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Sample records for amundsen sea embayment

  1. An oceanic heat transport pathway to the Amundsen Sea Embayment

    Science.gov (United States)

    Rodriguez, Angelica R.; Mazloff, Matthew R.; Gille, Sarah T.

    2016-05-01

    The Amundsen Sea Embayment (ASE) on the West Antarctic coastline has been identified as a region of accelerated glacial melting. A Southern Ocean State Estimate (SOSE) is analyzed over the 2005-2010 time period in the Amundsen Sea region. The SOSE oceanic heat budget reveals that the contribution of parameterized small-scale mixing to the heat content of the ASE waters is small compared to advection and local air-sea heat flux, both of which contribute significantly to the heat content of the ASE waters. Above the permanent pycnocline, the local air-sea flux dominates the heat budget and is controlled by seasonal changes in sea ice coverage. Overall, between 2005 and 2010, the model shows a net heating in the surface above the pycnocline within the ASE. Sea water below the permanent pycnocline is isolated from the influence of air-sea heat fluxes, and thus, the divergence of heat advection is the major contributor to increased oceanic heat content of these waters. Oceanic transport of mass and heat into the ASE is dominated by the cross-shelf input and is primarily geostrophic below the permanent pycnocline. Diagnosis of the time-mean SOSE vorticity budget along the continental shelf slope indicates that the cross-shelf transport is sustained by vorticity input from the localized wind-stress curl over the shelf break.

  2. Modern foraminifera assemblages in the Amundsen Sea Embayment

    Science.gov (United States)

    Ewa Jernas, Patrycja; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Lander Rasmussen, Tine; Forwick, Matthias; Mackensen, Andreas; Schröder, Michael; Smith, James; Klages, Johann Philipp

    2015-04-01

    The West Antarctic Ice Sheet (WAIS) is considered the most unstable part of the Antarctic Ice Sheet. As the WAIS is mostly grounded below sea level, its stability is of great concern. A collapse of large parts of the WAIS would result in a significant global sea-level rise. At present, the WAIS shows dramatic ice loss in its Amundsen Sea sector, especially in Pine Island Bay. Pine Island Glacier (PIG) is characterised by fast flow, major thinning and rapid grounding-line retreat. Its mass los over recent decades is generally attributed to melting caused by the inflow of warm Circumpolar Deep Water (CDW). Future melting of PIG may result in a sea level tipping point, because it could trigger widespread collapse of the WAIS, especially when considering ongoing climate change. Our research project aims to establish proxies (integration of foraminifera, sediment properties and oceanographic data) for modern environmental conditions by analysing seafloor surface sediments along a transect from the glacier proximal settings to the middle-outer shelf in the eastern Amundsen Sea Embayment. These proxies will then be applied on sediment records spanning the Holocene back to the Last Glacial Maximum for reconstructing spatial and temporal variations of CDW upwelling and ice-ocean interactions during the past c. 23,000 years. We will present preliminary results from the analyses of ten short marine sediment cores (multi and box cores) collected during expeditions JR179 (2008) and ANT-XXVI/3 (2010) along a transect from inner Pine Island Bay to the middle-outer shelf part of the Abbot Palaeo-Ice Stream Trough at water depths ranging from 458 m (middle shelf) to 1444 m (inner shelf). The sediment cores are currently investigated for distribution patterns of planktonic and benthic foraminifera and grain-size distribution at 1 cm resolution. Core tops (0-10 cm) were stained with Rose Bengal for living benthic foraminifera investigations. The chronology of the cores will be based

  3. Improving Constraints on Paleo Ice Sheets in the Amundsen Sea Embayment

    Science.gov (United States)

    Larter, Robert D.; Gohl, Karsten; Bentley, Michael J.

    2010-01-01

    Amundsen Sea Embayment: Tectonic and Climatic Evolution; Granada, Spain, 9 September 2009; Geoscientists working on the Amundsen Sea Embayment (ASE) of West Antarctica met at a workshop during the First Antarctic Climate Evolution Symposium to discuss recent advances from, and future priorities for, work in this region. The ASE is the most rapidly changing sector of the West Antarctic Ice Sheet (WAIS) and contains enough ice to raise sea level by 1.2 meters. Ice sheet modeling studies suggest that this sector of the WAIS is potentially unstable. Considerable efforts have been made through several national Antarctic programs to acquire new data on the geological structure, subglacial topography, bathymetry, and glacial history of this remote region. These data are important for establishing boundary conditions for ice sheet modeling, for providing constraints on past ice sheet changes that can be used to test models, and for putting recent changes into a longer-term context.

  4. Sea level contribution from Amundsen Embayment in the last 200 years

    Science.gov (United States)

    Barletta, Valentina R.; Rovira-Navarro, Marc; Bordoni, Andrea; Bevis, Michael; Wilson, Terry; Willis, Michael J.

    2017-04-01

    The Amundsen Embayment presents an interesting combination of ice mass changes, solid Earth properties and geodetic observations that allows us to infer and constrain the cumulative ice mass lost from this region since the end of Little Ice Age (LIA). The rate of present day mass changes in this region is about 130 Gt/yr, which is about half of the total ice loss rate for the whole of Greenland, making the Amundsen Sea Embayment the location of one of the fastest ice losses in the world. A very soft mantle beneath Amundsen sector makes the solid Earth rebound response to present-day and recent ice melting very rapid, and on very short time scale, with a sustained bedrock uplift rate that is clearly observed by the Antarctic GPS Network (ANET). We built a suitable Earth model and a very large ensemble of possible ice history for the past 200 years based on the pattern of present day ice changes. We simulate the rebound produced by our Earth model for each element of the ice history ensemble and we find that only a relatively small subset can skillfully reproduce the observations. All the ice histories in this subset have very similar cumulative ice loss since end of LIA. In terms of sea level rise equivalent the best models produce around 15 mm, which is between 8% and 10% of the global sea level raise over the same period. Another relevant finding is that almost all good models show a sudden increase in the mass loss in the recent past. We further show with a sensitivity study that with our ensemble of models we already explore most of the meaningful possible scenarios. However we investigate further the effect of localized variations in the geometry of the ice changes, such as the strong retreat of grounding line in Pine Island and Thwaites glaciers.

  5. Evaluation of four global reanalysis products using in situ observations in the Amundsen Sea Embayment, Antarctica

    Science.gov (United States)

    Jones, R. W.; Renfrew, I. A.; Orr, A.; Webber, B. G. M.; Holland, D. M.; Lazzara, M. A.

    2016-06-01

    The glaciers within the Amundsen Sea Embayment (ASE), West Antarctica, are amongst the most rapidly retreating in Antarctica. Meteorological reanalysis products are widely used to help understand and simulate the processes causing this retreat. Here we provide an evaluation against observations of four of the latest global reanalysis products within the ASE region—the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), Japanese 55-year Reanalysis (JRA-55), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective-Analysis for Research and Applications (MERRA). The observations comprise data from four automatic weather stations (AWSs), three research vessel cruises, and a new set of 38 radiosondes all within the period 2009-2014. All four reanalyses produce 2 m temperature fields that are colder than AWS observations, with the biases varying from approximately -1.8°C (ERA-I) to -6.8°C (MERRA). Over the Amundsen Sea, spatially averaged summertime biases are between -0.4°C (JRA-55) and -2.1°C (MERRA) with notably larger cold biases close to the continent (up to -6°C) in all reanalyses. All four reanalyses underestimate near-surface wind speed at high wind speeds (>15 m s-1) and exhibit dry biases and relatively large root-mean-square errors (RMSE) in specific humidity. A comparison to the radiosonde soundings shows that the cold, dry bias at the surface extends into the lower troposphere; here ERA-I and CFSR reanalyses provide the most accurate profiles. The reanalyses generally contain larger temperature and humidity biases, (and RMSE) when a temperature inversion is observed, and contain larger wind speed biases (~2 to 3 m s-1), when a low-level jet is observed.

  6. First exposure ages from the Amundsen Sea Embayment, West Antarctica: The Late Quaternary context for recent thinning of Pine Island, Smith, and Pope Glaciers

    Science.gov (United States)

    Johnson, Joanne S.; Bentley, Michael J.; Gohl, Karsten

    2008-03-01

    Dramatic changes (acceleration, thinning, and grounding-lineretreat of major ice streams) in the Amundsen Sea sector ofthe West Antarctic Ice Sheet (WAIS) have been observed duringthe past two decades, but the millennial-scale context for thesechanges is not yet known. We present the first surface exposureages recording thinning of Pine Island, Smith, and Pope Glaciers,which all drain into the Amundsen Sea. From these we infer progressivethinning of Pine Island Glacier at an average rate of 3.8 ±0.3 cm yr-1 for at least the past 4.7 k.y., and of Smithand Pope Glaciers at 2.3 ± 0.2 cm yr-1 over thepast 14.5 k.y. These rates are more than an order of magnitudelower than the 1.6 m yr-1 recorded by satellite altimetryfor Pine Island Glacier in the period 1992-1996. Similarlylow long-term rates (2.5-9 cm yr-1 since 10 ka)have been reported farther west in the Ford Ranges, Marie ByrdLand, but in that area, the same rates of thinning continueto the present day. Our data provide the first evidence thatputs into context recent rates of thinning of the WAIS in theAmundsen Sea Embayment and demonstrates that these are unusuallyrapid. The data also provide much-needed constraints for icesheet models, which are the primary tool for predicting thefuture behavior of the WAIS and its likely contribution to sea-levelrise.

  7. Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period.

    Science.gov (United States)

    Klages, Johann P; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Smith, James A; Graham, Alastair G C; Nitsche, Frank O; Frederichs, Thomas; Jernas, Patrycja E; Gohl, Karsten; Wacker, Lukas

    2017-01-01

    Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5-19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2-3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period.

  8. Understanding the Amundsen Sea Low

    Science.gov (United States)

    McDonald, Adrian

    2016-04-01

    The Amundsen Sea Low (ASL) is a climatological low pressure system located between 170-300 ° E and 60-75°S and is a key component of the non-zonal climatological circulation at high southern latitudes. With reanalysis output identifying that climatologically the low in the Amundsen Sea is the deepest of three mean sea level pressure (MSLP) centres observed around Antarctica. The ASL strongly modulates West Antarctic climate with impacts on sea ice extent, temperature and precipitation, via its controlling influence on the variability of the meridional wind field. It has also been shown to have a significant influence on the atmospheric circulation in the Ross Sea region and to strongly modulate temperature and moisture advection over the Antarctic Peninsula. Previous work has demonstrated strong relationships between the depth of the ASL and cyclone densities in the region. However, interestingly a recent review identified that it is not easy to relate the storm density and depths of the cyclones to the climatological ASL, since the climatological location of the ASL does not occur at a clear maximum of storm activity. This study examines output from the ERA-interim reanalyses around Antarctica to further understand the contributors to the climatological pattern, partially in an effort to identify whether a more physically meaningful ASL depth index (normally simply defined as the monthly minimum MSLP) can be created. In this effort, storm track data derived from the ERA-Interim reanalysis and mean sea level pressure data bandpass filtered to accentuate synoptic scale variability are first examined. The contribution of persistent positive anomalies in the mean sea level pressure (defined as 8hPa positive anomalies from the climatological mean for a period of 5 days) in the region surrounding the Amundsen sea is also examined to identify whether blocking plays a role. Finally, the frequency of persistent negative anomalies (defined as a negative 8hPa occurring for

  9. Gravitational signature and apparent mass changes in Amundsen Embayment caused by low viscosity GIA model constrained by rapid bedrock displacement

    Science.gov (United States)

    Barletta, V. R.; Bevis, M.; Smith, B. E.; Wilson, T. J.; Willis, M. J.; Brown, A.; Bordoni, A.; Khan, S. A.; Smalley, R., Jr.; Kendrick, E. C.; Konfal, S. A.; Caccamise, D.; Aster, R.; Chaput, J. A.; Heeszel, D.; Wiens, D.; Lloyd, A. J.

    2015-12-01

    The Amundsen Embayment sector of West Antarctica is experiencing some of the fastest sustained bedrock uplift rates in the world. These motions, recorded by the Antarctic GPS Network (ANET), cannot be explained in terms of the earth's elastic response to contemporary ice loss, and the residues are far too rapid to be explained using traditional GIA models. We use 13 years of very high resolution DEM-derived ice mass change fields over the Amundsen sector to compute the elastic signal and remove it from the observed geodetic time series. We obtain a very large residual - up to 5 times larger than the computed elastic response. Low or very low mantle viscosities are expected in this area based on existing heat flow estimates, seismic velocity anomalies, thin crust, and active volcanism, all of which are associated with geologically recent rifting. We hypothesize that the rapid crustal displacement manifests a low viscosity short-time-scale response to post- Little Ice Age ice mass changes, including ice losses developed in the last decade or so. A plausible ice history for the last hundred years is made by using the actual measurements from 2002 to 2014, and 25% of the present day melting rate before 2002. We then simulate and fit the bedrock displacement - both vertical and horizontal - with a spherical compressible viscoelastic Earth model having a low viscosity shallow upper mantle. We show that we can constrain the shallow upper mantle viscosity very well and also explain most of the signal (amplitude and direction) by using 2 x10^18 Pa s. However we are not able to precisely constrain the thickness of the lithosphere (the preferred thickness is more than 50 km, quite thick for that region) or ice history. By using our preferred set up (earth model + ice history) we compute the GIA gravitational signature and convert it in equivalent superficial water density (see figure) that can be directly used to correct the mass changes observed by GRACE.For the Amundsen

  10. Identifying glacial meltwater in the Amundsen Sea, Antarctica

    Science.gov (United States)

    Biddle, Louise; Heywood, Karen; Jenkins, Adrian; Kaiser, Jan

    2016-04-01

    Pine Island Glacier, located in the Amundsen Sea, is losing mass rapidly due to relatively warm ocean waters melting its ice shelf from below. The resulting increase in meltwater production may be the root of the freshening in the Ross Sea over the last 30 years. Tracing the meltwater travelling away from the ice sheets is important in order to identify the regions most affected by the increased input of this water type. We use water mass characteristics (temperature, salinity, O2 concentration) derived from 105 CTD casts during the Ocean2ice cruise on RRS James Clark Ross in January-March 2014 to calculate meltwater fractions north of Pine Island Glacier. The data show maximum meltwater fractions at the ice front of up to 2.4 % and a plume of meltwater travelling away from the ice front along the 1027.7 kg m-3 isopycnal. We investigate the reliability of these results and attach uncertainties to the measurements made to ascertain the most reliable method of meltwater calculation in the Amundsen Sea. Processes such as atmospheric interaction and biological activity also affect the calculated apparent meltwater fractions. We analyse their effects on the reliability of the calculated meltwater fractions across the region using a bulk mixed layer model based on the one-dimensional Price-Weller-Pinkel model (1986). The model includes sea ice, dissolved oxygen concentrations and a simple respiration model, forced by NCEP climatology and an initial linear mixing profile between Winter Water (WW) and Circumpolar Deep Water (CDW). The model mimics the seasonal cycle of mixed layer warming and freshening and simulates how increases in sea ice formation and the influx of slightly cooler Lower CDW impact on the apparent meltwater fractions. These processes could result in biased meltwater signatures across the eastern Amundsen Sea.

  11. Microzooplankton herbivory and community structure in the Amundsen Sea, Antarctica

    Science.gov (United States)

    Yang, Eun Jin; Jiang, Yong; Lee, SangHoon

    2016-01-01

    We examined microzooplankton abundance, community structure, and grazing impact on phytoplankton in the Amundsen Sea, Western Antarctica, during the early austral summer from December 2010 to January 2011. Our study area was divided into three regions based on topography, hydrographic properties, and trophic conditions: (1) the Oceanic Zone (OZ), with free sea ice and low phytoplankton biomass dominated by diatoms; (2) the Sea Ice Zone (SIZ), covered by heavy sea ice with colder water, lower salinity, and dominated by diatoms; and (3) the Amundsen Sea Polynya (ASP), with high phytoplankton biomass dominated by Phaeocystis antarctica. Microzooplankton biomass and communities associated with phytoplankton biomass and composition varied among regions. Heterotrophic dinoflagellates (HDF) were the most significant grazers in the ASP and OZ, whereas ciliates co-dominated with HDF in the SIZ. Microzooplankton grazing impact is significant in our study area, particularly in the ASP, and consumed 55.4-107.6% of phytoplankton production (average 77.3%), with grazing impact increasing with prey and grazer biomass. This result implies that a significant proportion of the phytoplankton production is not removed by sinking or other grazers but grazed by microzooplankton. Compared with diatom-based systems, Phaeocystis-based production would be largely remineralized and/or channeled through the microbial food web through microzooplankton grazing. In these waters the major herbivorous fate of phytoplankton is likely mediated by the microzooplankton population. Our study confirms the importance of herbivorous protists in the planktonic ecosystems of high latitudes. In conclusion, microzooplankton herbivory may be a driving force controlling phytoplankton growth in early summer in the Amundsen Sea, particularly in the ASP.

  12. Abbot Ice Shelf, structure of the Amundsen Sea continental margin and the southern boundary of the Bellingshausen Plate seaward of West Antarctica.

    Science.gov (United States)

    Cochran, James R; Tinto, Kirsty J; Bell, Robin E

    2015-05-01

    Inversion of NASA Operation IceBridge airborne gravity over the Abbot Ice Shelf in West Antarctica for subice bathymetry defines an extensional terrain made up of east-west trending rift basins formed during the early stages of Antarctica/Zealandia rifting. Extension is minor, as rifting jumped north of Thurston Island early in the rifting process. The Amundsen Sea Embayment continental shelf west of the rifted terrain is underlain by a deeper, more extensive sedimentary basin also formed during rifting between Antarctica and Zealandia. A well-defined boundary zone separates the mildly extended Abbot extensional terrain from the deeper Amundsen Embayment shelf basin. The shelf basin has an extension factor, β, of 1.5-1.7 with 80-100 km of extension occurring across an area now 250 km wide. Following this extension, rifting centered north of the present shelf edge and proceeded to continental rupture. Since then, the Amundsen Embayment continental shelf appears to have been tectonically quiescent and shaped by subsidence, sedimentation, and the advance and retreat of the West Antarctic Ice Sheet. The Bellingshausen Plate was located seaward of the Amundsen Sea margin prior to incorporation into the Antarctic Plate at about 62 Ma. During the latter part of its independent existence, Bellingshausen plate motion had a clockwise rotational component relative to Antarctica producing convergence across the north-south trending Bellingshausen Gravity Anomaly structure at 94°W and compressive deformation on the continental slope between 94°W and 102°W. Farther west, the relative motion was extensional along an east-west trending zone occupied by the Marie Byrd Seamounts. Abbot Ice Shelf is underlain by E-W rift basins created at ∼90 Ma Amundsen shelf shaped by subsidence, sedimentation, and passage of the ice sheet Bellingshausen plate boundary is located near the base of continental slope and rise.

  13. Seasonal sea ice changes in the Amundsen Sea, Antarctica, over the period of 1979–2014

    Directory of Open Access Journals (Sweden)

    S. E. Stammerjohn

    2015-06-01

    Full Text Available Abstract Recent attention has focused on accelerated glacial losses along the Amundsen Sea coast that result from changes in atmosphere and ocean circulation, with sea ice playing a mediating but not well-understood role. Here, we investigated how sea ice has changed in the Amundsen Sea over the period of 1979 to 2014, focusing on spatio-temporal changes in ice edge advance/retreat and percent sea ice cover in relation to changes in winds. In contrast to the widespread sea ice decreases to the east and increases to the west of the Amundsen Sea, sea ice changes in the Amundsen Sea were confined to three areas: (i offshore of the shelf break, (ii the southern Pine Island Polynya, and (iii the eastern Amundsen Sea Polynya. Offshore, a 2-month decrease in ice season duration coincided with seasonal shifts in wind speed and direction from March to May (relating to later ice advance and from September to August (relating to earlier retreat, consistent with reported changes in the depth/location of the Amundsen Sea Low. In contrast, sea ice decreases in the polynya areas corresponded to episodic or step changes in spring ice retreat (earlier by 1–2 months and were coincident with changes to Thwaites Iceberg Tongue (located between the two polynyas and increased southeasterly winds. Temporal correlations among these three areas were weak, indicating different local forcing and/or differential response to large-scale forcing. Although our analysis has shown that part of the variability can be explained by changes in winds or to the coastal icescape, an additional but unknown factor is how sea ice has responded to changes in ocean heat and freshwater inputs. Unraveling cause and effect, critical for predicting changes to this rapidly evolving ocean-ice shelf-sea ice system, will require in situ observations, along with improved remote sensing capabilities and ocean modeling.

  14. Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean) : Iron biogeochemistry

    NARCIS (Netherlands)

    Gerringa, Loes J. A.; Alderkamp, Anne-Carlijn; Laan, Patrick; Thuroczy, Charles-Edouard; De Baar, Hein J. W.; Mills, Matthew M.; van Dijken, Gert L.; van Haren, Hans; Arrigo, Kevin R.

    2012-01-01

    Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive cont

  15. Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean) : Iron biogeochemistry

    NARCIS (Netherlands)

    Gerringa, Loes J. A.; Alderkamp, Anne-Carlijn; Laan, Patrick; Thuroczy, Charles-Edouard; De Baar, Hein J. W.; Mills, Matthew M.; van Dijken, Gert L.; van Haren, Hans; Arrigo, Kevin R.

    2012-01-01

    Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive

  16. Multichannel Seismic Reflection Data - SCAR - Amundsen Sea - 1986-1987, SDLS CD-ROM vol 23

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1986-87 in the Amundsen Sea, Antarctica, by the Japan National Oil Corporation....

  17. Sea ice algal biomass and physiology in the Amundsen Sea, Antarctica

    Directory of Open Access Journals (Sweden)

    Kevin R. Arrigo

    2014-07-01

    Full Text Available Abstract Sea ice covers approximately 5% of the ocean surface and is one of the most extensive ecosystems on the planet. The microbial communities that live in sea ice represent an important food source for numerous organisms at a time of year when phytoplankton in the water column are scarce. Here we describe the distributions and physiology of sea ice microalgae in the poorly studied Amundsen Sea sector of the Southern Ocean. Microalgal biomass was relatively high in sea ice in the Amundsen Sea, due primarily to well developed surface communities that would have been replenished with nutrients during seawater flooding of the surface as a result of heavy snow accumulation. Elevated biomass was also occasionally observed in slush, interior, and bottom ice microhabitats throughout the region. Sea ice microalgal photophysiology appeared to be controlled by the availability of both light and nutrients. Surface communities used an active xanthophyll cycle and effective pigment sunscreens to protect themselves from harmful ultraviolet and visible radiation. Acclimation to low light microhabitats in sea ice was facilitated by enhanced pigment content per cell, greater photosynthetic accessory pigments, and increased photosynthetic efficiency. Photoacclimation was especially effective in the bottom ice community, where ready access to nutrients would have allowed ice microalgae to synthesize a more efficient photosynthetic apparatus. Surprisingly, the pigment-detected prymnesiophyte Phaeocystis antarctica was an important component of surface communities (slush and surface ponds where its acclimation to high light may precondition it to seed phytoplankton blooms after the sea ice melts in spring.

  18. Comparing ice discharge through West Antarctic Gateways: Weddell vs. Amundsen Sea warming

    Directory of Open Access Journals (Sweden)

    M. A. Martin

    2015-03-01

    Full Text Available Future changes in Antarctic ice discharge will be largely controlled by the fate of the floating ice shelves, which exert a back-stress onto Antarctica's marine outlet glaciers. Ice loss in response to warming of the Amundsen Sea has been observed and investigated as a potential trigger for the marine ice-sheet instability. Recent observations and simulations suggest that the Amundsen Sea Sector might already be unstable which would have strong implications for global sea-level rise. At the same time, regional ocean projections show much stronger warm-water intrusion into ice-shelf cavities in the Weddell Sea compared to the observed Amundsen warming. Here we present results of numerical ice sheet modelling with the Parallel Ice Sheet Model (PISM which show that idealized, step-function type ocean warming in the Weddell Sea leads to more immediate ice discharge with a higher sensitivity to small warming levels than the same warming in the Amundsen Sea. This is consistent with the specific combination of bedrock and ice topography in the Weddell Sea Sector which results in an ice sheet close to floatation. In response to even slight ocean warming, ice loss increases rapidly, peaks and declines within one century. While the cumulative ice loss in the Amundsen Sea Sector is of similar magnitude after five centuries of continued warming, ice loss increases at a slower pace and only for significantly higher warming levels. Although there is more marine ice stored above sea level in close vicinity of the grounding line compared to the Weddell Sea Sector, the ice sheet is farther from floatation and the grounding line initially retreats more slowly.

  19. On the difficulty of modeling Circumpolar Deep Water intrusions onto the Amundsen Sea continental shelf

    Science.gov (United States)

    Nakayama, Y.; Timmermann, R.; Schröder, M.; Hellmer, H. H.

    2014-12-01

    In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet, resulting in high basal melt rates. However, none of the high resolution global models resolving all the small ice shelves around Antarctica can reproduce a realistic CDW flow onto the Amundsen Sea continental shelf, and previous studies show simulated bottom potential temperature at the Pine Island Ice Shelf front of about -1.8 °C. In this study, using the Finite-Element Sea ice-ice shelf-Ocean Model (FESOM), we reproduce warm CDW intrusions onto the Amundsen Sea continental shelf and realistic melt rates of the ice shelves in West Antarctica. To investigate the importance of horizontal resolution, forcing, horizontal diffusivity, and the effect of grounded icebergs, eight sensitivity experiments are conducted. To simulate the CDW intrusion realistically, a horizontal resolution of about 5 km or smaller is required. The choice of forcing is also important and the cold bias in the NCEP/NCAR reanalysis over the eastern Amundsen Sea prevents warm CDW from intruding onto the continental shelf. On the other hand, the CDW intrusion is not highly sensitive to the strength of horizontal diffusion. The effect of grounded icebergs located off Bear Peninsula is minor, but may act as a buffer to an anomalously cold year.

  20. Sinking Particle Flux in the Sea Ice Zone of the Amundsen Shelf, Antarctica

    Science.gov (United States)

    Kim, M.; Hwang, J.; Kim, H. J.; Kim, D.; Ducklow, H. W.; Lee, S. H.; Yang, E. J.; Lee, S.

    2014-12-01

    We have examined the flux, compositions of biogenic components, and isotopic values of sinking particles collected by a sediment trap deployed in the sea ice zone (SIZ) of the Amundsen Sea from January 2011 for one year. Major portion of the particle flux occurred during the austral summer in January and February when sea ice concentration was reduced to below 60 %. Biogenic components, dominated by opal, accounted for over 75 % during this high flux period. The dominant source of sinking particles shifted from diatoms to soft-tissued organisms, evidenced by high particulate organic carbon (POC) content (> 30 %) during the polar night. CaCO3 content and its contribution to total particle flux were low throughout the study period. Contribution of aged POC likely supplied from sediment resuspension was considerable only from October to December, evidenced by low radiocarbon content and relatively high (30-50 %) content of the non-biogenic component. When compared to POC flux inside the Amundsen Sea polynya obtained by the US Amundsen Sea Polynya International Research Expedition (ASPIRE), the POC flux integrated over the austral summer in the SIZ was virtually identical although maximum POC flux was about half that inside the Amundsen Sea polynya. This comparatively high POC flux in the SIZ may be caused by persistence of phytoplankton bloom for longer period and more efficient export of organic matter owing to the diatom-dominant plankton community. If this observation is a general phenomenon on the Amundsen shelf, the role of the SIZ compared to the polynyas need to be examined more carefully when trying to characterize the POC export in this region.

  1. Spatial and temporal variability of sea ice in the southern Beaufort Sea and Amundsen Gulf: 1980-2004

    Science.gov (United States)

    Galley, R. J.; Key, E.; Barber, D. G.; Hwang, B. J.; Ehn, J. K.

    2008-05-01

    Changing extent, location, and motion of the Arctic perennial pack affect the annual evolution of seasonal ice zones. Canadian Ice Service digital ice charts covering the southern Beaufort Sea and Amundsen Gulf are used to illustrate summer and winter conditions and trends between 1980 and 2004 for several sea ice stages of development. Results illustrate average sea ice conditions within the region in summer and winter for predominant sea ice types and changes in the relative concentration of sea ice types in summer and winter. In summer, a trend toward increased old sea ice concentration occurred near the mouth of Amundsen Gulf, with a trend toward decreasing summer first-year sea ice farther west. In winter, increasing thick first-year sea ice extent appears to be replacing young sea ice within the flaw lead system in the region. The dynamically driven breakup of sea ice in spring in the Amundsen Gulf is a highly variable event taking anywhere between 2 and 22 weeks to completely remove ice from the gulf. The timing and duration of the open water season depends upon the extent and timing of old ice influx. Freezeup occurs very quickly, proceeding from west to east with little temporal variability. The results of this paper are used to set the context for the Canadian Arctic Shelf Exchange Study (CASES) in terms of sea ice dynamic and thermodynamic processes.

  2. Temperature, salinity and oxygen data collected from the Oden in the Amundsen and Ross Seas, 2010 - 2011 (NODC Accession 0104260)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data were collected to investigate the physical oceanography of the Amundsen and Ross Seas. Funded under the following projects: Physical Oceanography of the...

  3. Antarctic sea ice increase consistent with intrinsic variability of the Amundsen Sea Low

    Science.gov (United States)

    Turner, John; Hosking, J. Scott; Marshall, Gareth J.; Phillips, Tony; Bracegirdle, Thomas J.

    2016-04-01

    We investigate the relationship between atmospheric circulation variability and the recent trends in Antarctic sea ice extent (SIE) using Coupled Model Intercomparison Project Phase 5 (CMIP5) atmospheric data, ECMWF Interim reanalysis fields and passive microwave satellite data processed with the Bootstrap version 2 algorithm. Over 1979-2013 the annual mean total Antarctic SIE increased at a rate of 195 × 103 km2 dec-1 (1.6 % dec-1), p 4.0 % dec-1) has been in the Ross Sea sector. Off West Antarctica there is a high correlation between trends in SIE and trends in the near-surface winds. The Ross Sea SIE seasonal trends are positive throughout the year, but largest in spring. The stronger meridional flow over the Ross Sea has been driven by a deepening of the Amundsen Sea Low (ASL). Pre-industrial control and historical simulations from CMIP5 indicate that the observed deepening of the ASL and stronger southerly flow over the Ross Sea are within the bounds of modeled intrinsic variability. The spring trend would need to continue for another 11 years for it to fall outside the 2 standard deviation range seen in 90 % of the simulations.

  4. In situ phytoplankton distributions in the Amundsen Sea Polynya measured by autonomous gliders

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    Oscar Schofield

    2015-10-01

    Full Text Available Abstract The Amundsen Sea Polynya is characterized by large phytoplankton blooms, which makes this region disproportionately important relative to its size for the biogeochemistry of the Southern Ocean. In situ data on phytoplankton are limited, which is problematic given recent reports of sustained change in the Amundsen Sea. During two field expeditions to the Amundsen Sea during austral summer 2010–2011 and 2014, we collected physical and bio-optical data from ships and autonomous underwater gliders. Gliders documented large phytoplankton blooms associated with Antarctic Surface Waters with low salinity surface water and shallow upper mixed layers (< 50 m. High biomass was not always associated with a specific water mass, suggesting the importance of upper mixed depth and light in influencing phytoplankton biomass. Spectral optical backscatter and ship pigment data suggested that the composition of phytoplankton was spatially heterogeneous, with the large blooms dominated by Phaeocystis and non-bloom waters dominated by diatoms. Phytoplankton growth rates estimated from field data (≤ 0.10 day−1 were at the lower end of the range measured during ship-based incubations, reflecting both in situ nutrient and light limitations. In the bloom waters, phytoplankton biomass was high throughout the 50-m thick upper mixed layer. Those biomass levels, along with the presence of colored dissolved organic matter and detritus, resulted in a euphotic zone that was often < 10 m deep. The net result was that the majority of phytoplankton were light-limited, suggesting that mixing rates within the upper mixed layer were critical to determining the overall productivity; however, regional productivity will ultimately be controlled by water column stability and the depth of the upper mixed layer, which may be enhanced with continued ice melt in the Amundsen Sea Polynya.

  5. Ice core reconstruction of sea ice change in the Amundsen-Ross Seas since 1702 A.D.

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    Thomas, Elizabeth R.; Abram, Nerilie J.

    2016-05-01

    Antarctic sea ice has been increasing in recent decades, but with strong regional differences in the expression of sea ice change. Declining sea ice in the Bellingshausen Sea since 1979 (the satellite era) has been linked to the observed warming on the Antarctic Peninsula, while the Ross Sea sector has seen a marked increase in sea ice during this period. Here we present a 308 year record of methansulphonic acid from coastal West Antarctica, representing sea ice conditions in the Amundsen-Ross Sea. We demonstrate that the recent increase in sea ice in this region is part of a longer trend, with an estimated ~1° northward expansion in winter sea ice extent (SIE) during the twentieth century and a total expansion of ~1.3° since 1702. The greatest reconstructed SIE occurred during the mid-1990s, with five of the past 30 years considered exceptional in the context of the past three centuries.

  6. Physical-biological coupling in the Amundsen Sea, Antarctica: Influence of physical factors on phytoplankton community structure and biomass

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    Lee, Youngju; Yang, Eun Jin; Park, Jisoo; Jung, Jinyoung; Kim, Tae Wan; Lee, SangHoon

    2016-11-01

    To understand the spatial distribution of phytoplankton communities in various habitats in the Amundsen Sea, western Antarctica, a field survey was conducted at 15 stations during the austral summer, from December 2013 to January 2014. Water samples were analyzed by microscopy. We found high phytoplankton abundance and biomass in the Amundsen Sea polynya (ASP). Their strong positive correlation with water temperature suggests that phytoplankton biomass accumulated in the surface layer of the stratified polynya. In the ASP, the predominant phytoplankton species was Phaeocystis antarctica, while diatoms formed a major group in the sea ice zone, especially Fragilariopsis spp., Chaetoceros spp., and Proboscia spp. Although this large diatom abundance sharply decreased just off the marginal sea ice zone, weakly silicified diatoms, due to their high buoyancy, were distributed at almost all stations on the continental shelf. Dictyocha speculum appeared to favor the area between the marginal sea ice zone and the ASP in contrast to cryptophytes and picophytoplankton, whose abundance was higher in the area between the continental shelf and the open ocean of Amundsen Sea. Several environmental factors were found to affect the spatial variation of phytoplankton species, but the community structure appeared to be controlled mainly by the seawater density related to sea-ice melting and water circulation in the Amundsen Sea.

  7. Could promontories have restricted sea-glacier penetration into marine embayments during Snowball Earth events?

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    Campbell, Adam J.; Massarano, Betzalel; Waddington, Edwin D.; Warren, Stephen G.

    2017-05-01

    During the Neoproterozoic (˜ 1000-550 Ma), Earth experienced several climate excursions of extreme cold, often referred to as the Snowball Earth events. During these periods, thick flowing ice, referred to as sea glaciers, covered the entire planet's oceans. In addition, there is evidence that photosynthetic eukaryotic algae survived during these periods. With thick sea glaciers covering the oceans, it is uncertain where these organisms survived. One hypothesis is that these algae survived in marine embayments hydrologically connected to the global ocean, where the flow of sea glacier could be resisted. In order for an embayment to act as a refugium, the invading sea glacier must not completely penetrate the embayment. Recent studies have shown that straight-sided marine embayments could have prevented full sea-glacier penetration under a narrow range of climate conditions suitable for the Snowball Earth events. Here we test whether promontories, i.e., headlands emerging from a side shoreline, could further restrict sea-glacier flow. We use an ice-flow model, suitable for floating ice, to determine the flow of an invading sea glacier. We show that promontories can expand the range of climate conditions allowing refugia by resisting the flow of invading sea glaciers.

  8. The influence of light and water mass on bacterial population dynamics in the Amundsen Sea Polynya

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    Inga Richert

    2015-04-01

    Full Text Available Abstract Despite being perpetually cold, seasonally ice-covered and dark, the coastal Southern Ocean is highly productive and harbors a diverse microbiota. During the austral summer, ice-free coastal patches (or polynyas form, exposing pelagic organisms to sunlight, triggering intense phytoplankton blooms. This strong seasonality is likely to influence bacterioplankton community composition (BCC. For the most part, we do not fully understand the environmental drivers controlling high-latitude BCC and the biogeochemical cycles they mediate. In this study, the Amundsen Sea Polynya was used as a model system to investigate important environmental factors that shape the coastal Southern Ocean microbiota. Population dynamics in terms of occurrence and activity of abundant taxa was studied in both environmental samples and microcosm experiments by using 454 pyrosequencing of 16S rRNA genes. We found that the BCC in the photic epipelagic zone had low richness, with dominant bacterial populations being related to taxa known to benefit from high organic carbon and nutrient loads (copiotrophs. In contrast, the BCC in deeper mesopelagic water masses had higher richness, featuring taxa known to benefit from low organic carbon and nutrient loads (oligotrophs. Incubation experiments indicated that direct impacts of light and competition for organic nutrients are two important factors shaping BCC in the Amundsen Sea Polynya.

  9. Glacial retreat in the Amundsen Sea sector, West Antarctica - first cosmogenic evidence from central Pine Island Bay and the Kohler Range

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    Lindow, Julia; Castex, Marion; Wittmann, Hella; Johnson, Joanne S.; Lisker, Frank; Gohl, Karsten; Spiegel, Cornelia

    2014-08-01

    The Amundsen Sea Embayment of West Antarctica hosts one of the most rapidly changing sectors of the West Antarctic Ice Sheet. With the fastest-flowing ice streams in Antarctica, the region around Pine Island Bay is characterized by rapid ice-sheet thinning and grounding-line retreat. Published surface-exposure data are limited to a few isolated nunataks making it difficult to assess the long-term deglacial history of the area. To address this, we correlate existing records of lateral ice-stream retreat from marine sediment cores with onshore glacial thinning in two key areas of eastern Marie Byrd Land: the Kohler Range and Pine Island Bay. Our 10Be surface-exposure ages are the first from the isolated Kohler Range and show that the nunataks there became ice-free between 8.6 and 12.6 ka. This implies a minimum long-term average thinning rate of 3.3 ± 0.3 cm/yr, which is one order of magnitude lower than recent rates based on satellite data. We also present pre- to early Holocene 10Be surface-exposure ages from two islands located approximately 80 km downstream of the Pine Island Glacier ice-shelf front to constrain the lateral deglacial history in the Pine Island Bay area. This study provides insight into the significance of local ice sheet variations and suggests that the post-LGM history in the Amundsen Sea sector was characterized by glacial thinning as well as lateral retreat in pre- to early Holocene times.

  10. Robust response of the Amundsen Sea Low to stratospheric ozone depletion

    Science.gov (United States)

    England, Mark R.; Polvani, Lorenzo M.; Smith, Karen L.; Landrum, Laura; Holland, Marika M.

    2016-08-01

    The effect of stratospheric ozone depletion on the Amundsen Sea Low (ASL), a climatological low-pressure center important for the climate of West Antarctica, remains uncertain. Using state-of-the-art climate models, we here show that stratospheric ozone depletion can cause a statistically significant deepening of the ASL in summer with an amplitude of approximately 1 hPa per decade. We are able to attribute the modeled changes in the ASL to stratospheric ozone depletion by contrasting ensembles of historical integrations with and without a realistic ozone hole. In the presence of very large natural variability, the robustness of the ozone impact on the ASL is established by (1) examining ensembles of model runs to isolate the forced response, (2) repeating the analysis with two different climate models, and (3) considering the entire period of stratospheric ozone depletion, the beginning of which predates the satellite era by a couple of decades.

  11. Ocean measurements in the Amundsen Sea, Nathaniel B. Palmer Cruise 09-01, 05 January - 28 February 2009 (NODC Accession 0071179)

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    National Oceanic and Atmospheric Administration, Department of Commerce — We are reporting ocean pressure, temperature, salinity and dissolved oxygen data from 160 CTD/O stations occupied in the Amundsen Sea. These austral summer...

  12. Ice-shelf height variability in Amundsen Sea linked to ENSO

    Science.gov (United States)

    Paolo, Fernando; Fricker, Helen; Padman, Laurie

    2016-04-01

    Atmospheric and sea-ice conditions around Antarctica, particularly in the Amundsen and Bellingshausen seas, respond to climate dynamics in the tropical Pacific Ocean on interannual time scales including the El Nino-Southern Oscillation (ENSO). It has been hypothesized that the mass balance of the Antarctic Ice Sheet, including its floating ice shelves, also responds to this climate signal; however, this has not yet been unambiguously demonstrated. We apply multivariate singular spectrum analysis (MSSA) to 18-year (1994-2012) time series of ice-shelf height derived from satellite radar altimetry in the Amundsen Sea (AS) region. This advanced spectral method distinguishes between regular deterministic behavior ("cycles") at sub-decadal time scale and irregular behavior ("noise") at shorter time scales. Although the long-term trends in ice-shelf height change are much larger than the range of interannual variability in the AS region, the short-term rate of change dh/dt can vary about the trend by more than 50%. We extract the principal modes of variability (EOFs) based on common spectral properties from a set of 140 height time series. The mode of interannual variability in the AS ice-shelf height is strongly correlated with the low-frequency mode of ENSO (periodicity of ~4.5 years) as represented by the Southern Oscillation Index. This interannual mode in ice-shelf height, represented by the two leading EOFs, is responsible for about 25% of the variance in the de-trended data set. The ice-shelf height in the AS is expected to respond to changes in precipitation and inflows of warm subsurface Circumpolar Deep Water (CDW) into the ocean cavities under the ice shelves, altering basal melt rates. While we find a correlation between modeled precipitation anomalies and ice-shelf height, we are investigating (a) errors in model precipitation, (b) radar backscatter and firn-density issues, and (c) ocean contribution correlated with atmosphere through wind-stress forcing. We

  13. Small phytoplankton contribution to the standing stocks and the total primary production in the Amundsen Sea

    Science.gov (United States)

    Lee, Sang H.; Kim, Bo Kyung; Lim, Yu Jeong; Joo, HuiTae; Kang, Jae Joong; Lee, Dabin; Park, Jisoo; Ha, Sun-Yong; Lee, Sang Hoon

    2017-08-01

    Small phytoplankton are anticipated to be more important in a recently warming and freshening ocean condition. However, little information on the contribution of small phytoplankton to overall phytoplankton production is currently available in the Amundsen Sea. To determine the contributions of small phytoplankton to total biomass and primary production, carbon and nitrogen uptake rates of total and small phytoplankton were obtained from 12 productivity stations in the Amundsen Sea. The daily carbon uptake rates of total phytoplankton averaged in this study were 0.42 g C m-2 d-1 (SD = ± 0.30 g C m-2 d-1) and 0.84 g C m-2 d-1 (SD = ± 0.18 g C m-2 d-1) for non-polynya and polynya regions, respectively, whereas the daily total nitrogen (nitrate and ammonium) uptake rates were 0.12 g N m-2 d-1 (SD = ± 0.09 g N m-2 d-1) and 0.21 g N m-2 d-1 (SD = ± 0.11 g N m-2 d-1), respectively, for non-polynya and polynya regions, all of which were within the ranges reported previously. Small phytoplankton contributed 26.9 and 27.7 % to the total carbon and nitrogen uptake rates of phytoplankton in this study, respectively, which were relatively higher than the chlorophyll a contribution (19.4 %) of small phytoplankton. For a comparison of different regions, the contributions for chlorophyll a concentration and primary production of small phytoplankton averaged from all the non-polynya stations were 42.4 and 50.8 %, which were significantly higher than those (7.9 and 14.9 %, respectively) in the polynya region. A strong negative correlation (r2 = 0. 790, p<0. 05) was found between the contributions of small phytoplankton and the total daily primary production of phytoplankton in this study. This finding implies that daily primary production decreases as small phytoplankton contribution increases, which is mainly due to the lower carbon uptake rate of small phytoplankton than large phytoplankton.

  14. Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula

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    Hugh W. Ducklow

    2015-04-01

    Full Text Available Abstract We report results from a yearlong, moored sediment trap in the Amundsen Sea Polynya (ASP, the first such time series in this remote and productive ecosystem. Results are compared to a long-term (1992–2013 time series from the western Antarctic Peninsula (WAP. The ASP trap was deployed from December 2010 to December 2011 at 350 m depth. We observed two brief, but high flux events, peaking at 8 and 5 mmol C m−2 d−1 in January and December 2011, respectively, with a total annual capture of 315 mmol C m−2. Both peak fluxes and annual capture exceeded the comparable WAP observations. Like the overlying phytoplankton bloom observed during the cruise in the ASP (December 2010 to January 2011, particle flux was dominated by Phaeocystis antarctica, which produced phytodetrital aggregates. Particles at the start of the bloom were highly depleted in 13C, indicating their origin in the cold, CO2-rich winter waters exposed by retreating sea ice. As the bloom progressed, microscope visualization and stable isotopic composition provided evidence for an increasing contribution by zooplankton fecal material. Incubation experiments and zooplankton observations suggested that fecal pellet production likely contributed 10–40% of the total flux during the first flux event, and could be very high during episodic krill swarms. Independent estimates of export from the surface (100 m were about 5–10 times that captured in the trap at 350 m. Estimated bacterial respiration was sufficient to account for much of the decline in the flux between 50 and 350 m, whereas zooplankton respiration was much lower. The ASP system appears to export only a small fraction of its production deeper than 350 m within the polynya region. The export efficiency was comparable to other polar regions where phytoplankton blooms were not dominated by diatoms.

  15. Modeling the Spreading of Glacial Melt Water from the Amundsen and Bellingshausen Seas

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    Nakayama, Y.; Timmermann, R.; Rodehacke, C. B.; Schröder, M.; Hellmer, H. H.

    2014-12-01

    The ice shelves and glaciers of the West Antarctic Ice Sheet (WAIS) are rapidly thinning, especially in the Amundsen Sea (AS) and Bellingshausen Sea (BS). The high basal melting of these small ice shelves is caused by relatively warm Circumpolar Deep Water (CDW) that, based on observations, mainly intrudes via two submarine glacial troughs located at the eastern and central AS continental shelf break. When CDW reaches the grounding line of the fringing glaciers, it melts the glaciers and forms buoyant melt water plumes. As the glacial melt becomes part of the AS shelf circulation, it may cause a freshening of the shelf water locally as well as remotely in the Ross Sea (RS). To test whether the observed freshening of the RS is a consequence of the enhanced basal melting of AS ice shelves, we use Finite-Element Sea-ice/ice-shelf/Ocean Model (FESOM) with a horizontal resolution of 2-10 km on the AS and BS continental shelves. The model is forced with 6-hourly atmospheric data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) for the period 1979-1988. The model results show bottom temperatures in the AS and BS close to observations, and basal melt rates of AS and BS ice shelves consistent with other observation-based estimates. Using several independent virtual passive tracers to identify pathways of the glacial melt, we find that the melt water from the ice shelves in the AS flows towards the Ross Ice Shelf front. After 10 years of simulation, about half of the melt water in the Ross Sea originates from the Getz Ice Shelf. Further, we investigate the sensitivity of the melt water transport into the RS associated with the strength of the basal melt water flux. When this flux is increased by 30%, the transport of glacial melt into the RS more than doubles, supporting the idea that the basal melting of AS and BS ice shelves is one of the main reasons for the freshening of the RS continental shelf.

  16. The distribution of glacial meltwater in the Amundsen Sea, Antarctica, revealed by dissolved helium and neon

    Science.gov (United States)

    Kim, Intae; Hahm, Doshik; Rhee, Tae Siek; Kim, Tae Wan; Kim, Chang-Sin; Lee, SangHoon

    2016-03-01

    The light noble gases, helium (He) and neon (Ne), dissolved in seawater, can be useful tracers of freshwater input from glacial melting because the dissolution of air bubbles trapped in glacial ice results in an approximately tenfold supersaturation. Using He and Ne measurements, we determined, for the first time, the distribution of glacial meltwater (GMW) within the water columns of the Dotson Trough (DT) and in front of the Dotson and Getz Ice Shelves (DIS and GIS, respectively) in the western Amundsen Sea, Antarctica, in the austral summers of 2011 and 2012. The measured saturation anomalies of He and Ne (ΔHe and ΔNe) were in the range of 3-35% and 2-12%, respectively, indicating a significant presence of GMW. Throughout the DT, the highest values of ΔHe (21%) were observed at depths of 400-500 m, corresponding to the layer between the incoming warm Circumpolar Deep Water and the overlying Winter Water. The high ΔHe (and ΔNe) area extended outside of the shelf break, suggesting that GMW is transported more than 300 km offshore. The ΔHe was substantially higher in front of the DIS than the GIS, and the highest ΔHe (31%) was observed in the western part of the DIS, where concentrated outflow from the shelf to the offshore was observed. In 2012, the calculated GMW fraction in seawater based on excess He and Ne decreased by 30-40% compared with that in 2011 in both ice shelves, indicating strong temporal variability in glacial melting.

  17. Climatología de la variabilidad espacial de la concentración de hielo en los mares de Bellingshausen, Amundsen y Weddell Climatology of sea ice concentration spatial variability over Bellingshausen, Amundsen and Weddell Seas

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    Rosa H. Compagnucci

    2005-12-01

    ártica, muestran un cambio de comportamiento ocurrido a fines de los años 80s, en que los mares de Amundsen y Bellingshausen pasaron de tener mayores a menores concentraciones de hielo marino. La distribución espacial de ACHM durante las fases maduras tanto de El Niño muestra una gran variabilidad entre eventos y en algunos casos tiene comportamiento opuesto para diferentes eventos. Lo mismo ocurre para La Niña. La influencia del ciclo El Niño/Oscilación del Sur es clara solo para el invierno que sigue a la fase madura estival del El Niño o La Niña.In this paper the most frequent spatial patterns of sea ice concentration anomalies (SICA over the Amundsen, Bellingshausen and Weddell Seas have been obtained from monthly mean values of sea ice concentrations provided by the Scanning Multichannel Microwave Radiometer and the Special Sensor Microwave/Imager of NASA Goddard Space Flight Center for the period 1979 2000. Using analysis of Principal Components (PCs in T-Mode rotated Varimax, six PCs were obtained. Therefore, a total of 12 patterns were found with six in direct mode (SICA of the same sign that the PC and six in inversely (SICA of opposite sign to the PC, that classify 95.5 % of the monthly fields. Three PCs describe the most frequent winter-spring cases (period with major concentration and expansion of sea ice and three PCs correspond to summer-autumn (minor concentration and retraction of the field of ice. Winter-spring months have mainly situations close to the first and second PCs. The 2°PC shows a 30 ° counter wise rotation with respect to the 1°CP and both present dipole anomalies between the seas at both sides of the Antarctic Peninsula. These two components display a recurrence of approximately 4 years in which alternatively the exterior region of the Weddell Sea has conditions of sea ice above the mean values meanwhile, in the north of the Amundsen Sea, the anomalies are negative and vice versa. The most frequent condition with an annual summer - autumn

  18. Fe availability drives phytoplankton photosynthesis rates during spring bloom in the Amundsen Sea Polynya, Antarctica

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    Anne-Carlijn Alderkamp

    2015-04-01

    Full Text Available Abstract To evaluate what drives phytoplankton photosynthesis rates in the Amundsen Sea Polynya (ASP, Antarctica, during the spring bloom, we studied phytoplankton biomass, photosynthesis rates, and water column productivity during a bloom of Phaeocystis antarctica (Haptophyceae and tested effects of iron (Fe and light availability on these parameters in bioassay experiments in deck incubators. Phytoplankton biomass and productivity were highest (20 µg chlorophyll a L−1 and 6.5 g C m−2 d−1 in the central ASP where sea ice melt water and surface warming enhanced stratification, reducing mixed layer depth and increasing light availability. In contrast, maximum photosynthesis rate (P*max, initial light-limited slope of the photosynthesis–irradiance curve (α*, and maximum photochemical efficiency of photosystem II (Fv/Fm were highest in the southern ASP near the potential Fe sources of the Dotson and Getz ice shelves. In the central ASP, P*max, α*, and Fv/Fm were all lower. Fe addition increased phytoplankton growth rates in three of twelve incubations, and at a significant level when all experiments were analyzed together, indicating Fe availability may be rate-limiting for phytoplankton growth in several regions of the ASP early in the season during build-up of the spring bloom. Moreover, Fe addition increased P*max, α*, and Fv/Fm in almost all experiments when compared to unamended controls. Incubation under high light also increased P*max, but decreased Fv/Fm and α* when compared to low light incubation. These results indicate that the lower values for P*max, α*, and Fv/Fm in the central ASP, compared to regions close to the ice shelves, are constrained by lower Fe availability rather than light availability. Our study suggests that higher Fe availability (e.g., from higher melt rates of ice shelves would increase photosynthesis rates in the central ASP and potentially increase water column productivity 1.7-fold, making the ASP

  19. Stepped Holocene sea-level rise and its influence on sedimentation in a large marine embayment: Maputo Bay, Mozambique

    Science.gov (United States)

    De Lecea, A. M.; Green, A. N.; Strachan, K. L.; Cooper, J. A. G.; Wiles, E. A.

    2017-07-01

    The sedimentary record in large marine embayments holds important information on Holocene environmental and sea-level changes. This paper investigates the evolution of a large subtropical marine embayment, Maputo Bay, in southern Mozambique. Using a combination of sediment cores, stable isotope data, seismic reflection profiling and 14C dating, we show complex back-barrier changes during the Holocene and link these to stepped rises in sea level. Our data reveal a sea-level ;slowstand; followed by an abrupt rise that we correlate with the 8.2 ka global rise in sea level. Sedimentological, isotope and seismic evidence point to a subsequent slowstand interspersed by two punctuated rises in sea level that formed clear tidal ravinement surfaces. Sedimentary changes in the embayment are primarily forced by sea-level change, whereby tidal ravinement surfaces sandwich normal regressive packages formed via marginal progradation and shallowing of the system during ;slow-; or still-stands. Large marine embayment systems hold great potential in unravelling relative sea-level change. Axiomatically, this reduces their utility as archives of climate-change.

  20. An unusual early Holocene diatom event north of the Getz Ice Shelf (Amundsen Sea): Implications for West Antarctic Ice Sheet development

    Science.gov (United States)

    Esper, O.; Gersonde, R.; Hillenbrand, C.; Kuhn, G.; Smith, J.

    2011-12-01

    Modern global change affects not only the polar north but also, and to increasing extent, the southern high latitudes, especially the Antarctic regions covered by the West Antarctic Ice Sheet (WAIS). Consequently, knowledge of the mechanisms controlling past WAIS dynamics and WAIS behaviour at the last deglaciation is critical to predict its development in a future warming world. Geological and palaeobiological information from major drainage areas of the WAIS, like the Amundsen Sea Embayment, shed light on the history of the WAIS glaciers. Sediment records obtained from a deep inner shelf basin north of Getz Ice Shelf document a deglacial warming in three phases. Above a glacial diamicton and a sediment package barren of microfossils that document sediment deposition by grounded ice and below an ice shelf or perennial sea ice cover (possibly fast ice), respectively, a sediment section with diatom assemblages dominated by sea ice taxa indicates ice shelf retreat and seasonal ice-free conditions. This conclusion is supported by diatom-based summer temperature reconstructions. The early retreat was followed by a phase, when exceptional diatom ooze was deposited around 12,500 cal. years B.P. [1]. Microscopical inspection of this ooze revealed excellent preservation of diatom frustules of the species Corethron pennatum together with vegetative Chaetoceros, thus an assemblage usually not preserved in the sedimentary record. Sediments succeeding this section contain diatom assemblages indicating rather constant Holocene cold water conditions with seasonal sea ice. The deposition of the diatom ooze can be related to changes in hydrographic conditions including strong advection of nutrients. However, sediment focussing in the partly steep inner shelf basins cannot be excluded as a factor enhancing the thickness of the ooze deposits. It is not only the presence of the diatom ooze but also the exceptional preservation and the species composition of the diatom assemblage

  1. How does a tidal embayment morphodynamically react on sea level rise?

    Science.gov (United States)

    van der Wegen, Mick

    2010-05-01

    Conditions for (assumed) equilibrium in tidal embayments have been studied extensively in the past years with morphodynamic 1D models (Van Dongeren and De Vriend, 1994; Schuttelaars and de Swart, 1996, 2000; Lanzoni and Seminara, 2002) and 2D models (Hibma et al. [2003], Van der Wegen and Roelvink [2008]) Van der Wegen et al 2008). The current research addresses the impact of sea level rise on tidal embayments. Although effects of sea level rise may only become apparent after decades, the character of the embayment can change considerably. Examples are the (dis)appearance or re-allocation of intertidal flats, increased tidal resonance, shift from sediment export to import, deepening of channel area and other related (ecological) parameters. The research applies a 2D morphodynamic model (Delft3D) in an idealized environment. The model is based on the 2 D shallow water equations, the Engelund -Hansen transport formula and includes bed slope effects, drying and flooding procedures and an advanced morphodynamic update scheme (Roelvink 2006). The initial condition of the bathymetry is generated by 3000 years of morphodynamic calculations in a 80 km long and 2.5 km wide rectangular tidal embayment under constant M2 tidal forcing conditions (Van der Wegen and Roelvink [2008]). After this period sea level rise gradually developing towards a rate of 0.4 m/century is added to the boundary conditions. Model results describe development towards less intertidal area and a transition from an exporting system to a importing system. Model results are evaluated in terms of M2, M4 and M6 tidal constituents as well as against Vs/Vc (shoal volume over channel volume) versus a/h (amplitude over water depth) relationship as proposed by Friedrichs and Aubrey (1988). Although the model describes morphodynamic development in a strongly idealized environment the results can provide an excellent tool to systematically study the impact of sea level rise in tidal embayments as well as the time

  2. Summer and Fall Sea Ice Processes in the Amundsen Sea: Bottom melting, surface flooding and snow ice formation

    Science.gov (United States)

    Ackley, S. F.; Perovich, D. K.; Weissling, B.; Elder, B. C.

    2011-12-01

    Two ice mass balance buoys were deployed on the Amundsen Sea, Antarctica, ice pack near January 1, 2011. Below freezing air and snow temperatures and sea ice and seawater temperatures at the freezing point at this time indicated that summer melt had not yet commenced. Over the next two months, however, while snow depths changed by less than 0.1m, ice thickness decreased, from bottom melting, by 0.9-1.0m. As snow temperature records did not show temperatures ever reaching the melting point, no surface melt was recorded during the summer period and the small snow depth changes were presumed to occur by consolidation or wind scouring. Water temperatures above the freezing point caused the observed bottom melting from mid January to late February. During the ice loss periods, progressive flooding by sea water at the base of the snow pack was recorded by temperature sensors, showing an increase in the depth of flooded snow pack of 0.4m by the end of the summer period in late February. We hypothesize that progressive flooding of the surface snow pack gives a mechanism for nutrient replenishment in these upper layers, and continuous high algal growth can therefore occur in the flooded snow layer during summer. An underice radiometer recorded light transmission through the ice and snow at selective wavelengths sensitive to chlorophyll. These radiometric results will be presented to examine this algal growth hypothesis. This flooded layer then refroze from the top down into snow ice as air temperatures dropped during March and April, showing that the layer had refrozen as snow ice on the top surface of the ice. Refreezing of the flooded layer gives an ice growth mechanism at the end of summer of 0.2 m to 0.4m of new ice growth over the majority of the ice pack. The snow ice growth in areas covered with pack ice gives salt fluxes commensurate with new ice growth in the autumn expansion of the ice edge over open water. These high salt fluxes therefore represent a marked

  3. Amundsen Sea sector ice shelf thickness, melt rates, and inland response from annual high-resolution DEM mosaics

    Science.gov (United States)

    Shean, D. E.; Joughin, I. R.; Smith, B. E.; Alexandrov, O.; Moratto, Z.; Porter, C. C.; Morin, P. J.

    2014-12-01

    Significant grounding line retreat, acceleration, and thinning have occurred along the Amundsen Sea sector of West Antarctica in recent decades. These changes are driven primarily by ice-ocean interaction beneath ice shelves, but existing observations of the spatial distribution, timing, and magnitude of ice shelf melt are limited. Using the NASA Ames Stereo Pipeline, we generated digital elevation models (DEMs) with ~2 m posting from all ~450 available WorldView-1/2 along-track stereopairs for the Amundsen Sea sector. A novel iterative closest point algorithm was used to coregister DEMs to filtered Operation IceBridge ATM/LVIS data and ICESat-1 GLAS data, offering optimal sub-meter horizontal/vertical accuracy. The corrected DEMs were used to produce annual mosaics for the entire ~500x700 km region with focused, sub-annual products for ice shelves and grounding zones. These mosaics provide spatially-continuous measurements of ice shelf topography with unprecedented detail. Using these data, we derive estimates of ice shelf thickness for regions in hydrostatic equilibrium and map networks of sub-shelf melt channels for the Pine Island (PIG), Thwaites, Crosson, and Dotson ice shelves. We also document the break-up of the Thwaites ice shelf and PIG rift evolution leading up to the 2013 calving event. Eulerian difference maps document 2010-2014 thinning over fast-flowing ice streams and adjacent grounded ice. These data reveal the greatest thinning rates over the Smith Glacier ice plain and slopes beyond the margins of the fast-flowing PIG trunk. Difference maps also highlight the filling of at least two subglacial lakes ~30 km upstream of the PIG grounding line in 2011. Lagrangian difference maps reveal the spatial distribution of ice shelf thinning, which can primarily be attributed to basal melt. Preliminary results show focused ice shelf thinning within troughs and large basal channels, especially along the western margin of the Dotson ice shelf. These new data

  4. Bathymetry of the Amundsen Sea Embayment sector of West Antarctica from Operation IceBridge gravity and other data

    Science.gov (United States)

    Millan, Romain; Rignot, Eric; Bernier, Vincent; Morlighem, Mathieu; Dutrieux, Pierre

    2017-02-01

    We employ airborne gravity data from NASA's Operation IceBridge collected in 2009-2014 to infer the bathymetry of sub-ice shelf cavities in front of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica. We use a three-dimensional inversion constrained by multibeam echo sounding data offshore and bed topography from a mass conservation reconstruction on land. The seamless bed elevation data refine details of the Pine Island sub-ice shelf cavity, a slightly thinner cavity beneath Thwaites, and previously unknown deep (>1200 m) channels beneath the Crosson and Dotson ice shelves that shallow (500 m and 750 m, respectively) near the ice shelf fronts. These sub-ice shelf channels define the natural pathways for warm, circumpolar deep water to reach the glacier grounding lines, melt the ice shelves from below, and constrain the pattern of past and future glacial retreat.

  5. Origin and fate of particulate organic matter in the southern Beaufort Sea - Amundsen Gulf region, Canadian Arctic

    DEFF Research Database (Denmark)

    Magen, Cedric; Chaillou, Gwenaelle; Crowe, Sean;

    2010-01-01

    To establish the relative importance of terrigenous and marine organic matter in the southern Beaufort Sea, we measured the concentrations and the stable isotopic compositions of organic carbon and total nitrogen in sediments and in settling particles intercepted by sediment traps. The organic ca....... This process continues in the bottom sediment with the result that the sedimentary organic matter becomes dominated by the refractory terrigenous and marine components. (C) 2009 Elsevier Ltd. All rights reserved.......To establish the relative importance of terrigenous and marine organic matter in the southern Beaufort Sea, we measured the concentrations and the stable isotopic compositions of organic carbon and total nitrogen in sediments and in settling particles intercepted by sediment traps. The organic......) in the sediment samples were strongly correlated, with the highest values, indicative of a more marine contribution, in the Amundsen Gulf In contrast, the organic matter content, elemental (CORG:NTOT ratio) and isotopic (delta C-13(ORG); and delta N-15(TOT)) composition of the settling particles was different...

  6. Is Ekman pumping responsible for the seasonal variation of warm circumpolar deep water in the Amundsen Sea?

    Science.gov (United States)

    Kim, T. W.; Ha, H. K.; Wåhlin, A. K.; Lee, S. H.; Kim, C. S.; Lee, J. H.; Cho, Y. K.

    2017-01-01

    Ekman pumping induced by horizontally varying wind and sea ice drift is examined as an explanation for observed seasonal variation of the warm layer thickness of circumpolar deep water on the Amundsen Sea continental shelf. Spatial and temporal variation of the warm layer thickness in one of the deep troughs on the shelf (Dotson Trough) was measured during two oceanographic surveys and a two-year mooring deployment. A hydrographic transect from the deep ocean, across the shelf break, and into the trough shows a local elevation of the warm layer at the shelf break. On the shelf, the water flows south-east along the trough, gradually becoming colder and fresher due to mixing with cold water masses. A mooring placed in the trough shows a thicker and warmer layer in February and March (late summer/early autumn) and thinner and colder layer in September, October and November (late winter/early spring). The amplitude of this seasonal variation is up to 60 m. In order to investigate the effects of Ekman pumping, remotely sensed wind (Antarctic Mesoscale Prediction System wind data) and sea ice velocity and concentration (EASE Polar Pathfinder) were used. From the estimated surface stress field, the Ekman transport and Ekman pumping were calculated. At the shelf break, where the warm layer is elevated, the Ekman pumping shows a seasonal variation correlating with the mooring data. Previous studies have not been able to show a correlation between observed wind and bottom temperature, but it is shown here that when sea ice drift is taken into account the Ekman pumping at the outer shelf correlates with bottom temperature in Dotson Trough. The reason why the Ekman pumping varies seasonally at the shelf break appears to be the migration of the ice edge in the expanding polynya in combination with the wind field which on average is westward south of the shelf break.

  7. Using modelling to predict impacts of sea level rise and increased turbidity on seagrass distributions in estuarine embayments

    Science.gov (United States)

    Davis, Tom R.; Harasti, David; Smith, Stephen D. A.; Kelaher, Brendan P.

    2016-11-01

    Climate change induced sea level rise will affect shallow estuarine habitats, which are already under threat from multiple anthropogenic stressors. Here, we present the results of modelling to predict potential impacts of climate change associated processes on seagrass distributions. We use a novel application of relative environmental suitability (RES) modelling to examine relationships between variables of physiological importance to seagrasses (light availability, wave exposure, and current flow) and seagrass distributions within 5 estuarine embayments. Models were constructed separately for Posidonia australis and Zostera muelleri subsp. capricorni using seagrass data from Port Stephens estuary, New South Wales, Australia. Subsequent testing of models used independent datasets from four other estuarine embayments (Wallis Lake, Lake Illawarra, Merimbula Lake, and Pambula Lake) distributed along 570 km of the east Australian coast. Relative environmental suitability models provided adequate predictions for seagrass distributions within Port Stephens and the other estuarine embayments, indicating that they may have broad regional application. Under the predictions of RES models, both sea level rise and increased turbidity are predicted to cause substantial seagrass losses in deeper estuarine areas, resulting in a net shoreward movement of seagrass beds. Seagrass species distribution models developed in this study provide a valuable tool to predict future shifts in estuarine seagrass distributions, allowing identification of areas for protection, monitoring and rehabilitation.

  8. Meso- and macro-zooplankton community structure of the Amundsen Sea Polynya, Antarctica (Summer 2010–2011

    Directory of Open Access Journals (Sweden)

    Stephanie E. Wilson

    2015-01-01

    Full Text Available Abstract The Amundsen Sea Polynya (ASP has, on average, the highest productivity per unit area in Antarctic waters. To investigate community structure and the role that zooplankton may play in utilizing this productivity, animals were collected at six stations inside and outside the ASP using paired “day-night” tows with a 1 m2 MOCNESS. Stations were selected according to productivity based on satellite imagery, distance from the ice edge, and depth of the water column. Depths sampled were stratified from the surface to ∼ 50–100 m above the seafloor. Macrozooplankton were also collected at four stations located in different parts of the ASP using a 2 m2 Metro Net for krill surface trawls (0–120 m. The most abundant groups of zooplankton were copepods, ostracods, and euphausiids. Zooplankton biovolume (0.001 to 1.22 ml m-3 and abundance (0.21 to 97.5 individuals m-3 varied throughout all depth levels, with a midsurface maximum trend at ∼ 60–100 m. A segregation of increasing zooplankton trophic position with depth was observed in the MOCNESS tows. In general, zooplankton abundance was low above the mixed layer depth, a result attributed to a thick layer of the unpalatable colonial haptophyte, Phaeocystis antarctica. Abundances of the ice krill, Euphausia crystallarophias, however, were highest near the edge of the ice sheet within the ASP and larvae:adult ratios correlated with temperature above a depth of 60 m. Total zooplankton abundance correlated positively with chlorophyll a above 150 m, but negative correlations observed for biovolume vs. the proportion of P. antarctica in the phytoplankton estimated from pigment ratios (19’hexanoyloxyfucoxanthin:fucoxanthin again pointed to avoidance of P. antarctica. Quantifying zooplankton community structure, abundance, and biovolume (biomass in this highly productive polynya helps shed light on how carbon may be transferred to higher trophic levels and to depth in a region undergoing

  9. Distributions of dimethyl sulfide in the Amundsen Sea water column, Antarctica, measured by membrane inlet mass spectrometer

    Science.gov (United States)

    KIM, I.; Park, K.; Hahm, D.; Choi, J. O.; Lee, S.

    2016-12-01

    Dimethyl sulfide (DMS), as important precursor of cloud condensation nuclei (CCN), directly affects the radioactive budget and resultant climate feedback. Because the oceanic emission is a major natural source of atmospheric DMS, it is fundamental to better understand the factors that controlling oceanic DMS cycle. Antarctic polynya, especially, can be a key source region of DMS due to high productivity and vast surface area. However, its observations are evidently lacked due to the limited accessibility of polar ocean, and thus, significance of DMS flux in Southern Ocean is still underestimated. Membrane inlet mass spectrometry (MIMS) technique directly samples analyte gases from the aqueous phase gases in seawater through a semi-permeable membrane. Since this method does not require headspace equilibration, MIMS enables us to make a near-real time, high frequency continuous observation of dissolved gases. In this study, we have investigated the horizontal- (underway) and vertical (discrete bottle samples) distributions DMS in the upper water column of entire Amundsen Sea in austral summer (Jan. Feb. 2016) using MIMS on the Korean icebreaker R/V Araon. The concentrations of DMS in surface water near ice shelf regions (Dotson and Getz ice shelf) were higher than that in polynya center along DT, which is conflict with the precious result from 2009 observation by Tortell et al. (2012) The highest concentrations of DMS (up to >300 nM) in the were observed in the polyna mouth and near Getz ice shelf surface. The overall trends of DMS were consistent with those of chlorophyll and ΔO2/Ar (as indicators of net community production). The spatial variability of DMS seems to be attributed to a phytoplankton composition, such as competition between Phaeocystis and other diatoms. These results imply that the biological process of P. Antarctica bloom provoke the significant emissions of algal metabolite dimethylsulfonioproprionate (DMSP) and resultant DMS.

  10. Cultivation and biochemical characterization of heterotrophic bacteria associated with phytoplankton bloom in the Amundsen sea polynya, Antarctica

    Science.gov (United States)

    Choi, Seon-Bin; Kim, Jong-Geol; Jung, Man-Young; Kim, So-Jeong; Min, Ui-Gi; Si, Ok-Ja; Park, Soo-Je; Yeon Hwang, Chung; Park, Jisoo; Lee, SangHoon; Rhee, Sung-Keun

    2016-01-01

    Polynyas are a key ecosystem for carbon cycling in the Antarctic Ocean due to the intensive primary production. Most of the knowledge regarding the bacterioplankton community in the Antarctic Ocean that is responsible for re-mineralization of fixed carbon comes from metagenomic analyses. Here, the extinction-dilution method was used to obtain representative heterotrophs from a polynya in the Amundsen Sea, Antarctica, and their biochemical potential for carbon re-mineralization were assessed. All 23 strains have close relatives belonging to type strains within the following genera (number of strains; % 16S rRNA gene sequence similarity): Bizionia (4; >97.8%), Leeuwenhoekiella (1; 96.2%), Pseudoalteromonas (14; >98.5%), Pseudomonas (1; 99.4%) and Sulfitobacter (3; 100%), which were also observed in 454 pyrosequencing-based analysis of 16S rRNA gene sequences of the polynya. Although sequence reads related to Polaribacter were the most common, Polaribacter strains could only be obtained from colonies cultured on agar plates. The strain of Leeuwenhoekiella showed a prominent ability in hydrolyzing diverse esters, amides, and glycosides while the strains of Pseudoalteromonas, Polaribacter, and Bizionia showed extracellular enzyme activities only on a narrow range of amides. The strains of Leeuwenhoekiella, Pseudoalteromonas, and Sulfitobacter utilized various labile carbon sources: carbohydrates, organic acids, amino acids, and peptides. The most frequent isolates, strains of Pseudoaltermonas, showed marked differences in terms of their potential to utilize different types of labile carbon sources, which may reflect high genomic diversity. The strains of Bizionia and Pseudomonas did not utilize carbohydrates. Unique biochemical properties associated with extracellular hydrolase activities and labile carbon utilization were revealed for dominant culturable heterotrophs which gives insights into their roles in active re-mineralization of fixed carbons in polynya.

  11. Ice shelf-ocean interactions, mechanisms of change in the Amundsen Sea, West Antarctica

    Science.gov (United States)

    Dutrieux, P.

    2015-12-01

    Over the length of the observational record, the Antarctic Ice Sheet has been loosing ice to the ocean, significantly contributing to global sea level rise. This signal is largely due to glacial flow acceleration in West Antarctica, driven by oceanic melting at its margin and the induced thinning of the glacier buttressing ice shelves. Pine Island Glacier is one stellar example where vigorous oceanic melting fundamentally modifies the geometry of the ice-ocean interface and the associated ice dynamics. Since the early 1970's, the glacier terminating ice shelf has thinned, its grounding line has retreated, and its speed has doubled, now reaching close to 11 m/day. During that time, oceanic melting has increased, injecting fresh and nutrient-rich waters between the surface and intermediate depth in the coastal southern ocean. Using autonomous platforms, ship-borne ocean observations, ground-based and airborne radar observations, satellite observations and numerical modelling, this talk will review the mechanisms behind this trajectory of change and open perspectives on its potential impacts in the Southern Ocean.

  12. Reconstructing the Last Glacial Maximum ice sheet in the Weddell Sea embayment, Antarctica, using numerical modelling constrained by field evidence

    Science.gov (United States)

    Le Brocq, A. M.; Bentley, M. J.; Hubbard, A.; Fogwill, C. J.; Sugden, D. E.; Whitehouse, P. L.

    2011-09-01

    The Weddell Sea Embayment (WSE) sector of the Antarctic ice sheet has been suggested as a potential source for a period of rapid sea-level rise - Meltwater Pulse 1a, a 20 m rise in ˜500 years. Previous modelling attempts have predicted an extensive grounding line advance in the WSE, to the continental shelf break, leading to a large equivalent sea-level contribution for the sector. A range of recent field evidence suggests that the ice sheet elevation change in the WSE at the Last Glacial Maximum (LGM) is less than previously thought. This paper describes and discusses an ice flow modelling derived reconstruction of the LGM ice sheet in the WSE, constrained by the recent field evidence. The ice flow model reconstructions suggest that an ice sheet consistent with the field evidence does not support grounding line advance to the continental shelf break. A range of modelled ice sheet surfaces are instead produced, with different grounding line locations derived from a novel grounding line advance scheme. The ice sheet reconstructions which best fit the field constraints lead to a range of equivalent eustatic sea-level estimates between approximately 1.4 and 3 m for this sector. This paper describes the modelling procedure in detail, considers the assumptions and limitations associated with the modelling approach, and how the uncertainty may impact on the eustatic sea-level equivalent results for the WSE.

  13. The New Britain trench and 149° embayment, Western Solomon Sea

    Science.gov (United States)

    Tiffin, D. L.; Davies, H. L.; Honza, E.; Lock, J.; Okuda, Y.

    1987-09-01

    The western New Britain Trench contains relatively thin sediment fill in the east, compared to the west where a sequence of thick turbidites is ponded behind a basement high in the trench axis, The trench trends toward Huon Gulf, but intersects the Trobriand Trench at an acute angle at the 149° Embayment, where both trenches end. Seismic structure west of the trench is incoherent, related to incipient collision of the Indian-Australia Plate and the South Bismarck Plate. The collision suture is marked by the Markham Canyon, continuous in its upper reaches with the Ramu-Markham Fault Zone on shore.

  14. Climate-sensitive carbon cycling on the western Antarctic continental shelf: results from the Amundsen Sea Polynya International Research Expedition (ASPIRE)

    Science.gov (United States)

    Yager, P. L.; Sherrell, R. M.; Stammerjohn, S. E.

    2016-02-01

    The Amundsen Sea hosts the most productive polynya in all of coastal Antarctica, with its vibrant green waters exceeding 20 µg Chl a per liter. It is also one of the global regions most vulnerable to climate change, experiencing rapid losses in both sea ice cover and nearby ice sheets. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010-11, we aimed to determine mechanisms driving the production and fate of this extraordinary algal bloom, with an eye towards predicting how this system will respond to further change. Here we summarize and synthesize results from the expedition, highlight results now being published in a special ASPIRE feature in the journal Elementa, and present an effort to balance the carbon budget for the region. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, macrozooplankton, and microbial biomass. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated nitrate depletion, changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m-2) and gas exchange are compared to nutrient and organic matter inventories to estimate export. Comparisons to short-term (days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a high fraction (up to 60%) of the net community production was exported to sub-euphotic depths during the early part of the bloom in this productive region. The ultimate fate of this carbon is also estimated. We discuss the importance of this carbon sequestration, particularly in light of changing climate conditions in this region, informed by ongoing data synthesis and modeling efforts (INSPIRE).

  15. Application of Multi-well Subsidence Analysis of the Beryl Embayment,Viking Graben, Northern North Sea

    Institute of Scientific and Technical Information of China (English)

    DOU Lirong; Jon D.TURNER; Roger A.SCRUTTON

    2006-01-01

    The Beryl Embayment is situated at the south end of the North Viking Graben in the North Sea. Three sets of normal faults, with N-S, NW-SE and NE-SW orientations, have been recognized in the Beryl Embayment. High-resolution subsidence analysis of 73 wells, combined with some seismic data, has been used to document Middle to Late Jurassic subsidence patterns in this area. The high temporal resolution achieved (1 to 2 million years per data point) has also allowed an assessment to be made of temporal evolution of faults with different orientations, and a study made of how and when the East Shetland Fault was linked and controlled sedimentary facies distributions. The results indicate that the East Shetland Fault can be divided into northern and southern parts which were linked together during the Early-Mid Oxfordian. The Mid-Late Jurassic syn-rift phase can be divided into four stages: minor active extension stage during the Bathonian-Middle Callovian, early syn-rotational stage during the Late Callovian-Early-Mid Oxfordian, syn-rotational climax stage during the Late Oxfordian-Early Volgian, and late syn-rotational stage during the Mid-Late Volgian. The results also show that there was a sequential variation of extension direction of active normal faults with different orientations, with an overall shift in the dominant orientation of active normal faults from N-S in the Bathonian-Middle Oxfordian, through NNW-SSE in the Late Oxfordian-Early Volgian (≈N30°E), to NW-SE (≈N45°E) in the Mid-Late Volgian.

  16. A carbon budget for the Amundsen Sea Polynya, Antarctica: Estimating net community production and export in a highly productive polar ecosystem

    Directory of Open Access Journals (Sweden)

    PL Yager

    2016-12-01

    Full Text Available Abstract Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 µg L−1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE in austral summer 2010–11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozooplankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (ΔDIN; 0.027–0.74 mol N m−2, changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m−2 and gas exchange (0–1.7 mol C m−2 were combined to estimate early season net community production (sNCP; 0.2–5.9 mol C m−2 and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to ∼60% of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2–3 days drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3–6% of the export from ∼100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.

  17. Rates of N2 production and diversity and abundance of functional genes associated with denitrification and anaerobic ammonium oxidation in the sediment of the Amundsen Sea Polynya, Antarctica

    Science.gov (United States)

    Choi, Ayeon; Cho, Hyeyoun; Kim, Sung-Han; Thamdrup, Bo; Lee, SangHoon; Hyun, Jung-Ho

    2016-01-01

    A combination of molecular microbiological analyses and metabolic rate measurements was conducted to elucidate the diversity and abundance of denitrifying and anaerobic ammonium oxidation (anammox) bacteria and the nitrogen gas (N2) production rates in sediment underlying the highly productive polynya (Stns. 10 and 17) and the sea-ice zone on the outer shelf (Stn. 83) of the Amundsen Sea, Antarctica. Despite the high water column productivity, the N2 production rates by denitrification (0.04-0.31 nmol N cm-3sed. h-1) and anammox (0.13-0.26 nmol N cm-3 sed. h-1) were lower than those measured in other polar regions. In contrast, gene copy number (106-107 copies cm-3 of nirS and nosZ genes targeting denitirifiers and 105-107 copies cm-3 of 16S rRNA genes related to anammox bacteria) of the two bacterial groups at Stn. 17 was similar compared to those of other organic-rich environments. The majority of the nirS sequences were affiliated with Gammaproteobacteria (54% and 61% of the total nirS gene at Stns. 17 and 83, respectively), which were closely related to Pseudomonas aeruginosa. Most nosZ sequences (92% and 72% of the total nosZ genes at Stns. 17 and 83, respectively) were related to the Alphaproteobacteria, which were closely related to Ruegeria pomeroyi and Roseobacter denitrificans. Most (98%) of the sequences related to anammox bacteria were affiliated with Candidatus Scalindua at Stn. 17. Consequently, despite the low metabolic activity, the abundance and composition of most denitrifying and anammox bacteria detected from the ASP were similar to those reported from a variety of marine environments. Our results further imply that increased labile organic matter production resulting from a shift of the phytoplankton community from Phaeocystis to diatoms in response to rapid melting of sea ice stimulates metabolic activities of the denitrifying and anammox bacteria, thereby enhancing the N removal process in the ASP.

  18. [Roald Amundsen--a study of personality].

    Science.gov (United States)

    Albretsen, C S

    1996-12-10

    Roald Amundsen is the most famous of the Norwegian polar explorers. His ancestors came from a group of islands south-east of the Oslofjord. From being fishermen and sailors, they progressed to becoming captains and shipowners in the course of two generations. Amundsen's father, Jens, stayed at sea until his ship went down with all the crew. Roald was 14 years of age at the time, the youngest of four competing brothers. Jens had left the close-knit local family community before that, and bought a flat in the capital, Oslo, so that his sons could get a better education. Roald's mother wanted him to study medicine. He did as she wished for a time, but was not at all interested. When his mother died, he abruptly left the university and went to sea, which had been the tradition in his family for decades. As a young boy he was an admirer of Sir John Franklin and his explorers of the Northwest Passage. Fridtjof Nansen became his ideal. The biographies about Roald Amundsen are very diverging--some hold him a hero, others reflect a strongly critical attitude. Here, the author tries to define his personality and places him firmly within the narcissistic domain. His tendency to seek the company of married women, but to take immediate flight when they really became interested reflects an Oedipus complex from before puberty. The tragic death of his father, the sea captain, may have been a supposition; puberty can be seen as a period of coping with ambivalence towards an earlier idealized father. His genius combined ambitious goals with a sharp eye for details as regards the equipment used in his expeditions. In his travels in the Arctic and the Antartic he was driven forward by the energy of the nation. His heroic death, trying to save his earlier "enemy", Nobile, was probably caused by an urge for self-destruction.

  19. Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

    NARCIS (Netherlands)

    Thuroczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

    2012-01-01

    Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for > 70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe).

  20. Miocene Antarctic ice dynamics in the Ross Embayment (Western Ross Sea, Antarctica): Insights from provenance analyses of sedimentary clasts in the AND-2A drill core

    Science.gov (United States)

    Cornamusini, Gianluca; Talarico, Franco M.

    2016-11-01

    A detailed study of gravel-size sedimentary clasts in the ANDRILL-2A (AND-2A) drill core reveals distinct changes in provenance and allows reconstructions to be produced of the paleo ice flow in the McMurdo Sound region (Ross Sea) from the Early Miocene to the Holocene. The sedimentary clasts in AND-2A are divided into seven distinct petrofacies. A comparison of these with potential source rocks from the Transantarctic Mountains and the coastal Southern Victoria Land suggests that the majority of the sedimentary clasts were derived from formations within the Devonian-Triassic Beacon Supergroup. The siliciclastic-carbonate petrofacies are similar to the fossiliferous erratics found in the Quaternary Moraine in the southern McMurdo Sound and were probably sourced from Eocene strata that are currently hidden beneath the Ross Ice Shelf. Intraformational clasts were almost certainly reworked from diamictite and mudstone sequences that were originally deposited proximal to the drill site. The distribution of sedimentary gravel clasts in AND-2A suggests that sedimentary sequences in the drill core were deposited under two main glacial scenarios: 1) a highly dynamic ice sheet that did not extend beyond the coastal margin and produced abundant debris-rich icebergs from outlet glaciers in the central Transantarctic Mountains and South Victoria Land; 2) and an ice sheet that extended well beyond the coastal margin and periodically advanced across the Ross Embayment. Glacial scenario 1 dominated the early to mid-Miocene (between ca. 1000 and 225 mbsf in AND-2A) and scenario 2 the early Miocene (between ca. 1138 and 1000 mbsf) and late Neogene to Holocene (above ca. 225 mbsf). This study augments previous research on the clast provenance and highlights the added value that sedimentary clasts offer in terms of reconstructing past glacial conditions from Antarctic drill core records.

  1. Chickamauga reservoir embayment study - 1990

    Energy Technology Data Exchange (ETDEWEB)

    Meinert, D.L.; Butkus, S.R.; McDonough, T.A.

    1992-12-01

    The objectives of this report are three-fold: (1) assess physical, chemical, and biological conditions in the major embayments of Chickamauga Reservoir; (2) compare water quality and biological conditions of embayments with main river locations; and (3) identify any water quality concerns in the study embayments that may warrant further investigation and/or management actions. Embayments are important areas of reservoirs to be considered when assessments are made to support water quality management plans. In general, embayments, because of their smaller size (water surface areas usually less than 1000 acres), shallower morphometry (average depth usually less than 10 feet), and longer detention times (frequently a month or more), exhibit more extreme responses to pollutant loadings and changes in land use than the main river region of the reservoir. Consequently, embayments are often at greater risk of water quality impairments (e.g. nutrient enrichment, filling and siltation, excessive growths of aquatic plants, algal blooms, low dissolved oxygen concentrations, bacteriological contamination, etc.). Much of the secondary beneficial use of reservoirs occurs in embayments (viz. marinas, recreation areas, parks and beaches, residential development, etc.). Typically embayments comprise less than 20 percent of the surface area of a reservoir, but they often receive 50 percent or more of the water-oriented recreational use of the reservoir. This intensive recreational use creates a potential for adverse use impacts if poor water quality and aquatic conditions exist in an embayment.

  2. Sea-floor texture and physiographic zones of the inner continental shelf from Salisbury to Nahant, Massachusetts, including the Merrimack Embayment and Western Massachusetts Bay

    Science.gov (United States)

    Pendleton, Elizabeth E.; Barnhardt, Walter A.; Baldwin, Wayne E.; Foster, David S.; Schwab, William C.; Andrews, Brian D.; Ackerman, Seth D.

    2015-10-26

    A series of maps that describe the distribution and texture of sea-floor sediments and physiographic zones of Massachusetts State waters from Nahant to Salisbury, Massachusetts, including western Massachusetts Bay, have been produced by using high-resolution geophysical data (interferometric and multibeam swath bathymetry, lidar bathymetry, backscatter intensity, and seismic reflection profiles), sediment samples, and bottom photographs. These interpretations are intended to aid statewide efforts to inventory and manage coastal and marine resources, link with existing data interpretations, and provide information for research focused on coastal evolution and environmental change. Marine geologic mapping of the inner continental shelf of Massachusetts is a statewide cooperative effort of the U.S. Geological Survey and the Massachusetts Office of Coastal Zone Management.

  3. Evaluation of the short-term sea cliff retreat along the Tróia-Sines Embayed Coast (Costa da Galé sector), using stereo digital aerial images and Bayesian inference

    Science.gov (United States)

    Gama, C.; Jalobeanu, A.

    2011-12-01

    Monitoring the sediment budget of coastal systems is essential to understand the costal equilibrium, and is an important aspect to be considered in coastal management. Thus, the identification and the quantitative evaluation of sedimentary sources and sinks are the first steps towards a better understanding of the dynamics of coastal morphology. The Tróia-Sines Embayed Coast (TSEC) in the southwest Portuguese coast corresponds to a continuous sandy beach that extends for approximately 65 km. It is limited at north by the Sado river estuary and at south by the Sines cape. Beaches are discontinuously limited landward by dunes (≈42 km) and by sea cliffs (≈18 km) made of poorly consolidated Plio-Plistocene detrital deposits. Cliff erosion by subaerial processes or gullying is a continuous phenomenon that contributes a significant amount of sediment to the TSEC coastal system, which is what we want to measure. Mainly due to winter rainfall, sea cliffs develop debris fans at the backshore inner limit, therefore we chose to make morphological measurements at one year interval. Thus, two series digital aerial images at 20 cm resolution were acquired in Oct 2008 and July 2009, supported by a collection of ground control points (GCP) to constrain the sensor orientation. Digital aerial stereo image pairs are used as main data source to reconstruct digital surface models (DSM). A new stereo photogrammetric method is used, based on dense disparity maps and Bayesian inference (Jalobeanu et al, 2010 and Jalobeanu, 2011). The originality of this method is in the computation of the spatial distribution of elevation errors in the DSM using stochastic modelling and probabilistic inference, which helps to detect the statistically significant changes in the estimated topography. The difference between the two generated DSMs is used to characterize the variability of the main subaerial beach morphodynamics parameters, such as: i) the alongshore beach configuration; ii) the beach

  4. Poles apart: Scott, Amundsen and science.

    Science.gov (United States)

    Larson, Edward J

    2011-12-01

    One hundred years ago, teams led by Roald Amundsen and Robert Scott may have been heading in the same direction but they were poles apart in the way they sought their goals. Amundsen led a five-person team of expert Nordic skiers and dog-sledders with a single goal: getting to the South Pole first. He planned and executed the effort brilliantly. Scott, in contrast, led a complex and multi-faceted Antarctic expedition with 33 explorers and scientists, many of whom were focused on ambitious and often taxing scientific research projects that had nothing whatsoever to do with reaching the Pole. Although Scott failed to reach the South Pole first and died with four men on the return trip, his expedition made significant contributions to Antarctic science. Indeed, at least some of Scott's failure to reach the Pole first and the subsequent death of his polar party on the return trip can be attributed to burden of trying to do too much and not focusing on reaching the pole.

  5. Phytoplankton biomass and pigment responses to Fe amendments in the Pine Island and Amundsen polynyas

    Science.gov (United States)

    Mills, Matthew M.; Alderkamp, Anne-Carlijn; Thuróczy, Charles-Edouard; van Dijken, Gert L.; Laan, Patrick; de Baar, Hein J. W.; Arrigo, Kevin R.

    2012-09-01

    Nutrient addition experiments were performed during the austral summer in the Amundsen Sea (Southern Ocean) to investigate the availability of organically bound iron (Fe) to the phytoplankton communities, as well as assess their response to Fe amendment. Changes in autotrophic biomass, pigment concentration, maximum photochemical efficiency of photosystem II, and nutrient concentration were recorded in response to the addition of dissolved free Fe (DFe) and Fe bound to different model ligands. Analysis of pigment concentrations indicated that the autotrophic community was dominated by the prymnesiophyte Phaeocystis antarctica throughout most of the Amundsen Sea, although diatoms dominated in two experiments conducted in the marginal ice zone. Few significant differences in bulk community biomass (particulate organic carbon, nitrogen, and chlorophyll a) were observed, relative to the controls, in treatments with Fe added alone or bound to the ligand phytic acid. In contrast, when Fe was bound to the ligand desferrioxamine B (DFB), decreases in the bulk biomass indices were observed. The concentration of the diatom accessory pigment fucoxanthin showed little response to Fe additions, while the concentration of the P. antarctica-specific pigment, 19'-hexanoyloxyfucoxanthin (19'-hex), decreased when Fe was added alone or bound to the model ligands. Lastly, differences in the nitrate:phosphate (NO3-:PO43-) utilization ratio were observed between the Fe-amended treatments, with Fe bound to DFB resulting in the lowest NO3-:PO43- uptake ratios (˜10) and the remaining Fe treatments having higher NO3-:PO43- uptake ratios (˜17). The data are discussed with respect to glacial inputs of Fe in the Amundsen Sea and the bioavailability of Fe. We suggest that the previously observed high NO3-:PO43- utilization ratio of P. antarctica is a consequence of its production of dissolved organic matter that acts as ligands and increases the bioavailability of Fe, thereby stimulating the

  6. Geomorphology and anthropogenic impact including military constraints in a microtidal wave-dominated embayment in south western Sardinia (Porto Pino beach, SCI ITB040025, Mediterranean Sea). Implications for beach management.

    Science.gov (United States)

    De Muro, Sandro; Buosi, Carla; Pusceddu, Nicola; Frongia, Paolo; Passarella, Marinella; Ibba, Angelo

    2016-04-01

    The coastal zones of the Mediterranean have undergone increasing pressure over the last century. The intensifying coastal development and the increasing tourist impact have led to an intense transformation of the coastlines and adjacent marine areas. The beach and the coastal dune play an important role in protecting the coastline. Thus, the study of its geomorphological evolution and of its anthropic modification is fundamental in order to adopt the best management practices. In this regard, the LIFE Project (LIFE13NAT/IT/001013) SOSS DUNES (Safeguard and management Of South-western Sardinian Dunes) aims to safeguard the dune habitats and the beach system in a site belonging to the Natura 2000 network, an EUwide network of nature protection areas established under the 1992 Habitats Directive. This project is focused on a microtidal wave-dominated embayment located in south western Sardinia (Italy, Mediterranean Sea) called Porto Pino beach comprised in the SCI (Site of Community Importance) "Promontory, dunes and wetland of Porto Pino (ITB040025)". This research aims to investigate the geomorphological processes, the evolution and the main human impacts on Porto Pino beach as an useful tool for both conservation and coastal management. The coastal area of Porto Pino is represented by sandy shorelines extending for a total length of 5 km characterized by a wide primary and secondary dune systems, a backshore wetland lagoon and marsh area arranged parallel to the coastline. This littoral area can be ideally divided into three parts: the first, about 600 m long, in the north-west part characterized by the highest human pressure due to touristic activity on the foredunes and deposition of beach wrack; the second part in the south-east, about 1100 m long, characterized by a complex dune system (primary and secondary foredunes); and the third southernmost part included in a military area, about 3300 m long, characterized by transgressive dune system with low human

  7. Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

    Science.gov (United States)

    Thuróczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

    2012-09-01

    Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for >70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe). The organic complexation of dissolved Fe was investigated in the Amundsen Sea during the spring of 2009 to better understand the potential role of ligands in enhancing the local stock of dissolved Fe. The main sources of Fe and ligands to the Amundsen Sea are thought to be melting sea-ice and the Circumpolar Deep Water (CDW), which is modified (MCDW) on the continental shelf and upwells beneath the coastal glaciers and ice-shelves. Upwelling of relatively warm MCDW is also responsible for the rapid melting of the Pine Island Glacier (PIG) and surrounding ice-shelves, resulting in additional release of Fe into surface waters. At upwelling stations near ice shelves, organic ligands were nearly saturated with Fe, thus enhancing the stock of Fe and its availability to the phytoplankton community. However, ligands had little capacity to buffer additional Fe input from glacial melt. In these coastal upwelling regions, much of the glacial Fe supply is lost due to vertical export of Fe via scavenging and precipitation. Conversely, within the phytoplankton bloom in the nearby coastal polynyas, the uptake of Fe combined with the production of organic matter enhanced the abundance of relatively unsaturated organic ligands capable of stabilizing additional Fe supplied from glacial melt. These unsaturated dissolved organic ligands, combined with the continuous input of Fe (dissolved and particulate) from glacial melt, appear to favor the solubilization of Fe, thus increasing the stock of bioavailable Fe and fueling the phytoplankton bloom.

  8. Nutrient budgets for large Chinese estuaries and embayment

    Directory of Open Access Journals (Sweden)

    S. M. Liu

    2009-01-01

    Full Text Available Nutrient concentrations among the Chinese rivers and bays vary 10–75 fold depending on nutrient elements. The silicic acid levels in South China rivers are higher than those from North China rivers and the yields of dissolved silicate increased from the north to the south of China, indicating the effect of climate on weathering. The nutrient levels in Chinese rivers are higher than those from the large and less-disturbed world rivers such as Amazon and Zaire, but comparable to the values for European and North American polluted and eutrophic rivers like the Loire and Po. This may be ascribed to both of extensive leaching and influences from agricultural and domestic activities over the drainage basins of Chinese rivers. DIN:PO3−4 ratios in most of Chinese rivers and bays are higher (up to 2800 than the other rivers in the world. The atomic ratios of DIN to PO43− in the major Chinese rivers and embayment decrease in exponential trend with increase in the atomic ratios of PO43− to Si(OH4, indicating that primary production in coastal environments changes with the nutrients transport when the urbanization develops to a certain extent, and the potential limited nutrient elements can be changed from phosphorus to nitrogen limitation, which can modify aquatic food webs and then the ocean ecosystem.

    A simple steady-state mass-balance box model was employed. The output shows that the estuaries and embayment behave as a sink or source of nutrients. For the major Chinese estuaries, both residual and mixing flow transport nutrients off the estuaries, and nutrient transport fluxes in summer is 3–4 fold that in winter except comparable for NH4+. These fluxes are 1.0–1.7 fold that estimated by timing riverine nutrient concentrations and freshwater discharge. For the major Chinese embayment, nutrient elements are transported to China Seas

  9. Mineralogical, geochemical, and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic)

    Science.gov (United States)

    Gamboa, Adriana; Montero-Serrano, Jean-Carlos; St-Onge, Guillaume; Rochon, André; Desiage, Pierre-Arnaud

    2017-02-01

    Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr, Zn) indicate that modern sedimentary deposition within the Mackenzie-Beaufort Sea Slope and Amundsen Gulf took place under oxic bottom-water conditions, with more turbulent mixing conditions and thus a well-oxygenated water column prevailing within the Amundsen Gulf. The analytical data obtained, combined with multivariate statistical (notably, principal component and fuzzy c-means clustering analyses) and spatial analyses, allowed the division of the study area into four provinces with distinct sedimentary compositions: (1) the Mackenzie Trough-Canadian Beaufort Shelf with high phyllosilicate-Fe oxide-magnetite and Al-K-Ti-Fe-Cr-V-Zn-P contents; (2) Southwestern Banks Island, characterized by high dolomite-K-feldspar and Ca-Mg-LOI contents; (3) the Central Amundsen Gulf, a transitional zone typified by intermediate phyllosilicate-magnetite-K-feldspar-dolomite and Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-LOI contents; and (4) mud volcanoes on the Canadian Beaufort Shelf distinguished by poorly sorted coarse-silt with high quartz-plagioclase-authigenic carbonate and Si-Zr contents, as well as high magnetic susceptibility. Our results also confirm that the present-day sedimentary dynamics on the Canadian Beaufort Shelf is mainly controlled by sediment supply from the Mackenzie River. Overall, these insights provide a basis for future studies using mineralogical, geochemical, and magnetic signatures of Canadian Arctic sediments in order to reconstruct past variations in sediment inputs and transport pathways related to late Quaternary climate and oceanographic changes.

  10. Late Wisconsin and early holocene glacial history, inner Ross Embayment, Antarctica

    Science.gov (United States)

    Denton, George H.; Bockheim, James G.; Wilson, Scott C.; Stuiver, Minze

    1991-01-01

    Lateral drift sheets of outlet glaciers that pass through the Transantarctic Mountains constrain past changes of the huge Ross ice drainage system of the Antarctic Ice Sheet. Drift stratigraphy suggests correlation of Reedy III (Reedy Glacier), Beardmore, Britannia (Hatherton/Darwin Glaciers), Ross Sea (McMurdo Sound), and younger (Terra Nova Bay) drifts; radiocarbon dates place the outer limits of Ross Sea drift in late Wisconsin time at 24,000 to 13,000 yr B.P. Outlet glacier profiles from these drifts constrain late Wisconsin ice sheet surface elevations. Within these constraint, two extreme late Wisconsin reconstructions are given of the Ross ice drainage system. Both show little elevation change of the polar plateau coincident with extensive ice shelf grounding along the inner Ross Embayment. However, in the central Ross Embayment, one reconstruction shows floating shelf ice, where as the other shows a grounded ice sheet. Massive late Wisconsin/Holocene recession of grounded ice from the western Ross Embayment, which was underway at 13,040 yr B.P. and completed by 6600 to 6020 yr B.P., was accompanied by little change in plateau ice levels inland of the Transantarctic Mountains.

  11. Micropaleontologic record of Quaternary paleoenvironments in the Central Albemarle Embayment, North Carolina, U.S.A.

    Science.gov (United States)

    Culver, Stephen J.; Farrell, Kathleen M.; Mallinson, David J.; Willard, Debra A.; Horton, Benjamin P.; Riggs, Stanley R.; Thieler, E. Robert; Wehmiller, John F.; Parham, Peter; Snyder, Scott W.; Hillier, Caroline

    2011-01-01

    To understand the temporal and spatial variation of eustatic sea-level fluctuations, glacio-hydro-isostacy, tectonics, subsidence, geologic environments and sedimentation patterns for the Quaternary of a passive continental margin, a nearly complete stratigraphic record that is fully integrated with a three dimensional chronostratigraphic framework, and paleoenvironmental information are necessary. The Albemarle Embayment, a Cenozoic regional depositional basin in eastern North Carolina located on the southeast Atlantic coast of the USA, is an ideal setting to unravel these dynamic, interrelated processes.Micropaleontological data, coupled with sedimentologic, chronostratigraphic and seismic data provide the bases for detailed interpretations of paleoenvironmental evolution and paleoclimates in the 90. m thick Quaternary record of the Albemarle Embayment. The data presented here come from a transect of cores drilled through a barrier island complex in the central Albemarle Embayment. This area sits in a ramp-like setting between late Pleistocene incised valleys.The data document the episodic infilling of the Albemarle Embayment throughout the Quaternary as a series of transgressive-regressive (T-R) cycles, characterized by inner shelf, midshelf, and shoreface assemblages, that overlie remnants of fluvial to estuarine valley-fill. Barrier island and marginal marine deposits have a low preservation potential. Inner to mid-shelf deposits of the early Pleistocene are overlain by similar middle Pleistocene shelf sediments in the south of the study area but entirely by inner shelf deposits in the north. Late Pleistocene marine sediments are of inner shelf origin and Holocene deposits are marginal marine in nature. Pleistocene marine sediments are incised, particularly in the northern half of the embayment by lowstand paleovalleys, partly filled by fluvial/floodplain deposits and in some cases, overlain by remnants of transgressive estuarine sediments. The shallowing

  12. Confluence and redistribution of Atlantic water in the Nansen, Amundsen and Makarov basins

    Directory of Open Access Journals (Sweden)

    U. Schauer

    Full Text Available The waters in the Eurasian Basin are conditioned by the confluence of the boundary flow of warm, saline Fram Strait water and cold low salinity water from the Barents Sea entering through the St. Anna Trough. Hydrographic sections obtained from RV Polarstern during the summer of 1996 (ACSYS 96 across the St. Anna Trough and the Voronin Trough in the northern Kara Sea and across the Nansen, Amundsen and Makarov basins allow for the determination of the water mass properties of the two components and the construction of a qualitative picture of the circulation both within the Eurasian Basin and towards the Canadian Basin. At the confluence north of the Kara Sea, the Fram Strait branch is displaced from the upper to the lower slope and it forms a sharp front to the Barents Sea water at depths between 100 m and greater than 1000 m. This front disintegrates downstream along the basin margin and the two components are largely mixed before the boundary current reaches the Lomonosov Ridge. Away from the continental slope, the presence of interleaving structures coherent over wide distances is consistent with low lateral shear. The return flow along the Nansen Gakkel Ridge, if present at all, seems to be slow and the cold water below a deep mixed layer there indicates that the Fram Strait Atlantic water was not covered with a halocline for about a decade. Anomalous water mass properties in the interior of the Eurasian Basin can be attributed to isolated lenses rather than to baroclinic flow cores. Eddies have probably detached from the front at the confluence and migrated into the interior of the basin. One deep (2500 m lens of Canadian Basin water, with an anticyclonic eddy signature, must have spilled through a gap of the Lomonosov Ridge. During ACSYS 96, no clear fronts between Eurasian and Canadian intermediate waters, such as those observed further north in 1991 and 1994, were found at the Siberian side of the Lomonosov Ridge. This indicates that

  13. Neritic sediments of the Merrimack Embayment (ANAN71 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The coastal dunes, beaches, and inner neritic zone of the Merrimack Embayment constitute a petrologic province. In addition to heavy mineral analyses, grain size...

  14. Coastal evolution between two giant rivers: The Chan May embayment in central Vietnam

    Science.gov (United States)

    Gouramanis, C.; Switzer, A.; Bristow, C.; Pham, D. T.; Mauz, B.; Pile, J.; Doan, L. D.; Hoang, Q. D.; Ngo, C. K.; Dao, N.; Polivka, P.; Soria, L.; Lee, Y.; Sloss, C.; Hoang, L. V.

    2015-12-01

    The coastal landscapes of Vietnam are dominated in the north and south by the very large Red and Mekong rivers. Central Vietnam, in contrast, has few large rivers that flow to the coastal zone. This coupled with the high relief (>1500 m) of the granitic Truong Son Range and shallow gradient continental shelf, has produced two different coastal geomorphologies. The first is a shallow basin infilled with a sequence of parallel, arcuate beach ridges, and the second includes the development of shore-parallel spits and coastal lagoons. All systems are Holocene in age and we present evidence of the Holocene evolution of the northward-facing, beach ridge strandplain located in the Chan May embayment, approximately 35 km north of Danang. This embayment is relatively small (5 km long at the beach and with a beach ridge sequence that spans 11 km from the modern beach to the base of the Truong Son Range) compared to other beach ridge strandplains to the north and south and serves as an analogue for the evolution of these larger systems. The Holocene evolution of the embayment was resolved using Ground Penetrating Radar (GPR), high-resolution sedimentological analysis and quartz Optically Stimulated Luminescence were used to investigate the internal stratigraphy and chronological development of the beach ridges at Chan May. The strandplain contains uniform, clean quartz-rich sediment interspersed by thin heavy mineral rich bands forming shallow-gradient beach ridges that have steadily prograded seaward during the regression after the mid-Holocene sea level highstand. As the beach ridges prograded seaward, a small river feeding directly from the Truong Son Range meandered across the strandplain and significantly modified the embayment. Recently, the river has become much reduced due to anthropogenic modification of the river and landscape. Prior to the Holocene marine highstand, the area was similarly characterized by a surface of prograding beach ridges that were eroded by

  15. Groundwater availability of the Mississippi embayment

    Science.gov (United States)

    Clark, Brian R.; Hart, Rheannon M.; Gurdak, Jason J.

    2011-01-01

    Groundwater is an important resource for agricultural and municipal uses in the Mississippi embayment. Arkansas ranks first in the Nation for rice and third for cotton production, with both crops dependent on groundwater as a major source of irrigation requirements. Multiple municipalities rely on the groundwater resources to provide water for industrial and public use, which includes the city of Memphis, Tennessee. The demand for the groundwater resource has resulted in groundwater availability issues in the Mississippi embayment including: (1) declining groundwater levels of 50 feet or more in the Mississippi River Valley alluvial aquifer in parts of eastern Arkansas from agricultural pumping, (2) declining groundwater levels of over 360 feet over the last 90 years in the confined middle Claiborne aquifer in southern Arkansas and northern Louisiana from municipal pumping, and (3) litigation between the State of Mississippi and a Memphis water utility over water rights in the middle Claiborne aquifer. To provide information to stakeholders addressing the groundwater-availability issues, the U.S. Geological Survey Groundwater Resources Program supported a detailed assessment of groundwater availability through the Mississippi Embayment Regional Aquifer Study (MERAS). This assessment included (1) an evaluation of how these resources have changed over time through the use of groundwater budgets, (2) development of a numerical modeling tool to assess system responses to stresses from future human uses and climate trends, and (3) application of statistical tools to evaluate the importance of individual observations within a groundwater-monitoring network. An estimated 12 million acre-feet per year (11 billion gallons per day) of groundwater was pumped in 2005 from aquifers in the Mississippi embayment. Irrigation constitutes the largest groundwater use, accounting for approximately 10 million acre-feet per year (9 billion gallons per day) in 2000 from the Mississippi

  16. Helmer Hanssens reiser i isbaksen. Med Roald Amundsen og polene som omdreiningspunkt

    Directory of Open Access Journals (Sweden)

    Lena Arekol

    2014-08-01

    Full Text Available Helmer Hanssen published his book Gjennem isbaksen. Atten år med Roald Amundsen in 1941. Five years earlier, in 1936, this book had been published in English with the title Voyages of a modern Viking. The Norwegian title of the book may be understood as a reflection of his polar life and almost lifelong relation to Amundsen; while the English title indicates more that Hanssen wanted to emphasis his own solid achievements in the Polar Regions. In earlier history studies Hanssen has been interpreted merely as the loyal assistant of Amundsen and as an eternal deuce. This article represents a new reading of Hanssen’s book up against previously known and unknown sources. This brings on new perspectives on the relation between Hanssen and Amundsen, but also on Hanssen himself, his relationship to his family, his perceptions of the Inuit people and his strong desire to go on a polar expedition. In this article, I argue that being the eternal deuce that is what, was Hanssen’s big chance. Amundsen gave him the possibility to experience pioneering expeditions and to see the world. My point is that Hanssen, even when living in the shadow of Amundsen, had his place in the outer circle of the spotlight.

  17. Mechanical effect of mélange-induced buttressing on embayment-terminating glacier dynamics

    Directory of Open Access Journals (Sweden)

    D. Seneca Lindsey

    2012-09-01

    Full Text Available Embayment terminating glaciers interact dynamically with seasonal sea ice and icebergs, a mixture we refer to as mélange. For certain glaciers, mélange prevents calved bergs from rotating away from the front, thus allowing the ice front to advance into the embayment. Here we demonstrate that mélange can, if rigid enough, provide sufficient buttressing to reduce the calving rate, while leaving the ice-front velocity largely unaffected. The net result is additional ice-front advance.

    Observations indicate a seasonal advance/retreat cycle has occurred at Jakobshavn Isbræ since the 1950s. We model an idealized Jakobshavn Isbræ-like scenario and find that mélange may be responsible for a seasonal ice-front advance of up to 0.6 km. These results come from a model that incorporates mélange into the interior of the domain, includes relevant stresses, and models drag via a kinematic boundary condition. A weakening or loss of mélange due to increasing temperatures would lead to further mass loss from glaciers such as Jakobshavn Isbræ.

  18. Sedimentary infilling of bedrock-controlled palaeo-embayments off Cape Trafalgar, Strait of Gibraltar (Gulf of Cadiz)

    Science.gov (United States)

    de Castro, Sandra; Lobo, Francisco J.

    2017-05-01

    This study investigates two bedrock-controlled palaeo-coastal embayments on the Barbate Platform off Cape Trafalgar near the Strait of Gibraltar (Gulf of Cadiz shelf, SW Iberian Peninsula), aiming to reveal their infilling dynamics and the influence of rocky outcrops on shallow-water hydrodynamics and sediment transport. The approach relies on detailed multibeam bathymetric data, high-resolution seismic profiles and tidal current simulations. Elongated rocky outcrops formed a palaeo-coast when sea level was approximately 35 to 20 m below that of the present day, and bound a relatively flat area. However, the seismic profiles enabled to distinguish two main troughs (A and B) that were infilled following a distinctive evolution during the last transgression. Five seismic units were identified (I to V, from base to top). Deposit A is composed of seismic units II to V and is interpreted as a marine embayment infill, here termed the Barbate palaeo-embayment (BPE). Deposit B is composed of seismic units I to IV and is interpreted as a palaeo-valley infill, here termed the Barbate palaeo-valley (BPV). The complex internal stratigraphic architecture depicts an overall evolution from tidal/fluvial deposits to shallow-water marine deposits. Most significant is the occurrence of coupled tidal flats/estuarine sand bars constituting the infilling of the BPE; this suggests the persistence of a high-energy current in a shallow, confined embayment, which was amplified by the rocky outcrop constrictions and possibly facilitated by the episodic movement of a normal fault. In contrast to this active setting, the nearby straight and narrow BPV was subjected to lower-energy infilling dynamics during its initial flooding phases. There, tidal activity was possibly reduced by the straight morphology of the valley and the occurrence of a topographic constriction (i.e. the Barbate Passage) at the mouth of the valley.

  19. SOLUTION MINING IN SALT DOMES OF THE GULF COAST EMBAYMENT

    Energy Technology Data Exchange (ETDEWEB)

    Griswold, G. B.

    1981-02-01

    Following a description of salt resources in the salt domes of the gulf coast embayment, mining, particularly solution mining, is described. A scenario is constructed which could lead to release of radioactive waste stored in a salt dome via inadvertent solution mining and the consequences of this scenario are analyzed.

  20. Observations of shoreline-sandbar coupling on an embayed beach

    NARCIS (Netherlands)

    van de Lageweg, W.I.; Bryan, K.R.; Coco, G.; Ruessink, B.G.

    2013-01-01

    We analyse a seven-year dataset (1999–2005) of shoreline and sandbar variations derived from video observations at the embayed Tairua Beach, New Zealand, to explore sandbar–shoreline coupling and to determine how this coupling is related to alongshore-averaged sandbar–shoreline separation and beach

  1. Two-dimensional water quality modeling of Town Creek embayment on Guntersville Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Bender, M.D.; Shiao, Ming C.; Hauser, G.E. (Tennessee Valley Authority, Norris, TN (USA). Engineering Lab.); Butkus, S.R. (Tennessee Valley Authority, Norris, TN (USA). Water Quality Dept.)

    1990-09-01

    TVA investigated water quality of Town Creek embayment using a branched two-dimensional model of Guntersville Reservoir. Simulation results were compared in terms of algal biomass, nutrient concentrations, and volume of embayment with depleted dissolved oxygen. Stratification and flushing play a significant role in the embayment water quality. Storms introduce large loadings of organics, nutrients, and suspended solids. Dissolved oxygen depletion is most severe after storms followed by low flow that fails to flush the embayment. Embayment water quality responses to potential animal waste and erosion controls were explored. Modeling indicated animal waste controls were much more cost-effective than erosion controls. Erosion controls will decrease embayment suspended solids and thereby increase algal biomass due to greater light penetration. 29 refs., 16 figs., 4 tabs.

  2. Reorganization of Strain in Response to Erosional Forcing at Intermediate Scales: Puli Embayment, Western Taiwan

    Science.gov (United States)

    Upton, P.; Mueller, K. J.; Koons, P. O.; Powell, L.

    2003-12-01

    The Taiwan orogeny accommodates 82 mm of oblique convergence per year between the Philippine Sea and Eurasian plates and is situated in a region of very high rainfall, resulting in high rates of rock uplift and erosion. Studies in western Taiwan suggest that there is considerable along strike variation in late Quaternary erosion rates and in the modern distribution of strain along the western margin of the orogen. In the Puli Embayment, a 50 km wide, 1500 m deep depression within the Foothills belt, Hsueshan Range and Backbone Ranges of western Taiwan, lower elevation and enhanced exhumation are associated with a broad 50 km wide belt of active shortening hindward of the leading edge of the orogen. Localized high erosion rates have been shown to significantly influence the mechanical behavior of collisional mountain belts on timescales of 1-5 Ma where the wavelength of the erosional signal is on the order of the thickness of the brittle crust. Examples include the Southern Alps of New Zealand and the indentor corners, Nanga Parbat and Namche Bawa, of the Himalaya, where the geometry of the erosional signal is reflected in the topographic and petrological signal of the resultant mountain belt. The coincidence of enhanced exhumation, lower elevation and active deformation suggests that the Puli embayment is accommodating shortening and rock uplift in response to the reduction in mass. If so, it is occurring on shorter temporal and spatial scales than previously documented and may represent the early stages of river-induced thermal thinning leading to the formation of a structure on the scale of an anticlinorium. Western Taiwan provides an ideal setting in which to explore, on a sub-orogen scale, the implications of enhanced exhumation for the beginnings of reorganization of strain within an orogen at higher spatial and temporal frequency.

  3. Darwin's Navidad embayment, Santiago region, Chile, as a model of the southeastern Pacific shelf

    Energy Technology Data Exchange (ETDEWEB)

    Cecioni, G.

    1980-01-01

    The sedimentary sequence of Darwin's Navidad embayment overlies a Carboniferous metamorphic basement, and was deposited in a NNW-striking basin, open toward the sea. The sediments formed in a temperate climate and consist of three marine sequences-Cretaceous, Eocene, and Miocene-Pliocene. They exhibit some potential for oil and gas. The uppermost sediments of the Navidad Group were deposited in a more extensive sea, which was deeper, with lower wave energy. Near the present Pacific coastline, the sediments are tectonically disturbed. Farther east-and northward, the sediments are not affected by great disturbances. Some good types of stratigraphical traps, such as eolian sand beaches, may be expected. 3 figures.

  4. Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

    Science.gov (United States)

    Comiso, Josefino; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

    2011-01-01

    Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

  5. Seismic Noise Characterization in the Northern Mississippi Embayment

    Science.gov (United States)

    Wiley, S.; Deshon, H. R.; Boyd, O. S.

    2009-12-01

    We present a study of seismic noise sources present within the northern Mississippi embayment near the New Madrid Seismic Zone (NMSZ). The northern embayment contains up to 1 km of unconsolidated coastal plain sediments overlying bedrock, making it an inherently noisy environment for seismic stations. The area is known to display high levels of cultural noise caused by agricultural activity, passing cars, trains, etc. We characterize continuous broadband seismic noise data recorded for the months of March through June 2009 at six stations operated by the Cooperative New Madrid Seismic Network. We looked at a single horizontal component of data during nighttime hours, defined as 6:15PM to 5:45AM Central Standard Time, which we determined to be the lowest amplitude period of noise for the region. Hourly median amplitudes were compared to daily average wind speeds downloaded from the National Oceanic and Atmospheric Administration. We find a correlation between time periods of increased noise and days with high wind speeds, suggesting that wind is likely a prevalent source of seismic noise in the area. The effects of wind on seismic recordings may result from wind induced tree root movement which causes ground motion to be recorded at the vaults located ~3m below ground. Automated studies utilizing the local network or the EarthScope Transportable Array, scheduled to arrive in the area in 2010-11, should expect to encounter wind induced noise fluctuations and must account for this in their analysis.

  6. Assessing the extreme overwash regime along an embayed urban beach

    Science.gov (United States)

    Silveira, Tanya M.; Taborda, Rui; Carapuço, Mafalda M.; Andrade, César; Freitas, Maria C.; Duarte, João F.; Psuty, Norbert P.

    2016-12-01

    Coastal overwash is one of the most important hazards affecting the coastal zone and therefore has been the focus of several studies related to the establishment of setback lines. However, studies of extreme overwash (EO) events along urban beaches backed by a seawall or structure are scarce, and reveal the difficulties associated with its assessment, measurement and validation. The Nazaré coastal urban area (located on the west coast of Portugal) is developed adjacent to an embayed reflective beach and is subject to frequent and localized inundation due to EO events capable of overtopping the protection seawall. The current work develops a methodological approach to simulate total water levels (TWL) and seawall overtopping occurrences in time and space, with the ultimate goal of identifying the factors that govern the extreme overwash regime. The method uses multi-decadal time series of site-specific wave and tide, and high-resolution topo-bathymetric data, and recreates the TWL time series for a 36-year period. The model is successfully validated against video imagery and maximum swash line data that provide information on the reach of the water levels measured during modal and extreme TWL conditions along the studied beach. This study establishes the importance of the interaction of the modal and extreme hydrodynamic processes with the beach and backshore morphology. The Nazaré embayment is in equilibrium with the alongshore-varying modal wave conditions, resulting in higher vulnerability of the most sheltered sector during extreme events.

  7. Modes of embayed beach dynamics: analysis reveals emergent timescales

    Science.gov (United States)

    Murray, K. T.; Murray, A.; Limber, P. W.; Ells, K. D.

    2013-12-01

    Embayed beaches, or beaches positioned between rocky headlands, exhibit morphologic changes over many length and time scales. Beach sediment is transported as a result of the day-to-day wave forcing, causing patterns of erosion and accretion. We use the Rocky Coastline Evolution Model (RCEM) to investigate how patterns of shoreline change depend on wave climate (the distribution of wave-approach angles) and beach characteristics. Measuring changes in beach width through time allows us to track the evolution of the shape of the beach and the movement of sand within it. By using Principle Component Analysis (PCA), these changes can be categorized into modes, where the first few modes explain the majority of the variation in the time series. We analyze these modes and how they vary as a function of wave climate and headland/bay aspect ratio. In the purposefully simple RCEM, sediment transport is wave-driven and affected by wave shadowing behind the headlands. The rock elements in our model experiments (including the headlands) are fixed and unerodable so that this analysis can focus purely on sand dynamics between the headlands, without a sand contribution from the headlands or cliffs behind the beach. The wave climate is characterized by dictating the percentage of offshore waves arriving from the left and the percentage of waves arriving from high angles (very oblique to the coastline orientation). A high-angle dominated wave climate tends to amplify coastline perturbations, whereas a lower-angle wave climate is diffusive. By changing the headland/bay aspect ratio and wave climate, we can perform PCA analysis of generalized embayed beaches with differing anatomy and wave climate forcings. Previous work using PCA analysis of embayed beaches focused on specific locations and shorter timescales (beach dynamics over longer timescales. The first two PCA modes, which explain a majority of the beach width time series variation (typically >70%), are a 'breathing' mode and a

  8. Impact of the El Nino on the Variability of the Antarctic Sea Ice Extent

    Institute of Scientific and Technical Information of China (English)

    陈锦年; 褚健婷; 徐兰英

    2004-01-01

    In this paper, the spreading way in the southern hemisphere that anomalous warm water piled in tropical eastern Pacific is analysed and then impact of El Nino on the variability of the Antarctic sea ice extent is investigated by using a dataset from 1970 to 2002. The analysis result show that in El Nino event the anomalous warm water piled in tropical eastern Pacific is poleward propagation yet the westward propagation along southern equator current hasn 't been discovered . The poleward propagation time of the anomalous warm water is about 1 year or so. El Nino event has a close relationship with the sea ice extent in the Amundsen sea , Bellingshausen sea and Antarctic peninsula. After El Nino appears , there is a lag of two years that the sea ice in the Amundsen sea , Bellingshausea sea, especially in the Antarctic peninsula decreases obviously. The processes that El Nino has influence with Antarctic sea ice extent is the warm water piled in tropical eastern Pacific poleward propagation along off the coast of southern America and cause the anomalous temperature raise in near pole and then lead the sea ice in Amundsen sea , Bellingshausen sea and Antarctic peninsula to decrease where the obvious decrease of the sea ice since 80 'decade has close relation to the frequently appearance of El Nino.

  9. Nearshore hydrodynamics as loading and forcing factors for Escherichia coli contamination at an embayed beach

    Science.gov (United States)

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.; Byappanahalli, Muruleedhara N.

    2012-01-01

    Numerical simulations of the transport and fate of Escherichia coli were conducted at Chicago's 63rd Street Beach, an embayed beach that had the highest mean E. coli concentration among 23 similar Lake Michigan beaches during summer months of 2000-2005, in order to find the cause for the high bacterial contamination. The numerical model was based on the transport of E. coli by current circulation patterns in the embayment driven by longshore main currents and the loss of E. coli in the water column, taking settling as well as bacterial dark- and solar-related decay into account. Two E. coli loading scenarios were considered: one from the open boundary north of the embayment and the other from the shallow water near the beachfront. Simulations showed that the embayed beach behaves as a sink for E. coli in that it generally receives E. coli more efficiently than it releases them. This is a result of the significantly different hydrodynamic forcing factors between the inside of the embayment and the main coastal flow outside. The settled E. coli inside the embayment can be a potential source of contamination during subsequent sediment resuspension events, suggesting that deposition-resuspension cycles of E. coli have resulted in excessive bacterial contamination of beach water. A further hypothetical case with a breakwater shortened to half its original length, which was anticipated to enhance the current circulation in the embayment, showed a reduction in E. coli concentrations of nearly 20%.

  10. Chronology and dynamics of the Amundsen Gulf Ice Stream in Arctic Canada during the last glacial-interglacial transition

    Science.gov (United States)

    Lakeman, T. R.; MacLean, B.; Blasco, S.; Bennett, R.; Hughes Clarke, J. E.

    2012-04-01

    An extensive ice stream of the Laurentide ice sheet occupied Amundsen Gulf during the Last Glacial Maximum. The grounded ice stream extended northwestward to the margin of the inner shelf in the Beaufort Sea and to a depth of 450 metres. This glacier was one of the largest ice streams to emanate into the Arctic Ocean during the last glaciation and, as such, exerted a primary influence on the dynamics of the northwest Laurentide Ice Sheet. Ice stream retreat from its maximum position began prior to 13,000 cal yr BP. The pattern of extensive sole marks or glacial flutings on the seabed and on the adjacent mainland and islands confirms the direction of flow was from southeast to northwest. In the Gulf these features are imprinted primarily on subglacial sediment deposits. The bathymetry of the Gulf and known extent of the ice stream on land indicates the ice was at least 700 m thick. A series of moraines at the mouth of the Gulf mark temporary positions of the retreating ice stream margin. Early stages of ice retreat may have been associated with meltwater discharge under the ice stream as evidenced by current erosion associated with some sole marks or glacial flutings. Melting at the leading edge of the ice stream resulted in calving of icebergs and the generation of keel-scour marks in the seabed. Retreat of the ice stream was relatively rapid as indicated by thin and spatially discontinuous deglacial glaciomarine sediment in the Gulf. Furthermore, an expansive database of deglacial radiocarbon ages from eastern Banks Island, western Victoria Island, and the adjacent Arctic mainland, indicates that the ice stream had retreated fully from the Gulf by 12,500 cal yr BP. The lack of Holocene sediment draping the sole marks or flutings, and outcrops of exposed bedrock and glaciomarine sediment indicate very low sedimentation rates since ice retreat. The thin veneer of recent fine sediment that has been deposited discontinuously on the seabed in the Gulf indicates little

  11. Salt wedge dynamics lead to enhanced sediment trapping within side embayments in high-energy estuaries

    Science.gov (United States)

    Yellen, Brian; Woodruff, Jonathan D.; Ralston, David K.; MacDonald, D. G.; Jones, D. S.

    2017-03-01

    Off-river coves and embayments provide accommodation space for sediment accumulation, particularly for sandy estuaries where high energy in the main channel prevents significant long-term storage of fine-grained material. Seasonal sediment inputs to Hamburg Cove in the Connecticut River estuary (USA) were monitored to understand the timing and mechanisms for sediment storage there. Unlike in freshwater tidal coves, sediment was primarily trapped here during periods of low discharge, when the salinity intrusion extended upriver to the cove entrance. During periods of low discharge and high sediment accumulation, deposited sediment displayed geochemical signatures consistent with a marine source. Numerical simulations reveal that low discharge conditions provide several important characteristics that maximize sediment trapping. First, these conditions allow the estuarine turbidity maximum (ETM) to be located in the vicinity of the cove entrance, which increases sediment concentrations during flood tide. Second, the saltier water in the main channel can enter the cove as a density current, enhancing near-bed velocities and resuspending sediment, providing an efficient delivery mechanism. Finally, higher salinity water accumulates in the deep basin of the cove, creating a stratified region that becomes decoupled from ebb currents, promoting retention of sediment in the cove. This process of estuarine-enhanced sediment accumulation in off-river coves will likely extend upriver during future sea level rise.

  12. Loss of native rocky reef biodiversity in Australian metropolitan embayments.

    Science.gov (United States)

    Stuart-Smith, Rick D; Edgar, Graham J; Stuart-Smith, Jemina F; Barrett, Neville S; Fowles, Amelia E; Hill, Nicole A; Cooper, Antonia T; Myers, Andrew P; Oh, Elizabeth S; Pocklington, Jacqui B; Thomson, Russell J

    2015-06-15

    Urbanisation of the coastal zone represents a key threat to marine biodiversity, including rocky reef communities which often possess disproportionate ecological, recreational and commercial importance. The nature and magnitude of local urban impacts on reef biodiversity near three Australian capital cities were quantified using visual census methods. The most impacted reefs in urbanised embayments were consistently characterised by smaller, faster growing species, reduced fish biomass and richness, and reduced mobile invertebrate abundance and richness. Reef faunal distribution varied significantly with heavy metals, local population density, and proximity to city ports, while native fish and invertebrate communities were most depauperate in locations where invasive species were abundant. Our study adds impetus for improved urban planning and pollution management practises, while also highlighting the potential for skilled volunteers to improve the tracking of changes in marine biodiversity values and the effectiveness of management intervention.

  13. Explosion source strong ground motions in the Mississippi embayment

    Science.gov (United States)

    Langston, C.A.; Bodin, P.; Powell, C.; Withers, M.; Horton, S.; Mooney, W.

    2006-01-01

    Two strong-motion arrays were deployed for the October 2002 Embayment Seismic Excitation Experiment to study the spatial variation of strong ground motions in the deep, unconsolidated sediments of the Mississippi embayment because there are no comparable strong-motion data from natural earthquakes in the area. Each linear array consisted of eight three-component K2 accelerographs spaced 15 m apart situated 1.2 and 2.5 kin from 2268-kg and 1134-kg borehole explosion sources, respectively. The array data show distinct body-wave and surface-wave arrivals that propagate within the thick, unconsolidated sedimentary column, the high-velocity basement rocks, and small-scale structure near the surface. Time-domain coherence of body-wave and surface-wave arrivals is computed for acceleration, velocity, and displacement time windows. Coherence is high for relatively low-frequency verticalcomponent Rayleigh waves and high-frequency P waves propagating across the array. Prominent high-frequency PS conversions seen on radial components, a proxy for the direct S wave from earthquake sources, lose coherence quickly over the 105-m length of the array. Transverse component signals are least coherent for any ground motion and appear to be highly scattered. Horizontal phase velocity is computed by using the ratio of particle velocity to estimates of the strain based on a plane-wave-propagation model. The resulting time-dependent phase-velocity map is a useful way to infer the propagation mechanisms of individual seismic phases and time windows of three-component waveforms. Displacement gradient analysis is a complementary technique for processing general spatial-array data to obtain horizontal slowness information.

  14. Exhumation history along the eastern Amundsen Sea coast, West Antarctica, revealed by low-temperature thermochronology

    Science.gov (United States)

    Lindow, Julia; Kamp, Peter J. J.; Mukasa, Samuel B.; Kleber, Michel; Lisker, Frank; Gohl, Karsten; Kuhn, Gerhard; Spiegel, Cornelia

    2016-10-01

    West Antarctica experienced a complex tectonic history, which is still poorly documented, in part due to extensive ice cover. Here we reconstruct the Cretaceous to present thermotectonic history of Pine Island Bay area and its adjacent coasts, based on a combination of apatite and zircon fission track and apatite (U-Th-Sm)/He thermochronology. In addition, we report petrographic information for the catchments of Pine Island, Thurston Island, and Thwaites glaciers. Our data suggest that the underlying bedrock of the Pine Island and Thwaites Glacier catchments are very different and vary from granitoids to (Cenozoic?) volcanogenic sequences and low-grade metamorphics. Our thermochronology data show that the upper crustal rocks of Pine Island Bay experienced very rapid cooling during the late Cretaceous. We attribute this rapid cooling of basement rocks and associated reduction in mean elevation to tectonic denudation driven by gravitational collapse of the Cretaceous orogen along the proto-Pacific Gondwana margin. Rapid Cretaceous crustal cooling was followed by very slow cooling during the Cenozoic, with no erosional response—within the limits of thermochronological methods—to the onset of glaciation and subsequent climatic changes. Cenozoic rifting within the West Antarctic Rift appears to have had little effect on erosion processes around Pine Island Bay; instead, our data suggest Cenozoic crustal tilting toward Pine Island Trough, a major geomorphic feature previously suggested to be a branch of the rift system.

  15. Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker Amundsen from the Polar 6 aircraft platform

    Science.gov (United States)

    Aliabadi, Amir A.; Thomas, Jennie L.; Herber, Andreas B.; Staebler, Ralf M.; Leaitch, W. Richard; Schulz, Hannes; Law, Kathy S.; Marelle, Louis; Burkart, Julia; Willis, Megan D.; Bozem, Heiko; Hoor, Peter M.; Köllner, Franziska; Schneider, Johannes; Levasseur, Maurice; Abbatt, Jonathan P. D.

    2016-06-01

    Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior

  16. Roald Amundsen's contributions to our knowledge of the magnetic fields of the Earth and the Sun

    Directory of Open Access Journals (Sweden)

    A. Egeland

    2011-12-01

    Full Text Available Roald Amundsen (1872–1928 was known as one of the premier polar explorers in the golden age of polar exploration. His accomplishments clearly document that he has contributed to knowledge in fields as diverse as ethnography, meteorology and geophysics. In this paper we will concentrate on his studies of the Earth's magnetic field. With his unique observations at the polar station Gjøahavn (geographic coordinates 68°37'10'' N; 95°53'25'' W, Amundsen was first to demonstrate, without doubt, that the north magnetic dip-pole does not have a permanent location, but steadily moves its position in a regular manner. In addition, his carefully calibrated measurements at high latitudes were the first and only observations of the Earth's magnetic field in the polar regions for decades until modern polar observatories were established. After a short review of earlier measurements of the geomagnetic field, we tabulate the facts regarding his measurements at the observatories and the eight field stations associated with the Gjøa expedition. The quality of his magnetic observations may be seen to be equal to that of the late 20th century observations by subjecting them to analytical techniques showing the newly discovered relationship between the diurnal variation of high latitude magnetic observations and the direction of the horizontal component of the interplanetary magnetic field (IMF By. Indeed, the observations at Gjøahavn offer a glimpse of the character of the solar wind 50 yr before it was known to exist. Our motivation for this paper is to illuminate the contributions of Amundsen as a scientist and to celebrate his attainment of the South Pole as an explorer 100 yr ago.

  17. Assessing Embayed Equilibrium State, Beach Rotation and Environmental Forcing Influences; Tenby Southwest Wales, UK

    Directory of Open Access Journals (Sweden)

    Tony Thomas

    2016-04-01

    Full Text Available The morphological change of a headland bay beach—Tenby, West Wales, UK—was analysed over a 73-year period (1941–2014. Geo-referenced aerial photographs were used to extract shoreline positions which were subsequently compared with wave models based on storm event data. From the 1941 baseline, results showed shoreline change rates reduced over time with regression models enabling a prediction of shoreline equilibrium circa 2061. Further temporal analyses showed southern and central sector erosion and northern accretion, while models identified long-term plan-form rotation, i.e., a negative phase relationship between beach extremities and a change from negative to positive correlation within the more stable central sector. Models were then used in conjunction with an empirical 2nd order polynomial equation to predict the 2061 longshore equilibrium shoreline position under current environmental conditions. Results agreed with previous regional research which showed that dominant south and southwesterly wave regimes influence south to north longshore drift with counter drift generated by less dominant easterly regimes. The equilibrium shoreline was also used to underpin flood and inundation assessments, identifying areas at risk and strategies to increase resilience. UK shoreline management plans evaluate coastal vulnerability based upon temporal epochs of 20, 50 and 100 years. Therefore, this research evaluating datasets spanning 73 years has demonstrated the effectiveness of linear regression in integrating temporal and spatial consequences of sea level rise and storms. The developed models can be used to predict future shoreline positions aligned with shoreline management plan epochs and inform embayed beach shoreline assessments at local, regional and international scales, by identifying locations of vulnerability and enabling the development of management strategies to improve resilience under scenarios of sea level rise and climate

  18. Bathymetry and Canyons of the western Solomon Sea

    Science.gov (United States)

    Davies, H. L.; Keene, J. B.; Hashimoto, K.; Joshima, M.; Stuart, J. E.; Tiffin, D. L.

    1986-12-01

    The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m.

  19. Antarctic sea ice variability and trends, 1979–2010

    Directory of Open Access Journals (Sweden)

    D. J. Cavalieri

    2012-08-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has (like the Arctic instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but the magnitudes of the two trends differ, and in some cases these differences allow inferences about the corresponding changes in sea ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  20. White Oak Creek Embayment site characterization and contaminant screening analysis

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Ford, C.J.; Frank, M.L.; Hoffman, F.O.; Hook, L.A.

    1993-01-01

    Analyses of sediment samples collected near the mouth of White Oak Creek during the summer of 1990 revealed [sup 137]Cs concentrations [> 10[sup 6] Bq/kg dry wt (> 10[sup 4] pCi/g dry wt)] near the sediment surface. Available evidence indicates that these relatively high concentrations of [sup 137]Cs now at the sediment surface were released from White Oak Dam in the mid-1950s and had accumulated at depositionalsites in the embayment. These accumulated sediments are being eroded and transported downstream primarily during winter low-water levels by flood events and by a combination of normal downstream flow and the water turbulence created by the release of water from Melton Hill Dam during hydropower generation cycles. This report provides a more thorough characterization of the extent of contamination in WOCE than was previously available. Environmental samples collected from WOCE were analyzed for organic, inorganic, and radiological contaminants in fish, water, and sediment. These results were used to conduct a human health effects screening analysis. Walkover radiation surveys conducted inside the fenced area surrounding the WOCE at summer-pool (741 ft MSL) and at winter-pool (733 ft MSL) level, indicated a maximum exposure rate of 3 mR h[sup 1] 1 m above the soil surface.

  1. Influence of the West Antarctic Ice Sheet and its collapse on the wind and precipitation regimes of the Ross Embayment

    Science.gov (United States)

    Seles, D.; Kowalewski, D. E.

    2015-12-01

    Marine Isotope Stage 31 (MIS 31) is a key analogue for current warming trends yet the extent of the East Antarctic Ice Sheet (EAIS) and the West Antarctic Ice Sheet (WAIS) during this interglacial remains unresolved. Inconsistencies persist between offshore records (suggesting the instability of WAIS) and McMurdo Dry Valley (MDV) terrestrial datasets (indicating long-term ice sheet stability). Here we use a high-resolution regional scale climate model (RegCM3_Polar) to reconstruct paleoclimate during MIS 31 (warm orbit, 400 ppm CO2) and assess changes in precipitation and winds (including katabatic) with WAIS present versus WAIS absent. The MIS 31 scenario with WAIS present resulted in minimal changes in wind magnitude compared with current climate conditions. With WAIS absent, the model predicts a decrease in coastal and highland monthly mean average wind velocities. The greatest rates of snowfall remain along the coast but shift towards higher latitudes with the interior continent remaining dry when WAIS is removed. Focusing on the Ross Embayment, this decreased monthly mean wind velocity and shift of winds to the east indicate a greater influence of offshore winds from the Ross Sea, enabling the increase of precipitation southward along the Transantarctic Mountains (TAM) (i.e. MDV). The apparent decrease of katabatic winds with no WAIS implies that offshore winds may be responsible for bringing the warmer, wetter air into the TAM. The change in wind and precipitation in the Ross Embayment and specifically the MDV highlights the impact of WAIS on Antarctic climate and its subsequent influence on the mass balance of peripheral EAIS domes (i.e. Taylor Dome). Modeling suggests that if WAIS was absent during MIS 31, we would expect (1) greater accumulation at such domes and (2) MDV terrestrial records that reflect a wetter climate, and (3) weaker winds suggesting possibly lower ablation/erosion rates compared to if WAIS was present.

  2. Antarctic Sea Ice Variability and Trends, 1979-2010

    Science.gov (United States)

    Parkinson, C. L.; Cavalieri, D. J.

    2012-01-01

    In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978 - December 2010 reveal an overall positive trend in ice extents of 17,100 +/- 2,300 square km/yr. Much of the increase, at 13,700 +/- 1,500 square km/yr, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of -8,200 +/- 1,200 square km/yr. When examined through the annual cycle over the 32-year period 1979-2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9,100 +/- 6,300 square km/yr in February to a high of 24,700 +/- 10,000 square km/yr in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  3. Antarctic sea ice variability and trends, 1979–2010

    Directory of Open Access Journals (Sweden)

    D. J. Cavalieri

    2012-03-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  4. Mesoscale Morphological Change, Beach Rotation and Storm Climate Influences along a Macrotidal Embayed Beach

    Directory of Open Access Journals (Sweden)

    Tony Thomas

    2015-09-01

    Full Text Available Cross-shore profiles and environmental forcing were used to analyse morphological change of a headland bay beach: Tenby, West Wales (51.66 N; −4.71 W over a mesoscale timeframe (1996–2013. Beach profile variations were attuned with longer term shoreline change identified by previous research showing southern erosion and northern accretion within the subaerial zone and were statistically significant in both sectors although centrally there was little or no significance. Conversely a statistically significant volume loss was shown at all profile locations within the intertidal zone. There were negative phase relationships between volume changes at the beach extremities, indicative of beach rotation and results were statistically significant (p < 0.01 within both subaerial (R2 = 0.59 and intertidal (R2 = 0.70 zones. This was confirmed qualitatively by time-series analysis and further cross correlation analysis showed trend reversal time-lagged associations between sediment exchanges at either end of the beach. Wave height and storm events displayed summer/winter trends which explained longer term one directional rotation at this location. In line with previous regional research, environmental forcing suggests that imposed changes are influenced by variations in southwesterly wind regimes. Winter storms are generated by Atlantic southwesterly winds and cause a south toward north sediment exchange, while southeasterly conditions that cause a trend reversal are generally limited to the summer period when waves are less energetic. Natural and man-made embayed beaches are a common coastal feature and many experience shoreline changes, jeopardising protective and recreational beach functions. In order to facilitate effective and sustainable coastal zone management strategies, an understanding of the morphological variability of these systems is needed. Therefore, this macrotidal research dealing with rotational processes across the entire intertidal

  5. Gravity inversion predicts the nature of the amundsen basin and its continental borderlands near greenland

    DEFF Research Database (Denmark)

    Døssing, Arne; Hansen, Thomas Mejer; Olesen, Arne Vestergaard

    2014-01-01

    the results of 3-D gravity inversion for predicting the sediment thickness and basement geometry within the Amundsen Basin and along its borderlands. We use the recently published LOMGRAV-09 gravity compilation and adopt a process-oriented iterative cycle approach that minimizes misfit between an Earth model...... and observations. The sensitivity of our results to lateral variations in depth and density contrast of the Moho is further tested by a stochastic inversion. Within their limitations, the approach and setup used herein provides the first detailed model of the sediment thickness and basement geometry in the Arctic...... of the Eurekan Mount Rawlinson Fault in Ellesmere Island. We compute the anomalous basement topography and show evidence of deformed oceanic and continental crust in relation to this fault zone (LKFZ), suggesting that pronounced Eurekan crustal shortening took place here....

  6. Morphodynamic modeling of an embayed beach under wave group forcing

    Science.gov (United States)

    Reniers, A. J. H. M.; Roelvink, J. A.; Thornton, E. B.

    2004-01-01

    The morphodynamic response of the nearshore zone of an embayed beach induced by wave groups is examined with a numerical model. The model utilizes the nonlinear shallow water equations to phase resolve the mean and infragravity motions in combination with an advection-diffusion equation for the sediment transport. The sediment transport associated with the short-wave asymmetry is accounted for by means of a time-integrated contribution of the wave nonlinearity using stream function theory. The two-dimensional (2-D) computations consider wave group energy made up of directionally spread, short waves with a zero mean approach angle with respect to the shore normal, incident on an initially alongshore uniform barred beach. Prior to the 2-D computations, the model is calibrated with prototype flume measurements of waves, currents, and bed level changes during erosive and accretive conditions. The most prominent feature of the 2-D model computations is the development of an alongshore quasi-periodic bathymetry of shoals cut by rip channels. Without directional spreading, the smallest alongshore separation of the rip channels is obtained, and the beach response is self-organizing in nature. Introducing a small amount of directional spreading (less than 2°) results in a strong increase in the alongshore length scales as the beach response changes from self-organizing to being quasi-forced. A further increase in directional spreading leads again to smaller length scales. The hypothesized correlation between the observed rip spacing and wave group forced edge waves over the initially alongshore uniform bathymetry is not found. However, there is a correlation between the alongshore length scales of the wave group-induced quasi-steady flow circulations and the eventual alongshore spacing of the rip channels. This suggests that the scouring associated with the quasi-steady flow induced by the initial wave groups triggers the development of rip channels via a positive feedback

  7. Morphology and sedimentology of the Itaipú Embayment - Niterói/RJ

    Directory of Open Access Journals (Sweden)

    SALVADOR MARCUS VINICIUS S.

    2002-01-01

    Full Text Available Bathymetric and sedimentological data from water depths between 3 and 28 meters are the basis of a detailed bathymetric map of the Itaipú Embayment and an understanding of its sedimentary dynamics. Shallower than 16 meters the contours are parallel to the shoreline whereas the morphology of the deeper bottom is influenced by the Menina, Mãe, and Pai islands. Medium sand is prevalent, with local variations in more protected or less protected areas. Minor amount of black mud possibly derives from the Itaipú Lagoon. Siliciclastic granules and pebbles may be relict. The Itaipú Embayment's bottom morphology is controlled by stormy waves and the calmer easternmost part of the embayment presents a tendency to accumulate finer sediments.

  8. Biogenic carbon flows through the planktonic food web of the Amundsen Gulf (Arctic Ocean): A synthesis of field measurements and inverse modeling analyses

    Science.gov (United States)

    Forest, Alexandre; Tremblay, Jean-Éric; Gratton, Yves; Martin, Johannie; Gagnon, Jonathan; Darnis, Gérald; Sampei, Makoto; Fortier, Louis; Ardyna, Mathieu; Gosselin, Michel; Hattori, Hiroshi; Nguyen, Dan; Maranger, Roxane; Vaqué, Dolors; Marrasé, Cèlia; Pedrós-Alió, Carlos; Sallon, Amélie; Michel, Christine; Kellogg, Colleen; Deming, Jody; Shadwick, Elizabeth; Thomas, Helmuth; Link, Heike; Archambault, Philippe; Piepenburg, Dieter

    2011-12-01

    Major pathways of biogenic carbon (C) flow are resolved for the planktonic food web of the flaw lead polynya system of the Amundsen Gulf (southeast Beaufort Sea, Arctic Ocean) in spring-summer 2008. This period was relevant to study the effect of climate change on Arctic marine ecosystems as it was characterized by unusually low ice cover and warm sea surface temperature. Our synthesis relied on a mass balance estimate of gross primary production (GPP) of 52.5 ± 12.5 g C m -2 calculated using the drawdown of nitrate and dissolved inorganic C, and a seasonal f-ratio of 0.64. Based on chlorophyll a biomass, we estimated that GPP was dominated by phytoplankton (93.6%) over ice algae (6.4%) and by large cells (>5 μm, 67.6%) over small cells (production, zooplankton biomass and respiration, herbivory, bacterivory, vertical particle fluxes, pools of particulate and dissolved organic carbon (POC, DOC), net community production (NCP), as well as selected variables from the literature were used to evaluate the fate of size-fractionated GPP in the ecosystem. The structure and functioning of the planktonic food web was elucidated through inverse analysis using the mean GPP and the 95% confidence limits of every other field measurement as lower and upper constraints. The model computed a net primary production of 49.2 g C m -2, which was directly channeled toward dominant calanoid copepods (i.e. Calanus hyperboreus 20%, Calanus glacialis 10%, and Metridia longa 10%), other mesozooplankton (12%), microzooplankton (14%), detrital POC (18%), and DOC (16%). Bacteria required 29.9 g C m -2, a demand met entirely by the DOC derived from local biological activities. The ultimate C outflow comprised respiration fluxes (82% of the initial GPP), a small sedimentation (3%), and a modest residual C flow (15%) resulting from NCP, dilution and accumulation. The sinking C flux at the model limit depth (395 m) supplied 60% of the estimated benthic C demand (2.8 g C m -2), suggesting that

  9. Air--Sea CO2 Cycling in the Southeastern Beaufort Sea

    Science.gov (United States)

    Else, Brent Gordon Thomas

    During the fourth International Polar Year, an interdisciplinary study was conducted to examine the couplings between sea ice, ocean, atmosphere, and ecosystem in the southeastern Beaufort Sea. This thesis examines components of the system that control the air-sea exchange of carbon dioxide. Using eddy covariance measurements, we found enhanced CO2 exchange associated with new ice formation in winter flaw leads. This exchange was typically directed towards the surface, although we also measured one instance of outgassing. Sea surface dissolved CO2 measurements (pCO 2sw) in Amundsen Gulf showed significant undersaturation with respect to the atmosphere at freeze-up, followed by a slow increase over the winter until spring phytoplankton blooms caused strong undersaturation at break-up. Over the summer, pCO2sw increased until becoming slightly supersaturated due to surface warming. Along the southern margins of Amundsen Gulf and on the Mackenzie Shelf we found pCO2sw supersaturations in the fall due to wind-driven coastal upwelling. In the spring, this upwelling occurred along the landfast ice edges of Amundsen Gulf. By combining observations of enhanced winter gas exchange with observations of pCO 2sw in Amundsen Gulf, we derived an annual budget of air-sea CO2 exchange for the region. This exercise showed that uptake through the winter season was as important as the open water season, making the overall annual uptake of CO2 about double what had previously been calculated. Prior to this work, the prevailing paradigm of airsea CO2 cycling in Arctic polynya regions posited that strong CO2 absorption occurs in the open water seasons, and that a potential outgassing during the winter is inhibited by the sea ice cover. As a new paradigm, we propose that the spatial and temporal variability of many processes---including phytoplankton blooms, sea surface temperature and salinity changes, upwelling, river input, continental shelf processes, and the potential for high rates

  10. Mixing and stratification in a tropical tidal embayment subject to a distributed freshwater source

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Maren, van D.S.; Hoekstra, P.

    2011-01-01

    The Bay of Banten provides an example of a semicircular shallow tidal embayment in a tropical ROFI (Region Of Freshwater Influence), subject to a mixed, mainly diurnal tidal regime and a monsoon-driven residual circulation. A partially inactivated delta shapes the east coast of the bay and constitut

  11. Mixing and stratification in a tropical tidal embayment subject to a distributed freshwater source

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Maren, D.S. van; Hoekstra, P.

    2011-01-01

    The Bay of Banten provides an example of a semicircular shallow tidal embayment in a tropical ROFI (Region Of Freshwater Influence), subject to a mixed,mainly diurnal tidal regimeand amonsoon-driven residual circulation. A partially inactivated delta shapes the east coast of the bay and constitutes

  12. Shoreface storm morphodynamics and mega-rip evolution at an embayed beach: Bondi Beach, NSW, Australia

    Science.gov (United States)

    McCarroll, R. Jak; Brander, Robert W.; Turner, Ian L.; Leeuwen, Ben Van

    2016-03-01

    Embayed beach dynamics differ from open beaches due to the nature of headland control. Their resultant morphologies and morphodynamic behaviour are poorly understood due in part to a critical lack of surfzone and nearshore bathymetry observations. This study describes the morphodynamic storm response of a high-energy intermediate, 850 m long embayed beach over a three week period spanning a cluster of storms. A headland and subaqueous ridge protects the northern end of the beach, resulting in an alongshore wave height gradient. Contrary to existing beach state conceptual models, under energetic forcing the beach did not 'reset' or enter a 'cellular mega-rip' beach state. The protected northern end persisted in a low energy state, while the wave exposed southern section transitioned from transverse-bar-and-rip to a complex double-bar system, a process previously undescribed in the literature. Bar-rip morphology at the exposed end of the beach migrated offshore to greater depths, leaving an inner-reflective beach and longshore trough, while a mega-rip channel with 3 m relief developed at the exposed headland. The number of rip channels remained near constant over multiple storm events. Offshore sediment flux was 350 m3/m at the exposed headland and 20 m3/m at the protected end. Alongshore bathymetric non-uniformity decreased over the sub-aerial beach and inner surfzone, but increased in the outer surfzone and beyond. Suggested mechanisms for the persistence of 3D morphology during the cluster of storms include: (i) wave refraction to shore normal within the embayment; (ii) alongshore energy gradients; and (iii) pre-existing bar-rip morphology. Formation of the complex multi-bar state may be related to antecedent morphology, headland geometry, substrate gradient and localised hydrodynamic interactions near the headland. A new conceptual embayed beach state model is proposed for asymmetric, transitional embayed beaches. The model describes a pre-storm embayment where

  13. Distributed, explicit modeling of technical snow production and ski area management with the hydroclimatological model AMUNDSEN

    Science.gov (United States)

    Hanzer, Florian; Marke, Thomas; Strasser, Ulrich

    2016-04-01

    In this presentation, a module for simulating technical snow production in ski areas coupled to the spatially distributed physically based hydroclimatological model AMUNDSEN is presented. The module explicitly considers individual snow guns and distributes the produced snow along the slopes. The amount of snow produced by each device is a function of its type, of wet-bulb temperature at the location, of ski area infrastructure (in terms of water supply and pumping capacity), and of snow demand. An empirical rule in the modeling for snow production, derived from common snowmaking practices, splits the winter season into a period of maximum snowmaking and a successive period of selective on-demand snowmaking. The model is exemplarily set up for a ski area in the Schladming region (Austrian Alps) using actual snowmaking infrastructure data. Integration of these data as model variables, as well as stakeholder-defined indicators and thresholds, have been implemented as defined interfaces in a coupled component model architecture. Comparison of the model results with recordings of snowmaking operation and satellite-derived snow cover maps indicate that the model is capable of accurately simulating the real-world snowmaking practice, and the combined natural and technical snow conditions on the slopes. The explicit consideration of individual snow guns and ski area infrastructure makes the model a valuable tool for scenario applications, e.g. to assess the effects of different ski area management strategies and changes in snowmaking infrastructure for climate change impact studies.

  14. Facies analysis and sequence stratigraphy of the Asmari Formation in the northern area of Dezful Embayment, south-west Iran

    Directory of Open Access Journals (Sweden)

    Fateme Zabihi Zoeram

    2013-03-01

    Full Text Available This paper concerns the sequence stratigraphy of the Oligocene (Rupelian–Chattian–Early Miocene (Burdigalian Asmari Formation based on microfacies analysis of the sediments in the Ghale Nar Oilfield, central area of Zagros fold-thrust belt. Fourteen facies types typical for upward shallowing trend from open marine (MF 1–3, to shoal (MF 4-5, semi-restricted and restricted lagoon (MF 6–12 and finally to near-shore lagoon (MF 13-14 depositional environments were identified. Based on the environmental interpretations, we reconstructed a homoclinal ramp mainly represented by its inner and middle sectors. Facies types MF 4–14 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp influenced by wave and tide processes. MF1 (Pabdeh Formation, and 2 -3 with planktonic, large and small hyaline benthic foraminifera represent between FWWB and SWB. Four third-order depositional sequences were recognized. In this study, in order to better correlate the identified sequences with pre-defined sequences of the Asmari Formation in the Dezful Embayment and the Izeh zone that are chronologically well-defined, we use their number instead of their name. Sequence 2 mainly consists of an open marine environment in the base, followed by semi-restricted to restricted lagoonal facies. Sequences 36 are characterized by semi-restricted to restricted lagoonal facies. Moreover, the regional relative sea-level change curves correlate well with the global sea-level change curves.

  15. Twelve years of Amundsen and Bellingshausen Coast Thinning Observed with Altimetry and Photogrammetry.

    Science.gov (United States)

    Smith, B. E.; Shean, D. E.; Huth, A.; Morin, P. J.; Joughin, I. R.

    2014-12-01

    From the start of the airborne laser surveys in late 2002 until the present, the elevation record for the Amundsen Coast of Antarctica from small-footprint elevation measurements now spans more than a dozen years: Laser-altimetry measurements on tracks spaced tens of km apart are available from ATM, LVIS, and ICESat; Worldview stereophotogrammetry (SP) gives high-resolution snapshots of surface topography for selected parts of the coast, and CRYOSAT gives high-temporal-resolution, spatially dense radar measurements, at modestly lower precision than the other sensors. We present synoptic estimates of elevation change based on judicious combinations of these data. Two sets of techniques yield complementary results: Combining laser-derived elevations with SP DEMs gives an elevation-change map covering most outlets with near-annual resolution between 2003 and the present, while combining Cryosat data with SP DEMs gives a database of radar elevations with improved ambiguity resolution that we process to estimate surface elevation changes between mid 2010 and the present. Firn and accumulation models help reduce the effects of accumulation variability on the derived elevation rates, allowing estimates of steady-atmosphere ("dynamic") mass-change rates. These data reveal variable but increasing mass loss from Thwaites and Haynes glaciers, continuing mass loss from the glaciers draining into the Dotson and Crosson ice shelves, and significant losses on Alison ice stream and Ferrigno glacier on the Bellingshausen coast. There is also evidence for a recent hiatus in strong elevation change in parts of the grounding zone of Pine Island glacier, after nearly a decade of accelerating losses there. We discuss these findings in the context of measured surface speed changes and model estimates of ocean temperature variations.

  16. Designing an H-rotor type Wind Turbine for Operation on Amundsen-Scott South Pole Station

    OpenAIRE

    Wahl, Mats

    2007-01-01

    This thesis focuses on designing the turbine, tower structure and generator for an H-rotor type wind turbine. The produced power will be used for heating of drilling equipment, stored in containers, on the Amundsen-Scott South Pole Station. A 23 kW wind turbine producing 5 kW on average has been designed. Moreover, the design has been tested to be mounted on top of the container storing the drilling equipment. Climatological data have been processed to describe the wind regime in useful terms...

  17. Continental Shelf Embayments of the Eastern Margin of the Philippines; Lamon Bay Stratification & Circulation

    Science.gov (United States)

    2015-05-21

    Continental shelf embayments of the eastern margin of the Philippines; Lamon Bay stratification & circulation Arnold L. Gordon Lamont-Doherty...0275 Final Report The spatial and temporal shelf /slope interactions processes within and at the boundaries of Lamon Bay may be instrumental in the...characteristic, and shelf /slope interaction. The objectives of the Lamon Bay program, a component of the OKMC DRI, are to quantity the spatial and temporal

  18. Burrowing mayflies as indicators of ecosystem health: Status of populations in two western Lake Superior embayments

    Science.gov (United States)

    Edsall, Thomas A.; Gorman, Owen T.; Evrard, Lori M.

    2004-01-01

    The U.S. Environmental Protection Agency and Environment Canada are supporting the development of indicators of ecosystem health that can be used to report on progress in restoring and maintaining the Great Lakes ecosystem, as called for in the Great Lakes Water Quality Agreement between the United States and Canada. One indicator under development for Great Lakes mesotrophic environments is based on burrowing mayflies (Hexagenia: Ephemeroptera: Ephemeridae). In this paper, we report the results of a benthic survey in spring 2002 to determine the status of nymphal populations of Hexagenia in two western Lake Superior embayments, the St. Louis River estuary, an area with significant water-use impairments, and Chequamegon Bay, an area with no known water-use impairments. Ponar grab samples collected throughout these embayments showed nymphs were generally abundant in finely particulate, cohesive substrate (clay or mixtures of clay and sand) in both embayments. However, in the St. Louis River estuary nymphs were absent in those preferred substrates at 11 stations in the eastern portion of St. Louis Bay and the adjoining northwestern portion of the Duluth-Superior Harbor, where the sediments were variously contaminated with visible amounts of taconite pellets, paint chips, oil, or combusted coal waste (clinkers). Our results suggest that human activities have rendered those portions of the St. Louis River estuary unsuitable for habitation by Hexagenia nymphs and we recommend that trend monitoring of the nymphal population there be conducted to permit reporting on progress in restoring and maintaining the health and integrity of this Great Lakes ecosystem embayment, consistent with the intent of the Great Lakes Water Quality Agreement.

  19. Three-dimensional long-period groundmotion simulations in the upper Mississippi embayment

    Science.gov (United States)

    Macpherson, K.A.; Woolery, E.W.; Wang, Z.; Liu, P.

    2010-01-01

    We employed a 3D velocity model and 3D wave propagation code to simulate long-period ground motions in the upper Mississippi embayment. This region is at risk from large earthquakes in the New Madrid seismic zone (NMSZ) and observational data are sparse, making simulation a valuable tool for predicting the effects of large events. We undertook these simulations to estimate the magnitude of shaking likely to occur and to investigate the influence of the 3D embayment structure and finite-fault mechanics on ground motions. There exist three primary fault zones in the NMSZ, each of which was likely associated with one of the main shocks of the 1811-12 earthquake triplet. For this study, three simulations have been conducted on each major segment, exploring the impact of different epicentral locations and rupture directions on ground motions. The full wave field up to a frequency of 0.5 Hz is computed on a 200 ?? 200 ?? 50-km 3 volume using a staggered-grid finite-difference code. Peak horizontal velocity and bracketed durations were calculated at the free surface. The NMSZ simulations indicate that for the considered bandwidth, finite-fault mechanics such as fault proximity, directivity effect, and slip distribution exert the most control on ground motions. The 3D geologic structure of the upper Mississippi embayment also influences ground motion with indications that amplification is induced by the sharp velocity contrast at the basin edge.

  20. Accelerated sea-level rise from West Antarctica.

    OpenAIRE

    Thomas, R; Rignot, E.; Casassa, G; Kanagaratnam, P; Acuña, C; Akins, T; Brecher, H; E Frederick; Gogineni, P.; Krabill, W.; Manizade, S.; Ramamoorthy, H; Rivera, A.; Russell, R.; Sonntag, J

    2004-01-01

    Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into flo...

  1. Potentiometric Surface in the Sparta-Memphis Aquifer of the Mississippi Embayment, Spring 2007

    Science.gov (United States)

    Schrader, T.P.

    2008-01-01

    The most widely used aquifer for industry and public supply in the Mississippi embayment in Arkansas, Louisiana, Mississippi, and Tennessee is the Sparta-Memphis aquifer. Decades of pumping from the Sparta-Memphis aquifer have affected ground-water levels throughout the Mississippi embayment. Regional assessments of water-level data from the aquifer are important to document regional water-level conditions and to develop a broad view of the effects of ground-water development and management on the sustainability and availability of the region's water supply. This information is useful to identify areas of water-level declines, identify cumulative areal declines that may cross State boundaries, evaluate the effectiveness of ground-water management strategies practiced in different States, and identify areas with substantial data gaps that may preclude effective management of ground-water resources. A ground-water flow model of the northern Mississippi embayment is being developed by the Mississippi Embayment Regional Aquifer Study (MERAS) to aid in answering questions about ground-water availability and sustainability. The MERAS study area covers parts of eight states including Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee and covers approximately 70,000 square miles. The U.S. Geological Survey (USGS) and the Mississippi Department of Environmental Quality Office of Land and Water Resources measured water levels in wells completed in the Sparta-Memphis aquifer in the spring of 2007 to assist in the MERAS model calibration and to document regional water-level conditions. Measurements by the USGS and the Mississippi Department of Environmental Quality Office of Land and Water Resources were done in cooperation with the Arkansas Natural Resources Commission; the Arkansas Geological Survey; Memphis Light, Gas and Water; Shelby County, Tennessee; and the city of Germantown, Tennessee. In 2005, total water use from the Sparta

  2. Reflection seismic investigations of the Beaufort Sea margin, Arctic Ocean: Variable history of Quaternary ice-sheet advance

    Science.gov (United States)

    Batchelor, Christine; Dowdeswell, Julian; Pietras, Jeffrey

    2013-04-01

    The seismic stratigraphy and sedimentary architecture of the formerly-glaciated Beaufort Sea shelf and adjacent slope are investigated using a comprehensive grid of high-resolution 2-D seismic reflection data collected by ION Geophysical Corporation as part of the BeaufortSPAN East survey. Three cross-shelf troughs, representing locations of former ice streams draining a 1000 km-long section of the Laurentide Ice Sheet are examined; the Mackenzie, Amundsen Gulf and M'Clure Strait systems. These palaeo-ice streams operated during the last, Late Wisconsinan, glacial maximum and a hitherto unknown number of earlier glacial periods. Their dynamics influenced past ice-sheet configuration and may have forced abrupt climate change through transport of ice and freshwater to the Arctic Ocean. The objectives of this work are to constrain the number of ice advances through each trough, to discuss the possible timing of these events, and to examine the impact of Quaternary glaciation on the continental shelf and adjacent slope. The number of cycles of ice-sheet growth and decay varies markedly between the Mackenzie Trough on the western Beaufort Sea margin, with only two recorded events, and the Amundsen Gulf Trough to the east, with at least nine. The Mackenzie Trough was probably occupied by an ice stream during the Late Wisconsinan and either the Illinoian or Early Wisconsinan glaciation. The Amundsen Gulf ice stream was initiated earlier in the Quaternary, suggesting that the onset of cross-shelf glaciation on the eastern Beaufort Sea margin occurred significantly prior to initial glaciation of Mackenzie Trough to the west. Whereas the continental slope beyond the Mackenzie Trough lacks a significant glacial-sedimentary depocentre, major trough-mouth fans (of volumes ~10,000 km³ and ~60,000 km³) are present beyond the Amundsen Gulf and M'Clure Strait, respectively. A number of buried glacigenic landforms, including grounding-zone wedges and lateral moraines, are

  3. Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability

    Science.gov (United States)

    Meehl, Gerald A.; Arblaster, Julie M.; Bitz, Cecilia M.; Chung, Christine T. Y.; Teng, Haiyan

    2016-08-01

    Antarctic sea-ice extent has been slowly increasing in the satellite record that began in 1979. Since the late 1990s, the increase has accelerated, but the average of all climate models shows a decline. Meanwhile, the Interdecadal Pacific Oscillation, an internally generated mode of climate variability, transitioned from positive to negative, with an average cooling of tropical Pacific sea surface temperatures, a slowdown of the global warming trend and a deepening of the Amundsen Sea Low near Antarctica that has contributed to regional circulation changes in the Ross Sea region and expansion of sea ice. Here we show that the negative phase of the Interdecadal Pacific Oscillation in global coupled climate models is characterized by anomalies similar to the observed sea-level pressure and near-surface 850 hPa wind changes near Antarctica since 2000 that are conducive to expanding Antarctic sea-ice extent, particularly in the Ross Sea region in all seasons, involving a deepening of the Amundsen Sea Low. These atmospheric circulation changes are shown to be mainly driven by precipitation and convective heating anomalies related to the Interdecadal Pacific Oscillation in the equatorial eastern Pacific, with additional contributions from convective heating anomalies in the South Pacific convergence zone and tropical Atlantic regions.

  4. Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice.

    Science.gov (United States)

    Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun

    2014-01-23

    In recent decades, Antarctica has experienced pronounced climate changes. The Antarctic Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not declined, but has instead undergone a perplexing redistribution. Antarctic climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed Antarctic Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic Ocean, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change.

  5. Spatial and temporal trends in summertime climate and water quality indicators in the coastal embayments of Buzzards Bay, Massachusetts

    Science.gov (United States)

    Rheuban, J. E.; Williamson, S.; Costa, J. E.; Glover, D. M.; Jakuba, R. W.; McCorkle, D. C.; Neill, C.; Williams, T.; Doney, S. C.

    2016-01-01

    Degradation of coastal ecosystems by eutrophication is largely defined by nitrogen loading from land via surface water and groundwater flows. However, indicators of water quality are highly variable due to a myriad of other drivers, including temperature and precipitation. To evaluate these drivers, we examined spatial and temporal trends in a 22-year record of summer water quality data from 122 stations in 17 embayments within Buzzards Bay, MA (USA), collected through a citizen science monitoring program managed by Buzzards Bay Coalition. To identify spatial patterns across Buzzards Bay's embayments, we used a principle component and factor analysis and found that rotated factor loadings indicated little correlation between inorganic nutrients and organic matter or chlorophyll a (Chl a) concentration. Factor scores showed that embayment geomorphology in addition to nutrient loading was a strong driver of water quality, where embayments with surface water inputs showed larger biological impacts than embayments dominated by groundwater influx. A linear regression analysis of annual summertime water quality indicators over time revealed that from 1992 to 2013, most embayments (15 of 17) exhibited an increase in temperature (mean rate of 0.082 ± 0.025 (SD) °C yr-1) and Chl a (mean rate of 0.0171 ± 0.0088 log10 (Chl a; mg m-3) yr-1, equivalent to a 4.0 % increase per year). However, only seven embayments exhibited an increase in total nitrogen (TN) concentration (mean rate 0.32 ± 0.47 (SD) µM yr-1). Average summertime log10(TN) and log10(Chl a) were correlated with an indication that the yield of Chl a per unit total nitrogen increased with time suggesting the estuarine response to TN may have changed because of other stressors such as warming, altered precipitation patterns, or changing light levels. These findings affirm that nitrogen loading and physical aspects of embayments are essential in explaining the observed ecosystem response. However, climate

  6. NanoSIMS results from olivine-hosted melt embayments: Magma ascent rate during explosive basaltic eruptions

    Science.gov (United States)

    Lloyd, Alexander S.; Ruprecht, Philipp; Hauri, Erik H.; Rose, William; Gonnermann, Helge M.; Plank, Terry

    2014-08-01

    The explosivity of volcanic eruptions is governed in part by the rate at which magma ascends and degasses. Because the time scales of eruptive processes can be exceptionally fast relative to standard geochronometers, magma ascent rate remains difficult to quantify. Here we use as a chronometer concentration gradients of volatile species along open melt embayments within olivine crystals. Continuous degassing of the external melt during magma ascent results in diffusion of volatile species from embayment interiors to the bubble located at their outlets. The novel aspect of this study is the measurement of concentration gradients in five volatile elements (CO2, H2O, S, Cl, F) at fine-scale (5-10 μm) using the NanoSIMS. The wide range in diffusivity and solubility of these different volatiles provides multiple constraints on ascent timescales over a range of depths. We focus on four 100-200 μm, olivine-hosted embayments erupted on October 17, 1974 during the sub-Plinian eruption of Volcán de Fuego. H2O, CO2, and S all decrease toward the embayment outlet bubble, while F and Cl increase or remain roughly constant. Compared to an extensive melt inclusion suite from the same day of the eruption, the embayments have lost both H2O and CO2 throughout the entire length of the embayment. We fit the profiles with a 1-D numerical diffusion model that allows varying diffusivities and external melt concentrations as a function of pressure. Assuming a constant decompression rate from the magma storage region at approximately 220 MPa to the surface, H2O, CO2 and S profiles for all embayments can be fit with a relatively narrow range in decompression rates of 0.3-0.5 MPa/s, equivalent to 11-17 m/s ascent velocity and an 8 to 12 minute duration of magma ascent from ~ 10 km depth. A two stage decompression model takes advantage of the different depth ranges over which CO2 and H2O degas, and produces good fits given an initial stage of slow decompression (0.05-0.3 MPa/s) at high

  7. Ascent Rates from Melt Embayments: Insights into the Eruption Dynamics of Arc Volcanoes

    Science.gov (United States)

    Ruprecht, P.; Lloyd, A. S.; Hauri, E.; Rose, W. I.; Gonnermann, H. M.; Plank, T. A.

    2014-12-01

    A significant fraction of the magma that is added from the mantle to the subvolcanic plumbing system ultimately erupts at the surface. The initial volatile content of the magmas as well as the interplay between volatile loss and magma ascent plays a significant role in determining the eruption style (effusive versus explosive) as well as the magnitude of the eruption. The October 17, 1974 sub-Plinian eruption of Volcán de Fuego represents a particularly well-characterized system in terms of volatile content and magma chemistry to investigate the relation between initial water content of the magmas and the ascent rate. By modeling volatile element distribution in melt embayments through diffusion and degassing during ascent we can estimate magma ascent from the storage region in the crust to the surface. The novel aspect is the measurement of concentration gradients multiple volatile elements (in particular CO2, H2O, S) at fine-scale (5-10 μm) using the NanoSIMS. The wide range in diffusivity and solubility of these different volatiles provides multiple constraints on ascent timescales over a range of depths. H2O, CO2, and S all decrease toward the embayment outlet bubble documenting the loss of H2O and CO2 compared to an extensive melt inclusion suite from the same day of the eruption. The data is best described by a two-stage model. At high pressure (>145 MPa) decompression is slow (0.05- 0.3 MPa/s) and CO2 is bled off predominantly. At shallow levels decompression accelerates to 0.3-0.5 MPa/s at the point of H2O exsolution, which strongly affects the buoyancy of the ascending magma. The magma ascent rates presented are among the first for explosive basaltic eruptions and demonstrate the potential of the embayment method for quantifying magmatic timescales associated with eruptions of different vigor. [1] Lloyd et al. (2014) JVGR, http://dx.doi.org/10.1016/j.jvolgeores.2014.06.002

  8. Deuterium excess as a proxy for sea ice extent in the western Ross Sea, Antarctica, 1882-2006

    Science.gov (United States)

    Sinclair, K. E.; Bertler, N.; Zwartz, D.; Trompetter, B.; Millet, M.; Davy, P.

    2011-12-01

    Deuterium excess in a high-resolution ice core extracted from the Whitehall Glacier (WHG) is highly sensitive to sea ice extent since observations began in 1979. Seasonal sea ice extent has increased significantly in the Ross Sea since 1995, creating a dipole between the Ross Sea and the Amundsen and Bellinghausen Sea Coasts, which have experienced significant sea ice loss. The reasons for the spatial differences in sea ice anomalies is thought to be primarily related to the phase of the Southern Annular Mode (SAM), the primary climate driver in this sector of Antarctica, and the complex interactions of SAM with the El Niño-Southern Oscillation (ENSO). A positive phase of SAM leads to deeper low pressure anomalies in the Amundsen Sea; cooler and stronger southerly winds in the western Ross Sea, and wind-driven sea ice advance, particularly when it is reinforced by La Nina conditions. In the WHG ice core, deuterium excess has mean values of 9.5 per mil from 1979 until 1994 and 5.2 per mil after 1995. This ~5 per mil shift is concurrent with a change from negative to positive sea ice extent anomalies in the Ross Sea and a concurrent decrease in marine trace elements (Na, Mg, V, Rb). We argue that increased southerly winds since 1995 (related to a more positive SAM) have increased the area of the Ross Sea and Terra Nova Bay polynas resulting in increased sea ice extent. Because sea surface temperatures (SST) are very low over these polynas, particularly in the austral autumn and winter, the deuterium excess signal at the Whitehall Glacier is highly sensitive to the amount of local moisture input and the seasonality of this moisture contribution. Increased local moisture, with low SST, results in low deuterium excess and therefore an inverse relationship with sea ice extent. In the context of the 125-year span of the WHG record, (1882-2006), deuterium excess is markedly high (and sea ice coverage is therefore expected to have been anomalously low) in the 1950s, '60s

  9. Moving sands along a headland-embayed beach system (Algarve, Southern Portugal)

    Science.gov (United States)

    Oliveira, Sónia; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, Cristina; Moura, Delminda

    2015-04-01

    Resilience of embayed and pocket beaches located at the southernmost coast of Portugal is currently a major question to coastal management of this region. In fact, several among those beaches have been artificially fed aiming to increase the width of the beach allowing people to maintain a safe distance to the unstable rocky cliffs. The sand is dredged from the offshore (ca. 2 miles from the shoreline) representing high costs for the Portuguese government. For how long will the artificial feeding solve the problem? Which beaches are worth being nourished taking into account the morphosedimentary processes? The present work is the result of a field experiment aiming to study the efficiency of the alongshore sedimentary transport between successive embayed beaches. The experiment was performed in the very indented rocky coast of the Algarve region (Southern Portugal) and comprised two field campaigns, both in 2014, during spring tides in March and November. The Algarve coast experiences a semi-diurnal meso-tidal regime ranging from 1.3 m during neap tides to 3.5 m at spring tides and the waves approach from WSW (232°) during 72% of observations along the year, almost normal to the study area shoreline. The wave and current characteristics (significant height-Hs and Period-T for waves, velocity and direction for currents) were measured during three and six tidal cycles respectively for the first and second campaign, using two pressure transducers and one electromagnetic current meter. We used sand painted with orange fluorescent dye (100 kg in March and 200 kg in November) as tracer to track the movement of the sand along the coast. The marked sand was placed on the beach face of the westernmost beach of the study area during the first low tide of each campaign. Following, hundreds of sediment samples were collected during low tide, through the monitored period, in the nodes of a georeferenced square mesh of 10 x 20 m covering three embayed beaches. Later in the

  10. The Mississippi Embayment Regional Aquifer Study (MERAS): Documentation of a Groundwater-Flow Model Constructed to Assess Water Availability in the Mississippi Embayment

    Science.gov (United States)

    Clark, Brian R.; Hart, Rheannon M.

    2009-01-01

    The Mississippi Embayment Regional Aquifer Study (MERAS) was conducted with support from the Groundwater Resources Program of the U.S. Geological Survey Office of Groundwater. This report documents the construction and calibration of a finite-difference groundwater model for use as a tool to quantify groundwater availability within the Mississippi embayment. To approximate the differential equation, the MERAS model was constructed with the U.S. Geological Survey's modular three-dimensional finite-difference code, MODFLOW-2005; the preconditioned conjugate gradient solver within MODFLOW-2005 was used for the numerical solution technique. The model area boundary is approximately 78,000 square miles and includes eight States with approximately 6,900 miles of simulated streams, 70,000 well locations, and 10 primary hydrogeologic units. The finite-difference grid consists of 414 rows, 397 columns, and 13 layers. Each model cell is 1 square mile with varying thickness by cell and by layer. The simulation period extends from January 1, 1870, to April 1, 2007, for a total of 137 years and 69 stress periods. The first stress period is simulated as steady state to represent predevelopment conditions. Areal recharge is applied throughout the MERAS model area using the MODFLOW-2005 Recharge Package. Irrigation, municipal, and industrial wells are simulated using the Multi-Node Well Package. There are 43 streams simulated by the MERAS model. Each stream or river in the model area was simulated using the Streamflow-Routing Package. The perimeter of the model area and the base of the flow system are represented as no-flow boundaries. The downgradient limit of each model layer is a no-flow boundary, which approximates the extent of water with less than 10,000 milligrams per liter of dissolved solids. The MERAS model was calibrated by making manual changes to parameter values and examining residuals for hydraulic heads and streamflow. Additional calibration was achieved through

  11. Why is the South Orkney Island shelf (the world's first high seas marine protected area) a carbon immobilization hotspot?

    Science.gov (United States)

    Barnes, David K A; Ireland, Louise; Hogg, Oliver T; Morley, Simon; Enderlein, Peter; Sands, Chester J

    2016-03-01

    The Southern Ocean archipelago, the South Orkney Islands (SOI), became the world's first entirely high seas marine protected area (MPA) in 2010. The SOI continental shelf (~44 000 km(2) ), was less than half covered by grounded ice sheet during glaciations, is biologically rich and a key area of both sea surface warming and sea-ice losses. Little was known of the carbon cycle there, but recent work showed it was a very important site of carbon immobilization (net annual carbon accumulation) by benthos, one of the few demonstrable negative feedbacks to climate change. Carbon immobilization by SOI bryozoans was higher, per species, unit area and ice-free day, than anywhere-else polar. Here, we investigate why carbon immobilization has been so high at SOI, and whether this is due to high density, longevity or high annual production in six study species of bryozoans (benthic suspension feeders). We compared benthic carbon immobilization across major regions around West Antarctica with sea-ice and primary production, from remotely sensed and directly sampled sources. Lowest carbon immobilization was at the northernmost study regions (South Georgia) and southernmost Amundsen Sea. However, data standardized for age and density showed that only SOI was anomalous (high). High immobilization at SOI was due to very high annual production of bryozoans (rather than high densities or longevity), which were 2x, 3x and 5x higher than on the Bellingshausen, South Georgia and Amundsen shelves, respectively. We found that carbon immobilization correlated to the duration (but not peak or integrated biomass) of phytoplankton blooms, both in directly sampled, local scale data and across regions using remote-sensed data. The long bloom at SOI seems to drive considerable carbon immobilization, but sea-ice losses across West Antarctica mean that significant carbon sinks and negative feedbacks to climate change could also develop in the Bellingshausen and Amundsen seas.

  12. Variability in pulmonary function following rapid altitude ascent to the Amundsen-Scott South Pole station.

    Science.gov (United States)

    Lalande, S; Anderson, P J; Miller, A D; Ceridon, M L; Beck, K C; O'Malley, K A; Johnson, J B; Johnson, B D

    2011-09-01

    The impact of acute altitude exposure on pulmonary function is variable. A large inter-individual variability in the changes in forced expiratory flows (FEFs) is reported with acute exposure to altitude, which is suggested to represent an interaction between several factors influencing bronchial tone such as changes in gas density, catecholamine stimulation, and mild interstitial edema. This study examined the association between FEF variability, acute mountain sickness (AMS) and various blood markers affecting bronchial tone (endothelin-1, vascular endothelial growth factor (VEGF), catecholamines, angiotensin II) in 102 individuals rapidly transported to the South Pole (2835 m). The mean FEF between 25 and 75% (FEF(25-75)) and blood markers were recorded at sea level and after the second night at altitude. AMS was assessed using Lake Louise questionnaires. FEF(25-75) increased by an average of 12% with changes ranging from -26 to +59% from sea level to altitude. On the second day, AMS incidence was 36% and was higher in individuals with increases in FEF(25-75) (41 vs. 22%, P = 0.05). Ascent to altitude induced an increase in endothelin-1 levels, with greater levels observed in individuals with decreased FEF(25-75). Epinephrine levels increased with ascent to altitude and the response was six times larger in individuals with decreased FEF(25-75). Greater levels of endothelin-1 in individuals with decreased FEF(25-75) suggest a response consistent with pulmonary hypertension and/or mild interstitial edema, while epinephrine may be upregulated in these individuals to clear lung fluid through stimulation of β(2)-adrenergic receptors.

  13. Arctic and Antarctic sea ice and climate

    Science.gov (United States)

    Barreira, S.

    2014-12-01

    Principal Components Analysis in T-Mode Varimax rotated was performed on Antarctic and Arctic monthly sea ice concentration anomalies (SICA) fields for the period 1979-2014, in order to investigate which are the main spatial characteristics of sea ice and its relationship with atmospheric circulation. This analysis provides 5 patterns of sea ice for inter-spring period and 3 patterns for summer-autumn for Antarctica (69,2% of the total variance) and 3 different patterns for summer-autumn and 3 for winter-spring season for the Arctic Ocean (67,8% of the total variance).Each of these patterns has a positive and negative phase. We used the Monthly Polar Gridded Sea Ice Concentrations database derived from satellite information generated by NASA Team algorithm. To understand the links between the SICA and climate trends, we extracted the mean pressure and, temperature field patterns for the months with high loadings (positive or negative) of the sea ice patterns that gave distinct atmospheric structures associated with each one. For Antarctica, the first SICA spatial winter-spring pattern in positive phase shows a negative SICA centre over the Drake Passage and north region of Bellingshausen and Weddell Seas together with another negative SICA centre over the East Indian Ocean. Strong positive centres over the rest of the Atlantic and Indian Oceans basins and the Amundsen Sea are also presented. A strong negative pressure anomaly covers most of the Antarctic Continent centered over the Bellingshausen Sea accompanied by three positive pressure anomalies in middle-latitudes. During recent years, the Arctic showed persistent associations of sea-ice and climate patterns principally during summer. Our strongest summer-autumn pattern in negative phase showed a marked reduction on SICA over western Arctic, primarily linked to an overall increase in Arctic atmospheric temperature most pronounced over the Beaufort, Chukchi and East Siberian Seas, and a positive anomaly of

  14. A multivariate analysis of Antarctic sea ice since 1979

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

    2012-03-15

    Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

  15. Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

    NARCIS (Netherlands)

    Bense, V.F.; Gumm, L.P.; Dennis, P.; Hiscock, N.; Cremer, N.; Simon, S.

    2015-01-01

    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is app

  16. Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

    NARCIS (Netherlands)

    Bense, V.F.; Gumm, L.P.; Dennis, P.; Hiscock, N.; Cremer, N.; Simon, S.

    2016-01-01

    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is app

  17. Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

    NARCIS (Netherlands)

    Bense, V.F.; Gumm, L.P.; Dennis, P.; Hiscock, N.; Cremer, N.; Simon, S.

    2016-01-01

    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is

  18. Production of mangrove litter in a macrotidal embayment, Darwin Harbour, N.T., Australia

    Science.gov (United States)

    Woodroffe, C. D.; Bardsley, K. N.; Ward, P. J.; Hanley, J. R.

    1988-06-01

    Mangrove forests within a macrotidal embayment, Creek 'H', East Arm, in Darwin Harbour, northern Australia, can be divided into a number of assemblages corresponding to geomorphologically defined habitats. The most widespread of these are: (i) tidal creek, dominated by Camptostemon schultzii, Rhizophora stylosa and Bruguiera parviflora, with occasional massive Avicennia marina; (ii) tidal flat, dominated by mixed Ceriops tagal var. australis and Bruguiera exaristata; and (iii) hinterland margin, with a gently inclined colluvial substrate, dominated by almost monospecific Ceriops tagal var. australis. The average annual litter fall was estimated from two years of observations at a series of locations. The highest rates of litter fall, > 1000 g m -2 year -1 (dry weight), were recorded in tidal creek mangrove forests, with litter fall beneath 13 m tall Avicennia marina of 1400 g m -2 year -1. In tidal flat, mixed Ceriops tagal/Bruguiera exaristata litter fall was 745 g m -2 year -1, with approximately equal contributions from both species. In hinterland margin, litter fall varied between 686 g m -2 year -1 beneath taller Ceriops (up to 7 m) and 300 g m -2 year -1 beneath lower Ceriops (forests and shows considerable spatial variation. Leaf litter was generally low in nitrogen (N) content (

  19. Facies Analysis of Fahliyan Formation in North Dezful Embayment, Southwest Iran: Implications for Porosity Distribution

    Science.gov (United States)

    Sabouhi, M.; Jahani, D.; Taati Qurayem, F.; Aminzadeh, A.

    2009-04-01

    Fahliyan Formation (Neocomian) is one of the important hydrocarbon reservoirs of khami group in south west of Iran. This Formation has 332m thickness in type section and mainly consist of carbonate rocks. In this study, the Fahliyan Formation was investigated in subsurface section of AZN#B Well in the north Dezful Embayment (with281m thickness). Lower boundary of Fahliyan Formation with Garau Formation is continuous and the upper contact with Gadvan formation is conformable According to this study 13 carbonate microfacies and one shaily facies were recognized which are grouped into four facies associations(micro facies group). These facies associations present platform to basin depositional setting and are nominated as : A (Tidal-flat), B (Lagoon), C (Bar) and D (Open marine). Based on available data set including cutting samples, thin sections and well log analysis, it seems the Fahliyan Formation was deposited in a Carbonate shelf setting and the studied profile indicates the shallowest part of the platform. Secondary porosities due to dolomitization and Stylolitization played an important role in increasing reservoir quality of the formation. Other types of porosities occupied by later cementations and had no contribution in reservoir quality.

  20. White Oak Creek Embayment site characterization and contaminant screening analysis. Environmental Restoration Program

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Ford, C.J.; Frank, M.L.; Hoffman, F.O.; Hook, L.A.

    1993-01-01

    Analyses of sediment samples collected near the mouth of White Oak Creek during the summer of 1990 revealed {sup 137}Cs concentrations [> 10{sup 6} Bq/kg dry wt (> 10{sup 4} pCi/g dry wt)] near the sediment surface. Available evidence indicates that these relatively high concentrations of {sup 137}Cs now at the sediment surface were released from White Oak Dam in the mid-1950s and had accumulated at depositionalsites in the embayment. These accumulated sediments are being eroded and transported downstream primarily during winter low-water levels by flood events and by a combination of normal downstream flow and the water turbulence created by the release of water from Melton Hill Dam during hydropower generation cycles. This report provides a more thorough characterization of the extent of contamination in WOCE than was previously available. Environmental samples collected from WOCE were analyzed for organic, inorganic, and radiological contaminants in fish, water, and sediment. These results were used to conduct a human health effects screening analysis. Walkover radiation surveys conducted inside the fenced area surrounding the WOCE at summer-pool (741 ft MSL) and at winter-pool (733 ft MSL) level, indicated a maximum exposure rate of 3 mR h{sup 1} 1 m above the soil surface.

  1. Analysis of the Use of Wind Energy to Supplement the Power Needs at McMurdo Station and Amundsen-Scott South Pole Station, Antarctica (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, E. I.; Robichaud, R.; McLain, K.

    2005-05-01

    This poster summarizes the analysis of the inclusion of wind-driven power generation technology into the existing diesel power plants at two U.S. Antarctic research stations, McMurdo and Amundsen-Scott South Pole Station. Staff at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) conducted the analysis. Available data were obtained on the wind resources, power plant conditions, load, and component cost. We then used NREL's Hybrid2 power system modeling software to analyze the potential and cost of using wind turbine generators at the two aforementioned facilities.

  2. Conquered from the deep sea? A new deep-sea isopod species from the Antarctic shelf shows pattern of recent colonization.

    Directory of Open Access Journals (Sweden)

    Torben Riehl

    Full Text Available The Amundsen Sea, Antarctica, is amongst the most rapidly changing environments of the world. Its benthic inhabitants are barely known and the BIOPEARL 2 project was one of the first to biologically explore this region. Collected during this expedition, Macrostylis roaldi sp. nov. is described as the first isopod discovered on the Amundsen-Sea shelf. Amongst many characteristic features, the most obvious characters unique for M. roaldi are the rather short pleotelson and short operculum as well as the trapezoid shape of the pleotelson in adult males. We used DNA barcodes (COI and additional mitochondrial markers (12S, 16S to reciprocally illuminate morphological results and nucleotide variability. In contrast to many other deep-sea isopods, this species is common and shows a wide distribution. Its range spreads from Pine Island Bay at inner shelf right to the shelf break and across 1,000 m bathymetrically. Its gene pool is homogenized across space and depth. This is indicative for a genetic bottleneck or a recent colonization history. Our results suggest further that migratory or dispersal capabilities of some species of brooding macrobenthos have been underestimated. This might be relevant for the species' potential to cope with effects of climate change. To determine where this species could have survived the last glacial period, alternative refuge possibilities are discussed.

  3. The evolutionary process of the geomorphology of tidal embayments in southern Jiaodong Peninsula, China

    Science.gov (United States)

    Zhan, Chao; Yu, Junbao; Wang, Qing; Li, Yunzhao; Zhou, Di; Xing, Qinghui; Chu, Xiaojing

    2017-07-01

    Based on the theory of flood/ebb asymmetry, the evolution of the geomorphology of representative bays along the southern coast of the Jiaodong Peninsula over the last 40 years was investigated using remote sensing and geographic information system technologies. The results showed that coastal features such as tidal flats and tidal inlets in the bays changed significantly over time. The studied bays are in a ring-shaped geomorphic spatial pattern characterized by shallow water, and they were concentrically ringed by tidal flats and coastal plains before the early 1980s. Later, however, a number of ponds appeared between the coastal plains and tidal flats. The extent of sediment infill for each bay in the 1980s was greater than that in the 1970s. The conversion of flat-inlets and the erosion/deposition change of tidal inlets in these four bays during study period were not synchronized. Each bay was in a state of flood asymmetry, and both the net fine and net coarse sediment deposition took place in the 1970s. From the late 1960s to the early 1980s, Dingzi Bay was characterized by flood asymmetry, and its tidal asymmetry ratio increased. The Jinghai and the Wuleidao bays were in a state of flood asymmetry, and their tidal asymmetry ratios decreased, while Rushan Bay was in a transition state from flood to ebb asymmetry. However, intensive human activities over the last 30 years, especially the construction of coastal ponds, has greatly changed the hydrology and sedimentation of these bays, causing profound changes in geomorphic features; furthermore, these changes have guided the evolutionary process of the bays. Our results suggest that the intensive human activities were key factors that caused changes in the geomorphic evolution of the studied tidal embayments, especially the sudden change from a state of rising flood asymmetry to ebb asymmetry in Dingzi Bay.

  4. Field and Satellite Observations of the Formation and Distribution of Arctic Atmospheric Bromine Above a Rejuvenated Sea Ice Cover

    Science.gov (United States)

    Nghiem, Son V.; Rigor, Ignatius G.; Richter, Andreas; Burrows, John P.; Shepson, Paul B.; Bottenheim, Jan; Barber, David G.; Steffen, Alexandra; Latonas, Jeff; Wang, Feiyue; Stern, Gary; Clemente-Colon, Pablo; Martin, Seelye; Hall, Dorothy K.; Kaleschke, Lars; Tackett, Philip; Neumann, Gregory; Asplin, Matthew G.

    2012-01-01

    Recent drastic reduction of the older perennial sea ice in the Arctic Ocean has resulted in a vast expansion of younger and saltier seasonal sea ice. This increase in the salinity of the overall ice cover could impact tropospheric chemical processes. Springtime perennial ice extent in 2008 and 2009 broke the half-century record minimum in 2007 by about one million km2. In both years seasonal ice was dominant across the Beaufort Sea extending to the Amundsen Gulf, where significant field and satellite observations of sea ice, temperature, and atmospheric chemicals have been made. Measurements at the site of the Canadian Coast Guard Ship Amundsen ice breaker in the Amundsen Gulf showed events of increased bromine monoxide (BrO), coupled with decreases of ozone (O3) and gaseous elemental mercury (GEM), during cold periods in March 2008. The timing of the main event of BrO, O3, and GEM changes was found to be consistent with BrO observed by satellites over an extensive area around the site. Furthermore, satellite sensors detected a doubling of atmospheric BrO in a vortex associated with a spiral rising air pattern. In spring 2009, excessive and widespread bromine explosions occurred in the same region while the regional air temperature was low and the extent of perennial ice was significantly reduced compared to the case in 2008. Using satellite observations together with a Rising-Air-Parcel model, we discover a topographic control on BrO distribution such that the Alaskan North Slope and the Canadian Shield region were exposed to elevated BrO, whereas the surrounding mountains isolated the Alaskan interior from bromine intrusion.

  5. Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

    OpenAIRE

    2015-01-01

    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of heliu...

  6. Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

    OpenAIRE

    2016-01-01

    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7 × 10−4 cm3 (STP) g–1 ± 2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of heliu...

  7. Fjord water circulation patterns and dysoxic/anoxic conditions in a Mediterranean semi-enclosed embayment in the Amvrakikos Gulf, Greece

    Science.gov (United States)

    Ferentinos, George; Papatheodorou, George; Geraga, Maria; Iatrou, Margarita; Fakiris, Elias; Christodoulou, Dimitris; Dimitriou, Evagelos; Koutsikopoulos, Constantin

    2010-08-01

    Oceanographic research in the Amvrakikos Gulf in Western Greece, a semi-enclosed embayment isolated from the Ionian Sea by a narrow, shallow sill, has shown that it is characterised by a fjord-like oceanographic regime. The Gulf is characterised by a well-stratified two layer structure in the water column made up of a surface layer and a bottom layer that are separated by a strong pycnocline. At the entrance over the sill, there is a brackish water outflow in the surface water and a saline water inflow in the near-bed region. This morphology and water circulation pattern makes the Amvrakikos Gulf the only Mediterranean Sea fjord. The investigations have also shown that the surface layer is well oxygenated, whereas in the pycnocline, the dissolved oxygen (DO) declines sharply and finally attains a value of zero, thus dividing the water column into oxic, dysoxic and anoxic environments. At the dysoxic/anoxic interface, at a depth of approximately 35 m, a sharp redox cline develops with Eh values between 0 and 120 mV occurring above and values between 0 and -250 mV occurring below, where oxic and anoxic biochemical processes prevail, respectively. On the seafloor underneath the anoxic waters, a black silt layer and a white mat cover resembling Beggiatoa-like cells are formed. The dysoxic/anoxic conditions appeared during the last 20 to 30 years and have been caused by the excessive use of fertilisers, the increase in animal stocks, intensive fish farming and domestic effluents. The inflicted dysoxia/anoxia has resulted in habitat loss on the seafloor over an area that makes up just over 50% of the total Gulf area and approximately 28% of the total water volume. Furthermore, anoxia is also considered to have been responsible for the sudden fish mortality which occurred in aquaculture rafts in the Gulf in February 2008. Therefore, anoxic conditions can be considered to be a potential hazard to the ecosystem and to the present thriving fishing and mariculture industry in

  8. Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

    DEFF Research Database (Denmark)

    van der Molen, J.; van Beek, J.; Augustine, Starrlight

    2015-01-01

    with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large...... numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality...

  9. Petrophysical Evaluation of the Sarvak Formation Based on Well Logs in Dezful Embayment, Zagros Fold Zone, South West of Iran

    Directory of Open Access Journals (Sweden)

    A. Jooybari

    2017-02-01

    Full Text Available Dezful embayment in the south west of Iran is part of Zagros fold zone which despite the small area includes almost all of Iran oil production. Sarvak Formation with middle cretaceous (Albin-Turunin is the second biggest reservoir of Zagros basin, after the Asmari formation. In this study, with well logging data of two wells, by Geolog software, the petrophysical parameters of Sarvak Formation in the Dezful embayment was studied using the contingent Probabilistic method. Petrophysical parameters such as determination of porosity, water saturation, shale volume and lithology were calculated using this data and common cross plots. Based on this evaluation and utilizing cross plots result, the lithology of Sarvak formation in this zone was determined to be Limestone with traces of dolomite and shale. According to the calculated petrophysical properties of the reservoir, and for more accurate assessment, Sarvak Formation was divided to 6 sections. Findings of this research show that Sarvak Formation includes good reservoir parameters only in half its sections (sections 4, 2 and 6.

  10. Assessing condition of macroinvertebrate communities and bed sediment toxicity in the Rochester Embayment Area of Concern, New York, USA

    Science.gov (United States)

    Duffy, Brian; George, Scott D.; Baldigo, Barry P.; Smith, Alexander J.

    2017-01-01

    The United States and Canada agreed to restore the chemical, physical, and biological integrity of the Great Lakes ecosystem under the first Great Lakes Water Quality Agreement in 1972. The lowest reach of the Genesee River and the Rochester Embayment on Lake Ontario between Bogus Point and Nine Mile Point, including Braddock Bay, were designated as an Area of Concern (AOC) due to effects of contaminated sediments and physical disturbance on several beneficial uses. Following sediment remedial efforts and with conditions improving in the AOC, the present study was conducted to reevaluate the status of the benthic macroinvertebrate (benthos) beneficial use impairment (BUI). Benthic macroinvertebrate community assessments and 10-day Chironomus dilutus bioassays were used to test the hypotheses that sediments within the AOC were no more toxic than sediments from surrounding reference areas. The study was separated into three discrete systems (Genesee River, Lake Ontario, and Braddock Bay) and non-parametric analyses determined that a multimetric index of benthic macroinvertebrate community integrity was significantly higher at AOC sites compared to reference sites on the Genesee River and in Braddock Bay while AOC and reference sites on Lake Ontario did not differ significantly. Survival and growth of C. dilutus were also similar between AOC and reference sites for each system with the exception of significantly higher growth at reference sites on Lake Ontario. Results generally indicated that the condition of benthos and toxicity of sediment of the Rochester Embayment AOC are similar to or better than that in the surrounding area.

  11. Seismic anisotropy beneath the Mississippi Embayment and the New Madrid Seismic Zone: A study of shear wave splitting

    Science.gov (United States)

    Nyamwandha, Cecilia A.; Powell, Christine A.

    2016-11-01

    Shear wave splitting associated with the Mississippi Embayment (ME) is determined using teleseismic SKS phases recorded by the Northern Embayment Lithosphere Experiment (NELE), the USArray Transportable Array (TA), and the New Madrid seismic network for the period 2005-2016. Our data set consists of 5900 individual splitting measurements from 257 earthquakes recorded at 151 stations within and outside the ME. Stations outside of the ME exhibit significant shear wave splitting, with average delay times between 0.4 s and 1.8 s. To the northeast and east of the ME, nearly all observed fast orientations are approximately oriented northeast-southwest, in agreement with absolute plate motion (APM) predicted by HS3-Nuvel-1A. The homogeneity of the fast orientations in this region suggests that the splitting is due to active flow in the asthenosphere. A counterclockwise rotation in the splitting orientation is observed moving northeast to northwest across the study area. Inside the ME, some stations show large and systematic deviations of the measured fast orientations from the APM. The delay times within the entire ME range from 0.9 s to 2.1 s. Splitting complexity is attributed to relic lithospheric fabrics formed during past tectonic events including passage of a hot spot in mid-Cretaceous time. The anisotropy may also be linked to the presence of a southwest dipping region of low P and S wave velocities below the ME or to deeper flow in the asthenosphere.

  12. Comparative diel feeding ecology of brook silverside, golden shiner, and subyearling pumpkinseed in a Lake Ontario embayment during summer

    Science.gov (United States)

    Johnson, James H.; Chalupnicki, Marc; Abbett, Ross; Diaz, Avriel R; Nack, Christopher C

    2017-01-01

    Fish feeding ecology has been shown to vary over a 24-h period in terms of the prey consumed and feeding intensity. Consequently, in order to best determine the interspecific feeding associations within a fish community, examination of the diet at multiple times over a 24-h period is often necessary. We examined the diel feeding ecology of three fish species that were numerically dominant in a Lake Ontario embayment during summer. The diet of each of the three species, subyearling pumpkinseed Lepomis gibbosus, golden shiner Notemigonus crysoleucus, and brook silverside Labidesthes sicculus, was distinct with no significant overlap in diet composition occurring within any of the 4-h time intervals. The diet composition of each species suggested that brook silverside were feeding at the surface (terrestrial invertebrates and aquatic surface dwelling hemipterans) whereas subyearling pumpkinseed (amphipods) and golden shiner (tipulids) were feeding on different benthic prey. Differences in feeding periodicity were most pronounced for subyearling pumpkinseed. Our findings provide valuable insights on interspecific feeding associations among these three fish species during summer in a Lake Ontario embayment.

  13. The Trobriand Subduction System in the Western Solomon Sea

    Science.gov (United States)

    Lock, J.; Davies, H. L.; Tiffin, D. L.; Murakami, F.; Kisimoto, K.

    1987-09-01

    A south-dipping Subduction system which underlies the Trobriand Trough and 149° Embayment, on the southern margin of the Solomon Sea, is active or was recently active. Oceanic basement is overlain by 2.5 s, two-way travel time (TWTT), of sediment that shows at least two stages of deformation: early thrusts (inner wall) and normal faults (outer wall), and later normal faults that have elevated the outer trench margin. Thrust anticlines and slope basins are developed on the inner wall. The floor of the Solomon Sea Basin arches upward between the Trobriand Trough and the New Britain Trench to form isolated peaks and ridges in the east (152° Peaks) and an east-west Central Ridge in the west. Structures in the subduction system, and in the Solomon Sea Basin, plunge westward towards the point of collision with the New Britain Trench.

  14. Bellingshausen Sea ice extent recorded in an Antarctic Peninsula ice core

    Science.gov (United States)

    Porter, Stacy E.; Parkinson, Claire L.; Mosley-Thompson, Ellen

    2016-12-01

    Annual net accumulation (An) from the Bruce Plateau (BP) ice core retrieved from the Antarctic Peninsula exhibits a notable relationship with sea ice extent (SIE) in the Bellingshausen Sea. Over the satellite era, both BP An and Bellingshausen SIE are influenced by large-scale climatic factors such as the Amundsen Sea Low, Southern Annular Mode, and Southern Oscillation. In addition to the direct response of BP An to Bellingshausen SIE (e.g., more open water as a moisture source), these large-scale climate phenomena also link the BP and the Bellingshausen Sea indirectly such that they exhibit similar responses (e.g., northerly wind anomalies advect warm, moist air to the Antarctic Peninsula and neighboring Bellingshausen Sea, which reduces SIE and increases An). Comparison with a time series of fast ice at South Orkney Islands reveals a relationship between BP An and sea ice in the northern Weddell Sea that is relatively consistent over the twentieth century, except when it is modulated by atmospheric wave patterns described by the Trans-Polar Index. The trend of increasing accumulation on the Bruce Plateau since 1970 agrees with other climate records and reconstructions in the region and suggests that the current rate of sea ice loss in the Bellingshausen Sea is unrivaled in the twentieth century.

  15. A large CO2 sink enhanced by eutrophication in a tropical coastal embayment (Guanabara Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    L. C. Cotovicz Jr.

    2015-03-01

    Full Text Available In contrast to its small surface area, the coastal zone plays a disproportionate role in the global carbon cycle. Carbon production, transformation, emission and burial rates at the land–ocean interface are still poorly known, especially in tropical regions. Surface water pCO2 and ancillary parameters were monitored during nine field campaigns between April 2013 and April 2014 in Guanabara Bay, a tropical eutrophic to hypertrophic semi-enclosed estuarine embayment surrounded by the city of Rio de Janeiro, SE-Brazil. Water pCO2 varied between 22 and 3715 ppmv in the Bay showing spatial, diurnal and seasonal trends that mirrored those of dissolved oxygen (DO and Chlorophyll a (Chl a. Marked pCO2 undersaturation was prevalent in the shallow, confined and thermally stratified waters of the upper bay, whereas pCO2 oversaturation was restricted to sites close to the small river mouths and small sewage channels, which covered only 10% of the bay's area. Substantial daily variations in pCO2 (up to 395 ppmv between dawn and dusk were also registered and could be integrated temporally and spatially for the establishment of net diurnal, seasonal and annual CO2 fluxes. In contrast to other estuaries worldwide, Guanabara Bay behaved as a net sink of atmospheric CO2, a property enhanced by the concomitant effects of strong radiation intensity, thermal stratification, and high availability of nutrients, which promotes phytoplankton development and net autotrophy. In the inner part of the bay, the calculated annual CO2 sink (−19.6 mol C m2 yr-1 matched the organic carbon burial in the sediments reported in the literature. The carbon sink and autotrophy of Guanabara Bay was driven by planktonic primary production promoted by eutrophication, and by its typology of marine embayment lacking the classical extended estuarine mixing zone, in contrast to river-dominated estuarine systems, which are generally net heterotrophic and CO2 emitters. Our results show that

  16. Ocean measurements in the Ross and Amundsen Seas, NATHANIEL B PALMER Cruise 07-02, 03 February - 26 March 2007 (NODC Accession 0049900)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We are reporting ocean CTD/O profiles and salinity, dissolved oxygen and nutrient measurements from rosette water bottles at 190 stations occupied from the western...

  17. Wildlife, urban inputs, and landscape configuration are responsible for degraded swimming water quality at an embayed beach

    Science.gov (United States)

    Byappanahalli, Muruleedhara N.; Nevers, Meredith; Whitman, Richard L.; Ge, Zhongfu; Shively, Dawn A.; Spoljaric, Ashley; Przybyla-Kelly, Katarzyna

    2015-01-01

    Jeorse Park Beach, on southern Lake Michigan, experiences frequent closures due to high Escherichia coli (E. coli) levels since regular monitoring was implemented in 2005. During the summer of 2010, contaminant source tracking techniques, such as the conventional microbial and physical surveys and hydrodynamic models, were used to determine the reasons for poor water quality at Jeorse Park. Fecal indicator bacteria (E. coli, enterococci) were high throughout the season, with densities ranging from 12–2419 (culturable E. coli) and 1–2550 and < 1–5831 (culturable and qPCR enterococci, respectively). Genetic markers for human (Bacteroides HF183) and gull (Catellicoccus marimammalium) fecal contamination were found in 15% and 37% of the samples indicating multiple sources contributing to poor water quality. Nesting colonies of double-crested cormorants (Phalacrocorax auritus) have steadily increased since 2005, coinciding with high E. colilevels. A hydrodynamic model indicated that limited circulation allows bacteria entering the embayed area to be retained in nearshore areas; and bacterial resuspension from sand and stranded beach wrack during storm events compounds the problem. The integration of hydrodynamics, expanded use of chemical and biological markers, as well as more complex statistical multivariate techniques can improve microbial source tracking, informing management actions to improve recreational water quality. Alterations to embayed structures to improve circulation and reduce nuisance algae as well as growing native plants to retain sand to improve beach morphometry are among some of the restoration strategies under consideration in ongoing multi-agency collaborations.

  18. Do higher erosion rates lead to topographic highs or lows? An example from the Puli Embayment, West-Central Taiwan

    Science.gov (United States)

    Upton, P.; Mueller, K.; Tucker, G.; Wilcox, T.; Yanites, B.

    2006-12-01

    The Puli embayment, a 50 km wide, 1500m deep depression within the Foothills belt, Hsueshan Range and Backbone Ranges of western Taiwan, coincides with a >50 mgal negative bouguer gravity anomaly. The gravity low is consistent with a deep basin filled with lower density sediment, likely inherited from the passive margin presently being caught up in the collision between the Eurasian margin and the Luzon Arc forming Taiwan. The topography, specifically the Puli embayment, suggests the existence of an along strike variation in one or more of the parameters which control wedge development; the strength of the basal decollement or wedge material, the dip of the basal decollement or erosion rates. Three dimensional mechanical models show that a region of lower density fill within the outboard wedge of an actively deforming two-sided wedge will experience relatively more uplift while the main divide region behind the basin will experience relatively less uplift, the opposite of what is observed in Puli. It has previously been suggested that increased erosion was associated with this region of relatively lower relief. Localised high erosion rates have been shown to significantly influence the mechanical behaviour of collisional mountain belts on timescales of 1-5Ma where the wavelength of the erosional signal is on the order of the thickness of the brittle crust. Crustal aneurysms, such as those recognised in the indentor corners of the Himalaya, link enhanced erosion rates with the topographic highs of Nanga Parbat and Namche Bawa. Development of such an aneurysm is dependant upon both rapid uplift of hot lower crustal rocks and continued high erosion rates. While erosion rates in the Puli may have been higher in the past, leading to the topographic hole, they appear to have slowed in the last 50 ka, possibly due to a reduction in the rainfall associated with the lower topography, unlike the indentor corners where orogen-scale rivers maintain enhanced erosion rates.

  19. Toxicity of waters from the Rochester Embayment Area of Concern to the plankton species Pseudokirchneriella subcapitata and Ceriodaphnia dubia

    Science.gov (United States)

    Baldigo, Barry P.; Duffy, Brian T.; Smith, Alexander J; George, Scott D.

    2016-01-01

    The lower Genesee River and Rochester Embayment of Lake Ontario are a designated Area of Concern (AOC) under the binational Great Lakes Water Quality Agreement. The “degradation of phytoplankton and zooplankton populations” or plankton Beneficial Use Impairment (BUI) was classified as unknown and in need of further assessment in this AOC because water quality data suggested plankton communities could be effected and community data were either unavailable or indicated impacts. The plankton BUI may now be obsolete because local contaminant sources have been largely eliminated. The present study was conducted between July 2013 and August 2014 to assess the BUI-removal criteria: “AOC plankton bioassays confirm that toxicity in ambient waters (i.e., no growth inhibition) is not significantly higher than comparable non-AOC controls”. Acute and chronic toxicity of waters from 13 sites were quantified seasonally using standardized bioassays with the green alga Pseudokirchneriella subcapitata and water flea Ceriodaphnia dubia to test the hypothesis that toxicity of waters from AOC sites was not higher than that of waters from comparable non-AOC reference sites. Survival and reproduction of C. dubia did not differ significantly between site types, systems, or months. The growth of P. subcapitata did not differ between site types, but differed among systems and months. All results indicate that waters from AOC sites were no more toxic to both plankton species than waters from reference sites. Assuming test species represent natural plankton assemblages, water quality should not negatively affect survival and growth of resident plankton populations in the Rochester Embayment AOC.

  20. Can a city combat sea level rise alone: the impact of higher seawalls on the neighbors?

    Science.gov (United States)

    Wang, R. Q.; Stacey, M. T.; Herdman, L.; Hummel, M.; Erikson, L. H.; Barnard, P.

    2016-12-01

    Global mean sea level has been rising by an average of 2 mm every year since 1993. This trend is observed to be accelerating in recent years, and the mean sea level rise is projected to be 1 m by 2100. Coastal communities are beginning to plan for protections against this threat, often requiring alterations to the structure of protective shorelines. As each community takes action, it is not clear how much an individual project (i.e., construction of a seawall, restoration of a marsh, etc. ) changes the regional hydrodynamics and how much the aggregated effects of other communities' projects influence a particular city. Because tidal forcing interacts with the geometry of a coastal embayment, alterations to the shoreline may increase (or decrease) flood risk regionally. There may be even more direct influences between neighboring communities, if the risk of inundation of one increases the risk for the other. This spatial interdependence has been largely neglected in coastal community planning, due in large part to a lack of quantitative information on the interdependence of communities. We have developed a suite of numerical methodologies to address this issue. A Bay-scale model has been established to reproduce the tidal and inundation dynamics under various scenarios for sea level rise. By considering different shoreline configurations, we can evaluate the impact of both local and regional actions on water level and inundation risk. For example, a complete hardening of embayment shores (i.e., a seawall ringing the entire embayment) increases water levels moderately for all communities, increasing the necessary investment in shoreline protections. To complement the forward model calculations, we have developed an adjoint sensitivity analysis tool that can efficiently analyze the importance of all the other coastal projects on a particular city. The quantification of these interdependencies demonstrate the value of coordinated action by communities, and the role

  1. Landscape evolution in tidal embayments: Modeling the interplay of erosion, sedimentation, and vegetation dynamics

    Science.gov (United States)

    D'Alpaos, Andrea; Lanzoni, Stefano; Marani, Marco; Rinaldo, Andrea

    2007-03-01

    We propose an ecomorphodynamic model which conceptualizes the chief land-forming processes operating on the intertwined, long-term evolution of marsh platforms and embedded tidal networks. The rapid network incision (previously addressed by the authors) is decoupled from the geomorphological dynamics of intertidal areas, governed by sediment erosion and deposition and crucially affected by the presence of vegetation. This allows us to investigate the response of tidal morphologies to different scenarios of sediment supply, colonization by halophytes, and changing sea level. Different morphological evolutionary regimes are shown to depend on marsh ecology. Marsh accretion rates, enhanced by vegetation growth, and the related platform elevations tend to decrease with distance from the creek, measured along suitably defined flow paths. The negative feedback between surface elevation and its inorganic accretion rate is reinforced by the relation between plant productivity and soil elevation in Spartina-dominated marshes and counteracted by positive feedbacks in multispecies-vegetated marshes. When evolving under constant sea level, unvegetated and Spartina-dominated marshes asymptotically tend to mean high water level (MHWL), different from multiple vegetation species marshes, which can make the evolutionary transition to upland. Equilibrium configurations below MHWL can be reached under constant rates of sea level rise, depending on sediment supply and vegetation productivity. Our analyses on marine regressions and transgressions show that when the system is in a supply-limited regime, network retreat and expansion (associated with regressions and transgressions, respectively) tend to be cyclic. Conversely, in a transport-limited regime, network reexpansion following a regression tends to take on a new configuration, showing a hysteretic behavior.

  2. Geodatabase of the datasets used to represent the six subunits of the Texas Coastal Uplands and Mississippi Embayment aquifer system, Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, Tennessee, and Texas

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This geodatabase includes spatial datasets that represent the Texas Coastal Uplands and Mississippi Embayment aquifer system in the States of Alabama, Arkansas,...

  3. Storm-induced sea-ice breakup and the implications for ice extent

    Science.gov (United States)

    Kohout, A. L.; Williams, M. J. M.; Dean, S. M.; Meylan, M. H.

    2014-05-01

    The propagation of large, storm-generated waves through sea ice has so far not been measured, limiting our understanding of how ocean waves break sea ice. Without improved knowledge of ice breakup, we are unable to understand recent changes, or predict future changes, in Arctic and Antarctic sea ice. Here we show that storm-generated ocean waves propagating through Antarctic sea ice are able to transport enough energy to break sea ice hundreds of kilometres from the ice edge. Our results, which are based on concurrent observations at multiple locations, establish that large waves break sea ice much farther from the ice edge than would be predicted by the commonly assumed exponential decay. We observed the wave height decay to be almost linear for large waves--those with a significant wave height greater than three metres--and to be exponential only for small waves. This implies a more prominent role for large ocean waves in sea-ice breakup and retreat than previously thought. We examine the wider relevance of this by comparing observed Antarctic sea-ice edge positions with changes in modelled significant wave heights for the Southern Ocean between 1997 and 2009, and find that the retreat and expansion of the sea-ice edge correlate with mean significant wave height increases and decreases, respectively. This includes capturing the spatial variability in sea-ice trends found in the Ross and Amundsen-Bellingshausen seas. Climate models fail to capture recent changes in sea ice in both polar regions. Our results suggest that the incorporation of explicit or parameterized interactions between ocean waves and sea ice may resolve this problem.

  4. Analysis of the projected regional sea-ice changes in the Southern Ocean during the twenty-first century

    Energy Technology Data Exchange (ETDEWEB)

    Lefebvre, W.; Goosse, H. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium)

    2008-01-15

    Using the set of simulations performed with atmosphere-ocean general circulation models (AOGCMs) for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), the projected regional distribution of sea ice for the twenty-first century has been investigated. Averaged over all those model simulations, the current climate is reasonably well reproduced. However, this averaging procedure hides the errors from individual models. Over the twentieth century, the multimodel average simulates a larger sea-ice concentration decrease around the Antarctic Peninsula compared to other regions, which is in qualitative agreement with observations. This is likely related to the positive trend in the Southern Annular Mode (SAM) index over the twentieth century, in both observations and in the multimodel average. Despite the simulated positive future trend in SAM, such a regional feature around the Antarctic Peninsula is absent in the projected sea-ice change for the end of the twenty-first century. The maximum decrease is indeed located over the central Weddell Sea and the Amundsen-Bellingshausen Seas. In most models, changes in the oceanic currents could play a role in the regional distribution of the sea ice, especially in the Ross Sea, where stronger southward currents could be responsible for a smaller sea-ice decrease during the twenty-first century. Finally, changes in the mixed layer depth can be found in some models, inducing locally strong changes in the sea-ice concentration. (orig.)

  5. Hammer-Impact SH-Wave Seismic Reflection Methods in Neotectonic Investigations: General Observations and Case Histories from the Mississippi Embayment, U.S.A.

    Institute of Scientific and Technical Information of China (English)

    James B Harris

    2009-01-01

    Shallow shear-wave seismic reflection imaging, using a sledgehammer and mass energy source and standard processing, has become increasingly common in mapping near-surface geologic features, especially in water-saturated, unconsolidated sediments. Tests of the method in the Mississippi Embayment region of the central United States show Interpretable reflection arrivals in the depth range of 100 m with the potential for increased resolution when compared with compresslonal-wave data. Shear-wave reflection profiles were used to help interpret the significance of neotectonic surface deformation at five sites in the Mississippi Embayment. The interpreted profiles show a range of shallow structural styles that include reverse faulting, fault propagation folding, and reactivated normal faulting, and provide crucial subsurface evidence in support of paleuseismologic trenching and shallow drilling.

  6. Analysis of the Use of Wind Energy to Supplement the Power Needs at McMurdo Station and Amundsen-Scott South Pole Station, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, I.; Robichaud, R.; McLain, K.

    2005-05-01

    This report summarizes an analysis of the inclusion of wind-driven power generation technology into the existing diesel power plants at two U.S. Antarctic research stations, McMurdo and Amundsen-Scott South Pole Station. Staff at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) conducted the analysis. Raytheon Polar Services, which currently holds the private sector support contract for the two research stations, was a major contributor to this report. To conduct the analysis, available data were obtained on the wind resources, power plant conditions, load, and component cost. Whenever possible, we validated the information. We then used NREL's Hybrid2 power system modeling software to analyze the potential and cost of using wind turbine generators at the two aforementioned facilities. Unfortunately, the power systems and energy allocations at McMurdo and South Pole Station are being redeveloped, so it is not possible to validate future fuel use. This report is an initial assessment of the potential use of wind energy and should be followed by further, more detailed analysis if this option is to be considered further.

  7. Under-ice ambient noise in Eastern Beaufort Sea, Canadian Arctic, and its relation to environmental forcing.

    Science.gov (United States)

    Kinda, G Bazile; Simard, Yvan; Gervaise, Cédric; Mars, Jérome I; Fortier, Louis

    2013-07-01

    This paper analyzes an 8-month time series (November 2005 to June 2006) of underwater noise recorded at the mouth of the Amundsen Gulf in the marginal ice zone of the western Canadian Arctic when the area was >90% ice covered. The time-series of the ambient noise component was computed using an algorithm that filtered out transient acoustic events from 7-min hourly recordings of total ocean noise over a [0-4.1] kHz frequency band. Under-ice ambient noise did not respond to thermal changes, but showed consistent correlations with large-scale regional ice drift, wind speed, and measured currents in upper water column. The correlation of ambient noise with ice drift peaked for locations at ranges of ~300 km off the mouth of the Amundsen Gulf. These locations are within the multi-year ice plume that extends westerly along the coast in the Eastern Beaufort Sea due to the large Beaufort Gyre circulation. These results reveal that ambient noise in Eastern Beaufort Sea in winter is mainly controlled by the same meteorological and oceanographic forcing processes that drive the ice drift and the large-scale circulation in this part of the Arctic Ocean.

  8. West Antarctic Ice Sheet retreat from Pine Island Bay during the Holocene: New insights into forcing mechanisms

    Science.gov (United States)

    Hillenbrand, Claus-Dieter; Smith, James; Kuhn, Gerhard; Poole, Chris; Hodell, David; Elderfield, Harry; Kender, Sev; Williams, Mark; Peck, Victoria; Larter, Robert; Klages, Johann; Graham, Alastair; Forwick, Matthias; Gohl, Karsten

    2013-04-01

    The Amundsen Sea sector of the largely marine-based and therefore conditionally unstable West Antarctic Ice Sheet (WAIS) contains enough ice to raise global sea level by ca. 1.5 metres. At present, ice streams draining this sector into the Southern Ocean, especially glaciers flowing into Pine Island Bay in the eastern Amundsen Sea embayment, are undergoing considerable mass loss characterised by major thinning, flow acceleration and rapid grounding-line retreat. Sub-ice shelf melting by relatively warm Circumpolar Deep Water (CDW) upwelling onto the continental shelf is held responsible for these dynamical changes but atmospheric warming in West Antarctica may also have contributed to them. In contrast to the modern situation, the long-term history of the Amundsen Sea sector and the mechanisms forcing its deglaciation during the Holocene are only poorly constrained. We will present new palaeoenvironmenal data obtained from marine sediment cores collected in Pine Island Bay. The cores targeted shallow sites on the inner continental shelf and successfully recovered sedimentary sequences bearing calcareous microfossils. Radiocarbon ages on these microfossils demonstrate that the grounding line of the WAIS retreated to within ~100 km of its modern position before ca. 10 kyr BP (thousand years before present), which is consistent with an early WAIS retreat from near-coastal locations in the western Amundsen Sea embayment. Currently, there is no evidence that the grounding line had retreated landward of its modern position during the Holocene. Therefore, the chronological constraints may imply that during the last 10 kyr any episodes of fast grounding-line retreat similar to those observed today were short-lived and rare. Preliminary geochemical data from benthic and planktonic foraminifera tests in the cores from Pine Island Bay reveals that intense CDW upwelling coincided with and may have forced the deglaciation of the inner continental shelf. Furthermore, we observe

  9. Ice sheet systems and sea level change.

    Science.gov (United States)

    Rignot, E. J.

    2015-12-01

    Modern views of ice sheets provided by satellites, airborne surveys, in situ data and paleoclimate records while transformative of glaciology have not fundamentally changed concerns about ice sheet stability and collapse that emerged in the 1970's. Motivated by the desire to learn more about ice sheets using new technologies, we stumbled on an unexplored field of science and witnessed surprising changes before realizing that most were coming too fast, soon and large. Ice sheets are integrant part of the Earth system; they interact vigorously with the atmosphere and the oceans, yet most of this interaction is not part of current global climate models. Since we have never witnessed the collapse of a marine ice sheet, observations and exploration remain critical sentinels. At present, these observations suggest that Antarctica and Greenland have been launched into a path of multi-meter sea level rise caused by rapid climate warming. While the current loss of ice sheet mass to the ocean remains a trickle, every mm of sea level change will take centuries of climate reversal to get back, several major marine-terminating sectors have been pushed out of equilibrium, and ice shelves are irremediably being lost. As glaciers retreat from their salty, warm, oceanic margins, they will melt away and retreat slower, but concerns remain about sea level change from vastly marine-based sectors: 2-m sea level equivalent in Greenland and 23-m in Antarctica. Significant changes affect 2/4 marine-based sectors in Greenland - Jakobshavn Isb. and the northeast stream - with Petermann Gl. not far behind. Major changes have affected the Amundsen Sea sector of West Antarctica since the 1980s. Smaller yet significant changes affect the marine-based Wilkes Land sector of East Antarctica, a reminder that not all marine-based ice is in West Antarctica. Major advances in reducing uncertainties in sea level projections will require massive, interdisciplinary efforts that are not currently in place

  10. Processes affecting geochemistry and contaminant movement in the middle Claiborne aquifer of the Mississippi embayment aquifer system

    Science.gov (United States)

    Katz, Brian G.; Kingsbury, James A.; Welch, Heather L.; Tollett, Roland W.

    2012-01-01

    Groundwater chemistry and tracer-based age data were used to assess contaminant movement and geochemical processes in the middle Claiborne aquifer (MCA) of the Mississippi embayment aquifer system. Water samples were collected from 30 drinking-water wells (mostly domestic and public supply) and analyzed for nutrients, major ions, pesticides, volatile organic compounds (VOCs), and transient age tracers (chlorofluorocarbons, tritium and helium-3, and sulfur hexafluoride). Redox conditions are highly variable throughout the MCA. However, mostly oxic groundwater with low dissolved solids is more vulnerable to nitrate contamination in the outcrop areas east of the Mississippi River in Mississippi and west Tennessee than in mostly anoxic groundwater in downgradient areas in western parts of the study area. Groundwater in the outcrop area was relatively young (apparent age of less than 40 years) with significantly (p 50 m depth) indicated contaminant movement from shallow parts of the aquifer into deeper oxic zones. Given the persistence of nitrate in young oxic groundwater that was recharged several decades ago, and the lack of a confining unit, the downward movement of young contaminated water may result in higher nitrate concentrations over time in deeper parts of the aquifer containing older oxic water.

  11. Effect of selection and sequencing of representative wave conditions on process-based predictions of equilibrium embayed beach morphology

    Science.gov (United States)

    Daly, Christopher J.; Bryan, Karin R.; Gonzalez, Mauricio R.; Klein, Antonio H. F.; Winter, Christian

    2014-06-01

    In order to decrease the simulation time of morphodynamic models, often-complex wave climates are reduced to a few representative wave conditions (RWC). When applied to embayed beaches, a test of whether a reduced wave climate is representative or not is to see whether it can recreate the observed equilibrium (long-term averaged) bathymetry of the bay. In this study, the wave climate experienced at Milagro Beach, Tarragona, Spain was discretized into `average' and `extreme' RWCs. Process-based morphodynamic simulations were sequenced and merged based on `persistent' and `transient' forcing conditions, the results of which were used to estimate the equilibrium bathymetry of the bay. Results show that the effect of extreme wave events appeared to have less influence on the equilibrium of the bay compared to average conditions of longer overall duration. Additionally, the persistent seasonal variation of the wave climate produces pronounced beach rotation and tends to accumulate sediment at the extremities of the beach, rather than in the central sections. It is, therefore, important to account for directional variability and persistence in the selection and sequencing of representative wave conditions as is it essential for accurately balancing the effects beach rotation events.

  12. Shallow marine response to global climate change during the Paleocene-Eocene Thermal Maximum, Salisbury Embayment, USA

    Science.gov (United States)

    Self-Trail, Jean; Robinson, Marci M.; Bralower, Timothy J.; Sessa, Jocelyn A.; Hajek, Elizabeth A.; Kump, Lee R.; Trampush, Sheila M.; Willard, Debra A.; Edwards, Lucy E.; Powars, David S.; Wandless, Gregory A.

    2017-01-01

    The Paleocene-Eocene Thermal Maximum (PETM) was an interval of extreme warmth that caused disruption of marine and terrestrial ecosystems on a global scale. Here we examine the sediments, flora, and fauna from an expanded section at Mattawoman Creek-Billingsley Road (MCBR) in Maryland and explore the impact of warming at a nearshore shallow marine (30–100 m water depth) site in the Salisbury Embayment. Observations indicate that at the onset of the PETM, the site abruptly shifted from an open marine to prodelta setting with increased terrestrial and fresh water input. Changes in microfossil biota suggest stratification of the water column and low-oxygen bottom water conditions in the earliest Eocene. Formation of authigenic carbonate through microbial diagenesis produced an unusually large bulk carbon isotope shift, while the magnitude of the corresponding signal from benthic foraminifera is similar to that at other marine sites. This proves that the landward increase in the magnitude of the carbon isotope excursion measured in bulk sediment is not due to a near instantaneous release of 12C-enriched CO2. We conclude that the MCBR site records nearshore marine response to global climate change that can be used as an analog for modern coastal response to global warming.

  13. Shallow marine response to global climate change during the Paleocene-Eocene Thermal Maximum, Salisbury Embayment, USA

    Science.gov (United States)

    Self-Trail, Jean M.; Robinson, Marci M.; Bralower, Timothy J.; Sessa, Jocelyn A.; Hajek, Elizabeth A.; Kump, Lee R.; Trampush, Sheila M.; Willard, Debra A.; Edwards, Lucy E.; Powars, David S.; Wandless, Gregory A.

    2017-07-01

    The Paleocene-Eocene Thermal Maximum (PETM) was an interval of extreme warmth that caused disruption of marine and terrestrial ecosystems on a global scale. Here we examine the sediments, flora, and fauna from an expanded section at Mattawoman Creek-Billingsley Road (MCBR) in Maryland and explore the impact of warming at a nearshore shallow marine (30-100 m water depth) site in the Salisbury Embayment. Observations indicate that at the onset of the PETM, the site abruptly shifted from an open marine to prodelta setting with increased terrestrial and fresh water input. Changes in microfossil biota suggest stratification of the water column and low-oxygen bottom water conditions in the earliest Eocene. Formation of authigenic carbonate through microbial diagenesis produced an unusually large bulk carbon isotope shift, while the magnitude of the corresponding signal from benthic foraminifera is similar to that at other marine sites. This proves that the landward increase in the magnitude of the carbon isotope excursion measured in bulk sediment is not due to a near instantaneous release of 12C-enriched CO2. We conclude that the MCBR site records nearshore marine response to global climate change that can be used as an analog for modern coastal response to global warming.

  14. The Effects of Mississippi Embayment Sediments on Local Earthquake Tomography Models for the New Madrid Seismic Zone

    Science.gov (United States)

    Powell, C.; Withers, M.

    2008-12-01

    The effects of velocity and thickness variations in thick, unconsolidated Mississippi Embayment sediments on local earthquake tomography for the New Madrid seismic zone are investigated using normal station corrections, synthetic modeling, and application of a sediment correction based upon independent knowledge of sediment thickness and velocity structure. Synthetic modeling indicates that smearing from strong velocity perturbations in the unconsolidated sediments can influence the uppermost basement portion of the P wave velocity solution and can extend into deeper portions of the S wave velocity solution. However, there is little evidence for smearing due to velocity perturbations in the unconsolidated sediments in inversion results obtained using real arrival time data. The clustered distribution of hypocenters makes station corrections sensitive to velocity variations located deeper than the unconsolidated sediments and application of station corrections removes useful information about the basement from the inversion solution. The sediment correction also appears to remove useful information from the inversion solution but is an improvement for the P wave solution over removal of station corrections. There is no evidence that the sediment correction is removing smearing effects produced by velocity perturbations in the unconsolidated sediments. The unconsolidated sediments do not appear to be exerting a first order effect on local earthquake tomography solutions.

  15. Nutrient inputs through submarine groundwater discharge in an embayment: A radon investigation in Daya Bay, China

    Science.gov (United States)

    Wang, Xuejing; Li, Hailong; Yang, Jinzhong; Zheng, Chunmiao; Zhang, Yan; An, An; Zhang, Meng; Xiao, Kai

    2017-08-01

    Daya Bay, a semi-closed bay of the South China Sea, is famous for its aquaculture, agriculture and tourism. Although routine environmental investigations in the bay have been conducted since the early 1980s, evaluations of submarine groundwater discharge (SGD), an important process in exchange between groundwater and coastal seawater, and its environmental impacts have never been reported. In this study, naturally occurring radon isotope (222Rn) was measured continuously at two sites (north-west and middle-east sites) and used as a tracer to estimate SGD and associated nutrient inputs into the bay. The SGD rates estimated based on the 222Rn mass balance model were, on average, 28.2 cm/d at north-west site and 30.9 cm/d at middle-east site. The large SGD rate at middle-east site may be due to the large tidal amplitude and the sandy component with high permeability in sediments. The SGD-driven nutrient fluxes, which were calculated as the product of SGD flux and the difference of nutrient concentrations between coastal groundwater and seawater, were 3.28 × 105 mol/d for dissolved nitrates (NO3-N), 5.84 × 103 mol/d for dissolved inorganic phosphorous (DIP), and 8.97 × 105 mol/d for reactive silicate (Si). These nutrient inputs are comparable to or even higher than those supplied by local rivers. In addition, these SGD-driven nutrients have a nitrogen-phosphorous ratio as high as ∼43, which may significantly affect the ecology of coastal waters and lead to frequent occurrence of harmful algal blooms.

  16. Real-Time Teleguidance of a Non-Surgeon Crew Medical Officer Performing Orthopedic Surgery at the Amundsen-Scott South Pole Station During Winter-Over

    Science.gov (United States)

    Otto, Christian

    2010-01-01

    The Amundsen-Scott South Pole Research station located at the geographic South Pole, is the most isolated, permanently inhabited human outpost on Earth. Medical care is provided to station personnel by a non-surgeon crew medical officer (CMO). During the winter-over period from February to October, the station is isolated, with no incoming or outgoing flights due to severe weather conditions. In late June, four months after the station had closed for the austral winter, a 31 year old meteorologist suffered a complete rupture of his patellar tendon while sliding done an embankment. An evacuation was deemed to be too risky to aircrews due to the extreme cold and darkness. A panel of physicians from Massachusetts General Hospital, Johns Hopkins University and the University of Texas Medical Branch were able to assess the patient remotely via telemedicine and agreed that surgery was the only means to restore mobility and prevent long term disability. The lack of a surgical facility and a trained surgical team were overcome by conversion of the clinic treatment area, and intensive preparation of medical laypersons as surgical assistants. The non-surgeon CMO and CMO assistant at South Pole, were guided through the administration of spinal anesthetic, and the two-hour operative repair by medical consultants at Massachusetts General Hospital. Real-time video of the operative field, directions from the remote consultants and audio communication were provided by videoconferencing equipment, operative cameras, and high bandwidth satellite communications. In real-time, opening incision/exposure, tendon relocation, hemostatsis, and operative closure by the CMO was closely monitored and guided and by the remote consultants. The patient s subsequent physical rehabilitation over the ensuing months of isolation was also monitored remotely via telemedicine. This was the first time in South Pole s history that remote teleguidance had been used for surgery and represents a model for

  17. Morphodynamic rotation of an embayed sandy beach in a mud-dominated setting

    Science.gov (United States)

    Brunier, Guillaume; Anthony, Edward; Gardel, Antoine; Millet, Bertrand; Fleury, Jules; Dussouillez, Philippe

    2016-04-01

    The morphodynamics of beaches between bedrock headlands along the muddy French Guiana coast in South America are controlled by rotation induced by the alongshore migration of mud banks from the mouths of the Amazon River. As they migrate alongshore, these mud banks generate changes in shore-incident wave angles, resulting in reversals in longshore drift. A poor appreciation of the problems caused by this process has resulted in the past in damages to the highly urbanized sea-fronts on these beaches, including erosion and flooding. This work enhances our understanding of this rather unusual type of mud-induced rotation based on surveys of the 4 km-long Montjoly beach near Cayenne, in French Guiana, in the course of an approaching mud bank between October 2013 and October 2014. Our method was based on innovative high-resolution topographic surveys from airborne Structure-from-Motion (SfM) photogrammetry over the beach in October 2013, March 2014 and October 2014. We produced digital surface models (DSM) with a resolution of 10 cm/pixel and an accuracy less than 10 cm from RTK-GPS measurements. We further measured incident wave heights from pressure sensors and conducted a bathymetric survey of the nearshore zone in October 2014. We also modelled high-tide wave propagation over the bathymetry using the REF/DIF v2.5 model. The results show the transfer of sand from the northern part of beach to the south between October 2013 and March 2014. The October 2013 DSM shows a reflective beach in the north indicative of erosion, with a narrow 50 m-wide upper beach. The southern sector was smoother and up to 90 m-wide. Between October 2013 and March 2014, the beach rotated under the influence of a mud bank, with a 30-m retreat of the berm in the north and an advance of 40 m in the south. We quantified a loss of ≈66,000 m³ of sand in the north and a gain of ≈22,000 m³ in the south over this six-month period. The October 2014 DSM shows minor morphological changes, thus

  18. The Neogene molasse deposits of the Zagros Mountains in central Dezful Embayment: facies, sedimentary environments and controls

    Directory of Open Access Journals (Sweden)

    Ali Hossein Jalilian

    2016-03-01

    Full Text Available The upper part of Neogene sequence of the Zagros Mountains consists of a clastic succession which is identified as Aghajari and Bakhtyari formations. The sequence is an excellent example of synorogenic sedimentation or molasse deposited in northern portion of the Zagros foreland basin. Sedimentological analysis of an outcrop section representing Miocene-Pliocene sediments in central Dezful Embayment resulted in recognizing 9 lithofacies and 4 architectural elements. These lithofacies include conglometate (Gt, Gh, Gmm, sandstone (Sp, Sh, Sr, St and mudstone (Fm, Fl that were deposited in meandering stream, braided river and alluvial fan environments. Paleocurrent analysis of cross-beds, channels and asymmetric ripple marks indicate that these Neogene clastics were mainly drived from Cretaceous to Paleogene highlands in the Zagros Mountains on the north. This stratigraphic record is coarsening-upward and formed by a regressive depositional megacycle under arid climate. Facies and depositional history analysis show that sedimentation of the Zagros molasse was primarily controlled by base-level changes rather than catchment lithology or climate. The sedimentary record of this regressive megacycle reveales the base-level was constantly falling down on one hand and the provenance was uplifting on the other hand. Tectonic activities and Zagros Mountains rising in the Late Miocene resulted in deposition of fining-upward point-bar and floodplain sequences of the Aghajari Formation in low-gradient meandering streams. The Lahbari Member of the Aghajari Formation represents deposition in braided rivers that composed predominantly of flood-plain deposits in the Early Pliocene. Finally, the sedimentary cycle of the Zagros molasse deposits terminated with massive conglomerates of the Bakhtyari Formation deposited in large alluvial fans near the source area.

  19. Analysis on long-term variability of sea ice albedo and its relationship with sea ice concentration over Antarctica

    Science.gov (United States)

    Seo, Minji; Kim, Hyun-cheol; Seong, Noh-hun; Kwon, Chaeyoung; Kim, Honghee; Han, Kyung-Soo

    2016-10-01

    Sea ice is an important factor for understanding Antarctic climate change. Especially, annual change of sea ice shows different trend in Antarctica and Arctic. This different variation need to continuously observe the Polar Regions. Sea Ice Albedo (SIA) and Sea Ice Concentration (SIC) are an indicator of variation on sea ice. In addition, albedo is key parameter to understand the energy budget in Antarctica. This being so, it is important to analyze long-term variation of the two factors for observing of change of Antarctic environment. In this study, we analyzed long-term variability of SIC and SIA to understand the changes of sea ice over Antarctic and researched the relationship with two factors. We used the SIA data at The Satellite Application Facility on Climate Monitoring (CM SAF) and the SIC data provided by Ocean and Sea Ice Satellite Application Facility (OSI-SAF) from 1982 to 2009. The study period was selected to Antarctic summer season due to polar nights. We divided study periods into two terms, Nov-Dec(ND) and Jan-Feb(JF) in order to reflect the characteristics of sea ice area, which minimum extend occurred in September and maximum extend occurred in February. We analyzed the correlation between SIA and SIC. As a results, two variables have a strong positive correlation (each correlation coefficients are 0.91 in Nov-Dec and 0.90 in Jan-Feb). We performed time series analysis using linear regression to understand the spatial and temporal tendency of SIA and SIC. As a results, SIA and SIC have a same spatial trend such as Weddle sea and Ross sea sections show the positive trend and Bellingshausen Amundsen sea shows the negative trend of two factors. Moreover, annual SIA change rate is 0.26% 0.04% yr-1 over section where represent positive trend during two study periods. And annual SIA change rate is - 0.14 - 0.25 % yr-1 of in the other part where represent negative trend during two study periods.

  20. Fish assemblages associated with natural and anthropogenically-modified habitats in a marine embayment: comparison of baited videos and opera-house traps.

    Directory of Open Access Journals (Sweden)

    Corey B Wakefield

    Full Text Available Marine embayments and estuaries play an important role in the ecology and life history of many fish species. Cockburn Sound is one of a relative paucity of marine embayments on the west coast of Australia. Its sheltered waters and close proximity to a capital city have resulted in anthropogenic intrusion and extensive seascape modification. This study aimed to compare the sampling efficiencies of baited videos and fish traps in determining the relative abundance and diversity of temperate demersal fish species associated with naturally occurring (seagrass, limestone outcrops and soft sediment and modified (rockwall and dredge channel habitats in Cockburn Sound. Baited videos sampled a greater range of species in higher total and mean abundances than fish traps. This larger amount of data collected by baited videos allowed for greater discrimination of fish assemblages between habitats. The markedly higher diversity and abundances of fish associated with seagrass and limestone outcrops, and the fact that these habitats are very limited within Cockburn Sound, suggests they play an important role in the fish ecology of this embayment. Fish assemblages associated with modified habitats comprised a subset of species in lower abundances when compared to natural habitats with similar physical characteristics. This suggests modified habitats may not have provided the necessary resource requirements (e.g. shelter and/or diet for some species, resulting in alterations to the natural trophic structure and interspecific interactions. Baited videos provided a more efficient and non-extractive method for comparing fish assemblages and habitat associations of smaller bodied species and juveniles in a turbid environment.

  1. Connectivity of a large embayment and coastal fishery: spawning aggregations in one bay source local and broad-scale fishery replenishment.

    Science.gov (United States)

    Hamer, P A; Acevedo, S; Jenkins, G P; Newman, A

    2011-04-01

    Ichthyoplankton sampling and otolith chemistry were used to determine the importance of transient spawning aggregations of snapper Chrysophrys auratus (Sparidae) in a large embayment, Port Phillip Bay (PPB), Australia, as a source of local and broad-scale fishery replenishment. Ichthyoplankton sampling across five spawning seasons within PPB, across the narrow entrance to the bay and in adjacent coastal waters, indicated that although spawning may occur in coastal waters, the spawning aggregations within the bay were the primary source of larval recruitment to the bay. Otolith chemical signatures previously characterized for 0+ year C. auratus of two cohorts (2000 and 2001) were used as the baseline signatures to quantify the contribution that fish derived from reproduction in PPB make to fishery replenishment. Sampling of these cohorts over a 5 year period at various widely dispersed fishery regions, combined with maximum likelihood analyses of the chemistry of the 0+ year otolith portions of these older fish, indicated that C. auratus of 1 to 3+ years of age displayed both local residency and broad-scale emigration from PPB to populate coastal waters and an adjacent bay (Western Port). While the PPB fishery was consistently dominated (>70%) by locally derived fish irrespective of cohort or age, the contribution of fish that had originated from PPB to distant populations increased with age. At 4 to 5+ years of age, when C. auratus mature and fully recruit to the fishery, populations of both cohorts across the entire central and western Victorian fishery, including two major embayments and c. 800 km of coastal waters, were dominated (>70%) by fish that had originated from the spawning aggregations and nursery habitat within PPB. Dependence of this broadly dispersed fishery on replenishment from heavily targeted spawning aggregations within one embayment has significant implications for management and monitoring programmes.

  2. Improved Bathymetry Resolution in the Ross Sea from Aerogravity and Magnetics: Examples from Operation IceBridge.

    Science.gov (United States)

    Tinto, K. J.; Cochran, J. R.; Bell, R. E.; Charles, K.; Burton, B.

    2014-12-01

    The Ross Ice Shelf, located in the embayment between East and West Antarctica, is one of the largest underexplored patches of ocean on the planet. Sediment cores show that the Ross Ice Shelf can disintegrate during some interglacial periods. The conditions required for sudden collapse are not well constrained. A key to understanding the dynamics and long-term stability of the Ross Ice Shelf system is having high-resolution constraints on its boundary conditions, including sea floor bathymetry. The sea floor under the Ross Ice Shelf has developed in response to both the tectonic development of the West Antarctic Rift and the glacial signature of the waxing and waning Antarctic Ice Sheets. A mixture of fabrics and orientations in its bathymetry reflect this complex development. However, present oceanographic models of water circulation under the ice are based on low-resolution bathymetric maps drawn from stations spaced 55 km apart obtained during the RIGGS project in the 1970s. In contrast, most of the bathymetry of the world's oceans has been mapped to approximately 15 km resolution from satellite altimetry and much higher resolution from acoustic surveys. Improvement of Ross Ice Shelf bathymetry can be achieved from combined analysis and inversion of gravity and magnetic data acquired from airborne surveys over the Ross Ice Shelf. Survey lines flown in 2013 by Operation IceBridge, with the Sander Geophysics Ltd AIRGrav system over the central and northern Ross Embayment provide a tenfold increase, to 5 km, of the along track resolution of bathymetry. Newly resolved bathymetric highs and lows have amplitudes of up to 200 km. Combining the gravity and magnetic surveys also reveals the differing geology across the embayment. Results from these surveys, including comparison with ship-based bathymetry data from the Ross Sea, demonstrate the value of gravity and magnetic surveys for mapping the bathymetry of the Ross Ice Shelf and the need for more comprehensive

  3. Coral reefs in an urban embayment in Hawaii: a complex case history controlled by natural and anthropogenic stress

    Science.gov (United States)

    Grigg, R. W.

    1995-11-01

    The effects of natural and anthropogenic stress need to be separated before coral reef ecosystems can be effectively managed. In this paper, a 25 year case history of coral reefs in an urban embayment (Mamala Bay) off Honolulu, Hawaii is described and differences between natural and man-induced stress are distinguished. Mamala Bay is a 30 km long shallow coastal bay bordering the southern (leeward) shore of Oahu and the city of Honolulu in the Hawaiian Islands. During the last 25 years, this area has been hit by two magnitude 5 hurricane events (winds > 240 km/h) generating waves in excess of 7.5 m. Also during this period, two large sewer outfalls have discharged up to 90 million gallons per day (mgd) or (360 × 106 L/day) of point source pollution into the bay. Initially the discharge was raw sewage, but since 1977 it has received advanced primary treatment. Non-point source run-off from the Honolulu watershed also enters the bay on a daily basis. The results of the study show that discharge of raw sewage had a serious but highly localized impact on shallow (˜10 m) reef corals in the bay prior to 1977. After 1977, when treatment was upgraded to the advanced primary level and outfalls were extended to deep water (> 65 m), impacts to reef corals were no longer significant. No measurable effects of either point or non-point source pollution on coral calcification, growth, species composition, diversity or community structure related to pollution can now be detected. Conversely the effects of hurricane waves in 1982 and 1992 together caused major physical destruction to the reefs. In 1982, average coral cover of well-developed offshore reefs dropped from 60-75% to 5-15%. Only massive species in high relief areas survived. Today, recovery is occurring, and notwithstanding major future disturbance events, long-term biological processes should eventually return the coral ecosystems to a more mature successional stage. This case history illustrates the complex nature of

  4. Biomarker evidence for shallow water marine euxinia through the PTB in the Panthalassic Ocean (Peace River Basin Embayment, Canada)

    Science.gov (United States)

    Hays, L. E.; Beatty, T.; Henderson, C. M.; Summons, R. E.; Love, G. D.

    2007-12-01

    Protracted euxinic conditions in the late Paleozoic and early Mesozoic oceans may have been an important paleoenvironmental factor in the Permian-Triassic Boundary (PTB) extinction. Release of hydrogen sulfide during upwelling or transgressive events from such an ocean (Kump et al. 2005; Riccardi et al. 2006) may have been a driver of the extinction in both marine and terrestrial environments. Worldwide marine PTB sections show evidence for a stratified water column and the presence of sulfidic deep water, at least episodically (Isozaki 1997; Grice et al. 2005). Taxa that are particularly characteristic of such an environment are the green sulfur bacteria, or Chlorobiaceae. These anoxygenic phototrophic bacteria utilize sulfide as an electron donor for photosynthesis and live in modern stratified water columns where euxinia extends into the photic zone. Indeed, biomarkers derived from these organisms have been identified at a number of the PTB sections. The Peace River embayment in western Canada has been identified as a section that spans the PTB based on conodont biostratigraphy (Henderson 1997). Samples from five drill cores in this section provide new insight into the state of the Panthalassic Ocean during this time of unprecedented turnover in Earth's biota. Using standard biomarker protocols, we identified aromatic hydrocarbons that are diagentic products of the carotenoids isorenieratene and chlorobactene, which are diagnostic for the brown and green strains, respectively, of the Chlorobiaceae. The occurrence of chlorobactane is especially notable since the green-pigmented varieties of the Chlorobiaceae require higher light intensities than the brown-pigmented forms and, in modern environments where they have been found, occur between 13 and 30 m of the surface. This is the first time that chlorobactane has been reported from a PTB section and it suggests a particularly shallow chemocline periodically at this location. The δ13C values for the aryl

  5. Crustal structure beneath the Northern Mississippi Embayment from travel time inversion of vintage wide-angle seismic data

    Science.gov (United States)

    Guo, L.; Magnani, M.

    2012-12-01

    The northern Mississippi Embayment (ME) in the central US is located along the southern margin of Laurentia, a region that has been shaped by a long history of tectonic and magmatic events, including episodes of continental rifting, collision and amalgamation. In the ME these events have fundamentally altered the structure and composition of the continental lithosphere, resulting in the formation and failure of the Paleozoic Reelfoot Rift, and in the emplacement of the enigmatic mafic rift pillow at lower crustal and upper mantle depths beneath the Reelfoot Rift. Because of the spatial correlation between the present, historical and prehistorical seismicity in the New Madrid seismic zone and the mafic rift pillow, it has been proposed that this magmatic feature plays a key role in localizing strain in the Central US. Emerging evidence, however, shows that Quaternary deformation in the ME is not restricted to the New Madrid seismic zone, but encompasses a region beyond the presently seismogenic area, perhaps suggesting that the mafic rift pillow extends beyond its previously detected location. To test this hypothesis and to better constrain the lateral extent, dimension, and velocity structure of the mafic rift pillow in lower crust and upper mantle beneath the ME, we perform a travel time tomographic inversion using recent modeling codes on two vintage wide-angle seismic datasets available in the region. The data were acquired by the USGS in 1980 and 1991, and are the only seismic wide-angle crustal data constraining the geometry of the rift pillow. The 1980 USGS seismic refraction investigation consisted of a total of 34 900-1800 kg shots gathered in 9 locations and recorded by 100 portable seismographs along a series of profiles targeting the structure of the Reelfoot Rift north of Memphis, Tennessee. The 1991 USGS survey acquired a N-S 400 km-long seismic profile from Memphis, Tennessee to St. Louis, Missouri, and included 3 680-2260 kg shots recorded by ~200

  6. Regional Changes in the Sea Ice Cover and Ice Production in the Antarctic

    Science.gov (United States)

    Comiso, Josefino C.

    2011-01-01

    Coastal polynyas around the Antarctic continent have been regarded as sea ice factories because of high ice production rates in these regions. The observation of a positive trend in the extent of Antarctic sea ice during the satellite era has been intriguing in light of the observed rapid decline of the ice extent in the Arctic. The results of analysis of the time series of passive microwave data indicate large regional variability with the trends being strongly positive in the Ross Sea, strongly negative in the Bellingshausen/Amundsen Seas and close to zero in the other regions. The atmospheric circulation in the Antarctic is controlled mainly by the Southern Annular Mode (SAM) and the marginal ice zone around the continent shows an alternating pattern of advance and retreat suggesting the presence of a propagating wave (called Antarctic Circumpolar Wave) around the circumpolar region. The results of analysis of the passive microwave data suggest that the positive trend in the Antarctic sea ice cover could be caused primarily by enhanced ice production in the Ross Sea that may be associated with more persistent and larger coastal polynyas in the region. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate-of-increase in the net ice export of about 30,000 km2 per year. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 km3/year, which is almost identical, within error bars, to our estimate of the trend in ice production. In addition to the possibility of changes in SAM, modeling studies have also indicated that the ozone hole may have a role in that it causes the deepening of the lows in the western Antarctic region thereby causing strong winds to occur offthe Ross-ice shelf.

  7. Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

    Science.gov (United States)

    Halberstadt, Anna Ruth W.; Simkins, Lauren M.; Greenwood, Sarah L.; Anderson, John B.

    2016-05-01

    Studying the history of ice-sheet behaviour in the Ross Sea, Antarctica's largest drainage basin can improve our understanding of patterns and controls on marine-based ice-sheet dynamics and provide constraints for numerical ice-sheet models. Newly collected high-resolution multibeam bathymetry data, combined with two decades of legacy multibeam and seismic data, are used to map glacial landforms and reconstruct palaeo ice-sheet drainage. During the Last Glacial Maximum, grounded ice reached the continental shelf edge in the eastern but not western Ross Sea. Recessional geomorphic features in the western Ross Sea indicate virtually continuous back-stepping of the ice-sheet grounding line. In the eastern Ross Sea, well-preserved linear features and a lack of small-scale recessional landforms signify rapid lift-off of grounded ice from the bed. Physiography exerted a first-order control on regional ice behaviour, while sea floor geology played an important subsidiary role. Previously published deglacial scenarios for Ross Sea are based on low-spatial-resolution marine data or terrestrial observations; however, this study uses high-resolution basin-wide geomorphology to constrain grounding-line retreat on the continental shelf. Our analysis of retreat patterns suggests that (1) retreat from the western Ross Sea was complex due to strong physiographic controls on ice-sheet drainage; (2) retreat was asynchronous across the Ross Sea and between troughs; (3) the eastern Ross Sea largely deglaciated prior to the western Ross Sea following the formation of a large grounding-line embayment over Whales Deep; and (4) our glacial geomorphic reconstruction converges with recent numerical models that call for significant and complex East Antarctic ice sheet and West Antarctic ice sheet contributions to the ice flow in the Ross Sea.

  8. Sea Legs

    Science.gov (United States)

    Macdonald, Kenneth C.

    Forty-foot, storm-swept seas, Spitzbergen polar bears roaming vast expanses of Arctic ice, furtive exchanges of forbidden manuscripts in Cold War Moscow, the New York city fashion scene, diving in mini-subs to the sea floor hot srings, life with the astronauts, romance and heartbreak, and invading the last bastions of male exclusivity: all are present in this fast-moving, non-fiction account of one woman' fascinating adventures in the world of marine geology and oceanography.

  9. Reconstructing the contribution of the Weddell Sea sector, Antarctica, to sea level rise since the last glacial maximum, using numerical modelling constrained by field evidence.

    Science.gov (United States)

    Le Brocq, A.; Bentley, M.; Hubbard, A.; Fogwill, C.; Sugden, D.

    2008-12-01

    A numerical ice sheet model constrained by recent field evidence is employed to reconstruct the Last Glacial Maximum (LGM) ice sheet in the Weddell Sea Embayment (WSE). Previous modelling attempts have predicted an extensive grounding line advance (to the continental shelf break) in the WSE, leading to a large equivalent sea level contribution for the sector. The sector has therefore been considered as a potential source for a period of rapid sea level rise (MWP1a, 20 m rise in ~500 years). Recent field evidence suggests that the elevation change in the Ellsworth mountains at the LGM is lower than previously thought (~400 m). The numerical model applied in this paper suggests that a 400 m thicker ice sheet at the LGM does not support such an extensive grounding line advance. A range of ice sheet surfaces, resulting from different grounding line locations, lead to an equivalent sea level estimate of 1 - 3 m for this sector. It is therefore unlikely that the sector made a significant contribution to sea level rise since the LGM, and in particular to MWP1a. The reduced ice sheet size also has implications for the correction of GRACE data, from which Antarctic mass balance calculations have been derived.

  10. Deglacial floods in the Beaufort Sea

    Science.gov (United States)

    Keigwin, L. D.; Driscoll, N. W.

    2014-12-01

    During summer 2013 USCGC Healy cruise 1302 surveyed and cored between Barrow, AK and the mouth of Amundsen Gulf, far to the east in the Beaufort Sea. Holocene deposition rates on the continental slope are high in the eastern Chukchi Sea and are lower farther east where deglacial sediments dominate. This is evident in CHIRP seismic data that trace two groups of reflectors as the sub-bottom depth between them increases. On the slope, at ~700 m w.d. near the mouth of the Mackenzie River, a pair of piston cores make a composite sequence 17 m long. The lower 4 m are sandy and capped by a maximum in magnetic susceptibility (ms) and a prominent reflector. N. pachyderma is too rare in this interval for 14C dates, but the d18-O of this species is as low as late Holocene. Above the reflector, counts of IRD are low, d18-O continues low, and the sediment is an acoustically transparent 7 m thick unit. The deepest date is 12.8 conv. 14C kyr at 13 m, and 3 overlying dates indicate the transparent unit accumulated at 8 m/14C kyr. The top of this unit is marked by the upper reflector that is in detail a triplet that corresponds to triple peaks in ms, grainsize, and IRD abundance. Between the two oldest sub-peaks of this reflector, d18-O reaches minimum values of ~1‰, or about 0.5‰ lower than late Holocene. In contrast to the deeper interval, this event is only 0.5 m thick and is dated to 11,050 conv. 14C kyr. Following this event, d18-O increases abruptly and then gradually decreases within the Holocene, more like a typical isotope stratigraphy. Overall, 9 dates indicate a gradual down-core increase in sedimentation rates from 9 cm/kyr in the late Holocene to the extreme of the deeper transparent unit with no age reversals. Using the modern Beaufort Sea Delta R (DR; 436 yrs), our oldest date calibrates to 13.8 ka, a little too old to be the cause of the Younger Dryas. However, the combined seismic, isotope, and sedimentological data suggest that at least the older transparent

  11. A joint local, regional and teleseismic tomography study and shear wave splitting beneath the Mississippi Embayment and New Madrid seismic zone

    Science.gov (United States)

    Nyamwandha, Cecilia Anyango

    Part 1: We have determined detailed crust and upper mantle 3-D P wave and S wave velocity models to a depth of 400 km for the Mississippi Embayment (ME) and the New Madrid seismic zone (NMSZ). This study incorporates data from three networks; the New Madrid Seismic Network (CNMSN) operated by the Center for Earthquake Research and Information (CERI), the Earthscope Transportable Array (TA), and the FlexArray (FA) Northern Embayment Lithospheric Experiment (NELE) project stations to aid in constructing the most detailed velocity images for the NMSZ to date. For the crust we observe a separation of velocity highs from velocity lows along the axis of the Mississippi Valley Graben (MVG). For the upper mantle, we image a significant low velocity anomaly of ˜ -3% to -5 % at depths of 100 - 250 km. A high velocity anomaly of ˜ +3% to +4% is observed at depths of 80 - 160 km and it occurs along the sides and top of the low velocity anomaly. The Vp and Vs solutions in the upper mantle show a remarkable similarity both in shape and anomaly magnitude. We propose that the observed low velocity features in the upper mantle are as a result of various tectonic activities in the area, which could result in: 1) Rejuvenated/primitive mantle, 2) Elevated temperatures, and 3) Increased fluid content. A combination of elevated temperatures and increased fluid content reduce P wave velocity (Vp) whereas the three effects combined significantly reduce S wave velocity (Vs). The high velocity anomalies observed are associated with mafic rocks emplaced in the lithosphere beneath the ME during initial rifting in the early Paleozoic and/or remnants of the depleted, lower portion of the lithosphere. Part 2: Using teleseismic SKS phases recorded with the Northern Embayment Lithosphere Experiment (NELE), and the USArray Transportable Array (TA), we apply the SplitLab processing environment to measure shear wave splitting within and outside the Mississippi Embayment (ME) for the period 2011

  12. Carbon sources in the Beaufort Sea revealed by molecular lipid biomarkers and compound specific isotope analysis

    Science.gov (United States)

    Tolosa, I.; Fiorini, S.; Gasser, B.; Martín, J.; Miquel, J. C.

    2012-10-01

    Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids) and compound specific isotope analysis of suspended particulate organic matter (SPM) and surface sediments of the Mackenzie Shelf and slope (Southeast Beaufort Sea, Arctic Ocean), were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the sedimentary organic matter (OM). Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and 80%) with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60-75%) whereas those from the slope contained the highest proportion of fossil (40%) and C3 terrestrial plant material (10%). Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC) found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the sediments accounted for 30-40% of the total carbon in the inner shelf sediments, 17% in the outer shelf and Amundsen Gulf and up to 25% in the slope sediments.

  13. Paleo ice flow and subglacial meltwater dynamics in Pine Island Bay, West Antarctica

    Directory of Open Access Journals (Sweden)

    F. O. Nitsche

    2013-02-01

    Full Text Available Increasing evidence for an elaborate subglacial drainage network underneath modern Antarctic ice sheets suggests that basal meltwater has an important influence on ice stream flow. Swath bathymetry surveys from previously glaciated continental margins display morphological features indicative of subglacial meltwater flow in inner shelf areas of some paleo ice stream troughs. Over the last few years several expeditions to the eastern Amundsen Sea embayment (West Antarctica have investigated the paleo ice streams that extended from the Pine Island and Thwaites glaciers. A compilation of high-resolution swath bathymetry data from inner Pine Island Bay reveals details of a rough seabed topography including several deep channels that connect a series of basins. This complex basin and channel network is indicative of meltwater flow beneath the paleo-Pine Island and Thwaites ice streams, along with substantial subglacial water inflow from the east. This meltwater could have enhanced ice flow over the rough bedrock topography. Meltwater features diminish with the onset of linear features north of the basins. Similar features have previously been observed in several other areas, including the Dotson-Getz Trough (western Amundsen Sea embayment and Marguerite Bay (SW Antarctic Peninsula, suggesting that these features may be widespread around the Antarctic margin and that subglacial meltwater drainage played a major role in past ice-sheet dynamics.

  14. Last Glacial Maximum sea surface temperature and sea-ice extent in the Pacific sector of the Southern Ocean

    Science.gov (United States)

    Benz, Verena; Esper, Oliver; Gersonde, Rainer; Lamy, Frank; Tiedemann, Ralf

    2016-08-01

    Sea surface temperatures and sea-ice extent are most critical variables to evaluate the Southern Ocean paleoceanographic evolution in relation to the development of the global carbon cycle, atmospheric CO2 and ocean-atmosphere circulation. Here we present diatom transfer function-based summer sea surface temperature (SSST) and winter sea-ice (WSI) estimates from the Pacific sector of the Southern Ocean to bridge a gap in information that has to date hampered a well-established reconstruction of the last glacial Southern Ocean at circum-Antarctic scale. We studied the Last Glacial Maximum (LGM) at the EPILOG time slice (19,000-23,000 calendar years before present) in 17 cores and consolidated our LGM picture of the Pacific sector taking into account published data from its warmer regions. Our data display a distinct east-west differentiation with a rather stable WSI edge north of the Pacific-Antarctic Ridge in the Ross Sea sector and a more variable WSI extent over the Amundsen Abyssal Plain. The zone of maximum cooling (>4 K) during the LGM is in the present Subantarctic Zone and bounded to its south by the 4 °C isotherm. The isotherm is in the SSST range prevailing at the modern Antarctic Polar Front, representing a circum-Antarctic feature, and marks the northern edge of the glacial Antarctic Circumpolar Current (ACC). The northward deflection of colder than modern surface waters along the South American continent led to a significant cooling of the glacial Humboldt Current surface waters (4-8 K), which affected the temperature regimes as far north as tropical latitudes. The glacial reduction of ACC temperatures may also have resulted in significant cooling in the Atlantic and Indian Southern Ocean, thus enhancing thermal differentiation of the Southern Ocean and Antarctic continental cooling. The comparison with numerical temperature and sea-ice simulations yields discrepancies, especially concerning the estimates of the sea-ice fields, but some simulations

  15. Influence of the Southern Annular Mode on the sea ice-ocean system: the role of the thermal and mechanical forcing

    Directory of Open Access Journals (Sweden)

    W. Lefebvre

    2005-06-01

    Full Text Available The global sea ice-ocean model ORCA2-LIM is used to investigate the impact of the thermal and mechanical forcing associated to the Southern Annular Mode (SAM on the Antarctic sea ice-ocean system. To do so, the model is driven by idealized forcings based on regressions of the wind stress and the air temperature to SAM. The wind-stress component strongly affects the overall patterns of the ocean circulation with a northward surface drift, a downwelling at about 45° S and an upwelling in the vicinity of the Antarctic continent when SAM is positive. On the other hand, the thermal forcing has a negligible effect on the ocean currents. For sea ice, both the wind-stress (mechanical and the air temperature (thermal components have a significant impact. The mechanical part induces a decrease of the sea ice thickness close to the continent and a sharp decrease of the mean sea ice thickness in the Weddell sector. In general, the sea ice area also diminishes, with a maximum decrease in the Weddell Sea. On the contrary, the thermal part tends to increase the ice concentration in all sectors except in the Weddell Sea, where the ice area shrinks. This thermal effect is the strongest in autumn and in winter due to the larger temperature differences associated with SAM during these seasons. The sum of the thermal and mechaninal effects gives a dipole response of sea ice to the SAM, with a decrease of the ice area in the Weddell Sea and around the Antarctic Peninsula and an increase in the Ross and Amundsen Seas during high SAM years. This is in good agreement with the observed response of the ice cover to SAM.

  16. Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula

    Science.gov (United States)

    Hurst, Thomas P.

    2016-05-01

    Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller-Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30 m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.

  17. Sea Ice

    Science.gov (United States)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  18. Sea level change

    Digital Repository Service at National Institute of Oceanography (India)

    Church, J.A.; Clark, P.U.; Cazenave, A.; Gregory, J.M.; Jevrejeva, S.; Levermann, A.; Merrifield, M.A.; Milne, G.A.; Nerem, R.S.; Nunn, P.D.; Payne, A.J.; Pfeffer, W.T.; Stammer, D.; Unnikrishnan, A.S.

    This chapter considers changes in global mean sea level, regional sea level, sea level extremes, and waves. Confidence in projections of global mean sea level rise has increased since the Fourth Assessment Report (AR4) because of the improved...

  19. Modeling circulation patterns induced by spatial cross-shore wind variability in a small-size coastal embayment

    Science.gov (United States)

    Cerralbo, Pablo; Espino, Manuel; Grifoll, Manel

    2016-08-01

    This contribution shows the importance of the cross-shore spatial wind variability in the water circulation in a small-sized micro-tidal bay. The hydrodynamic wind response at Alfacs Bay (Ebro River delta, NW Mediterranean Sea) is investigated with a numerical model (ROMS) supported by in situ observations. The wind variability observed in meteorological measurements is characterized with meteorological model (WRF) outputs. From the hydrodynamic simulations of the bay, the water circulation response is affected by the cross-shore wind variability, leading to water current structures not observed in the homogeneous-wind case. If the wind heterogeneity response is considered, the water exchange in the longitudinal direction increases significantly, reducing the water exchange time by around 20%. Wind resolutions half the size of the bay (in our case around 9 km) inhibit cross-shore wind variability, which significantly affects the resultant circulation pattern. The characteristic response is also investigated using idealized test cases. These results show how the wind curl contributes to the hydrodynamic response in shallow areas and promotes the exchange between the bay and the open sea. Negative wind curl is related to the formation of an anti-cyclonic gyre at the bay's mouth. Our results highlight the importance of considering appropriate wind resolution even in small-scale domains (such as bays or harbors) to characterize the hydrodynamics, with relevant implications in the water exchange time and the consequent water quality and ecological parameters.

  20. Status of marine biodiversity of the China seas.

    Science.gov (United States)

    Liu, J Y

    2013-01-01

    China's seas cover nearly 5 million square kilometers extending from the tropical to the temperate climate zones and bordering on 32,000 km of coastline, including islands. Comprehensive systematic study of the marine biodiversity within this region began in the early 1950s with the establishment of the Qingdao Marine Biological Laboratory of the Chinese Academy of Sciences. Since that time scientists have carried out intensive multidisciplinary research on marine life in the China seas and have recorded 22,629 species belonging to 46 phyla. The marine flora and fauna of the China seas are characterized by high biodiversity, including tropical and subtropical elements of the Indo-West Pacific warm-water fauna in the South and East China seas, and temperate elements of North Pacific temperate fauna mainly in the Yellow Sea. The southern South China Sea fauna is characterized by typical tropical elements paralleled with the Philippine-New Guinea-Indonesia Coral triangle typical tropical faunal center. This paper summarizes advances in studies of marine biodiversity in China's seas and discusses current research mainly on characteristics and changes in marine biodiversity, including the monitoring, assessment, and conservation of endangered species and particularly the strengthening of effective management. Studies of (1) a tidal flat in a semi-enclosed embayment, (2) the impact of global climate change on a cold-water ecosystem, (3) coral reefs of Hainan Island and Xisha-Nansha atolls, (4) mangrove forests of the South China Sea, (5) a threatened seagrass field, and (6) an example of stock enhancement practices of the Chinese shrimp fishery are briefly introduced. Besides the overexploitation of living resources (more than 12.4 million tons yielded in 2007), the major threat to the biodiversity of the China seas is environmental deterioration (pollution, coastal construction), particularly in the brackish waters of estuarine environments, which are characterized by

  1. Status of marine biodiversity of the China seas.

    Directory of Open Access Journals (Sweden)

    J Y Liu

    Full Text Available China's seas cover nearly 5 million square kilometers extending from the tropical to the temperate climate zones and bordering on 32,000 km of coastline, including islands. Comprehensive systematic study of the marine biodiversity within this region began in the early 1950s with the establishment of the Qingdao Marine Biological Laboratory of the Chinese Academy of Sciences. Since that time scientists have carried out intensive multidisciplinary research on marine life in the China seas and have recorded 22,629 species belonging to 46 phyla. The marine flora and fauna of the China seas are characterized by high biodiversity, including tropical and subtropical elements of the Indo-West Pacific warm-water fauna in the South and East China seas, and temperate elements of North Pacific temperate fauna mainly in the Yellow Sea. The southern South China Sea fauna is characterized by typical tropical elements paralleled with the Philippine-New Guinea-Indonesia Coral triangle typical tropical faunal center. This paper summarizes advances in studies of marine biodiversity in China's seas and discusses current research mainly on characteristics and changes in marine biodiversity, including the monitoring, assessment, and conservation of endangered species and particularly the strengthening of effective management. Studies of (1 a tidal flat in a semi-enclosed embayment, (2 the impact of global climate change on a cold-water ecosystem, (3 coral reefs of Hainan Island and Xisha-Nansha atolls, (4 mangrove forests of the South China Sea, (5 a threatened seagrass field, and (6 an example of stock enhancement practices of the Chinese shrimp fishery are briefly introduced. Besides the overexploitation of living resources (more than 12.4 million tons yielded in 2007, the major threat to the biodiversity of the China seas is environmental deterioration (pollution, coastal construction, particularly in the brackish waters of estuarine environments, which are

  2. A comparison of fish communities of subtidal seagrass beds and sandy seabeds in 13 marine embayments of a Caribbean island, based on species, families, size distribution and functional groups

    Science.gov (United States)

    Nagelkerken, I.; van der Velde, G.

    2004-08-01

    Differences in fish community structure between different estuaries, lagoons and bays can be very large, and generalisations are complicated by the use of a wide variety of sampling methods. In the present study, fish communities of subtidal seagrass beds and sandy seabeds in 13 marine embayments of a single Caribbean island were therefore sampled using a uniform method. The objective of the study was to determine whether the seagrass and sandy seabed habitats of various embayments are characterised by typical fish assemblages which differ in terms of taxa (species, families), size classes (life stages) and functional groups (ecological species groups, feeding time and diet). This was linked to the hypothesis that differences in fish assemblages between habitats in different embayments are larger at taxonomic levels than at the level of functional groups. A second objective was to determine the most useful discriminating features between the two habitat types. The above hypothesis was rejected, since differences in fish assemblages from different seagrass and sandy seabed sites did not increase from functional to taxonomic level, but from size class to diet/species to family/feeding time to ecological species group. However, the seagrass and sandy seabed habitats could each be characterised by typical fish assemblages which differed in taxonomical and functional group composition, irrespective of differences in environmental and biotic variables between the embayments in which these habitats were situated. The two habitat types could be best characterised on the basis of fish family, ecological species group, feeding time and size distribution. Seagrass beds mainly harboured nocturnally active nursery species (Haemulidae, Lutjanidae, etc.), whose relative abundance was related to vegetation (mainly seagrass) cover. Sandy seabeds mainly harboured diurnally active bay species (Gerreidae, etc.) whose relative abundance was related to cover of bare sand. Similarities

  3. Modelling survival and connectivity of Mnemiopsis leidyi in the southern North Sea and Scheldt estuaries

    Directory of Open Access Journals (Sweden)

    J. van der Molen

    2014-06-01

    Full Text Available Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming – however this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here.

  4. Modelling survival and connectivity of Mnemiopsis leidyi in the southern North Sea and Scheldt estuaries

    Science.gov (United States)

    van der Molen, J.; van Beek, J.; Augustine, S.; Vansteenbrugge, L.; van Walraven, L.; Langenberg, V.; van der Veer, H. W.; Hostens, K.; Pitois, S.; Robbens, J.

    2014-06-01

    Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming - however this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here.

  5. A multivariate assessment of the coral ecosystem health of two embayments on the lee of the island of Hawai'i

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, Michael L. [Marine Science Department, University of Hawai' i at Hilo, Hilo, HI 96720 (United States)], E-mail: mparsons@fgcu.edu; Walsh, William J. [Division of Aquatic Resources, Department of Land and Natural Resources, Kailua-Kona, HI 96740 (United States); Settlemier, Chelsie J.; White, Darla J.; Ballauer, Josh M.; Ayotte, Paula M.; Osada, Kara M. [Marine Science Department, University of Hawai' i at Hilo, Hilo, HI 96720 (United States); Carman, Brent [Division of Aquatic Resources, Department of Land and Natural Resources, Kailua-Kona, HI 96740 (United States)

    2008-06-15

    Four coral-dominated coastal sites within two embayments (Kealakekua Bay and Honokohau Bay) on the lee of the island of Hawai'i were studied to assess evidence of anthropogenic impacts in these relatively pristine locales. Nutrient-loading parameters were analyzed in relation to benthic composition data. Statistically, there were significant positive relationships between nitrate + nitrite, silicate, and ammonium with the abundance of macroalgae, coralline algae, and dead coral, and between {delta}{sup 15}N and dead coral abundance. The north outside site of Kealakekua Bay and the south outside site of Honokohau Bay appear to be most impacted by nutrient-loading factors in each bay, respectively. Comparisons with past nutrient data indicate that nutrient inputs have increased to the two bays, and that early impacts of these increased loadings are evident. It is predicted that at current nutrient-loading rates, the north sites of Kealakekua Bay and the south sites of Honokohau Bay will exhibit evidence of further degradation in future years.

  6. Fecal pollution in coastal marine sediments from a semi-enclosed deep embayment subjected to anthropogenic activities: an issue to be considered in environmental quality management frameworks development.

    Science.gov (United States)

    González-Fernández, D; Garrido-Pérez, M C; Nebot-Sanz, E; Sales-Márquez, D

    2010-12-01

    Sewage discharge is a major source of pollution in marine environments. Urban wastewaters can directly enter marine environments carrying pathogen organisms, organic loads, and nutrients. Because marine sediments can act as the ultimate fate of a wide range of pollutants, environmental quality assessment in this compartment can help to identify pollution problems in coastal areas. In the present study, characterization of surficial marine sediments allowed assessment of fecal pollution in a semi-enclosed deep embayment that is subjected to anthropogenic activities. Physicochemical parameters and fecal indicators presented a great spatial heterogeneity. Fecal coliform and Clostridium perfringens showed accumulation in an extensive area, not only in proximity to sewage discharge points, but also in sediments at 100 meters depth. Results included herein demonstrated that, in coastal areas, urban wastewater discharge can affect the whole ecosystem through accumulation of fecal matter in bottom sediments. Application of multivariate techniques provided useful information with applicability for management of coastal areas in such complex systems. Environmental implications of wastewater discharge in coastal areas indicate the need to implement and include sediment quality control strategies in legislative frameworks.

  7. Water-quality, water-level, and discharge data associated with the Mississippi embayment agricultural chemical-transport study, 2006-2008

    Science.gov (United States)

    Dalton, Melinda S.; Rose, Claire E.; Coupe, Richard H.

    2010-01-01

    In 2006, the Agricultural Chemicals: Sources, Transport and Fate study team (Agricultural Chemicals Team, ACT) of the U.S. Geological Survey National Water-Quality Assessment Program began a study in northwestern Mississippi to evaluate the influence of surface-water recharge on the occurrence of agriculturally related nutrients and pesticides in the Mississippi River Valley alluvial aquifer. The ACT study was composed in the Bogue Phalia Basin, an indicator watershed within the National Water-Quality Assessment Program Mississippi Embayment Study Unit and utilized several small, subbasins within the Bogue Phalia to evaluate surface and groundwater interaction and chemical transport in the Basin. Data collected as part of this ACT study include water-quality data from routine and incident-driven water samples evaluated for major ions, nutrients, organic carbon, physical properties, and commonly used pesticides in the area; discharge, gage height and water-level data for surface-water sites, the shallow alluvial aquifer, and hyporheic zone; additionally, agricultural data and detailed management activities were reported by land managers for farms within two subbasins of the Bogue Phalia Basin—Tommie Bayou at Pace, MS, and an unnamed tributary to Clear Creek near Napanee, MS.

  8. Mammals of the Sea.

    Science.gov (United States)

    Naturescope, 1986

    1986-01-01

    Presents information on sea mammals, including definitions and characteristics of cetaceans, pinnipeds, and sirenians. Contains descriptions of the teaching activities "Whale Music,""Draw A Whale to Scale,""Adopt a Sea Mammal," and "Sea Mammal Sleuths." (TW)

  9. Mammals of the Sea.

    Science.gov (United States)

    Naturescope, 1986

    1986-01-01

    Presents information on sea mammals, including definitions and characteristics of cetaceans, pinnipeds, and sirenians. Contains descriptions of the teaching activities "Whale Music,""Draw A Whale to Scale,""Adopt a Sea Mammal," and "Sea Mammal Sleuths." (TW)

  10. Developments in Airborne Oceanography and Air-Sea Interaction

    Science.gov (United States)

    Melville, W. K.

    2014-12-01

    One of the earliest ocean-related flights was that of Amundsen to be first across the North Pole and Arctic from Svalbard to Alaska in the airship Norge in 1926. Twenty five years later Cox & Munk flew a B-17G "Flying Fortress" bomber over Hawaiian waters measuring sea surface slope statistics from photographs of sun glitter and wind speed from a yacht. The value of Cox & Munk's "airborne oceanography" became apparent another twenty five years later with the short-lived Seasat microwave remote-sensing mission, since interpretation of the Seasat data in geophysical variables required scattering theories that relied on their data. The universal acceptance of remote sensing in oceanography began in 1992 with the launch of, and successful analysis of sea surface height data from, the Topex/Poseidon radar altimeter. With that and the development of more realistic coupled atmosphere-ocean models it became apparent that our understanding of weather and climate variability in both the atmosphere and the ocean depends crucially on our ability to measure processes in boundary layers spanning the interface. Ten years ago UNOLS formed the Scientific Committee for Oceanographic Aircraft Research (SCOAR) "...to improve access to research aircraft facilities for ocean sciences"; an attempt to make access to aircraft as easy as access to research vessels. SCOAR emphasized then that "Aircraft are ideal for both fast-response investigations and routine, long-term measurements, and they naturally combine atmospheric measurements with oceanographic measurements on similar temporal and spatial scales." Since then developments in GPS positioning and miniaturization have made scientific measurements possible from smaller and smaller platforms, including the transition from manned to unmanned aerial vehicles (UAVs). Furthermore, ship-launched and recovered UAVs have demonstrated how they can enhance the capabilities and reach of the research vessels, "projecting" research and science

  11. Lower satellite-gravimetry estimates of Antarctic sea-level contribution.

    Science.gov (United States)

    King, Matt A; Bingham, Rory J; Moore, Phil; Whitehouse, Pippa L; Bentley, Michael J; Milne, Glenn A

    2012-11-22

    Recent estimates of Antarctica's present-day rate of ice-mass contribution to changes in sea level range from 31 gigatonnes a year (Gt yr(-1); ref. 1) to 246 Gt yr(-1) (ref. 2), a range that cannot be reconciled within formal errors. Time-varying rates of mass loss contribute to this, but substantial technique-specific systematic errors also exist. In particular, estimates of secular ice-mass change derived from Gravity Recovery and Climate Experiment (GRACE) satellite data are dominated by significant uncertainty in the accuracy of models of mass change due to glacial isostatic adjustment (GIA). Here we adopt a new model of GIA, developed from geological constraints, which produces GIA rates systematically lower than those of previous models, and an improved fit to independent uplift data. After applying the model to 99 months (from August 2002 to December 2010) of GRACE data, we estimate a continent-wide ice-mass change of -69 ± 18 Gt yr(-1) (+0.19 ± 0.05 mm yr(-1) sea-level equivalent). This is about a third to a half of the most recently published GRACE estimates, which cover a similar time period but are based on older GIA models. Plausible GIA model uncertainties, and errors relating to removing longitudinal GRACE artefacts ('destriping'), confine our estimate to the range -126 Gt yr(-1) to -29 Gt yr(-1) (0.08-0.35 mm yr(-1) sea-level equivalent). We resolve 26 independent drainage basins and find that Antarctic mass loss, and its acceleration, is concentrated in basins along the Amundsen Sea coast. Outside this region, we find that West Antarctica is nearly in balance and that East Antarctica is gaining substantial mass.

  12. Airborne radar surveys of snow depth over Antarctic sea ice during Operation IceBridge

    Science.gov (United States)

    Panzer, B.; Gomez-Garcia, D.; Leuschen, C.; Paden, J. D.; Gogineni, P. S.

    2012-12-01

    Over the last decade, multiple satellite-based laser and radar altimeters, optimized for polar observations, have been launched with one of the major objectives being the determination of global sea ice thickness and distribution [5, 6]. Estimation of sea-ice thickness from these altimeters relies on freeboard measurements and the presence of snow cover on sea ice affects this estimate. Current means of estimating the snow depth rely on daily precipitation products and/or data from passive microwave sensors [2, 7]. Even a small uncertainty in the snow depth leads to a large uncertainty in the sea-ice thickness estimate. To improve the accuracy of the sea-ice thickness estimates and provide validation for measurements from satellite-based sensors, the Center for Remote Sensing of Ice Sheets deploys the Snow Radar as a part of NASA Operation IceBridge. The Snow Radar is an ultra-wideband, frequency-modulated, continuous-wave radar capable of resolving snow depth on sea ice from 5 cm to more than 2 meters from long-range, airborne platforms [4]. This paper will discuss the algorithm used to directly extract snow depth estimates exclusively using the Snow Radar data set by tracking both the air-snow and snow-ice interfaces. Prior work in this regard used data from a laser altimeter for tracking the air-snow interface or worked under the assumption that the return from the snow-ice interface was greater than that from the air-snow interface due to a larger dielectric contrast, which is not true for thick or higher loss snow cover [1, 3]. This paper will also present snow depth estimates from Snow Radar data during the NASA Operation IceBridge 2010-2011 Antarctic campaigns. In 2010, three sea ice flights were flown, two in the Weddell Sea and one in the Amundsen and Bellingshausen Seas. All three flight lines were repeated in 2011, allowing an annual comparison of snow depth. In 2011, a repeat pass of an earlier flight in the Weddell Sea was flown, allowing for a

  13. Three-dimensional visualization maps of suspended-sediment concentrations during placement of dredged material in 21st Avenue West Channel Embayment, Duluth-Superior Harbor, Duluth, Minnesota, 2015

    Science.gov (United States)

    Groten, Joel T.; Ellison, Christopher A.; Mahoney, Mollie H.

    2016-06-30

    Excess sediment in rivers and estuaries poses serious environmental and economic challenges. The U.S. Army Corps of Engineers (USACE) routinely dredges sediment in Federal navigation channels to maintain commercial shipping operations. The USACE initiated a 3-year pilot project in 2013 to use navigation channel dredged material to aid in restoration of shoreline habitat in the 21st Avenue West Channel Embayment of the Duluth-Superior Harbor. Placing dredged material in the 21st Avenue West Channel Embayment supports the restoration of shallow bay aquatic habitat aiding in the delisting of the St. Louis River Estuary Area of Concern.The U.S. Geological Survey, in cooperation with the USACE, collected turbidity and suspended-sediment concentrations (SSCs) in 2014 and 2015 to measure the horizontal and vertical distribution of SSCs during placement operations of dredged materials. These data were collected to help the USACE evaluate the use of several best management practices, including various dredge material placement techniques and a silt curtain, to mitigate the dispersion of suspended sediment.Three-dimensional visualization maps are a valuable tool for assessing the spatial displacement of SSCs. Data collection was designed to coincide with four dredged placement configurations that included periods with and without a silt curtain as well as before and after placement of dredged materials. Approximately 230 SSC samples and corresponding turbidity values collected in 2014 and 2015 were used to develop a simple linear regression model between SSC and turbidity. Using the simple linear regression model, SSCs were estimated for approximately 3,000 turbidity values at approximately 100 sampling sites in the 21st Avenue West Channel Embayment of the Duluth-Superior Harbor. The estimated SSCs served as input for development of 12 three-dimensional visualization maps.

  14. About the consistency between Envisat and CryoSat-2 radar freeboard retrieval over Antarctic sea ice

    Directory of Open Access Journals (Sweden)

    S. Schwegmann

    2015-09-01

    Full Text Available Knowledge about Antarctic sea-ice volume and its changes over the past decades has been sparse due to the lack of systematic sea-ice thickness measurements in this remote area. Recently, first attempts have been made to develop a sea-ice thickness product over the Southern Ocean from space-borne radar altimetry and results look promising. Today, more than 20 years of radar altimeter data are potentially available for such products. However, data come from different sources, and the characteristics of individual sensors differ. Hence, it is important to study the consistency between single sensors in order to develop long and consistent time series over the potentially available measurement period. Here, the consistency between freeboard measurements of the Radar Altimeter 2 on-board Envisat and freeboard measurements from the Synthetic-Aperture Interferometric Radar Altimeter on-board CryoSat-2 is tested for their overlap period in 2011. Results indicate that mean and modal values are comparable over the sea-ice growth season (May–October and partly also beyond. In general, Envisat data shows higher freeboards in the seasonal ice zone while CryoSat-2 freeboards are higher in the perennial ice zone and near the coasts. This has consequences for the agreement in individual sectors of the Southern Ocean, where one or the other ice class may dominate. Nevertheless, over the growth season, mean freeboard for the entire (regional separated Southern Ocean differs generally by not more than 2 cm (5 cm, except for the Amundsen/Bellingshausen Sea between Envisat and CryoSat-2, and the differences between modal freeboard lie generally within ±10 cm and often even below.

  15. White sea radioactivity assessment

    Energy Technology Data Exchange (ETDEWEB)

    Aliev, R.A. [Lomonosov Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics]|[Lomonosov Moscow State Univ. (Russian Federation). Chemistry Dept.]|[Russian Academy of Sciences, Moscow (Russian Federation). Shirshov Inst. of Oceanology; Kalmykov, S.N.; Lisitzin, A.P. [Lomonosov Moscow State Univ. (Russian Federation). Chemistry Dept.

    2004-07-01

    The aim of the present work is to estimate potential sources and chronology of pollution of the White Sea (Russia) by artificial radionuclides. White Sea is semi-closed water body connected with Barents Sea by a narrow strait. Thus, pollution of White Sea may be caused by highly polluted Barents waters and river (mainly Northern Dvina) run-off. This is the first detailed investigation of radioactivity of White Sea sediment records. (orig.)

  16. Coastal response to simultaneous mid-Holocene climate and sea-level changes: Lessons from ancient Egypt

    Science.gov (United States)

    Hein, C. J.; FitzGerald, D. M.; Milne, G. A.; Bard, K. A.; Fattovich, R.

    2011-12-01

    Coastal evolution during the Holocene has been driven by complex interactions between changes in sea level, climate, and sedimentation processes. Along the Egyptian Red Sea coast, a post-glacial marine transgression drowned a series of wadi channels, flooding their lower reaches to create shallow lagoons. Archeological investigations at one such site, Mersa / Wadi Gawasis, have uncovered the existence of an ancient Egyptian harbor along a carbonate / conglomerate terrace located 600 m landward of the modern shoreline; this discovery documented the world's earliest (3.5 - 4.0 ka) archaeological evidence of long-distance seafaring. This site is interpreted to have been a harbor servicing trade routes along the African Red Sea coast. Sedimentological, malacological, chorological, and foraminiferal analyses indicate that this harbor was located within a low energy, 6 - 8 m deep, tidal embayment that once extended ~1 km inland of the modern shore. A buried coral-beach rock platform and tidal flat sediments are found ubiquitously along the periphery of the paleo-bay and at elevations of up to 1 m above modern mean sea level. Wave-cut notches and erosional terraces observed at 1.1 - 1.8 m above modern sea level along the modern shoreline provide additional evidence of a higher-than-present stand of sea-level during the mid-Holocene. Sea-level predictions generated using a site-specific isostatic model for the northern the Red Sea confirm the presence of 0.5 - 2 m highstand at 5 ka. Reconstructions indicate that the bay at Mersa / Wadi Gawasis reached its maximum surface area prior to the highstand. Preliminary closure was driven by sediment inputs from the adjacent wadi, enhanced by the wetter climate of the African Humid Period, combined with a slowing rate of sea-level rise, thus demonstrating the dominance of sedimentary processes during this period. Following the highstand, slowly falling sea level coincidental with climatic aridization allowed for the establishment

  17. Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

    Science.gov (United States)

    van der Molen, J.; van Beek, J.; Augustine, S.; Vansteenbrugge, L.; van Walraven, L.; Langenberg, V.; van der Veer, H. W.; Hostens, K.; Pitois, S.; Robbens, J.

    2015-06-01

    Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here.

  18. Changes of floodplain morphology by water mills: Legacy sediments stored behind mill dams as archive and source for pollution - Examples from the Wurm River, Lower Rhine Embayment, Germany

    Science.gov (United States)

    Buchty-Lemke, Michael; Frings, Roy; Hagemann, Lukas; Lehmkuhl, Frank; Maaß, Anna-Lisa; Schwarzbauer, Jan

    2016-04-01

    The Wurm River (Lower Rhine Embayment, Germany) is a small stream in a low mountain area near the Dutch-German border that has seen a lot of anthropogenic changes of its morphology since medieval times. Among other influencing factors, water mills, in particular, had an early impact on the sediment dynamics and created sediment traps. Several knickpoints in the long profile may represent the legacy of mill damming - or founded mill building at these spots. The knickpoints may also represent the aftermath of the colliery history. A study site in the upper reaches of the Wurm River features erosion terraces, incised following the demise of a mill dam in the early 20th century. The mill pond most likely collected sediment and additives e.g. used in agricultural and industrial processes. These legacy sediments from behind former mill dams provide information about anthropogenic pollution, particularly for the era of industrialization in the vicinity of the old industrial area of the city of Aachen. Along with the demise of the mill dam and the increased incision tendency, the sediments are also a secondary source for pollution in case of remobilization of contaminated sediments. Two major research questions are addressed. A) Which individual hydrological and geomorphological processes, both upstream and downstream, triggered the incision and the construction of the erosion terraces, which are preserved in the mill pond sediments? Is either the demised mill dam, or subsidence effects, or a combination of both the determining factor? B) Which contaminants are retained in the sediments? Is there a detectable point source for the pollutants or is it a mixture of diffuse anthropogenic (industry, agriculture, traffic, wastewater) and natural origin? To tackle these questions, sedimentological data are combined with geomorphological mapping and evaluation of historical data. A soil profile provides insight into the architecture of the floodplain, which is built of riverbed

  19. Arctic data compilation and appraisal. Vol. 10, Beaufort Sea: Biological oceanography - whales 1848 to 1983

    Energy Technology Data Exchange (ETDEWEB)

    Norton, P.; Smiley, B.D.; de March, L.

    1987-01-01

    This data report is an inventory of measurements and observations of white whales, bowhead whales, gray whales, harbour porpoises, narwhal, and killer whales in the Beaufort Sea and Amundsen Gulf. Measurements most commonly reported concern numbers, identification, movements, morphometrics, age behaviour, food, and reproduction. Organization within this inventory is by data set (measurements and observations made by one group of people, for a particular purpose, generally within one year). In all, 143 data sets were inventoried for the 1848 to 1983 period. Times and locations of sampling efforts are listed in tables and also are shown on computer-drawn maps. Sampling methodology and intensity, whale measurements and observations obtained by species, and concurrent bio logical, physical, and chemical measurements are described in the tables. A five-level rating system, based on sampling methodolgy, is outlined and has been applied to each measurement in each data set as a rough indication of the data's reliability. Data sets are indexed according to geographic coverage, study methods, species, measurements and observations made by category, and published references. The form, location, and availability of original data is given if know. 74 refs 115 figs 3 tabs

  20. Enhancements to the Mississippi Embayment Regional Aquifer Study (MERAS) groundwater-flow model and simulations of sustainable water-level scenarios

    Science.gov (United States)

    Clark, Brian R.; Westerman, Drew A.; Fugitt, D. Todd

    2013-01-01

    Arkansas continues to be one of the largest users of groundwater in the Nation. As such, long-term planning and management are essential to ensure continued availability of groundwater and surface water for years to come. The Mississippi Embayment Regional Aquifer Study (MERAS) model was developed previously as a tool to evaluate groundwater availability within the Mississippi embayment, which encompasses much of eastern Arkansas where the majority of groundwater is used. The Arkansas Water Plan is being updated for the first time since 1990 and serves as the State’s primary, comprehensive water-resources planning and guidance document. The MERAS model was selected as the best available tool for evaluation of specific water-use pumping scenarios that are currently being considered by the State of Arkansas. The model, developed as part of the U.S. Geological Survey Groundwater Resources Program’s assessment of the Nation’s groundwater availability, is proving to be invaluable to the State as it works toward development of a sustained yield pumping strategy. One aspect of this investigation was to evaluate multiple methods to improve the match of observed to simulated groundwater levels within the Mississippi River Valley alluvial and middle Claiborne (Sparta) aquifers in the MERAS model. Five primary methods were evaluated: (1) explicit simulation of evapotranspiration (ET), (2) upgrade of the Multi-Node Well (MNW2) Package, (3) geometry improvement within the Streamflow Routing (SFR) Package, (4) parameter estimation of select aquifer properties with pilot points, and (5) modification of water-use estimates. For the planning purposes of the Arkansas Water Plan, three scenarios were developed to evaluate potential future conditions: (1) simulation of previously optimized pumping values within the Mississippi River Valley alluvial and the middle Claiborne aquifers, (2) simulated prolonged effects of pumping at average recent (2000–5) rates, and (3) simulation

  1. 7 CFR 1437.310 - Sea grass and sea oats.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value...

  2. Sea Turtle Interaction Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sea Turtle Interaction Report is a report sent out in pdf format to authorized individuals that summarizes sea turtle interactions in the longline fishery. The...

  3. Sea Turtle Interaction Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sea Turtle Interaction Report is a report sent out in pdf format to authorized individuals that summarizes sea turtle interactions in the longline fishery. The...

  4. Sea Lion Diet Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — California sea lions pup and breed at four of the nine Channel Islands in southern California. Since 1981, SWFSC MMTD has been conducting a diet study of sea lions...

  5. All That Unplowed Sea

    Science.gov (United States)

    MOSAIC, 1975

    1975-01-01

    Hunting and gathering at sea may fast be approaching their productive limits. Aquaculture - farming at sea - linked to conservation represents the sea's promise. If the system works, it might prove to be the key to supplying large amounts of food and fresh water at no cost in nonrenewable energy resources. (BT)

  6. The Caspian Sea Environment

    Science.gov (United States)

    Kostianoy, Andrey; Kosarev, A.

    The systematic description of the knowledge accumulated on the physical oceanography, marine chemistry and pollution, and marine biology of the Caspian Sea forms the basis of this book. It presents the principal characteristic features of the environmental conditions of the sea and their changes in the second half of the 20th century. At present, the principal problems of the Caspian Sea are related to the interannual sea level changes and their forecast and to the estimation of the intensity of the chemical pollution of the sea and its impact upon the biota.

  7. Close-range airborne photogrammetry: an effective tool for high-resolution sandy beach morphometric surveys. Examples from embayed beaches in French Guyana.

    Science.gov (United States)

    Brunier, Guillaume; Fleury, Jules; Anthony, Edward; Gardel, Antoine; Dussouillez, Philippe

    2015-04-01

    Photogrammetric techniques are at a turning point in their history with the development of new algorithms, such as SIFT (Lowe, 1999) for automatic camera alignment and point cloud densification (Furukawa, 2010) integrated in user-friendly end-products. These innovations facilitate the utilization of this technique to study objects with low to mild morphological contrasts at low cost and by non-specialists. It is now possible to produce high-resolution 3D morphometric models, and derived products such as Digital Surface Models (DSM) and Orthophotographs. We conducted three photogrammetric experiments on the embayed beach of Montjoly (4 km long, 100-200 m wide) in Cayenne, French Guyana, in order to quantify morphological changes. The beach is affected by rotation induced by westward migration of mud banks from the Amazon that generate spatio-temporal changes in wave refraction and incident wave angles. The current rotation involves massive erosion of the northern part of the beach (50 m retreat between October 2013 and March 2014) and deposition in the southern sector (50 m advance). We acquired subvertical aerial photographs from a microlight aircraft using a full frame DSLR sensor with a 50 mm lens synchronized with an onboard DGPS, and flew alongshore at low elevation (900 ft). The flight plan included several parallel flight axes with a 50 m interband distance. Meanwhile on the ground, we placed around 30 square targets of 40 cm width georeferenced by RTK-DGPS with centimetre accuracy. These targets served in producing the georeferenced output 3D model. Third, we measured the topography of random points and cross-shore profiles to validate our results and assess the process accuracy. We produced the model and its derived products with user-friendly Agisoft Photoscan© software. We obtained three morphometric models realized in October 2013, March 2014 and October 2014 covering the entire beach. These models were produced at a resolution of 10 cm per pixel and

  8. Close-range airborne Structure-from-Motion Photogrammetry for high-resolution beach morphometric surveys: Examples from an embayed rotating beach

    Science.gov (United States)

    Brunier, Guillaume; Fleury, Jules; Anthony, Edward J.; Gardel, Antoine; Dussouillez, Philippe

    2016-05-01

    The field of photogrammetry has seen significant new developments essentially related to the emergence of new computer-based applications that have fostered the growth of the workflow technique called Structure-from-Motion (SfM). Low-cost, user-friendly SfM photogrammetry offers interesting new perspectives in coastal and other fields of geomorphology requiring high-resolution topographic data. The technique enables the construction of topographic products such as digital surface models (DSMs) and orthophotographs, and combines the advantages of the reproducibility of GPS surveys and the high density and accuracy of airborne LiDAR, but at very advantageous cost compared to the latter. Three SfM-based photogrammetric experiments were conducted on the embayed beach of Montjoly in Cayenne, French Guiana, between October 2013 and 2014, in order to map morphological changes and quantify sediment budgets. The beach is affected by a process of rotation induced by the alongshore migration of mud banks from the mouths of the Amazon River that generate spatial and temporal changes in wave refraction and incident wave angles, thus generating the reversals in longshore drift that characterise this process. Sub-vertical aerial photographs of the beach were acquired from a microlight aircraft that flew alongshore at low elevation (275 m). The flight plan included several parallel flight axes with an overlap of 85% between pictures in the lengthwise direction and 50% between paths. Targets of 40 × 40 cm, georeferenced by RTK-DGPS, were placed on the beach, spaced 100 m apart. These targets served in optimizing the model and in producing georeferenced 3D products. RTK-GPS measurements of random points and cross-shore profiles were used to validate the photogrammetry results and assess their accuracy. We produced dense point clouds with 150 to 200 points/m², from which we generated DSMs and orthophotos with respective resolutions of 10 cm and 5 cm. Compared to the GPS control

  9. SEA and planning

    DEFF Research Database (Denmark)

    Stoeglehner, G.; Brown, A.L.; Kørnøv, Lone

    2009-01-01

    As the field of strategic environmental assessment (SEA) has matured, the focus has moved from the development of legislation, guidelines and methodologies towards improving the effectiveness of SEA. Measuring and of course achieving effectiveness is both complex and challenging. This paper...... suggests that SEA professionals need to consider 'democratic effectiveness' as well as 'environmental effectiveness' in both 'direct' and 'indirect' outputs. The effectiveness of SEA depends critically on the context within which SEA legislation and guidelines are understood and implemented......, and the relationship of the SEA to the planning activity itself. This paper focuses on the influence that planners have in these implementation processes, postulating the hypothesis that these are key players in achieving effectiveness in SEA. Based upon implementation theory and empirical experience, the paper...

  10. Baltic Sea: Radionuclides

    DEFF Research Database (Denmark)

    Nielsen, Sven Poul; Lüning, Maria; Ilus, Erkki

    2011-01-01

    about 14%. For 90Sr in the Baltic Sea, input from atmospheric fallout from nuclear weapons tests has contributed about 81%, while the contribution from Chernobyl fallout was about 13%. Cesium-137 is the main indicator of Baltic seawater with respect to anthropogenic radioactivity. The highest....... Radioactivity inputs into the Baltic Sea from nuclear reprocessing plants in Western Europe have become of minor importance due to significant reduction of discharges in recent years. In terms of input of 137Cs into the Baltic Sea, Chernobyl fallout has contributed about 82% and nuclear weapons test fallout...... 137Cs values due to their higher concentration factors (CFs). The larger 137Cs values of pike were observed at the coast of the Bothnian Sea. The Baltic Sea is the regional sea in the world with the highest concentrations of 137Cs. The Baltic Sea ranks third in the world with respect to 90Sr...

  11. Baltic Sea: Radionuclides

    DEFF Research Database (Denmark)

    Nielsen, Sven Poul; Lüning, Maria; Ilus, Erkki

    2010-01-01

    about 14%. For 90Sr in the Baltic Sea, input from atmospheric fallout from nuclear weapons tests has contributed about 81%, while the contribution from Chernobyl fallout was about 13%. Cesium-137 is the main indicator of Baltic seawater with respect to anthropogenic radioactivity. The highest....... Radioactivity inputs into the Baltic Sea from nuclear reprocessing plants in Western Europe have become of minor importance due to significant reduction of discharges in recent years. In terms of input of 137Cs into the Baltic Sea, Chernobyl fallout has contributed about 82% and nuclear weapons test fallout...... 137Cs values due to their higher concentration factors (CFs). The larger 137Cs values of pike were observed at the coast of the Bothnian Sea. The Baltic Sea is the regional sea in the world with the highest concentrations of 137Cs. The Baltic Sea ranks third in the world with respect to 90Sr...

  12. Sea piracy and law of the sea

    OpenAIRE

    Hanif, Muhammad Tahir

    2010-01-01

    As the sea become world’s largest source to trade between the nations during the last few decades. Of course there are lots of problems in this regards when we are using the sea on such a large scale. The problem of piracy is most dangerous problems, among the all problems of the sea at the same time. Nations are trying to control this crime individually and collectively but the problem is still on its peak. Lots of international and national laws and conventions are held in this ...

  13. Continuous and discrete measurements of atmospheric methane from an ice core from Roosevelt Island, East Ross Sea, Antarctica

    Science.gov (United States)

    Blunier, T.; Simonsen, M. F.; Brook, E.; Lee, J.; Vallelonga, P. T.; Bertler, N. A. N.

    2014-12-01

    A new ice core from Roosevelt Island was drilled for the Roosevelt Island Climate Evolution (RICE) project to establish the history of deglaciation of the Ross Sea. Evidence of glacial retreat in the Ross Sea Embayment shows that deglaciation happened in several stages of rapid collapse and persisted well after the melting of the Northern Hemisphere ice sheets was complete. The drill location on a small island surrounded by sea ice makes dating the core a challenge. We present a timescale for Roosevelt Island using mixing ratios of methane in air preserved within the ice core measured continuously with a Picarro laser spectrometer as well as in high-resolution with gas chromatography (GC). Discrete data from GC analysis over the top 400m of core replicate both the magnitude and variations from other high-resolution ice core records from WAIS Divide, Law Dome, GISP2 and NEEM S1. Both the continuous and discrete methane records of the RICE core were matched to these established records and provide an accurate and consistent depth-age relationship for the past 3.6kyr. The deeper part of the core was measured continuously in July 2014. First inspection of the data suggests that the oldest section of the core reaches into the previous interglacial (Eemian). We will present preliminary evaluated continuous methane data for the deeper part of the core together with a first time scale for the Roosevelt Island ice core.

  14. Salish Sea Genetics - Salish Sea genetic inventory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Salish Sea comprises most of the Puget Sound water area. Marine species are generally assemblages of discrete populations occupying various ecological niches....

  15. Summer Arctic sea fog

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Synchronous or quasi-synchronous sea-land-air observations were conducted using advanced sea ice, atmospheric and marine instruments during China' s First Arctic Expedition. Based on the Precious data from the expedition, it was found that in the Arctic Ocean, most part of which is covered with ice or is mixed with ice, various kinds of sea fog formed such as advection fog, radiation fog and vapor fog. Each kind has its own characteristic and mechanics of creation. In the southern part of the Arctic Ocean, due to the sufficient warm and wet flow there, it is favorable for advection fog to form,which is dense and lasts a long time. On ice cap or vast floating ice, due to the strong radiation cooling effect, stable radiating fog is likely to form. In floating ice area there forms vapor fog with the appearance of masses of vapor from a boiling pot, which is different from short-lasting land fog. The study indicates that the reason why there are many kinds of sea fog form in the Arctic Ocean is because of the complicated cushion and the consequent sea-air interaction caused by the sea ice distribution and its unique physical characteristics. Sea fog is the atmospheric phenomenon of sea-air heat exchange. Especially, due to the high albedo of ice and snow surface, it is diffcult to absorb great amount of solar radiation during the polar days. Besides, ice is a poor conductor of heat; it blocks the sea-air heat exchange.The sea-air exchange is active in floating ice area where the ice is broken. The sea sends heat to the atmosphere in form of latent heat; vapor fog is a way of sea-air heat exchange influencing the climate and an indicator of the extent of the exchange. The study also indicates that the sea also transports heat to the atmosphere in form of sensible heat when vapor fog occurs.

  16. Variability and Anomalous Trends in the Global Sea Ice Cover

    Science.gov (United States)

    Comiso, Josefino C.

    2012-01-01

    The advent of satellite data came fortuitously at a time when the global sea ice cover has been changing rapidly and new techniques are needed to accurately assess the true state and characteristics of the global sea ice cover. The extent of the sea ice in the Northern Hemisphere has been declining by about -4% per decade for the period 1979 to 2011 but for the period from 1996 to 2010, the rate of decline became even more negative at -8% per decade, indicating an acceleration in the decline. More intriguing is the drastically declining perennial sea ice area, which is the ice that survives the summer melt and observed to be retreating at the rate of -14% per decade during the 1979 to 2012 period. Although a slight recovery occurred in the last three years from an abrupt decline in 2007, the perennial ice extent was almost as low as in 2007 in 2011. The multiyear ice, which is the thick component of the perennial ice and regarded as the mainstay of the Arctic sea ice cover is declining at an even higher rate of -19% per decade. The more rapid decline of the extent of this thicker ice type means that the volume of the ice is also declining making the survival of the Arctic ice in summer highly questionable. The slight recovery in 2008, 2009 and 2010 for the perennial ice in summer was likely associated with an apparent cycle in the time series with a period of about 8 years. Results of analysis of concurrent MODIS and AMSR-E data in summer also provide some evidence of more extensive summer melt and meltponding in 2007 and 2011 than in other years. Meanwhile, the Antarctic sea ice cover, as observed by the same set of satellite data, is showing an unexpected and counter intuitive increase of about 1 % per decade over the same period. Although a strong decline in ice extent is apparent in the Bellingshausen/ Amundsen Seas region, such decline is more than compensated by increases in the extent of the sea ice cover in the Ross Sea region. The results of analysis of

  17. Assessment of sediment quality in Avicennia marina-dominated embayments of Sydney Estuary: the potential use of pneumatophores (aerial roots) as a bio-indicator of trace metal contamination.

    Science.gov (United States)

    Nath, Bibhash; Birch, Gavin; Chaudhuri, Punarbasu

    2014-02-15

    Currently, coastal intertidal environments are under stress from increased contaminant loads due to urbanization and other anthropogenic disturbances. Mangrove habitats are abundant in tropical and sub-topical intertidal zones and frequently act as a metal bio-filter in estuarine systems. Mangrove reforestation is often considered as one of the management options to protect estuarine-marine habitats. The main objective of the present investigation was to assess the bio-indicator potential of Avicennia marina by determining heavy metal concentrations in pneumatophore (aerial root) tissues and ambient sediments from Sydney Estuary (Australia). We collected mangrove sediments and pneumatophores in fifteen locations covering five major embayments of the estuary for a detailed biogeochemical investigation. Metal concentrations in sediment were mostly above Australian interim sediment quality guidelines (ISQG)-Low and in few instances above ISQG-High values. Enrichment factors (EFs >6, especially of Cu, Pb and Zn) suggest "very severe" modification of sediment in Sydney Estuary in all but one embayment which was mainly due to rapid changes in land use in connection with urbanization. High bio-concentration factors (BCFs) were observed for Cu and Ni in comparison with other metals (i.e., As, Cd, Co, Cr, Pb and Zn). A strong, positive relationship between metals in sediments and pneumatophores suggests potential use of these tissues as a bio-indicator of estuarine contamination and that metals are entering the biotic environment. The study further highlights a positive role of mangroves in sequestering metals from sediments and the water column and thus protecting estuarine environments from pollution.

  18. Arctic Sea Level Reconstruction

    DEFF Research Database (Denmark)

    Svendsen, Peter Limkilde

    Reconstruction of historical Arctic sea level is very difficult due to the limited coverage and quality of tide gauge and altimetry data in the area. This thesis addresses many of these issues, and discusses strategies to help achieve a stable and plausible reconstruction of Arctic sea level from...... 1950 to today.The primary record of historical sea level, on the order of several decades to a few centuries, is tide gauges. Tide gauge records from around the world are collected in the Permanent Service for Mean Sea Level (PSMSL) database, and includes data along the Arctic coasts. A reasonable...... amount of data is available along the Norwegian and Russian coasts since 1950, and most published research on Arctic sea level extends cautiously from these areas. Very little tide gauge data is available elsewhere in the Arctic, and records of a length of several decades,as generally recommended for sea...

  19. South China Sea Challenge

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China's attempts to solve disputes with ASEAN over the South China Sea help regional peace China's marine economy and security are currently faced with new challenges, requiring careful handling, especially in disputes with ASEAN countries and in promoting common development of the South China Sea. The outcome of how this is dealt with could undoubtedly pave the way for solutions to other oceanic disputes. The South China Sea is located south of

  20. Dilemmas in SEA application

    DEFF Research Database (Denmark)

    Lyhne, Ivar

    Dilemmas in SEA Application: The DK Energy SectorIvar Lyhne - lyhne@plan.aau.dk. Based on three years of collaborative research, this paper outlines dilemmas in the application of SEA in the strategic development of the Danish energy sector. The dilemmas are based on concrete examples from practice...... the Danish energy sector) are starting to get it right. Lessons for SEA implementation in similar contexts are proposed....

  1. Pelagic sea snakes dehydrate at sea

    Science.gov (United States)

    Lillywhite, Harvey B.; Sheehy, Coleman M.; Brischoux, François; Grech, Alana

    2014-01-01

    Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis (Pelamis) platurus, which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans. PMID:24648228

  2. Pelagic sea snakes dehydrate at sea.

    Science.gov (United States)

    Lillywhite, Harvey B; Sheehy, Coleman M; Brischoux, François; Grech, Alana

    2014-05-07

    Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis (Pelamis) platurus, which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans.

  3. Simulating reef response to sea-level rise at Lizard Island: A geospatial approach

    Science.gov (United States)

    Hamylton, S. M.; Leon, J. X.; Saunders, M. I.; Woodroffe, C. D.

    2014-10-01

    Sea-level rise will result in changes in water depth over coral reefs, which will influence reef platform growth as a result of carbonate production and accretion. This study simulates the pattern of reef response on the reefs around Lizard Island in the northern Great Barrier Reef. Two sea-level rise scenarios are considered to capture the range of likely projections: 0.5 m and 1.2 m above 1990 levels by 2100. Reef topography has been established through extensive bathymetric profiling, together with available data, including LiDAR, single beam bathymetry, multibeam swath bathymetry, LADS and digitised chart data. The reef benthic cover around Lizard Island has been classified using a high resolution WorldView-2 satellite image, which is calibrated and validated against a ground referencing dataset of 364 underwater video records of the reef benthic character. Accretion rates are parameterised using published hydrochemical measurements taken in-situ and rules are applied using Boolean logic to incorporate geomorphological transitions associated with different depth ranges, such as recolonisation of the reef flat when it becomes inundated as sea level rises. Simulations indicate a variable platform response to the different sea-level rise scenarios. For the 0.5 m rise, the shallower reef flats are gradually colonised by corals, enabling this active geomorphological zone to keep up with the lower rate of rise while the other sand dominated areas get progressively deeper. In the 1.2 m scenario, a similar pattern is evident for the first 30 years of rise, beyond which the whole reef platform begins to slowly drown. To provide insight on reef response to sea-level rise in other areas, simulation results of four different reef settings are discussed and compared at the southeast reef flat (barrier reef), Coconut Beach (fringing reef), Watson's Bay (leeward bay with coral patches) and Mangrove Beach (sheltered lagoonal embayment). The reef sites appear to accrete upwards

  4. Sea surface temperatures and salinities from platforms in the Barents Sea, Sea of Japan, North Atlantic Ocean, Philippine Sea, Red Sea, and the South China Sea (Nan Hai) from 1896-1950 (NODC Accession 0000506)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface temperatures and salinities were collected in the Barents Sea, Sea of Japan, North Atlantic Ocean, Philippine Sea, Red Sea, and South China Sea (Nan Hai)...

  5. Somalia ... From the Sea

    Science.gov (United States)

    2009-07-01

    from the Sea, p. 7. 65. Robert D. Heinl, Jr., “Inchon, 1950,” in As- sault from the Sea: Essays on the History of Amphibious Warfare, ed. Merrill L...Mohamed Haji. Historical Dictionary of Somalia. New ed. Lanham, Md.: Scare- crow , 2003. Natsios, Andrew S. U.S. Foreign Policy and the Four Horsemen of

  6. SEA in Southern Africa

    CSIR Research Space (South Africa)

    Audouin, M

    2011-01-01

    Full Text Available in a number of them. Despite these trends, however, the opportunities that SEA can offer to facilitate sustainable development are not being realized. In this chapter, the authors describe the emergence of SEA in the post-colonial, democratic context...

  7. Oceanography of marginal seas

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    dioxide in intermediate layers falls from approx. 1000 mu atm in the southern end to approx. 500 mu atm in the northern Red Sea. Temperature in Atlantis II deep and brine level in Discovery deep in the Red Sea seem to be increasing in recent years...

  8. Dilemmas in SEA application

    DEFF Research Database (Denmark)

    Lyhne, Ivar

    Dilemmas in SEA Application: The DK Energy SectorIvar Lyhne - lyhne@plan.aau.dk. Based on three years of collaborative research, this paper outlines dilemmas in the application of SEA in the strategic development of the Danish energy sector. The dilemmas are based on concrete examples from practice...... in the implementation of SEA in the sector, and they concern, e.g., strategic choices in transmission network development and ministerial choices on location of energy production units. The paper outlines the roots of the dilemmas as well as their implications for timing and content of SEA. The verdict is that we (in...... the Danish energy sector) are starting to get it right. Lessons for SEA implementation in similar contexts are proposed....

  9. IOMASA SEA ICE DEVELOPMENTS

    DEFF Research Database (Denmark)

    Andersen, Søren; Tonboe, Rasmus; Heygster, Georg

    2005-01-01

    Sensitivity studies show that the radiometer ice concentration estimate can be biased by +10% by anomalous atmospheric emissivity and -20% by anomalous ice surface emissivity. The aim of the sea ice activities in EU 5th FP project IOMASA is to improve sea ice concentration estimates at higher...... spatial resolution. The project is in the process of facilitating an ice concentration observing system through validation and a better understanding of the microwave radiative transfer of the sea ice and overlying snow layers. By use of a novel modelling approach, it is possible to better detect...... and determine the circumstances that may lead to anomalous sea ice concentration retrieval as well as to assess and possibly minimize the sensitivities of the retrieval system. Through an active partnership with the SAF on Ocean and Sea Ice, a prototype system will be implemented as an experimental product...

  10. Indicators and SEA

    DEFF Research Database (Denmark)

    Gao, Jingjing; Kørnøv, Lone; Christensen, Per

    Abstract: Indicators are widely used in SEA to measure, communicate and monitor impacts from a proposed policy, plan or programme, and can improve the effectiveness for the SEA by simplifying the complexity of both assessment and presentation. Indicators can be seen as part of the implementation...... process helping to understand, communicate and, integrate important environmental issues in planning and decision-making. On the other hand, use of indicators can also limit SEA effectiveness, if the ones chosen are biased or limited, if the aggregation gives incorrect interpretation...... and if the information requirement for different target groups is not addressed. Indicators are widely used in SEA to measure, communicate and monitor impacts from a proposed policy, plan or programme, and can improve the effectiveness for the SEA by simplifying the complexity of both assessment and presentation...

  11. IOMASA SEA ICE DEVELOPMENTS

    DEFF Research Database (Denmark)

    Andersen, Søren; Tonboe, Rasmus; Heygster, Georg

    2005-01-01

    Sensitivity studies show that the radiometer ice concentration estimate can be biased by +10% by anomalous atmospheric emissivity and -20% by anomalous ice surface emissivity. The aim of the sea ice activities in EU 5th FP project IOMASA is to improve sea ice concentration estimates at higher...... spatial resolution. The project is in the process of facilitating an ice concentration observing system through validation and a better understanding of the microwave radiative transfer of the sea ice and overlying snow layers. By use of a novel modelling approach, it is possible to better detect...... and determine the circumstances that may lead to anomalous sea ice concentration retrieval as well as to assess and possibly minimize the sensitivities of the retrieval system. Through an active partnership with the SAF on Ocean and Sea Ice, a prototype system will be implemented as an experimental product...

  12. Improved estimates of global sea level change from Ice Sheets, glaciers and land water storage using GRACE

    Science.gov (United States)

    Velicogna, I.; Hsu, C. W.; Ciraci, E.; Sutterley, T. C.

    2015-12-01

    We use observations of time variable gravity from GRACE to estimate mass changes for the Antarctic and Greenland Ice Sheets, the Glaciers and Ice Caps (GIC) and land water storage for the time period 2002-2015 and evaluate their total contribution to sea level. We calculate regional sea level changes from these present day mass fluxes using an improved scaling factor for the GRACE data that accounts for the spatial and temporal variability of the observed signal. We calculate a separate scaling factor for the annual and the long-term components of the GRACE signal. To estimate the contribution of the GIC, we use a least square mascon approach and we re-analyze recent inventories to optimize the distribution of mascons and recover the GRACE signal more accurately. We find that overall, Greenland controls 43% of the global trend in eustatic sea level rise, 16% for Antarctica and 29% for the GIC. The contribution from the GIC is dominated by the mass loss of the Canadian Arctic Archipelago, followed by Alaska, Patagonia and the High Mountains of Asia. We report a marked increase in mass loss for the Canadian Arctic Archipelago. In Greenland, following the 2012 high summer melt, years 2013 and 2014 have slowed down the increase in mass loss, but our results will be updated with summer 2015 observations at the meeting. In Antarctica, the mass loss is still on the rise with increased contributions from the Amundsen Sea sector and surprisingly from the Wilkes Land sector of East Antarctica, including Victoria Land. Conversely, the Queen Maud Land sector experienced a large snowfall in 2009-2013 and has now resumed to a zero mass gain since 2013. We compare sea level changes from these GRACE derived mass fluxes after including the atmospheric and ocean loading signal with sea level change from satellite radar altimetry (AVISO) corrected for steric signal of the ocean using Argo measurements and find an excellent agreement in amplitude, phase and trend in these estimates

  13. Environmental variations in a semi-enclosed embayment (Amvrakikos Gulf, Greece – reconstructions based on benthic foraminifera abundance and lipid biomarker pattern

    Directory of Open Access Journals (Sweden)

    E. Kaberi

    2012-06-01

    Full Text Available The evolution of environmental changes during the last decades and the impact on the living biomass in the western part of Amvrakikos Gulf was investigated using abundances of benthic foraminifera and lipid biomarker concentrations. These proxies indicated that the gulf has dramatically changed due to eutrophication. Eutrophication has led to a higher productivity, a higher bacterial biomass, shifts towards opportunistic and tolerant benthic foraminifera species (e.g. B. elongata, N. turgida, T. agglutinans, A. tepida and a lower benthic species density. Close to the Preveza Straits (connection between the gulf and the Ionian Sea, the benthic assemblages appeared to be less productive and more diversified under more oxygenated conditions. Sea grass meadows largely contributed to the organic matter at this sampling site. Isorenieratane, chlorobactane and lycopane together with oxygen monitoring data indicated that anoxic (and partly euxinic conditions prevailed seasonally throughout the western part of the gulf with more severe hypoxia towards the east. Increased surface water temperatures have led to a higher stratification, which reduced oxygen resupply to bottom waters. These developments are reasons for mass mortality events and ecosystem decline observed in Amvrakikos Gulf.

  14. Near-field sea-level variability in northwest Europe and ice sheet stability during the last interglacial

    Science.gov (United States)

    Long, A. J.; Barlow, N. L. M.; Busschers, F. S.; Cohen, K. M.; Gehrels, W. R.; Wake, L. M.

    2015-10-01

    Global sea level during the Last Interglacial (LIG, Marine Isotope Sub-stage 5e) peaked between c. 5.5 and 9 m above present, implying significant melt from Greenland and Antarctica. Relative sea level (RSL) observations from several far- and intermediate-field sites suggest abrupt fluctuations or jumps in RSL during the LIG highstand that require one or more episodes of ice-sheet collapse and regrowth. Such events should be manifest as unique sea-level fingerprints, recorded in far-, intermediate- and near-field sites depending on the source(s) of ice-mass change involved. To date, though, no coherent evidence of such fluctuations has been reported from near-field RSL studies in northwest Europe. This is an important problem because RSL fluctuations during the LIG are portrayed as warning signs for how polar ice sheets may behave in a future, warmer than present, world. Here we review the evidence for RSL change during the LIG using stratigraphic data from the best resolved highstand records that exist in the near-field of northwest Europe, from a range of settings that include lagoonal, shallow marine, tidal flat, salt marsh and brackish-water fluviatile environments. Consideration of previously published stratigraphic records from two sites in the Eemian coastal-marine embayment that existed in the central Netherlands, yields no clear indications for abrupt RSL change during the attainment of the near-field highstand. Nor do we find any such indications common to other records from countries bordering the North Sea, the Baltic Sea and the White Sea. Two modelling experiments that explore the global signal of hypothetical sea-level oscillations caused by partial collapse and regrowth of either the Greenland or Antarctic LIG ice-sheet, show that the North Sea region is relatively insensitive to mass changes sourced from Greenland but should clearly register events with an Antarctic origin, especially those that occur late in the LIG. The lack of evidence for

  15. Mechanical impact of sea-ice/mélange on marine terminating glaciers

    Science.gov (United States)

    Lindsey, D. S.; Dupont, T. K.

    2011-12-01

    Observations indicate that large portions of ice-sheet margins are currently undergoing rapid dynamic change. The role of the ocean and sea-ice in altering glacier dynamics is currently an active field of research. Sea-ice, along with encased icebergs and marine ice (known as mélange), has been hypothesized to potentially affect glacier calving rates. In winter, sea-ice forms, stiffening the mélange, forming something akin to a thin ice-shelf. In an embayment, the sea-ice/mélange connects embayment walls to the glacial terminus potentially weakening longitudinal strain-rates. As calving rates are strongly dependent on longitudinal strain-rates, a decrease in strain-rate decreases calving. In certain cases decreased calving can lead to a terminus advance resulting in increased lateral drag and decreased glacier velocity. The outlined process is one of several competing theories that help explain the winter terminus advance and associated decrease in velocity at Jakobshavn Isbræ in Greenland. This work assesses the potential mechanical impact sea-ice/mélange (referred hereafter as winter mélange) can have on glacier dynamics. We examine the conditions under which winter mélange can have a significant impact on longitudinal strain-rates. We utilize two calving parameterizations, one depending on ice strain-rate, and the other based on a crevasse depth criterion. Results are presented from a 1-D force balance analysis and 2D plan-view diagnostic model. The 2D model explicitly incorporates the winter mélange as a thin shelf of uniform thickness within the interior of the domain. The model can account for variations in density, thickness, and ice hardness between glacier and winter mélange. Several questions ultimately drive this research. Under what geometric and rheological conditions can winter mélange affect longitudinal strain-rates? How sensitive is the calving rate to a decrease in glacier strain-rate? More specifically, can a small change in

  16. Dead sea water intoxication.

    Science.gov (United States)

    Levy-Khademi, Floris; Brooks, Rebecca; Maayan, Channa; Tenenbaum, Ariel; Wexler, Isaiah D

    2012-08-01

    Near drowning in the Dead Sea is associated with both respiratory manifestations and severe electrolyte abnormalities. It is often difficult to distinguish between the contributions of sea water aspiration or ingestion to clinical manifestations. We present a unique case of accidental ingestion of a large amount of Dead Sea water through a gastrostomy tube in which a patient with familial dysautonomia presented with severe electrolyte disturbances. Forced diuresis with large amounts of intravenous fluids resulted in clinical and biochemical improvement. Full recovery was achieved after 2 days of treatment.

  17. Effects of Large-Scale Releases on the Genetic Structure of Red Sea Bream (Pagrus major, Temminck et Schlegel Populations in Japan.

    Directory of Open Access Journals (Sweden)

    Enrique Blanco Gonzalez

    Full Text Available Large-scale hatchery releases are carried out for many marine fish species worldwide; nevertheless, the long-term effects of this practice on the genetic structure of natural populations remains unclear. The lack of knowledge is especially evident when independent stock enhancement programs are conducted simultaneously on the same species at different geographical locations, as occurs with red sea bream (Pagrus major, Temminck et Schlegel in Japan. In this study, we examined the putative effects of intensive offspring releases on the genetic structure of red sea bream populations along the Japanese archipelago by genotyping 848 fish at fifteen microsatellite loci. Our results suggests weak but consistent patterns of genetic divergence (F(ST = 0.002, p < 0.001. Red sea bream in Japan appeared spatially structured with several patches of distinct allelic composition, which corresponded to areas receiving an important influx of fish of hatchery origin, either released intentionally or from unintentional escapees from aquaculture operations. In addition to impacts upon local populations inhabiting semi-enclosed embayments, large-scale releases (either intentionally or from unintentional escapes appeared also to have perturbed genetic structure in open areas. Hence, results of the present study suggest that independent large-scale marine stock enhancement programs conducted simultaneously on one species at different geographical locations may compromise native genetic structure and lead to patchy patterns in population genetic structure.

  18. The north Sulu Sea productivity

    Science.gov (United States)

    Xiao, Z.

    2009-12-01

    The Sulu Sea is a part of the western North Pacific. It is a closed sea for its deep water and a semi-closed sea for its upper layer. The Sulu Sea exchanges mainly surface waters with the South China Sea and the Celebes Sea. The Sulu Sea is more productive than the adjacent South China Sea (Jones, 2002). On the basis of MERIS satellite observations from 2002 to 2008, we focus on the high-chlorophyll area as an indicator of the abundance of primary productivity in the Sulu Sea. Strong chlorophyll concentration in the north Sulu Sea close to the Mindoro Strait mainly occurs from December to March and low chlorophyll concentration happens in April to November. The adjacent South China Sea on the other side of Mindoro Strait has shown persistent signs of low chlorophyll concentration. Based on 1/8° Global Navy Coastal Ocean Model, the intrusion of the South China Sea waters through the Mindoro Strait to the Sulu Sea from April to November is the main reason for the low chlorophyll concentration observed in the north Sulu Sea. During April to November, the South China Sea waters flow through the Mindoro Strait and stay on the surface of the north Sulu Sea because of their low density. The north Sulu Sea waters mix with fresher waters coming from the South China Sea without new nutrients supply. When the inflow from South China Sea to Sulu Sea ceases in December to March, the upwelling due to the summer monsoon wind becomes an important mechanism supplying deep nutrients to the surface water which lead to high chlorophyll concentration. Jones, I.S.F., 2002. Primary production in the Sulu Sea. Proceedings of the Indian Academy of Sciences-Earth and Planetary Sciences 111, 209-213.

  19. Study of seasonal variation of {sup 222}Rn concentrations to estimate SGD in seawater samples in embayments of Ubatuba, Sao Paulo State, Brazil; Estudo da variacao sazonal das concentracoes de {sup 222}Rn em amostras de agua do mar nas enseadas de Ubatuba, para a estimativa da descarga de aguas subterraneas

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Joselene de; Lopes, Patricia da Costa [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Metrologia das Radiacoes]. E-mail: jolivei@ipen.br; Braga, Elisabete de Santis; Chiozzini, Vitor Gonzalez [Sao Paulo Univ., SP (Brazil). Inst. Oceanografico]. E-mail: edsbraga@usp.br

    2005-07-01

    We describe here an application of excess {sup 222}Rn to estimate SGD in a series of small embayments of Ubatuba, Sao Paulo State, Brazil, covering latitudes between 23 deg 26'S and 23 deg 46'S and longitudes between 45 deg 02'W e 45 deg 11'W. Excess {sup 222}Rn inventories obtained in 11 vertical profiles varied from 3,300 {+-} 1,100 to 18,700 {+-} 4,900 dpm/m2. The estimated total fluxes required to support inventories measured varied from 597 {+-} 199 to 3,385 {+-} 887 dpm/m{sup 2} d. Considering these results, the SGD advective rates necessary to balance the sub-pycnocline fluxes calculated in Ubatuba embayments ranged from 0.6x10{sup -1} to 1.9 cm/d. During the period of this investigation (from March/03 to May/2004), the highest {sup 222}Rn in excess inventories were observed late in the summer season (March). Taking into account all vertical profiles established, the percentual variability was 67%. Although, if we consider only the fluxes determined in both Flamengo and Fortaleza embayments, the percentual variation was 21%.(author)

  20. Seasonal variation of {sup 222}Rn in seawater samples from Ubatuba embayments, SP, Brazil, for the assessment of submarine groundwater discharge; Estudo da variacao sazonal das concentracoes de {sup 222}Rn em amostras de agua do mar nas enseadas de Ubatuba, para a estimativa da descarga de aguas subterraneas

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Patricia da Costa

    2005-07-01

    We describe here an application of excess {sup 222}Rn to estimate SGD in a series of small embayments of Ubatuba, Sao Paulo State, Brazil, covering latitudes between 23 deg 26'S and 23 deg 46'S and longitudes between 45 deg 02'W e 45 deg 11'W. Excess {sup 222}Rn inventories obtained in 24 vertical profiles established from March/03 to July/05 varied from 345 {+-}{+-}24 to 18,700 {+-} 4,900 dpm/m{sup 2}. The highest inventories of excess {sup 222}Rn were observed both in Flamengo and Fortaleza embayments, during summer campaigns (rainy season). The estimated total fluxes required to support inventories measured varied from 62 {+-} 4 to 3,385 +- 880 dpm/m{sup 2} d. Considering these results, the SGD advective rates necessary to balance the fluxes calculated in Ubatuba embayments ranged from 0.1 x 10{sup -1} to 1.9 cm/d. Taking into account all SGD fluxes obtained, the percentual variability was 89% (seasonal variation in 3 years period, n = 24 measurements). Although, if we consider each year of study separately, the respective percentual variabilities estimated are 72% in 2003 (n = 10 measurements), 127% in 2004 (n = 6 measurements) and 97% in 2005 (n = 8 measurements). (author)

  1. Sea Scallop Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Sea Scallop Survey began in 1980 and has covered an area from Cape Hatteras to Georges Bank. The survey aims to determine the distribution and...

  2. Pollution of coastal seas

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    cities. Various types of wastes, if not properly treated, would cause serious pollution of these shallow seas endangering marine life and spoiling recreational facilities. Different polluting agents like sewage, chemicals, industrial coolants etc...

  3. A Sea Floor Penetrometer.

    Science.gov (United States)

    processed through an analog-to-digital (A/D) converter, and stored in the memory of a mini-computer. Computer algorithms are applied to the deceleration data to provide real-time sea floor classification.

  4. Baltic Sea: Radionuclides

    DEFF Research Database (Denmark)

    Nielsen, Sven Poul; Lüning, Maria; Ilus, Erkki

    2011-01-01

    The most significant source of anthropogenic radioactivity in the Baltic Sea is fallout from the accident at the Chernobyl nuclear power plant in 1986. The second most important source is global fallout from atmospheric nuclear weapons tests carried out during the late 1950s and early 1960s....... Radioactivity inputs into the Baltic Sea from nuclear reprocessing plants in Western Europe have become of minor importance due to significant reduction of discharges in recent years. In terms of input of 137Cs into the Baltic Sea, Chernobyl fallout has contributed about 82% and nuclear weapons test fallout...... about 14%. For 90Sr in the Baltic Sea, input from atmospheric fallout from nuclear weapons tests has contributed about 81%, while the contribution from Chernobyl fallout was about 13%. Cesium-137 is the main indicator of Baltic seawater with respect to anthropogenic radioactivity. The highest...

  5. South China Sea.

    Science.gov (United States)

    Morton, B; Blackmore, G

    2001-12-01

    The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km2 and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the

  6. South China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Morton, Brian [Hong Kong Univ., Swire Inst. of Marine Science, Hong Kong (China); Hong Kong Univ., Dept. of Ecology and Biodiversity, Hong Kong (China); Blackmore, Graham [Hong Kong Univ. of Science and Technology, Dept. of Biology, Hong Kong (China)

    2001-07-01

    The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshops and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km{sup 2} and depths range from the shallowest coastal fringe to 5377m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economics on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken

  7. South China Sea

    Science.gov (United States)

    Morton, Brian; Blackmore, Graham

    2001-01-01

    The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km2 and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of the three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the South

  8. Contemporary sea level rise.

    Science.gov (United States)

    Cazenave, Anny; Llovel, William

    2010-01-01

    Measuring sea level change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sea level rise. We first present sea level observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sea level change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sea level rise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sea level trends: The dominant contribution results from nonuniform changes in ocean thermal expansion.

  9. Projecting future sea level

    Science.gov (United States)

    Cayan, Daniel R.; Bromirski, Peter; Hayhoe, Katharine; Tyree, Mary; Dettinger, Mike; Flick, Reinhard

    2006-01-01

    California’s coastal observations and global model projections indicate that California’s open coast and estuaries will experience increasing sea levels over the next century. Sea level rise has affected much of the coast of California, including the Southern California coast, the Central California open coast, and the San Francisco Bay and upper estuary. These trends, quantified from a small set of California tide gages, have ranged from 10–20 centimeters (cm) (3.9–7.9 inches) per century, quite similar to that estimated for global mean sea level. So far, there is little evidence that the rate of rise has accelerated, and the rate of rise at California tide gages has actually flattened since 1980, but projections suggest substantial sea level rise may occur over the next century. Climate change simulations project a substantial rate of global sea level rise over the next century due to thermal expansion as the oceans warm and runoff from melting land-based snow and ice accelerates. Sea level rise projected from the models increases with the amount of warming. Relative to sea levels in 2000, by the 2070–2099 period, sea level rise projections range from 11–54 cm (4.3–21 in) for simulations following the lower (B1) greenhouse gas (GHG) emissions scenario, from 14–61 cm (5.5–24 in) for the middle-upper (A2) emission scenario, and from 17–72 cm (6.7–28 in) for the highest (A1fi) scenario. In addition to relatively steady secular trends, sea levels along the California coast undergo shorter period variability above or below predicted tide levels and changes associated with long-term trends. These variations are caused by weather events and by seasonal to decadal climate fluctuations over the Pacific Ocean that in turn affect the Pacific coast. Highest coastal sea levels have occurred when winter storms and Pacific climate disturbances, such as El Niño, have coincided with high astronomical tides. This study considers a range of projected future

  10. New model for Jurassic microcontinent movement and Gondwana breakup in the Weddell Sea region

    Science.gov (United States)

    Jordan, Tom; Ferraccioli, Fausto; Leat, Philip

    2017-04-01

    The breakup of the Gondwana supercontinent changed the face of our planet. Precursors of supercontinental breakup are widely recognised in the Weddell Sea region in the Jurassic. These include the Karoo/Ferrar Large Igneous Province that extends from South Africa to East Antarctica and significant continental rifting and associated translation of microcontinental blocks in the Weddell Sea Embayment region. However, significant controversy surrounds the pre-breakup position, extent, timing and driving mechanism of inferred microcontinental movement. In particular geological and paleomagnetic data suggest >1000 km of translation and 90 degree rotation of the Haag-Ellsworth Whitmore block (HEW) away from East Antarctica. In contrast, some geophysical interpretations suggest little or no Jurassic or subsequent HEW block movement. Here we present a simpler tectonic model for the Weddell Sea Rift System and HEW movement, derived from our new compilation of airborne geophysical data, satellite magnetic data and potential field modelling (Jordan et al., 2016- Gondwana Res.). Based on the amount of inferred Jurassic crustal extension and pattern of magnetic anomalies we propose that the HEW was translated 500 km towards the Paleo-Pacific margin of Gondwana, possibly in response to a process of slab roll-back that led to distributed back-arc extension in the Weddell Sea Rift System. Widespread magmatism in the region was likely influenced by the presence of one or more mantle plumes impinging beneath the stretching lithosphere. A second phase of continental extension is inferred to have occurred between 180 and 165 Ma (prior to seafloor spreading) and is more closely associated with Gondwana breakup. This second phase over-printed the northern part of the older back arc system. We find no geophysical evidence indicating more than 30 degrees of syn-extensional HEW rotation during Jurassic rifting in the southern Weddell Sea Rift System. Instead, we propose the majority ( 60

  11. The Dead Sea

    Science.gov (United States)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining

  12. The Dead Sea

    Science.gov (United States)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining

  13. Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis

    Directory of Open Access Journals (Sweden)

    I. Tolosa

    2013-03-01

    Full Text Available Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids and compound-specific isotope analysis of suspended particulate organic matter (SPM and surface sediments of the Mackenzie Shelf and slope (southeast Beaufort Sea, Arctic Ocean were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the organic matter (OM of this area. Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and 80%, with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60–75%, whereas those from the slope contained the highest proportion of fossil (40% and C3 terrestrial plant material (10%. Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the sediments accounted for 30–40% of the total carbon in the inner shelf sediments, 17% in the outer shelf and Amundsen Gulf and up to 25% in the slope sediments. These estimates are low

  14. Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis

    Science.gov (United States)

    Tolosa, I.; Fiorini, S.; Gasser, B.; Martín, J.; Miquel, J. C.

    2013-03-01

    Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids) and compound-specific isotope analysis of suspended particulate organic matter (SPM) and surface sediments of the Mackenzie Shelf and slope (southeast Beaufort Sea, Arctic Ocean) were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the organic matter (OM) of this area. Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and 80%), with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60-75%), whereas those from the slope contained the highest proportion of fossil (40%) and C3 terrestrial plant material (10%). Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC) found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the sediments accounted for 30-40% of the total carbon in the inner shelf sediments, 17% in the outer shelf and Amundsen Gulf and up to 25% in the slope sediments. These estimates are low compared to other

  15. Kara Sea radioactivity assessment

    Energy Technology Data Exchange (ETDEWEB)

    Osvath, I.; Povinec, P.P.; Baxter, M.S. [Marine Environment Laboratory, International Atomic Energy Agency, B.P. 800 MC (Monaco)

    1999-09-30

    Investigations following five international expeditions to the Kara Sea have shown that no radiologically significant contamination has occurred outside of the dumping sites in Novaya Zemlya bays. Increased levels of radionuclides in sediment have only been observed in Abrosimov and Stepovoy Bays very close to dumped containers. Evaluations of radionuclide inventories in water and sediment of the open Kara Sea and Novaya Zemlya bays as well as soil from the shore of Abrosimov bay have shown that radionuclide contamination of the open Kara Sea is mainly due to global fallout, with smaller contributions from the Sellafield reprocessing plant, the Chernobyl accident run-off from the Ob and Yenisey rivers and local fallout. Computer modelling results have shown that maximum annual doses of approximately 1 mSv are expected for a hypothetical critical group subsisting on fish caught in the Novaya Zemlya bays whereas populations living on the mainland can be expected to receive doses at least three orders of magnitude lower.

  16. Sea Spray Aerosols

    DEFF Research Database (Denmark)

    Butcher, Andrew Charles

    emissions produced directly from bubble bursting as the result of air entrainment from breaking waves and particles generated from secondary emissions of volatile organic compounds. In the first paper, we study the chemical properties of particles produced from several sea water proxies with the use...... of a cloud condensation nuclei ounter. Proxy solutions with high inorganic salt concentrations and some organics produce sea spray aerosol particles with little change in cloud condensation activity relative to pure salts. Comparison is made between a frit based method for bubble production and a plunging...... a relationship between plunging jet particle ux, oceanic particle ux, and energy dissipation rate in both systems. Previous sea spray aerosol studies dissipate an order of magnitude more energy for the same particle ux production as the open ocean. A scaling factor related to the energy expended in air...

  17. Sea Spray Aerosols

    DEFF Research Database (Denmark)

    Butcher, Andrew Charles

    emissions produced directly from bubble bursting as the result of air entrainment from breaking waves and particles generated from secondary emissions of volatile organic compounds. In the first paper, we study the chemical properties of particles produced from several sea water proxies with the use...... of a cloud condensation nuclei ounter. Proxy solutions with high inorganic salt concentrations and some organics produce sea spray aerosol particles with little change in cloud condensation activity relative to pure salts. Comparison is made between a frit based method for bubble production and a plunging...... a relationship between plunging jet particle ux, oceanic particle ux, and energy dissipation rate in both systems. Previous sea spray aerosol studies dissipate an order of magnitude more energy for the same particle ux production as the open ocean. A scaling factor related to the energy expended in air...

  18. Dynamics of sea level variations in the coastal Red Sea

    Science.gov (United States)

    Churchill, James; Abulnaja, Yasser; Nellayaputhenpeedika, Mohammedali; Limeburner, Richard; Lentz, Steven

    2016-04-01

    Sea level variations in the central Red Sea coastal zone span a range of roughly 1.2 m. Though relatively small, these water level changes can significantly impact the environment over the shallow reef tops prevalent in the central Red Sea, altering the water depth by a factor or two or more. While considerable scientific work has been directed at tidal and seasonal variations of Red Sea water level, very little attention has been given to elevation changes in an 'intermediate' frequency band, with periods of 2-30 d, even though motions in this band account for roughly half of the sea level variance in central Red Sea. We examined the sea level signal in this band using AVISO sea level anomaly (SLA) data, COARDAS wind data and measurements from pressure sensors maintained for more than five years at a number of locations in Saudi Arabian coastal waters. Empirical orthogonal function analysis of the SLA data indicates that longer-period (10-30 d) sea level variations in the intermediate band are dominated by coherent motions in a single mode that extends over most of the Red Sea axis. Idealized model results indicate that this large-scale mode of sea level motion is principally due to variations in the large-scale gradient of the along-axis wind. Our analysis indicates that coastal sea level motions at shorter periods (2-10 d) are principally generated by a combination of direct forcing by the local wind stress and forcing associated with large-scale wind stress gradients. However, also contributing to coastal sea level variations in the intermediate frequency band are mesoscale eddies, which are prevalent throughout the Red Sea basin, have a sea level signal of 10's of cm and produce relatively small-scale (order 50 km) changes in coastal sea level.

  19. Mediterranean, our sea

    Science.gov (United States)

    Markaki, Foteini

    2017-04-01

    My school (1o EPAL Ymittos -Athens, Greece) is a technical school of secondary education and throughout this school year being drafted a program of environmental education. The main theme is the Mediterranean Sea, the biggest closed sea extending between three continents. Topics studied: 1. Biodiversity and the risks threat. 2. The geophysics that characterize (earthquakes, volcanoes explosions, etc). 3. The Mediterranean Sea as environment anthropogenesis, a mosaic of other cultures and even place current notions of social phenomena (refugees). Pedagogical Objectives: Cognitive/Enviromental: 1. To investigate and understand the biodiversity of the Mediterranean Sea and the risks to threaten and phenomena that characterize. 2. To understand the position of the Mediterranean Sea in the land and the role of the historical, cultural and social human environment. 3. To come in contact with texts literary, social, articles on the Mediterranean. Psychomotor: 1. To work together and collect information for the Mediterranean Sea. 2. Experiential approach to the natural environment. 3. Develop critical thinking. 4. Undertake responsibilities for the presentation of the program. Emotional: 1. To feel joy from participation in the program. 2. Being sensitized and configure attitudes and actions of respect towards the environment. Methodology implementation: Teamwork. Interdisciplinary - holistic to dissemination of program recordings to courses curriculum. Study in the field. Gathering information from newspapers, magazines, internet, maps, and photographs. Experiential method- Project. Assessment methods and self-assessment. Fields of courses: Greek language- History- Biology- Chemistry- Technology Dissemination of results: Make a page of social media (facebook), a blog, enhancing environmental awareness via video, make an electronic poster.

  20. Dinoflagellate cyst production in Hudson Bay, the world's largest inland sea, based on monthly sediment trap data

    Science.gov (United States)

    Heikkilä, Maija; Pospelova, Vera; Forest, Alexandre; Stern, Gary

    2014-05-01

    Phytoplankters, microscopic primary producers of oceans are capable of responding rapidly to environmental fluctuations due to their high cell replication rates. Fast phytoplankton growth maybe balanced out by equally fast consumption by herbivorous grazers. In high-latitude marine systems, seasonal fluctuations in plankton biomass are essentially linked to light regime controlled by the waxing and waning sea-ice cover. In addition, nutrient limitation in surface waters, seasonal temperature fluctuations and changes in freshwater inputs may play important roles. In cold-water seas, many planktonic organisms cope with seasonal harshness by the production of benthic dormant stages. Dinoflagellates are a diverse group of single-celled plankton, constituting major marine primary producers, as well as herbivorous grazers of the microbial loop. Many dinoflagellate species produce highly resistant, organic-walled resting cysts that are archived in sediments and have been increasingly used to reconstruct past environmental conditions, e.g., sea-surface temperature and salinity, productivity, sea-ice cover and eutrophication. Marine sediment core sequences are characterized by slow accumulation rates and high mixing rates: the top centimeter of surface sediment from an arctic shelf may correspond to several years or decades of deposition. Consequently, sedimentary archives do not give direct information on long-term changes in seasonal bloom patterns or cues of annually recurring life-cycle events. We used two particle-intercepting sediment traps moored in eastern and western Hudson Bay, respectively, to study monthly fluctuations in dinoflagellate cyst production from October 2005 to September 2006. The traps were deployed close to the seafloor and recovered during the ArcticNet annual expeditions onboard the CCGS Amundsen in 2005 and the CCGS Pierre Radisson in 2006. We document the seasonal succession of dinoflagellate cyst taxa, together with cyst species composition

  1. Seasonal Change of Steric Sea Level in the GIN Seas

    Institute of Scientific and Technical Information of China (English)

    LI Lei; WANG Huijuan; SUN Ruili

    2011-01-01

    The Greenland Sea, Iceland Sea, and Norwegian Sea (GIN seas) form the main channel connecting the Arctic Ocean with other Oceans, where significant water and energy exchange take place, and play an important role in global climate change. In this study steric sea level, associated with temperature and salinity, in the GIN seas is examined based on analysis of the monthly temperature and salinity fields from Polar science center Hydrographic Climatology (PHC3.0). A method proposed by Tabata et al. is used to calculate steric sea level, in which, steric sea level change due to thermal expansion and haline contraction is termed as the thermosteric component (TC) and the halosteric component (SC), recpectively. Total steric sea level (TSSL) change is the sum of TC and SC. The study shows that SC is making more contributions than TC to the seasonal change of TSSL in the Greenland Sea, whereas TC contributes more in the Norwegian and the Iceland Seas. Annual variation of TSSL is larger than 50ram over most regions of the GIN Seas, and can be larger than 200mm at some locations such as 308mm at 76.5°N, 12.5°E and 246mm at 77.50N, 17.5°W.

  2. Analysis of Sea Spikes in Radar Sea Clutter Data

    NARCIS (Netherlands)

    Melief, H.W.; Greidanus, H.; Genderen, P. van; Hoogeboom, P.

    2006-01-01

    Abstract—In this paper three sets of high-resolution, coherent, and polarimetric radar sea clutter data are analyzed and compared with radar sea clutter models. The nature of the data allows a thorough analysis of the power, polarization and velocity of the sea clutter. It is shown that these

  3. Analysis of Sea Spikes in Radar Sea Clutter Data

    NARCIS (Netherlands)

    Melief, H.W.; Greidanus, H.; Genderen, P. van; Hoogeboom, P.

    2006-01-01

    Abstract—In this paper three sets of high-resolution, coherent, and polarimetric radar sea clutter data are analyzed and compared with radar sea clutter models. The nature of the data allows a thorough analysis of the power, polarization and velocity of the sea clutter. It is shown that these quanti

  4. Air-sea exchange studies at the North Sea

    NARCIS (Netherlands)

    Leeuw, G. de; Eijk, A.M.J. van; Kunz, G.J.; Veefkind, P.J.

    1996-01-01

    The North Sea can be considered as a local 'inner' sea in which many processes are quite different from these over the open ocean. The surrounding land has a major influence, being the source for man-made aerosols and gases, whereas the North Sea acts as a sink for these. At the same time the North

  5. Storm-Based Fluvial Inputs: Nutrient, Phytoplankton, and Carbon Dioxide Responses in a Tropical Embayment, Kane'ohe Bay, Hawai'i

    Science.gov (United States)

    Drupp, P. S.; de Carlo, E. H.; MacKenzie, F. T.; Bienfang, P.

    2010-12-01

    This work describes use of a buoy system to monitor, autonomously, pCO2 and water quality responses to land-derived nutrient inputs and the physical forcings associated with local storm events. These data represent 2.5 years of near-real time observations at a fixed station, collected concurrently with spatially distributed synoptic sampling over larger sections of Kaneohe Bay, Oahu, Hawaii. Nutrient loadings from direct rainfall and/or terrestrial runoff produce an immediate increase in the N:P ratio of bay waters up to 48, and drive phytoplankton biomass growth. Rapid uptake of nutrient input subsidies by phytoplankton causes a rapid decline of pCO2 and nitrogen, before a return to baseline levels with the subsequent decline of phytoplankton biomass over time scales ranging from a few days to several weeks, depending on the conditions and proximity to the sources of runoff. This work exemplifies the utility of combining synoptic sampling and real-time autonomous observations to elucidate the responses of coastal tropical coral reef systems to climatic perturbations over the array of time scales (hours to annual) on which they occur. Many subtropical and tropical systems throughout the Pacific Ocean are similar to Kaneohe Bay and our studies of how coral reef ecosystems respond under conditions of increased ocean acidification provides an important indication of the variability and range of CO2 dynamics that are likely to exist elsewhere. Such variability must be taken into account in any analysis of the direction and magnitude of the air-sea CO2 exchange for the integrated coastal ocean, both proximal and distal. Finally, it cannot be overemphasized that our work illustrates several examples of how high frequency sampling provided by a moored autonomous system can provide details about ecosystem responses to stochastic atmospheric forcing, which are commonly missed by traditional synoptic observational approaches. Figure 1: pCO2 levels and nitrate concentrations

  6. SEA LEVEL (TOPEX/POSEIDON)

    Data.gov (United States)

    National Aeronautics and Space Administration — Sea level rise is caused by the thermal expansion of sea water due to climate warming and widespread melting of land ice. The TOPEX/POSEIDON mission a joint...

  7. Atlantic Flyway Sea Duck Survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Atlantic Flyway Sea Duck Survey, conducted from 1991 to 2002 by the U.S. Fish and Wildlife Service, was established to record sea duck numbers using near shore...

  8. Seafloor Control on Sea Ice

    Science.gov (United States)

    Nghiem, S. V.; Clemente-Colon, P.; Rigor, I. G.; Hall, D. K.; Neumann, G.

    2011-01-01

    The seafloor has a profound role in Arctic sea ice formation and seasonal evolution. Ocean bathymetry controls the distribution and mixing of warm and cold waters, which may originate from different sources, thereby dictating the pattern of sea ice on the ocean surface. Sea ice dynamics, forced by surface winds, are also guided by seafloor features in preferential directions. Here, satellite mapping of sea ice together with buoy measurements are used to reveal the bathymetric control on sea ice growth and dynamics. Bathymetric effects on sea ice formation are clearly observed in the conformation between sea ice patterns and bathymetric characteristics in the peripheral seas. Beyond local features, bathymetric control appears over extensive ice-prone regions across the Arctic Ocean. The large-scale conformation between bathymetry and patterns of different synoptic sea ice classes, including seasonal and perennial sea ice, is identified. An implication of the bathymetric influence is that the maximum extent of the total sea ice cover is relatively stable, as observed by scatterometer data in the decade of the 2000s, while the minimum ice extent has decreased drastically. Because of the geologic control, the sea ice cover can expand only as far as it reaches the seashore, the continental shelf break, or other pronounced bathymetric features in the peripheral seas. Since the seafloor does not change significantly for decades or centuries, sea ice patterns can be recurrent around certain bathymetric features, which, once identified, may help improve short-term forecast and seasonal outlook of the sea ice cover. Moreover, the seafloor can indirectly influence cloud cover by its control on sea ice distribution, which differentially modulates the latent heat flux through ice covered and open water areas.

  9. Pollution around Malta's sea

    OpenAIRE

    Formosa, Nicolette; Duca, Edward

    2014-01-01

    Marine littering is a global concern and every single year tons of litter end up in the ocean all around the globe. It has become such a problem that the waste has amalgamated into huge ‘islands’ floating in the world’s oceans. http://www.um.edu.mt/think/pollution-around-maltas-sea/

  10. Wadden Sea Mud

    DEFF Research Database (Denmark)

    Møller-Jensen, P.

    The present thesis deals with the transport phenomena of estuarine cohesive sediment from a laboratory and a numerical point of view. The cohesive sediment used throughout the whole process was natural mud from the Danish part of the Wadden sea, Ho Bay. In the laboratory, the work was concentrated...

  11. Sailing the Cyber Sea

    Science.gov (United States)

    2012-04-01

    years, the Internet 4 years, and the iPod 3 years, while Facebook added 200 million users in less than 1 year. And finally, if Facebook were a... Apple ] gets an iPhone. It’s not an acceptable trade.” New Thinking In the context of security, unleashing the power of the Cyber Sea has changed

  12. Wadden Sea Mud

    DEFF Research Database (Denmark)

    Møller-Jensen, P.

    The present thesis deals with the transport phenomena of estuarine cohesive sediment from a laboratory and a numerical point of view. The cohesive sediment used throughout the whole process was natural mud from the Danish part of the Wadden sea, Ho Bay. In the laboratory, the work was concentrated...

  13. Pollution around Malta's sea

    OpenAIRE

    Formosa, Nicolette

    2014-01-01

    Marine littering is a global concern and every single year tons of litter end up in the ocean all around the globe. It has become such a problem that the waste has amalgamated into huge ‘islands’ floating in the world’s oceans. http://www.um.edu.mt/think/pollution-around-maltas-sea/

  14. Solar Sea Power

    Science.gov (United States)

    Zener, Clarence

    1976-01-01

    In their preoccupation with highly complex new energy systems, scientists and statesmen may be overlooking the possibilities of Ocean Thermal Energy Conversion (OTEC). That is the view of a Carnegie-Mellon University physicist who is in the forefront of solar sea power investigation. (Author/BT)

  15. Baltic Sea: Radionuclides

    DEFF Research Database (Denmark)

    Nielsen, Sven Poul; Lüning, Maria; Ilus, Erkki

    2010-01-01

    The most significant source of anthropogenic radioactivity in the Baltic Sea is fallout from the accident at the Chernobyl nuclear power plant in 1986. The second most important source is global fallout from atmospheric nuclear weapons tests carried out during the late 1950s and early 1960s. Radi...

  16. Solomon's Sea and [Pi

    Science.gov (United States)

    Simoson, Andrew J.

    2009-01-01

    This paper is a whimsical survey of the various explanations which might account for the biblical passage in I Kings 7:23 that describes a round object--a bronze basin called Solomon's Sea--as having diameter ten cubits and circumference thirty cubits. Can the biblical pi be any number other than 3? We offer seven different perspectives on this…

  17. Deep-sea fungi

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Damare, S.

    The deep-sea environment, despite being rich in mineral nutrients and near-saturation levels of oxygen, because of its darkness is not conducive to photosynthesis, the process that sustains life on earth. If a liigh abundance and diversity of life...

  18. Effect of temperature on two reef-building corals Pocillopora damicornis and P. verrucosa in the Red Sea

    Directory of Open Access Journals (Sweden)

    Abdulmohsin A. Al-Sofyani

    2013-11-01

    Full Text Available The effects of temperature on two reef building corals Pocilloporadamicornis and P. verrucosa inhabiting the Obhur Creek, a small embayment on thewestern, Red Sea coast of Saudi Arabia, was studied from December 2009 toNovember 2010. The overall annual range of seawater temperature in Obhur Creekwas between 24.5°C and 33°C. Zooxanthellae abundance anddiversity showed seasonal variations: the number of zooxanthellae in P. damicornis was slightly higher than in P. verrucosa, and theabundance of zooxanthellae of both species was low in summer and high duringwinter. The respiration rate of P. verrucosa did not vary between summerand winter, suggesting compensatory acclimation. In contrast, the respiratoryrate in P. damicornis was lower in winter than in summer. During thewinter season the metabolic rate was higher in both species owing to theoptimum seawater temperature (30°C. As a result of the abundance ofzooxanthellae and the optimum seawater temperature, the growth rates of theskeletons of the two coral species were higher in winter and lower in summer.In general, the results showed that P. damicornis is more flexible withrespect to temperature than P. damicornis. The difference inzooxanthellae thermal tolerances at 35°C may be due to the algalgenotypes between the two species, resulting in P. damicornis becomingbleached as the rate of metabolism exceeds the rate of photosynthesis withincreasing temperature.

  19. Biogeography and Photosynthetic Biomass of Arctic Marine Pico-Eukaroytes during Summer of the Record Sea Ice Minimum 2012.

    Science.gov (United States)

    Metfies, Katja; von Appen, Wilken-Jon; Kilias, Estelle; Nicolaus, Anja; Nöthig, Eva-Maria

    2016-01-01

    Information on recent photosynthetic biomass distribution and biogeography of Arctic marine pico-eukaryotes (0.2-3 μm) is needed to better understand consequences of environmental change for Arctic marine ecosystems. We analysed pico-eukaryote biomass and community composition in Fram Strait and large parts of the Central Arctic Ocean (Nansen Basin, Amundsen Basin) using chlorophyll a (Chl a) measurements, automated ribosomal intergenic spacer analysis (ARISA) and 454-pyrosequencing. Samples were collected during summer 2012, the year with the most recent record sea ice minimum. Chl a concentrations were highest in eastern Fram Strait and pico-plankton accounted for 60-90% of Chl a biomass during the observation period. ARISA-patterns and 454-pyrosequencing revealed that pico-eukaryote distribution is closely related to water mass distribution in the euphotic zone of the Arctic Ocean. Phaeocystaceae, Micromonas sp., Dinophyceae and Syndiniales constitute a high proportion of sequence reads, while sequence abundance of autotrophic Phaeocystaceae and mixotrophic Micromonas sp. was inversely correlated. Highest sequence abundances of Phaeocystaceae were observed in the warm Atlantic Waters in Fram Strait, while Micromonas sp. dominated the abundant biosphere in the arctic halocline. Our results are of particular interest considering existing hypotheses that environmental conditions in Nansen Basin might become more similar to the current conditions in Fram Strait. We propose that in response, biodiversity and biomass of pico-eukaryotes in Nansen Basin could resemble those currently observed in Fram Strait in the future. This would significantly alter biogeochemical cycles in a large part of the Central Arctic Ocean.

  20. Biogeography and Photosynthetic Biomass of Arctic Marine Pico-Eukaroytes during Summer of the Record Sea Ice Minimum 2012.

    Directory of Open Access Journals (Sweden)

    Katja Metfies

    Full Text Available Information on recent photosynthetic biomass distribution and biogeography of Arctic marine pico-eukaryotes (0.2-3 μm is needed to better understand consequences of environmental change for Arctic marine ecosystems. We analysed pico-eukaryote biomass and community composition in Fram Strait and large parts of the Central Arctic Ocean (Nansen Basin, Amundsen Basin using chlorophyll a (Chl a measurements, automated ribosomal intergenic spacer analysis (ARISA and 454-pyrosequencing. Samples were collected during summer 2012, the year with the most recent record sea ice minimum. Chl a concentrations were highest in eastern Fram Strait and pico-plankton accounted for 60-90% of Chl a biomass during the observation period. ARISA-patterns and 454-pyrosequencing revealed that pico-eukaryote distribution is closely related to water mass distribution in the euphotic zone of the Arctic Ocean. Phaeocystaceae, Micromonas sp., Dinophyceae and Syndiniales constitute a high proportion of sequence reads, while sequence abundance of autotrophic Phaeocystaceae and mixotrophic Micromonas sp. was inversely correlated. Highest sequence abundances of Phaeocystaceae were observed in the warm Atlantic Waters in Fram Strait, while Micromonas sp. dominated the abundant biosphere in the arctic halocline. Our results are of particular interest considering existing hypotheses that environmental conditions in Nansen Basin might become more similar to the current conditions in Fram Strait. We propose that in response, biodiversity and biomass of pico-eukaryotes in Nansen Basin could resemble those currently observed in Fram Strait in the future. This would significantly alter biogeochemical cycles in a large part of the Central Arctic Ocean.

  1. The North Sea - A shelf sea in the Anthropocene

    Science.gov (United States)

    Emeis, Kay-Christian; van Beusekom, Justus; Callies, Ulrich; Ebinghaus, Ralf; Kannen, Andreas; Kraus, Gerd; Kröncke, Ingrid; Lenhart, Hermann; Lorkowski, Ina; Matthias, Volker; Möllmann, Christian; Pätsch, Johannes; Scharfe, Mirco; Thomas, Helmuth; Weisse, Ralf; Zorita, Eduardo

    2015-01-01

    Global and regional change clearly affects the structure and functioning of ecosystems in shelf seas. However, complex interactions within the shelf seas hinder the identification and unambiguous attribution of observed changes to drivers. These include variability in the climate system, in ocean dynamics, in biogeochemistry, and in shelf sea resource exploitation in the widest sense by societies. Observational time series are commonly too short, and resolution, integration time, and complexity of models are often insufficient to unravel natural variability from anthropogenic perturbation. The North Sea is a shelf sea of the North Atlantic and is impacted by virtually all global and regional developments. Natural variability (from interannual to multidecadal time scales) as response to forcing in the North Atlantic is overlain by global trends (sea level, temperature, acidification) and alternating phases of direct human impacts and attempts to remedy those. Human intervention started some 1000 years ago (diking and associated loss of wetlands), expanded to near-coastal parts in the industrial revolution of the mid-19th century (river management, waste disposal in rivers), and greatly accelerated in the mid-1950s (eutrophication, pollution, fisheries). The North Sea is now a heavily regulated shelf sea, yet societal goals (good environmental status versus increased uses), demands for benefits and policies diverge increasingly. Likely, the southern North Sea will be re-zoned as riparian countries dedicate increasing sea space for offshore wind energy generation - with uncertain consequences for the system's environmental status. We review available observational and model data (predominantly from the southeastern North Sea region) to identify and describe effects of natural variability, of secular changes, and of human impacts on the North Sea ecosystem, and outline developments in the next decades in response to environmental legislation, and in response to

  2. SEA/WOMAN

    OpenAIRE

    Furse, Anna F. D.

    2011-01-01

    A new laboratory research performance by Anna Furse, Athletes of the Heart, UK) in collaboration with Maja Mitic (DAH Teatar, Serbia) and Antonella Diana (Teatret OM, Denmark) based on Henrik Ibsen's 'The lady from the sea' (1888). The project is an AHRC/ACE funded project as part of the Pinter Centre for Performance and Creative Writing's Fractured Narratives project. It has been touring in the UK and to Beirut, Lebanon.

  3. SEA/WOMAN

    OpenAIRE

    Furse, Anna F. D.

    2011-01-01

    A new laboratory research performance by Anna Furse, Athletes of the Heart, UK) in collaboration with Maja Mitic (DAH Teatar, Serbia) and Antonella Diana (Teatret OM, Denmark) based on Henrik Ibsen's 'The lady from the sea' (1888).\\ud \\ud The project is an AHRC/ACE funded project as part of the Pinter Centre for Performance and Creative Writing's Fractured Narratives project. It has been touring in the UK and to Beirut, Lebanon.

  4. Sea Basing Logistiek

    Science.gov (United States)

    2007-11-01

    iets wat nu voor zware goederen niet mogeljk is met de middelen binnen de Nederlandse krijgsmachit. Nederland heeft bijvoorbeeld (nog) geen specifieke...weer gevechtsklaar zijn. Nederlandse troepen voeren de reconstitute fase in het algemeen uit in Nederland . [Kang&Gue] A special concern in sea based...besluit Nederland zelf in te grijpen. De Nederlandse vredesmissie bevindt zich nabij de kust. maar ver van de grens met buurlanden. De operatie kan niet

  5. Armada puts to sea

    Energy Technology Data Exchange (ETDEWEB)

    Esau, I.

    1995-04-01

    This article describes the operational success of British Gas in exploiting the Armada gas field. Armada consists of three separate reservoirs (Fleming, Drake and Hawkins) and lies in the central North Sea. British Gas has successfully exploited this field on behalf of a group of co-venturers. This article describes the economic, technical and political difficulties faced by the company in operating this innovative method of management. (UK)

  6. Dead Sea rhodopsins revisited.

    Science.gov (United States)

    Bodaker, Idan; Suzuki, Marcelino T; Oren, Aharon; Béjà, Oded

    2012-12-01

    The Dead Sea is a unique hypersaline ecosystem with near toxic magnesium levels (∼2 M), dominance of divalent cations and a slightly acidic pH. Previously, we reported a haloarchaeon related to Halobacterium salinarum to dominate in a microbial bloom that developed in 1992 in the upper water layers of the lake following massive freshwater runoff. Whether this clade also dominated an earlier bloom in 1980-1982 cannot be ascertained as no samples for cultivation-independent analysis were preserved. The presence of the light-driven proton pump bacteriorhodopsin was reported in the 1980-1982 bloom of prokaryotes that had developed in the Dead Sea. To test the hypothesis that bacteriorhodopsin proton pumping may play a major role in determining what type of haloarchaea may dominate in specific bloom conditions, we compared rhodopsin genes recovered from Dead Sea biomass collected in different periods with genes coding for retinal proteins in isolated haloarchaea. Novel bacteriorhodopsin and sensory rhodopsin genes were found in samples collected in 2007 and 2010. The fact that no rhodopsin genes were recovered from samples collected during the 1992 bloom, which was dominated by a single species, suggests that different clades were present in the 1980-1982 and 1992 blooms, and that bacteriorhodopsin proton pumping did not necessarily play a determinative role in the dominance of specific halophiles in the blooms.

  7. Arctic Sea Ice

    Science.gov (United States)

    Stroeve, J. C.; Fetterer, F.; Knowles, K.; Meier, W.; Serreze, M.; Arbetter, T.

    2004-12-01

    Of all the recent observed changes in the Arctic environment, the reduction of sea ice cover stands out most prominantly. Several independent analysis have established a trend in Arctic ice extent of -3% per decade from the late 1970s to the late 1990s, with a more pronounced trend in summer. The overall downward trend in ice cover is characterized by strong interannual variability, with a low September ice extent in one year typically followed by recovery the next September. Having two extreme minimum years, such as what was observed in 2002 and 2003 is unusual. 2004 marks the third year in a row of substantially below normal sea ice cover in the Arctic. Early summer 2004 appeared unusual in terms of ice extent, with May a record low for the satellite period (1979-present) and June also exhibiting below normal ice extent. August 2004 extent is below that of 2003 and large reductions in ice cover are observed once again off the coasts of Siberia and Alaska and the Greenland Sea. Neither the 2002 or 2003 anomaly appeared to be strongly linked to the positive phase of the Arctic Oscillation (AO) during the preceding winter. Similarly, the AO was negative during winter 2003/2004. In the previous AO framework of Rigor et al (2002), a positive winter AO implied preconditioning of the ice cover to extensive summer decay. In this hypothesis, the AO does not explain all aspects of the recent decline in Arctic ice cover, such as the extreme minima of 2002, 2003 and 2004. New analysis by Rigor and Wallace (2004) suggest that the very positive AO state from 1989-1995 can explain the recent sea ice minima in terms of changes in the Arctic surface wind field associated with the previous high AO state. However, it is also reasonable to expect that a general decrease in ice thickness accompanying warming would manifest itself as greater sensitivity of the ice pack to wind forcings and albedo feedbacks. The decrease in multiyear ice and attendant changes in ice thickness

  8. Highly variable Pliocene sea surface conditions in the Norwegian Sea

    Science.gov (United States)

    Bachem, Paul E.; Risebrobakken, Bjørg; De Schepper, Stijn; McClymont, Erin L.

    2017-09-01

    The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial-interglacial variability. Here, we present high-resolution records of sea surface temperature (SST) and ice-rafted debris (IRD) in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 °C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere glaciation. Cooling from 4.5 to 4.3 Ma may be linked to the onset of poleward flow through the Bering Strait. This cooling was further intensified by a period of cool summers due to weak obliquity forcing. A 7 °C warming of the Norwegian Sea at 4.0 Ma suggests a major increase in northward heat transport from the North Atlantic, leading to an enhanced zonal SST gradient in the Nordic Seas, which may be linked to the expansion of sea ice in the Arctic and Nordic Seas. A warm Norwegian Sea and enhanced zonal temperature gradient between 4.0 and 3.6 Ma may have been a priming factor for increased glaciation around the Nordic Seas due to enhanced evaporation and precipitation at high northern latitudes.

  9. Bindin from a sea star

    OpenAIRE

    Patiño, Susana; Jan E. Aagaard; MacCoss, Michael J.; Swanson, Willie J.; Hart, Michael W

    2009-01-01

    The genetic basis for the evolution of development includes genes that encode proteins expressed on the surfaces of sperm and eggs. Previous studies of the sperm acrosomal protein bindin have helped to characterize the adaptive evolution of gamete compatibility and speciation in sea urchins. The absence of evidence for bindin expression in taxa other than the Echinoidea has limited such studies to sea urchins, and led to the suggestion that bindin might be a sea urchin-specific molecule. Here...

  10. Sea Salt Source Function over the Baltic Sea

    Science.gov (United States)

    Petelski, Tomasz; Makuch, Przemyslaw; Markuszewski, Piotr; Jankowski, Andrzej; Zieliński, Tymon

    2013-04-01

    Studies of production and transport of aerosol over the sea are very important for many areas of knowledge. Marine aerosol emitted from the sea surface helps to clean the boundary layer from other aerosol particles. The emitted droplets do not dry out in the highly humid surface layer air and because of their sizes most of them are deposited quickly at the sea surface. Therefore, marine aerosol has many features of rain i.e. the deposition in the marine boundary layer in high wind events is controlled not only by the "dry" processes but also by the "wet" scavenging. While many cruises conducted on board S/Y Oceania, we collected many data which were used to calculate sea salt source function over the Baltic Sea. Our cruises held between 2009 and 2012. Measurements were carried out using gradient method. For this method we used Laser Particle Counter (PMS model CSASP-100_HV) placed on one oft the mast of S/Y Oceania. Measurements were performed on five different levels around sea level: 8, 11, 14, 17 and 20 meters. Based on the averaged vertical concentration, profiles were calculated, using Monin-Obuchow theory, vertical sea spray fluxes in the near water layer. Based on fluxes calculated from vertical concentration profiles was calculated sea salt source function over the Baltic Sea. This function gives emission for different particle size, depending on environmental parameters. Emission of sea spray depends of the size of energy lost by the wind waves in process of collapse. Acknowledgements: The support for this study was provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk founded by European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09.

  11. Experiencing the Full Research Process at Sea Education Association (SEA)

    Science.gov (United States)

    Harris, S. E.; Joyce, P.; Jaroslow, G.; Graziano, L.; Lea, C.; Witting, J.; Bower, A.

    2003-12-01

    While some undergraduate research experiences include only a small piece of the research process, students attending Sea Education Association's SEA Semester complete all aspects of oceanographic research in an intensive 12 week program that earns a full semester's credit. In the first half of the program, students read and discuss background literature on a subject, ask questions, pose hypotheses, and develop a written research proposal, which they defend orally. The second half of the course takes place at sea on one of SEA's state-of-the-art oceanographic research vessels where students carry out their sampling plans, analyze samples and data, write a final paper and present their results before the vessel reaches port, completing the course. At sea, students participate in sample collection and analysis for all student projects in addition to learning the general oceanography along their cruise track. This structure exposes students to the realities of research from start to finish and allows them to take full ownership of their projects. In addition to honing writing, public speaking, and problem-solving skills, students learn that research requires dedication, flexibility, and creativity, particularly when their results are unexpected or negate their hypothesis. SEA's undergraduate research program has been developing since 1971. Over that time, SEA has collected an extensive historical oceanographic database in the western Atlantic and Caribbean, plus Pacific data since 2001. This database is available to both students and outside research scientists. Collaborations with scientists outside SEA enhance the student experience and help facilitate oceanographic research by providing "ship-of-opportunity" sampling in remote locations. SEA Semester provides an excellent model for undergraduate research experiences with over 5000 alumni, about 30% of whom enter graduate school. About half the students in SEA's undergraduate programs are non-science majors. Although

  12. Tidal hydrodynamics under future sea level rise and coastal morphology in the Northern Gulf of Mexico

    Science.gov (United States)

    Passeri, Davina L.; Hagen, Scott C.; Plant, Nathaniel G.; Bilskie, Matthew V.; Medeiros, Stephen C.; Alizad, Karim

    2016-05-01

    This study examines the integrated influence of sea level rise (SLR) and future morphology on tidal hydrodynamics along the Northern Gulf of Mexico (NGOM) coast including seven embayments and three ecologically and economically significant estuaries. A large-domain hydrodynamic model was used to simulate astronomic tides for present and future conditions (circa 2050 and 2100). Future conditions were simulated by imposing four SLR scenarios to alter hydrodynamic boundary conditions and updating shoreline position and dune heights using a probabilistic model that is coupled to SLR. Under the highest SLR scenario, tidal amplitudes within the bays increased as much as 67% (10.0 cm) because of increases in the inlet cross-sectional area. Changes in harmonic constituent phases indicated that tidal propagation was faster in the future scenarios within most of the bays. Maximum tidal velocities increased in all of the bays, especially in Grand Bay where velocities doubled under the highest SLR scenario. In addition, the ratio of the maximum flood to maximum ebb velocity decreased in the future scenarios (i.e., currents became more ebb dominant) by as much as 26% and 39% in Weeks Bay and Apalachicola, respectively. In Grand Bay, the flood-ebb ratio increased (i.e., currents became more flood dominant) by 25% under the lower SLR scenarios, but decreased by 16% under the higher SLR as a result of the offshore barrier islands being overtopped, which altered the tidal prism. Results from this study can inform future storm surge and ecological assessments of SLR, and improve monitoring and management decisions within the NGOM.

  13. Sulfur cycling of intertidal Wadden Sea sediments (Konigshafen, Island of Sylt, Germany): sulfate reduction and sulfur gas emission

    Science.gov (United States)

    Kristensen, E.; Bodenbender, J.; Jensen, M. H.; Rennenberg, H.; Jensen, K. M.

    2000-05-01

    Sulfate reduction rates (SRR t) and reduced inorganic sulfur pools (RIS) in Wadden Sea sediment as well as sulfur gas emissions directly to the atmosphere were measured at intervals of 2 to 12 months from 1991 to 1994. Three stations were chosen in the intertidal embayment, Königshafen, representing the range of sediments found in the Wadden Sea: Organic-poor coarse sand, organic-poor and Arenicola marina inhabited medium sand, and organic-rich muddy sand. Maximum SRR t were 2 to 5 times higher in muddy sand than in the sandy sediments. The depth-integrated SRR t varied 12 to 13-fold on a seasonal basis at the three stations. Although temperature controls biochemical processes, the overall control is more complex due to the simultaneous influence of other seasonal factors such as availability of organic matter and oxidation level of surface sediment. The sedimentary RIS pools were low due to iron limitation and contained only 30% acid volatile sulfur (AVS). Muddy sand had up to an order of magnitude more RIS than the two sandy sediments. The turnover of RIS was rapid (turnover time from ˜1 to 32 h), fastest during summer and at the sandy stations. The emission of S-gases was dominated by H 2S during summer (45-67% of the total), and was highest in muddy and lowest in coarse sand. H 2S was less important in early spring (3-49% of the total). Other sulfur gases, such as COS, DMS and CS 2, each accounted for less than 20% of the total sulfur emissions with no specific temporal and spatial pattern. Due to the low content of metals in the sediment, the reduced sulfur pools are cycled rapidly with chemical and biological reoxidation at oxic-anoxic boundaries as a major sink. Thus, the emissions of H 2S account for less than 1‰ of the sulfide produced.

  14. Waves in the seas

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    or change. If ini- tially, only a thin layer of air close to the water surface matters in the mo- mentum transfer from wind to water, afterwards with strong winds, a layer of air upto say 15 to 30 metres comes Small sand waves formed on a seashore due... it breaks with a heading wind or on a beach). Consider an open sea of say 1000 square kilometres wherein billions of 'pushes' and 'pulls' happen over tens of hours, causing uncountable number of waves and wave groups of various types moving in different...

  15. Polarimetric signatures of sea ice in the Greenland Sea

    DEFF Research Database (Denmark)

    Skriver, Henning; Pedersen, Leif Toudal

    1995-01-01

    Polarimetric SAR data of sea ice have been acquired by the Danish polarimetric SAR (EMISAR) during a mission at the Greenland Sea in August 1994. Video recordings from a low-altitude acquisition have been used for interpretation of the SAR data. Also, ERS-1 SAR data and NOAA AVHRR-data have been...

  16. NOAA NDBC SOS - sea_floor_depth_below_sea_surface

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA NDBC SOS server is part of the IOOS DIF SOS Project. The stations in this dataset have sea_floor_depth_below_sea_surface data. Because of the nature of SOS...

  17. EASE-Grid Sea Ice Age

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides weekly estimates of sea ice age for the Arctic Ocean from remotely sensed sea ice motion and sea ice extent. The ice age data are derived from...

  18. Sea modeling and rendering

    Science.gov (United States)

    Cathala, Thierry; Latger, Jean

    2010-10-01

    More and more defence and civil applications require simulation of marine synthetic environment. Currently, the "Future Anti-Surface-Guided-Weapon" (FASGW) or "anti-navire léger" (ANL) missile needs this kind of modelling. This paper presents a set of technical enhancement of the SE-Workbench that aim at better representing the sea profile and the interaction with targets. The operational scenario variability is a key criterion: the generic geographical area (e.g. Persian Gulf, coast of Somalia,...), the type of situation (e.g. peace keeping, peace enforcement, anti-piracy, drug interdiction,...)., the objectives (political, strategic, or military objectives), the description of the mission(s) (e.g. antipiracy) and operation(s) (e.g. surveillance and reconnaissance, escort, convoying) to achieve the objectives, the type of environment (Weather, Time of day, Geography [coastlines, islands, hills/mountains]). The paper insists on several points such as the dual rendering using either ray tracing [and the GP GPU optimization] or rasterization [and GPU shaders optimization], the modelling of sea-surface based on hypertextures and shaders, the wakes modelling, the buoyancy models for targets, the interaction of coast and littoral, the dielectric infrared modelling of water material.

  19. Modelling sea ice dynamics

    Science.gov (United States)

    Murawski, Jens; Kleine, Eckhard

    2017-04-01

    Sea ice remains one of the frontiers of ocean modelling and is of vital importance for the correct forecasts of the northern oceans. At large scale, it is commonly considered a continuous medium whose dynamics is modelled in terms of continuum mechanics. Its specifics are a matter of constitutive behaviour which may be characterised as rigid-plastic. The new developed sea ice dynamic module bases on general principles and follows a systematic approach to the problem. Both drift field and stress field are modelled by a variational property. Rigidity is treated by Lagrangian relaxation. Thus one is led to a sensible numerical method. Modelling fast ice remains to be a challenge. It is understood that ridging and the formation of grounded ice keels plays a role in the process. The ice dynamic model includes a parameterisation of the stress associated with grounded ice keels. Shear against the grounded bottom contact might lead to plastic deformation and the loss of integrity. The numerical scheme involves a potentially large system of linear equations which is solved by pre-conditioned iteration. The entire algorithm consists of several components which result from decomposing the problem. The algorithm has been implemented and tested in practice.

  20. SeaPort-e Workshop

    Science.gov (United States)

    2014-08-01

    aquilent.com 22 QUESTIONS?? 23 Back-up 24 Program Evolution Category SeaPort Original (2001 – 2004) SeaPort-Enhanced (2004...Function = Industry User Function External System Interfaces: Create Purchase Request (Navy ERP ) Receive CAR Data (FPDS-NG) Receive Award Documents (EDA) Receive Award Data (SPS)

  1. Her Husband Is at Sea

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    Out in the sea of China are Chinese offshore oil workers. They battle against wind, waves, loneliness and monotony. Their profession requires not only bravery and endurance from the employees themselves, but also from their spouses. It is because of the wives’support that the husbands can work at sea. This,for women, means double family responsibilities, loneliness, worries and endless waiting.

  2. The Law of the Sea

    Science.gov (United States)

    Levy, Jean-Pierre

    1978-01-01

    Recounts problems related to the law of the sea and suggests that these problems could be dealt with in the classroom in an interdisciplinary manner. Problems include pollution control, fishing rights, development of deep sea mineral deposits, and shore access. (Author/DB)

  3. Plastic in North Sea Fish

    NARCIS (Netherlands)

    Foekema, E.M.; Gruijter, de C.; Mergia, M.T.; Franeker, van J.A.; Murk, A.J.; Koelmans, A.A.

    2013-01-01

    To quantify the occurrence of ingested plastic in fish species caught at different geographical positions in the North Sea, and to test whether the fish condition is affected by ingestion of plastics, 1203 individual fish of seven common North Sea species were investigated: herring, gray gurnard, wh

  4. Sea level and climate variations

    NARCIS (Netherlands)

    Oerlemans, J.

    1985-01-01

    Review paper, ESA Symposium on Application of Satellite Data to Climate Modelling. Alpbach (Austria) Sea level is an essential component of the climate system, on which many human activities in the coastal zone depend. Climate variations leading to changes in relative sea level are

  5. The environmental state at sea

    NARCIS (Netherlands)

    Tatenhove, van J.P.M.

    2016-01-01

    Seas and oceans are confronted with a plethora of environmental problems, caused by land-based activities (agriculture, industries, and ports) and by maritime activities (such as shipping, fishing, oil and gas drilling, tourism, and navigational dredging). Environmental problems at sea challenge the

  6. Sea Level Rise Data Discovery

    Science.gov (United States)

    Quach, N.; Huang, T.; Boening, C.; Gill, K. M.

    2016-12-01

    Research related to sea level rise crosses multiple disciplines from sea ice to land hydrology. The NASA Sea Level Change Portal (SLCP) is a one-stop source for current sea level change information and data, including interactive tools for accessing and viewing regional data, a virtual dashboard of sea level indicators, and ongoing updates through a suite of editorial products that include content articles, graphics, videos, and animations. The architecture behind the SLCP makes it possible to integrate web content and data relevant to sea level change that are archived across various data centers as well as new data generated by sea level change principal investigators. The Extensible Data Gateway Environment (EDGE) is incorporated into the SLCP architecture to provide a unified platform for web content and science data discovery. EDGE is a data integration platform designed to facilitate high-performance geospatial data discovery and access with the ability to support multi-metadata standard specifications. EDGE has the capability to retrieve data from one or more sources and package the resulting sets into a single response to the requestor. With this unified endpoint, the Data Analysis Tool that is available on the SLCP can retrieve dataset and granule level metadata as well as perform geospatial search on the data. This talk focuses on the architecture that makes it possible to seamlessly integrate and enable discovery of disparate data relevant to sea level rise.

  7. Scaling the Baltic Sea environment

    DEFF Research Database (Denmark)

    Larsen, Henrik Gutzon

    2008-01-01

    The Baltic Sea environment has since the early 1970s passed through several phases of spatial objectification in which the ostensibly well-defined semi-enclosed sea has been framed and reframed as a geographical object for intergovernmental environmental politics. Based on a historical analysis...

  8. Downward particle flux and carbon export in the Beaufort Sea, Arctic Ocean; the Malina experiment

    Science.gov (United States)

    Miquel, J.-C.; Gasser, B.; Martín, J.; Marec, C.; Babin, M.; Fortier, L.; Forest, A.

    2015-01-01

    As part of the international, multidisciplinary project Malina, downward particle fluxes were investigated by means of a drifting multi-sediment trap mooring deployed at three sites in the Canadian Beaufort Sea in late summer 2009. Mooring deployments lasted for 28-50 h and targeted the shelf-break and the slope along the Beaufort-Mackenzie continental margin, as well as the edge between the Mackenzie Shelf and the Amundsen Gulf. Besides analyses of C and N, the collected material was investigated for pigments, phyto- and microzooplankton, faecal pellets and swimmers. The measured fluxes were relatively low, in the range of 11-54 mg m-2 d-1 for the total mass, 1-15 mg C m-2 d-1 for organic carbon and 0.2-2.5 mg N m-2 d-1 for nitrogen. Comparison with a long-term trap dataset from the same sampling area showed that the short-term measurements were at the lower end of the high variability characterizing a rather high flux regime during the study period. The sinking material consisted of aggregates and particles that were characterized by the presence of hetero- and autotrophic microzooplankters and diatoms and by the corresponding pigment signatures. Faecal pellets contribution to sinking carbon flux was important, especially at depth where they represented up to 25% of the total carbon flux. The vertical distribution of different morphotypes of pellets showed a marked pattern with cylindrical faeces (produced by calanoid copepods) present mainly within the euphotic zone, whereas elliptical pellets (produced mainly by smaller copepods) were more abundant at mesopelagic depths. These features, together with the density of matter within the pellets, highlighted the role of the zooplankton community in the transformation of carbon issued from the primary production and the transition of that carbon from the productive surface zone to the Arctic Ocean's interior. Our data indicate that sinking carbon flux in this late summer period is primarily the result of a

  9. Downward particle flux and carbon export in the Beaufort Sea, Arctic Ocean; the role of zooplankton

    Science.gov (United States)

    Miquel, J.-C.; Gasser, B.; Martín, J.; Marec, C.; Babin, M.; Fortier, L.; Forest, A.

    2015-08-01

    As part of the international, multidisciplinary project Malina, downward particle fluxes were investigated by means of a drifting multi-sediment trap mooring deployed at three sites in the Canadian Beaufort Sea in late summer 2009. Mooring deployments lasted between 28 and 50 h and targeted the shelf-break and the slope along the Beaufort-Mackenzie continental margin, as well as the edge between the Mackenzie Shelf and the Amundsen Gulf. Besides analyses of C and N, the collected material was investigated for pigments, phyto- and microzooplankton, faecal pellets and swimmers. The measured fluxes were relatively low, in the range of 11-54 mg m-2 d-1 for the total mass, 1-15 mg C m-2 d-1 for organic carbon and 0.2-2.5 mg N m-2 d-1 for nitrogen. Comparison with a long-term trap data set from the same sampling area showed that the short-term measurements were at the lower end of the high variability characterizing a rather high flux regime during the study period. The sinking material consisted of aggregates and particles that were characterized by the presence of hetero- and autotrophic microzooplankters and diatoms and by the corresponding pigment signatures. Faecal pellets contribution to sinking carbon flux was important, especially at depths below 100 m, where they represented up to 25 % of the total carbon flux. The vertical distribution of different morphotypes of pellets showed a marked pattern with cylindrical faeces (produced by calanoid copepods) present mainly within the euphotic zone, whereas elliptical pellets (produced mainly by smaller copepods) were more abundant at mesopelagic depths. These features, together with the density of matter within the pellets, highlighted the role of the zooplankton community in the transformation of carbon issued from the primary production and the transition of that carbon from the productive surface zone to the Arctic Ocean's interior. Our data indicate that sinking carbon flux in this late summer period is primarily

  10. Highly variable Pliocene sea surface conditions in the Norwegian Sea

    Directory of Open Access Journals (Sweden)

    P. E. Bachem

    2017-09-01

    Full Text Available The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial–interglacial variability. Here, we present high-resolution records of sea surface temperature (SST and ice-rafted debris (IRD in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 °C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere glaciation. Cooling from 4.5 to 4.3 Ma may be linked to the onset of poleward flow through the Bering Strait. This cooling was further intensified by a period of cool summers due to weak obliquity forcing. A 7 °C warming of the Norwegian Sea at 4.0 Ma suggests a major increase in northward heat transport from the North Atlantic, leading to an enhanced zonal SST gradient in the Nordic Seas, which may be linked to the expansion of sea ice in the Arctic and Nordic Seas. A warm Norwegian Sea and enhanced zonal temperature gradient between 4.0 and 3.6 Ma may have been a priming factor for increased glaciation around the Nordic Seas due to enhanced evaporation and precipitation at high northern latitudes.

  11. Chartering the high seas

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Far from being a standard exercise, the transportation of coal by sea involves different players and procedures depending on the buyers and the sellers own strategy. This article, extracted from a new report by Drewry Shipping Consultants, identifies the strategies of the main players in the seaborne coal trade. In the coking coal market there is a long established preference for direct producer consumer purchase contracts, with the buyer undertaking the trading function, rather than purchasing through third parties. However, trading companies play a more important role in the steam coal market, acting either as principals or agents - or in some cases both. Both steam and coking coal are contracted mainly on a long-term basis. This guarantees supplies form sources which offer the optimum grades of coal for their plant. Diversity of supply is also an issue in case there are problems in obtaining the chosen coal. Shipping practices in Japan, Europe and elsewhere are examined. 2 figs., 3 tabs.

  12. Arctic Sea Ice Predictability and the Sea Ice Prediction Network

    Science.gov (United States)

    Wiggins, H. V.; Stroeve, J. C.

    2014-12-01

    Drastic reductions in Arctic sea ice cover have increased the demand for Arctic sea ice predictions by a range of stakeholders, including local communities, resource managers, industry and the public. The science of sea-ice prediction has been challenged to keep up with these developments. Efforts such as the SEARCH Sea Ice Outlook (SIO; http://www.arcus.org/sipn/sea-ice-outlook) and the Sea Ice for Walrus Outlook have provided a forum for the international sea-ice prediction and observing community to explore and compare different approaches. The SIO, originally organized by the Study of Environmental Change (SEARCH), is now managed by the new Sea Ice Prediction Network (SIPN), which is building a collaborative network of scientists and stakeholders to improve arctic sea ice prediction. The SIO synthesizes predictions from a variety of methods, including heuristic and from a statistical and/or dynamical model. In a recent study, SIO data from 2008 to 2013 were analyzed. The analysis revealed that in some years the predictions were very successful, in other years they were not. Years that were anomalous compared to the long-term trend have proven more difficult to predict, regardless of which method was employed. This year, in response to feedback from users and contributors to the SIO, several enhancements have been made to the SIO reports. One is to encourage contributors to provide spatial probability maps of sea ice cover in September and the first day each location becomes ice-free; these are an example of subseasonal to seasonal, local-scale predictions. Another enhancement is a separate analysis of the modeling contributions. In the June 2014 SIO report, 10 of 28 outlooks were produced from models that explicitly simulate sea ice from dynamic-thermodynamic sea ice models. Half of the models included fully-coupled (atmosphere, ice, and ocean) models that additionally employ data assimilation. Both of these subsets (models and coupled models with data

  13. Sea Surface Temperature Climate Data Record for the North Sea and Baltic Sea

    DEFF Research Database (Denmark)

    Høyer, Jacob L.; Karagali, Ioanna

    2016-01-01

    A 30-yr climate data record (CDR) of sea surface temperature (SST) has been produced with daily gap-free analysis fields for the North Sea and the Baltic Sea region from 1982 to 2012 by combining the Pathfinder AVHRR satellite data record with the Along-Track Scanning Radiometer (ATSR) Reprocessing...... observations on average. Validation against independent in situ observations shows a very stable performance of the data record, with a mean difference of -0.06 °C compared to moored buoys and a 0.46 °C standard deviation of the differences. The mean annual biases of the SST CDR are small for all years......, with a negligible temporal trend when compared against drifting and moored buoys. Analysis of the SST CDR reveals that the monthly anomalies for the North Sea, the Danish straits, and the central Baltic Sea regions show a high degree of correlation for interannual and decadal time scales, whereas the monthly...

  14. Role of sea ice in air-sea exchange and its relation to sea fog

    Institute of Scientific and Technical Information of China (English)

    解思梅; 包澄澜; 姜德中; 邹斌

    2001-01-01

    Synchronous or quasi-synchronous stereoscopic sea-ice-air comprehensive observation was conducted during the First China Arctic Expedition in summer of 1999. Based on these data, the role of sea ice in sea-air exchange was studied. The study shows that the kinds, distribution and thickness of sea ice and their variation significantly influence the air-sea heat exchange. In floating ice area, the heat momentum transferred from ocean to atmosphere is in form of latent heat; latent heat flux is closely related to floating ice concentration; if floating ice is less, the heat flux would be larger. Latent heat flux is about 21 23.6 W*m-2, which is greater than sensible heat flux. On ice field or giant floating ice, heat momentum transferred from atmosphere to sea ice or snow surface is in form of sensible heat. In the floating ice area or polynya, sea-air exchange is the most active, and also the most sensible for climate. Also this area is the most important condition for the creation of Arctic vapor fog. The heat exchange of a large-scale vapor fog process of about 500000 km2 on Aug. 21 22,1999 was calculated; the heat momentum transferred from ocean to air was about 14.8×109 kW. There are various kinds of sea fog, radiation fog, vapor fog and advection fog, forming in the Arctic Ocean in summer. One important cause is the existence of sea ice and its resultant complexity of both underlying surface and sea-air exchange.

  15. Late Neogene shift from polythermal to cold polar conditions of the Antarctic ice sheet indicated by glacial stratigraphy and sea-ice history

    Science.gov (United States)

    Harwood, D.; Hambrey, M.; McKelvey, B.; Webb, P.; Whitehead, J.

    2003-04-01

    distance greater than 600 km during the Neogene, from a position on the continental shelf edge in Prydz Bay to the inner reaches of the Lambert/Amery Embayment. Glacigene deposits of the Sirius and Pagodroma groups provide direct evidence of the polythermal character of Late Neogene Antarctic ice sheets. The appearance of the modern sea-ice diatom community as dominant elements in marine sediments on the Antarctic shelf may provide the best proxy evidence for dating the transition to the present cold-polar glacial conditions.

  16. Sea surface temperature anomalies in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    . Further analysis has shown that the sea surface anomalies are well correlated to the anomalies of air temperature and latent heat flux values; whereas they are least correlated to the anomalies of wind stress and net radiation values, except over...

  17. Sea otters and Alaska's developing sea farming industry

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The objectives of this paper are to give an overview of the current status of the industry in Alaska, identify potential problems between mariculture and sea otters...

  18. Chemical oceanography of the Arabian Sea Part iv Laccadive sea

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Moraes, C.; Kureishy, T.W.; Sankaranarayanan, V.N.; Jana, T.K.; Naqvi, S.W.A.; Rajagopal, M.D.

    Patterns of distribution of nutrients and nutrients-oxygen relationships are similar to those observed in other parts of the Arabian Sea High magnesium and low fluoride concentrations in the water indicate probable loss of the latter as insoluble ion...

  19. Iridium in sea-water.

    Science.gov (United States)

    Fresco, J; Weiss, H V; Phillips, R B; Askeland, R A

    1985-08-01

    Iridium in sea-water has been measured (after isolation from the saline matrix by reduction with magnesium) by neutron bombardment, radiochemical purification and high-resolution gamma-ray spectroscopy. The concentration obtained in a Pacific coastal water was 1.02 +/- 0.26 x 10(-14) g per g of sea-water. At such extremely low concentrations, seawater is an extremely unlikely source for anomalously high iridium concentrations measured in the Cretaceous-Tertiary boundary layer of deep-sea sediments.

  20. Iridium in sea-water

    Energy Technology Data Exchange (ETDEWEB)

    Fresco, J.; Weiss, H.V.; Phillips, R.B.; Askeland, R.A.

    1985-08-01

    Iridium in sea-water has been measured (after isolation from the saline matrix by reduction with magnesium) by neutron bombardment, radiochemical purification and high resolution ..gamma..-ray spectroscopy. The concentration obtained in a Pacific coastal water was 1.02 +- 0.26 x 10/sup 14/ g per g of sea-water. At such extremely low concentrations, seawater is an extremely unlikely source for anomalously high iridium concentrations measured in the Cretaceous-Tertiary boundary layer of deep-sea sediments.

  1. How SEA can inform lenders

    DEFF Research Database (Denmark)

    Banhalmi-Zakar, Zsuzsa; Larsen, Sanne Vammen

    SEA can be a powerful tool to improve decision-making for plans, policies and programmes, but it can also be a useful for banks. SEA can help lenders address the reputational risks they are exposed to through financing projects that may have a negative impact on the environment and it can also help......, such as in the credit policies. It was also found that in some cases lenders become involved in project planning at a very early stage, when projects are conceptualized, and certainly before formal approval is sought from relevant authorities and an EIA is conducted. This suggests that SEA can be a useful tool...

  2. The politics of SEA indicators

    DEFF Research Database (Denmark)

    Gao, Jingjing; Kørnøv, Lone; Christensen, Per

    2013-01-01

    The use of indicators is not only technical and science-led, but also a value-laden social process, and thus concerns public participation, political judgment and decision-making. This article approaches the Chinese SEA indicator system from a science-policy interface and aims at: 1) contributing...... to the general recognition of indicators functioning at science-policy interfaces in SEA, and 2) analysing, through a Chinese case-study, to what extent national guidelines mediate the science-policy interaction. The overall finding is a strong emphasis on technical/science aspects found in the Chinese SEA...

  3. Summer sea ice characteristics of the Chukchi Sea

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    During August 1999, we investigated sea ice characteristics; its distribution, surface feature, thickness, ice floe movement, and the temperature field around inter-borders of air/ice/seawater in the Chukchi Sea. Thirteen ice cores were drilled at 11 floe stations in the area of 72°24′ 77°18′N, 153°34′ 163°28′W and the ice core structure was observed. From field observation, three melting processes of ice were observed; surface layer melting, surface and bottom layers melting, and all of ice melting. The observation of temperature fields around sea ice floes showed that the bottom melting under the ice floes were important process. As ice floes and open water areas were alternately distributed in summer Arctic Ocean; the water under ice was colder than the open water by 0.4 2.8℃. The sun radiation heated seawater in open sea areas so that the warmer water went to the bottom when the ice floes move to those areas. This causes ice melting to start at the bottom of the ice floes. This process can balance effectively the temperature fluctuating in the sea in summer. From the crystalline structure of sea ice observed from the cores, it was concluded that the ice was composed of ice crystals and brine-ice films. During the sea ice melting, the brine-ice films between ice crystals melted firstly; then the ice crystals were encircled by brine films; the sea ice became the mixture of ice and liquid brine. At the end of melting, the ice crystals would be separated each other, the bond between ice crystals weakens and this leads to the collapse of the ice sheet.

  4. SMOS Sea Surface Salinity Validation in the South China Sea

    Science.gov (United States)

    Ren, Yongzheng; Li, Xiaoming; Dong, Qing

    2013-01-01

    In November 2009, the European Space Agency (ESA) launched the first soil moisture and ocean salinity (SMOS) satellite, which represented the first use of spaceborne remote sensing tools to probe global sea surface salinity (SSS). The SMOS satellite carries a microwave imaging radiometer with aperture synthesis (MIRAS) for detection in the microwave L-band as the only payload. The MIRAS instrument is expected to provide a global SSS distribution with a spatial resolution of approximately 100 km and an accuracy of 0.1-0.2 practical salinity units (psu). The South China Sea is semi-enclosed, and the sea conditions are relatively complex. The suitability of ESA SMOS salinity products for the South China Sea has not been validated. Therefore, using SSS data measured during an expedition in the South China Sea, which was sponsored by China Natural Science Foundation and conducted in the fall of 2011, this paper validated the SSS products released by ESA, which were retrieved using three sea surface roughness models. To analyze the effect of the spatial resolution on the weekly average SMOS SSS distribution, the weekly average salinity data were averaged to reduce the spatial resolution to 0.25 ° x 0.25°. These average data were then compared to the measured data, followed by an analysis of the error variation. In addition, the effects of the orbital track (ascending or descending) on the SSS retrieval were analyzed.

  5. Towards Good Order at Sea

    DEFF Research Database (Denmark)

    Mandrup, Thomas; Vreÿ, Francois

    . The problems originating from the resultant “bad order at sea” can be directly felt on land, when smuggling, terrorism and related criminal activities operate more or less unhindered. The book provides an important mapping of the challenges preventing good order at sea off the African coast and East Africa......This book addresses a timely and important theme in the debate on how to create good governance at sea in general, but specifically in the Western Indian Ocean. In a security milieu where the number of piracy attacks originating from Somalia has decreased, there is an urgent need to address...... structural problems facing attempts to create and maintain good order at sea off East Africa. As mentioned in one of the chapters, the most secure place for a criminal in East Africa to be is at sea, because most African littoral states have only limited capacity to police their territorial waters...

  6. USGS Sea Ice Email Script

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Daily sea ice imagery and charting benefits logistics and navigational planning in the Alaskan Arctic waters, yet access to these data often requires high bandwidth...

  7. Doppler characteristics of sea clutter.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

    Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

  8. A Can of Sea Worms

    Science.gov (United States)

    Zinn, Donald J.

    1977-01-01

    A comprehensive discussion of the free-living worms that inhabit the beaches and subtidal bottoms of the Cape Cod shoreline is presented. Methods for the location, collection, preservation, and identification of sea worms are identified. (BT)

  9. Temperature measurement in the sea

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnamacharyulu, R.J.; Rao, L.V.G.

    ), their advantages and limitations are also touched upon. Calibration of various instruments used for temperature measurement in the sea and the special setup/facilities needed for this purpose are also discussed...

  10. Sea otter studies in Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The final objective of the present Fish and Wildlife sea otter program is to learn enough of the ecology, population, reproductive potential, and requirements in...

  11. Spirulina culture in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Materassi, R.; Tredici, M.; Waldemaro, B.

    1984-01-01

    Laboratory experiments using small raceway ponds have shown that Spirulina maxima can be adapted easily to grow in sea-water supplemented with nitrate, phosphate, bicarbonate, and Fe-EDTA. To prevent precipitate formation, phosphate was supplied by diffusion through a dialysis membrane; the amount of Na-bicarbonate added was low (100 ppm) and the pH was kept in the range 8.6 - 8.8 by bubbling CO/sub 2/ into the culture. No significant differences have been noticed in productivity or in the chemical composition of the biomass between cultures in sea-water and in the standard bicarbonate medium. Cultures subjected to light/dark cycles of 12/12 hours showed a higher respiration rate in sea-water than in the bicarbonate medium. The higher weight loss in the sea-water medium in the dark was counterbalanced by an increased synthesis of carbohydrates during the light period. 9 references.

  12. Black Sea Bass genetic connectivity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Microsatellite analysis of black sea bass was undertaken to determine magnitude and direction of mixing of black seabass across the Hatteras boundary, as well as...

  13. Sea Turtle Acoustic Telemetry Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Acoustic tags were attached to sea turtles captured in various fishing gear and the animals are either actively or passively tracked

  14. Sea bed mapping and inspection

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The conference has 24 presentations on the topics: Sea bed mapping, inspection, positioning, hydrography, marine archaeology, remote operation vehicles and computerized simulation technologies, oil field activities and plans, technological experiences and problems. (tk)

  15. Dynamic Topography of the Bering Sea

    Science.gov (United States)

    2011-01-01

    Bering Sea. Comparisons also indicate that MDT estimates derived from the latest Gravity Recovery and Climate Experiment geoid model have more in common...with the presented sea surface topography than with the MDTs based on earlier versions of the geoid . The presented MDT will increase the accuracy of...estimating the geoid in the Bering Sea. 15. SUBJECT TERMS dynamic topography, sea surface height, Bering Sea, 4DVar 16. SECURITY CLASSIFICATION OF: a

  16. Alien seas oceans in space

    CERN Document Server

    Lopes, Rosaly

    2013-01-01

    In the early days of planetary observation, oceans were thought to exist in all corners of the Solar System. Carbonated seas percolated beneath the clouds of Venus. Features on the Moon's surface were given names such as "the Bay of Rainbows” and the "Ocean of Storms." With the advent of modern telescopes and spacecraft exploration these ancient concepts of planetary seas have been replaced by the reality of something even more exotic. Alien Seas serves up the current research, past beliefs, and new theories to offer a rich array of the "seas" on other worlds. It is organized by location and by the material composing the oceans under discussion, with expert authors penning chapters on their  specialty. Each chapter features new original art depicting alien seas, as well as the latest ground-based and spacecraft images. With the contributors as guides, readers can explore the wild seas of Jupiter's watery satellite Europa, believed similar in composition to battery acid. Saturn's planet-sized moon Titan see...

  17. Sea otter investigation, Amchitka Island, 1954, and proposed plan of research for sea otters

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report describes a sea otter investigation on Amchitka Island during 1954 and a proposed plan of research for sea otters. The report covers capturing wild sea...

  18. Deep-sea Hexactinellida (Porifera) of the Weddell Sea

    Science.gov (United States)

    Janussen, Dorte; Tabachnick, Konstantin R.; Tendal, Ole S.

    2004-07-01

    New Hexactinellida from the deep Weddel Sea are described. This moderately diverse hexactinellid fauna includes 14 species belonging to 12 genera, of which five species and one subgenus are new to science: Periphragella antarctica n. sp., Holascus pseudostellatus n. sp., Caulophacus (Caulophacus) discohexactinus n. sp., C. ( Caulodiscus) brandti n. sp., C. ( Oxydiscus) weddelli n. sp., and C. ( Oxydiscus) n. subgen. So far, 20 hexactinellid species have been reported from the deep Weddell Sea, 15 are known from the northern part and 10 only from here, while 10 came from the southern area, and five of these only from there. However, this apparent high "endemism" of Antarctic hexactinellid sponges is most likely the result of severe undersampling of the deep-sea fauna. We find no reason to believe that a division between an oceanic and a more continental group of species exists. The current poor database indicates that a substantial part of the deep hexactinellid fauna of the Weddell Sea is shared with other deep-sea regions, but it does not indicate a special biogeographic relationship with any other ocean.

  19. Toxic Algae and Early Warning Management in Yellow Sea and Bohai Sea of China

    Institute of Scientific and Technical Information of China (English)

    Song; Lun; Song; Guangjun; Song; Yonggang; Xu; Xiaohong

    2014-01-01

    The research status of toxic algae in Yellow Sea and Bohai Sea are reviewed from the aspects of toxicity characteristics,toxic mechanism and early warning management,and the existing toxic algae and their toxicity in Yellow Sea and Bohai Sea are analyzed in the paper. The early warning level of toxic algae in Yellow Sea and Bohai Sea of China is put forward,and the research direction of shellfish poisoning in future is summarized.

  20. Magnetohydrodynamic sea water propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Petrick, M.; Thomas, A.; Genens, L.; Libera, J.; Nietert, R.; Bouillard, J.; Pierson, E.; Hill, D.; Picologlou, B.; Ohlsson, O.; Kasprzyk, T.; Berry, G.

    1991-01-01

    An experimental and theoretical investigation of a large scale MHD propulsor has been undertaken whose objectives are to (1) investigate the transient and steady state performance of the thruster over operating parameter ranges that are compatible with achievement of high efficiency, (2) to quantify the principal loss mechanisms within the thruster and (3) to obtain preliminary hydroacoustic data. The performance of the thruster was first investigated theoretically with a 3-D code to quantify the loss mechanisms and identify experimental parameter ranges of interest. The loss mechanisms of interest are ohmic losses within the channel and those resulting from electrical currents at the entrance and exit of the thruster, and enhanced frictional losses. The analysis indicated that the relative importance of the loss mechanisms was a function of the thruster design and operating parameters. The experimental investigation of the large scale propulsor is being conducted on a sea water test facility that was designed to match the capabilities of a large 6-T superconducting magnet. The facility design was such that {approximately}90{degrees} of all losses occurred within the propulsion test train (inlet nozzle, propulsor and diffuser) thus facilitating isolation of the loss mechanisms. The test thruster itself is heavily instrumented to provide local measurements of velocity, pressure, and electric fields. The predicted overall thruster performance and value of the loss mechanisms will be compared with measured values. Comparisons will also be presented of the voltage gradients between electrodes, overall thruster efficiency, axial pressure gradients across the propulsor, change in velocity profiles, axial and vertical current distributions and exit distribution of the electrolytic gases.

  1. Magnetohydrodynamic sea water propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Petrick, M.; Thomas, A.; Genens, L.; Libera, J.; Nietert, R.; Bouillard, J.; Pierson, E.; Hill, D.; Picologlou, B.; Ohlsson, O.; Kasprzyk, T.; Berry, G.

    1991-12-31

    An experimental and theoretical investigation of a large scale MHD propulsor has been undertaken whose objectives are to (1) investigate the transient and steady state performance of the thruster over operating parameter ranges that are compatible with achievement of high efficiency, (2) to quantify the principal loss mechanisms within the thruster and (3) to obtain preliminary hydroacoustic data. The performance of the thruster was first investigated theoretically with a 3-D code to quantify the loss mechanisms and identify experimental parameter ranges of interest. The loss mechanisms of interest are ohmic losses within the channel and those resulting from electrical currents at the entrance and exit of the thruster, and enhanced frictional losses. The analysis indicated that the relative importance of the loss mechanisms was a function of the thruster design and operating parameters. The experimental investigation of the large scale propulsor is being conducted on a sea water test facility that was designed to match the capabilities of a large 6-T superconducting magnet. The facility design was such that {approximately}90{degrees} of all losses occurred within the propulsion test train (inlet nozzle, propulsor and diffuser) thus facilitating isolation of the loss mechanisms. The test thruster itself is heavily instrumented to provide local measurements of velocity, pressure, and electric fields. The predicted overall thruster performance and value of the loss mechanisms will be compared with measured values. Comparisons will also be presented of the voltage gradients between electrodes, overall thruster efficiency, axial pressure gradients across the propulsor, change in velocity profiles, axial and vertical current distributions and exit distribution of the electrolytic gases.

  2. Dead sea asphalts: historical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Nissenbaum, A.

    1978-05-01

    Asphalts are present in the Dead Sea basin in three forms: (1) huge blocks, up to 100 tons in weight, composed of extremely pure (>99.99%) solid asphalt occasionally found floating on the lake, (2) veins, seepages, and cavity and fissure fillings in Lower Cretaceous to Holocene rocks, and (3) ozocerite veins on the eastern shore of the lake. Dead Sea asphalts probably have been documented over a longer period of time than any other hydrocarbon deposit--from antiquity to the 19th century. Major uses of asphalt from the Dead Sea have been as an ingredient in the embalming process, for medicinal purposes, for fumigation, and for agriculture. The first known war for control of a hydrocarbon deposit was in the Dead Sea area in 312 B.C. between the Seleucid Syrians and the Nabatean Arabs who lived around the lake. Surface manifestations of asphalt are linked closely to tectonic activity. In the lake itself, the asphalt is associated with diapirs During certain historic periods, tectonic and diapiric activity caused frequent liberation to the Dead Sea surface of semiliquid asphalt associated with large amounts of hydrogen sulfide gas. When the tectonic activity was attenuated, as in the 19th and 20th centuries, the rate of asphalt seepage to the bottom sediments of the Dead Sea was much slower and the asphalt solidified on the lake bottom. The release of asphalt to the surface became much more sporadic, and may have resulted in part from earthquakes. Thus, future asphalt prospecting in the Dead Sea area should be conducted along the boundaries of diapirs or their associated faults.

  3. Integrating out the Dirac sea

    Energy Technology Data Exchange (ETDEWEB)

    Karbstein, Felix

    2009-07-08

    We introduce a new method for dealing with fermionic quantum field theories amenable to a mean-field-type approximation. In this work we focus on the relativistic Hartree approximation. Our aim is to integrate out the Dirac sea and derive a no-sea effective theory'' with positive energy single particle states only. As the derivation of the no-sea effective theory involves only standard Feynman diagrams, our approach is quite general and not restricted to particular space-time dimensions. We develop and illustrate the approach in the ''large N'' limit of the Gross-Neveu model family in 1+1 dimensions. As the Gross-Neveu model has been intensely studied and several analytical solutions are known for this model, it is an ideal testing ground for our no-sea effective theory approach. The chiral Gross-Neveu model, also referred to as 1+1 dimensional Nambu-Jona-Lasinio model, turns out to be of particular interest. In this case, we explicitly derive a consistent effective theory featuring both elementary ''{pi} meson'' fields and (positive energy) ''quark'' fields, starting from a purely fermionic quantum field theory. In the second part of this work, we apply our approach to the Walecka model in 1+1 and 3+1 dimensions. As the Dirac sea caused considerable difficulties in attempts to base nuclear physics on field theoretic models like the Walecka model, mean-field calculations were typically done without the sea. We confront several of these mean-field theory results with our no-sea effective theory approach. The potential of our approach is twofold. While the no-sea effective theory can be utilized to provide new analytical insights in particular parameter regimes, it also sheds new light on more fundamental issues as the explicit emergence of effective, Dirac-sea induced multi-fermion interactions in an effective theory with positive energy states only. (orig.)

  4. Sea Ice Concentration and Extent

    Science.gov (United States)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  5. Sea Ice Concentration and Extent

    Science.gov (United States)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  6. Early Miocene basement clasts in ANDRILL AND-2A core and their implications for paleoenvironmental changes in the McMurdo Sound region (western Ross Sea, Antarctica)

    Science.gov (United States)

    Talarico, Franco M.; Sandroni, Sonia

    2011-07-01

    A detailed provenance study of gravel-size clasts in the lowermost 438 m of the ANDRILL AND-2A core reveals a pattern of dynamic provenance variations which can be discussed for its implications for Early Miocene paleogeographical reconstructions and glaciological models in the McMurdo Sound region (Ross Sea). Clast distribution patterns and distribution of diagnostic basement clast assemblages indicative of three different provenance areas (Mulock-Skelton glacier, Carlyon-Darwin glacier and Koettlitz-Blue glacier regions) can be interpreted in terms of two distinctive ice dynamic scenarios: i) local fluctuations of outlet Transantarctic Mountains glaciers with dominant flows from W to E to the coast (documented in the lowermost core section, at ca. 20.2-20.1 Ma), and ii) larger volume of ice grounded at the regional scale in the Ross Embayment with flow lines running N-S close to the TAM front (in two periods, at ca. 19.7-19.7 Ma and at ca. 17.8-17.4 Ma). Moreover, in core sections including facies typical of open-marine to iceberg-influenced depositional environments, ice-rafted debris compositions reveal that during periods of glacial-minima setting sites of active calving processes dominantly occurred in areas including the present-day Blue-Koettlitz glacier coast, and subordinately in glacier tongues located further south in the Skelton-Mulock glacier area. Consistently with results of numerical modelling the reconstructed glaciological scenarios provide further constraints to paleogeographical reconstructions and glaciological models at the south-western tip of the Ross Sea during significant steps in Antarctic ice sheet evolution through the Early Miocene climatic events.

  7. Iodine emissions from the sea ice of the Weddell Sea

    Directory of Open Access Journals (Sweden)

    H. M. Atkinson

    2012-05-01

    Full Text Available Iodine compounds were measured above, below and within the sea ice of the Weddell Sea during a cruise in 2009, to elucidate the mechanism of local enhancement and volatilisation of iodine. I2 mixing ratios of up to 12.4 pptv were measured 10 m above the sea ice, and up to 31 pptv was observed above surface snow on the nearby Brunt Ice Shelf – large amounts. Atmospheric IO of up to 7 pptv was measured from the ship, and the average sum of HOI and ICl was 1.9 pptv. These measurements confirm the Weddell Sea as an iodine hotspot. Average atmospheric concentrations of CH3I, C2H5I, CH2ICl, 2-C3H7I, CH2IBr and 1-C3H7I were each 0.2 pptv or less. On the Brunt Ice Shelf, enhanced concentrations of CH3I and C2H5I (up to 0.5 and 1 pptv, respectively were observed in firn air, with a diurnal profile that suggests the snow may be a source. In the sea ice brine, iodocarbons concentrations were over 10 times those of the sea water below. The sum of iodide + iodate was depleted in sea ice samples, suggesting some missing iodine chemistry. Flux calculations suggest I2 dominates the iodine atom flux to the atmosphere, but models cannot reconcile the observations and suggest either a missing iodine source or other deficiencies in our understanding of iodine chemistry. The observation of new particle formation, consistent with the model predictions, strongly suggests an iodine source. This combined study of iodine compounds is the first of its kind in this unique region of sea ice rich in biology and rich in iodine chemistry.

  8. Iodine emissions from the sea ice of the Weddell Sea

    Directory of Open Access Journals (Sweden)

    H. M. Atkinson

    2012-11-01

    Full Text Available Iodine compounds were measured above, below and within the sea ice of the Weddell Sea during a cruise in 2009, to make progress in elucidating the mechanism of local enhancement and volatilisation of iodine. I2 mixing ratios of up to 12.4 pptv were measured 10 m above the sea ice, and up to 31 pptv was observed above surface snow on the nearby Brunt Ice Shelf – large amounts. Atmospheric IO of up to 7 pptv was measured from the ship, and the average sum of HOI and ICl was 1.9 pptv. These measurements confirm the Weddell Sea as an iodine hotspot. Average atmospheric concentrations of CH3I, C2H5I, CH2ICl, 2-C3H7I, CH2IBr and 1-C3H7I were each 0.2 pptv or less. On the Brunt Ice Shelf, enhanced concentrations of CH3I and C2H5I (up to 0.5 and 1 pptv respectively were observed in firn air, with a diurnal profile that suggests the snow may be a source. In the sea ice brine, iodocarbons concentrations were over 10 times those of the sea water below. The sum of iodide + iodate was depleted in sea ice samples, suggesting some missing iodine chemistry. Flux calculations suggest I2 dominates the iodine atom flux to the atmosphere, but models cannot reconcile the observations and suggest either a missing iodine source or other deficiencies in our understanding of iodine chemistry. The observation of new particle formation, consistent with the model predictions, strongly suggests an iodine source. This combined study of iodine compounds is the first of its kind in this unique region of sea ice rich in biology and rich in iodine chemistry.

  9. Alone by the Sea

    Directory of Open Access Journals (Sweden)

    Zoran Ferić

    2015-06-01

    Full Text Available 1.At first the island is just a sign on a yellow board with a drawing of a vessel and the letters saying “Car Ferry,” then it is a grayish silhouette in the blue of the sea, and then, later still, an acquaintance working on the ferry, who just nods briefly in greeting. Jablanac, ferry port, its pleasant lobby, and then, from the upper deck, a giant rock approaching. That is the object of a year-long desire: the moment of stepping off the boat and smelling the rosemary, diesel and sheep droppings, seeing the sharp rocks looking at the Strait of Senj, coarse limestone in sharp opposition to the signs that say: Benvenuti, Welcome, Willkommen!At home, on the terrace, in the shade of the oleander, there’s no wish to eat. Only swimming trunks are put on and then, barefoot, without a towel or sun-tanning lotion, off to the beach.“Why won’t you eat something?” grandma asks.She knows that there’s an exciting world waiting out there, but she knows nothing of the details. All friends went on a boat trip. And suddenly one step from the shade of a path covered with oleanders and acacias leads into the burning sun of the afternoon. The light screams, just like children in the water, just like white objects that radiate as if there are some powerful light bulbs within. The feeling of freedom of someone who has just arrived in a foreign place and can now do anything. There’s no one familiar on the beach, they all got in the boat and left. The seafront leading to the camp is full of people, naked children with dirty faces licking ice cream, young families pushing strollers, groups of teenagers who have just woken up from their last night’s party. But there’s no one that must be greeted. The feeling of freedom that’s at the same time close to death. Suddenly, all paths are open. That there are no obligations or friends waiting, this afternoon, until they come back, is a complete boon.

  10. On The Black Sea Surozhian

    Science.gov (United States)

    Caraivan, Glicherie; Corneliu, Cerchia

    2016-04-01

    Some Black Sea researchers still support the idea of no other connection to the Mediterranean Sea between LGM and Karangatian Stage (Riss - Wurm). We try to clarify the source of these disagreements. C14 AMS age data (HERAS Project) made on undisturbed samples from a new Mamaia drilling hole where compared with the classical Black Sea stratigraphic schemes. A first transgressive event (Zone D) is found between 38.00 - 20.20 m depth. Zone D4 shows a fairly rapid rise of sea level, about 10 m below the present one indicating an inner shelf marine polyhaline environment. AMS age data show 14C ages between 53690 - 47359 y (MIS 1), corresponding to the "Surozhian Beds" of Popov. The "beach rock" from Zone E marks the decrease of the sea level after the maximum reached in Zone D4. Zone E mollusc shells AMS data, indicate 14C ages of 48724 - 44604 y, suggesting a long-time reworked material from the previous D4 zone sediments, and represents the beginning of the "regressive Tarkankutian" sequence.The Last Glacial Maximum (LGM) led to the retreat of the sea level down to about 100 m below the current one (27-17 ky BP), followed by an retreat of the shoreline to the present position. At the beginning of the Holocene - MIS 1 (8408-8132 cal. y BP), Black Sea brackish water level grew rapidly, up to -14 m below the present one (Zone F: 22, 57-20, 20 m). Zone F deposits could be correlated with the Bugazian strata. Then, a continuous rising of the Black Sea level is recorded up to a maximum of -2 m under the present one, about 6789 - 7063 cal. y BP, when a transgressive spurt ("Neolithic transgression") may have taken place. After that, given a weak Danubian sedimentary input, coastal erosion intensified. The coarse sandy sediments were reworked and pushed over the previous peat deposits, and suggest a classical "sedimentary regression", not a sea-level decrease. During the last 1.5 ky, sea level has risen towards the current one. Previous C14 dates from "Karangatian

  11. Vulnerability of marginal seas to sea level rise

    Science.gov (United States)

    Gomis, Damia; Jordà, Gabriel

    2017-04-01

    Sea level rise (SLR) is a serious thread for coastal areas and has a potential negative impact on society and economy. SLR can lead for instance to land loss, beach reduction, increase of the damage of marine storms on coastal infrastructures and to the salinization of underground water streams. It is well acknowledged that future SLR will be inhomogeneous across the globe, with regional differences of up to 100% with respect to global mean sea level (GMSL). Several studies have addressed the projections of SLR at regional scale, but most of them are based on global climate models (GCMs) that have a relatively coarse spatial resolution (>1°). In marginal seas this has proven to be a strong limitation, as their particular configurations require spatial resolutions that are not reachable by present GCMs. A paradigmatic case is the Mediterranean Sea, connected to the global ocean through the Strait of Gibraltar, a narrow passage of 14 km width. The functioning of the Mediterranean Sea involves a variety of processes including an overturning circulation, small-scale convection and a rich mesoscale field. Moreover, the long-term evolution of Mediterranean sea level has been significantly different from the global mean during the last decades. The observations of present climate and the projections for the next decades have lead some authors to hypothesize that the particular characteristics of the basin could allow Mediterranean mean sea level to evolve differently from the global mean. Assessing this point is essential to undertake proper adaptation strategies for the largely populated Mediterranean coastal areas. In this work we apply a new approach that combines regional and global projections to analyse future SLR. In a first step we focus on the quantification of the expected departures of future Mediterranean sea level from GMSL evolution and on the contribution of different processes to these departures. As a result we find that, in spite of its particularities

  12. GHRSST Level 4 DMI_OI North Sea and Baltic Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis by the Danish...

  13. How SEA can inform lenders

    DEFF Research Database (Denmark)

    Banhalmi-Zakar, Zsuzsa; Larsen, Sanne Vammen

    SEA can be a powerful tool to improve decision-making for plans, policies and programmes, but it can also be a useful for banks. SEA can help lenders address the reputational risks they are exposed to through financing projects that may have a negative impact on the environment and it can also help...... with identifying the financial incentives that ‘green’ projects attract. Although bank lending decisions apply to projects, examination of the lending practices of an Australian and a Hungarian bank have shown that decisions about the type of projects to target or avoid are also made at strategic level......, such as in the credit policies. It was also found that in some cases lenders become involved in project planning at a very early stage, when projects are conceptualized, and certainly before formal approval is sought from relevant authorities and an EIA is conducted. This suggests that SEA can be a useful tool...

  14. Coccidioidomycosis in southern sea otters

    Science.gov (United States)

    Thomas, Nancy J.; Pappagianis, Demosthenes; Creekmore, Lynn H.; Duncan, Ruth M.

    1994-01-01

    Disseminated coccidioidomycosis was diagnosed postmortem in six southern sea otters (Enhydra lutris nereis) found dying or dead along the Pacific Coast of California at San Luis Obispo County.  These otters were found during winter or summer 1992, 1993, and 1994.  Coccidioides immitis was identified by its morphology in tissue impression smears and by histopathology, and was confirmed by culture.  Positive serologic results were obtained from four of five sea otters tested.  The lungs, pleura, tracheobronchial lymph nodes, liver, and spleen were involved in each case.  There was meningeal involvement in half of the affected animals.  Coccidioidomycosis has been reported in a wild sea otter only once previously, in 1976, and that otter was also found on the coast of San Luis Obispo County.

  15. Mapping the deep sea floor

    DEFF Research Database (Denmark)

    Nielsen, Kristian Hvidtfelt

    By the early 20th century, oceanographers intensified their efforts to map the deep sea. The great depth of the Philippine Trench was first observed by the German Planet Expedition in 1912. During World War II, the US naval vessel Cape Johnson used directional echo-sounding to obtain a depth of 10......,497 m. In 1951, the Danish Galathea Deep Sea Expedition from 1950 to 1952 verified the result of the Cape Johnson sounding. Today, the greatest depth in the Philippine Trench is the Galathea Depth of 10,540 m. The Galathea Expedition produced several echograms of the deepest parts of the Philippine...... Trench in order to map its bathymetric features. The resulting maps are presented in this poster. Unlike many other contemporary developments in deep sea topography and cartography that were shaped by the Cold War, the Galathea maps of the Philippine Trench were intimately connected with the expedition...

  16. EXPERIMENTS OF SEA ICE SIMULATION

    Institute of Scientific and Technical Information of China (English)

    LIU Xi-ying; ZHANG Xue-hong; YU Ru-cong; LIU Hai-long; YU Yong-qiang

    2005-01-01

    As a substitute for the original displaced pole grids, a simple rotated spherical coordinate system was introduced into the Community Sea Ice Model version 4(CSIM4), which is a component of the Community Climate System Model(CCSM) of the American National Center of Atmospheric Research(NCAR), to deal with the "pole problems".In the new coordinates, both the geographical North Pole and South Pole lie in the model equator and grid sizes near the polar region are more uniform.With reanalysis dataset of American National Centers for Environment Prediction(NCEP) and Levitus dataset without considering sub-mixed layer heat flux, the model was integrated for 100 years with thermodynamics process involved only in the former 49 years and both dynamic and thermodynamic processes involved in the left time.Inner consistency of model results was checked with no contradiction found.The results of last 10 years' model output were analyzed and it is shown that the simulated sea ice seasonal variation is rational whereas sea ice extent in the Barents Sea in winter is larger than that of observation.Numerical experiment on influence of sub-mixed layer heat flux was also carried out and it is shown that the sub-mixed layer heat flux can modulate seasonal variation of sea ice greatly.As a model component, the sea ice model with rotated spherical coordinates was coupled with other models (the oceanic general circulation model is the LASG/IAP Climate System Ocean Model(LICOM) with reduced grid, other models are components of NCAR CCSM2) forming a climate system model and its preliminary results were also given briefly.

  17. Black Sea coastal forecasting system

    Directory of Open Access Journals (Sweden)

    A. I. Kubryakov

    2012-03-01

    Full Text Available The Black Sea coastal nowcasting and forecasting system was built within the framework of EU FP6 ECOOP (European COastalshelf sea OPerational observing and forecasting system project for five regions: the south-western basin along the coasts of Bulgaria and Turkey, the north-western shelf along the Romanian and Ukrainian coasts, coastal zone around of the Crimea peninsula, the north-eastern Russian coastal zone and the coastal zone of Georgia. The system operates in the real-time mode during the ECOOP project and afterwards. The forecasts include temperature, salinity and current velocity fields. Ecosystem model operates in the off-line mode near the Crimea coast.

  18. Sailing In Sea of Commerce

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The law of big fish swallowing little fish has expired when it comes to the era of new economy.What prevails nowadays in the sea of commerce is quick fish swallowing slow fish.In the Internet economy,small companies are not destined to lose to giants,but slow ones are doomed to become prey of their quick counterparts. The swiftly rising Yongkang Group has made a breakthrough in dental treatment by translating the law into practice.It is called"Law of the Sea."‘Law of the Sea’

  19. Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19 by multiple Soviet Union institutes (NODC Accession 0077413)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19...

  20. 2010 USGS Lidar: Salton Sea (CA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The USGS Salton Sea project encompasses a 5-kilometer buffer around the Salton Sea, California. Dewberry classified LiDAR for a project boundary that touches 623...

  1. Extended Reconstructed Sea Surface Temperature (ERSST)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Extended Reconstructed Sea Surface Temperature (ERSST) dataset is a global monthly sea surface temperature analysis derived from the International Comprehensive...

  2. Erective Sea Embankment with PCC Piles

    Institute of Scientific and Technical Information of China (English)

    LIU Han-long; FEI Kang; DENG An; ZHANG Ting

    2005-01-01

    The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, this technique integrates PCC pile installation, PVDs drainage systems, and geotextile reinforcements, resulting in sea embankments with PCC piles. In the application of a sea embankment with PCC piles, PCC piles are employed as the retaining structures;the soft sea ground inside PCC piles is drained and improved by PVDs and vacuum-surcharge combined preloading; geotextile-reinforced backfills lying over the improved soft ground form the embankment body. Brief descrptions of the fundamentals, design and construction of the sea embankment with PCC piles are presented. A case study on the stability of sea embankment with PCC piles is presented as well.

  3. Range Extent for southern sea otters 2016

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The GIS shapefile "Range extent of southern sea otters 2016" is a simple polyline representing the geographic distribution of the southern sea otter (Enhydra lutris...

  4. Biogeochemistry of iron in the Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Moffett, J.W.; Vedamati, J.; Goepfert, T.J.; Pratihary, A.K.; Gauns, M.; Naqvi, S.W.A.

    The Arabian Sea is a productive basin where seasonal upwelling and convective mixing result in high surface nutrient concentrations and widespread algal blooms. The factors controlling primary productivity in the Arabian Sea are of interest because...

  5. Quarterly Fishery Surveys - Salton Sea [ds428

    Data.gov (United States)

    California Department of Resources — In the spring of 2003, California Department of Fish and Game (CDFG) personnel began quarterly sampling of Salton Sea fish at fourteen stations around the sea, as...

  6. Implementing the European SEA Directive in planning

    DEFF Research Database (Denmark)

    Kørnøv, Lone

    The paper describes how the European SEA Directive can complement the existing planning practice in Denmark.......The paper describes how the European SEA Directive can complement the existing planning practice in Denmark....

  7. Sea turtles sightings in North Carolina

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea turtles sightings are reported to the NMFS Beaufort Laboratory sea turtle program by the general public as they are fishing, boating, etc. These sightings...

  8. 50 CFR 697.12 - At-sea sea sampler/observer coverage.

    Science.gov (United States)

    2010-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) ATLANTIC COASTAL FISHERIES COOPERATIVE... must: (1) Notify the sea sampler/observer of any sea turtles, marine mammals, or other specimens taken by the vessel. (2) Provide the sea sampler/observer with sea turtles, marine mammals, or...

  9. Estimating sea floor dynamics in the Southern North Sea to improve bathymetric survey planning

    NARCIS (Netherlands)

    Dorst, Leendert Louis

    2009-01-01

    Safe nautical charts require a carefully designed bathymetric survey policy, especially in shallow sandy seas that potentially have dynamic sea floor patterns. Bathymetric resurveying at sea is a costly process with limited resources, though. A pattern on the sea floor known as tidal sand waves is c

  10. Multiscale Models of Melting Arctic Sea Ice

    Science.gov (United States)

    2014-09-30

    1 Multiscale Models of Melting Arctic Sea Ice Kenneth M. Golden University of Utah, Department of Mathematics phone: (801) 581-6851...feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding the evolution of melt ponds and sea...Models of Melting Arctic Sea Ice 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER

  11. [Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].

    Science.gov (United States)

    Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin

    2013-08-01

    The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.

  12. Increased CO2 uptake due to sea ice growth and decay in the Nordic Seas

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Bendtsen, Jørgen; Petersen, L.T.

    2009-01-01

    uptake in the Nordic Seas is currently unknown. We present evidence from 50 localities in the Arctic Ocean that dissolved inorganic carbon is rejected together with brine from growing sea ice and that sea ice melting during summer is rich in carbonates. Model calculations show that melting of sea ice......The uptake rates of atmospheric CO2 in the Nordic Seas are among the highest in the world's oceans. This has been ascribed mainly to a strong biological drawdown, but chemical processes within the sea ice itself have also been suggested to play a role. The importance of sea ice for the carbon...

  13. India and the South China Sea Dispute

    Institute of Scientific and Technical Information of China (English)

    Ma Jiali

    2012-01-01

    South China Sea is a sea area of great significance. It lies between the Pacific and Indian Oceans, a crucial waterway bridging East Asia, Southeast Asia and South Asia. In general, South China Sea is a rich deposit of oil and fishing resources, a transportation hub of strategic importance, and an important buffer zone to safeguard China's maritime rights and interests.

  14. Messinian events in the Black Sea

    NARCIS (Netherlands)

    van Baak, Christiaan G C; Radionova, Eleanora P.; Golovina, Larisa A.; Raffi, Isabella; Kuiper, Klaudia F.; Vasiliev, Iuliana; Krijgsman, Wout

    2015-01-01

    Past hydrological interactions between the Mediterranean Sea and Black Sea are poorly resolved due to complications in establishing a high-resolution time frame for the Black Sea. We present a new greigite-based magnetostratigraphic age model for the Mio-Pliocene deposits of DSDP Hole 380/380A,

  15. 33 CFR 2.22 - Territorial sea.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Territorial sea. 2.22 Section 2... Jurisdictional Terms § 2.22 Territorial sea. (a) With respect to the United States, the following apply— (1) Territorial sea means the waters, 12 nautical miles wide, adjacent to the coast of the United States...

  16. Biogeographic classification of the Caspian Sea

    DEFF Research Database (Denmark)

    Fendereski, F.; Vogt, M.; Payne, Mark

    2014-01-01

    using the Hierarchical Agglomerative Clustering (HAC) method. From an initial set of 12 potential physical variables, 6 independent variables were selected for the classification algorithm, i.e., sea surface temperature (SST), bathymetry, sea ice, seasonal variation of sea surface salinity (DSSS), total...... confirms the relevance of the ecoregions as proxies for habitats with common biological characteristics....

  17. 50 CFR 223.205 - Sea turtles.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Sea turtles. 223.205 Section 223.205... Threatened Marine and Anadromous Species § 223.205 Sea turtles. (a) The prohibitions of section 9 of the Act (16 U.S.C. 1538) relating to endangered species apply to threatened species of sea turtle, except...

  18. Parasites in the Wadden Sea food web

    NARCIS (Netherlands)

    Thieltges, D.W.; Engelsma, M.Y.; Wendling, C.C.; Wegner, M.

    2013-01-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest

  19. Redescription of the sea anemone Bunodeopsis Pelagica

    NARCIS (Netherlands)

    Fisher, Elaine

    1976-01-01

    There are two species of sea anemone occurring on the floating sea weed Sargassum natans in the Caribbean sea: Bunodeopsis pelagica (Quoy & Gaimard) and Anemonia sargassensis Hargitt. The anemones are readily distinguished from one another by their colour and the nature of their tentacles. B.

  20. Parasites in the Wadden Sea food web

    NARCIS (Netherlands)

    Thieltges, D.W.; Engelsma, M.Y.; Wendling, C.C.; Wegner, K.M.

    2013-01-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest

  1. OW NASA SeaWIFS Ocean Color

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset contains satellite-derived sea-surface ocean color (chlorophyll-a) measurements collected by means of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS)...

  2. [Comparative analysis of sea-ice diatom species composition in the seas of Russian Arctic].

    Science.gov (United States)

    Il'iash, L V; Zhitina, L S

    2009-01-01

    Comparative analysis of species composition of ice diatom algae (IDA) of the White, Barents, Kara, Laptev, East Siberian, Chukchi Seas and the Basin of the Arctic Ocean was conducted on the basis of both original and published data. Species composition of IDA counts 567 taxa including 122 centric and 446 pennate diatoms. The freshwater algae composed about 18% of the total species number. In the White Sea, IDA were the most numerous (272 taxa), in the Kara Sea they are the least numerous (57 taxa). The species compositions in different seas differ significantly from each other. Similarity of IDA was consistent with the Arctic Ocean circulation and ice drift. IDA of Chukchi, East Siberian and Laptev Seas are the most similar, as are IDA of White and Kara Seas. Similarity of IDA of Chukchi Sea to those of other seas decrease in the west direction. IDA species differences between regions within one sea could be greater than those between different seas.

  3. Radar for Mapping Sea Ice

    Science.gov (United States)

    Barath, F. T.; Jordan, R. L.

    1983-01-01

    X-band system has 100-m2 resolution. Wide swath imaging radar of synthetic aperature type transmits signal to ground station for subsequent processing into imagery. Concept meets functional requirements for continuously mapping sea ice in north and south polar regions.

  4. Performance and sickness at sea

    NARCIS (Netherlands)

    Bos, J.E.; Bles, W.

    2000-01-01

    Human performance at sea generally decreases with increasing severity of seasickness. Seasickness predictions can be made, be it that motions are assumed to be translational along a vertical axis only and sinusoidal. Here, a deterministic model is presented based on physiological knowledge of the ve

  5. Chicken Porridge with Sea Cucumber

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Main ingredients: 50 grams of chicken breast, 200 grams of gray sea cucumbers Supplementary ingredients: 100 grams of water chestnut, the whites of four eggs, MSG, salt, wine, meat soup, starch, sugar, scallions, ginger, soy sauce Directions: Chop up the chicken breast and water chestnut into small

  6. IAHR List of Sea Parameters

    DEFF Research Database (Denmark)

    Frigaard, Peter; Helm-Petersen, J; Klopman, G.

    1997-01-01

    A Working Group on multidirectional waves formed by the International Association for Hydraulic Research has proposed an update of the IAHR List of Sea State Parameters from 1986 in the part concerning directional. Especially wave structure interaction with reflection of the waves have been treated....

  7. The Sea Ice Board Game

    Science.gov (United States)

    Bertram, Kathryn Berry

    2008-01-01

    The National Science Foundation-funded Arctic Climate Modeling Program (ACMP) provides "curriculum resource-based professional development" materials that combine current science information with practical classroom instruction embedded with "best practice" techniques for teaching science to diverse students. The Sea Ice Board…

  8. Climate change challenges for SEA

    DEFF Research Database (Denmark)

    Larsen, Sanne Vammen

    This paper takes a theoretical perspective on the challenges that climate changes pose for SEA. The theoretical framework used is the sociologist Ulrich Beck’s theory of risk society and the aspects that characterise this society. Climate change is viewed as a risk, and the theory is used to derive...

  9. The Sea Ice Board Game

    Science.gov (United States)

    Bertram, Kathryn Berry

    2008-01-01

    The National Science Foundation-funded Arctic Climate Modeling Program (ACMP) provides "curriculum resource-based professional development" materials that combine current science information with practical classroom instruction embedded with "best practice" techniques for teaching science to diverse students. The Sea Ice Board…

  10. Chaetognatha of the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Achuthankutty, C.T.; Nair, S.R.S.; Madhupratap, M.

    Chaetognatha of the Andaman Sea were studied during 51 and 52 cruises of R.V Gaveshani (Jan to Feb 1979) The area between southeast of Andaman island and north of Nicobar island had relatively higher density Total population of chaetognaths ranged...

  11. Generic Hurricane Extreme Seas State

    DEFF Research Database (Denmark)

    Wehmeyer, Christof; Skourup, Jesper; Frigaard, Peter

    2012-01-01

    the US east coast and the Gulf of Mexico (1851 - 2009) and Japanese east coast (1951 -2009) form the basis for Weibull extreme value analyses to determine return period respective maximum wind speeds. Unidirectional generic sea state spectra are obtained by application of the empirical models...

  12. Meiofauna of the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Parulekar, A.H.

    Total meiofauna of the Andaman Sea, in the depth range 30-2150m was between 68 and 438/10cm2 (X-bar = 247.8). The biomass was within the range 3.57 and 32.8mg/10cm 2 (X-bar = 14.46). faunal components were maximum in sandy sediments which contained...

  13. Past and present Aral Sea

    Science.gov (United States)

    Dukhovniy, Viktor; Stulina, Galina; Eshchanov, Odylbek

    2013-04-01

    The tragedy of disappearing of Aral Sea is well known to the World. Before and after collapse of Soviet Union, a huge quantity of scientific and popular editions described with grief the situation around the Aral Sea. After the NIS states became independent, World Bank, UNDP, UNEP in proper competition with each other had provided some assessment of the situation through presentation of some small and medium grants, but after 2000, the local population remained alone with own problems. Although on the eyes of the present generation a unique transformation of great water body into deserts took place, the global scientific community did not find forces and financing for real and detail investigation of the processes accompanying the Sea shrinking and land formation. We should acknowledge and give big respect to NATO, later to German Government that through GTZ (now GIZ) - German International Collaboration Agency - and GFZ (Potzdam) paid attention to this area of environment crisis and organized scientific and protective design in the so-called Priaralie - the territory around the drying Sea and delta of the two rivers - Amudarya and Syrdarya. Thank to this assistance, the local specialists in collaboration with limited a number of foreign scientists (N.Aladin, P.Zavialov, Joop de Schutter, Hans Wilps, Hedi Oberhansli) organized significant works for detail socioeconomic, ecological and hydrological assessment situation in Priaralie and on the Aral sea coast. On this base, Ministry of Agriculture and Water resources of Uzbekistan and State Committee of Water resources of Kazakhstan developed a plan of rehabilitation of Amudarya and Syrdarya deltas and started implementation of these projects. If Kazakh water authority moved ahead in wetland restoration faster, a forestation of delta and drying bed of Aral Sea got big success in Uzbek territory. 244 thousands hectares of saxsaul and tamarix were planted for protection of the Priaralie. By request of GTZ SIC, ICWC

  14. Salton Sea Ecosystem Monitoring Project

    Science.gov (United States)

    Miles, A. Keith; Ricca, Mark A.; Meckstroth, Anne; Spring, Sarah E.

    2009-01-01

    The Salton Sea is critically important for wintering and breeding waterbirds, but faces an uncertain future due to water delivery reductions imposed by the Interstate and Federal Quantification Settlement Agreement of 2003. The current preferred alternative for wetland restoration at the Salton Sea is saline habitat impoundments created to mitigate the anticipated loss of wetland habitat. In 2006, a 50-hectare experimental complex that consisted of four inter-connected, shallow water saline habitat ponds (SHP) was constructed at the southeastern shoreline of the Salton Sea and flooded with blended waters from the Alamo River and Salton Sea. The present study evaluated ecological risks and benefits of the SHP concept prior to widespread restoration actions. This study was designed to evaluate (1) baseline chemical, nutrient, and contaminant measures from physical and biological constituents, (2) aquatic invertebrate community structure and colonization patterns, and (3) productivity of and contaminant risks to nesting waterbirds at the SHP. These factors were evaluated and compared with those of nearby waterbird habitat, that is, reference sites.

  15. Climate change challenges for SEA

    DEFF Research Database (Denmark)

    Larsen, Sanne Vammen

    This paper takes a theoretical perspective on the challenges that climate changes pose for SEA. The theoretical framework used is the sociologist Ulrich Beck’s theory of risk society and the aspects that characterise this society. Climate change is viewed as a risk, and the theory is used to derive...

  16. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

    Science.gov (United States)

    2015-09-30

    the Arctic Ocean and surrounding seas, with particular emphasis on the Chukchi and Beaufort Seas. Some of the largest changes to the sea ice cover are...Changing Arctic Sea Ice Cover Don Perovich ERDC – CRREL 72 Lyme Road Hanover, NH 03755 Phone: 603-646-4255 Email: donald.k.perovich...quantitative understanding of the partitioning of solar radiation by the Arctic sea ice cover and its impact on the heat and mass balance of the ice and upper

  17. Evidence for the Late Cenozoic Antarctic Ice Sheet evolution and bottom current dynamics in the central-western Ross Sea outer margin, Antarctica

    Science.gov (United States)

    Kim, Sookwan; De Santis, Laura; Kuk Hong, Jong; Cottlerle, Diego; Petronio, Lorenzo; Colizza, Ester; Bergamasco, Andrea; Kim, Young-Gyun; Kang, Seung-Goo; Kim, Hyoungjun; Kim, Suhwan; Wardell, Nigel; Geletti, Riccardo; McKay, Robert; Jin, Young Keun; Kang, Sung-Ho

    2016-04-01

    Sedimentary records in polar continental margins provide clues for understanding paleo-depositional environments, related to ice sheet evolution and bottom-water current dynamics, during times of past climate and global sea level changes. Previous seismostratigraphic studies of the Ross Sea embayment, Antarctica, illustrated its general stratigraphic framework and the distribution of glacial sedimentary features over the continental shelf, since the onset of Antarctic ice-sheets at the Eocene-Oligocene boundary (~34.0 Ma). In contrast, there are a fewer studies for the outer continental margin, where continuous sedimentary deposits generally preserve the record of past climate cycles with minimum hiatus, comparing to the inner- and mid-continental shelf, where grounding ice streams eroded most of the sediments. Here we present a seismostratigraphic analysis of 2-D multichannel seismic reflection profiles, from the Central Basin located in the central-western Ross Sea outer margin. A glacial prograding wedge developed at the mouth of the Joides Basin since early-middle Miocene times (RSU4: ~14.0 Ma). And the Central Basin was filled with stacked debris-flow deposits and turbidites. The sediment depocenter shifted from the Central Basin toward the slope in the Pliocene (after RSU2: ~3.3 Ma). Pliocene foreset beds are steep and pinch out at the base of the continental slope. Bottom current controlled sediment drifts well developed since the middle Miocene, along the western slope of the central Basin and on the basement highs These areas are far from the mouth of the Joides trough, where most of the glacial sediment is deposited, and they are also more elevated than the basinal areas, where gravity flow maximum thickness accumulated. Along the western slope of the central Basin and over the basement highs, the signature in the sediments of the action of bottom current reworking and shaping the sea floor can be then clearly recognized. We present the sediment drifts

  18. Facing up to sea rise.

    Science.gov (United States)

    Pernetta, J

    1994-01-01

    A milder and less extreme climate, abundance of fish and mollusks, transport and communication, and fertile land at low altitudes have drawn humans to coastal areas and river valleys for centuries. More than 60% of the world's population occupy the 150 km closest to the coast. Millions of tourists come to coastlines and small tropical islands for recreation. About 80% of the global fish supply originates from the 19 km closest to the shore. Fish are the only protein source for the rapidly growing populations in many developing countries. Global climate change is increasing the sea level so much that by 2050, the mean increase will be about 38 cm (24-52 cm). The Intergovernmental Panel on Climate Change (IPCC) notes that the effects of sea level rise will differ from place to place. Direct effects are flooding of low-lying coastal areas and increased erosion rates. An indirect effect includes higher water tables and intrusion of saline water into aquifers, resulting in loss of fresh ground water resources. These effects may make coastal areas less suitable for settlement and agriculture. Coral sand settled on top of coral reefs makes up the unstable, small atoll islands of the Pacific and Indian Oceans. People on these islands depend almost entirely on the sea for their livelihood and on the small amount of fresh water with which they grow root crops and drink. Rising sea levels also threaten low lying countries, e.g., Bangladesh, and densely populated deltas, e.g., the Nile. Changes in the frequency and severity of flooding will increase Bangladesh's dependence on foreign aid. IPCC sees 3 possible responses to the rising sea level: defense, retreat, and accommodation. Accommodation is the only practical choice for many developing countries. A switch from rice cultivation to mariculture of prawns and fish is an example of accommodation. We need to more completely understand the natural processes in coastal environments to be better prepared for climate change.

  19. Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian Sea and White Sea from R/Vs Artemovsk, Atlantida, Okeanograf, Professor Rudovits, and ice observations, 1957 - 1995 (NODC Accession 0073674)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian...

  20. Thermal biology of sea snakes and sea kraits.

    Science.gov (United States)

    Heatwole, Harold; Grech, Alana; Monahan, John F; King, Susan; Marsh, Helene

    2012-08-01

    Temperature probably had no direct effect on the evolution of sea kraits within their center of origin, a geologically stable thermal zone straddling the equator, but may have indirectly affected expansions and contractions in distributions beyond that zone through global fluctuations that caused alternation of higher and lower sea levels. The northern limit of the Laticauda colubrina complex seems to be the 20°C isotherm; in the south, the range does not reach that isotherm because there is no land (also a habitat requirement of sea kraits) within the zone of suitable temperature. The relationship of temperature to the pattern of geographic variation in morphology supports either the hypothesis of peripheral convergence or the developmental hypothesis but does not distinguish between them. Quadratic surfaces relating cumulative scores for coloration and morphological characters to global position showed a strong latitudinal component and an even stronger longitudinal one in which the direction of the latitudinal effect was reversed between east and west. A multivariate analysis revealed that while morphological characters vary significantly by location and climate when tested separately, when the influence of location on morphology is taken into account, no residual relationship between climate and morphology remains. Most marine snakes have mean upper temperature tolerances between 39°C and 40°C and operate at temperatures much nearer their upper thermal limits than their lower limits but still avoid deleterious extremes by diving from excessively hot water to deeper, cooler strata, and by surfacing when water is cold. At the surface in still water in sunlight, Pelamis can maintain its body temperature slightly above that of the water, but whether this is significant in nature is questionable. As temperature falls below 18-20°C, survival time is progressively reduced, accompanied by the successive occurrence of cessation of feeding, cessation of swimming, and

  1. Jet formation at the sea ice edge

    Science.gov (United States)

    Feltham, D. L.; Heorton, H. D.

    2014-12-01

    The sea ice edge presents a region of many feedback processes between the atmosphere, ocean and sea ice, which are inadequately represented in current climate models. Here we focus on on-ice atmospheric and oceanic flows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere flowing over, and ocean flowing under, a compacted sea ice edge. We have studied a dynamic sea ice edge responding to atmospheric and oceanic jet formation. The shape and strength of atmospheric and oceanic jets during on-ice flows is calculated from existing studies of the sea ice edge and prescribed to idealised models of the sea ice edge. An idealised analytical model of sea ice drift is developed and compared to a sea ice climate model (the CICE model) run on an idealised domain. The response of the CICE model to jet formation is tested at various resolutions. We find that the formation of atmospheric jets during on-ice winds at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The modelled sea ice edge jet is in agreement with an observed jet although more observations are needed for validation. The increase in ice drift speed is dependent upon the angle between the ice edge and wind and can result in a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation during on-ice currents and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

  2. Global Warming and Caspian Sea Level Fluctuations

    CERN Document Server

    Ardakanian, Reza

    2013-01-01

    Coastal regions have a high social, economical and environmental importance. Due to this importance the sea level fluctuations can have many bad consequences. In this research the correlation between the increasing trend of temperature in coastal stations due to Global Warming and the Caspian Sea level has been established. The Caspian Sea level data has been received from the Jason-1 satellite. It was resulted that the monthly correlation between the temperature and sea level is high and also positive and almost the same for all the stations. But the yearly correlation was negative. It means that the sea level has decreased by the increase in temperature.

  3. Deep-sea fungi: Occurrence and adaptations

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, S.

    in it being the least understood environments on the earth. The understanding of deep sea will unravel a lot of exciting information about the history of life existing on earth. The deep sea was thought to be a very difficult environment for life forms.... Danovaro R, Fabiano M, Della Croce N (1995) Labile organic matter and microbial biomasses in deep-sea sediments (Eastern Mediterranean Sea). Deep-Sea Research I, 40: 953-65. DasSarma S, Arora P (2001) Halophiles. Encyclopedia of Life Sciences. Macmillan...

  4. Ecological consequences of sea-ice decline.

    Science.gov (United States)

    Post, Eric; Bhatt, Uma S; Bitz, Cecilia M; Brodie, Jedediah F; Fulton, Tara L; Hebblewhite, Mark; Kerby, Jeffrey; Kutz, Susan J; Stirling, Ian; Walker, Donald A

    2013-08-02

    After a decade with nine of the lowest arctic sea-ice minima on record, including the historically low minimum in 2012, we synthesize recent developments in the study of ecological responses to sea-ice decline. Sea-ice loss emerges as an important driver of marine and terrestrial ecological dynamics, influencing productivity, species interactions, population mixing, gene flow, and pathogen and disease transmission. Major challenges in the near future include assigning clearer attribution to sea ice as a primary driver of such dynamics, especially in terrestrial systems, and addressing pressures arising from human use of arctic coastal and near-shore areas as sea ice diminishes.

  5. On the Sea, From the Sea, Of the Sea: The Physics of maritime Governance

    Science.gov (United States)

    James, Royce; Page, Eric

    2014-03-01

    The United States Coast Guard Academy Physics Section is proud to present our initial conceptions of ``On the Sea, From the Sea, Of the Sea: The Physics of Maritime Governance,'' a program funded by an APS Outreach Grant in 2013. In our classes, the Physics Section has focused on active student engagement for the past ten years. Recently, we have refined our program to make heavy use of Interactive Lecture Demonstrations (ILDs) and our own highly interactive adaptation which we call Interactive Lecture Labs (ILLs). ``On the Sea'' is a unique opportunity to investigate their use in a different learning modality from our standard college level military academic use. Multigenerational science, technology, engineering, and mathematics (STEM) projects are a prolific source of academic discourse, while learning through play has been touted as an effective learning tool. We plan to investigate group and individual participation, intragroup communication, demographics, and prior skill (or education) in comparison to outcomes in learning objectives through projects designed to educate the Coast Guard Academy and surrounding community on the physics of the Coast Guard's missions. Progress on the lab and demonstration designs, community participation, and our emerging ILL and ILD pedagogical methods, will be reported.

  6. Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

    Science.gov (United States)

    Cronin, Thomas M.; O'Regan, Matt; Pearce, Christof; Gemery, Laura; Toomey, Michael; Semiletov, Igor; Jakobsson, Martin

    2017-09-01

    Deglacial (12.8-10.7 ka) sea level history on the East Siberian continental shelf and upper continental slope was reconstructed using new geophysical records and sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The focus of this study is two cores from Herald Canyon, piston core SWERUS-L2-4-PC1 (4-PC1) and multicore SWERUS-L2-4-MC1 (4-MC1), and a gravity core from an East Siberian Sea transect, SWERUS-L2-20-GC1 (20-GC1). Cores 4-PC1 and 20-GC were taken at 120 and 115 m of modern water depth, respectively, only a few meters above the global last glacial maximum (LGM; ˜ 24 kiloannum or ka) minimum sea level of ˜ 125-130 meters below sea level (m b.s.l.). Using calibrated radiocarbon ages mainly on molluscs for chronology and the ecology of benthic foraminifera and ostracode species to estimate paleodepths, the data reveal a dominance of river-proximal species during the early part of the Younger Dryas event (YD, Greenland Stadial GS-1) followed by a rise in river-intermediate species in the late Younger Dryas or the early Holocene (Preboreal) period. A rapid relative sea level rise beginning at roughly 11.4 to 10.8 ka ( ˜ 400 cm of core depth) is indicated by a sharp faunal change and unconformity or condensed zone of sedimentation. Regional sea level at this time was about 108 m b.s.l. at the 4-PC1 site and 102 m b.s.l. at 20-GC1. Regional sea level near the end of the YD was up to 42-47 m lower than predicted by geophysical models corrected for glacio-isostatic adjustment. This discrepancy could be explained by delayed isostatic adjustment caused by a greater volume and/or geographical extent of glacial-age land ice and/or ice shelves in the western Arctic Ocean and adjacent Siberian land areas.

  7. Sea ice thickness and recent Arctic warming

    Science.gov (United States)

    Lang, Andreas; Yang, Shuting; Kaas, Eigil

    2017-01-01

    The climatic impact of increased Arctic sea ice loss has received growing attention in the last years. However, little focus has been set on the role of sea ice thickness, although it strongly determines surface heat fluxes. Here ensembles of simulations using the EC-Earth atmospheric model (Integrated Forecast System) are performed and analyzed to quantify the atmospheric impacts of Arctic sea ice thickness change since 1982 as revealed by the sea ice model assimilation Global Ice-Ocean Modeling and Assimilation System. Results show that the recent sea ice thinning has significantly affected the Arctic climate, while remote atmospheric responses are less pronounced owing to a high internal atmospheric variability. Locally, the sea ice thinning results in enhancement of near-surface warming of about 1°C per decade in winter, which is most pronounced over marginal sea ice areas with thin ice. This leads to an increase of the Arctic amplification factor by 37%.

  8. Episodic sea-floor spreading in the Southern Red Sea

    Science.gov (United States)

    Almalki, Khalid A.; Betts, Peter G.; Ailleres, Laurent

    2014-03-01

    The Red Sea represents the most spectacular example of a juvenile ocean basin on the modern Earth. Synthesis of regional aeromagnetic data, gravity data, seismic refraction data coupled with structural mapping from the Farasan Islands suggest that the opening of the Red Sea is complex and episodic. Modeling of magnetic and gravity data constrained by seismic refraction data reveals the Arabian Shelf is underlain by oceanic and transitional crust and that mafic diking and intrusions are focused at the continental-transitional crust boundary. This relationship is interpreted to indicate that early Miocene diking along the Arabian Escarpment heralded termination of oceanic basin formation and a shift in the locus of extension focused from a central mid-ocean ridge spreading center to the continental-transitional crust zone. Uplift along the Arabian Escarpment caused erosion and Middle to Late Miocene sedimentation of the Farasan Bank onto existing oceanic crust, suggesting that the extensive sedimentary banks of the southern Red Sea are not passive margins. Re-initiation of spreading occurred at ca 5 Ma. Pliocene to Pleistocene Shelf reef systems (Farasan Islands), developed on the flanks of the spreading ridge, are extensively overprinted by normal faults, suggesting that not all crustal extension is accommodated by active spreading.

  9. Relationship between Hadley circulation and sea ice extent in the Bering Sea

    Institute of Scientific and Technical Information of China (English)

    ZHOU BoTao; WANG HuiJun

    2008-01-01

    The linkage between Hadley circulation (HC) and sea ice extent in the Bering Sea during March-April is investigated through an analysis of observed data in this research. It is found that HC is negatively correlated to the sea ice extent in the Bering Sea, namely, strong (weak) HC is corresponding to less (more) sea ice in the Bering Sea. The present study also addresses the large-scale atmospheric general circulation changes underlying the relationship between HC and sea ice in the Bering Sea. It follows that a positive phase of HC corresponds to westward located Aleutian low, anomalous southerlies over the eastern North Pacific and higher temperature in the Bering Sea, providing unfavorable atmospheric and thermal conditions for the sea ice forming, and thus sea ice extent in the Bering Sea is decreased, and vice versa. In addition, it is further identified that East Asian-North Pacific-North America telecon-nection may play an important role in linking HC and changes of atmospheric circulations as well as sea ice in the Bering Sea.

  10. Micromechanics of Sea Urchin spines.

    Directory of Open Access Journals (Sweden)

    Naomi Tsafnat

    Full Text Available The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine's unique porous structure, based on micro-computed tomography (microCT and incorporating anisotropic material properties, was developed to study its response to mechanical loading. Simulations show that high stress concentrations occur at certain points in the spine's architecture; brittle cracking would likely initiate in these regions. These analyses demonstrate that the organization of single-crystal calcite in the unique, intricate morphology of the sea urchin spine results in a strong, stiff and lightweight structure that enhances its strength despite the brittleness of its constituent material.

  11. Sea Power. Quickscan; Zeekracht. Quickscan

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-08-15

    The Dutch Stichting Natuur en Milieu (The Netherlands Foundation for Nature and Environment - SNM) takes the view that the long time span between application for a permit and the realization of offshore wind parks in the North Sea is the result of unnecessary bureaucracy. Therefore SNM has asked the Kafka Brigade to list the procedures for construction of offshore wind parks in the North Sea that might be causing these delays. [mk]. [Dutch] de Stichting Natuur en Milieu (SNM) is van mening dat de oorzaak van de lange doorlooptijd die ligt tussen het aanvragen van een vergunning en de realisatie van offshore windparken in de Noordzee ligt in de onnodige bureaucratie. SNM heeft daarom de Kafkabrigade gevraagd een inventarisatie te maken van procedures rond het bouwen van offshore windmolenparken in de Noordzee die mogelijk vertragend kunnen werken.

  12. Generic Hurricane Extreme Seas State

    DEFF Research Database (Denmark)

    Wehmeyer, Christof; Skourup, Jesper; Frigaard, Peter

    2012-01-01

    Extreme sea states, which the IEC 61400-3 (2008) standard requires for the ultimate limit state (ULS) analysis of offshore wind turbines are derived to establish the design basis for the conceptual layout of deep water floating offshore wind turbine foundations in hurricane affected areas...... data is required for a type specific conceptual design. ULS conditions for different return periods are developed, which can subsequently be applied in siteindependent analysis and conceptual design. Recordings provided by National Oceanic and Atmospheric Administration (NOAA), of hurricanes along...... for hurricane generates seas by Young (1998, 2003, and 2006), requiring maximum wind speeds, forward velocity and radius to maximum wind speed. An averaged radius to maximum sustained wind speeds, according to Hsu et al. (1998) and averaged forward speed of cyclonic storms are applied in the initial state...

  13. Mind the gap in SEA

    DEFF Research Database (Denmark)

    Larsen, Sanne Vammen; Kørnøv, Lone; Wejs, Anja

    2012-01-01

    and discussed, mainly based on Scott's theory of institutions. The institutional analysis highlights a regulatory element, since the assessment of climate change synergies is underpinned by legislation, but not by guidance. This means that great focus is on normative elements such as the local interpretation...... of legislation and of climate change mitigation and adaptation. The analysis also focuses on how the fragmentation of the organisation in which climate change and SEA are embedded has bearings on both normative and cultural–cognitive elements. This makes the assessment of synergies challenging. The evidence......This article takes its point of departure in two approaches to integrating climate change into Strategic Environmental Assessment (SEA): Mitigation and adaptation, and in the fact that these, as well as the synergies between them and other policy areas, are needed as part of an integrated...

  14. Spatial and Temporal Antarctic Ice Sheet Mass Trends, Glacio-Isostatic Adjustment, and Surface Processes from a Joint Inversion of Satellite Altimeter, Gravity, and GPS Data

    Science.gov (United States)

    Martin-Espanol, Alba; Zammit-Mangion, Andrew; Clarke, Peter J.; Flament, Thomas; Helm, Veit; King, Matt A.; Luthcke, Scott B.; Petrie, Elizabeth; Remy, Frederique; Schon, Nana; hide

    2016-01-01

    We present spatiotemporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003-2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time-invariant solution for glacio-isostatic adjustment while remaining largely independent of forward models. We establish that over the period 2003-2013, Antarctica has been losing mass at a rateof -84 +/- 22 Gt per yr, with a sustained negative mean trend of dynamic imbalance of -111 +/- 13 Gt per yr. West Antarctica is the largest contributor with -112 +/- 10 Gt per yr, mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of -28 +/- 7 Gt per yr and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 +/- 18 Gt per yr in East Antarctica due to a positive trend of surface mass balance anomalies.

  15. Comprehensive spatiotemporal glacier and ice sheet velocity measurements from Landsat 8

    Science.gov (United States)

    Moon, Twila; Fahnestock, Mark; Scambos, Ted; Klinger, Marin; Haran, Terry

    2015-04-01

    Combining newly developed software with Landsat 8 image returns, we are now producing broad-coverage ice velocity measurements on weekly to monthly scales across ice sheets and glaciers. Using new image-to-image cross correlation software, named PyCorr, we take advantage of the improved radiometric resolution of the Landsat 8 panchromatic band to create velocity maps with sub-pixel accuracy. Landsat 8's 12-bit radiometric resolution supports measurement of ice flow in uncrevassed regions based on persistent sastrugi patterns lasting weeks to a few months. We also leverage these improvements to allow for ice sheet surface roughness measurements. Landsat 8's 16-day repeat orbit and increased image acquisition across the Greenland and Antarctic ice sheets supports development of seasonal to annual ice sheet velocity mosaics with full coverage of coastal regions. We also create time series for examining sub-seasonal change with near real time processing in areas such as the Amundsen Sea Embayment and fast flowing Greenland outlet glaciers. In addition, excellent geolocation accuracy enables velocity mapping of smaller ice caps and glaciers, which we have already applied in Alaska and Patagonia. Finally, PyCorr can be used for velocity mapping with other remote sensing imagery, including high resolution WorldView satellite data.

  16. Open Ocean Bilging, Arabian Sea

    Science.gov (United States)

    1989-01-01

    These dual oil slicks on the ocean surface are the result of tanker ships flushing their tanks (bilging) in the Arabian Sea (18.5N, 62.5E). These two ships flushed out their bilges, apparently contaminated with bunker oil, leaving oily residues on the ocean's surface. One wake, believed to have been done earlier than the other, has been broadened by the effects of surface winds and current.

  17. Chicken Porridge with Sea Cucumber

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Chicken Porridge with Sea Cucumber is a dish created according to a well-known story about Jia Chang, who raised cocks during the Tang Dynasty. Cockfighting was popular among commonfolk during the Tang Dynasty. Emperor Xuanzong selected 5,000 cocks in Chang’an, and 500 children to feed them and train them to fight. Jia Chang was one of the children. Sent to the

  18. Coastal and Semi Enclosed Seas

    Science.gov (United States)

    2016-06-07

    Numerical model process and sensitivity studies are conducted to better understand the dynamics and thermodynamics of shallow and deep semi-enclosed seas...provision of law , no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently...Navy Coastal Ocean Model (NCOM) code being developed in the ONR Ocean Model Development for COAMPS project. This model was first set up on the NPAC

  19. Chemical munitions dumped at sea

    Science.gov (United States)

    Edwards, Margo; Bełdowski, Jacek

    2016-06-01

    Modern chemical warfare is a byproduct of the industrial revolution, which created factories capable of rapidly producing artillery shells that could be filled with toxic chemicals such as chlorine, phosgene and mustard agent. The trench warfare of World War I inaugurated extensive deployments of modern chemical weapons in 1915. Concomitantly, the need arose to dispose of damaged, captured or excess chemical munitions and their constituents. Whereas today chemical warfare agents (CWA) are destroyed via chemical neutralization processes or high-temperature incineration in tandem with environmental monitoring, in the early to middle 20th century the options for CWA disposal were limited to open-air burning, burial and disposal at sea. The latter option was identified as the least likely of the three to impact mankind, and sea dumping of chemical munitions commenced. Eventually, the potential impacts of sea dumping human waste were recognized, and in 1972 an international treaty, the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, was developed to protect the marine environment from pollution caused by the dumping of wastes and other matter into the ocean. By the time this treaty, referred to as the London Convention, was signed by a majority of nations, millions of tons of munitions were known to have been disposed throughout the world's oceans.

  20. Fracture Networks in Sea Ice

    Directory of Open Access Journals (Sweden)

    Jonas Nesland Vevatne

    2014-04-01

    Full Text Available Fracturing and refreezing of sea ice in the Kara sea are investigated using complex networkanalysis. By going to the dual network, where the fractures are nodes and their intersectionslinks, we gain access to topological features which are easy to measure and hence comparewith modeled networks. Resulting network reveal statistical properties of the fracturing process.The dual networks have a broad degree distribution, with a scale-free tail, high clusteringand efficiency. The degree-degree correlation profile shows disassortative behavior, indicatingpreferential growth. This implies that long, dominating fractures appear earlier than shorterfractures, and that the short fractures which are created later tend to connect to the longfractures.The knowledge of the fracturing process is used to construct growing fracture network (GFNmodel which provides insight into the generation of fracture networks. The GFN model isprimarily based on the observation that fractures in sea ice are likely to end when hitting existingfractures. Based on an investigation of which fractures survive over time, a simple model forrefreezing is also added to the GFN model, and the model is analyzed and compared to the realnetworks.

  1. Distributions of dimethylsulfide in the Bohai Sea and Yellow Sea of China

    Institute of Scientific and Technical Information of China (English)

    HU Min; TANG Xiao-yan; LI Jin-long; MA Qi-ju

    2003-01-01

    Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during March 9-10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24-25, 1994 in Yellow Sea along the cruise from Shanghai to Qingdao. On the cruise in Bohai Sea DMS concentrations varied from 0. 11 to 2.63 nmol/L with an average of 1.31 nmol/L, while DMS flux Bohai Sea. DMS concentrations and fluxes had a similar spatial trend both in Bohai Sea and Yellow Sea with the correlation coefficients of 0.75 and 0.64, respectively.

  2. 南半球降水对南极海冰涛动异常的响应%RESPONSE OF SOUTHERN HEMISPHERE PRECIPITATION TO ANTARCTIC SEA ICE OSCILLATION ANOMALIES

    Institute of Scientific and Technical Information of China (English)

    窦挺峰; 效存德

    2013-01-01

    We analyzed the impact of Antarctic sea ice oscillation anomalies on Southern Hemisphere precipitation patterns using the global atmospheric general circulation model, NCAR/CAM3, and a climatic diagnosis method. We also conducted a preliminary investigation into the possible mechanism of action. Results showed that there was a significant response of precipitation to Antarctic sea ice oscillation anomalies, with a positive center over the Atlantic Ocean to the east of South America and a negative center over the Pacific Ocean to the west of South America. The spatial pattern was similar to the Antarctic sea ice oscillation. The results of numerical experiments indicated that sea ice oscillation anomalies can affect the middle troposphere by changing the surface heat flux which could drive the ascending branch of the Ferrel cell, strengthen or weaken the intensity of the Ferrel cell, and then influence the distribution of Southern Hemisphere precipitation. In the peripheral waters of the Amundsen-Bellingshausen Sea where sea ice concentration is lower than normal, upward heat flux could increase, making the ascending branch of the Ferrel cell abnormally strong. As a result, meridional transport would be enhanced and the descending branch strengthened, which would restrain the formation of precipitation in middle- and lower-latitude areas. In the peripheral waters of the Weddell Sea, where sea ice concentration is higher than normal, the responses of meridional transport and precipitation are almost the opposite. However, the response is much weaker at this longitude because of the land surface effect from the West Antarctic Peninsula and South America.%运用NCAR/CAM3全球大气环流模式,结合气候学诊断方法,分析了南极海冰涛动异常对南半球降水的影响,并对可能的作用机理进行了初步探讨.结果表明,南半球中纬度降水对海冰涛动异常的响应较为显著,且异常响应的空间分布与海冰涛动类似,分别

  3. Sea-level variation/change and thermal contribution in the Bering Sea

    Institute of Scientific and Technical Information of China (English)

    ZUO Juncheng; ZHANG Jianli; DU Ling; LI Peiliang; LI Lei

    2005-01-01

    The long-term sea-level trend in the Bering Sea is obtained by the analysis of TOPEX/Poseidon altimeter data, including the data of two tide gauges. The averaged sea-level in the Bering Sea rises at a rate of 2.47 mm/a from 1992 to 2002. The mean sea-level is falling in the most part of the Bering Sea, especially in its central basin, and it is rising in the northeastern part of the Bering Sea. During the 1998/99 change, the sea-level anomaly differences exhibit a significant sea-level anomaly fall in the deep basin of the Bering Sea,which is roughly in the same position where a prominent SST fall exists. The maximal fall of sea-level is about 10 cm in the southwestern part of the Bering Sea, and the maximal fall of about 2℃ in the SST also appeared in the same region as the sea level did.The steric sea-level change due to temperature variations is discussed. The results are compared with the TOPEX/Poseidon altimeter data at the different spatial scales. It is indicated that the seasonal amplitude of the steric height is about 35% of the observed TOPEX/Poseidon amplitude, which is much smaller than the 83% in the mid-latitudes area. The systematic difference between the TOPEX/Poseidon data with the range of about 7.5 cm and the thermal contribution with the range of about 2.5 cm is about 5 cm. This indicates that the thermal effect on the sea level is not as important as the case in the mid-latitudes area. In the Bering Sea, the phase of the steric height leads the observed sea level by about three months.

  4. The Suspended Sediment Concentration Distribution in the Bohai Sea, Yellow Sea and East China Sea

    Institute of Scientific and Technical Information of China (English)

    BIAN Changwei; JIANG Wensheng; Richard J.Greatbatch; DING Hui

    2013-01-01

    The distribution of the suspended sediment eoncentration (SSC) in the Bohai Sea,Yellow Sea and East China Sea (BYECS) is studied based on the observed turbidity data and model simulation results.The observed turbidity results show that (i)the highest SSC is found in the coastal areas while in the outer shelf sea areas turbid water is much more difficult to observe,(ii) the surface layer SSC is much lower than the bottom layer SSC and (iii) the winter SSC is higher than the summer SSC.The Regional Ocean Modeling System (ROMS) is used to simulate the SSC distribution in the BYECS.A comparison between the modeled SSC and the observed SSC in the BYECS shows that the modeled SSC can reproduce the principal features of the SSC distribution in the BYECS.The dynamic mechanisms of the sediment erosion and transport processes are studied based on the modeled results.The horizontal distribution of the SSC in the BYECS is mainly determined by the current-wave induced bottom stress and the fine-grain sediment distribution.The current-induced bottom stress is much higher than the wave-induced bottom stress,which means the tidal currents play a more significant role in the sediment resuspension than the wind waves.The vertical mixing strength is studied based on the mixed layer depth and the turbulent kinetic energy distribution in the BYECS.The strong winter time vertical mixing,which is mainly caused by the strong wind stress and surface cooling,leads to high surface layer SSC in winter.High surface layer SSC in summer is restricted in the coastal areas.

  5. Aerial Surveys of Endangered Whales in the Beaufort Sea, Chukchi Sea, and Northern Bering Sea.

    Science.gov (United States)

    1981-06-01

    16 Surveys of St Lawrence Island Nome to Point Barrow . . . 16 I Surveys of Barrow Area . . 18 Point Barrow to Deadhorse . . . 20 Surveys from...lease area, the Norton Basin - St . Lawrence Island area, the Hope Basin, and coastal portions of the Chukchi Sea. DESIGN The areas of study are listed...Bowhead Whale 314 857 Balaena mysticetus Beluga Whale** 284 3404 Delphinapterus leucas Gray Whale 2 6 Eschrichtius robustus Ring Seal 250 765 Phoca

  6. [Distribution and air-sea fluxes of methane in the Yellow Sea and the East China Sea in the spring].

    Science.gov (United States)

    Cao, Xing-Peng; Zhang, Gui-Ling; Ma, Xiao; Zhang, Guo-Ling; Liu, Su-Mei

    2013-07-01

    A survey was carried out in the Yellow Sea and the East China Sea from March 17 to April 06 of 2011. Dissolved CH4 in various depths were measured and sea-to-air fluxes were estimated. Methane concentrations in surface and bottom waters ranged between 2.39-29.67 nmol x L(-1) and 2.63-30.63 nmol x L(-1), respectively. Methane concentrations in bottom waters were slightly higher than those in surface waters, suggesting the existence of methane source in bottom waters or sediments. The horizontal distribution of dissolved CH4 showed a decrease from the river mouth to the open sea, and was influenced by the freshwater discharge and the Kuroshio intrusion. Surface methane saturations ranged from 93%-1 038%. Sea to air CH4 fluxes were (2.85 +/- 5.11) micromol x (m2 x d)(-1) (5.18 +/- 9.99) micromol x (m2 x d)(-1) respectively, calculated using the Liss and Merlivat (LM86), the Wanninkhof (W92) relationships and in situ wind speeds, and estimated emission rates of methane from the East China Sea and the Yellow Sea range from 7.05 x 10(-2) - 12.0 x 10(-2) Tg x a(-1) and 1.17 x 10(-2) - 2.20 x 10(-2) Tg x a(-1), respectively. The Yellow Sea and East China Sea are the net sources of atmospheric methane in the spring.

  7. Physics of the nucleon sea quark distributions

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R.

    2000-03-10

    Sea quark distributions in the nucleon have naively been expected to be generated perturbatively by gluon splitting. In this case, there is no reason for the light quark and anti-quark sea distributions to be different. No asymmetries in the strange or heavy quark sea distributions are predicted in the improved parton model. However,recent experiments have called these naive expectations into question. A violation of the Gottfried sum rule has been measured in several experiments, suggesting that (bar u) < (bar d) in the proton. Additionally, other measurements, while not definitive, show that there may be an asymmetry in the strange and anti-strange quark sea distributions. These effects may require nonperturbative explanations. In this review we first discuss the perturbative aspects of the sea quark distributions. We then describe the experiments that could point to nonperturbative contributions to the nucleon sea. Current phenomenological models that could explain some of these effects are reviewed.

  8. Sea ice, climate, and multiscale composites

    Science.gov (United States)

    Golden, Kenneth

    2014-03-01

    In September of 2012, the area of the Arctic Ocean covered by sea ice reached its lowest level ever recorded in more than three decades of satellite measurements. In fact, compared to the 1980's and 1990's, this represents a loss of more than half of the summer Arctic sea ice pack. While global climate models generally predict sea ice declines over the 21st century, the precipitous losses observed so far have significantly outpaced most projections. I will discuss how mathematical models of composite materials and statistical physics are being used to study key sea ice processes and advance how sea ice is represented in climate models. This work is helping to improve projections of the fate of Earth's ice packs, and the response of polar ecosystems. A brief video of a recent Antarctic expedition where sea ice properties were measured will be shown. Supported by NSF and ONR.

  9. Microplastic pollution in deep-sea sediments.

    Science.gov (United States)

    Van Cauwenberghe, Lisbeth; Vanreusel, Ann; Mees, Jan; Janssen, Colin R

    2013-11-01

    Microplastics are small plastic particles (microplastics have been accumulating in the marine environment for decades and have been detected throughout the water column and in sublittoral and beach sediments worldwide. However, up to now, it has never been established whether microplastic presence in sediments is limited to accumulation hot spots such as the continental shelf, or whether they are also present in deep-sea sediments. Here we show, for the first time ever, that microplastics have indeed reached the most remote of marine environments: the deep sea. We found plastic particles sized in the micrometre range in deep-sea sediments collected at four locations representing different deep-sea habitats ranging in depth from 1100 to 5000 m. Our results demonstrate that microplastic pollution has spread throughout the world's seas and oceans, into the remote and largely unknown deep sea.

  10. The Early Gulf of Mexico as a Subaerial Basin Below Sea Level (SABSEL) Basin. Evidence from Stratigraphy and Facies of Luanne salt, Norphlet sandstone and Smackover Brown Dense Formations.

    Science.gov (United States)

    Cassidy, M. M.

    2016-12-01

    Many workers recognize that large salt deposits form in post-rift sag basins which were subaerial and susceptible to rapid flooding from adjacent oceansl. I have termed these basins "subaerial basins below sea level" or "SABSEL" basins. A key marker of SABSEL basins are terrestrial sediments immediately overlain by deepwater sediments with no transition. Desert deposits -including Aeolian dunes- are preserved in the adiabatically heated depression. Dunes are not eroded by transgressing seas but are drowned by rising water as in a bath tub. They maintain their shape. Deepwater marine black shales or limestones drape the dunes. The Southern North sea is an example. Above the original marine shale over the dunes are evaporites. Winds descending into the basin were heated by adiabatic compression providing the very hot air need to allow survival of potassium salts. A similar situation was probably active during the Messinian salinity crisis in the Mediterranean basin, and the opening of the South Atlantic. In the Gulf of Mexico (GOM) a desert is on the Louann salt. Here the sea invaded the lows first to deposit the salt overlying tilted fault blocks of the opening basin, as in the Afar Triangle of Africa. In the GOM entry to the west fed in sea water, then closed. The Norphlet desert formed. Streams carried sands to the basin to be spread by winds where they willed, not limited to sand entry areas. Upon deposition their original weight depressed the salt. Seismic shows depressions in the salt but the dunes are high at the top Norphlet, forming distinctive small "eyes" at the top salt. The 600 foot dunes are draped by deep water dolomitic finely laminated organic rich black/ brown shale, the Brown Dense Facies of the Smackover formation. The lack of reworking of the dunes found by detailed seismic is distinctive of deposition in a SABSEL basin. The overlap of terrestrial sediments by deep water deposition is good evidence of sudden flooding. In summary this vertical

  11. Observed variability of sea surface salinity and thermal inversions in the Lakshadweep Sea during contrast monsoons

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishna, V.V.; Johnson, Z.; Salgaonkar, G.; Nisha, K.; Rajan, C.K.; Rao, R.R.

    The sea surface salinity (SSS) of the Lakshadweep Sea (LS) shows large seasonal variability due to horizontal advection of low (high) salinity waters from south (north) during winter (summer) monsoon. The measurements made in the LS during...

  12. Oceanographic cruise: Coral Sea, Arafura Sea, and Java Trench, April - May 1969 (NODC Accession 7100914)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This report contains oceanographic data which was obtained aboard HMAS DIAMANTINA during an oceanographic cruise in the Coral Sea, Arafura Sea, and Java Trench...

  13. First biological measurements of deep-sea corals from the Red Sea.

    KAUST Repository

    Roder, Cornelia

    2013-10-03

    It is usually assumed that metabolic constraints restrict deep-sea corals to cold-water habitats, with \\'deep-sea\\' and \\'cold-water\\' corals often used as synonymous. Here we report on the first measurements of biological characters of deep-sea corals from the central Red Sea, where they occur at temperatures exceeding 20°C in highly oligotrophic and oxygen-limited waters. Low respiration rates, low calcification rates, and minimized tissue cover indicate that a reduced metabolism is one of the key adaptations to prevailing environmental conditions. We investigated four sites and encountered six species of which at least two appear to be undescribed. One species is previously reported from the Red Sea but occurs in deep cold waters outside the Red Sea raising interesting questions about presumed environmental constraints for other deep-sea corals. Our findings suggest that the present understanding of deep-sea coral persistence and resilience needs to be revisited.

  14. Retrieval of chlorphyll from the sea-leaving radiance in the Arbaian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sathe, P.V.; Jadhav, N.

    Error estimates in chlorophyll retrieval in the sea from satellite data have always been higher compared to the errors in retrieval of sea surface temperature or wind speed from satellite data. This is due to the higher percentage of noise...

  15. GHRSST Level 4 ODYSSEA Mediterranean Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at Ifremer/CERSAT...

  16. First biological measurements of deep-sea corals from the Red Sea.

    Science.gov (United States)

    Roder, C; Berumen, M L; Bouwmeester, J; Papathanassiou, E; Al-Suwailem, A; Voolstra, C R

    2013-10-03

    It is usually assumed that metabolic constraints restrict deep-sea corals to cold-water habitats, with 'deep-sea' and 'cold-water' corals often used as synonymous. Here we report on the first measurements of biological characters of deep-sea corals from the central Red Sea, where they occur at temperatures exceeding 20°C in highly oligotrophic and oxygen-limited waters. Low respiration rates, low calcification rates, and minimized tissue cover indicate that a reduced metabolism is one of the key adaptations to prevailing environmental conditions. We investigated four sites and encountered six species of which at least two appear to be undescribed. One species is previously reported from the Red Sea but occurs in deep cold waters outside the Red Sea raising interesting questions about presumed environmental constraints for other deep-sea corals. Our findings suggest that the present understanding of deep-sea coral persistence and resilience needs to be revisited.

  17. The lowering of sea surface temperature in the east central Arabian sea associated with a cyclone

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Rao, D.P.; Sastry, J.S.

    An analysis of thermal Structure in the East Central Arabian Sea associated with a moderate cyclone is presented. The heat storage and the heat budget components have been computed. Under the influence of the cyclone the Sea Surface Temperature (SST...

  18. GHRSST Level 4 EUR Mediterranean Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily by Ifremer/CERSAT (France) using optimal...

  19. Impact of sea ice initialization on sea ice and atmosphere prediction skill on seasonal timescales

    Science.gov (United States)

    Guemas, V.; Chevallier, M.; Déqué, M.; Bellprat, O.; Doblas-Reyes, F.

    2016-04-01

    We present a robust assessment of the impact of sea ice initialization from reconstructions of the real state on the sea ice and atmosphere prediction skill. We ran two ensemble seasonal prediction experiments from 1979 to 2012 : one using realistic sea ice initial conditions and another where sea ice is initialized from a climatology, with two forecast systems. During the melting season in the Arctic Ocean, sea ice forecasts become skilful with sea ice initialization until 3-5 months ahead, thanks to the memory held by sea ice thickness. During the freezing season in both the Arctic and Antarctic Oceans, sea ice forecasts are skilful for 7 and 2 months, respectively, with negligible differences between the two experiments, the memory being held by the ocean heat content. A weak impact on the atmosphere prediction skill is obtained.

  20. Sea otter health: challenging a pet hypothesis

    Science.gov (United States)

    Lafferty, Kevin D.

    2015-01-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission.

  1. Sea Surface Salinity : Research Challenges and Opportunities

    Science.gov (United States)

    Halpern, David; Lagerloef, Gary; Font, Jordi

    2012-01-01

    Sea surface salinity (SSS) can be important in regulating sea surface temperature (SST). Two technological breakthrough satellite SSS missions, Aquarius and Soil Moisture and Ocean Salinity (SMOS), are currently producing high-quality SSS data. This paper provides an overview of the importance of SSS for weather and climate applications and describes the Aquarius and SMOS missions. The newness of adequately sampled SSS data prompted a first-time at-sea field campaign devoted to improved understanding of SSS variations.

  2. Navigation Issues in the South China Sea

    OpenAIRE

    2005-01-01

    The South China Sea is one of the most important sea lanes with numerous competing sovereignty disputes. The freedom of navigation in this region is critical to all major trading States in the world. After an introduction to the navigational regimes of UNCLOS, this article describes the whole navigation situation in this region, by separately introducing the navigation issues in the territorial sea, straits, archipelagic waters and the Spratly area. Meanwhile, since the legal status of the ma...

  3. Physical oceanography of the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Leppaeranta, Matti [Helsinki Univ. (Finland). Dept. of Physics; Myrberg, Kai [Finnish Institute of Marine Research, Helsinki (Finland)

    2009-07-01

    The Baltic Sea oceanographic research community is wide and the research history is over 100 years old. Nevertheless, there is still no single, coherent book on the physical oceanography of the Baltic Sea as a whole. There is a strong need for such a book, coming from working oceanographers as well as the university teaching programmes in advanced undergraduate to graduate levels. In the regional conference series in physical oceanography (Baltic Sea Science Conference, Baltic Sea Oceanographers' conference, Baltex-conferences) about 500 scientists take part regularly. Even more scientists work in the fields of marine biology, chemistry and the environment, and they need information on the physics of the Baltic Sea as well. There are nine countries bordering on the Baltic Sea and five more in the runoff area. The Baltic Sea as a source of fish, means of transportation and leisure activities is highly important to the regional society. In the runoff area there are a total of 85 million people. Research and protection strategies need to be developed, as the Baltic Sea is probably the most polluted sea in the world. Since the Baltic Sea has become an inner sea of the EU (apart from small shore parts of Russia in Petersburg and Kaliningrad), it is anticipated that the importance of the region will consequently rise. The book will arouse interest among students, scientists and decision makers involved with the Baltic problems. It will also give important background information for those working with biogeochemical processes in the Baltic Sea, because the physical forcing for those processes is of vital importance. (orig.)

  4. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Artic Sea Ice Cover

    Science.gov (United States)

    2015-11-30

    Arctic sea ice cover and its impact on the heat and mass balance of the ice and upper ocean ... Arctic Ocean and surrounding seas, with particular emphasis on the Chukchi and Beaufort Seas. Some of the largest changes to the sea ice cover are...other parts of the Arctic ice cover appear to now be accelerating. Figure 6. Maps of the linear trend of annual solar heat input to the ocean

  5. Comparison among four kinds of data of sea surface wind stress in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    谢强; 王卫强; 毛庆文

    2002-01-01

    By using remote sensing (ERS) data, FSU data, GOADS data and Hellerman & Rcsenstein objective analysis data to analyze the sea surface wind stress in the South China Sea, it is found that the remote sensing data have higher resolution and more reasonable values. Therefore we suggest that remote sensing data be chosen in the study of climatological features of sea surface wind stress and its seasonal variability in the South China Sea, especially in the study of small and middle scale eddies.

  6. Arctic tides from GPS on sea ice

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing...... of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic. The GPS measurements are compared with the Arctic tidal model AOTIM-5, which assimilates tide...

  7. Dynamic Singularity Spectrum Distribution of Sea Clutter

    Science.gov (United States)

    Xiong, Gang; Yu, Wenxian; Zhang, Shuning

    2015-12-01

    The fractal and multifractal theory have provided new approaches for radar signal processing and target-detecting under the background of ocean. However, the related research mainly focuses on fractal dimension or multifractal spectrum (MFS) of sea clutter. In this paper, a new dynamic singularity analysis method of sea clutter using MFS distribution is developed, based on moving detrending analysis (DMA-MFSD). Theoretically, we introduce the time information by using cyclic auto-correlation of sea clutter. For transient correlation series, the instantaneous singularity spectrum based on multifractal detrending moving analysis (MF-DMA) algorithm is calculated, and the dynamic singularity spectrum distribution of sea clutter is acquired. In addition, we analyze the time-varying singularity exponent ranges and maximum position function in DMA-MFSD of sea clutter. For the real sea clutter data, we analyze the dynamic singularity spectrum distribution of real sea clutter in level III sea state, and conclude that the radar sea clutter has the non-stationary and time-varying scale characteristic and represents the time-varying singularity spectrum distribution based on the proposed DMA-MFSD method. The DMA-MFSD will also provide reference for nonlinear dynamics and multifractal signal processing.

  8. Quantification of ikaite in Antarctic sea ice

    Directory of Open Access Journals (Sweden)

    M. Fischer

    2012-02-01

    Full Text Available Calcium carbonate precipitation in sea ice can increase pCO2 during precipitation in winter and decrease pCO2 during dissolution in spring. CaCO3 precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice. This is the first quantitative study of hydrous calcium carbonate, as ikaite, in sea ice and discusses its potential significance for the carbon cycle in polar oceans. Ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during an expedition in the East Antarctic and another off Terre Adélie, Antarctica. Samples were analysed for CaCO3, Salinity, DOC, DON, Phosphate, and total alkalinity. A relationship between the measured parameters and CaCO3 precipitation could not be observed. We found calcium carbonate, as ikaite, mostly in the top layer of sea ice with values up to 126 mg ikaite per liter melted sea ice. This potentially represents a contribution between 0.12 and 9 Tg C to the annual carbon flux in polar oceans. The horizontal distribution of ikaite in sea ice was heterogenous. We also found the precipitate in the snow on top of the sea ice.

  9. Physicochemical Studies of the Sea Surface Microlayer.

    Science.gov (United States)

    Zhengbin; Liansheng; Zhijian; Jun; Haibing

    1998-08-15

    The sea surface microlayer and its thickness are theoretically analyzed. A multiple-layer model of the sea surface microlayer is proposed. Through in situ and laboratory imitation experiments using glass plate, rotating drum, screen, and funnel samplers, the relationships between pH, surface tension, the concentrations of dissolved trace metals Cu and Pb, phosphate, and particulate and sampling thicknesses are carefully investigated. The apparent sampling thickness of the sea surface microlayer is determined to be 50 +/- 10 µm, which is basically consistent with the mean thickness of the liquid boundary film in the models of gas exchange across the sea surface. Copyright 1998 Academic Press.

  10. Parasites in the Wadden Sea food web

    Science.gov (United States)

    Thieltges, David W.; Engelsma, Marc Y.; Wendling, Carolin C.; Wegner, K. Mathias

    2013-09-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest a multitude of effects on the hosts. This also includes effects on specific predator-prey relationships and the general structure of the food web. Focussing on molluscs, a major group in the Wadden Sea in terms of biomass and abundance and an important link between primary producers and predators, we review existing studies and exemplify the ecological role of parasites in the Wadden Sea food web. First, we give a brief inventory of parasites occurring in the Wadden Sea, ranging from microparasites (e.g. protozoa, bacteria) to macroparasites (e.g. helminths, parasitic copepods) and discuss the effects of spatial scale on heterogeneities in infection levels. We then demonstrate how parasites can affect host population dynamics by acting as a strong mortality factor, causing mollusc mass mortalities. In addition, we will exemplify how parasites can mediate the interaction strength of predator-prey relationships and affect the topological structure of the Wadden Sea food web as a whole. Finally, we highlight some ongoing changes regarding parasitism in the Wadden Sea in the course of global change (e.g. species introduction, climate change) and identify important future research questions to entangle the role of parasites in the Wadden Sea food web.

  11. On sea level - ice sheet interactions

    Science.gov (United States)

    Gomez, Natalya Alissa

    This thesis focuses on the physics of static sea-level changes following variations in the distribution of grounded ice and the influence of these changes on the stability and dynamics of marine ice sheets. Gravitational, deformational and rotational effects associated with changes in grounded ice mass lead to markedly non-uniform spatial patterns of sea-level change. I outline a revised theory for computing post-glacial sea-level predictions and discuss the dominant physical effects that contribute to the patterns of sea-level change associated with surface loading on different timescales. I show, in particular, that a large sea-level fall (rise) occurs in the vicinity of a retreating (advancing) ice sheet on both short and long timescales. I also present an application of the sea-level theory in which I predict the sea-level changes associated with a new model of North American ice sheet evolution and consider the implications of the results for efforts to establish the sources of Meltwater Pulse 1A. These results demonstrate that viscous deformational effects can influence the amplitude of sea-level changes observed at far-field sea-level sites, even when the time window being considered is relatively short (≤ 500 years). Subsequently, I investigate the feedback of sea-level changes on marine ice-sheet stability and dynamics by coupling a global sea-level model to ice-sheet models of increasing complexity. To begin, I incorporate gravitationally self-consistent sea-level changes into an equilibrium marine ice-sheet stability theory to show that the sea-level changes have a stabilizing influence on ice-sheet retreat. Next, I consider the impact of the stabilizing mechanism on the timescale of ice-sheet retreat using a 1D dynamic coupled ice sheet - sea level model. Simulations with the coupled model, which incorporate viscoelastic deformation of the solid Earth, show that local sea-level changes at the grounding line act to slow, and in some cases, halt

  12. Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

    Directory of Open Access Journals (Sweden)

    R. A. Ibrayev

    2010-03-01

    Full Text Available A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. The model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

  13. Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

    Directory of Open Access Journals (Sweden)

    R. A. Ibrayev

    2009-09-01

    Full Text Available A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. Model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

  14. Sea Turtle Conservation on Bonaire. Sea Turtle Club Bonaire 1997. Project Report

    NARCIS (Netherlands)

    Schuit, M.; Put, van A.L.L.M.; Valkering, N.P.; Eijck, van T.J.W.

    1998-01-01

    The Sea Turtle Club Bonaire (STCB) is a non-governmental, non-profit organization. Its main goal is the conservation of the sea turtles that occur on Bonaire. To reach this goal, annual projects are undertaken, such as research and the promotion of public awareness on sea turtle conservation. The ST

  15. Long Term Sea Level Change and Water Mass Balance in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    RONG Zengrui; LIU Yuguang; ZONG Haibo; XIU Peng

    2009-01-01

    Sea level anomalies observed by altimeter during the 1993-2006 period, thermosterie sea level anomalies estimated by using subsurface temperature data produced by Ishii and SODA reanalysis data, tide gauge records and HOAPS freshwater flux data were analyzed to investigate the long term sea level change and the water mass balance in the South China Sea. The altimeter-observed sea level showed a rising rate of (3.5±0.9)mm yr-1 during the period 1993-2006, but this figure was considered to have been highly distorted by the relatively short time interval and the large inter-decadal variability, which apparently exists in both the thermosteric sea level and the observed sea level. Long term thermosteric sea level from 1945 to 2004 gave a rising rate of 0.15±0.06 mmyr-1. Tide gauge data revealed this discrepancy and the regional distributions of the sea-level trends. Both the 'real' and the thermosteric sea level showed a good correspondence to ENSO: decreasing during E1 Nifio years and increasing during La Nina years. Amplitude and phase differences between the 'real' sea level and the thermosteic sea level were substantially revealed on both seasonal and interannual time scales. As one of the possible factors, the freshwater flux might play an important role in balancing the water mass.

  16. Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial

    NARCIS (Netherlands)

    Trommer, G.; Siccha, M.; Rohling, E.J.; Grant, K.; van der Meer, M.T.J.; Schouten, S.; Baranowski, U.; Kucera, M.

    2011-01-01

    This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by

  17. Authigenic gypsum in a deep sea core from Southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.

    Authigenic gypsum has been encountered in a deep sea core RC9-157 from the southeastern Arabian Sea at a depth of 4111 m which is a zone of lysocline. The formation of gypsum in the deep sea region is attributed to the prevailing sulphate rich...

  18. Sea Turtle Conservation on Bonaire. Sea Turtle Club Bonaire 1997. Project Report

    NARCIS (Netherlands)

    Schuit, M.; Put, van A.L.L.M.; Valkering, N.P.; Eijck, van T.J.W.

    1998-01-01

    The Sea Turtle Club Bonaire (STCB) is a non-governmental, non-profit organization. Its main goal is the conservation of the sea turtles that occur on Bonaire. To reach this goal, annual projects are undertaken, such as research and the promotion of public awareness on sea turtle conservation. The

  19. Morphotype patterns of Norwegian Sea deep-sea benthic foraminifera and ecological implications

    Science.gov (United States)

    Corliss, Bruce H.; Chen, Christina

    1988-08-01

    Deep-sea benthic foraminifera from Norwegian Sea surface sediments are classified into morphotypes on the basis of test shape and nature of test coiling and show distinct patterns with water depth. The morphotype data are used to determine microhabitat patterns of the foraminifera, which are suggested to be related to the organic-carbon content of the surficial deep-sea sediments.

  20. Long-term sea level change in the Malaysian seas from multi-mission altimetry data

    NARCIS (Netherlands)

    Din, A.H.; Omar, K.M.; Naeije, M.C.; Ses, S.

    2012-01-01

    The long-term sea level change during 1993 to 2008 was investigated in the Malaysian seas from satellite altimetry data of the TOPEX, JASON-1, ERS-1, ERS-2 and ENVISAT missions. Sea level data retrieval and reduction were carried out using the radar altimeter database system (RADS). In RADS data pro

  1. Sea Turtle Conservation on Bonaire. Sea Turtle Club Bonaire 1997. Project Report

    NARCIS (Netherlands)

    Schuit, M.; Put, van A.L.L.M.; Valkering, N.P.; Eijck, van T.J.W.

    1998-01-01

    The Sea Turtle Club Bonaire (STCB) is a non-governmental, non-profit organization. Its main goal is the conservation of the sea turtles that occur on Bonaire. To reach this goal, annual projects are undertaken, such as research and the promotion of public awareness on sea turtle conservation. The ST

  2. Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino

    Science.gov (United States)

    Sallenger, A.H.; Krabill, W.; Brock, J.; Swift, R.; Manizade, S.; Stockdon, H.

    2002-01-01

    Over time scales of hundreds to thousands of years, the net longshore sand transport direction along the central California coast has been driven to the south by North Pacific winter swell. In contrast, during the El Nin??o winter of 1997-1998, comparisons of before and after airborne lidar surveys showed sand was transported from south to north and accumulated on the south sides of resistant headlands bordering pocket beaches. This resulted in significant beach erosion at the south ends of pocket beaches and deposition in the north ends. Coincident with the south-to-north redistribution of sand, shoreline morphology became prominently cuspate with longshore wavelengths of 400-700 m. The width and elevation of beaches were least where maximum shoreline erosion occurred, preferentially exposing cliffs to wave attack. The resulting erosional hotspots typically were located in the embayments of giant cusps in the southern end of the pocket beaches. The observed magnitude of sea cliff retreat, which reached 14 m, varied with the number of hours that extreme wave runup exceeded certain thresholds representing the protective capacity of the beach during the El Nin??o winter. A threshold representing the width of the beach performed better than a threshold representing the elevation of the beach. The magnitude of cliff erosion can be scaled using a simple model based on the cross-shore distance that extreme wave runup exceeded the pre-winter cliff position. Cliff erosion appears to be a balance between terrestrial mass wasting processes, which tend to decrease the cliff slope, and wave attack, which removes debris and erodes the cliff base increasing the cliff slope. ?? 2002 Elsevier Science B.V. All rights reserved.

  3. Ordenisaajate seas seisab arvukalt riigiteenistujaid

    Index Scriptorium Estoniae

    2004-01-01

    Riikliku autasu saajate nimekiri. Teenetemärgi saajate seas muusikud: Valgetähe III klass Henn Tiivel. Valgetähe IV klass Johannes Jürisson, Valeri Petrov, Aadu Regi, Helga Surva, Kalle Tamra. Valgetähe V klass Kalev Kuljus, Jaan Mikkel, Heidi Mägi, Heino Mähar, Sigrid Orusaar, Aarne Saluveer, Heli Lääts, Ludmilla Toon. Valgetähe medal Endla Jaanus, Ralf Kaup, Aadu Kukk, Tiit Köster, Heino Pehk, Tiiu Schüts

  4. Filling regulatory gaps in high seas fisheries: discrete high seas fish stocks, deep-sea fisheries and vulnerable marine ecosystems

    NARCIS (Netherlands)

    Takei, Y.

    2008-01-01

    The present study examines the legal regime of high seas fisheries with a view to identifying regulatory gaps. The main research questions are as follows: 1. What general principles are applicable to high seas fisheries?; 2. What implications do these general principles have for new challenges in th

  5. Deep-sea pollen research in China

    Institute of Scientific and Technical Information of China (English)

    SUN Xiangjun; LUO Yunli; CHEN Huaicheng

    2003-01-01

    This paper briefly presents the progress of deep-sea pollen research in China since the beginning ofninetieths of the last Century. All the deep-sea pollen contri-butions mainly come from the South China Sea (SCS) andthe East China Sea (ECS). The German-Chinese joint cruise(Sonne 95) and ODP 184 cruise initiated by Chinese scientistsin the SCS provided excellent material for the deep-sea pol-len research. So far a number of pollen results of 20-30 kaand million years from the SCS have been published. A couple of deep-sea pollen records from Okinawa Through of the ECS also came out. The high resolution pollen records obtained from the continuous deposits with high sedimentation rates and reliable age control of the deep-sea sediments provided a high time resolution history (hundred to millennial scales) of vegetation, environment and monsoon evolution of the pollen source areas (southern China and Japan). Spectral analysis of deep-sea pollen records from the SCS discovered orbital (100, 41, 23, 10 ka) and suborbital cyclicities (Heinrich and Dansgaard/Oscheger-O/D events) in the vege-tation changes. Moreover, cross spectral analysis showed that the trend of vegetation changes in northern SCS was regulated mainly by changes of the ice volume in the Northern Hemisphere. The pollen record of the last 20 ka from the Okinawa Through of the ECS indicates that the marine environmental change lagged that on the terrestrail by about 1000 year. The asynchronous environmental changes between land and sea were probably caused by the time difference in thermohaline circulation. This study underscored the role of the deep-sea plant fossils as a bridge across the land and sea.

  6. Biogeochemical Coupling between Ocean and Sea Ice

    Science.gov (United States)

    Wang, S.; Jeffery, N.; Maltrud, M. E.; Elliott, S.; Wolfe, J.

    2016-12-01

    Biogeochemical processes in ocean and sea ice are tightly coupled at high latitudes. Ongoing changes in Arctic and Antarctic sea ice domain likely influence the coupled system, not only through physical fields but also biogeochemical properties. Investigating the system and its changes requires representation of ocean and sea ice biogeochemical cycles, as well as their coupling in Earth System Models. Our work is based on ACME-HiLAT, a new offshoot of the Community Earth System Model (CESM), including a comprehensive representation of marine ecosystems in the form of the Biogeochemical Elemental Cycling Module (BEC). A full vertical column sea ice biogeochemical module has recently been incorporated into the sea ice component. We have further introduced code modifications to couple key growth-limiting nutrients (N, Si, Fe), dissolved and particulate organic matter, and phytoplankton classes that are important in polar regions between ocean and sea ice. The coupling of ocean and sea ice biology-chemistry will enable representation of key processes such as the release of important climate active constituents or seeding algae from melting sea ice into surface waters. Sensitivity tests suggest sea ice and ocean biogeochemical coupling influences phytoplankton competition, biological production, and the CO2 flux. Sea ice algal seeding plays an important role in determining phytoplankton composition of Arctic early spring blooms, since different groups show various responses to the seeding biomass. Iron coupling leads to increased phytoplankton biomass in the Southern Ocean, which also affects carbon uptake via the biological pump. The coupling of macronutrients and organic matter may have weaker influences on the marine ecosystem. Our developments will allow climate scientists to investigate the fully coupled responses of the sea ice-ocean BGC system to physical changes in polar climate.

  7. A Heavy Sea Fog Event over the Yellow Sea in March 2005:Analysis and Numerical Modeling

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, a heavy sea fog episode that occurred over the Yellow Sea on 9 March 2005 is investigated.The sea fog patch, with a spatial scale of several hundred kilometers at its mature stage, reduced visibility along the Shandong Peninsula coast to 100 m or much less at some sites. Satellite images, surface observations and soundings at islands and coasts, and analyses from the Japan Meteorology Agency (JMA) are used to describe and analyze this event. The analysis indicates that this sea fog can be categorized as advection cooling fog. The main features of this sea fog including fog area and its movement are reasonably reproduced by the Fifth-generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5). Model results suggest that the formation and evolution of this event can be outlined as:(1) southerly warm/moist advection of low-level air resulted in a strong sea-surface-based inversion with a thickness of about 600 m; (2) when the inversion moved from the warmer East Sea to the colder Yellow Sea, a thermal internal boundary layer (TIBL) gradually formed at the base of the inversion while the sea fog grew in response to cooling and moistening by turbulence mixing; (3) the sea fog developed as the TIBL moved northward and (4) strong northerly cold and dry wind destroyed the TIBL and dissipated the sea fog. The principal findings of this study are that sea fog forms in response to relatively persistent southerly warm/moist wind and a cold sea surface, and that turbulence mixing by wind shear is the primary mechanism for the cooling and moistening the marine layer. In addition, the study of sensitivity experiments indicates that deterministic numerical modeling offers a promising approach to the prediction of sea fog over the Yellow Sea but it may be more efficient to consider ensemble numerical modeling because of the extreme sensitivity to model input.

  8. Air-sea CO2 fluxes on the Bering Sea shelf

    Directory of Open Access Journals (Sweden)

    M. A. Jeffries

    2011-05-01

    Full Text Available There have been few previous studies of surface seawater CO2 partial pressure (pCO2 variability and air-sea CO2 gas exchange rates for the Bering Sea shelf. In 2008, spring and summertime observations were collected in the Bering Sea shelf as part of the Bering Sea Ecological Study (BEST. Our results indicate that the Bering Sea shelf was close to neutral in terms of CO2 sink-source status in springtime due to relatively small air-sea CO2 gradients (i.e., ΔpCO2 and sea-ice cover. However, by summertime, very low seawater pCO2 values were observed and much of the Bering Sea shelf became strongly undersaturated with respect to atmospheric CO2 concentrations. Thus the Bering Sea shelf transitions seasonally from mostly neutral conditions to a strong oceanic sink for atmospheric CO2 particularly in the "green belt" region of the Bering Sea where there are high rates of phytoplankton primary production (PPand net community production (NCP. Ocean biological processes dominate the seasonal drawdown of seawater pCO2 for large areas of the Bering Sea shelf, with the effect partly countered by seasonal warming. In small areas of the Bering Sea shelf south of the Pribilof Islands and in the SE Bering Sea, seasonal warming is the dominant influence on seawater pCO2, shifting localized areas of the shelf from minor/neutral CO2 sink status to neutral/minor CO2 source status, in contrast to much of the Bering Sea shelf. Overall, we compute that the Bering Sea shelf CO2 sink in 2008 was 157 ± 35 Tg C yr−1 (Tg = 1012 g C and thus a strong sink for CO2.

  9. Variability of surface meteorological parameters over the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Fernandes, A.A.

    The trends and periodicities of surface meteorological parameters (sea surface temperature, air temperature, cloudiness, wind speed and sea level pressure) over the western, central, eastern and southern Arabian Sea regions are studied...

  10. Multisensor Analyzed Sea Ice Extent - Northern Hemisphere (MASIE-NH)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Multisensor Analyzed Sea Ice Extent Northern Hemisphere (MASIE-NH) products provide measurements of daily sea ice extent and sea ice edge boundary for the...

  11. Mapping of sea bottom topography

    Science.gov (United States)

    Calkoen, C. J.; Wensink, G. J.; Hesselmans, G. H. F. M.

    1992-01-01

    Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected.

  12. BACTERIAL DESEASES IN SEA FISH

    Directory of Open Access Journals (Sweden)

    Ivančica Strunjak-Perović

    1997-10-01

    Full Text Available With development of the fish culturing in the sea, the interest in their health also increased. The reason for this are diseases or rather mortality that occur in such controlled cultures and cause great economic losses. By growing large quantities of fish in rather small species, natural conditions are changed, so fish is more sensitive and prone to infection agents (viruses, bacteria, parasites. Besides, a large fish density in the cultural process accelerates spreading if the diseases, but also enables a better perception of them. In wild populations sick specimen very quickly become predator’s prey, witch makes it difficult to note any pathological changes in such fish. There are lots of articles on viral, bacterial and parasitic diseases nowdays, but this work deals exclusively with bacterial deseases that occur in the controlled sea cultures (vibriosis, furunculosis, pastherelosis, nocardiosis, mycobaceriosis, edwardsielosis, yersiniosis, deseases caused by bacteria of genera Flexibacter, Pseudomonas, Aeromonas, Streptococus and bacteria nephryithis. Yet, the knowledge of these deseases vary, depending on wether a fish species is being cultured for a longer period of time or is only being introduced in the controlled culture.

  13. CO2 and sea level

    Science.gov (United States)

    Bell, Peter M.

    There is considerable discussion currently about the potential effects of carbon dioxide build-up in the atmosphere over the next several decades. The sources of information are two Government funded reports, one by the National Research Council (NRC), the other by the Environment Protection Agency (EPA), both were released within the last five months. The reports were described recently as being conservative, although the consequences of the resulting greenhouse effects are deemed inevitable. Atmospheric warming on a global scale of as much as 5°C cannot be avoided, only perhaps delayed by a few years at best (Environ. Sci. Technol, 18, 45A-46A, 1984). The cause is the burning of fossil fuels. Oil will not be too important because its supplies are predictably exhausted on the time scale of 50-100 years. Coal burning is considered as the main source of carbon dioxide. Among the more spectacular results of a global temperature rise over the next 100 years is the expected rise in sea level of a minimum of 70 cm (Oceanus, Winter, 1983/84). If the West Antarctic Ice Sheet breaks up and melts, the rise could be in the several meter range. Sea level rose only 15 cm in the past century.

  14. Snow on Antarctic sea ice

    Science.gov (United States)

    Massom, Robert A.; Eicken, Hajo; Hass, Christian; Jeffries, Martin O.; Drinkwater, Mark R.; Sturm, Matthew; Worby, Anthony P.; Wu, Xingren; Lytle, Victoria I.; Ushio, Shuki; Morris, Kim; Reid, Phillip A.; Warren, Stephen G.; Allison, Ian

    2001-08-01

    Snow on Antarctic sea ice plays a complex and highly variable role in air-sea-ice interaction processes and the Earth's climate system. Using data collected mostly during the past 10 years, this paper reviews the following topics: snow thickness and snow type and their geographical and seasonal variations; snow grain size, density, and salinity; frequency of occurrence of slush; thermal conductivity, snow surface temperature, and temperature gradients within snow; and the effect of snow thickness on albedo. Major findings include large regional and seasonal differences in snow properties and thicknesses; the consequences of thicker snow and thinner ice in the Antarctic relative to the Arctic (e.g., the importance of flooding and snow-ice formation); the potential impact of increasing snowfall resulting from global climate change; lower observed values of snow thermal conductivity than those typically used in models; periodic large-scale melt in winter; and the contrast in summer melt processes between the Arctic and the Antarctic. Both climate modeling and remote sensing would benefit by taking account of the differences between the two polar regions.

  15. MIDDLE-LATE JURASSIC HIGH-RESOLUTION SUBSIDENCE ANALYSIS AND ITS IMPLICATION OF THE BERYL EMBAYMENT, VIKING GRABEN, NORTH SEA%北海维京地堑Beryl湾中、晚侏罗世高分辨率沉降分析及其意义

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    在Beryl湾发育南北向、北西向和北东向三组正断层.根据北海维京地堑Beryl湾73口井的高分辨率层序地层学分析和高分辨率沉降分析,阐明中、晚侏罗世沉积和沉降模式,确定应力场的变化及边界断层的连锁对沉积和含油气系统的控制作用.高分辨率(1~2Ma)允许评价不同走向断层随时间的演化.不仅阐明了东舍德兰断层连锁的时间和机制,而且阐明了对沉积相的控制作用.研究结果表明,在中、晚侏罗世同裂谷期Beryl湾伸展方向发生了45°的顺时针旋转;东舍德兰断层在早、中牛津期由两段连锁为一条统一的断层.

  16. Interpretation and Implications of Previous Sea Pay Estimates

    Science.gov (United States)

    2015-04-01

    amount of sea duty that can be gained from a rise in Career Sea Pay and Career Sea Pay Premium . The second was how to separate multiple effects of sea...linear pricing scheme that would induce personnel to reveal important information about their willingness to reenlist and their willingness to...undertake sea duty. Under this pricing mechanism, the Navy could fashion combinations of Selective Reenlistment Bonuses and sea pays that would achieve

  17. The application of ERTS imagery to monitoring Arctic sea ice. [mapping ice in Bering Sea, Beaufort Sea, Canadian Archipelago, and Greenland Sea

    Science.gov (United States)

    Barnes, J. C. (Principal Investigator); Bowley, C. J.

    1974-01-01

    The author has identified the following significant results. Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS-1 imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft. The results of the investigation demonstrate that ERTS-1 imagery has substantial practical application for monitoring arctic sea ice. Ice features as small as 80-100 m in width can be detected, and the combined use of the visible and near-IR imagery is a powerful tool for identifying ice types. Sequential ERTS-1 observations at high latitudes enable ice deformations and movements to be mapped. Ice conditions in the Bering Sea during early March depicted in ERTS-1 images are in close agreement with aerial ice observations and photographs.

  18. Teaching Wide Sargasso Sea in New Jersey

    Science.gov (United States)

    Jolley, Susan Arpajian

    2005-01-01

    High school teacher Susan Arpajian Jolley emphasizes experience and understanding by using the related novels "Wide Sargasso Sea" and "Jane Eyre" to help her students travel into unfamiliar cultural territory. "Wide Sargasso Sea" relates to Caribbean history and culture, feminism, race relations, colonialism, and personal identity.

  19. Teaching Wide Sargasso Sea in New Jersey

    Science.gov (United States)

    Jolley, Susan Arpajian

    2005-01-01

    High school teacher Susan Arpajian Jolley emphasizes experience and understanding by using the related novels "Wide Sargasso Sea" and "Jane Eyre" to help her students travel into unfamiliar cultural territory. "Wide Sargasso Sea" relates to Caribbean history and culture, feminism, race relations, colonialism, and…

  20. Seasonal variability in the Baltic Sea level

    Directory of Open Access Journals (Sweden)

    Marek Świrgoń

    2013-11-01

    Full Text Available Sea level is subject to spatial and temporal variability on different scales. In this paper we investigate seasonal variability in the open Baltic Sea level using daily satellite altimetry data for the period 1 January 1993-31 December 2010. Our results indicate that there is a well-pronounced seasonal cycle in the 18-year average sea level and in its standard deviation. The average annual SLA amplitude in the open Baltic Sea is about 18 cm. The seasonal cycle of the SLA in the Baltic Sea is asymmetric in shape. In the autumn and winter (about 240-260 days per year, the 18-year average daily SLA are higher than the 18-year annual average SLA. In the spring and summer (about 100-120 days per year, the 18-year average daily SLA are lower than the 18-year annual average SLA. A similar asymmetry of the seasonal cycle is not observed in the North Sea and North Atlantic SLA data. The annual pattern of the sea level variability in the Baltic Sea is evident if one considers multi-year average time series, but the cycle can be obscured in some years.