased when the ship traveled along a strongly biologically active area.

  10. Storm-driven Mixing and Potential Impact on the Arctic Ocean

    Science.gov (United States)

    Yang, Jiayan; Comiso, Josefino; Walsh, David; Krishfield, Richard; Honjo, Susumu; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Observations of the ocean, atmosphere, and ice made by Ice-Ocean Environmental Buoys (IOEBs) indicate that mixing events reaching the depth of the halocline have occurred in various regions in the Arctic Ocean. Our analysis suggests that these mixing events were mechanically forced by intense storms moving across the buoy sites. In this study, we analyzed these mixing events in the context of storm developments that occurred in the Beaufort Sea and in the general area just north of Fram Strait, two areas with quite different hydrographic structures. The Beaufort Sea is strongly influenced by inflow of Pacific water through Bering Strait, while the area north of Fram Strait is directly affected by the inflow of warm and salty North Atlantic water. Our analyses of the basin-wide evolution of the surface pressure and geostrophic wind fields indicate that the characteristics of the storms could be very different. The buoy-observed mixing occurred only in the spring and winter seasons when the stratification was relatively weak. This indicates the importance of stratification, although the mixing itself was mechanically driven. We also analyze the distribution of storms, both the long-term climatology as well as the patterns for each year in the last two decades. The frequency of storms is also shown to be correlated- (but not strongly) to Arctic Oscillation indices. This study indicates that the formation of new ice that leads to brine rejection is unlikely the mechanism that results in the type of mixing that could overturn the halocline. On the other hand, synoptic-scale storms can force mixing deep enough to the halocline and thermocline layer. Despite a very stable stratification associated with the Arctic halocline, the warm subsurface thermocline water is not always insulated from the mixed layer.

  11. Methane and nitrous oxide distributions across the North American Arctic Ocean during summer, 2015

    Science.gov (United States)

    Fenwick, Lindsay; Capelle, David; Damm, Ellen; Zimmermann, Sarah; Williams, William J.; Vagle, Svein; Tortell, Philippe D.

    2017-01-01

    We collected Arctic Ocean water column samples for methane (CH4) and nitrous oxide (N2O) analysis on three separate cruises in the summer and fall of 2015, covering a ˜10,000 km transect from the Bering Sea to Baffin Bay. This provided a three-dimensional view of CH4 and N2O distributions across contrasting hydrographic environments, from the oligotrophic waters of the deep Canada Basin and Baffin Bay, to the productive shelves of the Bering and Chukchi Seas. Percent saturation relative to atmospheric equilibrium ranged from 30 to 800% for CH4 and 75 to 145% for N2O, with the highest concentrations of both gases occurring in the northern Chukchi Sea. Nitrogen cycling in the shelf sediments of the Bering and Chukchi Seas likely constituted the major source of N2O to the water column, and the resulting high N2O concentrations were transported across the Arctic Ocean in eastward-flowing water masses. Methane concentrations were more spatially heterogeneous, reflecting a variety of localized inputs, including likely sources from sedimentary methanogenesis and sea ice processes. Unlike N2O, CH4 was rapidly consumed through microbial oxidation in the water column, as shown by the 13C enrichment of CH4 with decreasing concentrations. For both CH4 and N2O, sea-air fluxes were close to neutral, indicating that our sampling region was neither a major source nor sink of these gases. Our results provide insight into the factors controlling the distribution of CH4 and N2O in the North American Arctic Ocean, and an important baseline data set against which future changes can be assessed.

  12. The Role and Variability of Ocean Heat Content in the Arctic Ocean: 1948-2009

    Science.gov (United States)

    2014-06-01

    Andrew Roberts THIS PAGE INTENTIONALLY LEFT BLANK i REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this...Technical Commission for Oceanography and Marine Meteorology LANL Los Alamos National Laboratory MLD mixed layer depth N 2 Buoyancy frequency NAME...respect to the Arctic. The National Security Strategy is the fundamental document upon which strategic planning is derived, and it states that the

  13. Relevance of dissolved organic nutrients for the Arctic Ocean nutrient budget

    Science.gov (United States)

    Torres-Valdés, Sinhué; Tsubouchi, Takamasa; Davey, Emily; Yashayaev, Igor; Bacon, Sheldon

    2016-06-01

    We ask whether dissolved organic nitrogen (DON) and phosphorus (DOP) could account for previously identified Arctic Ocean (AO) inorganic nutrient budget imbalances. We assess transports to/from the AO by calculating indicative budgets. Marked DON:DOP ratio differences between the Amerasian and Eurasian AO reflect different physical and biogeochemical pathways. DON and DOP are exported to the North Atlantic via Davis Strait potentially being enhanced in transit from Bering Strait. Fram Strait transports are balanced. Barents Sea Opening transports may provide an additional nutrient source to the Barents Sea or may be locked within the wider AO Atlantic Water circulation. Gaps in our knowledge are identified and discussed.

  14. Remote sensing the dynamics of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean)

    Science.gov (United States)

    Doxaran, D.; Ehn, J.; Bélanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-04-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. A direct consequence is an increase in Arctic river discharge with an expectation of increased delivery of organic carbon sequestered in high-latitute soils since the last glacial maximum. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed to an operational stage. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC:SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is validated based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone within which terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future work require the validation of the developed SPM regional algorithm based

  15. Planktic foraminifer census data from Northwind Ridge Core 5, Arctic Ocean

    Science.gov (United States)

    Foley, Kevin M.; Poore, Richard Z.

    1991-01-01

    The U.S. Geological Survey recovered 9 piston cores from the Northwind Ridge in the Canada Basin of the Arctic Ocean from a cruise of the USCGC Polar Star during 1988. Preliminary analysis of the cores suggests sediments deposited on Northwind Ridge preserve a detailed record of glacial and interglacial cycles for the last few hundred-thousand to one million years. This report includes quantitative data on foraminifers and selected sediment size-fraction data in samples from Northwind Ridge core PI-88AR P5.

  16. Phylogenetic analysis of bacteria in sea ice brine sampled from the Canada Basin, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Bacterial diversity in sea ice brine samples which collected from four stations located at the Canada Basin, Arctic Ocean was analyzed by PCR-DGGE. Twenty-three 16S rDNA sequences of bacteria obtained from DGGE bands were cloned and sequenced. Phylogenetic analysis clustered these sequences within γ-proteobacteria, Cytophaga-Flexibacter-Bacteroides (CFB) group, Firmicutes and Actinobacteria. The phylotype of Pseudoalteromonas in the γ-proteobacteria was predominant and members of the CFB group and γ-proteobacteria were highly abundant in studied sea ice brine samples.

  17. Remote sensing the dynamics of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean

    Directory of Open Access Journals (Sweden)

    D. Doxaran

    2012-04-01

    Full Text Available Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. A direct consequence is an increase in Arctic river discharge with an expectation of increased delivery of organic carbon sequestered in high-latitute soils since the last glacial maximum. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed to an operational stage.

    The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM on the Mackenzie River continental shelf (Canadian Arctic Ocean using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC. Robust SPM and POC:SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is validated based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone within which terrigenous SPM is mainly constrained (out of short periods of maximum river outflow. Most of the seaward export of SPM is observed to occur within the west side of the river mouth.

    Future work require the validation of the

  18. How does the SST variability over the western North Atlantic Ocean control Arctic warming over the Barents–Kara Seas?

    Science.gov (United States)

    Jung, Ok; Sung, Mi-Kyung; Sato, Kazutoshi; Lim, Young-Kwon; Kim, Seong-Joong; Baek, Eun-Hyuk; Jeong, Jee-Hoon; Kim, Baek-Min

    2017-03-01

    Arctic warming over the Barents–Kara Seas and its impacts on the mid-latitude circulations have been widely discussed. However, the specific mechanism that brings the warming still remains unclear. In this study, a possible cause of the regional Arctic warming over the Barents–Kara Seas during early winter (October–December) is suggested. We found that warmer sea surface temperature anomalies over the western North Atlantic Ocean (WNAO) modulate the transient eddies overlying the oceanic frontal region. The altered transient eddy vorticity flux acts as a source for the Rossby wave straddling the western North Atlantic and the Barents–Kara Seas (Scandinavian pattern), and induces a significant warm advection, increasing surface and lower-level temperature over the Eurasian sector of the Arctic Ocean. The importance of the sea surface temperature anomalies over the WNAO and subsequent transient eddy forcing over the WNAO was also supported by both specially designed simple model experiments and general circulation model experiments.

  19. Under-ice distribution of polar cod Boreogadus saida in the central Arctic Ocean and their association with sea-ice habitat properties

    NARCIS (Netherlands)

    David, Carmen; Lange, Benjamin; Krumpen, Thomas; Schaafsma, F.L.; Franeker, van J.A.; Flores, H.

    2016-01-01

    In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean, ho

  20. Sources and cycling of mercury in the paleo Arctic Ocean from Hg stable isotope variations in Eocene and Quaternary sediments

    Science.gov (United States)

    Gleason, J. D.; Blum, J. D.; Moore, T. C.; Polyak, L.; Jakobsson, M.; Meyers, P. A.; Biswas, A.

    2017-01-01

    Mercury stable isotopic compositions were determined for marine sediments from eight locations in the Arctic Ocean Basin. Mass dependent fractionation (MDF) and mass independent fractionation (MIF) of Hg stable isotopes were recorded across a variety of depositional environments, water depths, and stratigraphic ages. δ202Hg (MDF) ranges from -2.34‰ to -0.78‰; Δ199Hg (MIF) from -0.18‰ to +0.12‰; and Δ201Hg (MIF) from -0.29‰ to +0.05‰ for the complete data set (n = 33). Holocene sediments from the Chukchi Sea and Morris Jesup Rise record the most negative Δ199Hg values, while Pleistocene sediments from the Central Arctic Ocean record the most positive Δ199Hg values. The most negative δ202Hg values are recorded in Pleistocene sediments. Eocene sediments (Lomonosov Ridge) show some overlap in their Hg isotopic compositions with Quaternary sediments, with a sample of the Arctic Ocean PETM (56 Ma) most closely matching the average Hg isotopic composition of Holocene Arctic marine sediments. Collectively, these data support a terrestrially-dominated Hg source input for Arctic Ocean sediment through time, although other sources, as well as influences of sea ice, atmospheric mercury depletion events (AMDEs), and anthropogenic Hg (in core top samples) on Hg isotopic signatures must also be considered.

  1. Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

    Science.gov (United States)

    Shen, Y.; Fichot, C. G.; Benner, R.

    2012-12-01

    Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High concentrations and yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Concentrations and yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p productivity in the western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi Sea implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the central Arctic basins.

  2. Profile and meteorological data collected for the Atlantic Layer Tracking Experiment in the Arctic Ocean, Greenland Sea, and North Pacific Ocean, from 2001-05 to 2001-11 (NCEI Accession 0001111)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Depth, pressure, salinity, temperature, and other data were collected using meteorological sensors and CTD casts in the Arctic Ocean, Greenland Sea, and North...

  3. Ship accessibility predictions for the Arctic Ocean based on IPCC CO2 emission scenarios

    Science.gov (United States)

    Oh, Jai-Ho; Woo, Sumin; Yang, Sin-Il

    2017-02-01

    Changes in the extent of Arctic sea ice, which have resulted from climate change, offer new opportunities to use the Northern Sea Route (NSR) and Northwest Passage (NWP) for shipping. However, choosing to navigate the Arctic Ocean remains challenging due to the limited accessibility of ships and the balance between economic gain and potential risk. As a result, more precise and detailed information on both weather and sea ice change in the Arctic are required. In this study, a high-resolution global AGCM was used to provide detailed information on the extent and thickness of Arctic sea ice. For this simulation, we have simulated the AMIP-type simulation for the present-day climate during 31 years from 1979 to 2009 with observed SST and Sea Ice concentration. For the future climate projection, we have performed the historical climate during 1979-2005 and subsequently the future climate projection during 2010-2099 with mean of four CMIP5 models due to the two Representative Concentration Pathway scenarios (RCP 8.5 and RCP 4.5). First, the AMIP-type simulation was evaluated by comparison with observations from the Hadley Centre sea-ice and Sea Surface Temperature (HadlSST) dataset. The model reflects the maximum (in March) and minimum (in September) sea ice extent and annual cycle. Based on this validation, the future sea ice extents show the decreasing trend for both the maximum and minimum seasons and RCP 8.5 shows more sharply decreasing patterns of sea ice than RCP 4.5. Under both scenarios, ships classified as Polar Class (PC) 3 and Open-Water (OW) were predicted to have the largest and smallest number of ship-accessible days (in any given year) for the NSR and NWP, respectively. Based on the RCP 8.5 scenario, the projections suggest that after 2070, PC3 and PC6 vessels will have year-round access across to the Arctic Ocean. In contrast, OW vessels will continue to have a seasonal handicap, inhibiting their ability to pass through the NSR and NWP.

  4. Summertime calcium carbonate undersaturation in shelf waters of the western Arctic Ocean – how biological processes exacerbate the impact of ocean acidification

    Directory of Open Access Journals (Sweden)

    N. R. Bates

    2013-08-01

    Full Text Available The Arctic Ocean accounts for only 4% of the global ocean area, but it contributes significantly to the global carbon cycle. Recent observations of seawater CO2-carbonate chemistry in shelf waters of the western Arctic Ocean, primarily in the Chukchi Sea, from 2009 to 2011 indicate that bottom waters are seasonally undersaturated with respect to calcium carbonate (CaCO3 minerals, particularly aragonite. Nearly 40% of sampled bottom waters on the shelf have saturation states less than one for aragonite (i.e., Ωaragonite 3-secreting organisms, while 80% of bottom waters present had Ωaragonite values less than 1.5. Our observations indicate seasonal reduction of saturation states (Ω for calcite (Ωcalcite and aragonite (Ωaragonite in the subsurface in the western Arctic by as much as 0.8 and 0.5, respectively. Such data indicate that bottom waters of the western Arctic shelves were already potentially corrosive for biogenic and sedimentary CaCO3 for several months each year. Seasonal changes in Ω are imparted by a variety of factors such as phytoplankton photosynthesis, respiration/remineralization of organic matter and air–sea gas exchange of CO2. Combined, these processes either increase or enhance in surface and subsurface waters, respectively. These seasonal physical and biological processes also act to mitigate or enhance the impact of Anthropocene ocean acidification (OA on Ω in surface and subsurface waters, respectively. Future monitoring of the western Arctic shelves is warranted to assess the present and future impact of ocean acidification and seasonal physico-biogeochemical processes on Ω values and Arctic marine ecosystems.

  5. Seasonal heat and freshwater cycles in the Arctic Ocean in CMIP5 coupled models

    Science.gov (United States)

    Ding, Yanni; Carton, James A.; Chepurin, Gennady A.; Steele, Michael; Hakkinen, Sirpa

    2016-04-01

    This study examines the processes governing the seasonal response of the Arctic Ocean and sea ice to surface forcings as they appear in historical simulations of 14 Coupled Model Intercomparison Project Phase 5 coupled climate models. In both models and observations, the seasonal heat budget is dominated by a local balance between net surface heating and storage in the heat content of the ocean and in melting/freezing of sea ice. Observations suggest ocean heat storage is more important than sea ice melt, while in most of these models, sea ice melt dominates. Seasonal horizontal heat flux divergence driven by the seasonal cycle of volume transport is only important locally. In models and observations, the dominant terms in the basin-average seasonal freshwater budget are the storages of freshwater between the ocean and sea ice, and the exchange between the two. The largest external source term is continental discharge in early summer, which is an order of magnitude smaller. The appearance of sea ice (extent and volume) and also ocean stratification in both the heat and freshwater budgets provides two links between the budgets and provides two mechanisms for feedback. One consequence of such an interaction is the fact that models with strong/weak seasonal surface heating also have strong/weak seasonal haline and temperature stratification.

  6. Changing summer sea ice roughness modifies momentum transfer into the Arctic Ocean

    Science.gov (United States)

    Martin, Torge; Tsamados, Michel; Feltham, Daniel

    2015-04-01

    The current shrinking of Arctic sea ice affects the transfer of momentum from the atmosphere into the ocean. While in winter a thinner and thus weaker sea ice cover enables a greater ocean surface stress than in previous decades, the enormous retreat of sea ice in recent summers reduced the surface roughness of the Arctic Ocean and hence causes a negative ocean surface stress trend in this season. The latter is related to a generally enhanced surface drag in the presence of sea ice. Martin et al. (2014, JGR) suggested that such amplification of momentum transfer by ice floes peaks at an optimal ice concentration of 80-90% -- since higher concentrations damp momentum transfer due to ice internal stresses. However, this model study only considered a constant sea ice roughness in the calculation of the surface stress. Tsamados et al. (2014, JPO) recently implemented complex variable sea-ice drag coefficients into the sea ice model CICE also distinguishing between skin and form drag. They showed in stand-alone sea ice simulations that varying sea ice roughness due to, amongst others, pressure ridges and floe edges significantly impacts sea ice motion likely with implications for the ocean circulation underneath. Here, we present the effect of variable sea ice drag on the ocean surface stress. A comparison of the CICE results with Martin et al. (2014, JGR) shows that on basin-wide average the ice concentration-ocean stress relationship still peaks at about 80-90% but stress increases more rapidly with increasing ice concentration forming a "plateau" at 40-70%. We find that pressure ridges contribute more to the 80-90% peak whereas floe edges and skin drag shape the plateau. Further, Tsamados et al. (2014, JPO) found for the summer season that floe edges dominate the ice-water drag magnitude and that an increase in the floe edge form drag dominates the overall ice-water drag trend over the past two decades. This hints at the possibility that a favorable floe size

  7. Validation of satellite data with IASOA observatories and shipboard measurements in Arctic Ocean

    Science.gov (United States)

    Repina, Irina; Artamonov, Arseniy; Mazilkina, Alexandra; Valiullin, Denis; Stanichny, Sergey

    2016-04-01

    The paper shows the possibility of using surface observation data at high latitudes for the validation of different satellite products. We use data from International Arctic Systems for Observing the Atmosphere (IASOA) observatories and data from Nansen and Amundsen basins observation system (NABOS) project. The NABOS field experiment was carried out in the central part of the Arctic and in the eastern Arctic seas during summer and fall period of 2004-2009, 2013 and 2015. Newly improved satellite products and surface observations provide an opportunity to revisit remote-sensing capabilities for estimating shortwave and longwave radiative fluxes, as well as turbulent fluxes at high latitudes. Estimates of SW fluxes from the MODIS and LW fluxes from the NOAA satellites are evaluated against land observations from IASOA observatories, and unique shipboard measurements. Results show that the satellite products are in better agreement with observations than those from numerical models. Therefore, the large scale satellite based estimates should be useful for model evaluation and for providing information in formulating energy budgets at high latitudes. Visible and near-infrared albedos over snow and ice surfaces are retrieved from AVHRR. Comparison with surface measurements of albedo in arctic observatories and Arctic ocean shows very good agreement. Meteorological and micrometeorological observations were used to validate the surface temperature and surface heat fluxes in the satellite data. Compared data arrays are independent and sufficiently detailed to perform trustworthy evaluations. The spatial and temporal patterns of the resulting flux fields are investigated and compared with those derived from satellite observations such as HOAPS, from blended data such as AOFLUX (in the open water cases). A computation of the sensible heat flux at the surface is formulated on the basis of spatial variations of the surface temperature estimated from satellite data. Based on

  8. HY-2A satellite altimetric data evaluation in the Arctic ocean

    DEFF Research Database (Denmark)

    Cheng, Yongcun; Andersen, Ole Baltazar

    2014-01-01

    in the Arctic Ocean. The results demonstrates that the HY-2 data shows higher standard variation and mean sea level than AltiKa and CryoSat-2 data during HY-2 cycle 49 (20130803 and 20130817) with more available sea level measurements than CryoSat-2 satellite altimetry. Moreover, consistent sea level variation......HY-2A (‘HaiYang’ denotes Ocean) was launched in August 2011. It payloads Ku and C bands radar altimeters with repeat cycles of 14 days (for three years) and 168 days. In the present study, we preliminary evaluate the HY-2 satellite altimetric data against SARAL/AltiKa and CryoSat-2 data...

  9. Effects of tides on Riverine and Glacial freshwater transport in the Arctic Ocean.

    Science.gov (United States)

    Luneva, Maria; Aksenov, Yevgeny; Harle, James; Holt, Jason

    2016-04-01

    In this study we use a novel pan-Arctic sea NENO-shelf ice-ocean coupled model, to examine the effects of tides, river runoff and vertical mixing schemes on sea ice and the mixing of water masses. Several 20-year long (1990-2010) simulations were performed: with explicitly resolved tides and without any tidal dynamics, with climatology river runoff, Dai et al. ,2009 database and freshwater source from melting Greenland glaciers. We examine also three different turbulent closures structural functions, based on the k-epsilon version of the Generic Length Scale Model: by Canuto group (2001) and two by Kantha and Clayson (1994, 2004). The results have been compared with sea ice volume and concentration trends and temperature and salinity profiles from World Ocean Database . We compared the following characteristics: potential energy anomalies, depth of halocline, mixed layer depth , salinity at the subsurface layer.

  10. Monitoring and assessment of ocean acidification in the Arctic Ocean-A scoping paper

    Science.gov (United States)

    Robbins, Lisa L.; Yates, Kimberly K.; Feely, Richard; Fabry, Victoria

    2010-01-01

    Carbon dioxide (CO2) in the atmosphere is absorbed at the ocean surface by reacting with seawater to form a weak, naturally occurring acid called carbonic acid. As atmospheric carbon dioxide increases, the concentration of carbonic acid in seawater also increases, causing a decrease in ocean pH and carbonate mineral saturation states, a process known as ocean acidification. The oceans have absorbed approximately 525 billion tons of carbon dioxide from the atmosphere, or about one-quarter to one-third of the anthropogenic carbon emissions released since the beginning of the Industrial Revolution. Global surveys of ocean chemistry have revealed that seawater pH has decreased by about 0.1 units (from a pH of 8.2 to 8.1) since the 1700s due to absorption of carbon dioxide (Raven and others, 2005). Modeling studies, based on Intergovernmental Panel on Climate Change (IPCC) CO2 emission scenarios, predict that atmospheric carbon dioxide levels could reach more than 500 parts per million (ppm) by the middle of this century and 800 ppm by the year 2100, causing an additional decrease in surface water pH of 0.3 pH units. Ocean acidification is a global threat and is already having profound and deleterious effects on the geology, biology, chemistry, and socioeconomic resources of coastal and marine habitats. The polar and sub-polar seas have been identified as the bellwethers for global ocean acidification.

  11. Sea ice phenology and timing of primary production pulses in the Arctic Ocean.

    Science.gov (United States)

    Ji, Rubao; Jin, Meibing; Varpe, Øystein

    2013-03-01

    Arctic organisms are adapted to the strong seasonality of environmental forcing. A small timing mismatch between biological processes and the environment could potentially have significant consequences for the entire food web. Climate warming causes shrinking ice coverage and earlier ice retreat in the Arctic, which is likely to change the timing of primary production. In this study, we test predictions on the interactions among sea ice phenology and production timing of ice algae and pelagic phytoplankton. We do so using the following (1) a synthesis of available satellite observation data; and (2) the application of a coupled ice-ocean ecosystem model. The data and model results suggest that, over a large portion of the Arctic marginal seas, the timing variability in ice retreat at a specific location has a strong impact on the timing variability in pelagic phytoplankton peaks, but weak or no impact on the timing of ice-algae peaks in those regions. The model predicts latitudinal and regional differences in the timing of ice algae biomass peak (varying from April to May) and the time lags between ice algae and pelagic phytoplankton peaks (varying from 45 to 90 days). The correlation between the time lag and ice retreat is significant in areas where ice retreat has no significant impact on ice-algae peak timing, suggesting that changes in pelagic phytoplankton peak timing control the variability in time lags. Phenological variability in primary production is likely to have consequences for higher trophic levels, particularly for the zooplankton grazers, whose main food source is composed of the dually pulsed algae production of the Arctic.

  12. Contrasted climatic trends in the Atlantic vs. Pacific gateways of the Arctic Ocean during the Holocene

    Science.gov (United States)

    de Vernal, A.; Hillaire-Marcel, C.; Rochon, A.

    2013-12-01

    The reconstruction of sea-surface conditions including sea ice cover was undertaken based on about 20 marine sediment cores collected in the Arctic Ocean and subarctic seas. The approach has been standardized and mostly relies on the modern analogue technique applied to dinoflagellate cyst assemblages, which permit simultaneous estimates of sea ice cover, summer sea-surface temperature and salinity. The results show some regionalism in both trends, amplitude and overall variability. In general, changes of small amplitude are recorded in the Canadian Arctic whereas a slight cooling trend with an increasing sea ice cover characterizes the Northern Baffin Bay and Fram Strait areas from mid to late Holocene. In contrast, the Chukchi Sea records show large amplitude variations with millennial pacing making difficult to define any trend. The Chukchi Sea data indicate reduced sea ice and warmer conditions during the mid-Holocene, notably around 6.5 and 3.5 ka, and also point to important variations during the last millennium. The overall results suggest a higher variability thus sensitivity to climate change, in the Chukchi Sea area than in the Eastern parts of the Arctic and subarctic regions, which are largely influenced by northern branches of the North Atlantic Drift. The climate sensitivity of the Chukchi Sea area may be related to the proximity of the Pacific gateway. Strong linkages between sea-surface conditions, sea ice cover and export rate seem tightly linked there with large scale atmospheric synopses in the North Pacific and possibly the tropical Pacific. The apparent consistency of the Mount Logan record (Fisher et al., the Holocene 2008) with those of the Chukchi Sea (de Vernal et al., Quat. Sci. Rev. 2013) tends to support the hypothesis of a strong influence of North Pacific atmospheric teleconnections on sea-surface conditions in the Western Arctic.

  13. Composition, buoyancy regulation and fate of ice algal aggregates in the Central Arctic Ocean.

    Directory of Open Access Journals (Sweden)

    Mar Fernández-Méndez

    Full Text Available Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen molar ratios of 8-35 and 9-40, respectively. Sub-ice algal aggregate densities ranged between 1 and 17 aggregates m(-2, maintaining an estimated net primary production of 0.4-40 mg C m(-2 d(-1, and accounted for 3-80% of total phototrophic biomass and up to 94% of local net primary production. A potential factor controlling the buoyancy of the aggregates was light intensity, regulating photosynthetic oxygen production and the amount of gas bubbles trapped within the mucous matrix, even at low ambient nutrient concentrations. Our data-set was used to evaluate the distribution and importance of Arctic algal aggregates as carbon source for pelagic and benthic communities.

  14. Composition, buoyancy regulation and fate of ice algal aggregates in the Central Arctic Ocean.

    Science.gov (United States)

    Fernández-Méndez, Mar; Wenzhöfer, Frank; Peeken, Ilka; Sørensen, Heidi L; Glud, Ronnie N; Boetius, Antje

    2014-01-01

    Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen molar ratios of 8-35 and 9-40, respectively. Sub-ice algal aggregate densities ranged between 1 and 17 aggregates m(-2), maintaining an estimated net primary production of 0.4-40 mg C m(-2) d(-1), and accounted for 3-80% of total phototrophic biomass and up to 94% of local net primary production. A potential factor controlling the buoyancy of the aggregates was light intensity, regulating photosynthetic oxygen production and the amount of gas bubbles trapped within the mucous matrix, even at low ambient nutrient concentrations. Our data-set was used to evaluate the distribution and importance of Arctic algal aggregates as carbon source for pelagic and benthic communities.

  15. The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves.

    Science.gov (United States)

    Zhang, Jinlun; Ashjian, Carin; Campbell, Robert; Hill, Victoria; Spitz, Yvette H; Steele, Michael

    2014-01-01

    [1] A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing

  16. Synthesis of integrated primary production in the Arctic Ocean: II. In situ and remotely sensed estimates

    Science.gov (United States)

    Hill, Victoria J.; Matrai, Patricia A.; Olson, Elise; Suttles, S.; Steele, Mike; Codispoti, L. A.; Zimmerman, Richard C.

    2013-03-01

    Recent warming of surface waters, accompanied by reduced ice thickness and extent may have significant consequences for climate-driven changes of primary production (PP) in the Arctic Ocean (AO). However, it has been difficult to obtain a robust benchmark estimate of pan-Arctic PP necessary for evaluating change. This paper provides an estimate of pan-Arctic PP prior to significant warming from a synthetic analysis of the ARCSS-PP database of in situ measurements collected from 1954 to 2007 and estimates derived from satellite-based observations from 1998 to 2007. Vertical profiles of in situ chlorophyll a (Chl a) and PP revealed persistent subsurface peaks in biomass and PP throughout the AO during most of the summer period. This was contradictory with the commonly assumed exponential decrease in PP with depth on which prior satellite-derived estimates were based. As remotely sensed Chl a was not a good predictor of integrated water column Chl a, accurate satellite-based modeling of vertically integrated primary production (IPPsat), requires knowledge of the subsurface distribution of phytoplankton, coincident with the remotely sensed ocean color measurements. We developed an alternative approach to modeling PP from satellite observations by incorporating climatological information on the depths of the euphotic zone and the mixed layer that control the distribution of phytoplankton that significantly improved the fidelity of satellite derived PP to in situ observations. The annual IPP of the Arctic Ocean combining both in situ and satellite based estimates was calculated here to be a minimum of 466 ± 94 Tg C yr-1 and a maximum of 993 ± 94 Tg C yr-1, when corrected for subsurface production. Inflow shelf seas account for 75% of annual IPP, while the central basin and Beaufort northern sea were the regions with the lowest annual integrated productivity, due to persistently stratified, oligotrophic and ice-covered conditions. Although the expansion of summertime

  17. Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

    Science.gov (United States)

    Monier, A.; Terrado, R.; Thaler, M.; Comeau, A.; Medrinal, E.; Lovejoy, C.

    2013-06-01

    The ubiquity of heterotrophic flagellates (HFL) in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8-20 μm cell diameter), mostly phagotrophic protists in the upper pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum layer, where light and nutrients are both available. This physically well-characterized system provided an opportunity to explore the community diversity of HFL from different water masses within the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada), targeting the surface, the subsurface chlorophyll maximum layer (SCM) and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1) to examine the possibility of niche differentiation within the stratified water column. Our results strongly suggested that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate-driven changes to the physical structure of the Arctic Ocean.

  18. Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

    Directory of Open Access Journals (Sweden)

    A. Monier

    2013-02-01

    Full Text Available The ubiquity of heterotrophic flagellates (HFL in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8–20 μm cell diameter, mostly phagotrophic protists in the pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum (SCM layer. This physically well-characterized system provided an opportunity to explore the community diversity of HFL across a wide region, and down the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada, targeting the surface, the SCM and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1 to examine the possibility of niche differentiation within the stratified water column. Our results strongly implied that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate driven changes to the physical structure of the Arctic Ocean.

  19. Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

    Directory of Open Access Journals (Sweden)

    A. Monier

    2013-06-01

    Full Text Available The ubiquity of heterotrophic flagellates (HFL in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8–20 μm cell diameter, mostly phagotrophic protists in the upper pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum layer, where light and nutrients are both available. This physically well-characterized system provided an opportunity to explore the community diversity of HFL from different water masses within the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada, targeting the surface, the subsurface chlorophyll maximum layer (SCM and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1 to examine the possibility of niche differentiation within the stratified water column. Our results strongly suggested that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate-driven changes to the physical structure of the Arctic Ocean.

  20. Annual Cycles of Multiyear Sea Ice Coverage of the Arctic Ocean: 1999-2003

    Science.gov (United States)

    Kwok, R.

    2004-01-01

    For the years 1999-2003, we estimate the time-varying perennial ice zone (PIZ) coverage and construct the annual cycles of multiyear (MY, including second year) ice coverage of the Arctic Ocean using QuikSCAT backscatter, MY fractions from RADARSAT, and the record of ice export from satellite passive microwave observations. An area balance approach extends the winter MY coverage from QuikSCAT to the remainder of the year. From these estimates, the coverage of MY ice at the beginning of each year is 3774 x 10(exp 3) sq km (2000), 3896 x 10(exp 3) sq km (2001), 4475 x 10(exp 3) sq km (2002), and 4122 x 10(exp 3) sq km (2003). Uncertainties in coverage are approx.150 x 10(exp 3) sq km. In the mean, on 1 January, MY ice covers approx.60% of the Arctic Ocean. Ice export reduces this coverage to approx.55% by 1 May. From the multiple annual cycles, the area of first-year (FY) ice that survives the intervening summers are 1192 x 10(exp 3) sq km (2000), 1509 x 10(exp 3) sq km (2001), and 582 x 10(exp 3) sq km (2002). In order for the MY coverage to remain constant from year to year, these replenishment areas must balance the overall area export and melt during the summer. The effect of the record minimum in Arctic sea ice area during the summer of 2002 is seen in the lowest area of surviving FY ice of the three summers. In addition to the spatial coverage, the location of the PIZ is important. One consequence of the unusual location of the PIZ at the end of the summer of 2002 is the preconditioning for enhanced export of MY ice into the Barents and Kara seas. Differences between the minimums in summer sea ice coverage from our estimates and passive microwave observations are discussed.

  1. Quaternary ostracode and foraminiferal biostratigraphy and paleoceanography in the western Arctic Ocean

    Science.gov (United States)

    Cronin, Thomas M.; DeNinno, Lauren H.; Polyak, L.V.; Caverly, Emma K.; Poore, Richard; Brenner, Alec R.; Rodriguez-Lazaro, J.; Marzen, R.E.

    2014-01-01

    The stratigraphic distributions of ostracodes and selected calcareous benthic and planktic foraminiferal species were studied in sediment cores from ~ 700 to 2700 m water depth on the Northwind, Mendeleev, and Lomonosov Ridges in the western Arctic Ocean. Microfaunal records in most cores cover mid- to late Quaternary sediments deposited in the last ~ 600 ka, with one record covering the last ~ 1.5 Ma. Results show a progressive faunal turnover during the mid-Pleistocene transition (MPT, ~ 1.2 to 0.7 Ma) and around the mid-Brunhes event (MBE, ~ 0.4 Ma) reflecting major changes in Arctic Ocean temperature, circulation and sea-ice cover. The observed MPT shift is characterized by the extinction of species that today inhabit the sea-ice free subpolar North Atlantic and/or seasonally sea-ice free Nordic Seas (Echinocythereis sp., Rockalliacf. enigmatica, Krithe cf. aquilonia, Pterygocythereis vannieuwenhuisei). After a very warm interglacial during marine isotope stage (MIS) 11 dominated by the temperate planktic foraminifer Turborotalita egelida, the MBE experienced a shift to polar assemblages characteristic of predominantly perennial Arctic sea-ice cover during the interglacial and interstadial periods of the last 300 ka. These include the planktic foraminifera Neogloboquadrina pachyderma, the sea-ice dwelling ostracodeAcetabulastoma arcticum and associated benthic taxa Pseudocythere caudata,Pedicythere neofluitans, and Polycope spp. Several species can be used as biostratigraphic markers of specific intervals such as ostracodes Rabilimis mirabilis — MIS 5 and P. vannieuwenhuisei extinction after MIS 11, and foraminiferal abundance zones Bulimina aculeata — late MIS 5 and Bolivina arctica — MIS 5-11.

  2. Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources

    Institute of Scientific and Technical Information of China (English)

    DONG Linsen; SHI Xuefa; LIU Yanguang; FANG Xisheng; CHEN Zhihua; WANG Chunjuan; ZOU Jianjun; HUANG Yuanhui

    2014-01-01

    Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. (1) Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. (2) Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands (Banks and Victoria). The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean.

  3. Mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean

    Science.gov (United States)

    Pnyushkov, A.; Polyakov, I.; Nguyen, A. T.

    2015-12-01

    Mesoscale eddies are an important component in Arctic Ocean dynamics and can play a role in vertical redistribution of ocean heat from the intermediate layer of warm Atlantic Water (AW). We analyze mooring data collected along the continental slope of the Laptev Sea in 2007-11 to improve the characterization of Arctic mesoscale eddies in this region of the Eurasian Basin (EB).Wavelet analyses suggest that ~20% of the mooring record is occupied by mesoscale eddies, whose vertical scales can be large, often >600 m. Based on similarity between temperature/salinity profiles measured inside eddies and modern climatology for the 2000s, we found two distinct sources of eddy formation in the EB; one in the vicinity of Fram Strait and the other at the continental slope of the Severnaya Zemlya Archipelago. Both sources of eddies are on the route of AW propagation along the EB margins, so that the Arctic Circumpolar Boundary Current (ACBC) can carry these eddies along the continental slope.The lateral advection of waters isolated inside the eddy cores by ACBC affect the heat and salt balance of the eastern EB. The average temperature anomaly inside Fram Strait eddies in the layer above the AW temperature core (i.e., above 350 m depth level) was ~0.1º C with the strongest temperature anomaly in this layer exceeding 0.5ºC. In contrast to Fram Strait eddies, Severnaya Zemlya eddies carry anomalously cold and fresh water, and likely contribute to ventilation of the AW core. In addition, we found increased vertical shears of the horizontal velocities inside eddies that result in enhanced mixing. Our estimates made using the Pacanowski and Philander (1981) relationship suggest that, on average, vertical diffusivity coefficients inside eddies are four times larger than those in the surrounding waters. We will use the high resolution ECCO model to investigate the relative contributions of along and across slope transports induced by eddies along the ACBC path.

  4. Quaternary history of sea ice in the western Arctic Ocean based on foraminifera

    Science.gov (United States)

    Polyak, Leonid; Best, Kelly M.; Crawford, Kevin A.; Council, Edward A.; St-Onge, Guillaume

    2013-11-01

    Sediment cores from the Northwind Ridge, western Arctic Ocean, including uniquely preserved calcareous microfossils, provide the first continuous proxy record of sea ice in the Arctic Ocean encompassing more than half of the Quaternary. The cores were investigated for foraminiferal assemblages along with coarse grain size and bulk chemical composition. By combination of glacial cycles and unique events reflected in the stratigraphy, the age of the foraminiferal record was estimated as ca 1.5 Ma. Foraminiferal abundances, diversity, and composition of benthic assemblages, especially phytodetritus and polar species, were used as proxies for sea-ice conditions. Foraminiferal Assemblage Zone 2 in the Lower Pleistocene indicates diminished, mostly seasonal sea ice, probably facilitated by enhanced inflow of Pacific waters. A gradual decrease in ice-free season with episodes of abrupt ice expansion is interpreted for the Mid-Pleistocene Transition, consistent with climatic cooling and ice-sheet growth in the Northern Hemisphere. A principal faunal and sedimentary turnover occurred near the Early-Middle Pleistocene boundary ca 0.75 Ma, with mostly perennial sea ice indicated by the overlying Assemblage Zone 1. Two steps of further increase in sea-ice coverage are inferred from foraminiferal assemblage changes in the "Glacial" Pleistocene by ca 0.4 and 0.24 Ma, possibly related to hemispheric (Mid-Brunhes Event) and Laurentide ice sheet growth, respectively. These results suggest that year-round ice in the western Arctic was a norm for the last several 100 ka, in contrast to rapidly disappearing summer ice today.

  5. Reconstructing Glacial Lake Vitim and its cataclysmic drainage to the Arctic Ocean

    Science.gov (United States)

    Margold, Martin; Jansen, John D.; Gurinov, Artem L.; Codilean, Alexandru T.; Preusser, Frank

    2013-04-01

    A large glacial lake (23500 km2/3000 km3) was formed when the River Vitim, one of the largest tributaries of the Lena River in Siberia, Russia, was blocked by glaciers from the Kodar Mountains. This lake, Glacial Lake Vitim, was subsequently drained in a large outburst flood that followed the rivers Vitim and Lena to the Arctic Ocean. Evidence of a cataclysmic drainage was first identified in the form of a large bedrock canyon in the area of the postulated ice dam. The enormous dimensions of this feature (6 x 2 x 0.3 km) suggest formation via a drainage event of extreme magnitude, and field inspection downstream revealed giant bars >100 m above the valley floor, similar to those described from cataclysmic floods elsewhere. We present chronological constraints for the duration of the ice dam and for the timing of the flood based on terrestrial cosmogenic nuclides and optically stimulated luminescence. Given that the volume of Glacial Lake Vitim was significantly larger than other well known lakes associated with cataclysmic outbursts-glacial lakes Missoula (northwestern USA) and Chuja-Kuray (Altai Mountains, Russia)-it is pertinent to assess the possible climatic consequences of Lake Vitim's drainage. The outburst flood from Glacial Lake Vitim is likely among the largest floods documented on Earth thus far. Possible impacts include rapid change of climate and precipitation patterns in the area of the former glacial lake, major disturbance along the flood course to the Arctic, and perhaps even regional-scale climatic feedbacks linked to altered sea ice dynamics in the Arctic Ocean.

  6. An early to mid-Pleistocene deep Arctic Ocean ostracode fauna with North Atlantic affinities

    Science.gov (United States)

    DeNinno, Lauren H.; Cronin, Thomas M.; Rodriquez-Lazaro, J.; Brenner, Alec R.

    2015-01-01

    An early to middle Pleistocene ostracode fauna was discovered in sediment core P1-93-AR-23 (P23, 76.95°N, 155.07°W) from 951 meter water depth from the Northwind Ridge, western Arctic Ocean. Piston core P23 yielded more than 30,000 specimens and a total of about 30 species. Several early to mid-Pleistocene species in the genera Krithe,Echinocythereis, Pterygocythereis, and Arcacythere are now extinct in the Arctic and show taxonomic affinities to North Atlantic Ocean species. Our results suggest that there was a major ostracode faunal turnover during the global climate transitions known as the Mid-Pleistocene Transition (MPT, ~ 1.2 to 0.7 Ma) and the Mid-Brunhes Event (MBE, ~ 400 ka) reflecting the development of perennial sea ice during interglacial periods and large ice shelves during glacial periods over the last 400,000 years.

  7. Radiation of lamp and optimized experiment using artificial light in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jin-ping; David Barber; LI Tao; LI Shu-jiang; LI Xiang

    2008-01-01

    A winter optical experiment by an artificial lamp was conducted in the Amundsen Bay of Arctic Ocean from November of 2007 to January of 2008. The radiation field emitted from an artificial lamp was measured and is introduced in this paper, and the optimized experiment project is discussed. It is demonstrated that the minimum size allowed of the lamp is determined by both the field of view (FOV) of optical instrument and the measuring distance from the lamp. Some problems that might influence on the experiment result often occur for a simple fluorescent lamp,such as instability, spatial nonuniformity, light divergence, effect of lamp temperature, etc. By the analysis of the light radiation, three kind of measures are proposed to control the quality of the experiment, i.e. keeping consistency of lamp size with FOV of instrument, calibrating in situ downwind, and conducting measurement in effective range. Among them, the downwind calibration is the key step to overcome most problems arose by the lamp. The experiment indicated that the reliable results can be obtained only when the optical measurement is coordinated with the radiation field of artificial lamp. The measured radiation property of the lamp was used to advise the field experiment to minimize measuring error. As the experiment by artificial lamp was the first attempt in the Arctic Ocean, the experience given by this paper is a valuable reference to the correlative studies.

  8. Sea-ice freeboard heights in the Arctic Ocean from ICESat and airborne lidar - a comparison

    Science.gov (United States)

    Skourup, H.; Forsberg, R.

    2005-12-01

    Two near-coincident tracks of ICESat/GLAS and airborne scanning airborne lidar data were acquired on May 25, 2004, in the Arctic Ocean north of Greenland, in an area of thick perennial sea-ice with few open leads and numerous large ridges. The airborne lidar data, having a relative accuracy of few cm and 1 m spatial resolution, provide an excellent quantification of the ability of ICESat to detect and model sea-ice features such as leads and ridges, as well as gaining insight into the expected ICESat waveforms over heavily deformed sea-ice. In the paper we outline the underflight experiment and hardware, as well as show examples of the good fit between ICESat and filtered airborne data, matching the ICESat footprint. We also compare the observed ICESat waveforms to the airborne data, as well as quantify the biases induced by "lowest-level" filtering techniques in this particular area. We conclude by showing examples of Arctic Ocean-wide freeboard heights derived from ICESat by an improved "lowest-level" technique, showing good overall correlation to Quikscat multi-year ice distribution and expected seasonal changes.

  9. An examination of double-diffusive processes in a mesoscale eddy in the Arctic Ocean

    Science.gov (United States)

    Bebieva, Yana; Timmermans, Mary-Louise

    2016-01-01

    Temperature and salinity measurements of an Atlantic Water mesoscale eddy in the Arctic Ocean's Canada Basin are analyzed to understand the effects of velocity shear on a range of double-diffusive processes. Double-diffusive structures in and around the eddy are examined through the transition from low shear (outside the eddy and within its solid body core) to high geostrophic shear zones at the eddy flanks. The geostrophic Richardson number takes large values where a double-diffusive staircase is observed and lowest values at the eddy flanks where geostrophic velocity is largest and a well-formed staircase is not present. A Thorpe scale analysis is used to estimate turbulent diffusivities in the flank regions. Double-diffusive and turbulent heat, salt, and buoyancy fluxes from the eddy are computed, and used to infer that the eddy decays on time scales of around 4-9 years. Fluxes highlight that Atlantic Water heat within the eddy can be fluxed downward into deeper water layers by means of both double-diffusive and turbulent mixing. Estimated lateral variations in vertical fluxes across the eddy allow for speculation that double diffusion speeds up the eddy decay, having important implications for the transfer of Atlantic Water heat in the Arctic Ocean.

  10. Central Arctic Ocean freshwater during a period of anomalous melt and advection in 2015

    Science.gov (United States)

    Rabe, Benjamin; Korhonen, Meri; Hoppmann, Mario; Ricker, Robert; Hendricks, Stefan; Krumpen, Thomas; Beckers, Justin; Schauer, Ursula

    2016-04-01

    During the recent decade the Arctic Ocean has shown several years of very low sea-ice extent and an increase in liquid freshwater. Yet, the processes underlying the interannual variability are still not fully understood. Hydrographic observations by ship campaigns and autonomous platforms reveal that summer 2015 showed above average liquid freshwater in the upper ocean of the central Arctic. Surface temperatures and sea level pressure were also higher than the average of the preceeding two decades. From hydrographic observations and atmospheric reanalysis data we show that this liquid freshwater anomaly is associated with above average sea-ice melt and intensified northward Ekman transport. We, further, found significant amounts of Pacific Water in the upper water column, from the mixed-layer to the upper halocline. Our results suggest that the freshening was due to both advection of low-salinity water from the direction of the Siberian shelves, the Beaufort Gyre and the Bering Strait, and enhance sea-ice melt.

  11. Evidence for ice-free summers in the late Miocene central Arctic Ocean

    Science.gov (United States)

    Stein, Ruediger; Fahl, Kirsten; Schreck, Michael; Knorr, Gregor; Niessen, Frank; Forwick, Matthias; Gebhardt, Catalina; Jensen, Laura; Kaminski, Michael; Kopf, Achim; Matthiessen, Jens; Jokat, Wilfried; Lohmann, Gerrit

    2016-01-01

    Although the permanently to seasonally ice-covered Arctic Ocean is a unique and sensitive component in the Earth's climate system, the knowledge of its long-term climate history remains very limited due to the restricted number of pre-Quaternary sedimentary records. During Polarstern Expedition PS87/2014, we discovered multiple submarine landslides along Lomonosov Ridge. Removal of younger sediments from steep headwalls has led to exhumation of Miocene sediments close to the seafloor. Here we document the presence of IP25 as a proxy for spring sea-ice cover and alkenone-based summer sea-surface temperatures >4 °C that support a seasonal sea-ice cover with an ice-free summer season being predominant during the late Miocene in the central Arctic Ocean. A comparison of our proxy data with Miocene climate simulations seems to favour either relatively high late Miocene atmospheric CO2 concentrations and/or a weak sensitivity of the model to simulate the magnitude of high-latitude warming in a warmer than modern climate. PMID:27041737

  12. Modeling the impact of riverine DON removal by marine bacterioplankton on primary production in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    V. Le Fouest

    2014-12-01

    Full Text Available The planktonic and biogeochemical dynamics of the Arctic shelves exhibit a strong variability in response to Arctic warming. In this study, in order to elucidate on the processes regulating the production of phytoplankton (PP and bacterioplankton (BP and their interactions, we employ a biogeochemical model coupled to a pan-Arctic ocean-sea ice model (MITgcm to explicitly simulate and quantify the contribution of usable dissolved organic nitrogen (DON drained by the major circum-Arctic rivers on PP and BP in a scenario of melting sea ice (1998–2011. Model simulations suggest that on average between 1998 and 2011, the removal of usable RDON by bacterioplankton is responsible of a ~26% increase of the annual BP for the whole Arctic Ocean. With respect to total PP, the model simulates an increase of ~8% on an annual basis and of ~18% in summer. Recycled ammonium is responsible for the PP increase. The recycling of RDON by bacterioplankton promotes higher BP and PP but there is no significant temporal trend in the BP : PP ratio within the ice-free shelves over the 1998–2011 period. This suggests no significant evolution in the balance between autotrophy and heterotrophy in the last decade with a constant annual flux of RDON into the coastal ocean although changes in RDON supply and further reduction in sea ice cover could potentially alter this delicate balance.

  13. Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period

    Science.gov (United States)

    Kobayashi, Daisuke; Yamamoto, Masanobu; Irino, Tomohisa; Nam, Seung-Il; Park, Yu-Hyeon; Harada, Naomi; Nagashima, Kana; Chikita, Kazuhisa; Saitoh, Sei-Ichi

    2016-12-01

    This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*-b* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite + kaolinite)/illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.

  14. Jurassic to Present Evolution of the Arctic Ocean Region: Questions for IPY

    Science.gov (United States)

    Lawver, L. L.; Gahagan, L. M.; Childers, V. A.; Brozena, J. M.; Grantz, A.

    2007-12-01

    In 1955, Carey first suggested a rotational opening of the Arctic Ocean based on his theories concerning oroclinal bending. It was only with the plate tectonic revolution in the next decade that there were a number of seminal abstracts and papers concerning the tectonic evolution of the Canada Basin. Grantz in 1966, Hamilton in 1967 and Tailleur in 1969 formulated the idea that the Canada Basin may have opened about a pivot point in the Mackenzie Delta. In 1968, Karasik first published his revolutionary idea that aeromagnetic anomalies collected over the Gakkel Ridge in the Eurasian Basin suggested that seafloor spreading during the Tertiary accounted for most of the oceanic crust between the Lomonosov Ridge and the Barents and Kara shelves. From the results of the 1979 Lomonosov Ridge experiment by Forsyth and Mair, it was established that the deep crustal velocities of the Lomonosov Ridge are remarkably similar to those of the Kara Sea shelf at 82°N, making it a continental sliver that rifted off the Barents and Kara Sea shelves. Consequently, the Arctic Ocean can be divided into a mostly Tertiary to present Eurasian Basin, and the older Mesozoic Amerasian Basin. Even with additional data from the Amerasian Basin including extensive airborne, ship-based, and satellite magnetics and gravity, the tectonic evolution of the Canada and Makarov components of the Amerasian Basin are still controversial. While the final phase of opening of the Amerasian Basin may have been rotational about a pivot point near or south of the Mackenzie Delta, the earlier phases and even the directions of the initial basin formation are still in doubt. Vogt and others first suggested a possible hotspot origin for the Alpha and Mendeleev Ridges and related them to the Iceland hotspot. Age versus depth and heat flow versus depth give a tentative age for the Amerasian Basin of latest Jurassic to early Cretaceous with seafloor spreading ending prior to the beginning of the Cretaceous Normal

  15. Comparison between summertime and wintertime Arctic Ocean primary marine aerosol properties

    Directory of Open Access Journals (Sweden)

    J. Zábori

    2013-05-01

    Full Text Available Primary marine aerosols (PMAs are an important source of cloud condensation nuclei, and one of the key elements of the remote marine radiative budget. Changes occurring in the rapidly warming Arctic, most importantly the decreasing sea ice extent, will alter PMA production and hence the Arctic climate through a set of feedback processes. In light of this, laboratory experiments with Arctic Ocean water during both Arctic winter and summer were conducted and focused on PMA emissions as a function of season and water properties. Total particle number concentrations and particle number size distributions were used to characterize the PMA population. A comprehensive data set from the Arctic summer and winter showed a decrease in PMA concentrations for the covered water temperature (Tw range between −1°C and 15°C. A sharp decrease in PMA emissions for a Tw increase from −1°C to 4°C was followed by a lower rate of change in PMA emissions for Tw up to about 6°C. Near constant number concentrations for water temperatures between 6°C to 10°C and higher were recorded. Even though the total particle number concentration changes for overlapping Tw ranges were consistent between the summer and winter measurements, the distribution of particle number concentrations among the different sizes varied between the seasons. Median particle number concentrations for a dry diameter (DpDp > 0.125μm, the particle number concentrations during winter were mostly higher than in summer (up to 50%. The normalized particle number size distribution as a function of water temperature was examined for both winter and summer measurements. An increase in Tw from −1°C to 10°C during winter measurements showed a decrease in the peak of relative particle number concentration at about a Dp of 0.180μm, while an increase was observed for particles with Dp > 1μm. Summer measurements exhibited a relative shift to smaller particle sizes for an increase of Tw in the range

  16. Diversity of cultured photosynthetic flagellates in the northeast Pacific and Arctic Oceans in summer

    Directory of Open Access Journals (Sweden)

    S. Balzano

    2012-11-01

    Full Text Available During the MALINA cruise (summer 2009, an extensive effort was undertaken to isolate phytoplankton strains from the northeast (NE Pacific Ocean, the Bering Strait, the Chukchi Sea, and the Beaufort Sea. In order to characterise the main photosynthetic microorganisms occurring in the Arctic during the summer season, strains were isolated by flow cytometry sorting (FCS and single cell pipetting before or after phytoplankton enrichment of seawater samples. Strains were isolated both onboard and back in the laboratory and cultured at 4 °C under light/dark conditions. Overall, we isolated and characterised by light microscopy and 18 S rRNA gene sequencing 104 strains of photosynthetic flagellates which grouped into 21 genotypes (defined by 99.5% 18 S rRNA gene sequence similarity, mainly affiliated to Chlorophyta and Heterokontophyta. The taxon most frequently isolated was an Arctic ecotype of the green algal genus Micromonas (Arctic Micromonas, which was nearly the only phytoplankter recovered within the picoplankton (< 2 μm size range. Strains of Arctic Micromonas as well as other strains from the same class (Mamiellophyceae were identified in further detail by sequencing the internal transcribed spacer (ITS region of the rRNA operon. The MALINA Micromonas strains share identical 18 S rRNA and ITS sequences suggesting high genetic homogeneity within Arctic Micromonas. Three other Mamiellophyceae strains likely belong to a new genus. Other green algae from the genera Nephroselmis, Chlamydomonas, and Pyramimonas were also isolated, whereas Heterokontophyta included some unidentified Pelagophyceae, Dictyochophyceae (Pedinellales, and Chrysophyceae (Dinobryon faculiferum. Moreover, we isolated some Cryptophyceae (Rhodomonas sp. as well as a few Prymnesiophyceae and dinoflagellates. We identified the dinoflagellate Woloszynskia cincta by scanning electron microscopy (SEM and 28 S r

  17. Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic

    Science.gov (United States)

    Hu, Q.; Xie, Z.; Wang, X.; Kang, H.; Zhang, P.

    2015-12-01

    Biomass burning discharges numerous kinds of gases and aerosols, such as carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), black carbon (BC), alcohols, organic acids and persistent organic pollutants (POPs), and is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we measure levoglucosan, a superior molecular tracer of biomass burning aerosols because of its single source, in marine air from the Arctic Ocean through the North and South Pacific Ocean to coastal Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m3 levels. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Marine air in the mid-latitudes (30°-60° N and S) has the highest levoglucosan loading due to the emission from adjacent lands. Air over the Arctic Ocean which affected by biomass burning in the east Siberia has intermediate loading. Equatorial latitudes is the main source of biomass burning emissions, however, levoglucosan is in relatively low level. Large amount of precipitation and high hydroxyl radical concentration in this region cause more deposition and degradation of levoglucosan during transport. Previous studies were debatable on the influence of biomass burning on the Antarctic because of uncertain source of BC. Here via levoglucosan, it is proved that although far away from emission sources, the Antarctic is still affected by biomass burning aerosols which may be derived from South America. Biomass burning has a significant impact on mercury (Hg) and water-soluble organic carbon (WSOC) in marine aerosols from pole to pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere.

  18. Modeling ocean and sea ice dynamics of the Canadian Arctic Archipelago: Aspects of forcing

    Science.gov (United States)

    Wekerle, Claudia; Wang, Qiang; Danilov, Sergey; Myers, Paul G.; Jung, Thomas; Schröter, Jens

    2013-04-01

    The Canadian Arctic Archipelago (CAA) is one of the main pathways for freshwater exiting the Arctic Ocean. Freshwater exported to the North Atlantic may influence the deep water formation in the Labrador Sea, and thus the meridional overturning circulation. Modeling ocean and sea ice conditions of the CAA is difficult because of narrow straits and complex coastlines. The Finite-Element Sea-ice Ocean circulation Model (FESOM) configured on a global mesh is applied to assess the volume, freshwater and sea ice transports through the CAA. With a mesh resolution of 5 km in the CAA we are able to accurately resolve complex coastlines. Outside the CAA the mesh is refined to 24 km north of 55°N with a global background resolution of 1.5°. In this study, first, it is shown that the transports modeled with FESOM correlate well with the available observational data. Second, the model is used to learn about the impact of different atmospheric forcing datasets differing in spatial and temporal resolution (CORE 2 and the Reforecast dataset from Environment Canada). The CORE 2 dataset is on the T62 grid, which is coarse compared to the Reforecast dataset with grid resolution of 0.45° longitude and 0.3° latitude. The temporal resolution of the Reforecast dataset is higher than the CORE 2 dataset (one hourly and 6-hourly data, respectively, for wind, surface temperature and specific humidity fields). The representation of sea ice in the CAA can be improved by using the high resolution atmospheric forcing.

  19. Regional variations in provenance and abundance of ice-rafted clasts in Arctic Ocean sediments: Implications for the configuration of late Quaternary oceanic and atmospheric circulation in the Arctic

    Science.gov (United States)

    Phillips, R.L.; Grantz, A.

    2001-01-01

    The composition and distribution of ice-rafted glacial erratics in late Quaternary sediments define the major current systems of the Arctic Ocean and identify two distinct continental sources for the erratics. In the southern Amerasia basin up to 70% of the erratics are dolostones and limestones (the Amerasia suite) that originated in the carbonate-rich Paleozoic terranes of the Canadian Arctic Islands. These clasts reached the Arctic Ocean in glaciers and were ice-rafted to the core sites in the clockwise Beaufort Gyre. The concentration of erratics decreases northward by 98% along the trend of the gyre from southeastern Canada basin to Makarov basin. The concentration of erratics then triples across the Makarov basin flank of Lomonosov Ridge and siltstone, sandstone and siliceous clasts become dominant in cores from the ridge and the Eurasia basin (the Eurasia suite). The bedrock source for the siltstone and sandstone clasts is uncertain, but bedrock distribution and the distribution of glaciation in northern Eurasia suggest the Taymyr Peninsula-Kara Sea regions. The pattern of clast distribution in the Arctic Ocean sediments and the sharp northward decrease in concentration of clasts of Canadian Arctic Island provenance in the Amerasia basin support the conclusion that the modem circulation pattern of the Arctic Ocean, with the Beaufort Gyre dominant in the Amerasia basin and the Transpolar drift dominant in the Eurasia basin, has controlled both sea-ice and glacial iceberg drift in the Arctic Ocean during interglacial intervals since at least the late Pleistocene. The abruptness of the change in both clast composition and concentration on the Makarov basin flank of Lomonosov Ridge also suggests that the boundary between the Beaufort Gyre and the Transpolar Drift has been relatively stable during interglacials since that time. Because the Beaufort Gyre is wind-driven our data, in conjunction with the westerly directed orientation of sand dunes that formed during

  20. Net primary productivity estimates and environmental variables in the Arctic Ocean: An assessment of coupled physical-biogeochemical models

    Science.gov (United States)

    Lee, Younjoo J.; Matrai, Patricia A.; Friedrichs, Marjorie A. M.; Saba, Vincent S.; Aumont, Olivier; Babin, Marcel; Buitenhuis, Erik T.; Chevallier, Matthieu; de Mora, Lee; Dessert, Morgane; Dunne, John P.; Ellingsen, Ingrid H.; Feldman, Doron; Frouin, Robert; Gehlen, Marion; Gorgues, Thomas; Ilyina, Tatiana; Jin, Meibing; John, Jasmin G.; Lawrence, Jon; Manizza, Manfredi; Menkes, Christophe E.; Perruche, Coralie; Le Fouest, Vincent; Popova, Ekaterina E.; Romanou, Anastasia; Samuelsen, Annette; Schwinger, Jörg; Séférian, Roland; Stock, Charles A.; Tjiputra, Jerry; Tremblay, L. Bruno; Ueyoshi, Kyozo; Vichi, Marcello; Yool, Andrew; Zhang, Jinlun

    2016-12-01

    The relative skill of 21 regional and global biogeochemical models was assessed in terms of how well the models reproduced observed net primary productivity (NPP) and environmental variables such as nitrate concentration (NO3), mixed layer depth (MLD), euphotic layer depth (Zeu), and sea ice concentration, by comparing results against a newly updated, quality-controlled in situ NPP database for the Arctic Ocean (1959-2011). The models broadly captured the spatial features of integrated NPP (iNPP) on a pan-Arctic scale. Most models underestimated iNPP by varying degrees in spite of overestimating surface NO3, MLD, and Zeu throughout the regions. Among the models, iNPP exhibited little difference over sea ice condition (ice-free versus ice-influenced) and bottom depth (shelf versus deep ocean). The models performed relatively well for the most recent decade and toward the end of Arctic summer. In the Barents and Greenland Seas, regional model skill of surface NO3 was best associated with how well MLD was reproduced. Regionally, iNPP was relatively well simulated in the Beaufort Sea and the central Arctic Basin, where in situ NPP is low and nutrients are mostly depleted. Models performed less well at simulating iNPP in the Greenland and Chukchi Seas, despite the higher model skill in MLD and sea ice concentration, respectively. iNPP model skill was constrained by different factors in different Arctic Ocean regions. Our study suggests that better parameterization of biological and ecological microbial rates (phytoplankton growth and zooplankton grazing) are needed for improved Arctic Ocean biogeochemical modeling.

  1. Atmospheric winter conditions 2007/08 over the Arctic Ocean based on NP-35 data and regional model simulations

    Directory of Open Access Journals (Sweden)

    M. Mielke

    2014-05-01

    Full Text Available Atmospheric measurements on the drifting Arctic sea ice station "North Pole-35" crossing the Eastern part of the Arctic Ocean during winter 2007/2008 have been compared with regional atmospheric HIRHAM model simulations. The observed near-surface temperature, mean sea level pressure and the vertical temperature, wind and humidity profiles are satisfactorily reproduced by the model. The strongest temperature differences between observations and the simulations occur near the surface due to an overestimated vertical mixing of heat in the stable Arctic boundary layer (ABL. The observations show very strong temperature inversions near the surface, whereas the simulated inversions occur frequently between the surface and 415 m at too high levels. The simulations are not able to reproduce the observed inversion strength. The regional model underestimates the wind speeds and the sharp vertical wind gradients. The strength of internal atmospheric dynamics on the temporal development of atmospheric surface variables and vertical profiles of temperature, wind and relative humidity has been examined. Although the HIRHAM model systematically overestimates relative humidity and produces too high long-wave downward radiation during winter, two different atmospheric circulation states, which are connected to higher or lower pressure systems over the Eastern part of the Arctic Ocean, are simulated in agreement with the NP-35 observations. Sensitivity studies with reduced vertical mixing of heat in the stable ABL have been carried out. A slower increase in the stability functions with decreasing Richardson number under stable stratification has an impact on the horizontal and vertical atmospheric structure. Changes in synoptical cyclones on time scales from 1–3 days over the North Atlantic cyclone path are generated, which influences the atmospheric baroclinic and planetary waves on time scales up to 20 days over the Arctic Ocean basin. The use of increased

  2. A new aeromagnetic survey of the North Pole and the Arctic Ocean north of Greenland and Ellesmere Island

    DEFF Research Database (Denmark)

    Matzka, Jürgen; Rasmussen, Thorkild M.; Olesen, Arne Vestergaard

    2010-01-01

    We present a preliminary analysis of more than 50,000 km of aeromagnetic survey lines flown in the Arctic Ocean, acquired in 2009 with an optically pumped scalar magnetometer as part of the airborne geophysical survey ‘LOMGRAV’. From the observations we removed main and magnetospheric fields as g...

  3. Sailing the Open Polar Sea...Again: What Are You Teaching Your Children about the Arctic Ocean?

    Science.gov (United States)

    Stockard, James W. Jr.

    1989-01-01

    Relates how a blunder about the Arctic Ocean and the polar ice cap made by the author in his first year of teaching led to a successful learning experience. Lists five important discussion topics that social studies teachers should use to teach about this remote, but strategic, part of the world. (LS)

  4. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    Science.gov (United States)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  5. Reconstruction of the Arctic Ocean environment during the Eocene Azolla interval using geochemical proxies and climate modeling. Geologica Ultraiectina (331)

    NARCIS (Netherlands)

    Speelman, E.N.

    2010-01-01

    With the realization that the Arctic Ocean was covered with enormous quantities of the aquatic floating fern Azolla 49 Myrs ago, new questions regarding the Eocene conditions facilitating these blooms arose. This dissertation describes the reconstruction of paleo-environmental conditions facilitatin

  6. Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer wat

  7. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer wat

  8. Productivity, chlorophyll a, Photosynthetically Active Radiation (PAR) and other phytoplankton data from the Arctic Ocean, Bering Sea, Chukchi Sea, Beaufort Sea, East Siberian Sea, Kara Sea, Barents Sea, and Arctic Archipelago measured between 17 April, 1954 and 30 May, 2006 compiled as part of the Arctic System Science Primary Production (ARCSS-PP) observational synthesis project (NODC Accession 0063065)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Arctic Ocean primary production data were assembled from original input data archived in various international databases, provided by individual investigators or in...

  9. Effective Elastic Thickness of Southeast Part of Arctic Ocean-Eurasia Continent-Pacific Ocean Geoscience Transect

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effective lithospheric elastic thickness of the continent is an important parameter for examination of the large-scale structure and analyses of the mechanism of isostatic compensation within the plate, and a parameter standing for the strength of the lithosphere. The Te values along QuanzhouHeishui, the southeast section of the Arctic Ocean-Eurasian Continent-Pacific Ocean geoscience transect,are estimated by using the coherence technique developed by Forsyth. Studies of the feature of the coherence between gravity and topography suggest that at short wavelengths (6.6-100 km) for each data box that is used to estimate Te, the plate is strong enough to support topographic loads and gravity and topography are uncorrelated. At long wavelengths where the plate is deflected by surface and subsurface loads are compensated by the flexure model. Sichuan land-stone with Iow heat-flow values has high Te values whereas in Ninghua, Datian, land-stone with high heat-flow values has low To values, which reflects a correlation, iow heat-flow values corresponding to high Te values and high heat-flow values corresponding to low Te values. Te values can be divided into two sections: northwest high section and southeast iow section. There is roughly a positive correlation between crustal thickness and effective elastic thickness of the lithosphere.

  10. Diagenetic regimes in Arctic Ocean sediments: Implications for sediment geochemistry and core correlation

    Science.gov (United States)

    Meinhardt, A.-K.; März, C.; Schuth, S.; Lettmann, K. A.; Schnetger, B.; Wolff, J.-O.; Brumsack, H.-J.

    2016-09-01

    Dark brown sediment layers are a potential stratigraphic tool in Quaternary Arctic Ocean sediments. They are rich in Mn, Fe, and trace metals scavenged from the water column and were most likely deposited during interglacial intervals. In this study, we combine sediment and pore water data from sediment cores taken in different parts of the Arctic Ocean to investigate the influence of early diagenetic processes on sediment geochemistry. In most studied cores, Mn, Co, and Mo are released into the pore waters from Mn oxide dissolution in deeper (>1.5 m) sediment layers. The relationship between sedimentary Mn, Co, and Mo contents in excess of the lithogenic background (elementxs) shows that Coxs/Moxs values are a diagnostic tool to distinguish between layers with diagenetic metal addition from the pore waters (Coxs/Moxs 10), and unaffected layers (Coxs/Moxs from 1 to 10). Steady-state calculations based on current pore water profiles reveal that in the studied cores, the diagenetic addition of these metals from the pore water pool alone is not sufficient to produce the sedimentary metal enrichments. However, it seems evident that dissolution of Mn oxides in the Mn reduction zone can permanently alter the primary geochemical signature of the dark brown layers. Therefore, pore water data and Coxs/Moxs values should be considered before core correlation when this correlation is solely based on Mn contents and dark sediment color. In contrast to the mostly non-lithogenic origin of Mn in the dark brown layers, sedimentary Fe consists of a large lithogenic (80%) and a small non-lithogenic fraction (20%). Our pore water data show that diagenetic Fe remobilization is not currently occurring in the sediment. The dominant Fe sources are coastal erosion and river input. Budget calculations show that Fe seems to be trapped in the modern Arctic Ocean and accumulates in shelf and basin sediments. The Fe isotopic signal δ56Fe of the solid phase is positive (∼0.2-0.3‰) in

  11. The Open-Ocean Sensible Heat Flux and Its Significance for Arctic Boundary Layer Mixing During Early Fall

    Science.gov (United States)

    Ganeshan, Manisha; Wu, Dongliang

    2016-01-01

    The increasing ice-free area during late summer has transformed the Arctic to a climate system with more dynamic boundary layer (BL) clouds and seasonal sea ice growth. The open-ocean sensible heat flux, a crucial mechanism of excessive ocean heat loss to the atmosphere during the fall freeze season, is speculated to play an important role in the recently observed cloud cover increase and BL instability. However, lack of observations and understanding of the resilience of the proposed mechanisms, especially in relation to meteorological and interannual variability, has left a poorly constrained BL parameterization scheme in Arctic climate models. In this study, we use multiyear Japanese cruise-ship observations from RV Mirai over the open Arctic Ocean to characterize the surface sensible heat flux (SSHF) during early fall and investigate its contribution to BL turbulence. It is found that mixing by SSHF is favored during episodes of high surface wind speed and is also influenced by the prevailing cloud regime. The deepest BLs and maximum ocean-atmosphere temperature difference are observed during cold air advection (associated with the stratocumulus regime), yet, contrary to previous speculation, the efficiency of sensible heat exchange is low. On the other hand, the SSHF contributes significantly to BL mixing during the uplift (low pressure) followed by the highly stable (stratus) regime. Overall, it can explain 10 of the open ocean BL height variability, whereas cloud-driven (moisture and radiative) mechanisms appear to be the other dominant source of convective turbulence. Nevertheless, there is strong interannual variability in the relationship between the SSHF and the BL height which can be intensified by the changing occurrence of Arctic climate patterns, such as positive surface wind speed anomalies and more frequent conditions of uplift. This study highlights the need for comprehensive BL observations like the RV Mirai for better understanding and

  12. The open-ocean sensible heat flux and its significance for Arctic boundary layer mixing during early fall

    Science.gov (United States)

    Ganeshan, Manisha; Wu, Dong L.

    2016-10-01

    The increasing ice-free area during late summer has transformed the Arctic to a climate system with more dynamic boundary layer (BL) clouds and seasonal sea ice growth. The open-ocean sensible heat flux, a crucial mechanism of excessive ocean heat loss to the atmosphere during the fall freeze season, is speculated to play an important role in the recently observed cloud cover increase and BL instability. However, lack of observations and understanding of the resilience of the proposed mechanisms, especially in relation to meteorological and interannual variability, has left a poorly constrained BL parameterization scheme in Arctic climate models. In this study, we use multi-year Japanese cruise-ship observations from R/V Mirai over the open Arctic Ocean to characterize the surface sensible heat flux (SSHF) during early fall and investigate its contribution to BL turbulence. It is found that mixing by SSHF is favored during episodes of high surface wind speed and is also influenced by the prevailing cloud regime. The deepest BLs and maximum ocean-atmosphere temperature difference are observed during cold air advection (associated with the stratocumulus regime), yet, contrary to previous speculation, the efficiency of sensible heat exchange is low. On the other hand, the SSHF contributes significantly to BL mixing during the uplift (low pressure) followed by the highly stable (stratus) regime. Overall, it can explain ˜ 10 % of the open-ocean BL height variability, whereas cloud-driven (moisture and radiative) mechanisms appear to be the other dominant source of convective turbulence. Nevertheless, there is strong interannual variability in the relationship between the SSHF and the BL height which can be intensified by the changing occurrence of Arctic climate patterns, such as positive surface wind speed anomalies and more frequent conditions of uplift. This study highlights the need for comprehensive BL observations like the R/V Mirai for better understanding and

  13. Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian basin surface waters are undersaturated with respect to aragonite.

    Directory of Open Access Journals (Sweden)

    Lisa L Robbins

    Full Text Available Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index for the western Arctic Ocean. This data set documents aragonite undersaturation in ≈ 20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean's largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

  14. Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian basin surface waters are undersaturated with respect to aragonite.

    Science.gov (United States)

    Robbins, Lisa L; Wynn, Jonathan G; Lisle, John T; Yates, Kimberly K; Knorr, Paul O; Byrne, Robert H; Liu, Xuewu; Patsavas, Mark C; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ≈ 20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean's largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

  15. Low-level jet characteristics over the Arctic Ocean in spring and summer

    Directory of Open Access Journals (Sweden)

    L. Jakobson

    2013-01-01

    Full Text Available Low-level jets (LLJ are important for turbulence in the stably stratified atmospheric boundary layer, but their occurrence, properties, and generation mechanisms in the Arctic are not well known. We analysed LLJs over the central Arctic Ocean in spring and summer 2007 on the bases of data collected in the drifting ice station Tara. Instead of traditional radiosonde soundings, data from tethersonde soundings with a high vertical resolution were used. The Tara results showed a lower occurrence of LLJs (46% than many previous studies over polar sea ice. Strong jet core winds contributed to growth of the turbulent layer. Complex relationship between the jet core height and the temperature inversion top height were detected: substantial correlation (r = 0.72; p < 0.01 occurred when the jet core was above the turbulent layer, but inside the turbulent layer there was no correlation. The most important forcing mechanism for LLJs was baroclinicity, which was responsible for generation of strong and warm LLJs, which on average occurred at lower altitudes than other jets. Baroclinic jets were mostly associated to transient cyclones instead of the climatological air temperature gradients. Besides baroclinicity, cases related to inertial oscillations, gusts, and fronts were detected. In approximately 50% of the observed LLJs the generation mechanism remained unclear, but in most of these cases the wind speed was strong in the whole vertical profile, the jet core representing only a weak maximum. Further research needs on LLJs in the Arctic include investigation of low-level jet streams and their effects on the sea ice drift and atmospheric moisture transport.

  16. Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Y. Shen

    2012-12-01

    Full Text Available Dissolved organic carbon (DOC and total dissolved amino acids (TDAA were measured in high (Chukchi Sea and low (Beaufort Sea productivity regions of the western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM. Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High concentrations and yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Concentrations and yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05 in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001 in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi Sea implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the central Arctic basins.

  17. Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Y. Shen

    2012-07-01

    Full Text Available Dissolved organic carbon (DOC and total dissolved amino acids (TDAA were measured in high (Chukchi Sea and low (Beaufort Sea productivity regions of the Western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM. Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05 in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001 in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the Western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the Central Arctic basins.

  18. The Hydromedusae and its distribution in Chukchi Sea and adjacent southern edge waters of Canada Basin, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    张金标; 林茂

    2001-01-01

    The present paper is based on materials collected in Chukchi Sea and adjacent southern edge waters of Canada Basin, Arctic Ocean during the period from July to August 1999 on the icebreaker, the R/V “Xuelong”, by the Chinese First Arctic Scientific Expedition. Totally, 8 species of pelagic Hydromedusae were identified, of which 4 species belonged to Anthomedusae, 2 species to Leptomedusae, 1 species to Trachymedusae and 1 species to Narcomedusae, the Neoturris breviconis is recorded for the first time in Chukchi Sea. Their principal morphological characteristics are described and illustrated. The 8 species of Hydromedusae occurring in the Chukchi Sea were all cold water species, of which 6 species belong to neritic species and 2 species to ocean species. According to the geographic distribution of species, they may be divided into three groups: Arctic species, Arctic-boreal species and Boreal-temperate species. From the view-point of zoogeography, species from these waters belong to the Arctic fauna.The abundance of Hydromedusae in Chukchi Sea was generally low, with a mean value of 108 ind.*10-2*m-3. Rathkea octopunctata and Aglantha digitale were dominant species. From the view-point of vertical distribution Aglantha digitale is inhabiting in the depth of 0 300 m and with the maximum in the depth of 50 m to 100 m.

  19. Chapter 50: Geology and tectonic development of the Amerasia and Canada Basins, Arctic Ocean

    Science.gov (United States)

    Grantz, A.; Hart, P.E.; Childers, V.A.

    2011-01-01

    Amerasia Basin is the product of two phases of counterclockwise rotational opening about a pole in the lower Mackenzie Valley of NW Canada. Phase 1 opening brought ocean-continent transition crust (serpentinized peridotite?) to near the seafloor of the proto-Amerasia Basin, created detachment on the Eskimo Lakes Fault Zone of the Canadian Arctic margin and thinned the continental crust between the fault zone and the proto-Amerasia Basin to the west, beginning about 195 Ma and ending prior to perhaps about 160 Ma. The symmetry of the proto-Amerasia Basin was disrupted by clockwise rotation of the Chukchi Microcontinent into the basin from an original position along the Eurasia margin about a pole near 72??N, 165 Wabout 145.5-140 Ma. Phase 2 opening enlarged the proto-Amerasia Basin by intrusion of mid-ocean ridge basalt along its axis between about 131 and 127.5 Ma. Following intrusion of the Phase 2 crust an oceanic volcanic plateau, the Alpha-Mendeleev Ridge LIP (large igneous province), was extruded over the northern Amerasia Basin from about 127 to 89-75 Ma. Emplacement of the LIP halved the area of the Amerasia Basin, and the area lying south of the LIP became the Canada Basin. ?? 2011 The Geological Society of London.

  20. Chapter 49: A first look at the petroleum geology of the Lomonosov Ridge microcontinent, Arctic Ocean

    Science.gov (United States)

    Moore, T.E.; Grantz, A.; Pitman, J.K.; Brown, P.J.

    2011-01-01

    The Lomonosov microcontinent is an elongated continental fragment that transects the Arctic Ocean between North America and Siberia via the North Pole. Although it lies beneath polar pack ice, the geological framework of the microcontinent is inferred from sparse seismic reflection data, a few cores, potential field data and the geology of its conjugate margin in the Barents-Kara Shelf. Petroleum systems inferred to be potentially active are comparable to those sourced by condensed Triassic and Jurassic marine shale of the Barents Platform and by condensed Jurassic and (or) Cretaceous shale probably present in the adjacent Amerasia Basin. Cenozoic deposits are known to contain rich petroleum source rocks but are too thermally immature to have generated petroleum. For the 2008 USGS Circum Arctic Resource Appraisal (CARA), the microcontinent was divided into shelf and slope assessment units (AUs) at the tectonic hinge line along the Amerasia Basin margin. A low to moderate probability of accumulation in the slope AU yielded fully risked mean estimates of 123 MMBO oil and 740 BCF gas. For the shelf AU, no quantitative assessment was made because the probability of petroleum accumulations of the 50 MMBOE minimum size was estimated to be less than 10% owing to rift-related uplift, erosion and faulting. ?? 2011 The Geological Society of London.

  1. Remote Sensing of Ocean Color in the Arctic: Algorithm Development and Comparative Validation. Chapter 9

    Science.gov (United States)

    Cota, Glenn F.

    2001-01-01

    The overall goal of this effort is to acquire a large bio-optical database, encompassing most environmental variability in the Arctic, to develop algorithms for phytoplankton biomass and production and other optically active constituents. A large suite of bio-optical and biogeochemical observations have been collected in a variety of high latitude ecosystems at different seasons. The Ocean Research Consortium of the Arctic (ORCA) is a collaborative effort between G.F. Cota of Old Dominion University (ODU), W.G. Harrison and T. Platt of the Bedford Institute of Oceanography (BIO), S. Sathyendranath of Dalhousie University and S. Saitoh of Hokkaido University. ORCA has now conducted 12 cruises and collected over 500 in-water optical profiles plus a variety of ancillary data. Observational suites typically include apparent optical properties (AOPs), inherent optical property (IOPs), and a variety of ancillary observations including sun photometry, biogeochemical profiles, and productivity measurements. All quality-assured data have been submitted to NASA's SeaWIFS Bio-Optical Archive and Storage System (SeaBASS) data archive. Our algorithm development efforts address most of the potential bio-optical data products for the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS), and GLI, and provides validation for a specific areas of concern, i.e., high latitudes and coastal waters.

  2. A sub-surface eddy at inertial current layer in the Canada Basin, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An Arctic Ocean eddy in sub-surface layer is analyzed in this paper by use of temperature, salinity and current profiles data obtained at an ice camp in the Canada Basin during the second Chinese Arctic Expedition in summer of 2003.In the vertical temperature section, the eddy shows itself as an isolated cold water block at depth of 60 m with a minimum temperature of-1.5℃, about 0.5℃ colder than the ambient water.Isopycnals in the eddy form a pattern of convex, which indicates the eddy is anticyclonic.Although maximum velocity near O.4 m s-1 occurs in the current records observed synchronously, the current pattern is far away from a typical eddy.By further analysis, inertial frequency oscillations with amplitudes comparable with the eddy velocity are found in the sub-surface layer currents.After filter the inertial current and mean current, an axisymmetric current pattern of an eddy with maximum velocity radius of 5 km is obtained.The analysis of the T-S characteristics of the eddy core water and its ambient waters supports the conclusion that the eddy was formed on the Chukchi Shelf and migrated northeastward into the northern Canada Basin.

  3. Picoeukaryote plankton composition off West Spitsbergen at the entrance to the Arctic Ocean.

    Science.gov (United States)

    Kilias, Estelle S; Nöthig, Eva-Maria; Wolf, Christian; Metfies, Katja

    2014-01-01

    Investigation of marine eukaryotic picoplankton composition is limited by missing morphological features for appropriate identification. Consequently, molecular methods are required. In this study, we used 454-pyrosequencing to study picoplankton communities at four stations in the West Spitsbergen Current (WSC; Fram Strait). High abundances of Micromonas pusilla were detected in the station situated closest to Spitsbergen, as seen in surveys of picoplankton assemblages in the Beaufort Sea. At the other three stations, other phylotypes, affiliating with Phaeocystis pouchetii and Syndiniales in the phylogenetic tree, were present in high numbers, dominating most of them. The picoplankton community structures at three of the stations, all with similar salinity and temperature, were alike. At the fourth station, the influence of the East Spitsbergen Current, transporting cold water from the Barents Sea around Spitsbergen, causes different abiotic parameters that result in a significantly different picoeukaryote community composition, which is dominated by M. pusilla. This observation is particularly interesting with regard to ongoing environmental changes in the Arctic. Ongoing warming of the WSC could convey a new picoplankton assemblage into the Arctic Ocean, which may come to affect the dominance of M. pusilla.

  4. Estimation of components of energy balance on drifting ice over Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    卞林根; 陆龙骅; 高志球; 程彦杰; 逯昌贵; 李诗明

    2001-01-01

    Estimation and simulation were carried out for the components of ice-surface energy balance and tur bulent exchange parameters using the flux-profile method and the sinple biosphere model version 2 (SiB2, hereinafter) respectively based on the measured results for the atmosphere in the near-ice-surface layer, which were observed by the First Arctic Scientific Expedition of China in August, 1999 at a joint ice-research station (75°02′N, 160°51′W) on the drifting ice of Arctic Ocean. Evidence suggests that during the melting period of drifting ice the sum of the ice-released sensible heat and effective melting-consumed heat is greater than the net ice-absorbed radiation on the surface, with the excess heat coming via heat conduction from the deep layers of the ice mass. The simulated net radiation is systematical lv 18% greater than the measured results, while the simulated sensible heat flux is systematically 3% lower than the measured ones; and the simulated ice-surface heat flux differs noticeably from its calculation. Hence, we see that al though the measured sequences are short, the simulations of net radiation and sensible heat fluxes by the SiB2 model are comparatively good, the simulation of other forms of fluxes still needs to be improved.

  5. High tolerance of protozooplankton to ocean acidification in an Arctic coastal plankton community

    Directory of Open Access Journals (Sweden)

    N. Aberle

    2012-09-01

    Full Text Available Impacts of ocean acidification (OA on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal protozooplankton (PZP in the following community during the post-bloom period in the Kongsfjorden (Svalbard to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on PZP composition and diversity. Both, the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of protozoans remained unaffected by changes in pCO2/pH. The different pCO2 treatments did not have any effect on food availability and phytoplankton composition and thus no indirect effects e.g. on the total carrying capacity and phenology of PZP could be observed. Our data points at a high tolerance of this Arctic PZP community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include PZP in order to test whether the observed low sensitivity of protozoans to OA is typical for coastal communities where changes in seawater pH occur frequently.

  6. Contrasting activity patterns determined by BrdU incorporation in bacterial ribotypes from the Arctic Ocean in winter

    Directory of Open Access Journals (Sweden)

    Pierre E Galand

    2013-05-01

    Full Text Available The winter Arctic Ocean is one of the most unexplored marine environments from a microbiological perspective. Heterotrophic bacteria maintain their activity at a baseline level during the extremely low energy conditions of the winter, but little is known about the specific phylotypes that have the potential to survive and grow in such harsh environment. In this study, we aimed at identifying actively growing ribotypes in winter Arctic Ocean seawater cultures by experimental incubations with the thymidine analogue bromodeoxyuridine (BrdU, followed by immunocapturing, terminal restriction fragment length polymorphism (TRFLP fingerprinting, cloning and sequencing the 16S rRNA gene. We incubated water collected at different months over the Arctic winter and showed that the actively growing bacterial fraction, taking up BrdU, represented only a subset of the total community. Among the BrdU-labeled bacterial taxa we identified the Flavobacteria Polaribacter, the Alphaproteobacteria SAR11, the Gammaproteobacteria Arctic 96B-16 cluster and, predominately, members of Colwellia spp. Interestingly, Colwellia sequences formed three clusters (93 and 97% pairwise 16S rRNA identity that contributed in contrasting ways to the active communities in the incubations. Polaribacter, Arctic 96B-16 and one cluster of Colwellia were more abundant in the active community represented by the BrdU labelled DNA. In contrast, SAR11 and two other Colwellia clusters were underrepresented in the BrdU labelled community compared to total communities. Despite the limitation of the long incubations needed to label slow growing arctic communities, the BrdU approach revealed the potential for active growth in low-energy conditions in some relevant groups of polar bacteria, including Polaribacter and Arctic 96B-16. Moreover, under similar incubation conditions, the growth of different Colwellia ribotypes varied, suggesting that related clusters of Colwellia may have distinct

  7. Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean.

    Science.gov (United States)

    Roth, Ethan H; Schmidt, Val; Hildebrand, John A; Wiggins, Sean M

    2013-04-01

    U.S. Coast Guard Cutter Healy's underwater radiated noise signature was characterized in the central Arctic Ocean during different types of ice-breaking operations. Propulsion modes included transit in variable ice cover, breaking heavy ice with backing-and-ramming maneuvers, and dynamic positioning with the bow thruster in operation. Compared to open-water transit, Healy's noise signature increased approximately 10 dB between 20 Hz and 2 kHz when breaking ice. The highest noise levels resulted while the ship was engaged in backing-and-ramming maneuvers, owing to cavitation when operating the propellers astern or in opposing directions. In frequency bands centered near 10, 50, and 100 Hz, source levels reached 190-200 dB re: 1 μPa at 1 m (full octave band) during ice-breaking operations.

  8. Evolution of the eddy field in the Arctic Ocean's Canada Basin, 2005-2015

    Science.gov (United States)

    Zhao, Mengnan; Timmermans, Mary-Louise; Cole, Sylvia; Krishfield, Richard; Toole, John

    2016-08-01

    The eddy field across the Arctic Ocean's Canada Basin is analyzed using Ice-Tethered Profiler (ITP) and moored measurements of temperature, salinity, and velocity spanning 2005 to 2015. ITPs encountered 243 eddies, 98% of which were anticyclones, with approximately 70% of these having anomalously cold cores. The spatially and temporally varying eddy field is analyzed accounting for sampling biases in the unevenly distributed ITP data and caveats in detection methods. The highest concentration of eddies was found in the western and southern portions of the basin, close to topographic margins and boundaries of the Beaufort Gyre. The number of lower halocline eddies approximately doubled from 2005-2012 to 2013-2014. The increased eddy density suggests more active baroclinic instability of the Beaufort Gyre that releases available potential energy to balance the wind energy input; this may stabilize the Gyre spin-up and associated freshwater increase.

  9. Insights into the coupling of upper ocean-benthic carbon dynamics in the western Arctic Ocean from an isotopic (13C,234Th) perspective

    Institute of Scientific and Technical Information of China (English)

    ZHANG Run; CHEN Min; MA Qiang; CAO Jianping; QIU Yusheng

    2015-01-01

    The coupling of upper ocean-benthic carbon dynamics in the ice-free western Arctic Ocean (the Chukchi Sea and the Canada Basin) was evaluated during the late July–early September 2003 using natural stable (13C) and radioactive (238U-234Th) isotope tracers. POC export flux estimated from234Th/238U disequilibria and dissolved CO2 concentration ([CO2(aq)]) pointed out that the strengthened biological pump in the Chukchi Shelf have significantly lowered [CO2(aq)] and altered the magnitude of isotopic (12C/13C) fractionation during carbon fixation in the surface ocean. Further,d13C signatures of surface sediments (d13Csed) are positively correlated to those of weightedd13CPOC in upper ocean (d13Csed =13.64+1.56×d13CPOC,r2=0.73,p<0.01), suggesting that the POC isotopic signals from upper ocean have been recorded in the sediments, partly due to the rapid export of particles as evidenced by low residence times of the highly particle-reactive234Th from the upper water column. It is suggested that there probably exists an upper ocean-benthic coupling of carbon dynamics, which likely assures the sedimentaryd13C record an indicator of paleo-CO2 in the western Arctic Ocean.

  10. Source and formation of the upper halocline of the Arctic Ocean

    Science.gov (United States)

    Anderson, Leif G.; Andersson, Per S.; BjöRk, GöRan; Peter Jones, E.; JutterströM, Sara; WâHlströM, IréNe

    2013-01-01

    AbstractThe upper halocline of the Arctic Ocean has a distinct chemical signature with high nutrient concentrations as well as low oxygen and pH values. This signature is formed in the Chukchi and East Siberian seas, by a combination of mineralization of organic matter and release of decay products to the sea ice brine enriched bottom water. Salinity and total alkalinity data show that the fraction of sea ice brine in the nutrient-enriched upper halocline water in the central Arctic Ocean is up to 4%. In the East Siberian Sea the bottom waters with exceptional high nutrient concentration and low pH have typically between 5 and 10% of sea ice brine as computed from salinity and oxygen-18 values. On the continental slope, over bottom depths of 150-200 m, the brine contribution was 6% at the nutrient maximum depth (50-100 m). At the same location as well as over the deeper basin the silicate maximum was found over a wider salinity range than traditionally found in the Canada Basin, in agreement with earlier observations east of the Chukchi Plateau. A detailed evaluation of the chemical and the temperature-salinity properties suggests at least two different areas for the formation of the nutrient-rich halocline within the East Siberian Sea. This has not been observed before 2004 and it could be a sign of a changing marine climate in the East Siberian Sea, caused by more open water in the summer season followed by more sea ice formation and brine production in the fall/winter.

  11. Wintertime Arctic Ocean sea water properties and primary marine aerosol concentrations

    Directory of Open Access Journals (Sweden)

    J. Zábori

    2012-06-01

    Full Text Available Sea spray aerosols are an important part of the climate system through their direct and indirect effects. Due to the diminishing sea ice, the Arctic Ocean is one of the most rapidly changing sea spray aerosol source areas. However, the influence of these changes on primary particle production is not known.

    In laboratory experiments we examined the influence of Arctic Ocean water temperature, salinity and oxygen saturation on primary particle concentration characteristics. Sea water temperature was identified as the most important of these parameters. A strong decrease in sea spray aerosol production with increasing water temperature was observed for water temperatures between −1 °C and 9 °C. Aerosol number concentrations decreased from at least 1400 cm−3 to 350 cm−3. In general, the aerosol number size distribution exhibited a robust shape with one mode close to Dp 0.2 μm with approximately 45% of particles at smaller sizes. Changes in sea water temperature did not result in pronounced change of the shape of the aerosol size distribution, only in the magnitude of the concentrations. Our experiments indicate that changes in aerosol emissions are most likely linked to changes of the physical properties of sea water at low temperatures. The observed strong dependence of sea spray aerosol concentrations on sea water temperature, with a large fraction of the emitted particles in the typical cloud condensation nuclei size range, provide strong arguments for a more careful consideration of this effect in climate models.

  12. Wintertime Arctic Ocean sea water properties and primary marine aerosol concentrations

    Directory of Open Access Journals (Sweden)

    J. Zábori

    2012-11-01

    Full Text Available Sea spray aerosols are an important part of the climate system through their direct and indirect effects. Due to the diminishing sea ice, the Arctic Ocean is one of the most rapidly changing sea spray aerosol source areas. However, the influence of these changes on primary particle production is not known.

    In laboratory experiments we examined the influence of Arctic Ocean water temperature, salinity, and oxygen saturation on primary particle concentration characteristics. Sea water temperature was identified as the most important of these parameters. A strong decrease in sea spray aerosol production with increasing water temperature was observed for water temperatures between −1°C and 9°C. Aerosol number concentrations decreased from at least 1400 cm−3 to 350 cm−3. In general, the aerosol number size distribution exhibited a robust shape with one mode close to dry diameter Dp 0.2 μm with approximately 45% of particles at smaller sizes. Changes in sea water temperature did not result in pronounced change of the shape of the aerosol size distribution, only in the magnitude of the concentrations. Our experiments indicate that changes in aerosol emissions are most likely linked to changes of the physical properties of sea water at low temperatures. The observed strong dependence of sea spray aerosol concentrations on sea water temperature, with a large fraction of the emitted particles in the typical cloud condensation nuclei size range, provide strong arguments for a more careful consideration of this effect in climate models.

  13. Morphological variability of the planktonic foraminifer Neogloboquadrina pachyderma from ACEX cores: Implications for late pleistocene circulation in the Arctic Ocean

    Science.gov (United States)

    Eynaud, F.; Cronin, T. M.; Smith, S.A.; Zaragosi, S.; Mavel, J.; Mary, Y.; Mas, V.; Pujol, C.

    2009-01-01

    Planktonic foraminifera populations were studied throughout the top 25 meters of the IODP ACEX 302 Hole 4C from the central Arctic Ocean at a resolution varying from 5cm (at the top of the record) to 10cm. Planktonic foraminifera occur in high absolute abundances only in the uppermost fifty centimetres and are dominated by the taxa Neogloboquadrina pachyderma. Except for a few intermittent layers below this level, most samples are barren of calcareous microfossils. Within the topmost sediments, Neogloboquadrina pachyderma specimens present large morphological variability in the shape and number of chambers in the final whorl, chamber sphericity, size, and coiling direction. Five morphotypes were identified among the sinistral (sin.) population (Nps-1 to Nps-5), including a small form (Nps-5) that is similar to a non-encrusted normal form also previously identified in the modern Arctic Ocean water masses. Twenty five percent of the sinistral population is made up by large specimens (Nps-2, 3,4), with a maximal mean diameter larger than 250??m. Following observations made in peri-Arctic seas (Hillaire-Marcel et al. 2004), we propose that occurrence of these large-sized specimens of N. pachyderma (sin.) in the central Arctic Ocean sediments could sign North Atlantic water sub-surface penetration.

  14. Iodine speciation in aerosol particle samples collected over the sea between offshore China and the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    KANG Hui; XU Siqi; YU Xiawei; LI Bing; LIU Wei; YANG Hongxia; XIE Zhouqing

    2015-01-01

    Iodine species collected by an onboard PM10 particle sampling system during the Second Chinese National Arctic Research Expedition (July–September 2003) were measured using inductively coupled plasma mass spectrometry and ion chromatography-inductively coupled plasma mass spectrometry. Iodine (I−) was detected in all samples over the Arctic Ocean, whereas additional iodine species including insoluble iodine, soluble organic iodine plus I− were detected over the northwestern Paciifc Ocean. The results suggest that the main form of iodine is different within the Arctic Ocean than it is outside. Enrichment factor values showed moderate enrichment of iodine in the northwestern Paciifc, whereas a high enrichment factor was found in polar regions, implying sources other than sea salt. A potential explanation was ascribed to the role of sea ice melt in the Arctic and rapid growth of algae in seawater, which enhances the production of iodocarbon and air-sea exchange. This was conifrmed by the larger values of total iodine in 2008 than in 2003, with greater sea ice melt in the former year. In comparison with earlier reports, ratios of iodate to iodide (IO3−/I−) were much smaller than 1.0. These ratios were also different from modeling results, implying more complicated cycles of atmospheric iodine than are presently understood.

  15. Diversity of cultured photosynthetic flagellates in the North East Pacific and Arctic Oceans in summer

    Science.gov (United States)

    Balzano, S.; Gourvil, P.; Siano, R.; Chanoine, M.; Marie, D.; Lessard, S.; Sarno, D.; Vaulot, D.

    2012-06-01

    During the MALINA cruise (summer 2009) an extensive effort was undertaken to isolate phytoplankton strains from the North East (NE) Pacific Ocean, the Bering Strait, and the Beaufort Sea. Strains were isolated by flow cytometry sorting (FCS) and pipetting before or after phytoplankton enrichment of seawater samples. Strains were isolated both onboard and back in the laboratory and cultured at 4 °C under light/dark conditions. Overall, we isolated and characterised by light microscopy and 18S rRNA gene sequencing 104 strains of photosynthetic flagellates which grouped into 21 genotypes (defined by 99.5% 18S rRNA gene sequence similarity) mainly affiliated to Chlorophyta and Heterokontophyta. The taxon most frequently isolated was an Arctic ecotype of the green algal genus Micromonas (Arctic Micromonas) which was almost the only phytoplankter recovered within picoplankton (≤ 2 μm) size range. Strains of Arctic Micromonas as well as three unidentified strains related to the same genus were identified in further details by sequencing the Internal Transcribed Spacer (ITS) region of the rRNA operon. The MALINA Micromonas strains share identical 18S rRNA and ITS sequences suggesting high genetic homogeneity within Arctic Micromonas. The unidentified strains form a genotype likely belonging to a new genus within the family Mamiellaceae to which Micromonas belongs. Other green algae genotypes from the genera Nephroselmis, Chlamydomonas, Pyramimonas were also isolated whereas Heterokontophyta included Pelagophyceae, Dictyochophyceae and Chrysophyceae. Dictyochophyceae included Pedinellales which could not be identified to the genus level whereas Chrysophyceae comprised Dinobryon faculiferum. Moreover, we isolated Rhodomonas sp. as well as a few Haptophyta and dinoflagellates. We identified the dinoflagellate Woloszynskia cincta by Scanning Electron Microscopy (SEM) and 28S rRNA gene sequencing. Our morphological analyses show that this species possess the diagnostic

  16. U-Pb zircon geochronology of Caledonian age orthogneisses dredged from the Chukchi Borderland, Arctic Ocean.

    Science.gov (United States)

    Brumley, K.; Miller, E. L.; Mayer, L. A.; Wooden, J.; Grove, M.

    2012-04-01

    Over 500 kilos of metamorphic rock was dredged from outcrops along a steep normal fault scarp in the central Chukchi Borderland in 2009 (HLY0905) from water depths of between about 2500-1400m. The rocks in the dredge included broken angular cobbles and boulder-sized samples of amphibolites, orthogneisses, and granitoids of the same amphibolite facies metamorphic grade, as well as gravel to small cobble-sized ice rafted debris of various rock types. Zircons were separated from two of the orthogneiss samples, and single grain zircon U-Pb ages were determined by SHRIMP analysis to be 428 Ma ± 3.4 for both samples (N=60). Several zircon grains had distinct igneous cores that ranged in age from about 928-1200 Ma (n=7) with two older grains (1700, 1760 Ma). The Caledonian orogenic belt developed in the Ordovician to Devonian affecting northern Europe, Greenland and Arctic Canada. Caledonian deformational trends continue into the Arctic and disappear at the rifted margin of the Arctic Ocean. Syn-orogenic magmatism in the Barents region date deformation in this region during the Caledonian event to have occurred between about 450-410 Ma (Johansson et al., 2005; Gee et al., 2006; Gee and Tebenkov, 2004). Grenville age plutons (900-1250Ma) that were later involved in Caledonian deformation and intruded by 410-450 Ma aged plutons are found on western and eastern Svalbard (Johansson et al., 2005), eastern Greenland, and the Pearya Terrane of northern Ellesmere Island (Trettin,1986, 1992). The Franklinian basement of Arctic Alaska and Canada do not share these Grenvillian ages (Trentin et al, 1987). This suggests that the inherited zircon cores in the Chukchi Borderland orthogneisses were derived, at least in part, from an older Grenvillian basement like that of Pearya, Svalbard and parts of Greenland, or through sediments eroded from these sources, and later intruded by Caledonian aged granites. This constrains the pre-rift location of the Chukchi Borderland to be within the

  17. An Arctic source for the Great Salinity Anomaly - A simulation of the Arctic ice-ocean system for 1955-1975

    Science.gov (United States)

    Hakkinen, Sirpa

    1993-01-01

    The paper employs a fully prognostic Arctic ice-ocean model to study the interannual variability of sea ice during the period 1955-1975 and to explain the large variability of the ice extent in the Greenland and Iceland seas during the late 1960s. The model is used to test the contention of Aagaard and Carmack (1989) that the Great Salinity Anomaly (GSA) was a consequence of the anomalously large ice export in 1968. The high-latitude ice-ocean circulation changes due to wind field changes are explored. The ice export event of 1968 was the largest in the simulation, being about twice as large as the average and corresponding to 1600 cu km of excess fresh water. The simulations suggest that, besides the above average ice export to the Greenland Sea, there was also fresh water export to support the larger than average ice cover. The model results show the origin of the GSA to be in the Arctic, and support the view that the Arctic may play an active role in climate change.

  18. Reflection and transmission of irradiance by snow and sea ice in the central Arctic Ocean in summer 2010

    OpenAIRE

    Lei, Ruibo; Zhang, Zhanhai; Matero, Ilkka; Cheng, Bin; Li, Qun; Huang, Wenfeng

    2012-01-01

    Reflection and transmission of irradiance by the combined snow and sea ice layer were measured at an ice camp (ca. 10 days) and several short-term stations (ca. 2 h) established in the western sector of the Arctic Ocean above 80°N during the 2010 summer. These measurements were made with an intention to quantify the apparent optical properties of snow and sea ice, and to evaluate their roles in the mass balance of snow-covered sea ice in the High Arctic. The integrated 350–920 nm albedo range...

  19. Sea surface height determination in the arctic ocean from Cryosat2 SAR data, the impact of using different empirical retrackers

    DEFF Research Database (Denmark)

    Jain, Maulik; Andersen, Ole Baltazar; Stenseng, Lars

    2012-01-01

    Cryosat2 Level 1B SAR data can be processed using different empirical retrackers to determine the sea surface height and its variations in the Arctic Ocean. Two improved retrackers based on the combination of OCOG (Offset Centre of Gravity), Threshold methods and Leading Edge Retrieval is used...... to estimate the sea surface height in the Arctic Region. This sea surface height determination is to be compared with the Level2 sea surface height components available in the Cryosat2 data. Further a comparison is done with the marine gravity field for retracker performance evaluation....

  20. Ice–ocean coupled computations for sea-ice prediction to support ice navigation in Arctic sea routes

    Directory of Open Access Journals (Sweden)

    Liyanarachchi Waruna Arampath De Silva

    2015-11-01

    Full Text Available With the recent rapid decrease in summer sea ice in the Arctic Ocean extending the navigation period in the Arctic sea routes (ASR, the precise prediction of ice distribution is crucial for safe and efficient navigation in the Arctic Ocean. In general, however, most of the available numerical models have exhibited significant uncertainties in short-term and narrow-area predictions, especially in marginal ice zones such as the ASR. In this study, we predict short-term sea-ice conditions in the ASR by using a mesoscale eddy-resolving ice–ocean coupled model that explicitly treats ice floe collisions in marginal ice zones. First, numerical issues associated with collision rheology in the ice–ocean coupled model (ice–Princeton Ocean Model [POM] are discussed and resolved. A model for the whole of the Arctic Ocean with a coarser resolution (about 25 km was developed to investigate the performance of the ice–POM model by examining the reproducibility of seasonal and interannual sea-ice variability. It was found that this coarser resolution model can reproduce seasonal and interannual sea-ice variations compared to observations, but it cannot be used to predict variations over the short-term, such as one to two weeks. Therefore, second, high-resolution (about 2.5 km regional models were set up along the ASR to investigate the accuracy of short-term sea-ice predictions. High-resolution computations were able to reasonably reproduce the sea-ice extent compared to Advanced Microwave Scanning Radiometer–Earth Observing System satellite observations because of the improved expression of the ice–albedo feedback process and the ice–eddy interaction process.

  1. Large-scale temperature and salinity changes in the upper Canadian Basin of the Arctic Ocean at a time of a drastic Arctic Oscillation inversion

    Directory of Open Access Journals (Sweden)

    P. Bourgain

    2013-04-01

    Full Text Available Between 2008 and 2010, the Arctic Oscillation index over Arctic regions shifted from positive values corresponding to more cyclonic conditions prevailing during the 4th International Polar Year (IPY period (2007–2008 to extremely negative values corresponding to strong anticyclonic conditions in 2010. In this context, we investigated the recent large-scale evolution of the upper western Arctic Ocean, based on temperature and salinity summertime observations collected during icebreaker campaigns and from ice-tethered profilers (ITPs drifting across the region in 2008 and 2010. Particularly, we focused on (1 the freshwater content which was extensively studied during previous years, (2 the near-surface temperature maximum due to incoming solar radiation, and (3 the water masses advected from the Pacific Ocean into the Arctic Ocean. The observations revealed a freshwater content change in the Canadian Basin during this time period. South of 80° N, the freshwater content increased, while north of 80° N, less freshening occurred in 2010 compared to 2008. This was more likely due to the strong anticyclonicity characteristic of a low AO index mode that enhanced both a wind-generated Ekman pumping in the Beaufort Gyre and a possible diversion of the Siberian River runoff toward the Eurasian Basin at the same time. The near-surface temperature maximum due to incoming solar radiation was almost 1 °C colder in the southern Canada Basin (south of 75° N in 2010 compared to 2008, which contrasted with the positive trend observed during previous years. This was more likely due to higher summer sea ice concentration in 2010 compared to 2008 in that region, and surface albedo feedback reflecting more sun radiation back in space. The Pacific water (PaW was also subjected to strong spatial and temporal variability between 2008 and 2010. In the Canada Basin, both summer and winter PaW signatures were stronger between 75° N and 80° N. This was more likely

  2. Structure and variability of the boundary current in the Eurasian Basin of the Arctic Ocean

    Science.gov (United States)

    Pnyushkov, Andrey V.; Polyakov, Igor V.; Ivanov, Vladimir V.; Aksenov, Yevgeny; Coward, Andrew C.; Janout, Markus; Rabe, Benjamin

    2015-07-01

    temperature structure that emerged in this region of the Arctic Ocean in the most recent decade, suggest a shift of the EB toward a new, more dynamic state. This also likely suggests that the EB interior will become more susceptible to future climate change. Evaluating properties of the ACBC, its temporal variability at time scales from a season to several years, and possible governing mechanisms, this study contributes to a better understanding of Arctic Ocean circulation.

  3. Sensitivity of the Arctic Climate to Leads in a Coupled Atmosphere-Mixed Layer Ocean Model.

    Science.gov (United States)

    Vavrus, Stephen J.

    1995-02-01

    The thermodynamic sea ice code in a coupled atmosphere-mixed layer ocean GCM has been altered to allow the presence of open water within an ice pack (leads) and a prescribed turbulent oceanic heat flux at the ice bottom. Two experiments with the GCM are then performed: one with leads included and one without. A comparison between the two model runs is presented, in addition to a comparison between observations and the simulation with leads. Selected sea ice and atmospheric variables in the high-latitude Northern Hemisphere are analyzed to assess the sensitivity of these climatic components to the presence of leads and to identify feedback mechanisms that are introduced by leads.The inclusion of leads causes Northern Hemispheric sea ice concentration to decrease in every season, with year-round statistically significant reductions at the highest latitude band (81°N). Using the improved sea ice code, the model's simulation of sea ice concentration in the central Arctic is consistent with observations in every season. Simulated summertime sea ice concentration at 81°N averages 93.8%, which agrees well with observations. There is a pronounced longitudinal variation to the lead fraction in summer, with the smallest values (0.01) neat the Canadian Archipelago and the largest (0.25) north of the East Siberian Sea. Consistent with observations, the model produces wintertime turbulent sensible heat fluxes over leads that are one to two orders of magnitude larger than over adjacent sea ice and of the opposite sign. Annual solar radiation absorption by leads in the central Arctic is 1.8 times as large as over adjacent sea ice, resulting in a summertime shortwave energy gain of over 2.5 W m2 at 8 1°N compared to the model run without leads.The inclusion of leads causes thicker sea ice in every season, because the very rapid ice growth rate in the leads is translated into enhanced accretion at the bottom of adjacent sea ice once a prescribed minimum lead fraction is reached

  4. Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water

    Institute of Scientific and Technical Information of China (English)

    WANG Jia; JIN Mei-bing; Jun Takahashi; Tatsuo Suzuki; Igor V Polyakov; Kohei Mizobata; Moto Ikeda; Fancois J.Saucier; Markus Meier

    2008-01-01

    This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations. The model, with no flux adjustment, reproduces well the Atlantic Water core temperature (AWCT) in the Arctic Ocean and shows that four largest decadalscale warming episodes occurred in the 1930's, 70s, 80s, and 90s, in agreement with the hydrographic observational data. The difference is that there was no pre-warming prior to the 1930s episode, while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s, leading the 1990s into the largest and prolonged warming in the 20th century. Over the last century, the simulated heat transport via Fram Strait and the Barents Sea was estimated to be, on average, 31.32 TW and 14.82TW, respectively, while the Bering Strait also provides 15.94 TW heat into the western Arctic Ocean. Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT ( C =0.75 ) at Olag. The modeled North Atlantic Oscillation ( NAO ) index has a significant correlation with the heat transport ( C = 0.37 ). The observed AWCT has a significant correlation with both the modeled AWCT (C =0.49) and the heat transport (C =0.41 ).However, the modeled NAO index does not significantly correlate with either the observed AWCT (C =0.03 ) or modeled AWCT (C = 0. 16) at a zero-lag, indicating that the Arctic climate system is far more complex than expected.

  5. Splitting of Atlantic water transport towards the Arctic Ocean into the Fram Strait and Barents Sea Branches - mechanisms and consequences

    Science.gov (United States)

    Beszczynska-Möller, Agnieszka; Skagseth, Øystein; von Appen, Wilken-Jon; Walczowski, Waldemar; Lien, Vidar

    2016-04-01

    The heat content in the Arctic Ocean is to a large extent determined by oceanic advection from the south. During the last two decades the extraordinary warm Atlantic water (AW) inflow has been reported to progress through the Nordic Seas into the Arctic Ocean. Warm anomalies can result from higher air temperatures (smaller heat loss) in the Nordic Seas, and/or from an increased oceanic advection. But the ultimate fate of warm anomalies of Atlantic origin depends strongly on their two possible pathways towards the Arctic Ocean. The AW temperature changes from 7-10°C at the entrance to the Nordic Seas, to 6-6.5°C in the Barents Sea opening and 3-3.5°C as the AW leaving Fram Strait enters the Arctic Ocean. When AW passes through the shallow Barents Sea, nearly all its heat is lost due to atmospheric cooling and AW looses its signature. In the deep Fram Strait the upper part of Atlantic water becomes transformed into a less saline and colder surface layer and thus AW preserves its warm core. A significant warming and high variability of AW volume transport was observed in two recent decades in the West Spitsbergen Current, representing the Fram Strait Branch of Atlantic inflow. The AW inflow through Fram Strait carries between 26 and 50 TW of heat into the Arctic Ocean. While the oceanic heat influx to the Barents Sea is of a similar order, the heat leaving it through the northern exit into the Arctic Ocean is negligible. The relative strength of two Atlantic water branches through Fram Strait and the Barents Sea governs the oceanic heat transport into the Arctic Ocean. According to recently proposed mechanism, the Atlantic water flow in the Barents Sea Branch is controlled by the strength of atmospheric low over the northern Barents Sea, acting through a wind-induced Ekman divergence, which intensifies eastward AW flow. The Atlantic water transport in the Fram Strait Branch is mainly forced by the large-scale low-pressure system over the eastern Norwegian and

  6. Philinidae, Laonidae and Philinorbidae (Gastropoda: Cephalaspidea: Philinoidea) from the northeastern Pacific Ocean and the Beaufort Sea (Arctic Ocean).

    Science.gov (United States)

    Valdés, Ángel; Cadien, Donald B; Gosliner, Terrence M

    2016-08-08

    Based on morphological data a total of nine native species of Philinidae are recognized from the northeastern Pacific including the Bering Sea and the adjacent Arctic Ocean (Beaufort Sea). Four of them have been previously described: Philine ornatissima Yokoyama, 1927, Philine bakeri Dall, 1919, Philine polystrigma (Dall, 1908), and Philine hemphilli Dall, 1919. Five of them are new and described herein: Philine mcleani sp. nov., Philine baxteri sp. nov., Philine malaquiasi sp. nov., Philine wareni sp. nov., and Philine harrisae sp. nov. These species display a substantial degree of variation in internal and external morphological traits (i.e., presence/absence of gizzard plates, different radular structure and tooth morphology, various reproductive anatomical features) and it is likely that they belong to different clades (genera). However, in the absence of a comprehensive phylogeny for Philine, they are here provisionally regarded as Philine sensu lato. In addition to the nine native species, two introduced species: Philine orientalis A. Adams, 1854 and Philine auriformis Suter, 1909 are here illustrated and compared to the native species to facilitate identification. Finally, two species previously considered members of Philinidae are examined anatomically and confirmed as members of Laonidae, Laona californica (Willett, 1944) and Philinorbidae, Philinorbis albus (Mattox, 1958), based on morphological data.

  7. Contribution of a pathway through the Arctic Ocean to the re cent reduction in the ice cover

    Institute of Scientific and Technical Information of China (English)

    Motoyoshi Ikeda

    2008-01-01

    The sea ice cover in the Arctic Ocean has been reducing and hit the low record in the summer of 2007. The anomaly was extremely large in the Pacific sector.The sea level height in the Bering Sea vs. the Greenland Sea has been analyzed and compared with the current meter data through the Bering Strait. A recent peak existed as a consequence of atmospheric circulation and is considered to contribute to inflow of the Pacific Water into the Arctic Basin. The timing of the Pacific Water inflow matched with the sea ice reduction in the Pacific sector and suggests a significant increase in heat flux. This component should be included in the model prediction for answering the question when the Arctic sea ice becomes a seasonal ice cover.

  8. The instability of diffusive convection and its implication for the thermohaline staircases in the deep Arctic Ocean

    Science.gov (United States)

    Zhou, S.-Q.; Qu, L.; Lu, Y.-Z.; Song, X.-L.

    2014-02-01

    In the present study, the classical description of diffusive convection is updated to interpret the instability of diffusive interfaces and the dynamical evolution of the bottom layer in the deep Arctic Ocean. In the new consideration of convective instability, both the background salinity stratification and rotation are involved. The critical Rayleigh number of diffusive convection is found to vary from 103 to 1011 in the deep Arctic Ocean as well as in other oceans and lakes. In such a wide range of conditions, the interface-induced thermal Rayleigh number is shown to be consistent with the critical Rayleigh number of diffusive convection. In most regions, background salinity stratification is found to be the main hindrance to the occurrence of convecting layers. With the new parameterization, it is predicted that the maximum thickness of the bottom layer is 1051 m in the deep Arctic Ocean, which is close to the observed value of 929 m. The evolution time of the bottom layer is predicted to be ~ 100 yr, which is on the same order as that based on 14C isolation age estimation.

  9. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part II: Liquid freshwater

    Science.gov (United States)

    Wang, Qiang; Ilicak, Mehmet; Gerdes, Rüdiger; Drange, Helge; Aksenov, Yevgeny; Bailey, David A.; Bentsen, Mats; Biastoch, Arne; Bozec, Alexandra; Böning, Claus; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Curry, Beth; Danabasoglu, Gokhan; Danilov, Sergey; Fernandez, Elodie; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Iovino, Doroteaciro; Jahn, Alexandra; Jung, Thomas; Large, William G.; Lee, Craig; Lique, Camille; Lu, Jianhua; Masina, Simona; Nurser, A. J. George; Rabe, Benjamin; Roth, Christina; Salas y Mélia, David; Samuels, Bonita L.; Spence, Paul; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Xuezhu; Yeager, Steve G.

    2016-03-01

    The Arctic Ocean simulated in 14 global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the gateways where the ocean volume transport determines the FW transport variability. The variation of liquid FWC is induced by both the surface FW flux (associated with sea ice production) and lateral liquid FW transport, which are in phase when averaged on decadal time scales. The liquid FWC shows an increase starting from the mid-1990s, caused by the reduction of both sea ice formation and liquid FW export, with the former being more significant in most of the models. The mean state of the FW budget is less consistently simulated than the temporal variability. The model ensemble means of liquid FW transport through the Arctic gateways compare well with observations. On average, the models have too high mean FWC, weaker upward trends of FWC in the recent decade than the observation, and low consistency in the temporal variation of FWC spatial distribution, which needs to be further explored for the purpose of model development.

  10. Quantifying the Bering Strait Oceanic Fluxes and their Impacts on Sea-Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014

    Science.gov (United States)

    2014-09-30

    Impacts on Sea- Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014 Rebecca Woodgate Polar Science...from the Pacific, are critical to the water properties of the Chukchi Sea, act as a trigger of sea- ice melt in the Chukchi, provide a subsurface...source of heat to the Arctic in winter (with possible impacts on sea- ice ), and are a major component of freshwater input to the Arctic (Figures 1 and 2

  11. Chapter 50 Geology and tectonic development of the Amerasia and Canada Basins, Arctic Ocean

    Science.gov (United States)

    Grantz, Arthur; Hart, Patrick E.; Childers, Vicki A

    2011-01-01

    Amerasia Basin is the product of two phases of counterclockwise rotational opening about a pole in the lower Mackenzie Valley of NW Canada. Phase 1 opening brought ocean–continent transition crust (serpentinized peridotite?) to near the seafloor of the proto-Amerasia Basin, created detachment on the Eskimo Lakes Fault Zone of the Canadian Arctic margin and thinned the continental crust between the fault zone and the proto-Amerasia Basin to the west, beginning about 195 Ma and ending prior to perhaps about 160 Ma. The symmetry of the proto-Amerasia Basin was disrupted by clockwise rotation of the Chukchi Microcontinent into the basin from an original position along the Eurasia margin about a pole near 72°N, 165 W about 145.5–140 Ma. Phase 2 opening enlarged the proto-Amerasia Basin by intrusion of mid-ocean ridge basalt along its axis between about 131 and 127.5 Ma. Following intrusion of the Phase 2 crust an oceanic volcanic plateau, the Alpha–Mendeleev Ridge LIP (large igneous province), was extruded over the northern Amerasia Basin from about 127 to 89–75 Ma. Emplacement of the LIP halved the area of the Amerasia Basin, and the area lying south of the LIP became the Canada Basin.

  12. Vertical fluxes of nitrate in the seasonal nitracline of the Atlantic sector of the Arctic Ocean

    Science.gov (United States)

    Randelhoff, Achim; Fer, Ilker; Sundfjord, Arild; Tremblay, Jean-Éric; Reigstad, Marit

    2016-07-01

    This study compiles colocated oceanic observations of high-resolution vertical profiles of nitrate concentration and turbulent microstructure around the Svalbard shelf slope, covering both the permanently ice-free Fram Strait and the pack ice north of Svalbard. The authors present an overview over the seasonal evolution of the distribution of nitrate and its relation to upper ocean stratification. The average upward turbulent diffusive nitrate flux across the seasonal nitracline during the Arctic summer season is derived, with average values of 0.3 and 0.7 mmol m-2 d-1 for stations with and without ice cover, respectively. The increase under ice-free conditions is attributed to different patterns of stratification under sea ice versus open water. The nitrate flux obtained from microstructure measurements lacked a seasonal signal. However, bottle incubations indicate that August nitrate uptake was reduced by more than an order of magnitude relative to the May values. It remains inconclusive whether the new production was limited by an unidentified factor other than NO3- supply in late summer, or the uptake was underestimated by the incubation method.

  13. Multiyear Survey of the Distribution and Fate of Biomarkers in the Atlantic Arctic Ocean

    Science.gov (United States)

    Fietz, S.; Rosell Mele, A.; Rueda, G.; Martinez Garcia, A.; Hambach, B.; Viladrich, N.; Barrera Sansón, A.; Rossi, S.; Ziveri, P.

    2010-12-01

    Biogeochemical signatures derived from organisms thriving in the ocean water column are driven by environmental conditions, with highly complex processes linking primary and export productivity. Organic matter input, in-situ production and fate depend on conditions such as sea surface temperature, ice-cover and freshwater input, mixing/stratification regime, fertilization and acidification etc. for which important changes are predicted in subpolar and polar environments. However, the spatial and interannual variability of organic matter distribution and their driving environmental factors in these vast oceanic regions are not fully determined or understood. To gain some new insights into these issues in the Arctic region we have participated in a multiyear survey, based on four summer cruises from 2005 to 2009 following latitudinal transects from the North Atlantic to the Fram Strait, and longitudinal transects from Greenland to Svalbard and collected particulate matter in the water column as well as twenty surface sediments. We focus on biogeochemical markers for terrestrial matter input (e.g., n-alkanes, branched GDGTs), for in-situ productivity and pelagic community composition (e.g., photosynthetic pigments, alkenones, isoprenoid GDGTs) and food-web structure (e.g., fatty acids, sterols). We also collected samples to determine the distribution of specific algal groups (coccolithophores) in this region. Results from the 2008 and 2009 surveys will be presented. Our aim is to compare the organic matter signatures in the upper water column to those in the exported matter that reaches deep water masses and surface sediments.

  14. Freshwater budget of the Canada Basin, Arctic Ocean, from salinity, δ18O, and nutrients

    Science.gov (United States)

    Yamamoto-Kawai, M.; McLaughlin, F. A.; Carmack, E. C.; Nishino, S.; Shimada, K.

    2008-01-01

    The contribution of freshwater components (e.g., meteoric, sea ice, and Pacific water) in the Canada Basin is quantified using salinity, δ18O, and nutrient data collected in 2003 and 2004. The penetration depth of sea ice meltwater is limited to the upper 30 m, and brine, rejected during sea ice formation, is observed from 30 to 250 m depth. The fraction of meteoric water is high in the upper 50 m and decreases with depth. Pacific water entering via Bering Strait is the main source of freshwater below 50 m depth. Bering Strait throughflow, which transports Pacific water with salinity 32.5 together with meteoric water supplied upstream of the Bering Strait, contributes up to 75% of freshwater input (>3200 km3 a-1) to the Canada Basin. The mean residence time of Pacific water in the Canada Basin is estimated to be 11 years. Precipitation and river runoff from both North American and Eurasian continents add >800 km3 a-1 and sea ice formation removes export of ice and liquid fresh water from the Canada Basin contributes ˜40% of the freshwater flux from the Arctic Ocean to the North Atlantic Ocean.

  15. Ocean-ice interactions with possible implications for Arctic ice shelves

    Science.gov (United States)

    Alley, R. B.

    2015-12-01

    Confined ice shelves restrain flow of non-floating ice, allowing ice sheets to grow larger than they otherwise would. Ice shelves lead a precarious existence, subject to fragmentation if sufficient meltwater fills crevasses, and very sensitive to even slight warming of water beneath. Ice shelves tend to exist in the coldest waters in the world ocean, often overlying warmer, more-saline waters. Changes in water temperature or circulation generally shrink existing ice shelves and raise sea level by unbuttressing the non-floating ice, and this is likely the most important control on marine-ending parts of land ice, exceeding the influence of sea-level or accumulation-rate changes. Advance of an ice-shelf grounding line into warmer, deeper water will increase melting rates, reduce buttressing, and tend to stabilize the grounding line near or above the upper limit of that warmer water. This physical understanding indicates that the oceanographic state, and its interaction with tributary ice streams, must have been central in the extent of Arctic ice shelves once sufficient cooling occurred to allow extensive advance of land ice into the ocean.

  16. Solar heating of the Arctic Ocean in the context of ice-albedo feedback

    Science.gov (United States)

    Pinker, Rachel T.; Niu, Xiaolei; Ma, Yingtao

    2014-12-01

    To study the relationship of solar heat input into the Arctic open water and the variations of sea ice extent, improved satellite-based estimates of shortwave radiative (SWR) fluxes and most recent observations of ice extent are used. The SWR flux estimates are based on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and from the Advanced Very High Resolution Radiometer (AVHRR) for the period of 1984-2009. Ice extent information at 25 km resolution comes from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data as generated with the NASA Team algorithm developed by the Oceans and Ice Branch, Laboratory for Hydrospheric Processes, NASA Goddard Space Flight Center. The trends of the solar heat input into the ocean and the open water fraction for 1984-2009 are found to be positive: 0.3%/yr and 0.8%/yr, respectively, at a 99% confidence level. There is an obvious transition region separating the 26 years into two periods: one with moderate change: 1984-2002, and the other with an abrupt growth in both solar heat input and open water fraction: 2003-2009. The impact of the observed changes on the reduction of winter ice growth in 2007 is estimated to be about 44 cm, and a delay in fall freezeup as about 10-36 days.

  17. First scientific dives of the Nereid Under Ice hybrid ROV in the Arctic Ocean.

    Science.gov (United States)

    German, C. R.; Boetius, A.; Whitcomb, L. L.; Jakuba, M.; Bailey, J.; Judge, C.; McFarland, C.; Suman, S.; Elliott, S.; Katlein, C.; Arndt, S.; Bowen, A.; Yoerger, D.; Kinsey, J. C.; Mayer, L.; Nicolaus, M.; Laney, S.; Singh, H.; Maksym, T. L.

    2014-12-01

    The first scientific dives of the new Nereid Under Ice (NUI) hybrid ROV were conducted in the Arctic Ocean in July 2014 on RV Polarstern cruise PS86, a German-US collaboration. NUI is the latest in a family of vehicles derived from the Nereus prototype, using a single optical fiber to provide real-time telemetry to and from a battery-powered vehicle allowing much greater lateral maneuverability relative to its support ship than a conventional ROV. During PS86, dives conducted in the Arctic Ocean (typical water depths ~4000m) were completed in >80% ice cover beneath multi-year ice that was typically 2-4m thick (increasing to depths of up to 20m beneath ridges). Dives extended up to 800m away from the ship and, over dive durations of approximately 5 hours each, covered survey tracklines of up to 3.7km at depths varying from "landing" on the underside of the sea-ice to maximum depths of 45m to conduct upward looking multibeam sonar mapping. Ultimately, the vehicle will be capable of both AUV and ROV mode operations at ranges of 10-20km away from the support ship and at up to 2000m water depth (including seafloor as well as under ice operations). During the current cruise, the following major science suites were utilized to prove a range of scientific capabilities of the vehicle in ice-covered oceans: multibeam mapping of rugged topography beneath multi-year sea-ice; video- and digital still photography of the under side of the ice, biota associated with the ice-water interface (algal material) and abundant fauna in the immediately underlying water column (ctenophores, larvaceans, copepods were all notable for their abundance in our study site over the Gakkel Ridge near 83N, 6W). Other scientific activities included: vertical profiles combining CTD data with a suite of biosensors to investigate the structure of primary productivity and biogeochemical cycling in minimally distrubed areas of the sunlit under-ice water column, revealing high stratification associated with

  18. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    Science.gov (United States)

    Coupel, P.; Jin, H. Y.; Ruiz-Pino, D.; Chen, J. F.; Lee, S. H.; Li, H. L.; Rafizadeh, M.; Garçon, V.; Gascard, J. C.

    2011-07-01

    A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA) ocean during a year of exceptional ice retreat (August-September 2008). This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC) and taxonomy (microscopy) acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N) to extreme high latitudes over the Alpha Ridge (86° N) encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin. Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1-5 mg m-3) dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (poverty (Canadian Basin) and the richness (Chukchi shelf) of the WA, we explore the role of the nutrient-rich Pacific Waters, the bathymetry and two characteristics linked to the intense ice retreat: the stratification and the Surface Freshwater Layer (SFL). The freshwater accumulation induced a strong stratification limiting the nutrient input from the subsurface Pacific waters. This results in a biomass impoverishment of the well-lit layer and compels the phytoplankton to grow in subsurface. The phytoplankton distribution in the Chukchi Borderland and north Canadian Basin, during the summer of exceptional ice retreat (2008), suggested when compared to in-situ data from a more ice covered year (1994), recent changes with a decrease of the phytoplankton abundance while averaged biomass was similar. The 2008 obtained phytoplankton data in the WA provided a state of the ecosystem which

  19. Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model

    Directory of Open Access Journals (Sweden)

    M. Steinacher

    2009-04-01

    Full Text Available Ocean acidification from the uptake of anthropogenic carbon is simulated for the industrial period and IPCC SRES emission scenarios A2 and B1 with a global coupled carbon cycle-climate model. Earlier studies identified seawater saturation state with respect to aragonite, a mineral phase of calcium carbonate, as a key variable governing impacts on corals and other shell-forming organisms. Globally in the A2 scenario, water saturated by more than 300%, considered suitable for coral growth, vanishes by 2070 AD (CO2≈630 ppm, and the ocean volume fraction occupied by saturated water decreases from 42% to 25% over this century. The largest simulated pH changes worldwide occur in Arctic surface waters, where hydrogen ion concentration increases by up to 185% (ΔpH=−0.45. Projected climate change amplifies the decrease in Arctic surface mean saturation and pH by more than 20%, mainly due to freshening and increased carbon uptake in response to sea ice retreat. Modeled saturation compares well with observation-based estimates along an Arctic transect and simulated changes have been corrected for remaining model-data differences in this region. Aragonite undersaturation in Arctic surface waters is projected to occur locally within a decade and to become more widespread as atmospheric CO2 continues to grow. The results imply that surface waters in the Arctic Ocean will become corrosive to aragonite, with potentially large implications for the marine ecosystem, if anthropogenic carbon emissions are not reduced and atmospheric CO2 not kept below 450 ppm.

  20. Hydrographic changes in the Lincoln Sea in the Arctic Ocean with focus on an upper ocean freshwater anomaly between 2007 and 2010

    Science.gov (United States)

    Steur, L.; Steele, M.; Hansen, E.; Morison, J.; Polyakov, I.; Olsen, S. M.; Melling, H.; McLaughlin, F. A.; Kwok, R.; Smethie, W. M.; Schlosser, P.

    2013-09-01

    Hydrographic data from the Arctic Ocean show that freshwater content in the Lincoln Sea, north of Greenland, increased significantly from 2007 to 2010, slightly lagging changes in the eastern and central Arctic. The anomaly was primarily caused by a decrease in the upper ocean salinity. In 2011 upper ocean salinities in the Lincoln Sea returned to values similar to those prior to 2007. Throughout 2008-2010, the freshest surface waters in the western Lincoln Sea show water mass properties similar to fresh Canada Basin waters north of the Canadian Arctic Archipelago. In the northeastern Lincoln Sea fresh surface waters showed a strong link with those observed in the Makarov Basin near the North Pole. The freshening in the Lincoln Sea was associated with a return of a subsurface Pacific Water temperature signal although this was not as strong as observed in the early 1990s. Comparison of repeat stations from the 2000s with the data from the 1990s at 65°W showed an increase of the Atlantic temperature maximum which was associated with the arrival of warmer Atlantic water from the Eurasian Basin. Satellite-derived dynamic ocean topography of winter 2009 showed a ridge extending parallel to the Canadian Archipelago shelf as far as the Lincoln Sea, causing a strong flow toward Nares Strait and likely Fram Strait. The total volume of anomalous freshwater observed in the Lincoln Sea and exported by 2011 was close to 1100±250km3, approximately 13% of the total estimated FW increase in the Arctic in 2008.

  1. A tale of two basins: An integrated physical and biological perspective of the deep Arctic Ocean

    Science.gov (United States)

    Bluhm, B. A.; Kosobokova, K. N.; Carmack, E. C.

    2015-12-01

    This review paper integrates the current knowledge, based on available literature, on the physical and biological conditions of the Amerasian and Eurasian basins (AB, EB) of the deep Arctic Ocean (AO) in a comparative fashion. The present day (Holocene) AO is a mediterranean sea that is roughly half continental shelf and half basin and ridge complex. Even more recently it is roughly two thirds seasonally and one third perennially ice-covered, thus now exposing a portion of basin waters to sunlight and wind. Basin boundaries and submarine ridges steer circulation pathways in overlying waters and limit free exchange in deeper waters. The AO is made integral to the global ocean by the Northern Hemisphere Thermohaline Circulation (NHTC) which drives Pacific-origin water (PW) through Bering Strait into the Canada Basin, and counter-flowing Atlantic-origin water (AW) through Fram Strait and across the Barents Sea into the Nansen Basin. As a framework for biogeography within the AO, four basic, large-scale circulation systems (with L > 1000 km) are noted; these are: (1) the large scale wind-driven circulation which forces the cyclonic Trans-Polar Drift from Siberia to the Fram Strait and the anticyclonic Beaufort Gyre in the southern Canada Basin; (2) the circulation of waters that comprise the halocline complex, composed largely of waters of Pacific and Atlantic origin that are modified during passage over the Bering/Chukchi and Barents/Siberian shelves, respectively; (3) the topographically-trapped Arctic Circumpolar Boundary Current (ACBC) which carries AW cyclonically around the boundaries of the entire suite of basins, and (4) the very slow exchange of Arctic Ocean Deep Waters. Within the basin domain two basic water mass assemblies are observed, the difference between them being the absence or presence of PW sandwiched between Arctic Surface Waters (ASW) above and the AW complex below; the boundary between these domains is the Atlantic/Pacific halocline front. Both

  2. IODP Expedition 302, Arctic Coring Expedition (ACEX: A First Look at the Cenozoic Paleoceanography of the Central Arctic Ocean

    Directory of Open Access Journals (Sweden)

    the IODP Expedition 302 Scientists

    2005-09-01

    Full Text Available Introduction The behavior and inf luence of the A rct ic Oceanthroughout the course of the global Cenozoic climateevolution have been virtually unknown. Only the uppermostfew meters of the Arctic’s sediment record, representingHolocene and late Pleistocene times, have been retrievedfrom ridges through a limited number of short piston,gravity, and box cores. Even less of the thick sedimentsequences, ~6 km in the Canada Basin and ~3 km in theNansen Basin(Grantz et al., 1990; Jokat et al., 1995, restingon the Arctic Ocean’s abyssal plains, have been cored.Prior to the Arctic Coring Expedition (ACEX, informationon Neogene or Paleogene conditions in the central Arcticwas limited to a 1.6-m interval in a 3.6-m-long T-3 gravitycore raised from the Alpha Ridge (Clark, 1974, providingthe sole evidence for marine conditions no older than themiddle Eocene in the central Arctic (Bukry, 1984.

  3. Pathways of PFOA to the Arctic: variabilities and contributions of oceanic currents and atmospheric transport and chemistry sources

    Directory of Open Access Journals (Sweden)

    I. Stemmler

    2010-05-01

    Full Text Available Perfluorooctanoic acid (PFOA and other perfluorinated compounds are industrial chemicals in use since decades which resist degradation in the environment and seem to accumulate in polar regions. Transport of PFOA was modeled using a spatially resolved global multicompartment model including fully coupled three-dimensional ocean and atmosphere general circulation models, and two-dimensional top soil, vegetation surfaces, and sea ice compartments. In addition to primary emissions, the formation of PFOA in the atmosphere from degradation of 8:2 fluorotelomer alcohol was included as a PFOA source. Oceanic transport, delivered 14.8±5.0 (8–23 t a−1 to the Arctic, strongly influenced by changes in water transport, which determined its interannual variability. This pathway constituted the dominant source of PFOA to the Arctic. Formation of PFOA in the atmosphere lead to episodic transport events (timescale of days into the Arctic with small spatial extent. Deposition in the polar region was found to be dominated by wet deposition over land, and shows maxima in boreal winter. The total atmospheric deposition of PFOA in the Arctic in the 1990s was ≈1 t a−1, much higher than previously estimated, and is dominated by primary emissions rather than secondarily formed.

  4. The melting sea ice of Arctic polar cap in the summer solstice month and the role of ocean

    Science.gov (United States)

    Lee, S.; Yi, Y.

    2014-12-01

    The Arctic sea ice is becoming smaller and thinner than climatological standard normal and more fragmented in the early summer. We investigated the widely changing Arctic sea ice using the daily sea ice concentration data. Sea ice data is generated from brightness temperature data derived from the sensors: Defense Meteorological Satellite Program (DMSP)-F13 Special Sensor Microwave/Imagers (SSM/Is), the DMSP-F17 Special Sensor Microwave Imager/Sounder (SSMIS) and the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) instrument on the NASA Earth Observing System (EOS) Aqua satellite. We tried to figure out appearance of arctic sea ice melting region of polar cap from the data of passive microwave sensors. It is hard to explain polar sea ice melting only by atmosphere effects like surface air temperature or wind. Thus, our hypothesis explaining this phenomenon is that the heat from deep undersea in Arctic Ocean ridges and the hydrothermal vents might be contributing to the melting of Arctic sea ice.

  5. Late Quaternary sea-ice history of northern Fram Strait/Arctic Ocean

    Science.gov (United States)

    Kremer, Anne; Stein, Rüdiger; Fahl, Kirsten; Matthießen, Jens; Forwick, Matthias; O'Regan, Matt

    2016-04-01

    One of the main characteristics of the Arctic Ocean is its seasonal to perennial sea-ice cover. Variations of sea-ice conditions affect the Earth's albedo, primary production, rate of deep-water etc.. During the last decades, a drastic decrease in sea ice has been recorded, and the causes of which, i.e., natural vs. anthropogenic forcings, and their relevance within the global climate system, are subject of intense scientific and societal debate. In this context, records of past sea-ice conditions going beyond instrumental records are of major significance. These records may help to better understand the processes controlling natural sea-ice variability and to improve models for forecasts of future climatic conditions. During RV Polarstern Cruise PS92 in summer 2015, a 860 cm long sediment core (PS92/039-2) was recovered from the eastern flank of Yermak Plateau north of the Svalbard archipelago (Peeken, 2015). Based on a preliminary age model, this sediment core probably represents the time interval from MIS 6 to MIS 1. This core, located close to the modern summer ice edge, has been selected for reconstruction of past Arctic sea-ice variability based on specific biomarkers. In this context, we have determined the ice-algae-derived sea-ice proxy IP25 (Belt et al., 2007), in combination with other biomarkers indicative for open-water conditions (cf., Müller et al., 2009, 2011). Furthermore, organic carbon fluxes were differentiated using specific biomarkers indicative for marine primary production (brassicasterol, dinosterol) and terrigenous input (campesterol, β-sitosterol). In this poster, preliminary results of our organic-geochemical and sedimentological investigations are presented. Distinct fluctuations of these biomarkers indicate several major, partly abrupt changes in sea-ice cover in the Yermak Plateau area during the late Quaternary. These changes are probably linked to changes in the inflow of Atlantic Water along the western coastline of Svalbard into

  6. Modeling the Oceanic Exchanges Across the Main Arctic Gateways with Emphasis on Atlantic Water and Its Impact on Sea Ice and Climate

    Science.gov (United States)

    Maslowski, Wieslaw; Osinski, Robert; Clement Kinney, Jaclyn; Roberts, Andrew; DiMaggio, Dominic; Craig, Anthony

    2016-04-01

    Estimation of the oceanic budgets of total mass and property exchanges across the main Arctic gateways is challenging from both observational and modeling points of view. While data are insufficient to close such budgets, ocean models commonly struggle with representing transports through the narrow and shallow gates (i.e. Bering Strait and the Canadian Arctic Archipelago) as well as exchanges across Fram Strait or the Barents Sea. Uncertainties in observational constraints at those gates are part of the modeling problems. Yet, realistic model representation of oceanic fluxes, including those associated with Atlantic water, is critical to understanding, simulation and prediction of their impact on the sea ice cover and related feedbacks to the atmosphere and climate. We analyze results from several multi-decadal simulations of the Regional Arctic System Model (RASM) focusing on oceanic fluxes across the Arctic gateways. RASM is a limited-area, process-resolving, coupled atmosphere - ice - ocean - land model that includes the ocean and sea ice models, which are regionally configured versions of those used in the Community Earth System Model (CESM): the Los Alamos Community Ice Model (CICE) and Parallel Ocean Program (POP). The Weather Research and Forecasting (WRF) is used for an atmospheric model, with land surface processes and hydrology represented by the Variable Infiltration Capacity (VIC) model. RASM's pan-Arctic domain covers the entire Northern Hemisphere marine cryosphere, terrestrial drainage and, major inflow/outflow channels to/from the Arctic Ocean, with large portions of the subpolar oceans to allow optimal simulation of the oceanic pathways into and from the central Arctic. The ocean model uses 45 vertical z-coordinate levels and 1/12° or 1/48° rotated sphere meshes with an equator extending across the North Pole, resulting in ~9.3km or 2.4km resolution in the Arctic Ocean, and minimal area distortion near the boundaries. The main objective of this

  7. Light absorption and partitioning in Arctic Ocean surface waters: impact of multi year ice melting

    Directory of Open Access Journals (Sweden)

    S. Bélanger

    2013-03-01

    Full Text Available Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie river-influenced waters and polar mixed layer waters. We found that melting multi-year ice released significant amount of non-algal particulates (NAP near the sea surface relative to sub-surface waters. NAP absorption coefficients at 440 nm (aNAP(440 immediately below the sea surface (0- were on average 3-fold (up to 10-fold higher compared to sub-surface values measured at 2–3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR by ~6% and ~8%, respectively, relative to a fully homogenous water column with low particles concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400–550 nm. These results highlight the impact of melt water on the concentration of particles at sea surface, and the need for considering nonuniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM photobleaching.

  8. Light absorption and partitioning in Arctic Ocean surface waters: impact of multiyear ice melting

    Directory of Open Access Journals (Sweden)

    S. Bélanger

    2013-10-01

    Full Text Available Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie River-influenced waters and polar mixed layer waters. We found that melting multiyear ice released significant amount of non-algal particulates (NAP near the sea surface relative to subsurface waters. NAP absorption coefficients at 440 nm (aNAP(440 immediately below the sea surface were on average 3-fold (up to 10-fold higher compared to subsurface values measured at 2–3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR by ∼6 and ∼8%, respectively, relative to a fully homogenous water column with low particle concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400–550 nm. These results highlight the impact of meltwater on the concentration of particles at sea surface, and the need for considering non-uniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV (ultraviolet domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM (particulate organic matter photobleaching.

  9. Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter.

    Science.gov (United States)

    Last, Kim S; Hobbs, Laura; Berge, Jørgen; Brierley, Andrew S; Cottier, Finlo

    2016-01-25

    In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological migration have historically been considered non-existent [1]. However, diel vertical migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as yet, unexplained. Here, we present evidence of an unexpected uniform behavior across the entire Arctic, in fjord, shelf, slope and open sea, where vertical migrations of zooplankton are driven by lunar illumination. A shift from solar-day (24-hr period) to lunar-day (24.8-hr period) vertical migration takes place in winter when the moon rises above the horizon. Further, mass sinking of zooplankton from the surface waters and accumulation at a depth of ∼50 m occurs every 29.5 days in winter, coincident with the periods of full moon. Moonlight may enable predation of zooplankton by carnivorous zooplankters, fish, and birds now known to feed during the polar night [4]. Although primary production is almost nil at this time, lunar vertical migration (LVM) may facilitate monthly pulses of carbon remineralization, as they occur continuously in illuminated mesopelagic systems [5], due to community respiration of carnivorous and detritivorous zooplankton. The extent of LVM during the winter suggests that the behavior is highly conserved and adaptive and therefore needs to be considered as "baseline" zooplankton activity in a changing Arctic ocean [6-9]. VIDEO ABSTRACT.

  10. The Arctic Summer Cloud Ocean Study (ASCOS) : Overview and experimental design

    NARCIS (Netherlands)

    Tjernström, M.; Leck, C.; Birch, C.E.; Bottenheim, J.W.; Brooks, B.J.; Brooks, I.M.; Bäcklin, L.; Chang, R.Y.W.; Leeuw, G. de; Liberto, L. di; Rosa, S. de la; Granath, E.; Graus, M.; Hansel, A.; Heintzenberg, J.; Held, A.; Hind, A.; Johnston, P.; Knulst, J.; Martin, M.; Matrai, P.A.; Mauritsen, T.; Müller, M.; Norris, S.J.; Orellana, M.V.; Orsini, D.A.; Paatero, J.; Persson, P.O.G.; Gao, Q.; Rauschenberg, C.; Ristovski, Z.; Sedlar, J.; Shupe, M.D.; Sierau, B.; Sirevaag, A.; Sjogren, S.; Stetzer, O.; Swietlicki, E.; Szczodrak, M.; Vaattovaara, P.; Wahlberg, N.; Westberg, M.; Wheeler, C.R.

    2014-01-01

    The climate in the Arctic is changing faster than anywhere else on earth. Poorly understood feedback processes relating to Arctic clouds and aerosol-cloud interactions contribute to a poor understanding of the present changes in the Arctic climate system, and also to a large spread in projections of

  11. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values.

  12. Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

    Science.gov (United States)

    Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

    2010-01-01

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

  13. Inter-comparison of state-of-the-art MSS and geoid models in the Arctic Ocean

    DEFF Research Database (Denmark)

    Skourup, Henriette; Farrell, Sinead; Hendricks, Stefan

    State-of-the-art Arctic Ocean mean sea surface (MSS) and geoid models are used to support sea ice freeboard estimation from satellite altimeters, and for oceanographic studies. However, errors in a given model in the high frequency domain, e.g. due to unresolved gravity features, can result...... in errors in the estimated freeboard heights, especially in areas with a sparse lead distribution in consolidated ice conditions. Additionally these errors can impact ocean geostrophic current estimates and remaining biases in the models may impact longer-term, multi-sensor oceanographic time-series of sea...... level change.This study, part of the ESA CryoVal Sea Ice project, focuses on an inter-comparison of various state-of-the-art Arctic MSS models (UCL13/DTU13/ICEn) and commonly-used geoid models (EGM08). We show improved definition of gravity features, such as the Gakkel ridge, in the latest MSS models...

  14. Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic Ocean.

    Science.gov (United States)

    Polyakov, Igor V; Pnyushkov, Andrey V; Alkire, Matthew B; Ashik, Igor M; Baumann, Till M; Carmack, Eddy C; Goszczko, Ilona; Guthrie, John; Ivanov, Vladimir V; Kanzow, Torsten; Krishfield, Richard; Kwok, Ronald; Sundfjord, Arild; Morison, James; Rember, Robert; Yulin, Alexander

    2017-04-06

    Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin. This encroaching "atlantification" of the Eurasian Basin represents an essential step toward a new Arctic climate state, with a substantially greater role for Atlantic inflows.

  15. Widespread Pleistocene submarine landslides and erosion on the Lomonosov Ridge (central Arctic Ocean)

    Science.gov (United States)

    Niessen, Frank; Stein, Rüdiger; Sauermilch, Isabel; Jensen, Laura; Jokat, Wilfried; Geissler, Wolfram; Gebhardt, Catalina

    2016-04-01

    The Lomonosov Ridge is seen as a relict of continental crust, which drifted from its original Eurasian shelf-edge location into the central Arctic Ocean during the formation of the Eurasian Basin by sea-floor spreading. With a total length of 1800 km, widths between 50 and 220 km and submarine elevations of 3 km above the abyssal plain the Lomonosov Ridge has dimensions of an Alpine mountain chain. Seismic lines indicate that large areas of the ridge are covered by well-stratified undisturbed Cenozoic sediments of more than 400 m in thickness. This may suggest that the ridge is in a relatively stable tectonic setting and exposed to hemi-pelagic deposition over long time scales. However, there is now a growing number of evidence that the crest and upper slopes of the ridge are characterized by widespread mass wasting. Kristoffersen et al. (2007) described major sediment disruptions on the slopes associated with slide scars on the crest of the Lomonosov Ridge between 87°30' and 88°N as a local phenomenon. Since the expedition of RV "Polarstern" in 2014, which explored the Lomonosov Ridge from near the pole to the Eurasian margin, we now know that similar mass wasting has been common probably along the entire ridge. Detailed bathymetric mapping between 81° and 84°N exhibit numerous amphitheatre-like slide scars, under which large amounts of Cenozoic sediments were remobilized into mass-wasting features on both the Makarov and Amundsen sides of the ridge. Sub-bottom seismic profiling discovered at least three generations of debris-flow deposits near the ridge, which were generated by the slides. Underneath the slide scars escarpments of up to 400 m in height were formed, which exposed Cenozoic sediments at the sea floor. Sediment cores from these locations recovered unconformities related to the youngest erosional event, which are overlain by undisturbed sediments accumulated during Marine Isotope Stages (MIS) 1 to 6. An age of MIS-6 is also suggested for the

  16. Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992–2009; sources and atmospheric flux

    NARCIS (Netherlands)

    Lorenson, T.D.; Greinert, J.; Coffin, R.B.

    2016-01-01

    Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of theArctic Ocean during 11 surveys spanning the years of 1992–1995 and 2009. During ice-free periods, methaneflux from the Beaufort shelf varies from 0.14 mg CH4 m22 d21 to 0.43 mg CH4 m22 d21. Maximum f

  17. Characteristics of Arctic Ocean ice determined from SMMR data for 1979 - Case studies in the seasonal sea ice zone

    Science.gov (United States)

    Anderson, M. R.; Crane, R. G.; Barry, R. G.

    1985-01-01

    Sea ice data derived from the Scanning Multichannel Microwave Radiometer are examined for sections of the Arctic Ocean during early summer 1979. The temporary appearance of spuriously high multiyear ice fractions in the seasonal ice zones of the Kara and Barents Seas is a result of surface melt phenomena and the relative responses of the different channels to these effects. These spurious signatures can provide early identification of melt onset and additional information on surface characteristics.

  18. Net primary productivity estimates and environmental variables in the Arctic Ocean: An assessment of coupled physical-biogeochemical models

    OpenAIRE

    Lee, Younjoo J.; Matrai, Patricia A.; Friedrichs, Marjorie A. M; Vincent S. Saba; Aumont, Olivier; Babin, Marcel; Buitenhuis, Erik T.; Chevallier, Matthieu; de Mora, Lee; Dessert, Morgane; Dunne, John P.; Ellingsen, Ingrid; Feldman, Doron; Frouin, Robert; Gehlen, Marion

    2016-01-01

    The relative skill of 21 regional and global biogeochemical models was assessed in terms of how well the models reproduced observed net primary productivity (NPP) and environmental variables such as nitrate concentration (NO3), mixed layer depth (MLD), euphotic layer depth (Zeu), and sea ice concentration, by comparing results against a newly updated, quality-controlled in situ NPP database for the Arctic Ocean (1959-2011). The models broadly captured the spatial features of integrated NPP (i...

  19. Anthropogenic {sup 129}I in the North Pacific, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, H., E-mail: hnagai@chs.nihon-u.ac.jp [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Hasegawa, A. [Graduate School of Integrated Basic Sciences, Nihon University, Tokyo 156-8550 (Japan); Yamagata, T. [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Kumamoto, Y.; Nishino, S. [Japan Agency for Marine-Earth Science and Technology, Kanagawa 237-0061 (Japan); Matsuzaki, H. [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo 113-0032 (Japan)

    2015-10-15

    Most of anthropogenic {sup 129}I in marine environment are due to discharge from the nuclear fuel reprocessing facilities at Sellafield (U.K.) and La Hague (France) for past few decades. The discharge raised {sup 129}I concentration in seawaters in the North Atlantic and Arctic Oceans to more than 10{sup 9} atoms L{sup −1}, which is two orders of magnitude higher than that in other region. Recently, in March 2011, a large quantity of {sup 129}I was released into the western North Pacific due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. To evaluate the influence of these events, we have measured {sup 129}I concentration in seawaters in the northern North Pacific Ocean, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013. The {sup 129}I concentrations were 1.0–1.8 × 10{sup 7} atoms L{sup −1} in the surface waters in the vicinity of 47°N 150°E–130°W North Pacific Ocean, Bering Sea, and Chukchi Sea (<74°N), which are equal to or lower than the {sup 129}I concentration level in surface water in the North Pacific Ocean before the F1NPP accident. The vertical profiles in the North Pacific were almost same as that observed in the western North Pacific before the F1NPP accident. The {sup 129}I distribution in seawater in the North Pacific to the Chukchi Sea revealed no significant increase of {sup 129}I concentration caused by the F1NPP accident. The {sup 129}I concentrations were 13–14 × 10{sup 7} atoms L{sup −1} in surface waters and 80 × 10{sup 7} atoms L{sup −1} at depths of 300 and 800 m in the Arctic Ocean.

  20. Biogeography of heterotrophic flagellate populations indicates the presence of generalist and specialist taxa in the Arctic Ocean.

    Science.gov (United States)

    Thaler, Mary; Lovejoy, Connie

    2015-03-01

    Heterotrophic marine flagellates (HF) are ubiquitous in the world's oceans and represented in nearly all branches of the domain Eukaryota. However, the factors determining distributions of major taxonomic groups are poorly known. The Arctic Ocean is a good model environment for examining the distribution of functionally similar but phylogenetically diverse HF because the physical oceanography and annual ice cycles result in distinct environments that could select for microbial communities or favor specific taxa. We reanalyzed new and previously published high-throughput sequencing data from multiple studies in the Arctic Ocean to identify broad patterns in the distribution of individual taxa. HF accounted for fewer than 2% to over one-half of the reads from the water column and for up to 60% of reads from ice, which was dominated by Cryothecomonas. In the water column, many HF phylotypes belonging to Telonemia and Picozoa, uncultured marine stramenopiles (MAST), and choanoflagellates were geographically widely distributed. However, for two groups in particular, Telonemia and Cryothecomonas, some species level taxa showed more restricted distributions. For example, several phylotypes of Telonemia favored open waters with lower nutrients such as the Canada Basin and offshore of the Mackenzie Shelf. In summary, we found that while some Arctic HF were successful over a range of conditions, others could be specialists that occur under particular conditions. We conclude that tracking species level diversity in HF not only is feasible but also provides a potential tool for understanding the responses of marine microbial ecosystems to rapidly changing ice regimes.

  1. Climate relevant trace gases (N2O and CH4) in the Eurasian Basin (Arctic Ocean)

    Science.gov (United States)

    Verdugo, Josefa; Damm, Ellen; Snoeijs, Pauline; Díez, Beatriz; Farías, Laura

    2016-11-01

    The concentration of greenhouse gases, including nitrous oxide (N2O), methane (CH4), and compounds such as total dimethylsulfoniopropionate (DMSPt), along with other oceanographic variables were measured in the ice-covered Arctic Ocean within the Eurasian Basin (EAB). The EAB is affected by the perennial ice-pack and has seasonal microalgal blooms, which in turn may stimulate microbes involved in trace gas cycling. Data collection was carried out on board the LOMROG III cruise during the boreal summer of 2012. Water samples were collected from the surface to the bottom layer (reaching 4300 m depth) along a South-North transect (SNT), from 82.19°N, 8.75°E to 89.26°N, 58.84°W, crossing the EAB through the Nansen and Amundsen Basins. The Polar Mixed Layer and halocline waters along the SNT showed a heterogeneous distribution of N2O, CH4 and DMSPt, fluctuating between 42-111 and 27-649% saturation for N2O and CH4, respectively; and from 3.5 to 58.9 nmol L-1 for DMSPt. Spatial patterns revealed that while CH4 and DMSPt peaked in the Nansen Basin, N2O was higher in the Amundsen Basin. In the Atlantic Intermediate Water and Arctic Deep Water N2O and CH4 distributions were also heterogeneous with saturations between 52% and 106% and 28% and 340%, respectively. Remarkably, the Amundsen Basin contained less CH4 than the Nansen Basin and while both basins were mostly under-saturated in N2O. We propose that part of the CH4 and N2O may be microbiologically consumed via methanotrophy, denitrification, or even diazotrophy, as intermediate and deep waters move throughout EAB associated with the overturning water mass circulation. This study contributes to baseline information on gas distribution in a region that is increasingly subject to rapid environmental changes, and that has an important role on global ocean circulation and climate regulation.

  2. Searching for the Lost Jurassic and Cretaceous Ocean Basins of the Circum-Arctic Linking Plate Models and Seismic Tomography

    Science.gov (United States)

    Shephard, G. E.; Müller, R.

    2012-12-01

    The tectonic evolution of the circum-Arctic since the breakup of Pangea involves the opening and closing of ocean basins including the Oimyakon, Angayucham, South Anuyi, Amerasia and Eurasia basins. The time-dependent configurations and kinematic history of the basins, adjacent continental terranes, and subduction zones involved are not well understood, and many published tectonic models for particular regions are inconsistent with models for adjacent areas. The age, location, geometry and convergence rates of the subduction zones associated with these ancient ocean basins since at least the Late Jurassic have implications for mantle structure, which can be used as an additional constraint for building plate and plate boundary models. Here we integrate an analysis of both surface and deep mantle observations back to 200 Ma. Based on a digitized set of tectonic features with time-dependent rotational histories we present a refined plate model with topologically closed plate polygons for the circum-Arctic with particular focus on the northern Pacific, Siberian and Alaskan margins (Fig 1). We correlate the location, geometry and timing of subduction zones with associated seismic velocities anomalies from global P and S wave tomography models across different depths. We design a plate model that best matches slabs imaged in seismic tomography in an iterative fashion. This match depends on a combination of relative and absolute plate motions. Therefore we test two end-member absolute plate motion models, evaluating a paleomagnetic model and a model based on hotspot tracks and large igneous provinces. This method provides a novel approach to deciphering the Arctic tectonic history in a global context. Fig 1:Plate reconstruction at 200Ma and 140Ma, visualized using GPlates software. Present-day topography raster (ETOPO2) segmented into major tectonic elements of the circum-Arctic. Plate boundaries delineated in black and selected subduction and arc features labeled in

  3. Observed microphysical changes in Arctic mixed-phase clouds when transitioning from sea-ice to open ocean

    Science.gov (United States)

    Young, Gillian; Jones, Hazel M.; Crosier, Jonathan; Bower, Keith N.; Darbyshire, Eoghan; Taylor, Jonathan W.; Liu, Dantong; Allan, James D.; Williams, Paul I.; Gallagher, Martin W.; Choularton, Thomas W.

    2016-04-01

    The Arctic sea-ice is intricately coupled to the atmosphere[1]. The decreasing sea-ice extent with the changing climate raises questions about how Arctic cloud structure will respond. Any effort to answer these questions is hindered by the scarcity of atmospheric observations in this region. Comprehensive cloud and aerosol measurements could allow for an improved understanding of the relationship between surface conditions and cloud structure; knowledge which could be key in validating weather model forecasts. Previous studies[2] have shown via remote sensing that cloudiness increases over the marginal ice zone (MIZ) and ocean with comparison to the sea-ice; however, to our knowledge, detailed in-situ data of this transition have not been previously presented. In 2013, the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign was carried out in the vicinity of Svalbard, Norway to collect in-situ observations of the Arctic atmosphere and investigate this issue. Fitted with a suite of remote sensing, cloud and aerosol instrumentation, the FAAM BAe-146 aircraft was used during the spring segment of the campaign (Mar-Apr 2013). One case study (23rd Mar 2013) produced excellent coverage of the atmospheric changes when transitioning from sea-ice, through the MIZ, to the open ocean. Clear microphysical changes were observed, with the cloud liquid-water content increasing by almost four times over the transition. Cloud base, depth and droplet number also increased, whilst ice number concentrations decreased slightly. The surface warmed by ~13 K from sea-ice to ocean, with minor differences in aerosol particle number (of sizes corresponding to Cloud Condensation Nuclei or Ice Nucleating Particles) observed, suggesting that the primary driver of these microphysical changes was the increased heat fluxes and induced turbulence from the warm ocean surface as expected. References: [1] Kapsch, M.L., Graversen, R.G. and Tjernström, M. Springtime

  4. Circumpolar measurements of speciated mercury, ozone and carbon monoxide in the boundary layer of the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. Sommar

    2010-06-01

    Full Text Available Using the Swedish icebreaker Oden as a platform, continuous measurements of airborne mercury (gaseous elemental mercury (Hg0, divalent gaseous mercury species HgIIX2(g (acronym RGM and mercury attached to particles (PHg and some long-lived trace gases (carbon monoxide CO and ozone O3 were performed over the North Atlantic and the Arctic Ocean. The measurements were performed for nearly three months (July–September 2005 during the Beringia 2005 expedition (from Göteborg, Sweden via the proper Northwest Passage to the Beringia region Alaska – Chukchi Penninsula – Wrangel Island and in-turn via a north-polar transect to Longyearbyen, Spitsbergen. The Beringia 2005 expedition was the first time that these species have been measured during summer over the Arctic Ocean going from 60° to 90° N.

    During the North Atlantic transect, concentration levels of Hg0, CO and O3 were measured comparable to typical levels for the ambient mid-hemispheric average. However, a rapid increase of Hg0 in air and surface water was observed when entering the ice-covered waters of the Canadian Arctic archipelago. Large parts of the measured waters were supersaturated with respect to Hg0, reflecting a strong disequilibrium. Heading through the sea ice of the Arctic Ocean, a fraction of the strong Hg0 pulse in the water was transferred with some time-delay into the air samples collected ~20 m above sea level. Several episodes of elevated Hg0 in air were encountered along the sea ice route with higher mean concentration (1.81±0.43 ng m−3 compared to the marine boundary layer over ice-free Arctic oceanic waters (1.55±0.21 ng m−3. In addition, the bulk of the variance in the temporal series of Hg0 concentrations was observed during July. The Oden Hg0 observations compare in this aspect very favourably

  5. Seasonality and long term trends in dissolved carbon export from large rivers to the Arctic Ocean, and potential effects on coastal ocean acidification (Invited)

    Science.gov (United States)

    Tank, S. E.; Kokelj, S. V.; Raymond, P. A.; Striegl, R. G.; McClelland, J. W.; Holmes, R. M.; Spencer, R. G.

    2013-12-01

    Large Arctic rivers show marked seasonality in constituent flux as a result of variations in flowpath throughout the yearly cycle. Here, we use measurements collected from the mouths of the six largest rivers draining to the Arctic Ocean to explore seasonal variation in dissolved inorganic and dissolved organic carbon (DIC, DOC) flux, and the effect of this flux on nearshore ocean processes. This work uses data from the Yukon and Mackenzie Rivers in North America, and the Kolyma, Lena, Yenisey, and Ob' in Siberia. Mean monthly concentrations of riverine DIC vary synchronously across all rivers, peaking under ice and reaching a low point immediately after the spring freshet. Monthly climatologies for DIC, in addition to similarly constructed climatologies for Ca2+, show that the input of riverwater universally causes aragonite to be undersaturated in riverine-influenced nearshore regions, with an effect that is greater for the Siberian coast than for western North America, and greater in the spring-winter than in the late summer and fall. Because seasonal trends and geographic variation in DOC concentration are opposite to that for DIC in these large rivers, degradation of DOC to CO2 in the nearshore Arctic should accentuate seasonal and spatial patterns in aragonite undersaturation in Arctic coastal regions. Datasets that extend DIC and DOC concentration measurements back to the early 1970's (DIC) and early 1980's (DOC) near the mouth of the Mackenzie River in the western Canadian Arctic indicate that the summertime concentration and flux of these constituents has been increasing over time in this region. While evidence from other regions of the pan-Arctic, and data gathered from smaller sub-catchment studies indicate that this trend is not universal for DOC, there is growing evidence for a consistent increase in summertime DIC flux across both time and gradients of decreasing permafrost extent. These changes, in turn, could have broad implications for both

  6. Nitrification and its influence on biogeochemical cycles from the equatorial Pacific to the Arctic Ocean.

    Science.gov (United States)

    Shiozaki, Takuhei; Ijichi, Minoru; Isobe, Kazuo; Hashihama, Fuminori; Nakamura, Ken-Ichi; Ehama, Makoto; Hayashizaki, Ken-Ichi; Takahashi, Kazutaka; Hamasaki, Koji; Furuya, Ken

    2016-09-01

    We examined nitrification in the euphotic zone, its impact on the nitrogen cycles, and the controlling factors along a 7500 km transect from the equatorial Pacific Ocean to the Arctic Ocean. Ammonia oxidation occurred in the euphotic zone at most of the stations. The gene and transcript abundances for ammonia oxidation indicated that the shallow clade archaea were the major ammonia oxidizers throughout the study regions. Ammonia oxidation accounted for up to 87.4% (average 55.6%) of the rate of nitrate assimilation in the subtropical oligotrophic region. However, in the shallow Bering and Chukchi sea shelves (bottom ⩽67 m), the percentage was small (0-4.74%) because ammonia oxidation and the abundance of ammonia oxidizers were low, the light environment being one possible explanation for the low activity. With the exception of the shallow bottom stations, depth-integrated ammonia oxidation was positively correlated with depth-integrated primary production. Ammonia oxidation was low in the high-nutrient low-chlorophyll subarctic region and high in the Bering Sea Green Belt, and primary production in both was influenced by micronutrient supply. An ammonium kinetics experiment demonstrated that ammonia oxidation did not increase significantly with the addition of 31-1560 nm ammonium at most stations except in the Bering Sea Green Belt. Thus, the relationship between ammonia oxidation and primary production does not simply indicate that ammonia oxidation increased with ammonium supply through decomposition of organic matter produced by primary production but that ammonia oxidation might also be controlled by micronutrient availability as with primary production.

  7. Late Paleocene Arctic Ocean shallow-marine temperatures from mollusc stable isotopes

    Science.gov (United States)

    Bice, Karen L.; Arthur, Michael A.; Marincovich, Louie

    1996-01-01

    Late Paleocene high-latitude (80°N) Arctic Ocean shallow-marine temperatures are estimated from molluscan δ18O time series. Sampling of individual growth increments of two specimens of the bivalve Camptochlamys alaskensis provides a high-resolution record of shell stable isotope composition. The heavy carbon isotopic values of the specimens support a late Paleocene age for the youngest marine beds of the Prince Creek Formation exposed near Ocean Point, Alaska. The oxygen isotopic composition of regional freshwater runoff is estimated from the mean δ18O value of two freshwater bivalves collected from approximately coeval fluviatile beds. Over a 30 – 34‰ range of salinity, values assumed to represent the tolerance of C. alaskensis, the mean annual shallow-marine temperature recorded by these individuals is between 11° and 22°C. These values could represent maximum estimates of the mean annual temperature because of a possible warm-month bias imposed on the average δ18O value by slowing or cessation of growth in winter months. The amplitude of the molluscan δ18O time series probably records most of the seasonality in shallow-marine temperature. The annual temperature range indicated is approximately 6°C, suggesting very moderate high-latitude marine temperature seasonality during the late Paleocene. On the basis of analogy with modern Chlamys species, C. alaskensis probably inhabited water depths of 30–50 m. The seasonal temperature range derived from δ18O is therefore likely to be damped relative to the full range of annual sea surface temperatures. High-resolution sampling of molluscan shell material across inferred growth bands represents an important proxy record of seasonality of marine and freshwater conditions applicable at any latitude. If applied to other regions and time periods, the approach used here would contribute substantially to the paleoclimate record of seasonality.

  8. Contribution of sea-ice loss to Arctic amplification is regulated by Pacific Ocean decadal variability

    Science.gov (United States)

    Screen, James A.; Francis, Jennifer A.

    2016-09-01

    The pace of Arctic warming is about double that at lower latitudes--a robust phenomenon known as Arctic amplification. Many diverse climate processes and feedbacks cause Arctic amplification, including positive feedbacks associated with diminished sea ice. However, the precise contribution of sea-ice loss to Arctic amplification remains uncertain. Through analyses of both observations and model simulations, we show that the contribution of sea-ice loss to wintertime Arctic amplification seems to be dependent on the phase of the Pacific Decadal Oscillation (PDO). Our results suggest that, for the same pattern and amount of sea-ice loss, consequent Arctic warming is larger during the negative PDO phase relative to the positive phase, leading to larger reductions in the poleward gradient of tropospheric thickness and to more pronounced reductions in the upper-level westerlies. Given the oscillatory nature of the PDO, this relationship has the potential to increase skill in decadal-scale predictability of the Arctic and sub-Arctic climate. Our results indicate that Arctic warming in response to the ongoing long-term sea-ice decline is greater (reduced) during periods of the negative (positive) PDO phase. We speculate that the observed recent shift to the positive PDO phase, if maintained and all other factors being equal, could act to temporarily reduce the pace of wintertime Arctic warming in the near future.

  9. Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Dahle, Håkon; Økland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H

    2015-07-01

    Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki's Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and hydrothermal fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of hydrothermal chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition.

  10. Microbial diversity of Loki's Castle black smokers at the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Jaeschke, A; Jørgensen, S L; Bernasconi, S M; Pedersen, R B; Thorseth, I H; Früh-Green, G L

    2012-11-01

    Hydrothermal vent systems harbor rich microbial communities ranging from aerobic mesophiles to anaerobic hyperthermophiles. Among these, members of the archaeal domain are prevalent in microbial communities in the most extreme environments, partly because of their temperature-resistant and robust membrane lipids. In this study, we use geochemical and molecular microbiological methods to investigate the microbial diversity in black smoker chimneys from the newly discovered Loki's Castle hydrothermal vent field on the Arctic Mid-Ocean Ridge (AMOR) with vent fluid temperatures of 310-320 °C and pH of 5.5. Archaeal glycerol dialkyl glycerol tetraether lipids (GDGTs) and H-shaped GDGTs with 0-4 cyclopentane moieties were dominant in all sulfide samples and are most likely derived from both (hyper)thermophilic Euryarchaeota and Crenarchaeota. Crenarchaeol has been detected in low abundances in samples derived from the chimney exterior indicating the presence of Thaumarchaeota at lower ambient temperatures. Aquificales and members of the Epsilonproteobacteria were the dominant bacterial groups detected. Our observations based on the analysis of 16S rRNA genes and biomarker lipid analysis provide insight into microbial communities thriving within the porous sulfide structures of active and inactive deep-sea hydrothermal vents. Microbial cycling of sulfur, hydrogen, and methane by archaea in the chimney interior and bacteria in the chimney exterior may be the prevailing biogeochemical processes in this system.

  11. Optimizing Ship Classification in the Arctic Ocean: A Case Study of Multi-Disciplinary Problem Solving

    Directory of Open Access Journals (Sweden)

    Mark Rahmes

    2014-08-01

    Full Text Available We describe a multi-disciplinary system model for determining decision making strategies based upon the ability to perform data mining and pattern discovery utilizing open source actionable information to prepare for specific events or situations from multiple information sources. We focus on combining detection theory with game theory for classifying ships in Arctic Ocean to verify ship reporting. More specifically, detection theory is used to determine probability of deciding if a ship or certain ship class is present or not. We use game theory to fuse information for optimal decision making on ship classification. Hierarchy game theory framework enables complex modeling of data in probabilistic modeling. However, applicability to big data is complicated by the difficulties of inference in complex probabilistic models, and by computational constraints. We provide a framework for fusing sensor inputs to help compare if the information of a ship matches its AIS reporting requirements using mixed probabilities from game theory. Our method can be further applied to optimizing other choke point scenarios where a decision is needed for classification of ground assets or signals. We model impact on decision making on accuracy by adding more parameters or sensors to the decision making process as sensitivity analysis.

  12. Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

    Directory of Open Access Journals (Sweden)

    Monique M L van Kempen

    Full Text Available In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval.

  13. Impact of ocean acidification on a key Arctic pelagic mollusc (Limacina helicina)

    Science.gov (United States)

    Comeau, S.; Gorsky, G.; Jeffree, R.; Teyssié, J.-L.; Gattuso, J.-P.

    2009-09-01

    Thecosome pteropods (shelled pelagic molluscs) can play an important role in the food web of various ecosystems and play a key role in the cycling of carbon and carbonate. Since they harbor an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The impact of changes in the carbonate chemistry was investigated on Limacina helicina, a key species of Arctic ecosystems. Pteropods were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.

  14. Distribution of dissolved inorganic and organic carbon in the Eurasian Basin of the Arctic Ocean

    Science.gov (United States)

    Anderson, Leif G.; Olsson, Kristina; Skoog, Annelie

    Measurements of total carbonate (total inorganic carbon) and total organic carbon were carried out during the International Arctic Ocean Expedition 91 on three sections across the Nansen and Amundsen basins, and into the Makarov Basin. In the surface mixed layer a distinct front was observed to the north, identified by elevated total carbonate concentrations, reflecting the signature of Siberian river runoff. This front forms the southern border of the Siberian Branch of the Transpolar Drift, which is located over the northern part of the Nansen Basin, at the eastern part of the investigated area (about 30° E). To the west, the front is located over the tip of the Yermak Plateau, showing the very wide extent of the Transpolar Drift just north of the Fram Strait. Within the Siberian Branch, about 200 km north of the front, a maximum in the total organic carbon concentration may indicate a shorter residence time since the water left the river mouth, possibly related to a higher flow rate. At the tip of the Morris Jesup Plateau, clear signs of outflowing Canadian Basin waters are seen. In the surface layer, high total carbonate concentrations were present in the water of salinity 33.1, indicating upper halocline water. At intermediate depths (1500 - 2000 m), elevated total carbonate concentrations demonstrate the existence of the outflowing Canadian Basin intermediate water. Part of this outflowing water follows the continental slope to the south while part is injected into the Makarov Basin.

  15. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait.

    Directory of Open Access Journals (Sweden)

    Cecile Cathalot

    Full Text Available The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents. Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m, a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1 compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1. The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger

  16. Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992-2009; sources and atmospheric flux

    Science.gov (United States)

    Lorenson, Thomas D.; Greinert, Jens; Coffin, Richard B.

    2016-01-01

    Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of the Arctic Ocean during eleven surveys spanning the years of 1992-1995 and 2009. During ice-free periods, methane flux from the Beaufort shelf varies from 0.14 to 0.43 mg CH4 m-2 day-1. Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m-2 day-1. Seasonal buildup of methane under ice can produce short-term fluxes of methane from the Beaufort shelf that varies from 0.28 to 1.01 to mg CH4 m-2 day-1. Scaled-up estimates of minimum methane flux from the Beaufort Sea and pan-Arctic shelf for both ice-free and ice-covered periods range from 0.02 Tg CH4 yr-1 and 0.30 Tg CH4 yr-1 respectively to maximum fluxes of 0.18 Tg CH4 yr-1 and 2.2 Tg CH4 yr-1 respectively. A methane flux of 0.36 Tg CH4 yr-1from the deep Arctic Ocean was estimated using data from 1993-94. The flux can be as much as 2.35 Tg CH4 yr-1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ~560 Tg CH4 yr-1. There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.

  17. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait).

    Science.gov (United States)

    Cathalot, Cecile; Rabouille, Christophe; Sauter, Eberhard; Schewe, Ingo; Soltwedel, Thomas

    2015-01-01

    The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents). Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m), a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1) compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1). The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger export of more

  18. The impact of a seasonally ice free Arctic Ocean on the temperature, precipitation and surface mass balance of Svalbard

    Directory of Open Access Journals (Sweden)

    J. J. Day

    2012-01-01

    Full Text Available The observed decline in summer sea ice extent since the 1970s is predicted to continue until the Arctic Ocean is seasonally ice free during the 21st Century. This will lead to a much perturbed Arctic climate with large changes in ocean surface energy flux. Svalbard, located on the present day sea ice edge, contains many low lying ice caps and glaciers and is expected to experience rapid warming over the 21st Century. The total sea level rise if all the land ice on Svalbard were to melt completely is 0.02 m.

    The purpose of this study is to quantify the impact of climate change on Svalbard's surface mass balance (SMB and to determine, in particular, what proportion of the projected changes in precipitation and SMB are a result of changes to the Arctic sea ice cover. To investigate this a regional climate model was forced with monthly mean climatologies of sea surface temperature (SST and sea ice concentration for the periods 1961–1990 and 2061–2090 under two emission scenarios. In a novel forcing experiment, 20th Century SSTs and 21st Century sea ice were used to force one simulation to investigate the role of sea ice forcing. This experiment results in a 3.5 m water equivalent increase in Svalbard's SMB compared to the present day. This is because over 50 % of the projected increase in winter precipitation over Svalbard under the A1B emissions scenario is due to an increase in lower atmosphere moisture content associated with evaporation from the ice free ocean. These results indicate that increases in precipitation due to sea ice decline may act to moderate mass loss from Svalbard's glaciers due to future Arctic warming.

  19. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.

    Science.gov (United States)

    Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

    2014-07-13

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate.

  20. Late Quaternary environments on the western Lomonosov Ridge (Arctic Ocean) - first results from RV Polarstern expedition PS87 (2014)

    Science.gov (United States)

    Spielhagen, Robert F.; Stein, Rüdiger; Mackensen, Andreas; PS87 Shipboard Scientific Party

    2016-04-01

    The interior Arctic Ocean is still one of the least known parts of the earth's surface. In particular this holds true for the deep-sea area north of Greenland which has been reached by research ships only within the last decade. The region is of special interest for climate researchers because numerical climate models predict that under future global warming the shrinking summer sea ice cover will finde a place of refuge here until it totally disappears. In summer 2014 several short and long undisturbed large-volume sediment cores were obtained from the western Lomonosov Ridge between 86.5°N and the North Pole. Here we present first results from site PS87/030 situated at 88°40'N. The combined sedimentary record of a box core and a kasten core analyzed so far is interpreted to represent the environmental variability in the last ca. 200,000 years and can be correlated to comparable records from the eastern Lomonosov Ridge and the Morris Jesup Rise. The well-defined coarse layers with abundant ice-rafted detritus reflect the history of circum-Arctic ice sheets. Planktic foraminifers with a distinct dominance of the polar species were found in most of the analyzed samples and allow to reconstruct the water mass history for this part of the Arctic Ocean. Planktic oxygen and carbon isotope records allow to identify several freshwater events which can be correlated to the decay of ice sheets surrounding the Arctic Ocean. The results presented are, however, preliminary and will be refined by future work including an improved temporal resolution of the records and the addition of further proxy records.

  1. Circumpolar measurements of speciated mercury, ozone and carbon monoxide in the boundary layer of the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. Sommar

    2009-10-01

    Full Text Available Using the Swedish icebreaker Oden as a platform, continuous measurements of airborne mercury (gaseous elemental mercury (Hg0, divalent mercury HgII(g (acronym RGM and mercury attached to particles (PHg and some long-lived trace gases (carbon monoxide CO and ozone O3 were performed over the North Atlantic and the Arctic Ocean. The measurements were performed for nearly three months (July–September, 2005 during the Beringia 2005 expedition (from Göteborg, Sweden via the proper Northwest Passage to the Beringia region Alaska – Chukchi Penninsula – Wrangel Island and in-turn via a north-polar transect to Longyearbyen, Spitsbergen. The Beringia 2005 expedition was the first time that these species have been measured during summer over the Arctic Ocean going from 60° to 90° N.

    During the North Atlantic transect, concentration levels of Hg0, CO and O3 were measured comparable to typical levels for the ambient mid-hemispheric average. However, a rapid increase of Hg0 in air and surface water was observed when entering the ice-covered waters of the Canadian Arctic archipelago. Large parts of the measured waters were supersaturated with respect to Hg0, reflecting a strong disequilibrium. Heading through the sea ice of the Arctic Ocean, a fraction of the strong Hg0} pulse in the water was spilled with some time-delay into the air samples collected ~20 m a.s.l. Several episodes o