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Sample records for beaufort sea

  1. Beaufort Sea: information update

    SciTech Connect

    Becker, P.R.

    1988-04-01

    The report is based on a multi-disciplinary meeting held March 6-7, 1985, as part of preparations for the Beaufort Sea Sale 97. The chapters are based on presentations given: The causeway effect: Modification of nearshore thermal regime resulting from causeways; Summertime sea ice intrusions in the Chukchi Sea; The deepwater limit of ice gouging on the Beaufort Sea shelf; Distribution, abundance, migration, harvest, and stock identity of Belukha Whales in the Beaufort Sea; Ringed seals in the Beaufort Sea; Beaufort Sea socioeconomics; The Baffin Island Oil Spill, (BIOS) Project.

  2. Alaska: Beaufort Sea

    Atmospheric Science Data Center

    2014-05-15

    ... to improving our knowledge and understanding of polar weather and long term climate fluctuations. These views from two satellite ... the same geographic area. To identify sea ice types, the National Oceanic and Atmospheric Administration (NOAA) National Ice Center ...

  3. Meteorology of the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Overland, James E.

    2009-01-01

    The unique meteorology of the Beaufort Sea region is dominated by the presence of sea ice and a seasonal swing from a large heat loss in winter to a gain in summer. The primary determinant of this seasonal climate shift is the annual cycle of insolation from a maximum of 500 W/m2 near the summer solstice to darkness in winter, as the Beaufort Sea lies north of Alaska and northwestern Canada beyond 72°N. Even though the Sun angle is low in summer, the length of daylight provides as much energy to the surface as anywhere on the planet. As summer progresses, relative absorption of insolation at the surface increases as the albedo decreases due to snow and ice melt and increased open water area. This annual cycle results in a change from a winter continental-like air mass similar to the adjacent land areas to a summertime marine air mass characterized by low cloud and fogs. In winter the region is also influenced by the polar atmospheric vortex with strong westerly winds centered in the stratosphere, whose presence is felt at the surface. Recent sea ice losses are changing the climatology of the region, with extended periods of increased temperatures through the autumn months.

  4. Submarine pingos in the beaufort sea.

    PubMed

    Shearer, J M; Macnab, R F; Pelletier, B R; Smith, T B

    1971-11-19

    Numerous underwater mounds found on the continental shelf of the Beaufort Sea are thought to be pingos (hills that have a central core of ice) which have formed in the marine environment subsequent to oceanic transgression.

  5. Surface Drifter Study - Beaufort Sea, Alaska.

    DTIC Science & Technology

    1982-07-01

    34._ MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS-1963-A I. REPORT NO: CG- C-33-82 C SURFACE DRIFTER STUDY - BEAUFORT SEA, ALASKA Ivan M. Lissauer ...6.Pefo~rmenq O, latzm, n Code _. Performing Orqanozat.on Report No. 7. AuANr’s) Ivan M. Lissauer 1 R Matthpwq CGRRDC 14/82 9. Pdfom4ing Oregaization...Springfield, Virginia. 63p. Hufford, G.L., I.M. Lissauer and J.P. Welsh, 1976. Movement of spilled oil over the Beaufort Sea Shelf - A forecast. United

  6. Surface current observatons--Beaufort Sea, 1972

    USGS Publications Warehouse

    Barnes, Peter; Garlow, Richard

    1975-01-01

    Sediment transport via water and ice in the Beaufort Sea off northern Alaska is related to the movement of the surficial waters. As development proceeds along the north slope of alaska, a knowledge of the potential drift trajectories of water, ice, sediment and pollutants will be needed. In an attempt to better define the probable paths and rates of transport, 4200 surface drift cards were dropped during the U.S. Coast Guard WEBSEC cruise of August and September, 1972. The results of this release are the subject of this report. Because the data presented here will be used primarily by those interested in solving problems of transport, the emphasis has been placed on data presentation rather than a detailed analysis of the circulation. (Sinha-OEIS)

  7. Gray whale sightings in the Canadian Beaufort Sea, September 2014

    NASA Astrophysics Data System (ADS)

    Iwahara, Yuka; Fujiwara, Amane; Ito, Keizo; Miyashita, Kazushi; Mitani, Yoko

    2016-06-01

    Gray whales (Eschrichtius robustus) are distributed within the productive neritic and estuarine waters of the North Pacific Ocean, the Bering Sea, and adjacent waters of the Arctic Ocean. They migrate to high-latitude feeding grounds each spring. Their main feeding grounds in the Arctic include the Chirikov Basin, the northeastern Chukchi Sea from Pt. Hope to Cape Lisburne and Pt. Lay to Pt. Barrow, and the northwestern Chukchi Sea along the Chukotka coast. Although sightings are rare in the Canadian Beaufort Sea, we observed three gray whales in two groups in this area in September 2014. A mud plume was observed near one of the whales, suggesting the animal had been feeding. In the Alaskan Beaufort Sea, large-scale monitoring of the distributions of marine mammals has been continuously conducted since 1979; however, there has been less monitoring in the Canadian Beaufort Sea. Therefore, it is necessary to record opportunistic sightings, such as those described here.

  8. Ice Types in the Beaufort Sea, Alaska

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Determining the amount and type of sea ice in the polar oceans is crucial to improving our knowledge and understanding of polar weather and long term climate fluctuations. These views from two satellite remote sensing instruments; the synthetic aperture radar (SAR) on board the RADARSAT satellite and the Multi-angle Imaging SpectroRadiometer (MISR), illustrate different methods that may be used to assess sea ice type. Sea ice in the Beaufort Sea off the north coast of Alaska was classified and mapped in these concurrent images acquired March 19, 2001 and mapped to the same geographic area.

    To identify sea ice types, the National Oceanic and Atmospheric Administration (NOAA) National Ice Center constructs ice charts using several data sources including RADARSAT SAR images such as the one shown at left. SAR classifies sea ice types primarily by how the surface and subsurface roughness influence radar backscatter. In the SAR image, white lines delineate different sea ice zones as identified by the National Ice Center. Regions of mostly multi-year ice (A) are separated from regions with large amounts of first year and younger ice (B-D), and the dashed white line at bottom marks the coastline. In general, sea ice types that exhibit increased radar backscatter appear bright in SAR and are identified as rougher, older ice types. Younger, smoother ice types appear dark to SAR. Near the top of the SAR image, however, red arrows point to bright areas in which large, crystalline 'frost flowers' have formed on young, thin ice, causing this young ice type to exhibit an increased radar backscatter. Frost flowers are strongly backscattering at radar wavelengths (cm) due to both surface roughness and the high salinity of frost flowers, which causes them to be highly reflective to radar energy.

    Surface roughness is also registered by MISR, although the roughness observed is at a different spatial scale. Older, rougher ice areas are predominantly backward scattering to

  9. Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea

    USGS Publications Warehouse

    Reimnitz, E.; Dethleff, D.; Nurnberg, D.

    1994-01-01

    The winter ice-regime of the 500 km) from the mainland than in the Beaufort Sea. As a result, the annual freeze-up does not incorporate old, deep-draft ice, and with a lack of compression, such deep-draft ice is not generated in situ, as on the Beaufort Sea shelf. The Laptev Sea has as much as 1000 km of fetch at the end of summer, when freezing storms move in and large (6 m) waves can form. Also, for the first three winter months, the polynya lies inshore at a water depth of only 10 m. Turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice, when compared to conditions in the short-fetched Beaufort Sea. We expect entrainment to occur yearly. Different from the intensely ice-gouged Beaufort Sea shelf, hydraulic bedforms probably dominate in the Laptev Sea. Corresponding with the large volume of ice produced, more dense water is generated in the Laptev Sea, possibly accompanied by downslope sediment transport. Thermohaline convection at the midshelf polynya, together with the reduced rate of bottom disruption by ice keels, may enhance benthic productivity and permit establishment of open-shelf benthic communities which in the Beaufort Sea can thrive only in the protection of barrier islands. Indirect evidence for high benthic productivity is found in the presence of walrus, who also require year-round open water. By contrast, lack of a suitable environment restricts walrus from the Beaufort Sea, although over 700 km farther to the south. We could speculate on other consequences of the different ice regimes in the Beaufort and Laptev Seas, but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the North American Arctic to other shallow Arctic shelf settings. ?? 1994.

  10. The Distribution of Permafrost Beneath the Beaufort Sea Continental Shelf

    NASA Astrophysics Data System (ADS)

    Herman, B. M.

    2011-12-01

    The entire Beaufort Sea continental shelf (CS) is generally believed to have been sub-aerially exposed to temperatures of -12°C during the sea level low-stand that accompanied the last glacial age. After inundation due to rising sea level, the temperature of the seafloor would have been near 0°C. Permafrost formed prior to flooding was generally expected to be ubiquitous at depth due to the relatively recent time of inundation. Seaward of just beyond the Beaufort Sea barrier islands, downhole resistivity and sonic logging in the 10 hydrocarbon exploration wells that have logging at least as shallow as 300 m below sea level (BSL) has not demonstrated evidence of ice-bearing permafrost (IBPF). Indirect evidence of IBPF seaward of the barrier islands is limited to the Belcher well on the eastern Beaufort CS where rock containing gas hydrate was blown from the well while drilling at 754 m BSL (Exlog Canada, 1988). A bottom simulating reflection is observed on the multichannel seismic reflection (MCS) data near the location of the Belcher well, confirming the presence of gas hydrate. From the barrier islands shoreward to the coast, IBPF is indicated by resistivity and sonic logs in all wells having data. The depth to the base of the permafrost in the near shore and onshore areas varies from 200m to over 600 m. Where the top and bottom of the IBPF are observed in the resistivity logs on the barrier islands, the thickness ranges from 100-300 m. MCS data have been collected on the Beaufort CS by the oil industry since the 1970's. IBPF may be inferred from maps of the Dix average velocity (Vave) at a travel time somewhat deeper than the anticipated depth to its base, e.g., 0.75 sec two-way-travel (TWT). Vave is 2.4-3.0 km/sec onshore. In the western Beaufort, Vave decreases rapidly across the shoreline and out to the barrier islands, beyond which it is relatively constant at 1.8 km/sec out to the shelf edge. Vave decreases across the shoreline in the eastern Beaufort, too

  11. Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

    DTIC Science & Technology

    2014-09-30

    seaice.alaska.edu/gi/ LONG-TERM GOALS 1) Determination of the net growth and melt of multiyear (MY) sea ice during its transit through the southern Beaufort...states of the Arctic ice pack OBJECTIVES We have four main scientific objectives: I) Estimation of MY ice volume entrained into the Beaufort Sea from...north of Canada The region north of the Canadian Archipelago contains some of the oldest and thickest ice in the Arctic and the amount of this ice

  12. Movements and distribution of polar bears in the Beaufort sea

    USGS Publications Warehouse

    Amstrup, Steven C.; Durner, G.M.; Stirling, I.; Lunn, N.J.; Messier, F.

    2000-01-01

    We fitted 173 satellite radio collars (platform transmitter terminals) to 121 adult female polar bears in the Beaufort Sea and relocated the bears 44 736 times between 1985 and 1995. We regularly resighted many instrumented bears so that we could ascertain whether changes in movements or distribution were related to reproductive status. Mean short-term movement rates were less than 2 km/h for all classes of bears. Maximum movement rates occurred in winter and early summer. In the southern Beaufort Sea (SBS), net geographic movements from the beginning to the end of each month were smaller for females with cubs of the year than for solitary females, and larger in November than in April, May, or July. In May, June, July, and August, radio-collared bears in the SBS moved north. They moved south in October. In the northern Beaufort Sea (NBS), bears moved north in June and south in March and September. Total annual movements ranged from 1406 to 6203 km. Mean total distances moved each month ranged from 79 to 420 km. Total monthly movements by SBS bears were largest in early winter and smallest in early spring. In the NBS, movements were largest in summer and smallest in winter. In the SBS, females with cubs moved less each month than other females. Annual activity areas ranged from 7264 to 596 800 km2. Monthly activity areas ranged from 88 to 9760 km2. Seasonal fidelity to activity areas of bears captured in all parts of the Beaufort Sea was strongest in summer and weakest in spring.

  13. Heavy-mineral trends in the Beaufort Sea

    USGS Publications Warehouse

    Luepke, Gretchen

    1975-01-01

    Sediments of the Beaufort Sea, off the North Slope of Alaska contain a great variety of heavy minerals. These include garnet, chrome spinel, augite, pigionite, diopside, hornblende, enstatite, hypersthene, epidote, clinozoisite, zoisite, apatite, tourmaline, chloritoid, sphene, zircon, and opaque minerals. Much rarer constituents are glaucophane, lamprobolite, rutile, Kyanite, staurolite, and riebeckite. Garnet increases in abundance from east to west, which corresponds to a similar increase in garnet abundance in coastal outcrops of the Gubik Formation sands. Only garnet and iron-stained aggregates appear to have source-related distribution patterns. The other heavy minerals lack distinct distributive provinces, reflecting an environment dominated by intense mixing by ice-gouging and bioturbation and a homogenous source area. Waves and currents are not strong enough to sort sediments at depths greater than 10 m except during summer storms. The source of the Beaufort Sea heavy minerals is dominated by contributions from the Alaskan North Slope deposits of Tertiary and younger age. The Colville River, largest in the region, is probably the most influential in transporting sediments, but because of wave and current-mixing of sediments on the shelf, exact contributions from each river drainage cannot be ascertained. Coastal erosion of the Gubik Formation is probably at least as important as the Colville River in supplying heavy minerals to the Beaufort Sea. (Sinha-OEIS)

  14. Recent changes in sea ice area flux through the Beaufort Sea during the summer

    NASA Astrophysics Data System (ADS)

    Howell, Stephen E. L.; Brady, Michael; Derksen, Chris; Kelly, Richard E. J.

    2016-04-01

    Over the annual cycle, sea ice is sequestered from the Canadian Basin and transported through the Beaufort Sea toward the Chukchi Sea. In recent years, the Beaufort Sea has experienced considerable ice loss during the summer, which may be indicative of recent changes to this process. In order to investigate this, we quantify the sea ice area flux using RADARSAT from 1997 to 2014 at three gates in Beaufort Sea: the Canadian Basin (entrance), mid-Beaufort (midpoint), and Chukchi (exit). There was a mean annual flux of 42 ± 56 × 103 km2 at the Canadian Basin gate, 94 ± 92 × 103 km2 at the mid-Beaufort gate and -83 ± 68 × 103 km2 at the Chukchi gate (positive and negative flux signs correspond to ice inflow and outflow, respectively). The majority of ice transport in Beaufort Sea was found to occur from October to May providing replenishment for ice lost during the summer months. The cross-strait gradient in sea level pressure explains ˜40% of the variance in the ice area flux at the gates. Remarkably, the mean July-October net sea ice area flux at the Chukchi gate decreased by ˜80% from 2008 to 2014 relative to 1997-2007 and became virtually ice-free every year since 2008. This reduction was associated with younger (thinner) ice that was unable to survive the summer melt season when either being sequestered from the Canadian Basin and transported through Beaufort Sea during the melt season (2008-2011) or remaining immobile and present in the vicinity of the Chukchi gate during the melt season (2012-2014).

  15. Aerial Surveys of Endangered Whales in the Beaufort Sea, Chukchi Sea, and Northern Bering Sea.

    DTIC Science & Technology

    1981-06-01

    of Kivalina. The entire area from this point to the village of Wales was icebound. Figure 3 shows the typical ice conditions of the Bering Sea...area extending across the Bering Straits from Cape Prince of Wales to the north end of Little Diomede Island. Large concentrations of pan ice with a 7...ice conditions across the main area of sightings between Wales and Little Diomede Island throughout the survey effort. 8 !. I. I Beaufort Sea I.Brrow

  16. Polar bear maternity denning in the Beaufort Sea

    USGS Publications Warehouse

    Amstrup, S.; Gardner, C.

    1994-01-01

    The distribution of polar bears (Ursus maritimus) is circumpolar in the NOrthern Hemisphere, but known locations of maternal dens are concentrated in relatively few, widely scattered locations. Denning is either uncommon or unknown within gaps. To understand effects of industrial development and propose increases in hunting, the temporal and spatial distribution of denning in the Beaufort Sea must be known. We caputred and radiocollared polar bears between 1981 and 1991 and determined tht denning in the Beaufort Sea region was sufficient to account for the estimated population there. Of 90 dend, 48 were on drifting pack ice, 38 on land, and 4 on land-fast ice. The portions of dens on land was higher (P= 0.029) in later compared with earlier years of the study. Bears denning on pack ice drifting as far as 997 km (x=385km) while in dens. there was no difference in cun production by bears denning on land and pack ice (P =0.66). Mean entry and exit dates were 11 November and 5 April for land dens and 22 November and 26 March for pack-ice dens. Female polar bears captured in the Beaufort Sea appeared to be isolated from those caught eat of Cape Bathurst in Canada. Of 35 polar bears that denned along the mainland coast of Alaska and Canada 80% denned between 137 00'W snf 146 59'W. Bears followed to >1 den did not reuse sites and consecutive dens were 20-1,304 km apart. However radio-collared bears are largely faithful to substrate (pack-ice, land, and land-fast ice) and the general geographic area of previous dens. Bears denning on land may be vunerable to human activities such as hunting and industrial development. However, predictable denning chronology and alck of site fidelity indicate that many potential impacts on denning polar bears could be mitigated.

  17. Ice gouge processes in the Alaskan Beaufort Sea

    USGS Publications Warehouse

    Rearic, Douglas M.; Ticken, Edward J.

    1988-01-01

    A generalized picture of ice gouge characteristics from shallow inshore depths to the outer shelf at about 60 m of water is presented. Data from recent studies show that the size and quantity of gouging increases in an offshore direction to depths of about 45 m where this trend then reverses and the features decrease in size and quantity as the shelf break is approached. Ice gouges are oriented east-west and this suggests that most gouging is caused by ice approaching from the east, possibly driven by the Beaufort Sea gyre. The most intense gouging occurs in the stamukhi zone, between 20 and 40 m of water, and is caused by a high rate of ice keel production owing to shearing forces between mobile and stable sea ice. Inshore of the stamukhi zone, ice gouging still presents a significant hazard but their greatly decreased size and number make it possible to design against this hazard.

  18. Effects of Mackenzie River Discharge and Bathymetry on Sea Ice in the Beaufort Sea

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Hall, D. K.; Rigor, I. G; Li, P.; Neumann, G.

    2014-01-01

    Mackenzie River discharge and bathymetry effects on sea ice in the Beaufort Sea are examined in 2012 when Arctic sea ice extent hit a record low. Satellite-derived sea surface temperature revealed warmer waters closer to river mouths. By 5 July 2012, Mackenzie warm waters occupied most of an open water area about 316,000 sq km. Surface temperature in a common open water area increased by 6.5 C between 14 June and 5 July 2012, before and after the river waters broke through a recurrent landfast ice barrier formed over the shallow seafloor offshore the Mackenzie Delta. In 2012, melting by warm river waters was especially effective when the strong Beaufort Gyre fragmented sea ice into unconsolidated floes. The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean, constituting a stark contrast to the Antarctic that has no such rivers to affect sea ice.

  19. Pressure Ridge Keel Shapes in the Chukchi and Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Valenti, V. A.; Mahoney, A. R.; Metzger, A.; Eicken, H.

    2014-12-01

    Abstract: Recent aspirations for offshore development in the Chukchi and Beaufort seas, off the North Slope of Alaska, have precipitated the need of additional information for various sea-ice parameters. Of specific interest to engineers and regulatory agencies are the magnitudes of parameters representative of major hazards with a low expectation of occurring over some timeframe. The thickness and width of large pressure ridges that may impact offshore structures is of particular interest. Here, we analyze an extensive dataset from moored ice profiling sonars (IPSs) and acoustic Doppler current profilers (ADCPs) deployed in the vicinity of offshore oil-and-gas lease areas in the US portions of the Chukchi and Beaufort Seas. In all, we examine 16 annual time series of ice draft and velocity from six different mooring locations over five years. Using an automated algorithm, we identify individual pressure ridge keels based on deviations in ice draft from surrounding level ice and derive measurements of the maximum depth and shape of each. Of particular note, and contrary to many idealized ridges portrayed in the literature, we find that flat-bottomed keels are rare in this region. Since the orientation of each ridge as it passes over the mooring is unknown it is not possible to directly measure the precise width. Instead we bin the keels by maximum depth and find the modal width value for each depth bin. Finding that most keels have broadly the same triangular cross-section, we assume the modal width value corresponds to cases when the ridge passes over the mooring approximately perpendicular to its axis. Using this approach, we find a constant ratio between maximum keel depth and width, corresponding to a mean keel slope of around 33 degrees. This is somewhat steeper than is commonly found in literature. We also analyze the relationship between keel depth and drift speed, but find no statistically significant dependence.

  20. Use of the Beaufort Sea by king eiders breeding on the North Slope of Alaska

    USGS Publications Warehouse

    Phillips, Laura M.; Powell, A.N.; Taylor, E.J.; Rexstad, E.A.

    2007-01-01

    We estimated areas used by king eiders (Somateria spectabilis) in the Alaskan Beaufort Sea, how distributions of used areas varied, and characteristics that explained variation in the number of days spent at sea, to provide regulatory agencies with baseline data needed to minimize impacts of potential offshore oil development. We implanted sixty king eiders with satellite transmitters at nesting areas on the North Slope of Alaska, USA, in 2002-2004. More than 80% of marked eiders spent >2 weeks staging offshore prior to beginning a postbreeding molt migration. During postbreeding staging and migration, male king eiders had much broader distributions in the Alaskan Beaufort Sea than female eiders, which were concentrated in Harrison and Smith Bays. Distribution did not vary by sex during spring migration in the year after marking. Shorter residence times of eiders and deeper water at locations used during spring migration suggest the Alaskan Beaufort Sea might not be as critical a staging area for king eiders during prebreeding as it is postbreeding. Residence time in the Beaufort Sea varied by sex, with female king eiders spending more days at sea than males in spring and during postbreeding. We conclude the Alaskan Beaufort Sea is an important staging area for king eiders during postbreeding, and eider distribution should be considered by managers when mitigating for future offshore development. We recommend future studies examine the importance of spring staging areas outside the Alaskan Beaufort Sea.

  1. Shelfbreak current over the Canadian Beaufort Sea continental slope: Wind-driven events in January 2005

    NASA Astrophysics Data System (ADS)

    Dmitrenko, Igor A.; Kirillov, Sergei A.; Forest, Alexandre; Gratton, Yves; Volkov, Denis L.; Williams, William J.; Lukovich, Jennifer V.; Belanger, Claude; Barber, David G.

    2016-04-01

    The shelfbreak current over the Beaufort Sea continental slope is known to be one of the most energetic features of the Beaufort Sea hydrography. In January 2005, three oceanographic moorings deployed over the Canadian (eastern) Beaufort Sea continental slope simultaneously recorded two consecutive shelfbreak current events with along-slope eastward bottom-intensified flow up to 120 cm s-1. Both events were generated by the local wind forcing associated with two Pacific-born cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago. Over the mooring array, the associated westerly wind exceeded 15 m s-1. These two cyclones generated storm surges along the Beaufort Sea coast with sea surface height (SSH) rising up to 1.4 m following the two westerly wind maxima. We suggest that the westerly along-slope wind generated a surface Ekman onshore transport. The associated SSH increase over the shelf produced a cross-slope pressure gradient that drove an along-slope eastward geostrophic current, in the same direction as the wind. This wind-driven barotropic flow was superimposed on the background baroclinic bottom-intensified shelfbreak current that consequently amplified. Summer-fall satellite altimetry data for 1992-2013 show that the SSH gradient in the southeastern Beaufort Sea is enhanced over the upper continental slope in response to frequent storm surge events. Because the local wind forcing and/or sea-ice drift could not explain the reduction of sea-ice concentration over the Beaufort Sea continental slope in January 2005, we speculate that wind-driven sea level fluctuations may impact the sea-ice cover in winter.

  2. Methane in coastal sea water, sea ice, and bottom sediments, Beaufort Sea, Alaska

    USGS Publications Warehouse

    Lorenson, T.D.; Kvenvolden, Keith A.

    1995-01-01

    This report summarizes data acquired from 1990 to 1994 for the gas-hydrate portion of the USGS project 'Permafrost and gas hydrate as possible sources of methane' of the USGS Global Change and Climate History program. The objective of this project has been to test the hypothesis that gas hydrate deposits of the Beaufort Sea continental shelf are destabilized by the ~10?C temperature increase that has resulted from the Holocene transgression of the Arctic Ocean. To test this idea we have selected an area off the north coast of Alaska centered on Harrison Bay. We have measured the concentration of methane in surficial sediments, in the water column when ice is present and absent, and in seasonal sea ice. Our results show that more methane is present in the water when ice is present than when ice is absent, and that methane is also present within the ice itself, often at higher concentrations than in the water. Thus the Beaufort Sea shelf of Alaska is a seasonal source of methane. The primary source of this methane has not yet been defined, but gas hydrate is a reasonable candidate.

  3. Sea Ice Floe Size Distribution in the Beaufort Sea Measured by ERS-1 SAR (abstract)

    NASA Technical Reports Server (NTRS)

    Holt, B.; Martin, S.

    1996-01-01

    Model results indicate that understanding summer heat balance and freshwater balance in the polar oceans requires knowledge of how much goes into vertical and lateral sea ice melt. In addition to thickness, two of the key ice parameters that affect melt rate are ice concentration and floe size. Smaller ice floes and more open water enables more heat to go into lateral melt preferentially to vertical melt, thereby enhancing warming up the upper ocean and increasing stratification. Using ERS-1 SAR imagery along two areas, one in the Beaufort Sea and another in the Chukchi Sea, floe size distributions were obtained during the summer period in 1992. Comparisons will be made of floe distributions, together with meteorological and buoy measurements, to examine the differences between an ice sink region (Chukchi) and a multiyear ice region (Beaufort) in the summer melt process.

  4. The epipelagic fish community of Beaufort Sea coastal waters, Alaska

    USGS Publications Warehouse

    Jarvela, L.E.; Thorsteinson, L.K.

    1999-01-01

    A three-year study of epipelagic fishes inhabiting Beaufort Sea coastal waters in Alaska documented spatial and temporal patterns in fish distribution and abundance and examined their relationships to thermohaline features during summer. Significant interannual, seasonal, and geographical differences in surface water temperatures and salinities were observed. In 1990, sea ice was absent and marine conditions prevailed, whereas in 1988 and 1991, heavy pack ice was present and the dissolution of the brackish water mass along the coast proceeded more slowly. Arctic cod, capelin, and liparids were the most abundant marine fishes in the catches, while arctic cisco was the only abundant diadromous freshwater species. Age-0 arctic cod were exceptionally abundant and large in 1990, while age-0 capelin dominated in the other years. The alternating numerical dominances of arctic cod and age-0 capelin may represent differing species' responses to wind-driven oceanographic processes affecting growth and survival. The only captures of age-0 arctic cisco occurred during 1990. Catch patterns indicate they use a broad coastal migratory corridor and tolerate high salinities. As in the oceanographic data, geographical anti temporal patterns were apparent in the fish catch data, but in most cases these patterns were not statistically testable because of excessive zero catches. The negative binomial distribution appeared to be a suitable statistical descriptor of the aggregated catch patterns for the more common species.

  5. Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

    DTIC Science & Technology

    2014-09-30

    Cover in the Beaufort and Chukchi Seas Dale A. Lawrence and James Maslanik Aerospace Engineering Sciences University of Colorado Boulder, CO...OBJECTIVES The main objective of the University of Colorado portion of the project is to adapt an existing low cost, expendable small unmanned...University of Colorado ,325 Broadway,Boulder,CO,80305 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS

  6. Habitat selection by two beluga whale populations in the Chukchi and Beaufort seas.

    PubMed

    Hauser, Donna D W; Laidre, Kristin L; Stern, Harry L; Moore, Sue E; Suydam, Robert S; Richard, Pierre R

    2017-01-01

    There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice conditions. We established habitat selection models that incorporated daily sea ice measures (sea ice concentration, proximity to ice edge and dense ice) and bathymetric features (slope, depth, proximity to the continental slope, Barrow Canyon, and shore) to establish quantitative estimates of habitat use for the Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') populations. We applied 'used v. available' resource selection functions to locations of 65 whales tagged from 1993-2012, revealing large variations in seasonal habitat selection that were distinct between sex and population groups. Chukchi whales of both sexes were predicted to use areas in close proximity to Barrow Canyon (typically <200 km) as well as the continental slope in summer, although deeper water and denser ice were stronger predictors for males than females. Habitat selection differed more between sexes for Beaufort belugas. Beaufort males selected higher ice concentrations (≥40%) than females (0-40%) in July-August. Proximity to shore (<200 km) strongly predicted summer habitat of Beaufort females, while distance to the ice edge was important for male habitat selection, especially during westward migration in September. Overall, our results indicate that sea ice variables were rarely the primary drivers of beluga summer-fall habitat selection. While diminished sea ice may indirectly affect belugas through changes in the ecosystem, associations with bathymetric features that affect prey availability seemed key to habitat selection during summer and fall. These results provide a

  7. Pigment signatures of phytoplankton communities in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Coupel, P.; Matsuoka, A.; Ruiz-Pino, D.; Gosselin, M.; Claustre, H.; Marie, D.; Tremblay, J.-É.; Babin, M.

    2014-10-01

    Phytoplankton are expected to respond to recent environmental changes of the Arctic Ocean. In terms of bottom-up control, modifying the phytoplankton distribution will ultimately affect the entire food web and carbon export. However, detecting and quantifying change in phytoplankton communities in the Arctic Ocean remains difficult because of the lack of data and the inconsistent identification methods used. Based on pigment and microscopy data sampled in the Beaufort Sea during summer 2009, we optimized the chemotaxonomic tool CHEMTAX for the assessment of phytoplankton community composition in an Arctic setting. The geographical distribution of the main phytoplankton groups was determined with clustering methods. Four phytoplankton assemblages were determined and related to bathymetry, nutrients and light availability. Surface waters across the whole survey region were dominated by prasinophytes and chlorophytes, whereas the subsurface chlorophyll maximum was dominated by the centric diatoms Chaetoceros socialis on the shelf and by two populations of nanoflagellates in the deep basin. Microscopic count showed a high contribution of the heterotrophic dinoflagellates Gymnodinium and Gyrodinium spp. to total carbon biomass, suggesting high grazing activity at this time of the year. However, CHEMTAX was unable to detect these dinoflagellates because they lack peridinin. The inclusion in heterotrophic dinoflagellates of the pigments of their prey potentially leads to incorrect group assignments and some misinterpretation of CHEMTAX. Thanks to the high reproducibility of pigment analysis, our results can serve as a baseline to assess change and spatial or temporal variability in phytoplankton populations.

  8. Pigment signatures of phytoplankton communities in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Coupel, P.; Matsuoka, A.; Ruiz-Pino, D.; Gosselin, M.; Marie, D.; Tremblay, J.-É.; Babin, M.

    2015-02-01

    Phytoplankton are expected to respond to recent environmental changes of the Arctic Ocean. In terms of bottom-up control, modifying the phytoplankton distribution will ultimately affect the entire food web and carbon export. However, detecting and quantifying changes in phytoplankton communities in the Arctic Ocean remains difficult because of the lack of data and the inconsistent identification methods used. Based on pigment and microscopy data sampled in the Beaufort Sea during summer 2009, we optimized the chemotaxonomic tool CHEMTAX (CHEMical TAXonomy) for the assessment of phytoplankton community composition in an Arctic setting. The geographical distribution of the main phytoplankton groups was determined with clustering methods. Four phytoplankton assemblages were determined and related to bathymetry, nutrients and light availability. Surface waters across the whole survey region were dominated by prasinophytes and chlorophytes, whereas the subsurface chlorophyll maximum was dominated by the centric diatoms Chaetoceros socialis on the shelf and by two populations of nanoflagellates in the deep basin. Microscopic counts showed a high contribution of the heterotrophic dinoflagellates Gymnodinium and Gyrodinium spp. to total carbon biomass, suggesting high grazing activity at this time of the year. However, CHEMTAX was unable to detect these dinoflagellates because they lack peridinin. In heterotrophic dinoflagellates, the inclusion of the pigments of their prey potentially leads to incorrect group assignments and some misinterpretation of CHEMTAX. Thanks to the high reproducibility of pigment analysis, our results can serve as a baseline to assess change and spatial or temporal variability in several phytoplankton populations that are not affected by these misinterpretations.

  9. Divergent patterns of recent sea ice cover across the Bering, Chukchi, and Beaufort seas of the Pacific Arctic Region

    NASA Astrophysics Data System (ADS)

    Frey, Karen E.; Moore, G. W. K.; Cooper, Lee W.; Grebmeier, Jacqueline M.

    2015-08-01

    Over the past three decades of the observed satellite record, there have been significant changes in sea ice cover across the Bering, Chukchi, and Beaufort seas of the Pacific Arctic Region (PAR). Satellite data reveal that patterns in sea ice cover have been spatially heterogeneous, with significant declines in the Chukchi and Beaufort seas, yet more complex multi-year variability in the Bering Sea south of St. Lawrence Island. These patterns in the Chukchi and Beaufort seas have intensified since 2000, indicating a regime shift in sea ice cover across the northern portion of the PAR. In particular, satellite data over 1979-2012 reveal localized decreases in sea ice presence of up to -1.64 days/year (Canada Basin) and -1.24 days/year (Beaufort Sea), which accelerated to up to -6.57 days/year (Canada Basin) and -12.84 days/year (Beaufort Sea) over the 2000-2012 time period. In contrast, sea ice in the Bering Sea shows more complex multi-year variability with localized increases in sea ice presence of up to +8.41 days/year since 2000. The observed increases in sea ice cover since 2000 in the southern Bering Sea shelf region are observed in wintertime, whereas sea ice losses in the Canada Basin and Beaufort Sea have occurred during summer. We further compare sea ice variability across the region with the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) wind and air temperature fields to determine the extent to which this recent variability is driven by thermal vs. wind-driven processes. Results suggest that for these localized areas that are experiencing the most rapid shifts in sea ice cover, those in the Beaufort Sea are primarily wind driven, those offshore in the Canada Basin are primarily thermally driven, and those in the Bering Sea are influenced by elements of both. Sea ice variability (and its drivers) across the PAR provides critical insight into the forcing effects of recent shifts in climate and its likely

  10. Behavior, disturbance responses and distribution of bowhead whales Balaena mysticetus in the eastern Beaufort Sea, 1980-84: a summary

    SciTech Connect

    Richardson, W.J.; Greene, C.R.; Wuersig, B.

    1985-06-01

    The behavior of bowhead whales summering in the eastern (Canadian) Beaufort Sea, and their reactions to industrial activities, were studied during five summers in the report. The objective was to provide data needed to assess the possible effects of offshore oil exploration and development in the Alaskan Beaufort Sea on this endangered species.

  11. Habitat selection by two beluga whale populations in the Chukchi and Beaufort seas

    PubMed Central

    Laidre, Kristin L.; Stern, Harry L.; Moore, Sue E.; Suydam, Robert S.; Richard, Pierre R.

    2017-01-01

    There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice conditions. We established habitat selection models that incorporated daily sea ice measures (sea ice concentration, proximity to ice edge and dense ice) and bathymetric features (slope, depth, proximity to the continental slope, Barrow Canyon, and shore) to establish quantitative estimates of habitat use for the Eastern Chukchi Sea (‘Chukchi’) and Eastern Beaufort Sea (‘Beaufort’) populations. We applied ‘used v. available’ resource selection functions to locations of 65 whales tagged from 1993–2012, revealing large variations in seasonal habitat selection that were distinct between sex and population groups. Chukchi whales of both sexes were predicted to use areas in close proximity to Barrow Canyon (typically <200 km) as well as the continental slope in summer, although deeper water and denser ice were stronger predictors for males than females. Habitat selection differed more between sexes for Beaufort belugas. Beaufort males selected higher ice concentrations (≥40%) than females (0–40%) in July-August. Proximity to shore (<200 km) strongly predicted summer habitat of Beaufort females, while distance to the ice edge was important for male habitat selection, especially during westward migration in September. Overall, our results indicate that sea ice variables were rarely the primary drivers of beluga summer-fall habitat selection. While diminished sea ice may indirectly affect belugas through changes in the ecosystem, associations with bathymetric features that affect prey availability seemed key to habitat selection during summer and fall. These

  12. Model of inner shelf shoal development, Beaufort Sea, Alaska

    SciTech Connect

    Lowry, P.; Nummedal, D.; Reimnitz, E.

    1985-01-01

    At least two types of inner shelf shoals exist in the Beaufort Sea, Alaska. One type is located up to 40 km from the shoreline in an average water depth of 20m and oriented obliquely to the coast. A second type of shoals occur adjacent to existing barrier islands where minimum water depth over the shoal crest may be as little as 30-50cm. The development of shallow water shoals is believed to be a result of barrier island submergence. Dinkum Sands is an example of a shallow water shoal. This linear sand body is located between Cross and Narwhal Islands, 25km northeast of Prudhoe Bay. The shoal complex is 8 km long and less than 2 km wide and has a maximum relief of 5m. Historical data reveal submergence of an island over at least a 25 year period. The proposed initial stage of shoal development occurs when longshore sediment transport between barrier islands is disrupted by numerous events of downdrift tidal inlet breaching. Reduction in the amount of available sediment to each island results in significant coastal erosion (stage 2), manifest as a landward migration of the shoreline and a reduction in barrier elevation. The final stage of the model is barrier submergence. At present the greatest accumulation of sediment on Dinkum Sands occur at the distal extremities of the shoal. These are believed to represent the location of recurved spits at either end of the island prior to submergence. Application of the submergence model to explain deepwater shoal development must await the collection of shallow (10m) whole core data.

  13. Aerial monitoring of marine waterfowl in the Alaskan Beaufort Sea.

    PubMed

    Johnson, Stephen R; Noel, Lynn E; Gazey, William J; Hawkes, Virgil C

    2005-09-01

    The purpose of this study was to design and test a monitoring protocol for marine waterfowl in the central Alaskan Beaufort Sea. The study provides an important case-study of how a long-term monitoring program may be affected by unanticipated human disturbances. Because of its overwhelming and widespread abundance, relatively sedentary behavior, ease in counting, and the extensive historical database, the long-tailed duck (Clangula hyemalis) was selected as the focal species. Two null hypotheses were formulated concerning potential changes in the numbers and distribution of long-tailed ducks in relation to disturbance in an industrial study area, compared to a reference study area located about 50 km to the east. A 9-year historical database (1977-1984, 1989) of long-tailed duck densities and other important data recorded during systematic aerial surveys was analyzed retrospectively using multiple regression techniques. The retrospective analyses determined which of several predictor variables recorded were significantly related to long-tailed duck density. Separate analyses were conducted for two periods: (1) the overall period when long-tailed ducks were present in the lagoon study areas, and (2) the shorter adult male molt period. The results of the two analyses indicated that 57% and 68%, respectively, of the total variation in long-tailed duck density during the two periods could be explained by variables recorded during the surveys. Predictor variables representing habitat, day of the year, time of day, amount of ice, and wave height recorded on-transect during surveys were most closely associated with long-tailed duck density. Measurement error during the surveys, and influences outside the study area such as nesting success in tundra habitats and mortality during migration and in over-wintering areas likely also had strong influences on the results, but these factors were not measurable in our study. Based on results of the retrospective analyses, a long

  14. Mud Volcanoes from the Beaufort Sea to the South China Sea

    NASA Astrophysics Data System (ADS)

    Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Dallimore, S.; Melling, H.; Liu, C. S.; Anderson, K.; Gwiazda, R.

    2015-12-01

    The detailed morphology of five submarine mud volcanoes were surveyed using an Autonomous Underwater Vehicle (AUV) developed at the Monterey Bay Aquarium Research Institute. Mud volcanoes are constructional features built by extrusion of gas, subsurface fluids and fine-grained sediment. Two surveys covering four submarine mud volcanoes were conducted on the CCGS Sir Wilfred Laurier in the Beaufort Sea in the Canadian Arctic. A survey of one mud volcano was conducted on the Taiwanese Ocean Research V in the South China Sea, SE of Taiwan. The AUV carried a multibeam sonar, a 1-6 kHz chirp sub-bottom profiler, and a110 kHz sidescan, and obtained overlapping multibeam bathymetric coverage at a vertical resolution of 0.15 m with a horizontal footprint of 0.9 m and chirp seismic-reflection profiles with a vertical resolution of 0.11 m. Mud volcanoes were either flat topped or conical. The conical mud volcano off Taiwan had a diameter of ~2 km and 10° side slopes; the conical feature in the Beaufort Sea had a diameter of ~1.5 km and 4° side slopes. The sides of the conical mud volcanoes were smooth, suggesting they were formed by sediment flows that emanate from a vent on their crests. The flanks of the conical mud volcanoes characteristically had very low acoustic reflectivity, but one single high reflectivity trail from the crest of the Beaufort Sea mud volcano indicates a recent flow. Three mud volcanoes in the Beaufort Sea formed circular, flat-topped plateaus that are up to ~1.1 km in diameter and elevated up to 30 m from the surrounding seafloor. The fine scale morphology and reflectivity on these plateaus show low relief, concentric, and ovoid circles that appear to be mud boils probably associated with eruptive events of varying ages at shifting vent sites. The different mud volcano shapes are attributed to variations in the viscosity of the erupting sediment slurries and may represent a sequential morphology, which is altered by shifts in venting position over

  15. Distribution, Abundance, Behavior, and Bioacoustics of Endangered Whales in the Alaskan Beaufort and Eastern Chukchi Seas, 1979-86.

    DTIC Science & Technology

    1987-07-01

    hauled out on the ice (Appendix A, N780: Flight 43). Three walruses , all swimming, were seen in the western Alaskan Beaufort Sea in mid- September...develop relatively nearshore in the Chukchi Sea , but offshore and well north of oil exploration activities in the Alaskan Beaufort Sea (Braham et al., 1984...band of open water between the shorefast and heavy ice (>9596) west of Barrow in the northeastern Chukchi Sea . Ice

  16. Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline

    USGS Publications Warehouse

    Bromaghin, Jeffrey F.; McDonald, Trent L.; Stirling, Ian; Derocher, Andrew E.; Richardson, Evan S.; Regehr, Eric V.; Douglas, David C.; Durner, George M.; Atwood, Todd C.; Amstrup, Steven C.

    2015-01-01

    In the southern Beaufort Sea of the United States and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears (Ursus maritimus). Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark–recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25–50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606–1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival. A refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary to improve projections of their future status and facilitate development of management strategies.

  17. Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline.

    PubMed

    Bromaghin, Jeffrey F; Mcdonald, Trent L; Stirling, Ian; Derocher, Andrew E; Richardson, Evan S; Regehr, Eric V; Douglas, David C; Durner, George M; Atwood, Todd; Amstrup, Steven C

    2015-04-01

    In the southern Beaufort Sea of the United States and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears (Ursus maritimus). Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark-recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25-50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606-1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival. A refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary to improve projections of their future status and facilitate development of management strategies.

  18. Polar Bear Population Status in the Southern Beaufort Sea

    USGS Publications Warehouse

    Regehr, Eric V.; Amstrup, Steven C.; Stirling, Ian

    2006-01-01

    Polar bears depend entirely on sea ice for survival. In recent years, a warming climate has caused major changes in the Arctic sea ice environment, leading to concerns regarding the status of polar bear populations. Here we present findings from long-term studies of polar bears in the southern Beaufort Sea (SBS) region of the U.S. and Canada, which are relevant to these concerns. We applied open population capture-recapture models to data collected from 2001 to 2006, and estimated there were 1,526 (95% CI = 1,211; 1,841) polar bears in the SBS region in 2006. The number of polar bears in this region was previously estimated to be approximately 1,800. Because precision of earlier estimates was low, our current estimate of population size and the earlier ones cannot be statistically differentiated. For the 2001-06 period, the best fitting capture-recapture model provided estimates of total apparent survival of 0.43 for cubs of the year (COYs), and 0.92 for all polar bears older than COYs. Because the survival rates for older polar bears included multiple sex and age strata, they could not be compared to previous estimates. Survival rates for COYs, however, were significantly lower than estimates derived in earlier studies (P = 0.03). The lower survival of COYs was corroborated by a comparison of the number of COYs per adult female for periods before (1967-89) and after (1990-2006) the winter of 1989-90, when warming temperatures and altered atmospheric circulation caused an abrupt change in sea ice conditions in the Arctic basin. In the latter period, there were significantly more COYs per adult female in the spring (P = 0.02), and significantly fewer COYs per adult female in the autumn (P < 0.001). Apparently, cub production was higher in the latter period, but fewer cubs survived beyond the first 6 months of life. Parallel with declining survival, skull measurements suggested that COYs captured from 1990 to 2006 were smaller than those captured before 1990

  19. Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    George, John C.; Druckenmiller, Matthew L.; Laidre, Kristin L.; Suydam, Robert; Person, Brian

    2015-08-01

    We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering-Chukchi-Beaufort Seas (BCB) stock to estimate various body condition indices (BCI's) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989-2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI's was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the

  20. Physical processes contributing to an ice free Beaufort Sea during September 2012

    NASA Astrophysics Data System (ADS)

    Babb, D. G.; Galley, R. J.; Barber, D. G.; Rysgaard, S.

    2016-01-01

    During the record September 2012 sea ice minimum, the Beaufort Sea became ice free for the first time during the observational record. Increased dynamic activity during late winter enabled increased open water and seasonal ice coverage that contributed to negative sea ice anomalies and positive solar absorption anomalies which drove rapid bottom melt and sea ice loss. As had happened in the Beaufort Sea during previous years of exceptionally low September sea ice extent, anomalous solar absorption developed during May, increased during June, peaked during July, and persisted into October. However in situ observations from a single floe reveal less than 78% of the energy required for bottom melt during 2012 was available from solar absorption. We show that the 2012 sea ice minimum in the Beaufort was the result of anomalously large solar absorption that was compounded by an arctic cyclone and other sources of heat such as solar transmission, oceanic upwelling, and riverine inputs, but was ultimately made possible through years of preconditioning toward a younger, thinner ice pack. Significant negative trends in sea ice concentration between 1979 and 2012 from June to October, coupled with a tendency toward earlier sea ice reductions have fostered a significant trend of +12.9 MJ m-2 yr-1 in cumulative solar absorption, sufficient to melt an additional 4.3 cm m-2 yr-1. Overall through preconditioning toward a younger, thinner ice pack the Beaufort Sea has become increasingly susceptible to increased sea ice loss that may render it ice free more frequently in coming years.

  1. Fish communities across a spectrum of habitats in the western Beaufort Sea and Chukchi Sea

    NASA Astrophysics Data System (ADS)

    Logerwell, E.; Busby, M.; Carothers, C.; Cotton, S.; Duffy-Anderson, J.; Farley, E.; Goddard, P.; Heintz, R.; Holladay, B.; Horne, J.; Johnson, S.; Lauth, B.; Moulton, L.; Neff, D.; Norcross, B.; Parker-Stetter, S.; Seigle, J.; Sformo, T.

    2015-08-01

    The increased scientific interest in the Arctic due to climate change and potential oil and gas development has resulted in numerous surveys of Arctic marine fish communities since the mid-2000s. Surveys have been conducted in nearly all Arctic marine fish habitats: from lagoons, beaches and across the continental shelf and slope. This provides an opportunity only recently available to study Arctic fish communities across a spectrum of habitats. We examined fish survey data from lagoon, beach, nearshore benthic, shelf pelagic and shelf benthic habitats in the western Beaufort Sea and Chukchi Sea. Specifically, we compare and contrast relative fish abundance and length (a proxy for age) among habitats and seas. We also examined ichthyoplankton presence/absence and abundance of dominant taxa in the shelf habitat. Our synthesis revealed more similarities than differences between the two seas. For example, our results show that the nearshore habitat is utilized by forage fish across age classes, and is also a nursery area for other species. Our results also indicated that some species may be expanding their range to the north, for example, Chinook Salmon. In addition, we documented the presence of commercially important taxa such as Walleye Pollock and flatfishes (Pleuronectidae). Our synthesis of information on relative abundance and age allowed us to propose detailed conceptual models for the life history distribution of key gadids in Arctic food webs: Arctic and Saffron Cod. Finally, we identify research gaps, such as the need for surveys of the surface waters of the Beaufort Sea, surveys of the lagoons of the Chukchi Sea, and winter season surveys in all areas. We recommend field studies on fish life history that sample multiple age classes in multiple habitats throughout the year to confirm, resolve and interpret the patterns in fish habitat use that we observed.

  2. A practical method for long-range forecasting of ice severity in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Drobot, Sheldon D.; Maslanik, James A.

    2002-04-01

    A linear regression model is used to forecast end of summer ice conditions in the Beaufort Sea with a few months lead-time. The model retains four sea ice and atmospheric parameters, where decreased spring total and winter multiyear ice concentrations, negative October East Atlantic phases, and positive March North Atlantic Oscillation phases are associated with lighter sea ice conditions. Monte Carlo simulations suggest that the results are not adversely affected by artificial skill, while Durbin-Watson and Variance Inflation Factor statistics imply the final model is statistically valid. Cross validation diagnostics indicate that variations in the four predictors are related to 85% of the variation in sea ice conditions, suggesting that a relatively simple ice-atmosphere statistical model can be used to forecast end of summer ice conditions in the Beaufort Sea.

  3. Microsatellite DNA and mitochondrial DNA variation in polar bears (Ursus maritimus) from the Beaufort and Chukchi seas, Alaska

    USGS Publications Warehouse

    Cronin, M.A.; Amstrup, Steven C.; Scribner, K.T.

    2006-01-01

    Radiotelemetry data have shown that polar bears (Ursus maritimus Phipps, 1774) occur in separate subpopulations in the Chukchi Sea and the southern Beaufort Sea. However, segregation is not absolute, and there is overlap of ranges of animals in each subpopulation. We used genetic variation at eight microsatellite DNA loci and mitochondrial DNA (mtDNA) to further assess the degree of spatial structure of polar bears from the Chukchi and southern Beaufort seas. Microsatellite allele frequencies and mtDNA haplotype frequencies of bears from the southern Beaufort and Chukchi seas did not differ significantly. Lack of differentiation at both maternally inherited mtDNA and bi-parentally inherited microsatellite loci suggests that gene flow between the two areas is mediated by both sexes. The genetic data indicate that polar bears in the southern Beaufort and Chukchi seas compose one interbreeding population. However, there is considerable fidelity to ranges in each area, particularly by adult females. The combined genetic and movement data suggest that polar bears could be managed as Beaufort Sea and Chukchi Sea subpopulations of a combined southern Beaufort Sea and Chukchi Sea population. ?? 2006 NRC.

  4. Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice.

    PubMed

    Regehr, Eric V; Hunter, Christine M; Caswell, Hal; Amstrup, Steven C; Stirling, Ian

    2010-01-01

    1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for polar bears in the southern Beaufort Sea. Although sea ice declines in this and other regions of the polar basin have been among the greatest in the Arctic, to date population-level effects of sea ice loss on polar bears have only been identified in western Hudson Bay, near the southern limit of the species' range. 3. We estimated vital rates using multistate capture-recapture models that classified individuals by sex, age and reproductive category. We used multimodel inference to evaluate a range of statistical models, all of which were structurally based on the polar bear life cycle. We estimated parameters by model averaging, and developed a parametric bootstrap procedure to quantify parameter uncertainty. 4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001-2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0.96-0.99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0.73-0.79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide. 5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings therefore are

  5. Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice

    USGS Publications Warehouse

    Regehr, E.V.; Hunter, C.M.; Caswell, H.; Amstrup, Steven C.; Stirling, I.

    2010-01-01

    1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for polar bears in the southern Beaufort Sea. Although sea ice declines in this and other regions of the polar basin have been among the greatest in the Arctic, to date population-level effects of sea ice loss on polar bears have only been identified in western Hudson Bay, near the southern limit of the species' range. 3. We estimated vital rates using multistate capture-recapture models that classified individuals by sex, age and reproductive category. We used multimodel inference to evaluate a range of statistical models, all of which were structurally based on the polar bear life cycle. We estimated parameters by model averaging, and developed a parametric bootstrap procedure to quantify parameter uncertainty. 4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001-2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0 ∙ 96-0 ∙ 99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0 ∙ 73-0 ∙ 79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide. 5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings

  6. Geologic framework, petroleum potential, and environmental geology of the United States Beaufort and northeasternmost Chukchi Seas

    SciTech Connect

    Grantz, A.; May, S.D.; Dinter, D.A.

    1989-01-01

    The Beaufort and northeasternmost Chukchi Seas offer petroleum explorationists a promising terrane for medium to giant oil and gas accumulations, but the area is the most environmentally difficult region for petroleum exploration and development in the Nation. The region lies adjacent to the North Slope of Alaska, which is served by the Trans-Alaska Pipeline System (TAPS), a common carrier that would provide an outlet for oil brought to its northern terminus near Prudhoe Bay. If the proposed Alaska Natural Gas Transportation System is also built, its pipeline and terminus near Prudhoe Bay would provide the means for carrying offshore natural gas to market. The feasibility of economically transporting large volumes of oil or gas by tanker year-round from the Beaufort Sea to markets in the conterminous United States has yet to be demonstrated. This chapter gives an overview of the geologic framework, petroleum potential, and environmental geology of the Alaskan Beaufort and northeasternmost Chukchi Seas. The principal data base consists of the multichannel seismic-reflection profiles and accompanying high-resolution profiles shown in figure 11.1 and some additional single-channel seismic-reflection profiles, sonobuoy refraction measurements, seabed samples, and bathymetric data. The study area includes the entire Outer Continental Shelf (OCS) in the Alaskan Beaufort Sea and most of the OCS in the northeastern Chukchi Sea. Most of the continental shelf north of Alaska consists of areas shallower than 60 m (200 ft), where the national petroleum Council considers that the petroleum industry can now confidently proceed with operations. Sea-ice conditions in this area during late September, the usual period of maximum retreat, are shown. The base maps in this report use the conformal polar stereographic projection.

  7. Seasonal Ice loss in the Beaufort Sea: Toward Synchronicity and Prediction

    NASA Astrophysics Data System (ADS)

    Steele, M.; Dickinson, S.; Zhang, J.; Lindsay, R. W.

    2014-12-01

    The seasonal evolution of sea ice loss in the Beaufort Sea during 1979-2012 is examined, focusing on spatial differences between eastern and western sectors. Two stages in ice loss are identified: "opening" is defined as the spring decrease in ice concentration from its winter maximum below a value of 80% areal concentration; "retreat" is the summer decrease below 15% concentration. We consider three aspects of the problem, i.e. (i) the long-term mean, (ii) long-term linear trends, and (iii) year-to-year variability. We find that in the mean, ice opening occurs earliest in the southeast Beaufort Sea (SEB), forced by atmospheric heating acting on particularly thin ice relative to the southwestern Beaufort Sea (SWB). This thin SEB ice arises from divergence forced by easterly winds in fall and spring. There is no significant long-term trend in the date of SEB ice opening, although ice opening in the SWB is in fact trending toward earlier dates. This means that spatial differences in opening dates across the Beaufort Sea have been shrinking over the past 33 years, i.e., these dates are becoming more synchronous, a situation which may impact human and marine mammal activity in the area. Synchronicity in ice retreat dates is also increasing, although with no statistical significance at this time. Finally, we find that in any given year, an increase in monthly mean easterly winds of ~ 1 m/s during spring is associated with earlier summer retreat of 9-15 days, offering predictive capability with 1-2 months lead time.

  8. Waves in the Beaufort Sea Miz: First Results from a 30 Wavebuoy Array

    NASA Astrophysics Data System (ADS)

    Doble, M. J.; Wadhams, P.; Wilkinson, J.

    2014-12-01

    We present preliminary results from this year's deployment of 30 wavebuoys into the Beaufort Sea drifting ice cover. The buoys were deployed in two phases, both as part of the Office of Naval Research Marginal Ice Zone Departmental Research Initiative. 20 buoys were deployed into the continuous pack ice using aircraft-staged camps from Banks Island in March/April 2014, and the remaining 10 buoys were deployed from the South Korean icebreaker Araon in August 2014. All buoys transmitted continous timeseries of heave, roll and tilt - sampled at 1Hz - over the Iridium satellite network, along with their GPS positions. The goal is to examine the attenuation of storm-driven ocean waves as they enter and fracture the Beaufort Sea ice cover. These data are presented and the evolution of the directional wave field as it travels through the ice cover is examined.

  9. An Inverse Model of Double Diffusive Convection in the Beaufort Sea

    DTIC Science & Technology

    2009-12-01

    Master’s Thesis 4. TITLE AND SUBTITLE An Inverse Model of Double Diffusive Convection in the Beaufort Sea 6. AUTHOR(S) Jeremiah E. Chaplin 5 ...convection and mixing within the homogeneous layers............................... 5 Figure 4. Ice tethered profiler system....................14...Figure 5 . Location of ITP 1-6.............................15 Figure 6. Temperature – Salinity plot for ITPs 1-6........18 Figure 7. Histogram of data

  10. Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea

    USGS Publications Warehouse

    Amstrup, Steven C.; Stirling, I.; Smith, T.S.; Perham, C.; Thiemann, G.W.

    2006-01-01

    Intraspecific killing has been reported among polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus). Although cannibalism is one motivation for such killings, the ecological factors mediating such events are poorly understood. Between 24 January and 10 April 2004, we confirmed three instances of intraspecific predation and cannibalism in the Beaufort Sea. One of these, the first of this type ever reported for polar bears, was a parturient female killed at her maternal den. The predating bear was hunting in a known maternal denning area and apparently discovered the den by scent. A second predation event involved an adult female and cub recently emerged from their den, and the third involved a yearling male. During 24 years of research on polar bears in the southern Beaufort Sea region of northern Alaska and 34 years in northwestern Canada, we have not seen other incidents of polar bears stalking, killing, and eating other polar bears. We hypothesize that nutritional stresses related to the longer ice-free seasons that have occurred in the Beaufort Sea in recent years may have led to the cannibalism incidents we observed in 2004. ?? Springer-Verlag 2006.

  11. Submarine slope failures in the Beaufort Sea; Influence of gas hydrate decomposition

    NASA Astrophysics Data System (ADS)

    Grozic, J. L.; Dallimore, S.

    2012-12-01

    The continental shelf of the Beaufort Sea is composed of complex of marine and non-marine sequences of clay, silt, and sand. In many areas of the shelf these sediments contain occurrences of ice-bonded permafrost and associated pressure and temperature conditions that are conducive to the occurrence of methane gas hydrates. This complex environment is undergoing dramatic warming, where changes in sea level, ocean bottom temperatures, and geothermal regimes are inducing permafrost thawing and gas hydrate decomposition. Decomposition is inferred to be occurring at the base and top of the gas hydrate stability zone, which will cause sediment weakening and the generation of excess water and free gas. In such settings, the overlying permafrost cap may act as a permeability barrier, which could result in significant excess pore pressures and reduction in sediment stability. The shelf to slope transition is thought to be an area of extensive regional instability with acoustic records indicating there is upwards of 500 km of slumps and glides extending over the entire Beaufort margin. Some of these slide regions are coincident with up-dip limit of the permafrost gas hydrate stability zone. In this paper, a two dimensional model of the Beaufort shelf was constructed to examine the influence of gas hydrate decomposition on slope stability. The model relies on available data on the Beaufort sediments generated from offshore hydrocarbon exploration in the 1980s and 90s, as well as knowledge available from multidisciplinary marine research programs conducted in the outer shelf area. The slope stability model investigates the influence of marine transgression and ocean bottom warming by coupling soil deformation with hydrate dissociation during undrained conditions. By combining mechanical and thermal loading of the sediment, a more accurate indication of slope stability was obtained. The stability analysis results indicate a relatively low factor of safety for the Beaufort

  12. Sea ice circulation around the Beaufort Gyre: The changing role of wind forcing and the sea ice state

    NASA Astrophysics Data System (ADS)

    Petty, Alek A.; Hutchings, Jennifer K.; Richter-Menge, Jacqueline A.; Tschudi, Mark A.

    2016-05-01

    Sea ice drift estimates from feature tracking of satellite passive microwave data are used to investigate seasonal trends and variability in the ice circulation around the Beaufort Gyre, over the multidecadal period 1980-2013. Our results suggest an amplified response of the Beaufort Gyre ice circulation to wind forcing, especially during the late 2000s. We find increasing anticyclonic ice drift across all seasons, with the strongest trend in autumn, associated with increased ice export out of the southern Beaufort Sea (into the Chukchi Sea). A flux gate analysis highlights consistency across a suite of drift products. Despite these seasonal anticyclonic ice drift trends, a significant anticyclonic wind trend occurs in summer only, driven, in-part, by anomalously anticyclonic winds in 2007. Across all seasons, the ice drift curl is more anticyclonic than predicted from a linear relationship to the wind curl in the 2000s, compared to the 1980s/1990s. The strength of this anticyclonic ice drift curl amplification is strongest in autumn and appears to have increased since the 1980s (up to 2010). In spring and summer, the ice drift curl amplification occurs mainly between 2007 and 2010. These results suggest nonlinear ice interaction feedbacks (e.g., a weaker, more mobile sea ice pack), enhanced atmospheric drag, and/or an increased role of the ocean. The results also show a weakening of the anticyclonic wind and ice circulation since 2010.

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

    NASA Astrophysics Data System (ADS)

    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

  14. Distribution of dissolved organic matter in the eastern Bering Sea, Chukchi Sea (Barrow Canyon) and Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Shin, Kyung-Hoon; Tanaka, Noriyuki

    2004-12-01

    The distribution of dissolved organic carbon (DOC) in the western Arctic Ocean is greatly influenced by conservative riverine DOC flux into the northern Bering Sea, Bering Strait and Beaufort Sea, as indicated by an inverse correlation with salinity. Based on the relations between DOC, salinity and seawater temperature, several water masses could be identified. These included riverine water, ice-melt water, surface mixed water, cold and saline shelf water, and Atlantic Ocean water. High concentrations of chlorophyll a and DOC were found in some parcels of dense shelf water in Barrow Canyon. In addition, labile DOC compounds, such as polyunsaturated fatty acids (PUFA), were found in the dense shelf water, suggesting the dense shelf water contains a product (marine organic matter) of the biological CO2 pump.

  15. Interannual Variability and Long-Term Changes of Atmospheric Circulationover the Chukchi-Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Wu, Qigang; Zhang, Jing; Zhang, Xiangdong

    2013-04-01

    Recent studies have documented many features of the Beaufort Sea High (BSH), including seasonal cycle, temporal variability based on a BSH strength index, and a trend towards a stronger summer BSH that began in the late 1990s. In this study, we will further examine the variability and long-term trends of atmospheric circulation over the Chukchi-Beaufort Seas and northern Alaska using ERA Interim Reanalysis for the period of 1979-2012. To capture the moving feature of the BSH, the EOF analysis is applied to sea level pressure (SLP) field in the Chukchi-Beaufort Seas to investigate the principal patterns of the BSH variability for seasons of springtime (Apr.-May), summertime (Jun.-Aug.), autumn (Sep.-Oct.), and wintertime (Nov.-Mar.). In each season, the leading three EOF modes explain near 90% of the total variance, reflect a wintertime-like strengthened or weakened BSH centered over the western Arctic Ocean (EOF1), north-south dipole-like SLP anomalies (EOF2), and west-east dipole-like SLP anomalies (EOF3) respectively. The correlations are -0.83 between the PC time series of EOF1 (PC1) and the index of the Northern Annular Mode (NAM) in JJA, and -0.88 (0.57) between the PC 1 (PC2) of the EOF1 (EOF2) and the index of the North Pacific Oscillation (Pacific-North American) teleconnection pattern during Nov.-Mar., indicating that there are extensive controls of the BSH by the large-scale climate modes. Both PC2 associated with EOF2 in JJA and SO have exhibited a significant tendency toward high index polarity at the 10% level over the past few decades, are related to strongly reduced Arctic sea ice extent in summer and autumn. In the study period, we also detected significant anticyclonic trends of surface wind fields associated with a strengthened BSH during summer (JJA) and autumn (SO), and significant cyclonic trends of surface wind fields associated with a weakened BSH during early-middle winter (November to January). Such changes in atmospheric circulation from

  16. A year in the acoustic world of bowhead whales in the Bering, Chukchi and Beaufort seas

    NASA Astrophysics Data System (ADS)

    Clark, Christopher W.; Berchok, Catherine L.; Blackwell, Susanna B.; Hannay, David E.; Jones, Josh; Ponirakis, Dimitri; Stafford, Kathleen M.

    2015-08-01

    Bowhead whales, Balaena mysticetus, in the Bering-Chukchi-Beaufort (BCB) population, experience a variable acoustic environment among the regions they inhabit throughout the year. A total of 41,698 h of acoustic data were recorded from 1 August 2009 through 4 October 2010 at 20 sites spread along a 2300 km transect from the Bering Sea to the southeast Beaufort Sea. These data represent the combined output from six research teams using four recorder types. Recorders sampled areas in which bowheads occur and in which there are natural and anthropogenic sources producing varying amounts of underwater noise. We describe and quantify the occurrence of bowheads throughout their range in the Bering, Chukchi, and Beaufort seas over a 14-month period by aggregating our acoustic detections of bowhead whale sounds. We also describe the spatial-temporal variability in the bowhead acoustic environment using sound level measurements within a frequency band in which their sounds occur, by dividing a year into three, 4-month seasons (Summer-Fall 2009, August-November 2009: Winter 2009-2010, December 2009-March 2010: and Spring-Summer 2010, April-July 2010) and their home range into five zones. Statistical analyses revealed no significant relationship between acoustic occurrence, distance offshore, and water depth during Summer-Fall 2009, but there was a significant relationship during Spring-Summer 2010. A continuous period with elevated broadband sound levels lasting ca. 38 days occurred in the Bering Sea during the Winter 2009-2010 season as a result of singing bowheads, while a second period of elevated levels lasting at least 30 days occurred during the early spring-summer season as a result of singing bearded seals. The lowest noise levels occurred in the Chukchi Sea from the latter part of November into May. In late summer 2009 very faint sounds from a seismic airgun survey approximately 700 km away in the eastern Beaufort Sea were detected on Chukchi recorders. Throughout

  17. Arctic continental shelf morphology related to sea-ice zonation, Beaufort Sea, Alaska

    USGS Publications Warehouse

    Reimnitz, E.; Toimil, L.; Barnes, P.

    1978-01-01

    Landsat-1 and NOAA satellite imagery for the winter 1972-1973, and a variety of ice and sea-floor data were used to study sea-ice zonation and dynamics and their relation to bottom morphology and geology on the Beaufort Sea continental shelf of arctic Alaska. In early winter the location of the boundary between undeformed fast ice and westward-drifting pack ice of the Pacific Gyre is controlled by major coastal promontories. Pronounced linear pressure- and shear-ridges, as well as hummock fields, form along this boundary and are stabilized by grounding, generally between the 10- and 20-m isobaths. Slippage along this boundary occurs intermittently at or seaward of the grounded ridges, forming new grounded ridges in a widening zone, the stamukhi zone, which by late winter extends out to the 40-m isobath. Between intermittent events along the stamukhi zone, pack-ice drift and slippage is continuous along the shelf edge, at average rates of 3-10 km/day. Whether slippage occurs along the stamukhi zone or along the shelf edge, it is restricted to a zone several hundred meters wide, and ice seaward of the slip face moves at uniform rates without discernible drag effects. A causal relationship is seen between the spatial distribution of major ice-ridge systems and offshore shoals downdrift of major coastal promontories. The shoals appear to have migrated shoreward under the influence of ice up to 400 m in the last 25 years. The sea floor seaward of these shoals within the stamukhi zone shows high ice-gouge density, large incision depths, and a high degree of disruption of internal sedimentary structures. The concentration of large ice ridges and our sea floor data in the stamukhi zone indicate that much of the available marine energy is expended here, while the inner shelf and coast, where the relatively undeformed fast ice grows, are sheltered. There is evidence that anomalies in the overall arctic shelf profile are related to sea-ice zonation, ice dynamics, and bottom

  18. Variation in winter diet of southern Beaufort Sea polar bears inferred from stable isotope analysis

    USGS Publications Warehouse

    Bentzen, T.W.; Follmann, E.H.; Amstrup, Steven C.; York, G.S.; Wooller, M.J.; O'Hara, T. M.

    2007-01-01

    Ringed seals (Phoca hispida Schreber, 1775 = Pusa hispida (Schreber, 1775)) and bearded seals (Erignathus barbatus (Erxleben, 1777)) represent the majority of the polar bear (Ursus maritimus Phipps, 1774) annual diet. However, remains of lower trophic level bowhead whales (Balaena mysticetus L., 1758) are available in the southern Beaufort Sea and their dietary contribution to polar bears has been unknown. We used stable isotope (13C/12C, δ13C, 15N/14N, and δ15N) analysis to determine the diet composition of polar bears sampled along Alaska’s Beaufort Sea coast in March and April 2003 and 2004. The mean δ15N values of polar bear blood cells were 19.5‰ (SD = 0.7‰) in 2003 and 19.9‰ (SD = 0.7‰) in 2004. Mixing models indicated bowhead whales composed 11%–26% (95% CI) of the diets of sampled polar bears in 2003, and 0%–14% (95% CI) in 2004. This suggests significant variability in the proportion of lower trophic level prey in polar bear diets among individuals and between years. Polar bears depend on sea ice for hunting seals, and the temporal and spatial availabilities of sea ice are projected to decline. Consumption of low trophic level foods documented here suggests bears may increasingly scavenge such foods in the future.

  19. Phytoplankton in the Beaufort and Chukchi Seas: Distributions, Dynamics and Environmental Forcing

    NASA Technical Reports Server (NTRS)

    Wang, Jian; Cota, Glenn F.; Comiso, Josefino C.

    2005-01-01

    Time-series of remotely sensed distributions of phytoplankton, sea ice, surface temperature, albedo, and clouds were examined to evaluate the impact of the variability of environmental conditions and physical forcing on the phytoplankton distribution in the Beaufort and Chukchi Seas. Large-scale distributions of these parameters were studied for the first time using weekly and monthly composites from April 1998 through September 2002. The basic data set used in this study are phytoplankton pigment concentration derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), ice concentration obtained from the Special Sensor Microwave Imager (SSM/I) and surface temperature, cloud cover, and albedo derived from the Advanced Very High Resolution Radiometer (AVHRR). Seasonal variations of the sea ice cover was observed to be the dominant environmental factor as the ice edge blooms followed the retreating marginal ice zones northward. Blooms were most prominent in the southwestern Chukchi Sea, and were especially persistent immediately north of the Bering Strait in nutrient- rich Anadyr water and in some fronts. Chlorophyll concentrations are shown to increase from a nominal value during onset of melt in April to a maximum value in mid-spring or summer depending on location. Large interannual variability of ice cover and phytoplankton distributions was observed with the year 1998 being uniquely associated with an early season occurrence of a massive bloom. This is postulated to be caused in part by a rapid response of phytoplankton to an early retreat of the sea ice cover in the Beaufort Sea region. Correlation analyses showed relatively high negative correlation between chlorophyll and ice concentration with the correlation being highest in May, the correlation coefficient being -0.45. 1998 was also the warmest among the five years globally and the sea ice cover was least extensive in the Beaufort-Khukchi Sea region, partly because of the 1997-98 El Nino. Strong

  20. Seasonal variation of upwelling in the Alaskan Beaufort Sea: Impact of sea ice cover

    NASA Astrophysics Data System (ADS)

    Schulze, Lena M.; Pickart, Robert S.

    2012-06-01

    Data from a mooring array deployed from August 2002 to September 2004 are used to characterize differences in upwelling near the shelf break in the Alaskan Beaufort Sea due to varying sea ice conditions. The record is divided into three ice seasons: open water, partial ice, and full ice. The basic response is the same in each of the seasons. Roughly 8 h after the onset of easterly winds the shelf break jet reverses, followed approximately 10 h later by upwelling of saltier water which is cold near the shelf break (Pacific Winter Water) and warm at depth (Atlantic Water). The secondary circulation at the outer shelf is, to first order, consistent with a two-dimensional Ekman balance of offshore flow in the upper layer and onshore flow at depth. There are, however, important seasonal differences in the upwelling. Overall the response is strongest in the partial ice season and weakest in the full ice season. It is believed that these differences are dictated by the degree to which wind stress is transmitted through the pack-ice, as the strength of the wind-forcing was comparable over the three seasons. An EOF-based upwelling index is constructed using information about the primary flow, secondary flow, and hydrography. The ability to predict upwelling using the wind record alone is explored, which demonstrates that 90% of easterly wind events exceeding 9.5 m s-1 drive significant upwelling. During certain periods the ice cover on the shelf became landfast, which altered the upwelling and circulation patterns near the shelf break.

  1. Apparent optical properties of the Canadian Beaufort Sea - Part 1: Observational overview and water column relationships

    NASA Astrophysics Data System (ADS)

    Antoine, D.; Hooker, S. B.; Bélanger, S.; Matsuoka, A.; Babin, M.

    2013-07-01

    A data set of radiometric measurements collected in the Beaufort Sea (Canadian Arctic) in August 2009 (Malina project) is analyzed in order to describe apparent optical properties (AOPs) in this sea, which has been subject to dramatic environmental changes for several decades. The two properties derived from the measurements are the spectral diffuse attenuation coefficient for downward irradiance, Kd, and the spectral remote sensing reflectance, Rrs. The former controls light propagation in the upper water column. The latter determines how light is backscattered out of the water and becomes eventually observable from a satellite ocean color sensor. The data set includes offshore clear waters of the Beaufort Basin as well as highly turbid waters of the Mackenzie River plumes. In the clear waters, we show Kd values that are much larger in the ultraviolet and blue parts of the spectrum than what could be anticipated considering the chlorophyll concentration. A larger contribution of absorption by colored dissolved organic matter (CDOM) is responsible for these high Kd values, as compared to other oligotrophic areas. In turbid waters, attenuation reaches extremely high values, driven by high loads of particulate materials and also by a large CDOM content. In these two extreme types of waters, current satellite chlorophyll algorithms fail. This questions the role of ocean color remote sensing in the Arctic when Rrs from only the blue and green bands are used. Therefore, other parts of the spectrum (e.g., the red) should be explored if one aims at quantifying interannual changes in chlorophyll in the Arctic from space. The very peculiar AOPs in the Beaufort Sea also advocate for developing specific light propagation models when attempting to predict light availability for photosynthesis at depth.

  2. Apparent optical properties of the Canadian Beaufort Sea - Part 1: Observational overview and water column relationships

    NASA Astrophysics Data System (ADS)

    Antoine, D.; Hooker, S. B.; Belanger, S.; Matsuoka, A.; Babin, M.

    2013-03-01

    A data set of radiometric measurements collected in the Beaufort Sea (Canadian Arctic) in August 2009 (MALINA project) is analysed in order to describe apparent optical properties (AOPs) in this sea, which is subject to dramatic environmental changes for several decades. The two properties derived from the measurements are the spectral diffuse attenuation coefficient for downward irradiance, Kd, and the spectral remote sensing reflectance, Rrs. The former controls light propagation in the upper water column. The latter determines how light is backscattered out of the water and becomes eventually observable from a satellite ocean colour sensor. The data set includes offshore clear waters of the Beaufort basin as well as highly turbid waters of the Mackenzie River plumes. In the clear waters, we show Kd values that are much larger in the ultraviolet and blue parts of the spectrum than what could be anticipated considering the chlorophyll concentration. A larger contribution of absorption by coloured dissolved organic matter (CDOM) is responsible for this high Kd values, as compared to other oligotrophic areas. In turbid waters, attenuation reaches extremely high values, driven by high loads of particulate materials and also by a large CDOM content. In these two extreme types of waters, current satellite chlorophyll algorithms fail. This is questioning the role of ocean colour remote sensing in the Arctic when Rrs from only the blue and green bands are used. Therefore, other parts of the spectrum (e.g. the red) should be explored if one aims at quantifying interannual changes in chlorophyll in the Arctic from space. The very peculiar AOPs in the Beaufort Sea also advocate for developing specific light propagation models when attempting to predict light availability for photosynthesis at depth.

  3. Beaufort Sea Coastal Fish Studies Overview and Bibliography

    DTIC Science & Technology

    1993-06-01

    BiologicalJournaloftheLinnean Society, 38(3): gonins. Environmental Biology of Fishes, 5(1): 59-66. 281-301. Rogers, D.E. (1972) Wood River sockeye salmon stud- Skulason, S...formes locales de ]a truite Salvelius alpinus, of the Wood River Lakes, Bristol Bay , rouge du Quebec (Salvelinus marstoni). Nature Canada, Alaska...of the Alaskan Beauf rt development of the Prudhoe Bay oil fields continues to Sea is dominated by the Mackenzie River, to th.e east of have potential

  4. Arctic Oil Spill Response Guide for the Alaskan Beaufort Sea

    DTIC Science & Technology

    1988-03-01

    effective for subsea blowouts. Although the gas released by subsea blowouts will burn once it reaches the atmosphere, emulsification and thin oil...velocity of booms. OPTIMUM APPLICATION In light to heavy oils (excluding non- flowing products); in calm to moderate sea conditions; in thicknesses of...Encountered was 89%, Oil Content was 26% and Oil Recovery Rate was 7.6 m3 /h measured at separator flow rates of 11.9, 36.4 and 19.8 m 3 /h, respectively

  5. Beluga whale (Delphinapterus leucas) vocalizations and call classification from the eastern Beaufort Sea population.

    PubMed

    Garland, Ellen C; Castellote, Manuel; Berchok, Catherine L

    2015-06-01

    Beluga whales, Delphinapterus leucas, have a graded call system; call types exist on a continuum making classification challenging. A description of vocalizations from the eastern Beaufort Sea beluga population during its spring migration are presented here, using both a non-parametric classification tree analysis (CART), and a Random Forest analysis. Twelve frequency and duration measurements were made on 1019 calls recorded over 14 days off Icy Cape, Alaska, resulting in 34 identifiable call types with 83% agreement in classification for both CART and Random Forest analyses. This high level of agreement in classification, with an initial subjective classification of calls into 36 categories, demonstrates that the methods applied here provide a quantitative analysis of a graded call dataset. Further, as calls cannot be attributed to individuals using single sensor passive acoustic monitoring efforts, these methods provide a comprehensive analysis of data where the influence of pseudo-replication of calls from individuals is unknown. This study is the first to describe the vocal repertoire of a beluga population using a robust and repeatable methodology. A baseline eastern Beaufort Sea beluga population repertoire is presented here, against which the call repertoire of other seasonally sympatric Alaskan beluga populations can be compared.

  6. Organohalogen concentrations in blood and adipose tissue of Southern Beaufort Sea polar bears

    USGS Publications Warehouse

    Bentzen, T.W.; Muir, D.C.G.; Amstrup, Steven C.; O'Hara, T. M.

    2008-01-01

    We analyzed 151 organohalogen chemicals (OHCs) in whole blood and subcutaneous fat of 57 polar bears sampled along the Alaskan Beaufort Sea coast in spring, 2003. All major organochlorine pesticides, PCBs, PBDEs and their congeners were assessed. Concentrations of most OHCs continue to be lower among Southern Beaufort Sea polar bears than reported for other populations. Additionally, toxaphenes and related compounds were assessed in adipose tissue, and 8 perflourinated compounds (PFCs) were examined in blood. Perfluorooctane sulfonate (PFOS) concentrations exceeded those of any other contaminant measured in blood. ??Chlordane concentrations were higher in females, and both ??PCBs and ??Chlordane concentrations in adipose tissue decreased significantly with age. The rank order of OHC mean concentrations; ??PCB > ??10PCB > PCB153 > ??Chlordane > Oxychlordane > PCB180 > ??HCH > ??-HCH > ??DDT > p,p-DDE > ??PBDE > HCB > Toxaphene was similar for compounds above detection limits in both fat and blood. Although correlation between OHC concentrations in blood and adipose tissue was examined, the predictability of concentrations in one matrix for the other was limited. ?? 2008 Elsevier B.V.

  7. Dynamics and morphology of Beaufort Sea ice determined from satellites, aircraft, and drifting stations

    NASA Technical Reports Server (NTRS)

    Campbell, W. J.; Gloersen, P.; Nordberg, W.; Wilheit, T. T.

    1973-01-01

    A series of measurements from drifting stations, aircraft, the ERTS-1, Nimbus 4, and Nimbus 5 satellites have jointly provided a new description of the dynamics and morphology of the ice cover of the Beaufort Sea. The combined analysis of these data show that the eastern Beaufort Sea ice cover is made up of large multiyear floes while the western part is made of small, predominantly first-year floes. The analysis suggests that this distribution might be quasi-steady and that the dynamics and thermodynamics of the region are more complex than hitherto known. The measurements consist of: (1) high resolution ERTS-1 imagery which is used to describe floe size and shape distribution, short term floe dynamics, and lead and polynya dynamics; (2) tracking by Nimbus 4 of IRLS drifting buoys to provide ice drift information which enhances the interpretation of the ERTS-1 imagery; (3) Nimbus 5 microwave (1.55 cm wavelength) imagery which provides synoptic, sequential maps on the distribution of multiyear and first-year ice types; (4) airborne microwave surveys and surface based observations made during 1971 and 1972 in conjunction with the AIDJEX (Arctic Ice Dynamics Joint Experiment) program.

  8. Ice gouge obliteration and sediment redistribution event: 1977-1978, Beaufort Sea, Alaska

    USGS Publications Warehouse

    Barnes, Peter W.; Reimnitz, Erk

    1979-01-01

    In 1978 major changes in shelf morphology were observed during a routine re-survey of part of the inner shelf region of the central Beaufort Sea. Regional observations are coupled with a detailed diving and side-scan study of a single ice gouge of known age to develop a detailed description of the altered seabed conditions. Hydrodynamic activity has caused extensive sediment reworking, obliterating ice gouges to water depths of at least 13 m and has caused ponding of sediment in ice gouge terrain in deeper waters. Ponded sediment is characterized as a soft, sometimes very poorly consolidated, mud unit underlain by a stiffer, more consolidated, silty clay. In places, stiff silty clay is exposed in windows in the sediment pond and displays a fine-textured ice gouge morphology. Rates of sediment reworking and redisposition from apparently episodic events are an order of magnitude greater than the average sediment accumulation rates on the Beaufort Sea shelf. Reported maximum ice gouge incision depths are not representative of maximum ice keel penetrations into the seabed because these sedimentation events preferentially infill gouges. Furthermore, because these sedimentation events concentrate sediments in gouge troughs, a series of overlapping and interfingering 'shoestring' deposits is developed which should characterize the ice gouge stratigraphy. The specific hydraulic mechanisms for sediment redistribution and sediment compaction observed in this study are only poorly understood.

  9. Behavior, disturbance responses, and distribution of bowhead whales Balaena mysticetus in the eastern Beaufort Sea. 1980-84. Final report

    SciTech Connect

    Richardson, W.J.

    1985-06-01

    The reactions of bowhead whales to industrial activities were studied during five summers in the report. The objective was to provide data needed to assess the possible effects of offshore oil exploration and development in the Alaskan Beaufort Sea on this endangered species.

  10. Organic geochemical signatures controlling methane outgassing at active mud volcanoes in the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    DongHun, Lee; YoungKeun, Jin; JungHyun, Kim; Heldge, Niemann; JongKu, Gal; BoHyung, Choi

    2016-04-01

    Based on the water column acoustic anomalies related to active methane (CH4) venting, numerous active Mud Volcanoes (MVs) were recently identified at ~282, ~420, and ~740 m water depths on the continental slope of the Canadian Beaufort Sea (Paull et al., 2015). While geophysical aspects such as the multibeam bathymetric mapping are thoroughly investigated, biogeochemical processes controlling outgassing CH4 at the active MVs are not well constrained. Here, we investigated three sediment cores from the active MVs and one sediment core from a non-methane influenced reference site recovered during the ARA-05C expedition with the R/V ARAON in 2014. We analyzed lipid biomarkers and their stable carbon isotopic values (δ13C) in order to determine key biogeochemical processes involved in CH4 cycling in the MV sediments. Downcore CH4 and sulphate (SO42-) concentration measurements revealed a distinct sulfate-methane transition zone (SMTZ) at the shallow sections of the cores (15 - 45 cm below seafloor (cm bsf) at 282 m MV, 420 m MV, and 740 m MV). The most abundant diagnostic lipid biomarkers in the SMTZ were sn-2-hydroxyarchaeol (-94‰) and archaeol (-66‰) with the sn-2-hydroxyarchaeol: archaeol ratio of 1.1 to 5, indicating the presence of ANME-2 or -3. However, we also found substantial amounts of monocyclic biphytane-1 (BP-1, -118‰), which is rather indicative for ANME-1. Nevertheless, the concentration of sn-2-hydroxyarchaeol was 2-fold higher than any other archaeal lipids, suggesting a predominant ANME-2 or -3 rather than ANME-1 as a driving force for the anaerobic methane oxidation (AOM) in these systems. We will further investigate the microbial community at the active MVs using nucleic acid (RNA and DNA) sequence analyses in near future. Our study provides first biogeochemical data set of the active MVs in the Canadian Beaufort Sea, which helps to better understand CH4 cycling mediated in these systems. Reference Paull, C.K., et al. (2015), Active mud

  11. Arctic underwater noise transients from sea ice deformation: Characteristics, annual time series, and forcing in Beaufort Sea.

    PubMed

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

    2015-10-01

    A 13-month time series of Arctic Ocean noise from the marginal ice zone of the Eastern Beaufort Sea is analyzed to detect under-ice acoustic transients isolated from ambient noise with a dedicated algorithm. Noise transients due to ice cracking, fracturing, shearing, and ridging are sorted out into three categories: broadband impulses, frequency modulated (FM) tones, and high-frequency broadband noise. Their temporal and acoustic characteristics over the 8-month ice covered period, from November 2005 to mid-June 2006, are presented and their generation mechanisms are discussed. Correlations analyses showed that the occurrence of these ice transients responded to large-scale ice motion and deformation rates forced by meteorological events, often leading to opening of large-scale leads at main discontinuities in the ice cover. Such a sequence, resulting in the opening of a large lead, hundreds by tens of kilometers in size, along the margin of landfast ice and multiyear ice plume in the Beaufort-Chukchi seas is detailed. These ice transients largely contribute to the soundscape properties of the Arctic Ocean, for both its ambient and total noise components. Some FM tonal transients can be confounded with marine mammal songs, especially when they are repeated, with periods similar to wind generated waves.

  12. Bowhead whale behavior in relation to seismic exploration, Alaskan Beaufort Sea, Autumn 1981. Study report (Final)

    SciTech Connect

    Fraker, M.A.; Ljungblad, D.K.; Richardson, W.J.; Van Schoik, D.R.

    1985-10-01

    Behavior of bowhead whales (Balsena mysticetus) in the eastern part of the Alaskan Beaufort Sea or near the Alaska/Yukon border was observed from a circling turbine-powered Goose aircraft on 10 dates from 12 September to 5 October 1981. On three of these dates, the whales were exposed t, noise impulses from seismic vessels 13 km or more away. Some behavioral data were acquired. In both the presence and the absence of seismic impulses, most bowheads appeared to be feeding in the water column, although slow travel and active socializing were sometimes detected. Sonobuoys detected bowhead calls both in the presence and the absence of seismic impulses. There was no clear evidence of unusual behavior in the presence of seismic impulses.

  13. Polar bears in the Beaufort Sea: A 30-year mark-recapture case history

    USGS Publications Warehouse

    Amstrup, Steven C.; McDonald, T.L.; Stirling, I.

    2001-01-01

    Knowledge of population size and trend is necessary to manage anthropogenic risks to polar bears (Ursus maritimus). Despite capturing over 1,025 females between 1967 and 1998, previously calculated estimates of the size of the southern Beaufort Sea (SBS) population have been unreliable. We improved estimates of numbers of polar bears by modeling heterogeneity in capture probability with covariates. Important covariates referred to the year of the study, age of the bear, capture effort, and geographic location. Our choice of best approximating model was based on the inverse relationship between variance in parameter estimates and likelihood of the fit and suggested a growth from ≈ 500 to over 1,000 females during this study. The mean coefficient of variation on estimates for the last decade of the study was 0.16—the smallest yet derived. A similar model selection approach is recommended for other projects where a best model is not identified by likelihood criteria alone.

  14. Active mud volcanoes on the continental slope of the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Caress, D. W.; Gwiazda, R.; Melling, H.; Riedel, M.; Jin, Y. K.; Hong, J. K.; Kim, Y.-G.; Graves, D.; Sherman, A.; Lundsten, E.; Anderson, K.; Lundsten, L.; Villinger, H.; Kopf, A.; Johnson, S. B.; Hughes Clarke, J.; Blasco, S.; Conway, K.; Neelands, P.; Thomas, H.; Côté, M.

    2015-09-01

    Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.

  15. Long-Term Movement of Satellite-Tracked Buoys in the Beaufort Sea.

    DTIC Science & Technology

    1981-06-01

    REPORT 6. Pffor,,,qOrgen,e.en Code 8. Per/orm0nq Orgern0=° , 0o s Reo.r N. 7 . A tire s) D.L. MURPHY, P.A. TEBEAU, and I.M. LISSAUER CGR&DC 12/81 9 ...Cy NC 0,- X - 0--ece 0 o ~z w m > C Dh. > U) z, CL NII CD E E C Z2 0C ii Ca 0 C V c 0 1 E 06 .C- z 5 0 lea a O z B S& LL L C. CL zL L OL 9 a. 1 C(AII z...Small Buoy Hull Used in this Study 5 4 Release Site in the Southeastern Beaufort Sea 7 5 Tracks of Buoys Released on 9 August 1979 8 6 Tracks of Buoys

  16. Linking mercury exposure to habitat and feeding behaviour in Beaufort Sea beluga whales

    NASA Astrophysics Data System (ADS)

    Loseto, L. L.; Stern, G. A.; Deibel, D.; Connelly, T. L.; Prokopowicz, A.; Lean, D. R. S.; Fortier, L.; Ferguson, S. H.

    2008-12-01

    Mercury (Hg) levels in the Beaufort Sea beluga population have been increasing since the 1990's. Ultimately, it is the Hg content of prey that determines beluga Hg levels. However, the Beaufort Sea beluga diet is not understood, and little is known about the diet Hg sources in their summer habitat. During the summer, they segregate into social groups based on habitat use leading to the hypothesis that they may feed in different food webs explaining Hg dietary sources. Methyl mercury (MeHg) and total mercury (THg) levels were measured in the estuarine-shelf, Amundsen Gulf and epibenthic food webs in the western Canadian Arctic collected during the Canadian Arctic Shelf Exchange Study (CASES) to assess their dietary Hg contribution. To our knowledge, this is the first study to report MeHg levels in estuarine fish and epibenthic invertebrates from the Arctic Ocean. Although the Mackenzie River is a large source of Hg, the estuarine-shelf prey items had the lowest MeHg levels, ranging from 0.1 to 0.27 μg/g dry weight (dw) in arctic cisco ( Coregonus autumnalis) and saffron cod ( Eleginus gracilis) respectively. Highest MeHg levels occurred in fourhorn sculpin ( Myoxocephalus quadricornis) (0.5 μg/g dw) from the epibenthic food web. Beluga hypothesized to feed in the epibenthic and Amundsen Gulf food webs had the highest Hg levels matching with high Hg levels in associated food webs, and estuarine-shelf belugas had the lowest Hg levels (2.6 μg/g dw), corresponding with the low food web Hg levels, supporting the variation in dietary Hg uptake. The trophic level transfer of Hg was similar among the food webs, highlighting the importance of Hg sources at the bottom of the food web as well as food web length. We propose that future biomagnification studies incorporate predator behaviour with food web structure to assist in the evaluation of dietary Hg sources.

  17. Impact of data assimilation on Chukchi/Beaufort Seas mesoscale modeling

    NASA Astrophysics Data System (ADS)

    Liu, F.; Krieger, J.; Zhang, J.

    2010-12-01

    Offshore development in the Chukchi/Beaufort Seas requires an improved understanding of the surface wind field, a crucial parameter for assessing and predicting dispersal and movement of oil spills. A study has thus been established to investigate the mesoscale features of the surface wind field throughout this region. In this study, we focus on investigating the impact of data assimilation on the simulation of the Chukchi/Beaufort Seas mesoscale surface wind field with the Weather Research and Forecasting model (WRF) and its variational data assimilation system (WRF-Var). In the application of WRF-Var, model background error (BE) is a key element required for the assimilation procedure. We have conducted an investigation into how varying the model background error affects the results of assimilating in-situ surface observations. The background error covariances we tested include CV3 (a built-in global BE file in WRF-Var) and several domain-dependent CV5 BE files. The latter were calculated using 12-hourly forecast results and 24-hourly forecast over 2-month and 1-year periods, followed by the calculation of separate BE at 00, 06, 12, and 18 UTC, in order to capture the diurnal variation of the model background error. The results show that the customized domain-dependent BE produces much better assimilation results than the global CV3 BE, and the CV5 BE calculated over a 1-year period additionally helps to improve the assimilation. When the diurnal variation of background error was included in the CV5 BE, a further improvement was achieved.

  18. Stock origins of Dolly Varden collected from Beaufort Sea coastal sites of Arctic Alaska and Canada

    USGS Publications Warehouse

    Krueger, C.C.; Wilmot, R.L.; Everett, R.J.

    1999-01-01

    Anadromous northern Dolly Varden Salvelinus malma support a summer subsistence fishery in Beaufort Sea coastal waters. These same waters coincide with areas of oil and gas exploration and development. The purpose of this study was to assess variation in stock origins of Dolly Varden collected from sites along 400 km of Beaufort Sea coast. Mixed-stock analyses (MSA) of allozyme data were used to compare collections from four sites (Endicolt near Prudhoe Bay, Mikkelsen Bay, and Kaktovik in Alaska and Phillips Bay in Canada) and to assess variation in stock contributions among summer months and between 1987 and 1988. The MSA estimates for individual stocks were summed into estimates for three stock groups: western stocks from the area near Sagavarnirktok River and Prudhoe Bay (SAG), Arctic National Wildlife Refuge stocks (Arctic Refuge), and Canadian stocks. The MSA of Endicott samples taken in 1987 and 1988 did not differ among months in terms of contributions from local SAG stocks (range, 71-95%). Contributions from nonlocal (>100 km distant) Canadian and Arctic Refuge stocks were not different from zero in 1987, but contributions from Canadian stocks were so in July (17%) and August (20%) but not in September of 1988. Thus, stock contributions to Endicott collections were different between 1987 and 1988. Samples from the Kaktovik area in 1988 were different between months in terms of contributions from nonlocal SAG stocks (July, 7%; August, 27%). Significant contributions to these samples were made both months by Canadian (25% and 17%) and local Arctic Refuge stocks (68% and 56%). Among the four coastal sites, local stocks typically contributed most to collections; however, every site had collections that contained significant contributions from nonlocal stocks. The MSA estimates clearly revealed the movement of Dolly Varden between U.S. and Canada coastal waters. If local stocks are affected by oil and gas development activities, distant subsistence fisheries

  19. Monitoring hydrocarbons and trace metals in Beaufort Sea sediments and organisms. Final report

    SciTech Connect

    Boehm, P.; LeBlanc, L.; Trefry, J.; Marajh-Whittemore, P.; Brown, J.

    1990-10-01

    As part of the Minerals Management Service's environmental studies of oil and gas exploration and production activities in the Alaskan Beaufort Sea, a study was conducted in 1989 to monitor the marine environment for inputs of chemicals related to drilling and exploration. The 1989 Beaufort Sea Monitoring Program (BSMP) was designed to monitor sediments and selected benthic organisms for trace metals and hydrocarbons so as to infer any changes that might have resulted from drilling and production activities. A series of 49 stations were sampled during the program. The study area extended from Cape Halkett on the western end of Harrison Bay to Griffin Point, east of Barter Island. The sampling design combined an area-wide approach in which stations were treated as replicates of 8 specific geographic regions, with an activity-specific approach, which focused on the potential establishment of metal or hydrocarbon concentration gradients with distance from the Endicott Production Field in Prudhoe Bay. The analytical program focused on the analysis of the fine-fraction of the sediment for a series of trace metals and elements and the analysis of a suite of saturated and aromatic hydrocarbons in the bulk sediment. The total organic carbon (TOB) content and the grain size distribution in the sediments were determined as well. Benthic bivalve molluscs, representative of several feeding types were collected from those stations for which data previously existed from the 1984-1986 BSMP, and were analyzed for metals and saturated and aromatic hydrocarbons. The benthic amphipods were collected, pooled by station or region, and analyzed as well.

  20. Fall Freeze-up of Sea Ice in the Beaufort-Chukchi Seas Using ERS-1 SAR and Buoy Data

    NASA Technical Reports Server (NTRS)

    Holt, B.; Winebrenner, B.; D., Nelson E.

    1993-01-01

    The lowering of air temperatures below freezing in the fall indicates the end of summer melt and the onset of steady sea ice growth. The thickness and condition of ice that remains at the end of summer has ramifications for the thickness that that ice will attain at the end of the following winter. This period also designates a shifting of key fluxes from upper ocean freshening from ice melt to increased salinity from brine extraction during ice growth. This transitional period has been examined in the Beaufort and Chukchi Seas using ERS-1 SAR imagery and air temperatures from drifting buoys during 1991 and 1992. The SAR imagery is used to examine the condition and types of ice present in this period. Much of the surface melt water has drained off at this time. Air temperatures from drifting buoys coincident in time and within 100 km radius of the SAR imagery have been obtained...

  1. Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006

    USGS Publications Warehouse

    Stirling, I.; McDonald, T.L.; Richardson, E.S.; Regehr, E.V.; Amstrup, Steven C.

    2011-01-01

    Polar bears (Ursus maritimus) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open-population capture–recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highest-ranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2–4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 ± 155 (mean and 95% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (<300 m water depth) has declined over the 35-year period of this study. If the climate continues to warm as predicted, we predict that the polar bear population in the northern Beaufort Sea will eventually decline

  2. The ice fauna in the shallow southwestern Beaufort Sea, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Carey, Andrew G.

    1992-06-01

    Sympagic fauna were studied in seasonal fast ice adjacent to Narwhal Island during the spring of 1979 and 1980, with emphasis on the origin of the fauna and its relationship to contiguous pelagic and benthic communities. The results of five subprojects are reviewed and compared with recent literature. Within Stefansson Sound, inshore of Narwhal Island, total sympagic meiofaunal densities and species diversity were low. In March 1979, the dominant taxa were polychaete larvae and crustacean nauplii, while in May the dominant group was Nematoda. Total numerical densities were low, ranging from 4500 to 8000 per m 2. During the spring of 1980 large numbers of invertebrate fauna concentrated at the undersurface of seasonal sea ice on the inner western Beaufort Sea continental shelf, seaward of Narwhal Island. The sympagic meiofauna were comprised primarily of benthic harpacticoid and cyclopoid copepods, turbellarians, nematode worms, and polychaete worm larvae. Total meiofaunal densities increased from about 6000 per m 2 in April to about 482,000 per m 2 in June. All life stages of Cyclopina gracilis (Copepoda: Cyclopoida) were present in the ice. This species appeared to reproduce continuously from early April to early June during the study period. The Harpacticus sp. (Copepoda: Harpaticoida) population consisted of one cohort whose individuals grew in size from April to early June. The sympagic macrofauna consisted entirely of amphipod crustaceans, primarily comprised of benthic species. Population size structure of the amphipod Pseudalibrotus (= Onisimus) litoralis was bimodal and there was a lack of intermediate growth stages. These characteristics indicate that this species has a two-year life cycle in the Beaufort Sea. The highest growth rate for P. litoralis coincided with maximal ice algal production. P. litoralis fed largely on meiofaunal Crustacea and amphipod fragments in April, but its diet switched to ice algae during the height of the bloom in late May

  3. Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006.

    PubMed

    Stirling, Ian; McDonald, Trent L; Richardson, E S; Regehr, Eric V; Amstrup, Steven C

    2011-04-01

    Polar bears (Ursus maritimus) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open-population capture-recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highest-ranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2-4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 +/- 155 (mean and 95% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (< 300 m water depth) has declined over the 35-year period of this study. If the climate continues to warm as predicted, we predict that the polar bear population in the northern Beaufort Sea will eventually decline

  4. Alaskan Beaufort Sea Heat Flow and Ocean Temperature Analysis: Implications for Stability of Climate-Sensitive Continental Slope Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Phrampus, B. J.; Hornbach, M. J.; Ruppel, C. D.; Hart, P. E.

    2013-12-01

    Based on USGS estimates, gas hydrates beneath the continental slope of the US Beaufort Sea sequester several gigatons of methane. Warming of Beaufort Sea intermediate waters has the potential to cause dissociation of upper slope gas hydrates, release of methane to the overlying water column, and the buildup of pore pressure in slope sediments in an area first used by Kayen and Lee (1991) as the archetype for linked gas hydrate dynamics and slope failures. Limited constraints on regional heat flow, ocean temperature variability, and the extent of methane hydrates across the region have made analysis of Beaufort continental slope gas hydrate system difficult. Using legacy USGS seismic data combined with a new 3D thermal refraction model and more than 30 years of ocean temperature measurements, we analyze the stability of Beaufort continental slope methane hydrates. Our analysis provides the first regional heat flow map of the Alaskan shelf and margin, a detailed >30 year assessment of ocean temperature change in this region, and the first map revealing where disequilibrium methane hydrate stability conditions exist in the Western Beaufort Sea. Our results show that heat flow is complex and highly variable across the Beaufort margin, that intermediate ocean temperatures have warmed steadily for more than 30 years, and that the gas hydrates on the upper slope are out of equilibrium with overlying intermediate waters over large parts of the area. The discrepancy between observed and predicted hydrate stability depths is best explained by significant (>1 degC) intermediate ocean warming since the last glacial maximum. Even in the absence of persistent ocean warming conditions in the near future, the results predict destabilization of gas hydrates underlying an area ranging from ~4,750 km2 to ~30,000 km2 on the US Beaufort continental slope over the next 100 years. A fraction of the methane released by these gas hydrates may be emitted at seafloor seeps and contribute to

  5. The application of ERTS imagery to monitoring Arctic sea ice. [mapping ice in Bering Sea, Beaufort Sea, Canadian Archipelago, and Greenland Sea

    NASA Technical Reports Server (NTRS)

    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.

  6. Sea ice and the onshore offshore gradient in pre-winter zooplankton assemblages in southeastern Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Darnis, Gérald; Barber, David G.; Fortier, Louis

    2008-12-01

    Zooplankton communities were studied in southeastern Beaufort Sea (Arctic Ocean) in September-October 2002. Cluster analysis and non-metric multidimensional scaling revealed three distinct mesozooplankton assemblages. A neritic assemblage occurred on the Mackenzie Shelf and in Franklin Bay, while distinct off-shelf assemblages prevailed in the Cape Bathurst Polynya and on the Beaufort Slope respectively. Over 95% of the mesozooplankton was comprised of eight copepod taxa. Pseudocalanus spp. contributed predominantly to the discrimination of the three assemblages and was the only significant indicator of the Shelf assemblage. Oithona similis, Oncaea borealis, Metridia longa and Calanus hyperboreus were indicators of the Polynya assemblage. Cyclopina sp. and Microcalanus pygmaeus were indicative of the overall off-shelf community (Polynya and Slope assemblages). The importance of omnivores and carnivores increased from the shelf to the polynya and the slope. Station depth and duration of reduced ice conditions during summer (< 50% ice concentration) underpinned the distribution of the assemblages ( r2 = 0.71 and 0.45 respectively). The abundance of Pseudocalanus spp. was independent of depth and increased with the duration of reduced ice conditions ( rs = 0.438). The abundance of Cyclopina sp., M. pygmaeus and other indicators of the offshore assemblages followed the opposite trend ( rs = - 0.467 and - 0.5 respectively). Under continued climate warming, a reduction of the ice cover will affect the biogeography of mesozooplankton on and around the Mackenzie Shelf, to the potential advantage of Pseudocalanus spp. and other calanoid herbivores.

  7. Minimum distribution of subsea ice-bearing permafrost on the US Beaufort Sea continental shelf

    USGS Publications Warehouse

    Brothers, Laura L.; Hart, Patrick E.; Ruppel, Carolyn D.

    2012-01-01

    Starting in Late Pleistocene time (~19 ka), sea level rise inundated coastal zones worldwide. On some parts of the present-day circum-Arctic continental shelf, this led to flooding and thawing of formerly subaerial permafrost and probable dissociation of associated gas hydrates. Relict permafrost has never been systematically mapped along the 700-km-long U.S. Beaufort Sea continental shelf and is often assumed to extend to ~120 m water depth, the approximate amount of sea level rise since the Late Pleistocene. Here, 5,000 km of multichannel seismic (MCS) data acquired between 1977 and 1992 were examined for high-velocity (>2.3 km s−1) refractions consistent with ice-bearing, coarse-grained sediments. Permafrost refractions were identified along <5% of the tracklines at depths of ~5 to 470 m below the seafloor. The resulting map reveals the minimum extent of subsea ice-bearing permafrost, which does not extend seaward of 30 km offshore or beyond the 20 m isobath.

  8. Coastal retreat and shoreface profile variations in the Canadian Beaufort Sea

    USGS Publications Warehouse

    Hequette, A.; Barnes, P.W.

    1990-01-01

    The coastline of the southern Canadian Beaufort Sea consists primarily of unconsolidated bluffs. Although the sea is ice-free for 3 months of the year and wave energy is restricted by pack ice, the coast is undergoing regional retreat with erosion rates as high as 10 m a-1 in some locations. Simple and multiple regression analyses were carried out to determine the degree of correlation between the mean retreat rate measured at various locations and the different parameters that may control shoreline recession. Sediment texture, ground-ice content, cliff height, wave energy and shoreface gradient revealed medium to poor correlation with erosion rates, showing that the recessive evolution of the coastline can not be explained solely by wave-induced and subaerial processes. The comparison of nearshore echo-sounding records from 1987 with bathymetry from 1971 showed substantial erosion (up to 1 m) of the submarine profile between 12 and 15 m of water. There is strong evidence that this erosion has been caused by sea ice gouging on the seafloor. From depths of 5 to 9 m, accretion has taken place, possibly induced by ice-push processes, and inshore of the 5 m isobath wave and current erosion of the shoreface has occurred. These results suggest that the erosion of the inner shelf by ice gouging drives the erosion observed inshore on the coastal bluffs and nearshore zone as the shoreface profile strives for a state of dynamic equilibrium. ?? 1990.

  9. A new genus and species of Thyasiridae (Mollusca, Bivalvia) from deep-water, Beaufort Sea, northern Alaska

    PubMed Central

    Valentich-Scott, Paul; Powell, Charles L.; II; Lorenson, Thomas D.; Edwards, Brian E.

    2014-01-01

    Abstract Bivalve mollusk shells were collected in 2350 m depth in the Beaufort Sea, Arctic Ocean off northern Alaska. Initial identification suggested the specimens were a member of the bivalve family Thyasiridae, but no known eastern Pacific or Arctic living or fossil thyasirid resembled these deep-water specimens. Comparisons were made with the type of the genera Maorithyas Fleming, 1950, Spinaxinus Oliver & Holmes, 2006, Axinus Sowerby, 1821, and Parathyasira Iredale, 1930. We determined the Beaufort Sea species represents a new genus, herein described as Wallerconcha. These specimens also represent a new species, herein named Wallerconcha sarae. These new taxa are compared with known modern and fossil genera and species of thyasirds. PMID:25589851

  10. Upper Ocean Evolution Across the Beaufort Sea Marginal Ice Zone from Autonomous Gliders

    NASA Astrophysics Data System (ADS)

    Lee, Craig; Rainville, Luc; Perry, Mary Jane

    2016-04-01

    The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g., the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters), and elevated surface wave energy that acts to deform and fracture sea ice. Spatial and temporal variability in ice properties and open water fraction impact these processes. To investigate how upper ocean structure varies with changing ice cover, and how the balance of processes shift as a function of ice fraction and distance from open water, four long-endurance autonomous Seagliders occupied sections that extended from open water, through the marginal ice zone, deep into the pack during summer 2014 in the Beaufort Sea. Sections reveal strong fronts where cold, ice-covered waters meet waters that have been exposed to solar warming, and O(10 km) scale eddies near the ice edge. In the pack, Pacific Summer Water and a deep chlorophyll maximum form distinct layers at roughly 60 m and 80 m, respectively, which become increasingly diffuse as they progress through the MIZ and into open water. The isopynal layer between 1023 and 1024 kgm-3, just above the PSW, consistently thickens near the ice edge, likely due to mixing or energetic vertical exchange associated with strong lateral gradients in this region. This presentation will discuss the upper ocean variability, its relationship to sea ice extent, and evolution over the summer to the start of freeze up.

  11. Effects of capturing and collaring on polar bears: findings from long-term research on the southern Beaufort Sea population

    USGS Publications Warehouse

    Rode, Karyn D.; Pagano, Anthony M.; Bromaghin, Jeffrey F.; Atwood, Todd C.; Durner, George M.; Simac, Kristin; Amstrup, Steven C.

    2014-01-01

    Implications: This study provides empirical evidence that current capture-based research methods do not have long-term implications, and are not contributing to observed changes in body condition, reproduction or survival in the southern Beaufort Sea. Continued refinement of capture protocols, such as the use of low-impact dart rifles and reversible drug combinations, might improve polar bear response to capture and abate short-term reductions in activity and movement post-capture.

  12. Aerial Surveys of the Beaufort Sea Seasonal Ice Zone in 2012-2014

    NASA Astrophysics Data System (ADS)

    Dewey, S.; Morison, J.; Andersen, R.; Zhang, J.

    2014-12-01

    Seasonal Ice Zone Reconnaissance Surveys (SIZRS) of the Beaufort Sea aboard U.S. Coast Guard Arctic Domain Awareness flights were made monthly from May 2012 to October 2012, June 2013 to August 2013, and June 2014 to October 2014. In 2012 sea ice extent reached a record minimum and the SIZRS sampling ranged from complete ice cover to open water; in addition to its large spatial coverage, the SIZRS program extends temporal coverage of the seasonal ice zone (SIZ) beyond the traditional season for ship-based observations, and is a good set of measurements for model validation and climatological comparison. The SIZ, where ice melts and reforms annually, encompasses the marginal ice zone (MIZ). Thus SIZRS tracks interannual MIZ conditions, providing a regional context for smaller-scale MIZ processes. Observations with Air eXpendable CTDs (AXCTDs) reveal two near-surface warm layers: a locally-formed surface seasonal mixed layer and a layer of Pacific origin at 50-60m. Temperatures in the latter differ from the freezing point by up to 2°C more than climatologies. To distinguish vertical processes of mixed layer formation from Pacific advection, vertical heat and salt fluxes are quantified using a 1-D Price-Weller-Pinkel (PWP) model adapted for ice-covered seas. This PWP simulates mixing processes in the top 100m of the ocean. Surface forcing fluxes are taken from the Marginal Ice Zone Modeling and Assimilation System MIZMAS. Comparison of SIZRS observations with PWP output shows that the ocean behaves one-dimensionally above the Pacific layer of the Beaufort Gyre. Despite agreement with the MIZMAS-forced PWP, SIZRS observations remain fresher to 100m than do outputs from MIZMAS and ECCO.2. The shapes of seasonal cycles in SIZRS salinity and temperature agree with MIZMAS and ECCO.2 model outputs despite differences in the values of each. However, the seasonal change of surface albedo is not high enough resolution to accurately drive the PWP. Use of ice albedo

  13. Erosional history of Cape Halkett and contemporary monitoring of bluff retreat, Beaufort Sea coast, Alaska

    USGS Publications Warehouse

    Jones, Benjamin M.; Arp, Christopher D.; Beck, Richard A.; Grosse, Guido; Webster, James M.; Urban, Frank E.

    2009-01-01

    Cape Halkett is located along the Beaufort Sea at the end of a low-lying tundra landscape. The area has been subject to major modifications over the last century as a result of erosion and migration of the coastline inland. Long-term mean annual erosion rates (1955-2009) for the entire cape are 7.6 m/yr, with a gradual increase in rates over the first five time periods of remotely sensed imagery analyzed and a large increase during the most recent time period. Division of the cape into three distinct coastal zones shows very different erosional patterns: the northeast-facing segment (Zone 1) showing a consistent and large increase; the southeast-facing segment (Zone 3) showing a gradual increase with recent, heightened erosion rates; and the east-facing segment (Zone 2) showing decreased rates due to the reformation of a sand and gravel spit. Monitoring of bluff erosion with time-lapse photography, differential GPS surveys, terrestrial and bathymetric surveys, and water level, sea and permafrost temperature data provide insights into the processes driving contemporary patterns of erosion and will provide valuable information for the prediction of future shoreline positions.

  14. Estuarine Nitrogen Dynamics Along the Alaskan Beaufort Sea Coast: Seasonal Patterns and Potential Climate Change Effects

    NASA Astrophysics Data System (ADS)

    McClelland, J. W.; Connelly, T. L.; Crump, B. C.; Kellogg, C.; Dunton, K. H.

    2014-12-01

    Seasonal runoff and sea-ice cover create highly dynamic estuarine conditions in the Arctic. Studies focusing on major systems such as the Mackenzie have demonstrated how these variables interact to influence nutrient supply and uptake dynamics. Far less is known about the seasonality of smaller estuarine systems in the Arctic. Data collected from lagoons along the eastern Alaska Beaufort Sea coast show that salinities range from near zero in the spring to as high as 50 in the winter. Runoff and sea-ice thaw in the spring create highly stratified conditions, with hyper-saline bottom waters persisting through the summer in some locations. These variations in physical conditions are accompanied by variations in nitrogen availability within the lagoons. High concentrations of ammonium, and to a lesser extent nitrate, build up under the ice during the winter months. These nutrients are rapidly depleted during the ice break-up period and remain low throughout the summer. Concentrations of organic nitrogen, on the other hand, peak during the ice break-up period. While river inputs contribute directly to this nitrogen peak through the supply of land-derived organic matter, fatty acid markers also show that locally produced organic matter (primarily diatoms) peaks during the ice break-up period. Seasonal changes in nitrogen are accompanied by distinct shifts in microbial community composition as well as changes in stable isotope values of metazoan consumers. Changes in climate that are altering both runoff and sea-ice have the potential to influence the quantity and timing of nutrient availability and associated biological production in arctic coastal waters.

  15. Methylated Mercury in the Eastern Beaufort Sea of the Arctic Ocean: The Role of Local and Recent Organic Remineralization

    NASA Astrophysics Data System (ADS)

    Armstrong, D.; Wang, F.

    2012-12-01

    Mercury (Hg) is a major contaminant in the Arctic marine ecosystem. While extensive studies have been conducted on Hg in the Arctic's atmosphere and biota, far less is known about the distribution and dynamics of Hg species in the Arctic Ocean. Here we present vertical profiles for total Hg (HgT) and total methylated Hg (MeHgT; primarily monomethylmercury MMHg, but also including dimethylmercury DMHg) from the eastern Beaufort Sea of the Arctic Ocean at locations with differing sea ice conditions. The concentration of HgT ranged from 0.40 to 2.9 pM, with a surface enrichment that can be attributed to a combination of sea ice-modified atmospheric deposition and riverine input. The concentration of MeHgT ranged from <0.04 to 0.59 pM, with a sub-surface peak occurring at the same depth as a nutrient maximum and dissolved oxygen minimum which is consistent with the recent findings in the Pacific Ocean, Southern Ocean, and Mediterranean Sea. However, unlike the interior ocean regions, the nutrient maximum in the eastern Beaufort Sea is predominantly an advective feature produced over the Chukchi Shelf. Based on the short lifetime of MMHg in seawater, we propose that the MeHgT profile in the eastern Beaufort Sea reflects the local, short-term regeneration of labile organic matter (OM), and not the larger signal of organic regeneration advected from the Chukchi Sea in the halocline. The finding that MeHgT is produced locally, reflecting recent strength of OM cycling, not only explains wide variance in MeHgT in seawater and biota over time and space, but also implies that MeHgT could be used as an indicator of the recent export flux of labile OM.

  16. Physical and biological correlates of virus dynamics in the southern Beaufort Sea and Amundsen Gulf

    NASA Astrophysics Data System (ADS)

    Payet, Jérôme P.; Suttle, Curtis A.

    2008-12-01

    As part of the Canadian Arctic Shelf Exchange Study (CASES), we investigated the spatial and seasonal distributions of viruses in relation to biotic (bacteria, chlorophyll- a (chl a)) and abiotic variables (temperature, salinity and depth). Sampling occurred in the southern Beaufort Sea Shelf in the region of the Amundsen Gulf and Mackenzie Shelf, between November 2003 and August 2004. Bacterial and viral abundances estimated by epifluorescence microscopy (EFM) and flow cytometry (FC) were highly correlated ( r2 = 0.89 and r2 = 0.87, respectively), although estimates by EFM were slightly higher (FC = 1.08 × EFM + 0.12 and FC = 1.07 × EFM + 0.43, respectively). Viral abundances ranged from 0.13 × 10 6 to 23 × 10 6 ml - 1 , and in surface waters were ~ 2-fold higher during the spring bloom in May and June and ~ 1.5-fold higher during July and August, relative to winter abundances. These increases were coincident with a ~ 6-fold increase in chl a during spring and a ~ 4-fold increase in bacteria during summer. Surface viral abundances near the Mackenzie River were ~ 2-fold higher than in the Mackenzie Shelf and Amundsen Gulf regions during the peak summer discharge, concomitant with a ~ 5.5-fold increase in chl a (up to 2.4 μg l - 1 ) and a ~ 2-fold increase in bacterial abundance (up to 22 × 10 5 ml - 1 ). Using FC, two subgroups of viruses and heterotrophic bacteria were defined. A low SYBR-green fluorescence virus subgroup (V2) representing ~ 71% of the total viral abundance, was linked to the abundance of high nucleic acid fluorescence (HNA) bacteria (a proxy for bacterial activity), which represented 42 to 72% of the bacteria in surface layers. A high SYBR-green fluorescence viral subgroup (V1) was more related to high chl a concentrations that occurred in surface waters during spring and at stations near the Mackenzie River plume during the summer discharge. These results suggest that V1 infect phytoplankton, while most V2 are bacteriophages. On the

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

    PubMed

    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.

  18. Dramatic Weakening of the Pacific Water Boundary Current in the Beaufort Sea during the First Decade of the 2000s.

    NASA Astrophysics Data System (ADS)

    Pickart, R. S.; Brugler, E.; Moore, K.; Roberts, S.; Weingartner, T.; Statscewich, H.

    2014-12-01

    Pacific-origin water has profound impacts on the physical state andecosystem of the Western Arctic Ocean. The cold winter waterventilates the upper halocline and supplies nutrients that fuelprimary productivity, while the warm summer waters melt sea ice andsupply freshwater to the Beaufort Gyre. Here we use mooring datacollected as part of the Arctic Observing Network (AON) to examine theinterannual trends in the current over the period 2002-2011.Strikingly, the volume transport of the current has decreased by morethan 80%, despite the fact that the flow through Bering Strait hasincreased over this time period. The largest changes have occurred inthe summer months. Using atmospheric reanalysis fields and weatherstation data, we demonstrate that an increase in summer easterly windsis the primary cause for the reduction in transport, which is largelydictated by the behavior of the two atmospheric centers of action, theBeaufort High and Aleutian Low. Using additional mooring and shipboarddata, together with satellite fields, we argue that a significantportion of the mass and heat passing through Bering Strait in recentyears has been advected out of Barrow Canyon into the interior CanadaBasin - rather than entering the boundary current in the Beaufort Sea- where it is responsible for a significant portion of the increasedsea ice melt in the basin.

  19. Holocene History of the Bering Sea Bowhead Whale ( Balaena mysticetus) in Its Beaufort Sea Summer Grounds off Southwestern Victoria Island, Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Dyke, Arthur S.; Savelle, James M.

    2001-05-01

    The fossil remains of 43 bowhead whales were mapped on the raised beaches of western Wollaston Peninsula, Victoria Island, Canadian Arctic, near the historic summer range limit of the Bering Sea stock in the Beaufort Sea. The elevations and radiocarbon ages of the remains demonstrate that the bowhead ranged commonly into the region following the submergence of Bering Strait at ca. 10,000 14C yr B.P. until ca. 8500 14C yr B.P. During the same interval, bowheads ranged widely from the Beaufort Sea to Baffin Bay. Subsequently, no whales reached Wollaston Peninsula until ca. 1500 14C yr B.P. Late Holocene populations evidently were small, or occupations were brief, in comparison to those of the early Holocene. Although the late Holocene recurrence may relate to the expansion of pioneering Thule whalers eastward from Alaska, there are few Thule sites and limited evidence of Thule whaling in the area surveyed to support this suggestion.

  20. The Beaufort Sea fold-and-thrust belt, northwestern Canada: Implications for thrust-belt evolution

    SciTech Connect

    Root, K.G. )

    1991-06-01

    The northeasternmost segment of the Cordilleran thrust belt of western North American underlies the Beaufort Sea continental margin. Folds and associated northesat-directed thrusts in this region formed synchronously with Tertiary sedimentation. As a result, the times of fold development can be determined from reflection seismic data by analyzing lateral thickness changes in stratigraphic sequences of known ages, and onlap and truncation relationships at unconformities. Thrust faulting occurred throughout the late Paleocene-Pliocene. The abundant temporal data indicate the deformational seuqence was significantly differet from the simple, steplike, foreland-propagating model formulated in other less well-dated thrust belts. Many thrusts were active simultaneously, especially during the late Eocnee, when the region of active thrusting had an across-strike width of greater than 200 km. This observation calls into question the popular concept that only one thrust moves at a time as a thrust belt develops. The thrust belt propagated along, as well as across, strike. During the late Paleocene-middle Eocene, the area of active thrusting was bounded on the southeast by poorly imaged zones of right-lateral strike-slip faults that apparently are the northern offshore continuation of the Rapid fault array. The change in the age of thrusting along strike results in no obvious geometrical anomalies and could not be deduced without timing information. This has an important implication: temporal data cannot necessarily be projected along strike in a thrust belt.

  1. Zones of impact around icebreakers affecting beluga whales in the Beaufort Sea.

    PubMed

    Erbe, C; Farmer, D M

    2000-09-01

    A software model estimating zones of impact on marine mammals around man-made noise [C. Erbe and D. M. Farmer, J. Acoust. Soc. Am. 108, 1327-1331 (2000)] is applied to the case of icebreakers affecting beluga whales in the Beaufort Sea. Two types of noise emitted by the Canadian Coast Guard icebreaker Henry Larsen are analyzed: bubbler system noise and propeller cavitation noise. Effects on beluga whales are modeled both in a deep-water environment and a near-shore environment. The model estimates that the Henry Larsen is audible to beluga whales over ranges of 35-78 km, depending on location. The zone of behavioral disturbance is only slightly smaller. Masking of beluga communication signals is predicted within 14-71-km range. Temporary hearing damage can occur if a beluga stays within 1-4 km of the Henry Larsen for at least 20 min. Bubbler noise impacts over the short ranges quoted; propeller cavitation noise accounts for all the long-range effects. Serious problems can arise in heavily industrialized areas where animals are exposed to ongoing noise and where anthropogenic noise from a variety of sources adds up.

  2. Drilling and operational sounds from an oil production island in the ice-covered Beaufort sea.

    PubMed

    Blackwell, Susanna B; Greene, Charles R; Richardson, W John

    2004-11-01

    Recordings of sounds underwater and in air, and of iceborne vibrations, were obtained at Northstar Island, an artificial gravel island in the Beaufort Sea near Prudhoe Bay (Alaska). The aim was to document the levels, characteristics, and range dependence of sounds and vibrations produced by drilling and oil production during the winter, when the island was surrounded by shore-fast ice. Drilling produced the highest underwater broadband (10-10,000 Hz) levels (maximum= 124 dB re: 1 microPa at 1 km), and mainly affected 700-1400 Hz frequencies. In contrast, drilling did not increase broadband levels in air or ice relative to levels during other island activities. Production did not increase broadband levels for any of the sensors. In all media, broadband levels decreased by approximately 20 dB/tenfold change in distance. Background levels underwater were reached by 9.4 km during drilling and 3-4 km without. In the air and ice, background levels were reached 5-10 km and 2-10 km from Northstar, respectively, depending on the wind but irrespective of drilling. A comparison of the recorded sounds with harbor and ringed seal audiograms showed that Northstar sounds were probably audible to seals, at least intermittently, out to approximately 1.5 km in water and approximately 5 km in air.

  3. Aerial surveys of endangered whales in the Beaufort Sea, Fall 1989. Final report

    SciTech Connect

    Treacy, S.D.

    1990-11-01

    The OCSLA Amendments of 1978 (43 U.S.C. 1802) established a policy for the management of oil and natural gas in the OCS and for protection of the marine and coastal environments. The amended OCSLA authorizes the Secretary of the Interior to conduct studies in areas or regions of sales to ascertain the environmental impacts on the marine and coastal environments of the outer Continental Shelf and the coastal areas which may be affected by oil and gas development (43 U.S.C. 1346). The report describes field activities and data analyses for aerial surveys of bowhead whales conducted between 1 September 1989 and 20 October 1989 in the Beaufort Sea, primarily between 140 W. and 154 W. longitudes south of 72 N. latitude. Ice cover during September and October 1989 was exceptionally light. A total of 215 bowhead whales, 104 belukha whales, 9 bearded seals, 84 ringed seals, and 32 unidentified pinnipeds were observed in 1989 during 98.70 hours of survey effort that included 38.10 hours on randomized transects. The last sighting of a bowhead whale made during the survey occurred in open water on 19 October 1989. No whales were sighted during a subsequent flight on 20 October 1989. Estimated median and mean water depths were shallower than for previous surveys (1982-1989). This is consistent with a trend for whales to be located in shallower water during years of generally light ice cover.

  4. Acoustic and visual surveys for bowhead whales in the western Beaufort and far northeastern Chukchi seas

    NASA Astrophysics Data System (ADS)

    Moore, Sue E.; Stafford, Kathleen M.; Munger, Lisa M.

    2010-01-01

    Two types of passive-acoustic survey were conducted to investigate the seasonal occurrence of bowhead whales ( Balaena mysticetus) in the western Beaufort and far northeastern Chukchi seas: (1) an over-winter (2003-04) survey using autonomous recorders deployed northeast of Barrow, Alaska, and (2) a summertime dipping-hydrophone survey along the 2005 NOAA Ocean Exploration (OE) cruise track northwest of Barrow. The longest continuous sampling period from the over-winter survey was 3 October 2003 to 12 May 2004. During that period, bowhead whale calls were recorded from 3 to 23 October, intermittently on 6-7 and 22-23 November, then not again until 25 March 2004. Bowhead calls were recorded almost every hour from 19 April to 12 May 2004, with a call rate peak on 30 April ( ca. 9400 calls) and a few instances of patterned calling (or, "song") detected in early May. Bowhead whale calls were never detected during the NOAA OE cruise, but calls of beluga whales ( Delphinapterus leucas) were recorded at 3 of 16 acoustic stations. Opportunistic visual surveys for marine mammals were also conducted during the NOAA OE cruise from the ship (65 h) and helicopter (7.8 h), resulting in single sightings of bowhead whales (3-5 whales), beluga (16-20 whales), walrus (1), polar bear (2=sow/cub), and 17 sightings of 87 ringed seals from the ship and 15 sightings of 67 ringed seals from the helicopter.

  5. Size distribution of absorbing and fluorescing DOM in Beaufort Sea, Canada Basin

    NASA Astrophysics Data System (ADS)

    Gao, Zhiyuan; Guéguen, Céline

    2017-03-01

    The molecular weight (MW) of dissolved organic matter (DOM) is considered as an important factor affecting the bioavailability of organic matter and associated chemical species. Colored DOM (CDOM) MW distribution was determined, for the first time, in the Beaufort Sea (Canada Basin) by asymmetrical flow field-flow fractionation (AF4) coupled with online diode array ultra violet-visible photometer and offline fluorescence detectors. The apparent MW ranged from 1.07 to 1.45 kDa, congruent with previous studies using high performance size exclusion chromatography and tangential flow filtration. Interestingly, a minimum in MW was associated with the Pacific Summer Waters (PSW), while higher MW was associated with the Pacific Winter Waters (PWW). The Arctic Intermediate Waters (AIW) did not show any significant change in MW and fluorescence intensities distribution between stations, suggesting homogeneous DOM composition in deep waters. Three fluorescence components including two humic-like components and one protein-like component were PARAFAC-validated. With the increase of MW, protein-like fluorescence component became more dominant while the majority remained as marine/microbially derived humic-like components. Overall, it is concluded that water mass origin influenced DOM MW distribution in the Arctic Ocean.

  6. Reprocessing of multi-channel seismic-reflection data collected in the Beaufort Sea

    USGS Publications Warehouse

    Agena, W.F.; Lee, Myung W.; Hart, P.E.

    2000-01-01

    Contained on this set of two CD-ROMs are stacked and migrated multi-channel seismic-reflection data for 65 lines recorded in the Beaufort Sea by the United States Geological Survey in 1977. All data were reprocessed by the USGS using updated processing methods resulting in improved interpretability. Each of the two CD-ROMs contains the following files: 1) 65 files containing the digital seismic data in standard, SEG-Y format; 2) 1 file containing navigation data for the 65 lines in standard SEG-P1 format; 3) an ASCII text file with cross-reference information for relating the sequential trace numbers on each line to cdp numbers and shotpoint numbers; 4) 2 small scale graphic images (stacked and migrated) of a segment of line 722 in Adobe Acrobat (R) PDF format; 5) a graphic image of the location map, generated from the navigation file; 6) PlotSeis, an MS-DOS Application that allows PC users to interactively view the SEG-Y files; 7) a PlotSeis documentation file; and 8) an explanation of the processing used to create the final seismic sections (this document).

  7. Marine heat flow measurements across subsea permafrost limit in the eastern Mackenzie Trough, Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Kim, Y. G.; Hong, J. K.; Jin, Y. K.; Riedel, M.; Melling, H.; Kang, S. G.; Dallimore, S.

    2015-12-01

    Marine heat flow measurements using a 5 m-long Ewing-type heat probe were made during Korean icebreaker R/V Araon's Arctic expeditions (ARA04C in 2013 and ARA05B in 2014) to better know the shallow subsurface thermal structure in the eastern slope of Mackenzie Trough, the Canadian Beaufort Sea, in which associative geological processes of permafrost degradation and gas hydrate dissociation occur because of long-term warming since the Last Glacial Maximum. Heat flow in the continental slope was collected for the first time and is rather higher than those from deep boreholes (up to a few km below the seafloor) in the continental shelf. However, the smaller geothermal gradient and thermal conductivity were observed from sites along a transect line across permafrost limit on the eastern slope of the trough. It is noted that geothermal gradients are relatively constant in the vicinity of permafrost limit but are much smaller (even minus) only at deeper depths with positive bottom water temperature. Reason for such distribution is unclear yet. Based on observed geothermal gradient and bottom water temperature, permafrost table shown in subbottom profile seems to be controlled not by temperature. On the other hand, our finding of permafrost evidence on the other subbottom profile located landward may support that permafrost limit in the trough is along with ~100 m isobath.

  8. The origin, distribution, and depositional history of gravel deposits on the Beaufort Sea Continental Shelf, Alaska

    USGS Publications Warehouse

    Rodeick, Craig A.

    1979-01-01

    Two distinct gravel populations are present on the Beaufort Sea continental shelf. First, a geographically arcuate deposit that is convex seaward has been designated as the Chert Facies. This deposit is restricted to landward of the 10 meter bathymetric contour and west of Heald Point. The Chert Facies, originally a fluvial gravel deposit and probably part of the basal transgressive, represents reworked Gubik Formation. The Chert Facies is derived from the Brooks Range. The second population is the Dolomite Facies. This facies is a blanket deposit covering much of the shelf and occurs in most water depths greater than 10 meters. The Dolomite Facies extends on land into the Quaternary Gubik Formation east of Prudhoe Bay and probably to Point Barrow. Rocks of the Dolomite Facies are exotic to Alaska and represent ice rafted clasts. The distribution of the Dolomite Facies shelf gravel indicates an easterly source compatible with a proposed provenance surrounding the Amundsen Gulf of the Canadian Archipelago. Radiocarbon dates from undisturbed sediment underlying the gravel on the upper slope indicate that low Holocene sedimentation rates are the reason for gravel exposure in this region and on the outer shelf. Considerations of sea level fluctuations, possible times available for the transportation of gravel from the proposed source area to the study area, and radiocarbon dates indicate influxes of ice rafted debris during the mid-Wisconsin transgression and probably between 15, 000-10,000 years B. P. Correlation of the Gubik Formation at Heald Point with the Barrow unit of the Gubik Formation at Point Barrow on the basis of incorporated dolomite and orthoquartzite clasts is suggested.

  9. Trophic transfer of persistent organochlorine contaminants (OCs) within an Arctic marine food web from the southern Beaufort-Chukchi Seas.

    PubMed

    Hoekstra, P F; O'Hara, T M; Fisk, A T; Borgå, K; Solomon, K R; Muir, D C G

    2003-01-01

    Stable isotope values (13C, 15N) and concentrations of persistent organochlorine contaminants (OCs) were determined to evaluate the near-shore marine trophic status of biota and biomagnification of OCs from the southern Beaufort-Chukchi Seas (1999-2000) near Barrow, AK. The biota examined included zooplankton (Calanus spp.), fish species such as arctic cod (Boreogadus saida), arctic char (Salvelinus alpinus), pink salmon (Oncorhynchus gorbuscha), and fourhorn sculpin (Myoxocephalus quadricornis), along with marine mammals, including bowhead whales (Balaena mysticetus), beluga whales (Delphinapterus leucas), ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). The isotopically derived trophic position of biota from the Beaufort-Chukchi Seas marine food web, avian fauna excluded, is similar to other coastal food webs in the Arctic. Concentrations of OCs in marine mammals were significantly greater than in fish and corresponded with determined trophic level. In general, OCs with the greatest food web magnification factors (FWMFs) were those either formed due to biotransformation (e.g. p,p'-DDE, oxychlordane) or considered recalcitrant (e.g. -HCH, 2,4,5-Cl substituted PCBs) in most biota, whereas concentrations of OCs that are considered to be readily eliminated (e.g. -HCH) did not correlate with trophic level. Differences in physical-chemical properties of OCs, feeding strategy and possible biotransformation were reflected in the variable biomagnification between fish and marine mammals. The FWMFs in the Beaufort-Chukchi Seas region were consistent with reported values in the Canadian Arctic and temperate food webs, but were statistically different than FWMFs from the Barents and White Seas, indicating that the spatial variability of OC contamination in top-level marine Arctic predators is attributed to differences in regional sources of contamination rather than trophic position.

  10. Stopover ecology of Semipalmated Sandpipers (Calidris pusilla) at coastal deltas of the Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Churchwell, Roy T.

    Avian migration is one of the wonders of the natural world. Stored fats are the main source of nutrients and fuel for avian migration and it is assumed the fat deposition at stopover sites is a critical component of a successful migration. Stopover sites are crucial in the successful migration of many birds, but particularly for arctic-breeding shorebirds that migrate long distances from breeding to wintering grounds. Despite the importance of stopover sites, it is often difficult to determine the importance of these sites to migrating shorebirds. I investigated three aspects of stopover ecology of Semipalmated Sandpipers (Calidris pusilla) foraging at coastal deltas on the Beaufort Sea coast, Alaska. First, I quantified the spatial and temporal distribution and abundance of the benthic macroinvertebrate community living within the mudflats. I found that there were two ecological groups of macroinvertebrates using river deltas, one originated in terrestrial freshwater habitats and most importantly could withstand freezing in delta sediments over the winter, and the other originated from the marine environment, could not withstand freezing and had to migrate to intertidal habitats each summer from deeper water areas that did not freeze over the winter. Stable isotope analysis allowed me to describe the origin of carbon consumed by invertebrates in intertidal habitats. I predicted freshwater invertebrates would consume terrestrial carbon, and marine invertebrates would consume marine carbon, but I found that both groups utilized the same carbon, which was a mixture of terrestrial and marine sources. My second research question determined the importance of delta foraging habitat for fall migrating Semipalmated Sandpipers. I mapped the temporal distribution and abundance of birds and quantified this relationship to invertebrate distribution and abundance. I researched fattening rates of shorebirds by measuring triglycerides in the blood of shorebirds I captured. I

  11. Plankton ecosystem functioning and nitrogen fluxes in the most oligotrophic waters of the Beaufort Sea, Arctic Ocean: a modeling study

    NASA Astrophysics Data System (ADS)

    Le Fouest, V.; Zakardjian, B.; Xie, H.; Raimbault, P.; Joux, F.; Babin, M.

    2012-10-01

    The Arctic Ocean (AO) undergoes profound changes of its physical and biotic environments due to climate change. The greater light exposure and stratification alter its plankton ecosystem structure, functioning and productivity promoting oligotrophy in some areas as the Beaufort Sea. A one-dimension (1-D) physical-biological coupled model based on the large multiparametric database of the Malina project in the Beaufort Sea was used (i) to infer the functioning and nitrogen fluxes within the summer plankton ecosystem and (ii) to assess the model sensitivity to key light-associated processes involved in nutrient recycling and phytoplankton growth. The coupled model suggested that ammonium photochemically produced from photosensitive dissolved organic nitrogen (i.e. photoammonification process) was a necessary nitrogen source to achieve the observed levels of microbial biomass and production. It contributed to ca. two-thirds and one-third of the simulated surface (0-10 m) and depth-integrated primary and bacterial production, respectively. The model also suggested that carbon to chlorophyll ratios for small (< 5 μm) phytoplankton (ca. 15-45 g g-1) lower than those commonly used in biogeochemical models applied to the AO were required to simulate the observed herbivorous versus microbial food web competition and realistic nitrogen fluxes in the Beaufort Sea oligotrophic waters. In face of accelerating Arctic warming, more attention should be paid in the future to the mechanistic processes involved in food webs and functional groups competition, nutrient recycling and primary production in poorly productive waters of the AO as they are expected to expand rapidly.

  12. Bioaccumulation of petroleum hydrocarbons in arctic amphipods in the oil development area of the Alaskan Beaufort Sea.

    PubMed

    Neff, Jerry M; Durell, Gregory S

    2012-04-01

    An objective of a multiyear monitoring program, sponsored by the US Department of the Interior, Bureau of Ocean Energy Management was to examine temporal and spatial changes in chemical and biological characteristics of the Arctic marine environment resulting from offshore oil exploration and development activities in the development area of the Alaskan Beaufort Sea. To determine if petroleum hydrocarbons from offshore oil operations are entering the Beaufort Sea food web, we measured concentrations of hydrocarbons in tissues of amphipods, Anonyx nugax, sediments, Northstar crude oil, and coastal peat, collected between 1999 and 2006 throughout the development area. Mean concentrations of polycyclic aromatic hydrocarbons (PAH), saturated hydrocarbons (SHC), and sterane and triterpane petroleum biomarkers (StTr) were not significantly different in amphipods near the Northstar oil production facility, before and after it came on line in 2001, and in amphipods from elsewhere in the study area. Forensic analysis of the profiles (relative composition and concentrations) of the 3 hydrocarbon classes revealed that hydrocarbon compositions were different in amphipods, surface sediments where the amphipods were collected, Northstar crude oil, and peat from the deltas of 4 North Slope rivers. Amphipods and sediments contained a mixture of petrogenic, pyrogenic, and biogenic PAH. The SHC in amphipods were dominated by pristane derived from zooplankton, indicating that the SHC were primarily from the amphipod diet of zooplankton detritus. The petroleum biomarker StTr profiles did not resemble those in Northstar crude oil. The forensic analysis revealed that hydrocarbons in amphipod tissues were not from oil production at Northstar. Hydrocarbons in amphipod tissues were primarily from their diet and from river runoff and coastal erosion of natural diagenic and fossil terrestrial materials, including seep oils, kerogens, and peat. Offshore oil and gas exploration and development

  13. Modern erosion rates and loss of coastal features and sites, Beaufort Sea coastline, Alaska

    USGS Publications Warehouse

    Jones, Benjamin M.; Hinkel, Kenneth M.; Arp, C.D.; Eisner, Wendy R.

    2008-01-01

    This study presents modern erosion rate measurements based upon vertical aerial photography captured in 1955, 1979, and 2002 for a 100 km segment of the Beaufort Sea coastline. Annual erosion rates from 1955 to 2002 averaged 5.6 m a-1. However, mean erosion rates increased from 5.0 m a-1 in 1955-79 to 6.2 m a-1 in 1979-2002. Furthermore, from the first period to the second, erosion rates increased at 60% (598) of the 992 sites analyzed, decreased at 31% (307), and changed less than ?? 30 cm at 9% (87). Historical observations and quantitative studies over the past 175 years allowed us to place our erosion rate measurements into a longer-term context. Several of the coastal features along this stretch of coastline received Western place names during the Dease and Simpson expedition in 1837, and the majority of those features had been lost by the early 1900s as a result of coastline erosion, suggesting that erosion has been active over at least the historical record. Incorporation of historical and modern observations also allowed us to detect the loss of both cultural and historical sites and modern infrastructure. U.S. Geological Survey topographic maps reveal a number of known cultural and historical sites, as well as sites with modern infrastructure constructed as recently as the 1950s, that had disappeared by the early 2000s as a result of coastal erosion. We were also able to identify sites that are currently being threatened by an encroaching coastline. Our modern erosion rate measurements can potentially be used to predict when a historical site or modern infrastructure will be affected if such erosion rates persist. ?? The Arctic Institute of North America.

  14. Benthic Gouge Marks in the Canadian Beaufort Sea: Associations Between Whales and Methane Seeps?

    NASA Astrophysics Data System (ADS)

    Smalls, P. T.; Paull, C. K.; Dallimore, S.

    2015-12-01

    Numerous distinctive depressions were observed on the seafloor during twenty-eight remotely operated vehicle (ROV) dives conducted on the shelf edge and upper slope of the Canadian Beaufort Sea. Surface ship and autonomous underwater vehicle (AUV) multibeam bathymetric maps were used to identify potential methane seepage sites, such as areas with persistent water column acoustic anomalies and the tops of mud volcanoes. ROV dives were conducted at these sites and at background sites for stratigraphic sampling. The high abundance of these distinctive depressions stimulated an analysis of the video observations made on these ROV dives. Depressions were analyzed to document their characteristics, to help determine their origin, and to establish whether their frequency varies with bottom type. One hundred fifty-two of the depressions observed had shared characteristics consisting of an "oval-shaped" depression with raised ridged edges that extended laterally along the flanks, and traces of uplifted sediment either in or around the depression. Similar depressions have been called "gouge marks" and attributed to bottom feeding beaked whales in previous studies. The size and water depth of the measured depressions matched well with beak sizes and feeding depths of beaked whale species known to exist in this area. This supports the conclusion that beaked whales created the depressions. The occurrence of these gouge marks and the estimates of the total area observed on these ROV dives (~45,000 m2), suggests they are common (e.g., ~4,000 per km2) features on the seafloor in this area of the Arctic. Gouges were also found 2.25 times more often at suspected methane seep-sites when normalized for depth and area. This suggests that the whales are preferentially attracted to seepage sites. While the reason for this possible preferential feeding behavior is unknown, it provides an intriguing avenue for further research.

  15. Importance of the eastern Alaskan Beaufort Sea to feeding bowhead whales, 1985. Final report, June 1985-May 1986

    SciTech Connect

    Richardson, W.J.

    1986-05-01

    The two-year project is designed to quantify what proportion of the energy requirements of Western Arctic bowheads is provided by food acquired in the Eastern part of the Alaskan Beaufort Sea. The report describes results from Year 1 fieldwork in September and early October 1985. Water masses were studied by boat-based sampling and by airborne and satellite remote sensing. Zooplankton composition, biomass, distribution, patchiness, and energy content were documented by boat-based sampling. The distribution, numbers and activities of bowheads were determined by aerial surveys and behavioral observations. Bowheads probably consume several times more food there in some other years.

  16. A Summary Comparison of Active Acoustic Detections and Visual Observations of Marine Mammals in the Canadian Beaufort Sea.

    PubMed

    Pyć, Cynthia D; Geoffroy, Maxime; Knudsen, Frank R

    2016-01-01

    Fisheries sonar was used to determine the applicability of active acoustic monitoring (AAM) for marine mammal detection in the Canadian Beaufort Sea. During 170 h of simultaneous observation by marine mammal observers and active acoustic observation, 119 Balaena mysticetus (bowheads) and 4 Delphinapterus leucas (belugas) were visually sighted, while 59 acoustic signals of bowheads were detected by AAM operators. Observations and detection of seals were also recorded. Comparative results indicate that commercially available active acoustic systems can detect seals at distances up to 500 m and large baleen whales at distances up to 2 km.

  17. Prediction of drilling site-specific interaction of industrial acoustic stimuli and endangered whales: Beaufort Sea (1985). Final report, July 1985-March 1986

    SciTech Connect

    Miles, P.R.; Malme, C.I.; Shepard, G.W.; Richardson, W.J.; Bird, J.E.

    1986-10-01

    Research was performed during the first year (1985) of the two-year project investigating potential responsiveness of bowhead and gray whales to underwater sounds associated with offshore oil-drilling sites in the Alaskan Beaufort Sea. The underwater acoustic environment and sound propagation characteristics of five offshore sites were determined. Estimates of industrial noise levels versus distance from those sites are provided. LGL Ltd. (bowhead) and BBN (gray whale) jointly present zones of responsiveness of these whales to typical underwater sounds (drillship, dredge, tugs, drilling at gravel island). An annotated bibliography regarding the potential effects of offshore industrial noise on bowhead whales in the Beaufort Sea is included.

  18. Catalogue of polar bear (Ursus maritimus) maternal den locations in the Beaufort Sea and neighboring regions, Alaska, 1910-2010

    USGS Publications Warehouse

    Durner, George M.; Fischbach, Anthony S.; Amstrup, Steven C.; Douglas, David C.

    2010-01-01

    This report presents data on the approximate locations and methods of discovery of 392 polar bear (Ursus maritimus) maternal dens found in the Beaufort Sea and neighboring regions between 1910 and 2010 that are archived by the U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska. A description of data collection methods, biases associated with collection method, primary time periods, and spatial resolution are provided. Polar bears in the Beaufort Sea and nearby regions den on both the sea ice and on land. Standardized VHF surveys and satellite radio telemetry data provide a general understanding of where polar bears have denned in this region over the past 3 decades. Den observations made during other research activities and anecdotal reports from other government agencies, coastal residents, and industry personnel also are reported. Data on past polar bear maternal den locations are provided to inform the public and to provide information for natural resource agencies in planning activities to avoid or minimize interference with polar bear maternity dens.

  19. Rapid coastal erosion on the Beaufort Sea coast: A triple whammy induced by climate change (Invited)

    NASA Astrophysics Data System (ADS)

    Anderson, R. S.; Wobus, C. W.; Overeem, I.; Clow, G. D.; Urban, F. E.; Stanton, T. P.

    2009-12-01

    The effects of climate change on landscape evolution can be pronounced in polar regions due to amplification of warming at high latitudes and sensitivity of ice-rich landscapes to warming. Documented coastal erosion rates exceeding 20-30 m/yr suggest that the effects of climate change are already being felt along northern coastlines. We seek to combine direct observational evidence of coastal retreat with relevant environmental information to generate predictive models capable of describing how these erosion processes respond to climate change. We study a section of the Beaufort Sea coastline roughly midway between Point Barrow and Prudhoe Bay. Three-to five-meter high, ice-rich silty bluffs have been eroding at a consistent rate of 15-25 m/yr through two years of direct monitoring. Our onshore data includes time-lapse photography, GPS-located flag lines, meteorological observations, bluff substrate properties, and size distributions of eroded blocks. Offshore, we use models and measurements of sea-ice coverage, bathymetry, sea surface temperature, and wave dynamics. Time-lapse films collected during the summers of 2008 and 2009 indicate that episodic block failure during storm events is superimposed on a slow, steady notching of the base of the ice-rich bluffs, which appears to be driven primarily by melting from relatively warm seawater. Block failure occurs preferentially along ice wedges. Once the blocks have toppled, thermal disintegration by warm nearshore waters occurs within days. The nearshore water responsible for melting the permafrost-rich coastline is very shallow; the local shelf slopes at less than 1 m/km. The water is commonly opaque due to suspended silt: light extinction depth scales of decimeters suggest that solar radiation should be efficiently absorbed in surface waters. Nearshore temperatures display distinct diurnal histories, and are vertically uniform, implying that they are well mixed. Variations in water level are dominated by storm

  20. Methane Seepage From the Arctic Shelf; 20 Years of Research on the Beaufort Sea Margin

    NASA Astrophysics Data System (ADS)

    Lorenson, T. D.; Paull, C. K.; Collett, T. S.; Dallimore, S. R.

    2008-12-01

    The U. S. Geological Survey has lead or played major roles in several efforts over the past 20 years to find geochemical evidence for gas hydrate dissociation on the Beaufort Sea shelf, a region of complex and varied geologic features that include: 1) several river deltas entering the Arctic Ocean, the largest of which is the Mackenzie River, 2) submerged continental shelf underlain by permafrost, 3) known petroleum systems of northern Alaska and the Mackenzie River Delta - Canada, 4), submerged pingo-like features (PLF's ) and, 5) pockmark fields. The results of these studies show that gas hydrate is present and that methane source can be both microbial and thermogenic. In light of our rapidly changing climate, the instability and potential methane release from Arctic gas hydrate deposits are reemerging as pivotal uncertainties. On the Alaskan Beaufort Shelf in water depths or about 10 m or less, methane concentrations in seawater are elevated relative to atmosphere. This methane likely originates from microbial degradation of organic matter deposited by rivers or coastal currents, and may be associated with organics in destabilized from recently thawed submerged shelf permafrost. In deeper water, north and west of the Prudhoe Bay area, some exceptionally high bottom water methane concentrations were measured with carbon isotopic signatures very similar (about -46 to -48‰) to gas hydrate sampled from the Mount Elbert 01 gas hydrate test well drilled in 2007 in the same area. This methane is presumably associated with the Prudhoe Bay gas hydrate and petroleum system, and likely from either gas hydrate dissociation or simple gas migration. Gas venting in and around the Mackenzie River delta is associated with offshore Pingo-like features (PLF's) and pockmarks. These PLF's resemble onshore pingos, but with an unknown origin. The region is underlain by an active petroleum system, submerged shelf permaforst, and gas hydrate. Methane concentrations are elevated in

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

    NASA Astrophysics Data System (ADS)

    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

  2. Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence

    USGS Publications Warehouse

    Hart, Patrick E.; Pohlman, John W.; Lorenson, T.D.; Edwards, Brian D.

    2011-01-01

    Gas hydrate was recovered from the Alaskan Beaufort Sea slope north of Camden Bay in August 2010 during a U.S. Coast Guard Cutter Healy expedition (USCG cruise ID HLY1002) under the direction of the U.S. Geological Survey (USGS). Interpretation of multichannel seismic (MCS) reflection data collected in 1977 by the USGS across the Beaufort Sea continental margin identified a regional bottom simulating reflection (BSR), indicating that a large segment of the Beaufort Sea slope is underlain by gas hydrate. During HLY1002, gas hydrate was sampled by serendipity with a piston core targeting a steep-sided bathymetric high originally thought to be an outcrop of older, exposed strata. The feature cored is an approximately 1100m diameter, 130 m high conical mound, referred to here as the Canning Seafloor Mound (CSM), which overlies the crest of a buried anticline in a region of sub-parallel compressional folds beneath the eastern Beaufort outer slope. An MCS profile shows a prominent BSR upslope and downslope from the mound. The absence of a BSR beneath the CSM and occurrence of gas hydrate near the summit indicates that free gas has migrated via deep-rooted thrust faults or by structural focusing up the flanks of the anticline to the seafloor. Gas hydrate recovered from near the CSM summit at a subbottom depth of about 5.7 meters in a water depth of 2538 m was of nodular and vein-filling morphology. Although the hydrate was not preserved, residual gas from the core liner contained >95% methane by volume when corrected for atmospheric contamination. The presence of trace C4+hydrocarbons (<0.1% by volume) confirms at least a minor thermogenic component. Authigenic carbonates and mollusk shells found throughout the core indicate sustained methane-rich fluid advection and possible sediment extrusion contributing to the development of the mound. Blister-like inflation of the seafloor caused by formation and accumulation of shallow hydrate lenses is also a likely factor in CSM

  3. Hematology of southern Beaufort Sea polar bears (2005-2007): biomarker for an Arctic ecosystem health sentinel.

    PubMed

    Kirk, Cassandra M; Amstrup, Steven; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M

    2010-09-01

    Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.

  4. Hematology of southern Beaufort Sea polar bears (2005-2007): Biomarker for an arctic ecosystem health sentinel

    USGS Publications Warehouse

    Kirk, Cassandra M.; Amstrup, S.; Swor, Rhonda; Holcomb, Darce; O'Hara, T. M.

    2010-01-01

    Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ???5, than lactating adult females ages ???5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel. ?? 2010 International Association for Ecology and Health.

  5. Contribution of subsurface chlorophyll maxima to primary production in the coastal Beaufort Sea (Canadian Arctic): A model assessment

    NASA Astrophysics Data System (ADS)

    Martin, Johannie; Dumont, Dany; Tremblay, Jean-Éric

    2013-11-01

    Previous comprehensive investigations of the Canadian Arctic revealed that subsurface chlorophyll maxima (SCM) are widespread and long-lived structures that can contribute significantly to daily primary production in the water column. However, estimating the annual contribution of SCM to production with in situ or remote-sensing approaches is challenging in the high Arctic. For this reason and to estimate the impacts of fluctuating or changing environmental conditions on SCM, a numerical approach combining a turbulence model and an ecosystem model was implemented for the coastal Beaufort Sea. An ensemble analysis of simulations suggested that SCM contribute 65-90% of total annual primary production and that this proportion is weakly affected by ice regime, winter nitrogen (N) concentration, parameter values determining phytoplankton growth and decay or the physical forcing imposed, all varying within realistic values. Due to the persistent association between the SCM and the shallow nitracline, the pelagic ecosystem of the coastal Beaufort Sea is apparently characterized by a high ratio of new to total production, contrasting with the common assumption that oligotrophic systems are predominantly supported by recycled N and regenerated production. This study demonstrated that the use of a simple model in combination with in situ data leads to novel insights into biogeochemical processes that are otherwise very difficult to measure and track.

  6. Quaternary sedimentation of the Alaskan Beaufort shelf: Influence of regional tectonics, fluctuating sea levels, and glacial sediment sources

    USGS Publications Warehouse

    Dinter, D.A.

    1985-01-01

    The offshore stratigraphy of the Quaternary Gubik Formation of Arctic Alaska has been studied on high-resolution seismic profiles with a maximum sub-seafloor penetration of about 100 m. In general, marine transgressive subunits of the Gubik Formation are wedge-shaped on the shelf, thickening slightly seaward to the shelf break, beyond which they are offset by landslides and slumps. Beneath the eastern third of the Alaskan Beaufort shelf, active folding has created two persistent structural depressions, the Eastern and Western Wedge Terranes, in which the wedge morphology is especially well developed. The youngest transgressive marine wedge, which was deposited in such a way as to fill these depressions, leaving a generally flat present-day shelf surface, is inferred to be late Wisconsin or younger in age because it overlies a prominent disconformity interpreted to have been formed during the late Wisconsin glacial sea-level minimum. The thickness of this youngest wedge, Unit A, locally exceeds 40 m on the outer shelf, yet apparently relict gravel deposits collected from its seabed surface indicate that the depositional rate is presently quite low on the middle and outer shelf. Lithologies of the gravels are exotic to Alaska, but similar to suites exposed in the Canadian Arctic Islands. These observations suggest a depositional scenario in which the retreating Laurentide Ice Sheet shed sediment-laden icebergs from the Canadian Arctic Islands into the Arctic Ocean following the late Wisconsin glacial maximum. These bergs were then rafted westward by the Beaufort Gyre and grounded on the Alaskan shelf by northeasterly prevailing winds. Especially large numbers of bergs accumulated in the wedge terrane embayments-created as sea level rose-and melted there, filling the embayments with their sedimentary cargo. As glacial retreat slowed, depositional rates on the shelf dwindled. This mode of deposition in the Alaskan Beaufort wedge terranes may be typical of early post

  7. Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

    DTIC Science & Technology

    2015-09-30

    interpret airborne electromagnetic induction and ice-profiling sonar from the region. The project also contributes ice thickness and ice core data sets...However, we will make use of airborne electromagnetic (AEM) data from the Tuktoyaktuk and Barrow regions to examine differences in the thickness of ice...calculated back- and forward-trajectories of sea ice at different points along the flight tracks of airborne electromagnetic (AEM) ice thickness

  8. Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

    USGS Publications Warehouse

    2014-01-01

    Polar bears (Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004-2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

  9. Slope Edge Deformation and Permafrost Dynamics Along the Arctic Shelf Edge, Beaufort Sea, Canada

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Riedel, M.; Melling, H.

    2015-12-01

    The shelf of the Canadian Beaufort Sea is underlain by relict offshore permafrost that formed in the long intervals of terrestrial exposure during glacial periods. At the shelf edge the permafrost thins rapidly and also warms. This area has a very distinct morphology that we attribute to both the formation and degradation of ice bearing permafrost. Positive relief features include circular to oval shaped topographic mounds, up to 10 m high and ~50 m in diameter which occur at a density of ~6 per km2. Intermixed are circular topographic depressions up to 20 m deep. This topography was investigated using an autonomous underwater vehicle that provides 1 m horizontal resolution bathymetry and chirp profiles, a remotely operated vehicle to document seafloor textures, and sediment cores to sample pore waters. A consistent down-core freshening at rates of 14 to 96 mM Cl- per meter was found in these pore waters near the shelf edge. Downward extrapolation of these trends indicates water with ≤335 mM Cl- should occur at 2.3 to 22.4 m sub-seafloor depths within this shelf edge deformation band. Pore water with 335 mM Cl- or less freezes at -1.4°C. As bottom water temperatures in this area are persistently (<-1.4°C) cold and ground ice was observed in some core samples, we interpret the volume changes associated with mound formation are in part due to pore water freezing. Thermal models (Taylor et al., 2014) predict brackish water along the shelf edge may be sourced in relict permafrost melting under the adjacent continental shelf. Buoyant brackish water is hypothesized to migrate along the base of the relict permafrost, to emerge at the shelf edge and then refreeze when it encounters the colder seafloor. Expansion generated by the formation of ice-bearing permafrost generates the positive relief mounds and ridges. The associated negative relief features may be related to permafrost dynamics also. Permafrost dynamics may have geohazard implications that are unique to the

  10. Sharing Remote and Local Information for Tracking Spring Breakup in the Mackenzie Delta and Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Forbes, D. L.; Whalen, D.; Fraser, P.

    2015-12-01

    The Mackenzie Delta is the second largest on the Arctic Ocean, covering 13 000 km2. The annual flood regime in the delta is dominated by the spring snowmelt freshet and associated ice breakup, as water from the south arrives in the ice-covered delta and spreads over bottomfast and adjacent floating sea ice at the delta front. The complex processes of water-ice interaction, flow partitioning, and overbank flooding to replenish waters in 43 000 delta lakes threaten community, transportation, subsistence, and energy infrastructure in the delta. The annual breakup season is a time of rejuvenation, excitement, and anxiety for delta residents and stakeholders. To track the progress of breakup and meet the need for knowledge dissemination to the local communities, a Mackenzie-Beaufort breakup newsletter has been produced by Natural Resources Canada on a quasi-daily basis during the May-June spring flood season for 10 years, and distributed to an e-mail list that grew to over 300 subscribers. This provides near real-time tracking of water levels and breakup using on-line gauges (Environment Canada), daily MODIS satellite imagery (NASA), Landsat imagery (USGS) and intermittent radar imagery (various sources). In earlier years, information was also supplied from field programs operating in the delta during breakup, but changing priorities and funding have reduced the number of outside researchers present during these critical weeks. Meanwhile the number of local contributors has grown, providing observations and photographs to share with the local, regional and global readership. In this way the newsletter evolved into a two-way communication tool and community portal. The newsletter is a chronicle of each breakup season and a key resource for territorial and municipal managers, subsistence organizations, and emergency response agencies, with routine requests for specific imagery in areas of concern. With the completion of 10 years under the present model, we are exploring

  11. Origin of pingo-like features on the Beaufort Sea shelf and their possible relationship to decomposing methane gas hydrates

    USGS Publications Warehouse

    Paull, C.K.; Ussler, W.; Dallimore, S.R.; Blasco, S.M.; Lorenson, T.D.; Melling, H.; Medioli, B.E.; Nixon, F.M.; McLaughlin, F.A.

    2007-01-01

    The Arctic shelf is currently undergoing dramatic thermal changes caused by the continued warming associated with Holocene sea level rise. During this transgression, comparatively warm waters have flooded over cold permafrost areas of the Arctic Shelf. A thermal pulse of more than 10??C is still propagating down into the submerged sediment and may be decomposing gas hydrate as well as permafrost. A search for gas venting on the Arctic seafloor focused on pingo-like-features (PLFs) on the Beaufort Sea Shelf because they may be a direct consequence of gas hydrate decomposition at depth. Vibracores collected from eight PLFs had systematically elevated methane concentrations. ROV observations revealed streams of methane-rich gas bubbles coming from the crests of PLFs. We offer a scenario of how PLFs may be growing offshore as a result of gas pressure associated with gas hydrate decomposition. Copyright 2007 by the American Geophysical Union.

  12. Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992-2009; sources and atmospheric flux

    USGS Publications Warehouse

    Lorenson, Thomas D.; Greinert, Jens; Coffin, Richard B.

    2016-01-01

    Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of the Arctic Ocean during eleven surveys spanning the years of 1992-1995 and 2009. During ice-free periods, methane flux from the Beaufort shelf varies from 0.14 to 0.43 mg CH4 m-2 day-1. Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m-2 day-1. Seasonal buildup of methane under ice can produce short-term fluxes of methane from the Beaufort shelf that varies from 0.28 to 1.01 to mg CH4 m-2 day-1. Scaled-up estimates of minimum methane flux from the Beaufort Sea and pan-Arctic shelf for both ice-free and ice-covered periods range from 0.02 Tg CH4 yr-1 and 0.30 Tg CH4 yr-1 respectively to maximum fluxes of 0.18 Tg CH4 yr-1 and 2.2 Tg CH4 yr-1 respectively. A methane flux of 0.36 Tg CH4 yr-1from the deep Arctic Ocean was estimated using data from 1993-94. The flux can be as much as 2.35 Tg CH4 yr-1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ~560 Tg CH4 yr-1. There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.

  13. Sea Ice Floe Distribution in the Beaufort and Chukchi Seas Measured by ERS-1 SAR

    NASA Technical Reports Server (NTRS)

    Holt, Benjamin; Rio, Marie-Hne

    1996-01-01

    This study examines the spatial and temporal character of sea ice floe size distribution during summer melt, important variables for understanding the summer heat and mass budgets and the distribution of heat between the vertical and horizontal ice melt. Preliminary results are presented that indicate the gradual decrease in medium size floes (1-5 km diameters) and a fairly steady maintenance of floes smaller than 1 km in diameter over the primary summer months within the central pack ice region. The latter result indicates that smaller floes continue to melt or decay rather than accumulate, indicating the importance of dynamics in affecting ice melt.

  14. Quantifying the Bering Strait Oceanic Fluxes and their Impacts on Sea-Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014

    DTIC Science & Technology

    2014-09-30

    Impacts on Sea- Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014 Rebecca Woodgate Polar Science...from the Pacific, are critical to the water properties of the Chukchi Sea, act as a trigger of sea- ice melt in the Chukchi, provide a subsurface...source of heat to the Arctic in winter (with possible impacts on sea- ice ), and are a major component of freshwater input to the Arctic (Figures 1 and 2

  15. Evidence for Freshwater Discharge at a Gas Hydrate-Bearing Seafloor Mound on the Beaufort Sea Continental Slope

    NASA Astrophysics Data System (ADS)

    Pohlman, J.; Lorenson, T. D.; Hart, P. E.; Ruppel, C. D.; Joseph, C.; Torres, M. E.; Edwards, B. D.

    2011-12-01

    A deep-water (~2.5 km water depth) seafloor mound located ~150 km offshore of the North Slope Alaska, informally named the Canning Seafloor Mound (CSM), contains a documented occurrence of gas hydrate; the first from the Beaufort Sea. Gases and porewater extracted from cores taken at the CSM summit several months after core recovery provided surprisingly consistent and outstanding results. Gases migrating into the structure are likely a mixture of primary microbial gas formed by carbonate reduction and secondary microbial gas formed from degraded thermogenic gases, linking the system to deep oil and gas generation (see companion abstract by Lorenson et al.). Pore fluids extracted from the base of the 572 cm-long hydrate-bearing core had chloride values as low as 160 mM, which equates to an ~80% freshwater contribution. Low chloride values, often interpreted as a product of gas hydrate dissociation in hydrate-bearing cores, were coincident with sulfate values in excess of 1 mM and as high as 22 mM (seawater is ~28mM). High sulfate concentrations generally indicate an absence of methane, and, thus, gas hydrate; therefore, an allochthonous source of freshwater is required. Potential sources are clay mineral dehydration, clay membrane filtration and/or a meteoric water influx. Several lines of evidence indicate the Canning Seafloor Mound is connected to either a deep, landward freshwater aquifer or to an unusually fresh oil field brine. First, Na/Cl ratios decrease from marine (~0.86) near the seafloor to distinctly higher values of 1.20 at the bottom of the core. Second, clay dehydration and ion filtration processes have not, to our knowledge, yielded fluids as fresh as measured in these near-seafloor sediments. Third, and most importantly, δ18O-δD systematics of fluid end members are entirely consistent with a meteoric water source and inconsistent with trends expected for either gas hydrate dissociation, smectite to illite clay dewatering or ion filtration

  16. Surface and basal sea ice melt from autonomous buoy arrays during the 2014 sea ice retreat in the Beaufort/Chukchi Seas

    NASA Astrophysics Data System (ADS)

    Maksym, T. L.; Wilkinson, J.; Hwang, P. B.

    2014-12-01

    As the Arctic continues its transition to a seasonal ice cover, the nature and role of the processes driving sea ice retreat are expected to change. Key questions revolve around how the coupling between dynamics and thermodynamic processes and potential changes in the role of melt ponds contribute to an accelerated seasonal ice retreat. To address these issues, 44 autonomous platforms were deployed in four arrays in the Beaufort Sea in March, 2014, with an additional array deployed in August in the Chukchi Sea to monitor the evolution of ice conditions during the seasonal sea ice retreat. Each "5-dice" array included four or five co-sited ice mass balance buoys (IMB) and wave buoys with digital cameras, and one automatic weather station (AWS) at the array center. The sensors on these buoys, combined with satellite imagery monitoring the large-scale evolution of the ice cover, provide a near-complete history of the processes involved in the seasonal melt of sea ice. We present a preliminary analysis of the contributions of several key processes to the seasonal ice decay. The evolution of surface ponding was observed at several sites with differing ice types and surface morphologies. The records of surface melt and ice thickness demonstrate a key role of ice type in driving the evolution of the ice cover. Analysis of the surface forcing and estimates of solar energy partitioning between the surface and upper ocean is compared to the surface and basal mass balance from the IMBs. The role of ice divergence and deformation in driving sea ice decay - in particular its role in accelerating thermodynamic melt processes - is discussed.

  17. Dose Estimates from Ingestion of Marine and Terrestrial Animals Harvested in the Beaufort Sea and Northwestern Alaska

    SciTech Connect

    W. C. T. Inkret; M. E. Schillaci; D. W. Efurd; M. E. Ennis; M. J. Hameedi; J. M. Inkret; T. H. T. Little; G. Miller

    2000-11-01

    Between 1993 and 1995, marine and terrestrial animal samples were collected from the Beaufort Sea and northwest Alaska. These samples were analyzed at Los Alamos National Laboratory for the presence of the anthropogenic radionuclides, {sup 90}Sr, {sup 137}Cs, {sup 238}Pu, {sup 239+240}Pu, and {sup 241}Am. The measurement data were combined with food consumption rates based on survey results for populations residing in three northwest Alaskan communities and published age-dependent ingestion dose coefficients to estimate potential radiological impacts from the consumption of traditional animal foods harvested in this region. The results of this study indicate that committed equivalent doses to adults from {sup 90}Sr and {sup 137}Cs, due to consumption of traditional food sources are consistent with currently accepted estimates of average doses to adults in North America due to atmospheric nuclear weapons testing fallout.

  18. Importance of the eastern Alaskan Beaufort Sea to feeding bowhead whales, 1985-86. Final report, June 1985-August 1987

    SciTech Connect

    Richardson, W.J.

    1987-08-01

    The 2-year project was designed to quantify what proportion of the energy requirements of Western Arctic bowheads is provided by food acquired in the eastern part of the Alaskan Beaufort Sea. This final report presents the results from fieldwork in September - early October of 1985 and 1986. Water masses were studied by boat-based sampling and remote sensing. Zooplankton composition, biomass, distribution, patchiness and energy content were documented with nets and echosounders (a) over the continental shelf generally, and (b) near feeding bowheads. Whale distribution, numbers and activities were determined by aerial surveys and behavioral observations. Size segregation and residence times were studied by photogrammetry; five bowheads were radio tagged. Analyses of carbon-isotope ratios helped in tracing energy sources for bowheads.

  19. Evaluation of the anthropogenic radionuclide concentrations in sediments and fauna collected in the Beaufort Sea and northern Alaska

    SciTech Connect

    Efurd, D.W.; Miller, G.G.; Rokop, D.J.

    1997-07-01

    This study was performed to establish a quality controlled data set about the levels of radio nuclide activity in the environment and in selected biota in the U.S. Arctic. Sediment and biota samples were collected by the National Oceanic and Atmospheric Administration (NOAA), the National Biological Service, and the North Slope Borough`s Department of Wildlife Management to determine the impact of anthropogenic radionuclides in the Arctic. The results summarized in this report are derived from samples collected in northwest Alaska with emphasis on species harvested for subsistence in Barrow, Alaska. Samples were analyzed for the anthropogenic radionuclides {sup 90}Sr, {sup 137}Cs, {sup 238}Pu, {sup 239}Pu, {sup 240}Pu and {sup 241}Am. The naturally occurring radionuclides {sup 40}K, {sup 212}Pb and {sup 214}Pb were also measured. One goal of this study was to determine the amounts of anthropogenic radionuclides present in the Beaufort Sea. Sediment samples were isotopically fingerprinted to determine the sources of radio nuclide activities. Biota samples of subsistence and ecological value were analyzed to search for evidence of bio-accumulation of radionuclides and to determine the radiation exposures associated with subsistence living in northern Alaska. The anthropogenic radio nuclide content of sediments collected in the Beaufort Sea was predominantly the result of the deposition of global fallout. No other sources of anthropogenic radionuclides could be conclusively identified in the sediments. The anthropogenic radio nuclide concentrations in fish, birds and mammals were very low. Assuming that ingestion of food is an important pathway leading to human contact with radioactive contaminants and given the dietary patterns in coastal Arctic communities, it can be surmised that marine food chains are presently not significantly affected.

  20. MIZMAS: Modeling the Evolution of Ice Thickness and Floe Size Distributions in the Marginal Ice Zone of the Chukchi and Beaufort Seas

    DTIC Science & Technology

    2015-09-30

    zone (MIZ) of the Chukchi and Beaufort seas (CBS) on seasonal time scales . Our primary interest is the ability to realistically simulate the...historical evolution of the CBS MIZ ice–ocean system and its ITD and FSD from 1978 to the present to quantify and understand the large- scale changes that...Library (GFL) (pixel size 1 meter). We continued to seek to establish a relationship between the FSD at the large scale and the small scale

  1. Modeling plankton ecosystem functioning and nitrogen fluxes in the oligotrophic waters of the Beaufort Sea, Arctic Ocean: a focus on light-driven processes

    NASA Astrophysics Data System (ADS)

    Le Fouest, V.; Zakardjian, B.; Xie, H.; Raimbault, P.; Joux, F.; Babin, M.

    2013-07-01

    The Arctic Ocean (AO) undergoes profound changes of its physical and biotic environments due to climate change. In some areas of the Beaufort Sea, the stronger haline stratification observed in summer alters the plankton ecosystem structure, functioning and productivity, promoting oligotrophy. A one-dimension (1-D) physical-biological coupled model based on the large multiparametric database of the Malina project in the Beaufort Sea was used (i) to infer the plankton ecosystem functioning and related nitrogen fluxes and (ii) to assess the model sensitivity to key light-driven processes involved in nutrient recycling and phytoplankton growth. The coupled model suggested that ammonium photochemically produced from photosensitive dissolved organic nitrogen (i.e., photoammonification process) was a necessary nitrogen source to achieve the observed levels of microbial biomass and production. Photoammonification directly and indirectly (by stimulating the microbial food web activity) contributed to 70% and 18.5% of the 0-10 m and whole water column, respectively, simulated primary production (respectively 66% and 16% for the bacterial production). The model also suggested that variable carbon to chlorophyll ratios were required to simulate the observed herbivorous versus microbial food web competition and realistic nitrogen fluxes in the Beaufort Sea oligotrophic waters. In face of accelerating Arctic warming, more attention should be paid in the future to the mechanistic processes involved in food webs and functional group competition, nutrient recycling and primary production in poorly productive waters of the AO, as they are expected to expand rapidly.

  2. Distribution and diet of larval and juvenile Arctic cod ( Boreogadus saida) in the shallow Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Walkusz, Wojciech; Paulic, Joclyn E.; Williams, William J.; Kwasniewski, Slawomir; Papst, Michael H.

    2011-02-01

    The distribution and diet of larval and juvenile Arctic cod ( Boreogadus saida) were studied during summer 2005 in the coastal Canadian Beaufort Sea. A total of 275 individuals were captured and the highest abundance was observed at station depths of 20-30 m. This corresponds well with the location of the frontal zone where the Mackenzie River plume water and open sea water meet. Diet examinations were performed on 220 Arctic cod, which were found undamaged from sampling. We observed a gradual decrease in prey number per fish and increase in prey size as larvae grew which corresponded to a shift from Rotifera and nauplii towards larger copepodid stages. However, at all sizes, the larvae remain generalists and feed on a broad range of organisms. Environmental changes due to climate warming could have a two-fold impact on fish larvae feeding in the studied region. First, the potential for increased primary production may lead to increased zooplankton production that may impact the feeding and nutrition positively. On the other hand, greater discharge of turbid water from the Mackenzie River may reduce light penetration in the water column that may negatively influence the ability of visual predators to successively forage.

  3. Genetic variation, relatedness, and effective population size of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

    USGS Publications Warehouse

    Cronin, M.A.; Amstrup, Steven C.; Talbot, S.L.; Sage, G.K.; Amstrup, K.S.

    2009-01-01

    Polar bears (Ursus maritimus) are unique among bears in that they are adapted to the Arctic sea ice environment. Genetic data are useful for understanding their evolution and can contribute to management. We assessed parentage and relatedness of polar bears in the southern Beaufort Sea, Alaska, with genetic data and field observations of age, sex, and mother-offspring and sibling relationships. Genotypes at 14 microsatellite DNA loci for 226 bears indicate that genetic variation is comparable to other populations of polar bears with mean number of alleles per locus of 7.9 and observed and expected heterozygosity of 0.71. The genetic data verified 60 field-identified mother-offspring pairs and identified 10 additional mother-cub pairs and 48 father-offspring pairs. The entire sample of related and unrelated bears had a mean pairwise relatedness index (rxy) of approximately zero, parent-offspring and siblings had rxy of approximately 0.5, and 5.2% of the samples had rxy values within the range expected for parent-offspring. Effective population size (Ne = 277) and the ratio of Ne to total population size (Ne/N = 0.182) were estimated from the numbers of reproducing males and females. Ne estimates with genetic methods gave variable results. Our results verify and expand field data on reproduction by females and provide new data on reproduction by males and estimates of relatedness and Ne in a polar bear population. ?? The American Genetic Association. 2009. All rights reserved.

  4. Change in the Beaufort Sea ecosystem: Diverging trends in body condition and/or production in five marine vertebrate species

    NASA Astrophysics Data System (ADS)

    Harwood, L. A.; Smith, T. G.; George, J. C.; Sandstrom, S. J.; Walkusz, W.; Divoky, G. J.

    2015-08-01

    Studies of the body condition of five marine vertebrate predators in the Beaufort Sea, conducted independently during the past 2-4 decades, suggest each has been affected by biophysical changes in the marine ecosystem. We summarize a temporal trend of increasing body condition in two species (bowhead whale subadults, Arctic char), in both cases influenced by the extent and persistence of annual sea ice. Three other species (ringed seal, beluga, black guillemot chicks), consumers with a dietary preference for Arctic cod, experienced declines in condition, growth and/or production during the same time period. The proximate causes of these observed changes remain unknown, but may reflect an upward trend in secondary productivity, and a concurrent downward trend in the availability of forage fishes, such as the preferred Arctic cod. To further our understanding of these apparent ecosystem shifts, we urge the use of multiple marine vertebrate species in the design of biophysical sampling studies to identify causes of these changes. Continued long-term, standardized monitoring of vertebrate body condition should be paired with concurrent direct (stomach contents) or indirect (isotopes, fatty acids) monitoring of diet, detailed study of movements and seasonal ranges to establish and refine baselines, and identification of critical habitats of the marine vertebrates being monitored. This would be coordinated with biophysical and oceanographic sampling, at spatial and temporal scales, and geographic locations, that are relevant to the home range, critical habitats and prey of the vertebrate indicator species showing changes in condition and related parameters.

  5. Aerial surveys of endangered whales in the Alaskan Chukchi and western Beaufort Seas, 1990. Final report, Oct-Nov 90

    SciTech Connect

    Moore, S.E.; Clarke, J.T.

    1991-06-01

    In keeping with the National Environmental Policy Act (1969), the Marine Mammal Protection Act (1972) and the Endangered Species Act (1973), the OCS Lands Act Amendments (1978) established a management policy that included studies in OCS lease sale areas to ascertain potential environmental impacts of oil and gas development on OCS marine coastal environments. The Minerals Management Service (MMS) is the agency responsible for these studies and for the leasing of submerged Federal lands. The report summarizes the 1990 investigations of the distribution, abundance, migration, behavior and habitat relationships of endangered whales in the Alaskan Chukchi and western Beaufort Seas (hereafter, study area); 1990 was the second of a three year (1989-91) study. The Bering Sea stock of bowhead whales (Balaena mysticetus) was the principal species studied, with incidental sightings of all other marine mammals routinely recorded. The 1990 season was compromised by circumstances that restricted the availability of the survey aircraft (Grumman Goose, model G21G) to the period 26 October - 7 November; opportunistic surveys were flown in the study area from 3-25 October. In 1990, there were 14 sightings of 19 bowheads from 9-29 October; 5 whales, including 2 calves, were seen north of the study area. One gray whale, 110 belukhas and 53 polar bears were also seen. Over nine survey seasons (1982-90), there were 240 sightings of 520 bowhead whales and 148 sightings of 398 gray whales.

  6. Prevalence and spatio-temporal variation of an alopecia syndrome in polar bears (Ursus maritimus) of the southern Beaufort Sea.

    PubMed

    Atwood, Todd; Peacock, Elizabeth; Burek-Huntington, Kathy; Shearn-Bochsler, Valerie; Bodenstein, Barbara; Beckmen, Kimberlee; Durner, George

    2015-01-01

    Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears (Ursus maritimus) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.

  7. Prevalence and spatio-temporal variation of an alopecia syndrome in polar bears (Ursus maritimus) of the southern Beaufort Sea

    USGS Publications Warehouse

    Atwood, Todd C.; Peacock, Elizabeth; Burek, K.A.; Shearn-Bochsler, Valerie I.; Bodenstein, Barbara L.; Beckmen, Kimberlee B.; Durner, George M.

    2015-01-01

    Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears (Ursus maritimus) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.

  8. Snailfishes of the Careproctus rastrinus complex (Liparidae): redescriptions of seven species in the North Pacific Ocean region, with the description of a new species from the Beaufort Sea.

    PubMed

    Orr, James Wilder; Kai, Yoshiaki; Nakabo, Tetsuji

    2015-09-16

    Herein we review and recognize as valid all previously described species of the Careproctus rastrinus complex based on morphological evidence, provide diagnoses and descriptions of all species, describe a new species from the Beaufort Sea, and address the misapplication of several names throughout the area. In particular, the name C. rastrinus is restricted to populations of the western Pacific and is known conclusively only from the Sea of Okhotsk. Careproctus acanthodes, from the Sea of Japan and Sea of Okhotsk, and C. pellucidus, from the Pacific Ocean side of northern Japan, are resurrected from synonymy with C. rastrinus. Populations of the eastern Pacific previously routinely identified as C. rastrinus are recognized under two names: C. scottae, a name that is applied to deeper water Bering Sea, Aleutian Islands, and eastern Pacific populations having a postorbital pore, and Careproctus phasma, applied to shallow water populations of the Bering Sea and Gulf of Alaska lacking a postorbital pore. Although we consider Careproctus spectrum valid, the species has been routinely misidentified and is presently known only from the type series. Careproctus lerikimae is a new species described from the Beaufort Sea, diagnosed from other species of the C. rastrinus complex by the absence of the postorbital pore and higher median fin and vertebral counts.

  9. Toward a Predictive Model of Arctic Coastal Retreat in a Warming Climate, Beaufort Sea, Alaska

    DTIC Science & Technology

    2009-01-01

    local decadal time series of sea ice coverage and sea surface temperature. Sea ice concentrations have been analyzed using Nimbus 7-SMMR /SSM/I and...As a first step we used Nimbus 7-SMMR /SSM/I and DMSP SSMI Passive Microwave data to assess sea ice concentration around the Drew Point coast...Fetch Length at at Drew Point for different stages over the summer season 2008 is reconstructed from Nimbus -7 Passive microwave data, 2008 has open

  10. Benthic Food Webs of the Chukchi and Beaufort Seas: Relative Importance of Ultimate Carbon Sources in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Dunton, K. H.; Schonberg, S. V.; Mctigue, N.; Bucolo, P. A.; Connelly, T. L.; McClelland, J. W.

    2014-12-01

    Changes in sea-ice cover, coastal erosion, and freshwater run-off have the potential to greatly influence carbon assimilation pathways and affect trophic structure in benthic communities across the western Arctic. In the Chukchi Sea, variations in the duration and timing of ice cover affect the delivery of ice algae to a relatively shallow (40-50 m) shelf benthos. Although ice algae are known as an important spring carbon subsidy for marine benthic fauna, ice algal contributions may also help initiate productivity of an active microphytobenthos. Recent studies provide clear evidence that the microphytobenthos are photosynthetically active, and have sufficient light and nutrients for in situ growth. The assimilation of benthic diatoms from both sources may explain the 13C enrichment observed in benthic primary consumers throughout the northern Chukchi. On the eastern Beaufort Sea coast, shallow (2-4 m) estuarine lagoon systems receive massive subsidies of terrestrial carbon that is assimilated by a benthic fauna of significant importance to upper trophic level species, but again, distinct 13C enrichment in benthic primary consumers suggests the existence of an uncharacterized food source. Since ice algae are absent, we believe the 13C enrichment in benthic fauna is caused by the assimilation of benthic microalgae, as reflected in seasonally high benthic chlorophyll in spring under replete light and nutrient conditions. Our observations suggest that changes in ice cover, on both temporal and spatial scales, are likely to have significant effects on the magnitude and timing of organic matter delivery to both shelf and nearshore systems, and that locally produced organic matter may become an increasingly important carbon subsidy that affects trophic assimilation and secondary ecosystem productivity.

  11. Habitat use and foraging patterns of molting male Long-tailed Ducks in lagoons of the central Beaufort Sea, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Reed, John; Deborah Lacroix,; Richard Lanctot,

    2016-01-01

    From mid-July through September, 10 000 to 30 000 Long-tailed Ducks (Clangula hyemalis) use the lagoon systems of the central Beaufort Sea for remigial molt. Little is known about their foraging behavior and patterns of habitat use during this flightless period. We used radio transmitters to track male Long-tailed Ducks through the molt period from 2000 to 2002 in three lagoons: one adjacent to industrial oil field development and activity and two in areas without industrial activity. We found that an index to time spent foraging generally increased through the molt period. Foraging, habitat use, and home range size showed similar patterns, but those patterns were highly variable among lagoons and across years. Even with continuous daylight during the study period, birds tended to use offshore areas during the day for feeding and roosted in protected nearshore waters at night. We suspect that variability in behaviors associated with foraging, habitat use, and home range size are likely influenced by availability of invertebrate prey. Proximity to oil field activity did not appear to affect foraging behaviors of molting Long-tailed Ducks.

  12. Mercury concentrations in Southern Beaufort Sea polar bears: variation based on stable isotopes of carbon and nitrogen.

    PubMed

    Cardona-Marek, Tamara; Knott, Katrina K; Meyer, Benjamin E; O'Hara, Todd M

    2009-07-01

    Total Hg concentration was measured in hair and whole blood of 52 adult Southern Beaufort Sea polar bears (Ursus maritimus) captured in the spring of 2005. Stable isotopic signatures (i.e., 13C/12C, delta13C; 15N/14N, delta15N) in hair and two blood compartments (packed blood cells/clot and serum) were determined to assess the variation of Hg concentrations among polar bears in relation to their feeding ecology and other biological factors. Concentrations of Hg in hair and blood (2.2-23.9 microg/g dry wt and 0.007-0.213 microg/g wet wt, respectively) were within the range of values previously reported for polar bears in Canada and East Greenland. Mercury concentration in hair from females was higher than that in hair from males, and concentration was related to interactions between delta13C, delta15N, and longitude of capture location. Mercury concentrations in hair were inversely correlated to delta13C in hair and blood, suggesting that polar bears with greater total Hg concentrations fed more on pelagic prey, such as ringed seals or beluga whale, than on benthic prey. Variability in Hg concentrations in polar bear hair and blood may be the result of intraspecific or regional variation in prey selection rather than strictly trophic level interactions.

  13. Sounds from an oil production island in the Beaufort Sea in summer: characteristics and contribution of vessels.

    PubMed

    Blackwell, Susanna B; Greene, Charles R

    2006-01-01

    The objective of this study was to determine the levels, characteristics, and range dependence of underwater and in-air sounds produced during the open-water seasons of 2000-2003 by the Northstar oil development, located in nearshore waters of the Alaskan Beaufort Sea. Specifically, sounds originating at the island itself (from construction, drilling, and oil production activities) were compared with sounds produced by vessels performing island support. Sounds were obtained with boat-based recordings (at distances up to 37 km from Northstar), a cabled hydrophone (distance approximately 450 m), and with autonomous seafloor recorders (distance approximately 22 km). Vessels (crew boat, tugs, self-propelled barges) were the main contributors to the underwater sound field and were often detectable underwater as much as approximately 30 km offshore. Without vessels, broadband island sounds reached background values at 2-4 km. Island sound levels showed more variation (lower min, higher max) during construction than during drilling and production. In-air broadband measurements were not affected by the presence of vessels and reached background values 1-4 km from Northstar. However, one airborne tone (81 Hz) believed to originate at Northstar was still detectable in the spectrum 37 km away.

  14. Larval and early juvenile fish distribution and assemblage structure in the Canadian Beaufort Sea during July-August, 2005

    NASA Astrophysics Data System (ADS)

    Paulic, Joclyn E.; Papst, Michael H.

    2013-11-01

    The distribution and composition of marine larval and early juvenile fish were investigated during a multidisciplinary project conducted in the nearshore Canadian Beaufort Sea in July and August, 2005. Larvae were sampled using replicate bongo net (500 μm) tows within 50 m water depth. A total of 458 larval fish representing seven families were captured.Multivariate statistical analyses revealed two distinct larval assemblages that were closely correlated to water mass category. The two larval fish assemblages were defined as coastal and estuarine. The coastal assemblage was dominated by Pacific Herring (Clupea pallasii) and was found in the shallow intense plume water mass. This area is greatly influenced by the Mackenzie River outflow. The estuarine assemblage was dominated by Arctic Cod (Boreogadus saida) and was typically found within the diffuse plume and oceanic water masses. Other larval fish families that were represented in the estuarine assemblage were Cottidae, Stichaeidae, Liparidae and Agonidae. Species richness and abundance was greater along the Toker transect in Kugmallit Bay than the Paktoa transect northwest of Garry Island in the Mackenzie Bay.

  15. Composition of the summer photosynthetic pico and nanoplankton communities in the Beaufort Sea assessed by T-RFLP and sequences of the 18S rRNA gene from flow cytometry sorted samples

    PubMed Central

    Balzano, Sergio; Marie, Dominique; Gourvil, Priscillia; Vaulot, Daniel

    2012-01-01

    The composition of photosynthetic pico and nanoeukaryotes was investigated in the North East Pacific and the Arctic Ocean with special emphasis on the Beaufort Sea during the MALINA cruise in summer 2009. Photosynthetic populations were sorted using flow cytometry based on their size and pigment fluorescence. Diversity of the sorted photosynthetic eukaryotes was determined using terminal-restriction fragment length polymorphism analysis and cloning/sequencing of the 18S ribosomal RNA gene. Picoplankton was dominated by Mamiellophyceae, a class of small green algae previously included in the prasinophytes: in the North East Pacific, the contribution of an Arctic Micromonas ecotype increased steadily northward becoming the only taxon occurring at most stations throughout the Beaufort Sea. In contrast, nanoplankton was more diverse: North Pacific stations were dominated by Pseudo-nitzschia sp. whereas those in the Beaufort Sea were dominated by two distinct Chaetoceros species as well as by Chrysophyceae, Pelagophyceae and Chrysochromulina spp.. This study confirms the importance of Arctic Micromonas within picoplankton throughout the Beaufort Sea and demonstrates that the photosynthetic picoeukaryote community in the Arctic is much less diverse than at lower latitudes. Moreover, in contrast to what occurs in warmer waters, most of the key pico- and nanoplankton species found in the Beaufort Sea could be successfully established in culture. PMID:22278671

  16. Wind and wave influences on sea ice floe size and leads in the Beaufort and Chukchi Seas during the summer-fall transition 2014

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Holt, Benjamin; Erick Rogers, W.; Thomson, Jim; Shen, Hayley H.

    2016-02-01

    Sea ice floe size distribution and lead properties in the Beaufort and Chukchi Seas are studied in the summer-fall transition 2014 to examine the impact on the sea ice cover from storms and surface waves. Floe size distributions are analyzed from MEDEA, Landsat8, and RADARSAT-2 imagery, with a resolution span of 1-100 m. Landsat8 imagery is also used to identify the orientation and spacing of leads. The study period centers around three large wave events during August-September 2014 identified by SWIFT buoys and WAVEWATCH III® model data. The range of floe sizes from different resolutions provides the overall distribution across a wide range of ice properties and estimated thickness. All cumulative floe size distribution curves show a gradual bending toward shallower slopes for smaller floe sizes. The overall slopes in the cumulative floe size distribution curves from Landsat8 images are lower than, while those from RADARSAT-2 are similar to, previously reported results in the same region and seasonal period. The MEDEA floe size distributions appeared to be sensitive to the passage of storms. Lead orientations, regardless of length, correlate slightly better with the peak wave direction than with the mean wave direction. Their correlation with the geostrophic wind is stronger than with the surface wind. The spacing between shorter leads correlates well with the local incoming surface wavelengths, obtained from the model peak wave frequency. The information derived shows promise for a coordinated multisensor study of storm effects in the Arctic marginal ice zone.

  17. Genetic variation, relatedness, and effective population size of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska.

    PubMed

    Cronin, Matthew A; Amstrup, Steven C; Talbot, Sandra L; Sage, George K; Amstrup, Kristin S

    2009-01-01

    Polar bears (Ursus maritimus) are unique among bears in that they are adapted to the Arctic sea ice environment. Genetic data are useful for understanding their evolution and can contribute to management. We assessed parentage and relatedness of polar bears in the southern Beaufort Sea, Alaska, with genetic data and field observations of age, sex, and mother-offspring and sibling relationships. Genotypes at 14 microsatellite DNA loci for 226 bears indicate that genetic variation is comparable to other populations of polar bears with mean number of alleles per locus of 7.9 and observed and expected heterozygosity of 0.71. The genetic data verified 60 field-identified mother-offspring pairs and identified 10 additional mother-cub pairs and 48 father-offspring pairs. The entire sample of related and unrelated bears had a mean pairwise relatedness index (r(xy)) of approximately zero, parent-offspring and siblings had r(xy) of approximately 0.5, and 5.2% of the samples had r(xy) values within the range expected for parent-offspring. Effective population size (N(e) = 277) and the ratio of N(e) to total population size (N(e)/N = 0.182) were estimated from the numbers of reproducing males and females. N(e) estimates with genetic methods gave variable results. Our results verify and expand field data on reproduction by females and provide new data on reproduction by males and estimates of relatedness and N(e) in a polar bear population.

  18. Seasonal spatial patterns in seabird and marine mammal distribution in the eastern Chukchi and western Beaufort seas: Identifying biologically important pelagic areas

    NASA Astrophysics Data System (ADS)

    Kuletz, Kathy J.; Ferguson, Megan C.; Hurley, Brendan; Gall, Adrian E.; Labunski, Elizabeth A.; Morgan, Tawna C.

    2015-08-01

    The Chukchi and Beaufort seas are undergoing rapid climate change and increased human activity. Conservation efforts for upper trophic level predators such as seabirds and marine mammals require information on species' distributions and identification of important marine areas. Here we describe broad-scale distributions of seabirds and marine mammals. We examined spatial patterns of relative abundance of seabirds and marine mammals in the eastern Chukchi and western Beaufort seas during summer (15 June-31 August) and fall (1 September-20 November) from 2007 to 2012. We summarized 49,206 km of shipboard surveys for seabirds and 183,157 km of aerial surveys for marine mammals into a grid of 40-km × 40-km cells. We used Getis-Ord Gi∗ hotspot analysis to test for cells with higher relative abundance than expected when compared to all cells within the study area. We identified cells representing single species and taxonomic group hotspots, cells representing hotspots for multiple species, and cells representing hotspots for both seabirds and marine mammals. The locations of hotspots varied among species but often were located near underwater canyons or over continental shelf features and slopes. Hotspots for seabirds, walrus, and gray whales occurred primarily in the Chukchi Sea. Hotspots for bowhead whales and other pinnipeds (i.e., seals) occurred near Barrow Canyon and along the Beaufort Sea shelf and slope. Hotspots for belugas occurred in both the Chukchi and Beaufort seas. There were three hotspots shared by both seabirds and marine mammals in summer: off Wainwright in the eastern Chukchi Sea, south of Hanna Shoal, and at the mouth of Barrow Canyon. In fall, the only identified shared hotspot occurred at the mouth of Barrow Canyon. Shared hotspots are characterized by strong fronts caused by upwelling and currents, and these areas can have high densities of euphausiids in summer and fall. Due to the high relative abundance of animals and diversity of taxa

  19. Velocity models and images using full waveform inversion and reverse time migration for the offshore permafrost in the Canadian shelf of Beaufort Sea, Arctic

    NASA Astrophysics Data System (ADS)

    Kang, S. G.; Hong, J. K.; Jin, Y. K.; Kim, S.; Kim, Y. G.; Dallimore, S.; Riedel, M.; Shin, C.

    2015-12-01

    During Expedition ARA05C (from Aug 26 to Sep 19, 2014) on the Korean icebreaker RV ARAON, the multi-channel seismic (MCS) data were acquired on the outer shelf and slope of the Canadian Beaufort Sea to investigate distribution and internal geological structures of the offshore ice-bonded permafrost and gas hydrates, totaling 998 km L-km with 19,962 shots. The MCS data were recorded using a 1500 m long solid-type streamer with 120 channels. Shot and group spacing were 50 m and 12.5 m, respectively. Most MCS survey lines were designed perpendicular and parallel to the strike of the shelf break. Ice-bonded permafrost or ice-bearing sediments are widely distributed under the Beaufort Sea shelf, which have formed during periods of lower sea level when portions of the shelf less than ~100m water depth were an emergent coastal plain exposed to very cold surface. The seismic P-wave velocity is an important geophysical parameter for identifying the distribution of ice-bonded permafrost with high velocity in this area. Recently, full waveform inversion (FWI) and reverse time migration (RTM) are commonly used to delineate detailed seismic velocity information and seismic image of geological structures. FWI is a data fitting procedure based on wave field modeling and numerical analysis to extract quantitative geophysical parameters such as P-, S-wave velocities and density from seismic data. RTM based on 2-way wave equation is a useful technique to construct accurate seismic image with amplitude preserving of field data. In this study, we suggest two-dimensional P-wave velocity model (Figure.1) using the FWI algorithm to delineate the top and bottom boundaries of ice-bonded permafrost in the Canadian shelf of Beaufort Sea. In addition, we construct amplitude preserving migrated seismic image using RTM to interpret the geological history involved with the evolution of permafrost.

  20. Toward a Predictive Model of Arctic Coastal Retreat in a Warming Climate, Beaufort Sea, Alaska

    DTIC Science & Technology

    2011-09-30

    conditions. We used Nimbus 7-SMMR /SSM/I and DMSP SSMI Passive Microwave data to assess sea ice concentration around the Drew Point coast. This...Figure 4. Fetch Length at Drew Point for different stages over the summer season 2008 is reconstructed from Nimbus -7 Passive microwave... cloud events. The air temperatures distinctly lag the insolation pattern, as the presence or absence of sea ice governs the continentality of the

  1. Current surges and seabed erosion near the shelf break in the Canadian Beaufort Sea: A response to wind and ice motion stress

    NASA Astrophysics Data System (ADS)

    Forest, Alexandre; Osborne, Philip D.; Curtiss, Gregory; Lowings, Malcolm G.

    2016-08-01

    Estimating the erosion potential of seabed sediments and the magnitude of the resulting suspended load in relation to current dynamics near the shelf break is a key issue for better understanding shelf-slope sediment transport. On the outer Mackenzie Shelf (Canadian Beaufort Sea, Arctic Ocean), a thin and discontinuous veneer of recent surficial clays overlie old glaciomarine sediments that further pinch out at the shelf edge. Gas and fluid venting is known to underlie part of sediment instability in the area, but recent mooring-based measurements also indicate that sediments near the shelf break are recurrently remobilized by strong subsurface currents. Here, we relate storms to the development of current surges that resulted in the abrupt resuspension of sediments at two locations along the shelf break. Near-bottom concentrations of suspended sediments were estimated using the acoustic backscatter of high-frequency acoustic Doppler current profilers deployed from September 2011 to September 2013 as part of the Beaufort Regional Environmental Assessment (BREA) program. Near-bottom currents near the shelf edge (140 to 150 m isobaths) were characterized by recurring episodes of elevated velocities (instantaneous speeds up to ~ 40-50 cm s-1) that were extensions of current surges (~ 60-80 cm s-1) occurring in the core of the shelfbreak jet located at ca. 90-120 m. Sudden peaks in suspended sediments (above 100 g m-3) corresponded closely with current surges in the near-bottom boundary layer (< 10 m) implying the local erosion of surficial sediments and the rapid advection or redeposition of the resuspended sediments. A range of apparent threshold velocities from 18 to 36 cm s-1 was calculated based on the relationship between suspended sediment concentrations and near-bottom current speeds. Two meteorological scenarios were identified to explain the current surges underlying these erosion events at the shelf edge: (1) Pacific or Arctic-born low pressure systems that

  2. Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Rogers, W. Erick; Thomson, Jim; Shen, Hayley H.; Doble, Martin J.; Wadhams, Peter; Cheng, Sukun

    2016-11-01

    A model for wind-generated surface gravity waves, WAVEWATCH III®, is used to analyze and interpret buoy measurements of wave spectra. The model is applied to a hindcast of a wave event in sea ice in the western Arctic, 11-14 October 2015, for which extensive buoy and ship-borne measurements were made during a research cruise. The model, which uses a viscoelastic parameterization to represent the impact of sea ice on the waves, is found to have good skill - after calibration of the effective viscosity - for prediction of total energy, but over-predicts dissipation of high frequency energy by the sea ice. This shortcoming motivates detailed analysis of the apparent dissipation rate. A new inversion method is applied to yield, for each buoy spectrum, the inferred dissipation rate as a function of wave frequency. For 102 of the measured wave spectra, visual observations of the sea ice were available from buoy-mounted cameras, and ice categories (primarily for varying forms of pancake and frazil ice) are assigned to each based on the photographs. When comparing the inversion-derived dissipation profiles against the independently derived ice categories, there is remarkable correspondence, with clear sorting of dissipation profiles into groups of similar ice type. These profiles are largely monotonic: they do not exhibit the "roll-over" that has been found at high frequencies in some previous observational studies.

  3. Food habits of Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) in the northeastern Chukchi and western Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Gray, Benjamin P.; Norcross, Brenda L.; Beaudreau, Anne H.; Blanchard, Arny L.; Seitz, Andrew C.

    2017-01-01

    Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) belong to Cottidae, the second most abundant fish family in the western Arctic. Although considered important in food webs, little is known about their food habits throughout this region. To address this knowledge gap, we examined and compared the diets of 515 Arctic staghorn sculpin and 422 shorthorn sculpin using stomachs collected over three summers in the northeastern Chukchi Sea (2010-2012) and one summer in the western Beaufort Sea (2011). We used permutational multivariate analysis of variance (PERMANOVA) and non-metric multidimensional scaling (nMDS) to compare sculpin diets between regions and selected size classes. Differences in mouth morphologies and predator size versus prey size relationships were examined using regression techniques. Arctic staghorn sculpin and shorthorn sculpin diet compositions differed greatly throughout the Chukchi and Beaufort Seas. Regardless of body size, the smaller-mouthed Arctic staghorn sculpin consumed mostly benthic amphipods and polychaetes, whereas the larger-mouthed shorthorn sculpin shifted from a diet composed of benthic and pelagic macroinvertebrates as smaller individuals to shrimps and fish prey as larger individuals. Within shared habitats, the sculpins appear to partition prey, either by taxa or size, in a manner that suggests no substantial overlap occurs between species. This study increases knowledge of sculpin feeding ecology in the western Arctic and offers regional, quantitative diet information that could support current and future food web modeling efforts.

  4. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2012-09-30

    Meric Srokosz, Alex West, Richard Wood, Axel Schweiger (2012), Assessment of Possibility and Impact of Rapid Climate Change in the Arctic Rep., 62 pp, UK MetOffice, Hadley Centre ...Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys Axel ...email: axel @apl.washington.edu Ron Lindsay Applied Physics Laboratory, University of Washington Jinlun Zhang Applied Physics Laboratory

  5. Statistical Aspects of Ice Gouging on the Alaskan Shelf of the Beaufort Sea,

    DTIC Science & Technology

    1983-09-01

    Another characteristic of’ tile d 0 data, whjich 0. t -, arid 0.2-rn s alues, %%ere decleted from the satir - might be anticipated fronm our earlier...Northi America, Sea O.C. Reed and .1.Sater , I ds. 1. Arlington, pp. 113-161. \\ irginia : A-rct ic Inlstilute of North A-merica, pp. Ko% acs, A. and l

  6. An oilspill risk analysis for the Beaufort Sea, Alaska (proposed sale 71)outer continental shelf lease area

    USGS Publications Warehouse

    Samuels, W.B.; Hopkins, Dorothy; Lanfear, K.J.

    1981-01-01

    An oilspill risk analysis was conducted to determine the relative environmental hazards of developing oil in different regions of the Beaufort Sea, Alaska, (Proposed Sale 71) Outer Continental Shelf (OCS) lease area. The probability of spill occurrences, likely movement of oil slicks, and locations of resources vulnerable to spilled oil were analyzed. The model predicted movement of the center of spill mass and estimated the times between spill occurrence and contact with various resources, to allow a qualitative assessment of oil characteristics at the time of contact; no direct computation was made of weathering and cleanup. The model also assumed that any oil spilled under ice would remain in place, unchanged, until spring breakup. Ice movements, or travel of oil under ice, if occurring, would affect the results in a manner not directly predictable at this time. The combined results of spill occurrence and spill movement predictions yielded estimates of the overall risks associated with development of the proposed lease area. Assuming that oil exists in the lease area (a 99.3-percent chance) it is estimated that the leasing of the tracts proposed for OCS Sale 71 will result in an expected 9.2 oilspills (of 1,000 barrels or larger) over the lease lifetime of 25 years. This estimate is based on historic oilspill accident data for platforms and pipelines on the U.S. OCS (Gulf of Mexico and California). The estimated probability that land will be contacted by one or more oilspills (of 1,000 barrels or larger) that have been at sea less than 30 days (not counting any time trapped under ice) is greater than 99.5 percent. If oilspill accident data for Prudhoe Bay, Alaska, is used in the analysis, it is estimated that 5.6 oilspills (1,000 barrels or larger) will occur over the lease lifetime. The estimated probability that one or more oilspills (1,000 barrels or larger)will occur and contact land is99 percent. The results of a recent experimental cleanup operation for

  7. Annual cycle and spatial trends in fatty acid composition of suspended particulate organic matter across the Beaufort Sea shelf

    NASA Astrophysics Data System (ADS)

    Connelly, Tara L.; Businski, Tara N.; Deibel, Don; Parrish, Christopher C.; Trela, Piotr

    2016-11-01

    Fatty acid profiles of suspended particulate organic matter (POM) were determined over an annual cycle (September 2003 to August 2004) on the Beaufort Sea shelf, Canadian Arctic. Special emphasis was placed on the nutritional quality of the fatty acid pool available to zooplankton by examining spatial and temporal patterns in the proportions of total polyunsaturated fatty acids (PUFA) and the essential fatty acids 22:6n-3 (DHA) and 20:5n-3 (EPA). EPA and DHA were the two most abundant PUFA throughout the study period. A log-ratio multivariate (LRA) analysis revealed strong structure in fatty acid profiles related to season and depth. Dominant fatty acids accounting for the observed trend included 18:5n-3, 18:4n-3, 16:1n-7, 20:5n-3, 18:0 and 20:3n-3. We observed a shift in fatty acid profiles from summer to autumn (e.g., from 16:1n-7 and EPA to 18:5n-3 and 18:4n-3) that likely corresponded to a shift in the relative importance of diatoms versus dinoflagellates, prymnesiophytes and/or prasinophytes to the POM pool. Fatty acid composition during winter was dominated by more refractory saturated fatty acids. A surprising finding was the depth and seasonal trend of 20:3n-3, which was higher in winter, aligned with 18:0 in the LRA, but behaved differently than other n-3 PUFA. We interpret fatty acid profiles during summer to be predominantly driven by phytoplankton inputs, whereas fatty acid profiles in winter were dominated by fatty acids that were left over after consumption and/or were generated by heterotrophs. The highest diatom inputs (EPA, the diatom fatty acid marker), n-3/n-6 ratios, and C16 PUFA index were located in an upwelling region off Cape Bathurst. This study is the first annual time series of fatty acid profiles of POM in Arctic seas, expanding our knowledge of the composition of POM throughout the dark season.

  8. Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-1

    NASA Technical Reports Server (NTRS)

    Reimnitz, E. (Principal Investigator); Barnes, P. W.

    1973-01-01

    The author has identified the following significant results. Northward flowing rivers of Alaska inundate extensive areas of sea ice during spring breakup. This process has been studied under the ERTS-1 program. Drainage of large volumes of fresh water through the ice at holes and cracks (strudel) causes scour depressions, over 4 m deep, and up to 20 m across in the sea floor below. Strudel scours occur within 30 km of river mouths, generally in areas where ERTS-1 imagery shows less potential for drifting ice to scour the bottom than elsewhere. The shapes and distribution patterns of strudel scours correspond with those of strudel seen in the ice canopy. Densities of scours are highest in the inner areas of overlfow. But strudel scours also occur outside of overflow areas mapped during the last several years. These must be very old. One strudel scour investigated by diving is surrounded by a rim, has vertical walls exposing a tundra horizon, and terminates at a gravel layer 4 m below the lagoon floor. Another terminates at a semi-consolidated layer of silty clay. The gravel and silty clay are pre-Holocene deposits. Mixing of Holocene marine with older sediments by vertical strudel flow causes great variability in sediment types over small areas. These observations complicate interpretation of shallow water deposits of cold climates.

  9. Assessing the potential impacts of declining Arctic sea ice cover on the photochemical degradation of dissolved organic matter in the Chukchi and Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Logvinova, Christie L.; Frey, Karen E.; Mann, Paul J.; Stubbins, Aron; Spencer, Robert G. M.

    2015-11-01

    A warming and shifting climate in the Arctic has led to significant declines in sea ice over the last several decades. Although these changes in sea ice cover are well documented, large uncertainties remain in how associated increases in solar radiation transmitted to the underlying ocean water column will impact heating, biological, and biogeochemical processes in the Arctic Ocean. In this study, six under-ice marine, two ice-free marine, and two ice-free terrestrially influenced water samples were irradiated using a solar simulator for 72 h (representing ~10 days of ambient sunlight) to investigate dissolved organic matter (DOM) dynamics from the Chukchi and Beaufort Seas. Solar irradiation caused chromophoric DOM (CDOM) light absorption at 254 nm to decrease by 48 to 63%. An overall loss in total DOM fluorescence intensity was also observed at the end of all experiments, and each of six components identified by parallel factor (PARAFAC) analysis was shown to be photoreactive in at least one experiment. Fluorescent DOM (FDOM) also indicated that the majority of DOM in under-ice and ice-free marine waters was likely algal-derived. Measurable changes in dissolved organic carbon (DOC) were only observed for sites influenced by riverine runoff. Losses of CDOM absorbance at shorter wavelengths suggest that the beneficial UV protection currently received by marine organisms may decline with the increased light transmittance associated with sea ice melt ponding and overall reductions of sea ice. Our FDOM analyses demonstrate that DOM irrespective of source was susceptible to photobleaching. Additionally, our findings suggest that photodegradation of CDOM in under-ice waters is not currently a significant source of carbon dioxide (CO2) (i.e., we did not observe systematic DOC loss). However, increases in primary production and terrestrial freshwater export expected under future climate change scenarios may cause an increase in CDOM quantity and shift in quality

  10. The polar bear management agreement for the southern Beaufort Sea: an evaluation of the first ten years of a unique conservation agreement

    USGS Publications Warehouse

    Brower, C.D.; Carpenter, A.; Branigan, M.L.; Calvert, W.; Evans, T.; Fischbach, A.S.; Nagy, J.A.; Schliebe, S.; Stirling, I.

    2002-01-01

    Polar bears (Ursus maritimus) of the southern Beaufort Sea population, distributed from approximately Icy Cape, west of Point Barrow, to Pearce Point, east of Paulatuk in Canada, are harvested by hunters from both countries. In Canada, quotas to control polar bear hunting have been in place, with periodic modifications, since 1968. In Alaska, passage of the United State Marine Mammal Protection Act (MMPA) of 1972 banned polar bear hunting unless done by Alaska Natives for subsistence. However, the MMPA placed no restrictions on numbers or composition of the subsistence hunt, leaving open the potential for an overharvest with no possible legal management response until the population was declared depleted. Recognizing that as a threat to the conservation of the shared polar bear population, the Inuvialuit Game Council from Canada and the North Slop Borough from Alaska negotiated and signed a user-to-user agreement, the Polar Bear Management Agreement for the Southern Beaufort Sea, in 1988. We reviewed the functioning of the agreement through its first 10 years and concluded that, overall, it has been successful because both the total harvest and the proportion of females in the harvest have been contained within sustainable limits. However, harvest monitoring needs to be improved in Alaska, and awareness of the need to prevent overharvest of females needs to be increased in both countries. This agreement is a useful model for other user-to-user conservation agreements.

  11. Biogeochemistry of near-bottom suspended particulate matter of the Beaufort Sea shelf (Arctic Ocean): C, N, P, δ 13C and fatty acids

    NASA Astrophysics Data System (ADS)

    Connelly, Tara L.; Deibel, Don; Parrish, Christopher C.

    2012-07-01

    The influence of the Mackenzie River on the source, composition, and distribution of dissolved nutrients and suspended particulate matter (SPM) in near-bottom waters on the Beaufort Sea shelf was determined by measuring particulate organic carbon (POC), particulate nitrogen (PN), particulate phosphorus (PP), elemental ratios (C:N, C:P, N:P), chlorophyll a, bulk δ 13C, and fatty acids. The Mackenzie River had a strong influence on the composition of SPM in near-bottom waters across the entire Canadian Beaufort Sea shelf, including the Amundsen Gulf. This influence was strongest at stations near the river mouth and decreased offshore and northeastward towards the Amundsen Gulf, as seen in SPM elemental concentrations, δ 13C, and terrestrial plant fatty acid markers. Low C:N ratios and high relative levels of odd-numbered carbon and branched-chained fatty acids (bacterial fatty acid markers) indicated that bacteria were an important contributor to organic matter at stations near the river and on the Mackenzie shelf. Fatty acid analysis allowed detection of a phytoplankton sinking event in the Amundsen Gulf in which polyunsaturated fatty acid (PUFA) levels in near-bottom waters significantly increased from June to July. However, this change in PUFA was not associated with any observed temporal change in chlorophyll a, δ 13C, or C:N ratios. These results show that a multiple biomarker approach is necessary in ecosystem studies of dynamic environments such as near-bottom waters or river-influenced shelves.

  12. Active seafloor gas vents on the Shelf and upper Slope in Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Hughes Clarke, J. E.; Blasco, S.; Taylor, A. E.; Melling, H.; Vagle, S.; Conway, K.; Riedel, M.; Lundsten, E.; Gwiazda, R.

    2012-12-01

    In the Canadian Arctic shelf and upper slope, a thermal disturbance caused by sea level rise at the end of the last glacial period, is still propagating into the subsurface and heating shelf sediments, where submerged terrestrial permafrost and gas hydrate, and marine gas hydrate are believed to occur in close proximity. On-going studies show evidence of gas venting in association with three distinct environments: Pingo-Like-Features (PLF) on the mid-shelf; along the shelf edge near the 100m contour; and ~1 km wide circular topographic features on the upper continental slope. Observations with a Remotely Operated Vehicle (ROV) show that methane is venting vigorously over point sources on the PLF's on the mid-shelf, and diffusely along the shelf edge. The stable isotopic composition of methane emanating from these environments indicates a microbial origin for the venting gas. Their negligible radiocarbon content indicates a geological source, as opposed to methangenisis associated with modern sediments. This is consistent with the change in the thermal regime produced by the last transgression. During glacial periods lower sea level exposed the current shelf to frigid sub-aerial temperatures. As a result, some areas of the shelf are underlain by >600m of ice-bonded permafrost with the base of methane hydrate stability at >1000m depths. The marine transgression imposed a change in mean annual surface temperature from -15°C or lower, to mean annual sea bottom temperatures near 0°C. The thermal disturbance is still propagating into the subsurface, stimulating the decomposition of both terrestrial permafrost and gas hydrate at depth and liberating methane. The PLF vents are believed to be sourced from the top of the gas hydrate stability field, while the gas emanating along the shelf edge can be from the decomposition of gas trapped in the permafrost or gas-hydrate underneath the continental shelf. The occurrence of water column flares over the distinctive circular

  13. High rates of bedload transport measured from infilling rate of large strudelscour craters in the Beaufort Sea, Alaska

    USGS Publications Warehouse

    Reimnitz, Erk; Kempema, E.W.

    1982-01-01

    Strudel scours are craters as much as 20 m wide and 4 m deep, that are excavated by vertical drainage flow during the yearly spring flooding of vast reaches of fast ice surrounding arctic deltas; they form at a rate of about 2.5 km^-2 yr^-1. Monitoring two such craters in the Beaufort Sea, we found that in relatively unprotected sites they fill in by deposition from bedload in 2 to 3 years. Net westward sediment transport results in sand layers dipping at the angle of repose westward into the strudel-scour crater, whereas the west wall of the crater remains steep to vertical. Initially the crater traps almost all bedload: sand, pebbles, and organic detritus; as infilling progresses, the materials are increasingly winnowed, and bypassing must occur. Over a 20-m-wide sector, an exposed strudel scour trapped 360 m3 of bedload during two seasons; this infilling represents a bedload transport rate of 9 m3 yr^-1 m^-1. This rate should be applicable to a 4.5-km-wide zone with equal exposure and similar or shallower depth. Within this zone, the transport rate is 40,500 m3 yr^-1, similar to estimated longshore transport rates on local barrier beaches. On the basis of the established rate of cut and fill, all the delta-front deposits should consist of strudel-scour fill. Vibracores typically show dipping interbedded sand and lenses of organic material draped over very steep erosional contacts, and an absence of horizontal continuity of strata--criteria that should uniquely identify high-latitude deltaic deposits. Given a 2- to 3-year lifespan, most strudel scours seen in surveys must be old. The same holds true for ice gouges and other depressions not adjusted to summer waves and currents, although these features record events of only the past few years. In view of such high rates of bottom reworking of the shallow shelf, any human activities creating turbidity, such as dredging, would have little effect on the environment. However, huge amounts of transitory material

  14. Distribution, abundance and behavior of endangered whales in the Alaskan Chukchi and Western Beaufort Seas, 1991: With a review 1982-91. Final report, September-November 1991

    SciTech Connect

    Moore, S.E.; Clarke, J.T.

    1992-09-01

    The report summarizes the 1991 investigations of the distribution, abundance, migration timing and route, behavior, and habitat relationships of endangered whales in the Alaskan Chukchi and western Beaufort seas (hereafter, study area); 1991 was the third year of a three year (1989-91) study. Data were collected during transect and search surveys flown in a specially modified Grumman Goose (model G21G) aircraft over the study area from 20 September through 7 November. The Bering Sea stock of bowhead whales (Balaena mysticetus) was the principal species studied. Gray whales (Eschrichtius robustus) were also studied, with incidental sightings of all other marine mammals routinely recorded. Data collected during the 1991 study were subsequently integrated with the results of surveys conducted from 1982-1990. In 1991, there were 27 sightings of 32 bowhead whales and 20 sightings of 26 gray whales in the study area from 20 September through October.

  15. A 50 % increase in the mass of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Devred, E.; Babin, M.

    2015-06-01

    Global warming has a significant impact on the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitation along the drainage basins of Arctic rivers. It has also directly impacted land and seawater temperatures with the consequence of melting permafrost and sea ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which has been sequestered in a frozen state since the Last Glacial Maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean color satellite data and field observations collected in 2009 to estimate the mass of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period, the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

  16. Ice erosion of a sea-floor knickpoint at the inner edge of the stamukhi zone, Beaufort Sea, Alaska

    USGS Publications Warehouse

    Barnes, P.W.; Asbury, J.L.; Rearic, D.M.; Ross, C.R.

    1987-01-01

    In 1981 and 1982, detailed bathymetric and side-scan sonar surveys were made of an area of the sea floor north of Prudhoe Bay, Alaska, to study the changing characteristics of the seabed at the inner boundary of the stamukhi zone, the coast-parallel zone of grounded ice ridges that occurs in water depths between 15 and 50 m in the arctic. The fathograms and sonographs resolved 10-cm features and electronic navigation gave relocations accurate to about 10 m. Year after year an ice boundary develops at the inner edge of the stamukhi zone where major shear and pressure deformation occur in about the same location. Associated with this ice boundary, the bathymetry shows a pronounced break in slope - the knickpoint - on the shelf profile at about 20 m depth. The 2-3 m-high knickpoint is cut in a consolidated gravelly mud of pre-Holocene age. A well-defined gravel and cobble shoal a few meters high usually occurs at the inshore edge of the knickpoint. The sonograph mosaic shows that seaward of the knickpoint, ice gouges saturate the sea floor and are well defined; inshore the gouges are fewer in number and are poorly defined on the records. Few gouges can be traced from the seaward side of the knickpoint across the shoals to the inshore side of the knickpoint. Studies of ice gouging rates in two seabed corridors that cross the stamukhi zone reveal the highest rates of gouging seaward of the knickpoint. We believe that the knickpoint results from ice erosion at the inner boundary of the stamukhi zone. Intensified currents associated with this boundary winnow away fine sediments. Ice bulldozing and currents shape the shoals, which perch atop the knickpoint. The knickpoint helps to limit ice forces on the seabed inshore of the stamukhi zone. ?? 1987.

  17. Synoptic evaluation of carbon cycling in Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2013-10-01

    The accelerated decline in Arctic sea ice combined with an ongoing trend toward a more dynamic atmosphere is modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of identifying indices of ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. The mean atmospheric forcing was a mild upwelling-favorable wind (~5 km h-1) blowing from the N-E and a decaying ice cover (<80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2 with a mean uptake rate of -2.0 ± 3.3 mmol C m-2d-1. We attribute this discrepancy to: (1) elevated PP rates (>600 mg C m-2d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (>10mmol C m-2d-1). Although generally <100 mg C m-2d-1, daily PP rates cumulated to a total PP of ~437.6 × 103 t C, which was roughly twice higher than the organic carbon delivery by river inputs (~241.2 × 103 t C). Subsurface PP represented 37.4% of total PP for the

  18. Bowhead whales in the Beaufort Sea: a summary of their seasonal distribution and activities, and potential disturbance by offshore oil and gas exploration and development

    SciTech Connect

    Fraker, M.A.; Richardson, W.J.

    1980-10-01

    A literature review was conducted to determine the status of information (as of 1980) on bowhead whale (Balaena mysticetus) behavior, potential sources of industrial disturbance during offshore oil and gas exploration and development, responses of bowheads to such disturbances and to identify data gaps. Approximately 102 references were reviewed in order to meet the goals of the literature summary. The spring and fall migration is described in terms of timing and distribution in the Bering, Chukchi and Beaufort Seas. Individual sources of potential disturbance to bowheads due to offshore oil industry activities are described. A general discussion of the response of cetaceans to marine traffic, stationary marine industrial activities and effluents/discharges is presented.

  19. Observations on the behavior of bowhead whales (Balaena mysticetus) in the presence of operating seismic exploration vessels in the Alaskan Beaufort Sea

    SciTech Connect

    Ljungblad, D.K.; Wuersig, B.; Swartz, S.L.; Keene, J.M.

    1985-10-01

    The response of bowhead whales to active geophysical vessels was observed during the course of 4 field experiments conducted in the Alaskan Beaufort Sea, September 1984. Conspicuous short-term behavioral changes were observed when active vessels approached to within 10km of bowheads, with the strongest responses occurring when whales were within 5km of active vessels. Behavioral responses included shorter surfacing and dive times, fewer blows per surfacing, and longer blow intervals. Total avoidance responses occured at vessel distances of 1.25km, 7.2km, 3.5km and 3.5km with associated measured sound levels from the seismic airgun arrays of 152dB, 164dB, 178dB and 163dB, respectively.

  20. Beaufort Sea monitoring program: analysis of trace metals and hydrocarbons from Outer Continental Shelf (OCS) activities. Final report, 1983-1986

    SciTech Connect

    Boehm, P.D.; Crecelius, E.; Steinhauer, W.; Steinhauer, M.; Tuckfield, C.

    1986-08-13

    An environmental-monitoring program, designed to detect and quantify long-term changes in sediment and tissue concentrations of metals and hydrocarbons potentially due to oil and gas exploration and development on the U.S. Beaufort Sea continental shelf, was initiated in 1984. In Year-1 of the three-year study, a series of benthic stations was established in the nearshore area between Barter Island and Cape Halkett. In Year-2 of the study, areal coverage of the Study Area was increased to 39 marine stations and 10 shoreline and river stations. Analysis of six replicate sediment samples for trace metals, and saturated and aromatic hydrocarbons revealed a wide range of concentrations. Both trace metal and hydrocarbon analyses of bivalve and crustacean tissues indicated concentrations differences between species but no apparent relationship between animal body burdens and sediment concentrations.

  1. Synoptic evaluation of carbon cycling in the Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2014-05-01

    The accelerated decline in Arctic sea ice and an ongoing trend toward more energetic atmospheric and oceanic forcings are modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in the southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of documenting the ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. During the field campaign, the mean wind field was a mild upwelling-favorable wind (~ 5 km h-1) from the NE. A decaying ice cover (< 80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2, with an uptake rate of -2.0 ± 3.3 mmol C m-2 d-1 (mean ± standard deviation associated with spatial variability). We attribute this discrepancy to (1) elevated PP rates (> 600 mg C m-2 d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (> 10 mmol C m-2 d-1). Daily PP rates were generally < 100 mg C m-2 d-1 and cumulated to a total PP of ~ 437.6 × 103 t C for the region over a 35-day period. This amount was about twice the

  2. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J. F.

    2013-04-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean, with a particular focus on free-living (FL) vs. particle-attached (PA) communities. Capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Pyrosequencing of 16S rRNA genes from selected samples confirmed significant differences between river, coastal and sea samples. The PA fraction was only different (15.7% similarity) from the FL one in the open sea sample. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, for the coast and river samples and both PA and FL fractions, Betaproteobacteria, Alphaproteobacteria and Actinobacteria were dominant. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also

  3. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J.-F.

    2012-12-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea, Canadian Arctic Ocean, with a particular focus on free-living vs. particle-attached communities. Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between particle-attached (PA) and free-living (FL) bacterial communities in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (proxy of DOC and CDOM), suspended particles, amino acids and chlorophyll a. 16S rRNA genes pyrosequencing of selected samples confirmed these significant differences from river to sea and also between PA and FL fractions only in open sea samples, and PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, the coast and river samples, both PA and FL fractions, were dominated by Betaproteobacteria, Alphaproteobacteria and Actinobacteria. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a~basis to predict further changes in bacterial communities should climate change lead to further

  4. Trophic interactions in the benthic boundary layer of the Beaufort Sea shelf, Arctic Ocean: Combining bulk stable isotope and fatty acid signatures

    NASA Astrophysics Data System (ADS)

    Connelly, Tara L.; Deibel, Don; Parrish, Christopher C.

    2014-01-01

    The food web structure and diets of 26 taxa of benthic boundary layer (BBL) zooplankton on the Beaufort Sea shelf were studied using carbon and nitrogen stable isotopes and fatty acids. Mean δ15N values ranged from 7.3‰ for the amphipod Melita formosa to 14.9‰ for an unidentified polychaete, suggesting that taxa sampled came from three trophic levels. For 8 taxa, the lightest carbon signature occurred near the mouth of the Mackenzie River. Stable isotope ratios helped clarify the origin of signature fatty acids. Levels of certain polyunsaturated fatty acids (PUFA) were negatively correlated with δ15N, with the exception of 22:6ω3, which was positively correlated with δ15N, suggesting that this essential PUFA was retained through the food web. Discriminant analysis proved to be a powerful tool, predicting taxa from fatty acid profiles with 99% accuracy, and revealing strong phylogenetic trends in fatty acid profiles. The amphipod Arrhis phyllonyx had higher levels of ω6 PUFA, especially 20:4ω6 with several possible sources, than other peracarid crustaceans. The holothurian had high levels of odd numbered and branched chain fatty acids, indicative of bacterial consumption, while fatty acids of phytoplankton origin were important discriminants for Calanus hyperboreus and the chaetognaths Eukrohnia hamata and Parasagitta elegans. This relationship indicates that the conventional phytoplankton-copepod-chaetognath food web found in the water column also exists in the BBL. This observation, as well as generally low δ15N and high levels of certain PUFA in samples with lower δ15N, strongly suggests that BBL zooplankton on the Beaufort Sea shelf have access to fresh material of phytoplankton origin either by feeding on sedimenting matter or by active migration to surface waters.

  5. The relationship between sea ice concentration and the spatio-temporal distribution of vocalizing bearded seals (Erignathus barbatus) in the Bering, Chukchi, and Beaufort Seas from 2008 to 2011

    NASA Astrophysics Data System (ADS)

    MacIntyre, Kalyn Q.; Stafford, Kathleen M.; Conn, Paul B.; Laidre, Kristin L.; Boveng, Peter L.

    2015-08-01

    Bearded seals (Erignathus barbatus) are widely distributed in the Arctic and sub-Arctic; the Beringia population is found throughout the Bering, Chukchi and Beaufort Seas (BCB). Bearded seals are highly vocal, using underwater calls to advertise their breeding condition and maintain aquatic territories. They are also closely associated with pack ice for reproductive activities, molting, and resting. Sea ice habitat for this species varies spatially and temporally throughout the year due to differences in underlying physical and oceanographic features across its range. To test the hypothesis that the vocal activity of bearded seals is related to variations in sea ice, passive acoustic data were collected from nine locations throughout the BCB from 2008 to 2011. Recording instruments sampled on varying duty cycles ranging from 20% to 100% of each hour, and recorded frequencies up to 8192 Hz. Spectrograms of acoustic data were analyzed manually to calculate the daily proportion of hours with bearded seal calls at each sampling location, and these call activity proportions were correlated with daily satellite-derived estimates of sea ice concentration. Bearded seals were vocally active nearly year-round in the Beaufort and Chukchi Seas with peak activity occurring from mid-March to late June during the mating season. The duration of call activity in the Bering Sea was shorter, lasting typically only five months, and peaked from mid-March to May at the northernmost recorders. In all areas, call activity was significantly correlated with higher sea ice concentrations (p < 0.01). These results suggest that losses in ice cover may negatively impact bearded seals, not just by loss of habitat but also by altering the behavioral ecology of the BCB population.

  6. Seasonal and regional patterns in egg production of Calanus glacialis/marshallae in the Chukchi and Beaufort Seas during spring and summer, 2002

    NASA Astrophysics Data System (ADS)

    Plourde, Stéphane; Campbell, Robert G.; Ashjian, Carin J.; Stockwell, Dean A.

    2005-12-01

    Understanding the physical and biogeochemical processes that control the exchange of biogenic carbon within and between the arctic shelves, slopes, and deep basins is a key objective of the Western Arctic Shelf-Basin Interaction program (SBI). Here, egg production (EP) of the dominant copepod Calanus glacialis/marshallae was used as an indicator of food limitation for the mesozooplankton community in the Chukchi and Beaufort Seas in spring and summer, 2002. Both C. glacialis and C. marshallae may occur in this region but the two cannot easily be differentiated visually. Four oceanographic regions were objectively identified that roughly corresponded to the different pathways in circulation of nutrient-rich Pacific water. A 'transition' region characterized by 'older' Pacific water was located at the shelfbreak and separated the nutrient-rich shelf water and the low-nutrient waters of the deep basin. The observed spatial pattern in EP in C. glacialis/marshallae in spring and summer resulted both from the different water mass environments and from the reproductive cycle of the species. EP was greater on the shelf than in the basin, corresponding to differences in body size and nitrogen condition factor (NCF) in females, while the egg viability was generally high throughout the study area. EP showed no relationship with low-chlorophyll a biomass under heavy ice-cover in spring, while a significant relationship was observed in the more open water in summer. Adult female carbon condition factor (CCF) was much higher in summer, reflecting the accumulation of lipids during the growth season. Small animals with a markedly greater NCF dominated on the shelf. The shelfbreak region contained a mixture of females from the shelf and the basin with intermediate sizes, conditions, and EP rates. The occurrence of water typical of the 'transition' shelfbreak region and elevated EP in C. glacialis/marshallae offshore on the Barrow Canyon and East Barrow sections indicated offshore

  7. Long-term changes of mercury levels in ringed seal (Phoca hispida) from Amundsen Gulf, and beluga (Delphinapterus leucas) from the Beaufort Sea, western Canadian Arctic.

    PubMed

    Outridge, P M; Hobson, K A; Savelle, J

    2009-11-15

    Mercury (Hg) concentrations were determined in the canine teeth of ringed seals (Phoca hispida) harvested during the 13th-14th, late 19th and early 21st Centuries in Amundsen Gulf, Northwest Territories, Canada. Most historical and pre-industrial teeth contained undetectable Hg levels (i.e. <1.0 ng/g DW), whereas samples from 2001-03 contained up to 12 ng/g DW in an age-dependent pattern. Assuming a median [Hg] value in 13th-14th Century teeth of half the detection limit (i.e. 0.5 ng/g DW), geometric means of Hg in modern teeth were 9-17 times those of seals in the 14th Century, equivalent to an anthropogenic input of 89-94% of total Hg in modern seals. These results corroborate a previous study of beluga (Delphinapterus leucas) in the nearby Beaufort Sea. While the seals' trophic position (inferred from delta(15)N values) did not change over time, modern delta(13)C values were lower by about 2 per thousand than in the 14th and 19th Centuries. This could be due to increased dissolution of anthropogenically derived CO(2) in the ocean from the atmosphere, but could also indicate more offshore pelagic feeding by modern seals, which might be a factor in their Hg exposure. New tooth [Hg] data are also presented for the Beaufort Sea beluga, using recently-discovered museum samples collected in 1960/61, which showed that most of the anthropogenic contribution to beluga Hg had already taken effect by 1960 (reaching approximately 75% of total Hg). Taken together, the long-term seal and beluga data indicate that whereas Hg levels in the marine ecosystems of the western Canadian Arctic were probably unchanged from pre-industrial times up to the late 19th Century, there was a significant, many-fold increase in the early to mid-20th Century, but little or no change after about the early 1960s.

  8. An evaluation of the science needs to inform decisions on Outer Continental Shelf energy development in the Chukchi and Beaufort Seas, Alaska

    USGS Publications Warehouse

    Holland-Bartels, Leslie; Pierce, Brenda

    2011-01-01

    On March 31, 2010, Secretary of the Interior Ken Salazar announced a national strategy for Outer Continental Shelf (OCS) oil and gas development. In that announcement, the Administration outlined a three-pronged approach (U.S. Department of the Interior, 2010a): Development: "...expand development and production throughout the Gulf of Mexico, including resource-rich areas of the Eastern Gulf of Mexico..." Exploration: "...expand oil and gas exploration in frontier areas, such as the Arctic Ocean and areas in the Atlantic Ocean, to gather the information necessary to develop resources in the right places and the right ways." Conservation: "...calls for the protection of special areas like Bristol Bay in Alaska...national treasure[s] that we must protect for future generations." In a companion announcement (U.S. Department of the Interior, 2010b), within the Administration's "Exploration" component, the Secretary asked the U.S. Geological Survey (USGS) to conduct an initial, independent evaluation of the science needs that would inform the Administration's consideration of the right places and the right ways in which to develop oil and gas resources in the Arctic OCS, particularly focused on the Beaufort and Chukchi Seas (fig. 1).

  9. Direct Observations of Heat and Salt Entrainment Fluxes Across the Base of the Ocean Mixing Layer Under Marginal Ice Conditions in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Gallaher, S.; Stanton, T. P.; Shaw, W. J.

    2014-12-01

    Measurements of turbulent fluxes of heat and salt across the base of the upper ocean mixed layer in summer marginal ice zone conditions in the Beaufort Sea were made using two eddy-correlation flux sensors with a vertical separation of 6m mounted on a depth-controlled frame. A third flux sensor measured fluxes 2m below the ice. A 16 element thermistor string measured finescale thermal gradients while a high resolution ADCP measured current profiles every 20cm across the frame to resolve finescale shear. Every hour the frame was profiled between 2m and 60m depth then re-positioned to span the base of the active mixing layer, determined primarily from the density profile, allowing the surface mixed layer entrainment fluxes to be determined. A range of wind conditions allowed mixed layer entrainment fluxes to be compared with several bulk entrainment formulations based on surface friction velocity values and the density jump across the base of the surface mixing layer.

  10. UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    NASA Astrophysics Data System (ADS)

    Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

    2012-11-01

    Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV and PAR diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m-2 for UV-B (305 nm), UV-A (380 nm) and PAR, respectively), we report significant light penetration with 10% irradiance depths (Z10% (λ)) reaching 9.5 m for 340 nm (UV-A) radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS) and PARAFAC analysis. Our results showed an in-situ biological component (C1) that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta sector, whereas the protein-like (C3) component dominated in the saltiest waters of the North East sector.

  11. An evaluation of the science needs to inform decisions on Outer Continental Shelf energy development in the Chukchi and Beaufort Seas, Alaska

    USGS Publications Warehouse

    Holland-Bartels, Leslie; Pierce, Brenda

    2011-01-01

    The U. S. Geological Survey (USGS) was asked to conduct an initial, independent evaluation of the science needs that would inform the Administration's consideration of the right places and the right ways in which to develop oil and gas resources in the Arctic Outer Continental Shelf (OCS), particularly focused on the Beaufort and Chukchi Seas. Oil and gas potential is significant in Arctic Alaska. Beyond petroleum potential, this region supports unique fish and wildlife resources and ecosystems, and indigenous people who rely on these resources for subsistence. This report summarizes key existing scientific information and provides initial guidance of what new and (or) continued research could inform decision making. This report is presented in a series of topical chapters and various appendixes each written by a subset of the USGS OCS Team based on their areas of expertise. Three chapters (Chapters 2, 3, and 4) provide foundational information on geology; ecology and subsistence; and climate settings important to understanding the conditions pertinent to development in the Arctic OCS. These chapters are followed by three chapters that examine the scientific understanding, science gaps, and science sufficiency questions regarding oil-spill risk, response, and impact (Chapter 5), marine mammals and anthropogenic noise (Chapter 6), and cumulative impacts (Chapter 7). Lessons learned from the 1989 Exxon Valdez Oil Spill are included to identify valuable "pre-positioned" science and scientific approaches to improved response and reduced uncertainty in damage assessment and restoration efforts (appendix D). An appendix on Structured Decision Making (appendix C) is included to illustrate the value of such tools that go beyond, but incorporate, science in looking at what can/should be done about policy and implementation of Arctic development. The report provides a series of findings and recommendations for consideration developed during the independent examination of

  12. Distribution, Abundance, Behavior, and Bioacoustics of Endangered Whales in the Western Beaufort and Northeastern Chukchi Seas, 1979-87

    DTIC Science & Technology

    1988-07-01

    water lead systems that annually develop relatively nearshore in the Chukchi Sea , but offshore and well north of oil exploration activities in...seen in September. Walrus were most often seen swimming in open water and resting in light ice (0-30%; 40%, n = 883) or hauled out in heavy ice (36...little broken floe ice was available to haul out on and the ice edge was far to the north (see figure 21). Overall,

  13. Megafauna recovered from a cold hydrocarbon seep in the deep Alaskan Beaufort Sea, including a new species of Axinus (Thracidae: Bivalvia: Mollusca)

    NASA Astrophysics Data System (ADS)

    Powell, C. L.; Valentich-Scott, P.; Lorenson, T. D.; Edwards, B. D.

    2011-12-01

    Several specimens of a new species of Axinus and a single well-worn gastropod columella provisionally assigned to the genus Neptunea (Buccinidae: Gastropoda: Mollusca) were recently recovered from at least two cores, the longest of which is 5.72 m long, from a large seafloor mound, informally named the Canning Seafloor Mound (CSM). The CSM is located at 2,530 m water depth on the Alaskan Beaufort Sea slope north of Camden Bay and is a fluid explosion feature containing methane hydrate and methane-saturated sediments overlying a folded and faulted deep basin. Only two modern species of Axinus are currently known. Axinus grandis (Verrill & Smith, 1885) is a northern Atlantic species and the recently described species, A. cascadiensis Oliver and Holmes (2007), is only known from Baby Bare Seamount, Cascadia Basin, northeastern Pacific Ocean. Common fragments, single valves, and a single articulated specimen represent this new Axinus species. These shells were distributed over nearly the entire length of the primary core. All specimens show wear and (or) dissolution. The age of these specimens is unknown and no living representatives were encountered. The genus Axinus has a fossil record back to the early Eocene in England and the Paleocene and Eocene in Egypt. Biogeographically the genus appears to have originated in the Tethys Sea and became established in the Atlantic Ocean during the Eocene, spreading across the Arctic Ocean in the late Tertiary. With the opening of the Bering Strait in the latest Miocene or early Pliocene the genus Axinus migrated southwest into the northeast Pacific. Interestingly, hydrocarbon seep deposits are also present on the adjacent North Slope of Alaska in the Marsh Anticline at Carter Creek, Camden Bay. These rocks, the Nuwok beds, contain abundant Thracidae bivalve of the genus Thracia, but not Axinus, however the rocks also represent cold seep deposits. These rocks have been variously dated from Oligocene to Pliocene and the exact age

  14. Behavior, disturbance responses, and feeding of bowhead whales Balaena mysticetus in the Beaufort Sea, 1980-1981

    SciTech Connect

    Richardson, W.J.; Buchanan, R.A.; Clark, C.W.; Dorsey, E.M.; Fraker, M.A.

    1982-08-01

    In August and September of 1981, the second year, of a five-year study of bowhead whales was completed in the Canadian Beauford Sea. The purpose of the project was to (1) document the normal behavior of bowheads; (2) describe the characteristics of waterborne noise resulting from offshore oil industry activities; (3) quantify the behavioral responses of bowheads to various offshore oil-industry activities, and (4) characterize bowhead feeding areas. Field activities were based in Tuktoyoktuk N.W.T. and were carried out from aircraft, boats, and shore camps.

  15. Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-A

    NASA Technical Reports Server (NTRS)

    Reimnitz, E. (Principal Investigator); Barnes, P. W.; Toimil, L. J.; Harden, D.

    1976-01-01

    The author has identified the following significant results. Shearing periodically occurs between the westward moving pack ice (3 to 10 km/d) within the Pacific Gyre and the fast ice along the coast, forming major grounded shear and pressure ridges between the 10 to 40 m isobaths. Ridges occur in patterns conforming to known shoals. The zone of grounded ridges, called stamukhi zone, protects the inner shelf and coast from marine energy and pack ice forces. Relatively undeformed fast ice grows inshore of the stamukhi zone. The boundary is explained in terms of pack ice drift and major promontories and shoals. Intense ice gaging, highly disrupted sediments, and landward migration of shoals suggest that much of the available marine energy is expended on the sea floor within the stamukhi zone. Naleds (products of river icings) on the North Slope are more abundant east than west of the Colville River. Their location, growth, and decay were studied from LANDSAT imagery.

  16. Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

    NASA Astrophysics Data System (ADS)

    Forest, A.; Babin, M.; Stemmann, L.; Picheral, M.; Sampei, M.; Fortier, L.; Gratton, Y.; Bélanger, S.; Devred, E.; Sahlin, J.; Doxaran, D.; Joux, F.; Ortega-Retuerta, E.; Jeffrey, W. H.; Martín, J.; Gasser, B.; Miquel, J. C.

    2012-08-01

    .26) and the high contribution (~94 %) of fast-sinking small aggregates (<1 mm; 20-30 m d-1) to the mass fluxes suggested that settling material across the region was overall fluffy, porous, and likely resulting from the aggregation of marine detritus, gel-like substances and ballast minerals. Our study demonstrates that vertical POC fluxes in Arctic shelf systems are spatially complex, sensitive to environmental forcings, and determined by both physicochemical mechanisms and food web functioning. In conclusion, we hypothesize that the incorporation of terrestrial matter into the Beaufort Sea food web could be catalyzed by bacteria via the incorporation of dissolved terrestrial carbon liberated through the photo-cleavage and/or hydrolysis of land-derived POC interweaved with marine aggregates.

  17. Apparent optical properties of the Canadian Beaufort Sea - Part 2: The 1% and 1 cm perspective in deriving and validating AOP data products

    NASA Astrophysics Data System (ADS)

    Hooker, S. B.; Morrow, J. H.; Matsuoka, A.

    2013-07-01

    A next-generation in-water profiler designed to measure the apparent optical properties (AOPs) of seawater was developed and validated across a wide dynamic range of in-water properties. The new free-falling instrument, the Compact-Optical Profiling System (C-OPS), was based on sensors built with a cluster of 19 state-of-the-art microradiometers spanning 320-780 nm and a novel kite-shaped backplane. The new backplane includes tunable ballast, a hydrobaric buoyancy chamber, plus pitch and roll adjustments, to provide unprecedented stability and vertical resolution in near-surface waters. A unique data set was collected as part of the development activity plus the first major field campaign that used the new instrument, the Malina expedition to the Beaufort Sea in the vicinity of the Mackenzie River outflow. The data were of sufficient resolution and quality to show that errors - more correctly, uncertainties - in the execution of data sampling protocols were measurable at the 1% and 1 cm level with C-OPS. A theoretical sensitivity analysis as a function of three water types established by the peak in the remote sensing reflectance spectrum, Rrs(λ), revealed which water types and which parts of the spectrum were the most sensitive to data acquisition uncertainties. Shallow riverine waters were the most sensitive water type, and the ultraviolet and near-infrared spectral end members, which are critical to next-generation satellite missions, were the most sensitive parts of the spectrum. The sensitivity analysis also showed how the use of data products based on band ratios significantly mitigated the influence of data acquisition uncertainties. The unprecedented vertical resolution provided high-quality data products, which supported an alternative classification capability based on the spectral diffuse attenuation coefficient, Kd(λ). The Kd(320) and Kd(780) data showed how complex coastal systems can be distinguished two-dimensionally and how near-ice water masses

  18. Atlas of the Beaufort Sea.

    DTIC Science & Technology

    1984-10-01

    Groton, CT 06340 13 . Type of Reoort and Period Covereo12. Soonsoring Agency Name and Address Department of Transportation • U.S. Coast Guard FINAL REPORT...A- 13 4.1 Outer Shelf . .. . . . . . . . . . . . . . . . . . . . . . . A- 13 4.2 Inner Shelf...A- 13 5. LAGOON AND NEARSHORE CIRCULATION...... . . . . . . . . . . . A-24 5.1 Open Lagoons

  19. Composition, biomass and energetic content of biota in the vicinity of feeding bowhead whales (Balaena mysticetus) in the Cape Bathurst upwelling region (south eastern Beaufort Sea)

    NASA Astrophysics Data System (ADS)

    Walkusz, Wojciech; Williams, William J.; Harwood, Lois A.; Moore, Sue E.; Stewart, Barbara E.; Kwasniewski, Slawomir

    2012-11-01

    Bowhead whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort population form annual late-summer feeding aggregations offshore of the eastern Tuktoyaktuk Peninsula and Cape Bathurst. This region is strongly influenced by episodic upwelling events. A systematic aerial survey (10% coverage) was flown over the eastern shelf on 2 August 2008, revealing large numbers of bowheads (est. 3500 individuals) in a clumped distribution over the continental shelf. Between 7 and 11 August 2008, zooplankton samples and hydrography were obtained from the vicinity of two bowhead feeding aggregations, one at the northeast edge of the continental shelf, and the second off the northeast shore of the Cape Bathurst. Dense aggregations of zooplankton were found in the lower part of the water column (below 40 m), on the shelf, in water with an upwelling signature. The zooplankton were largely resting phases of calanoid copepods (Calanus hyperboreus and C. glacialis) and collectively had twice the abundance, twice the biomass, three times the caloric density and thus six times the energy content of contemporaneous zooplankton samples from the western Canadian Beaufort Shelf. Although upwelling at Cape Bathurst is wind-driven and thus episodic in nature, its consistent delivery of zooplankton to the bowhead foraging area creates conditions attractive to bowhead whales, with an estimated 33% of the bowhead population present on the eastern portion of the shelf at the time of the August 2008 aerial survey.

  20. 76 FR 49664 - Drawbridge Operation Regulation; Beaufort Channel, Beaufort, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-11

    ... Triathlon''. This deviation allows the bridge to remain in the closed position during the race to ensure the..., at Beaufort, NC. The bike route of the ``Neuse Riverkeeper Foundation Sprint Triathlon'' crosses...

  1. 76 FR 78820 - Safety Zone; City of Beaufort's Tricentennial New Year's Eve Fireworks Display, Beaufort River...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-20

    ... Eve Fireworks Display, Beaufort River, Beaufort, SC AGENCY: Coast Guard, DHS. ACTION: Temporary final... Beaufort, South Carolina, during the City of Beaufort's Tricentennial New Year's Eve Fireworks Display. The... navigable waters of the United States. Discussion of Rule On New Year's Eve, a fireworks display will...

  2. The Legacy of Admiral Beaufort

    ERIC Educational Resources Information Center

    Heidorn, Keith

    1978-01-01

    Francis Beaufort was a British naval officer who developed a wind force scale based on the effect of wind strength on frigate sails. Over the years, this scale has been modified, and today it is used internationally to describe the speed of the wind using numerical equivalents. (MA)

  3. MIZMAS: Modeling the Evolution of Ice Thickness and Floe Size Distributions in the Marginal Ice Zone of the Chukchi and Beaufort Seas

    DTIC Science & Technology

    2014-09-30

    physics to represent changes in FSD due to ice advection, thermodynamic growth or decay, lateral melting , ridging and rafting, and wave-induced...forecast. (4) Explore the impacts of future anthropogenic global climate change (including a summer arctic ice -free regime) on the CBS MIZ processes...the Pan- arctic Ice /Ocean Modeling and Assimilation System (PIOMAS), a variant of MIZMAS, to study changes in the Arctic sea ice and ocean system

  4. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2013-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Atmospheric Profiles, Clouds , and the Evolution of Sea Ice...sea ice retreats further, changes in lower atmospheric temperature, humidity, winds, and clouds are likely to result from changed sea ice...how changes in sea ice and sea surface conditions in the SIZ affect changes in cloud properties and cover. • Determine the role additional atmospheric

  5. Aerial Surveys of Endangered Whales in the Northern Bering, Eastern Chukchi, and Alaskan Beaufort Seas, 1985: With a Seven Year Review, 1979-85.

    DTIC Science & Technology

    1986-08-01

    8217 . " - • " " " ’ " ’"" . - - - " "" "° " " "" " " , , - " UUSS USSRA as LEGENDJ 0GV S CAPE PRINCE OF WALES % .4(DO crnM BERING SEA OCG 00 M 0a hI)rO 0 0 0 1 Kp 000...o,,o_.._ .- Demarcation Pt Cape Lisbuneo 680I , ialn 680: 660 USSR16 100 15 1 apatocni Prince of Wales AndSK i nest coe s dNo o i 64...and migration patterns of the white whale ( Beluga ), Delphinapterus leucas. Rep. int. Whal. Commn. vol. 30:465-480. 1980. Herzing, D.L. and B.R. Mate

  6. Formation and ridging of flaw leads in the eastern Canadian Beaufort Sea. Special Session C06 on: “Physical, biological and biogeochemical processes associated with young thin ice types”

    NASA Astrophysics Data System (ADS)

    Prinsenberg, S. J.

    2009-12-01

    Formation and ridging of flaw leads in the eastern Canadian Beaufort Sea. Simon Prinsenberg1 and Yves Graton2 1Bedford Inst. of Oceanography, Fisheries and Oceans Canada P.O. Box1006, Dartmouth, Nova Scotia, B2Y 4A2, Canada prinsenbergs@mar.dfo-mpo.gc.ca 2Inst. National de la Recherche Scientifique-Eau, INRS-ETE University of Quebec at Quebec City, Quebec yvesgratton@eteinrs.ca During the winter of 2008, the flaw lead south of Banks Island repeatedly opened and closed representing an elongated region where periodically the large ice growth stimulates the densification of the surface layer due to salt rejection and instigates a local circulation pattern that will affect the biological processes of the region. Helicopter-borne sensors were available to monitor the aftermath of one of the rapid closing of the flaw lead into extensive elongated rubble field using a Canadian Ice breaker, CCGS Amundsen, as a logistic base. After the wind reversed a new open flaw lead 20km wide restarting a new flaw lead formation cycle. Ice thickness and surface roughness data were collected from the rubble field and adjacent open flaw lead with an Electromagnetic-Laser system. The strong wind event of April 4-5 2009 generated a large linear 1.5km wide ice rubble field up to 8-10m thick when the 60cm thick, 18km wide flaw lead was crunched into land-fast by the 1.5m thick offshore pack ice. It is expected that during rapid ice growth in a flaw lead, salt rejection increase the density of the surface water layer producing a surface depression (Low) and cyclonic circulation. In contrast at depth, the extra surface dense water produces a high in the horizontal pressure field and anti-cyclonic circulation which remains after the rapid ice growth within the flaw lead stops. One of such remnants may have been observed during the CFL-IPY winter survey.

  7. Morbillivirus and Toxoplasma exposure and association with hematological parameters for southern Beaufort Sea polar bears: potential response to infectious agents in a sentinel species

    USGS Publications Warehouse

    Kirk, Cassandra M.; Amstrup, Steven C.; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M.

    2010-01-01

    Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear’s status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1–2 year olds least likely to be seropositive and bears aged 5–7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.

  8. Morbillivirus and Toxoplasma exposure and association with hematological parameters for southern Beaufort Sea polar bears: potential response to infectious agents in a sentinel species.

    PubMed

    Kirk, Cassandra M; Amstrup, Steven; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M

    2010-09-01

    Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear's status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1-2 year olds least likely to be seropositive and bears aged 5-7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.

  9. Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

    NASA Astrophysics Data System (ADS)

    Forest, A.; Babin, M.; Stemmann, L.; Picheral, M.; Sampei, M.; Fortier, L.; Gratton, Y.; Bélanger, S.; Devred, E.; Sahlin, J.; Doxaran, D.; Joux, F.; Ortega-Retuerta, E.; Martín, J.; Jeffrey, W. H.; Gasser, B.; Miquel, J. Carlos

    2013-05-01

    A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here we combine mooring times series, ship-based measurements and remote sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their determinants in summer. Flux data were obtained with sediment traps moored around 125 m and via a regional empirical algorithm applied to particle size distributions (17 classes from 0.08-4.2 mm) measured by an Underwater Vision Profiler 5. The low fractal dimension (i.e., porous, fluffy particles) derived from the algorithm (1.26 ± 0.34) and the dominance (~ 77%) of rapidly sinking small aggregates (< 0.5 mm) in total fluxes suggested that settling material was the product of recent aggregation processes between marine detritus, gel-like substances, and ballast minerals. Modeled settling velocity of small and large aggregates was, respectively, higher and lower than in previous studies within which a high fractal dimension (i.e., more compact particles) was consequential of deep-trap collection (~400-1300 m). Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e., principal coordinates of neighbor matrices, PCNM) were conducted to partition the variation of the 17 POC flux size classes. Flux variability was explained at 69.5% by the addition of a temporal trend, 7 significant PCNM, and 9 biophysical variables. The first PCNM canonical axis (44.5% of spatial variance) reflected the total magnitude of POC fluxes through a shelf-basin gradient controlled by bottom depth and sea ice concentration (p < 0.01). The second most important spatial structure (5.0%) corresponded to areas where shelf break upwelling is known to occur under easterlies and where phytoplankton was

  10. From Tununak to Beaufort: Taking a Critical Inquiry Stance as a First Year Teacher

    ERIC Educational Resources Information Center

    Fecho, Bob; Price, Kim; Read, Chris

    2004-01-01

    In this article, the authors show how two first year teachers a continent apart--Kim in the village of Tununak on the Bering Sea in Alaska and Chris in Beaufort, South Carolina, on the Atlantic Ocean--were able to take inquiry stances on their classrooms. In particular, through analysis of e-mails written in Chris' and Kim's first years of…

  11. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the SeasonalIce Zone Reconnaissance Surveys

    DTIC Science & Technology

    2015-09-30

    quality of sea ice drift forecasts from 6 hours to 9 days. We examined the role of wind forcing. Advanced Observation Platforms (IR Dropsonde...the continental origin of the air mass in the BCSIZ domain and the downslope warming and drying over the Brooks Range. Both S01 and S04 have much...forecast model increases the probability of tracking a target drifting in sea ice with a 10x10 km image from 60% to 95% for a 24-hr forecast and from

  12. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2015-09-30

    retreat of the SIZ. As sea ice retreats further, changes in lower atmospheric temperature, humidity, winds , and clouds are likely to result from changed...obtain atmospheric profiles of temperature, humidity, and winds from the time of ice edge retreat in spring to advance in fall. Transects following...aerial vehicles (Glidersonde, SmartSonde) designed to obtain detailed high-vertical-resolution temperature, humidity and wind profiles and cloud

  13. Marine fish community structure and habitat associations on the Canadian Beaufort shelf and slope

    NASA Astrophysics Data System (ADS)

    Majewski, Andrew R.; Atchison, Sheila; MacPhee, Shannon; Eert, Jane; Niemi, Andrea; Michel, Christine; Reist, James D.

    2017-03-01

    Marine fishes in the Canadian Beaufort Sea have complex interactions with habitats and prey, and occupy a pivotal position in the food web by transferring energy between lower- and upper-trophic levels, and also within and among habitats (e.g., benthic-pelagic coupling). The distributions, habitat associations, and community structure of most Beaufort Sea marine fishes, however, are unknown thus precluding effective regulatory management of emerging offshore industries in the region (e.g., hydrocarbon development, shipping, and fisheries). Between 2012 and 2014, Fisheries and Oceans Canada conducted the first baseline survey of offshore marine fishes, their habitats, and ecological relationships in the Canadian Beaufort Sea. Benthic trawling was conducted at 45 stations spanning 18-1001 m depths across shelf and slope habitats. Physical oceanographic variables (depth, salinity, temperature, oxygen), biological variables (benthic chlorophyll and integrated water-column chlorophyll) and sediment composition (grain size) were assessed as potential explanatory variables for fish community structure using a non-parametric statistical approach. Selected stations were re-sampled in 2013 and 2014 for a preliminary assessment of inter-annual variability in the fish community. Four distinct fish assemblages were delineated on the Canadian Beaufort Shelf and slope: 1) Nearshore-shelf: <50 m depth, 2) Offshore-shelf: >50 and ≤200 m depths, 3) Upper-slope: ≥200 and ≤500 m depths, and 4) Lower-slope: ≥500 m depths. Depth was the environmental variable that best explained fish community structure, and each species assemblage was spatially associated with distinct aspects of the vertical water mass profile. Significant differences in the fish community from east to west were not detected, and the species composition of the assemblages on the Canadian Beaufort Shelf have not changed substantially over the past decade. This community analysis provides a framework for testing

  14. Evidence of chromosomal damage in common eiders (Somateria mollissima) from the Baltic Sea.

    PubMed

    Matson, Cole W; Franson, J Christian; Hollmén, Tuula; Kilpi, Mikael; Hario, Martti; Flint, Paul L; Bickham, John W

    2004-12-01

    Common eiders nesting in the Baltic Sea are exposed to generally high levels of contaminants including potentially genotoxic polycyclic aromatic hydrocarbons and organochlorines. Blood samples were collected from eiders at eight sites in the Baltic Sea and two sites in the Beaufort Sea. DNA content variation was estimated using the flow cytometric method, and subsequently utilized as a biomarker of genetic damage. We observed no significant differences in genetic damage among populations within either the Baltic or Beaufort Seas. However, eider populations from the Baltic Sea had significantly elevated estimates of genetic damage compared to populations from the Beaufort Sea.

  15. Evidence of chromosomal damage in common eiders (Somateria mollissima) from the Baltic Sea

    USGS Publications Warehouse

    Matson, C.W.; Franson, J.C.; Hollmén, Tuula E.; Kilpi, Mikael; Hario, Martti; Flint, P.L.; Bickham, J.W.

    2004-01-01

    Common eiders nesting in the Baltic Sea are exposed to generally high levels of contaminants including potentially genotoxic polycyclic aromatic hydrocarbons and organochlorines. Blood samples were collected from eiders at eight sites in the Baltic Sea and two sites in the Beaufort Sea. DNA content variation was estimated using the flow cytometric method, and subsequently utilized as a biomarker of genetic damage. We observed no significant differences in genetic damage among populations within either the Baltic or Beaufort Seas. However, eider populations from the Baltic Sea had significantly elevated estimates of genetic damage compared to populations from the Beaufort Sea.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. 33 CFR 117.822 - Beaufort Channel, NC.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Beaufort Channel, NC. 117.822 Section 117.822 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements North Carolina § 117.822 Beaufort Channel, NC....

  18. 33 CFR 117.822 - Beaufort Channel, NC.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Beaufort Channel, NC. 117.822 Section 117.822 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements North Carolina § 117.822 Beaufort Channel, NC....

  19. Widespread gas hydrate instability on the upper U.S. Beaufort margin

    USGS Publications Warehouse

    Phrampus, Benjamin J.; Hornbach, Matthew J.; Ruppel, Carolyn D.; Hart, Patrick E.

    2014-01-01

    The most climate-sensitive methane hydrate deposits occur on upper continental slopes at depths close to the minimum pressure and maximum temperature for gas hydrate stability. At these water depths, small perturbations in intermediate ocean water temperatures can lead to gas hydrate dissociation. The Arctic Ocean has experienced more dramatic warming than lower latitudes, but observational data have not been used to study the interplay between upper slope gas hydrates and warming ocean waters. Here we use (a) legacy seismic data that constrain upper slope gas hydrate distributions on the U.S. Beaufort Sea margin, (b) Alaskan North Slope borehole data and offshore thermal gradients determined from gas hydrate stability zone thickness to infer regional heat flow, and (c) 1088 direct measurements to characterize multidecadal intermediate ocean warming in the U.S. Beaufort Sea. Combining these data with a three-dimensional thermal model shows that the observed gas hydrate stability zone is too deep by 100 to 250 m. The disparity can be partially attributed to several processes, but the most important is the reequilibration (thinning) of gas hydrates in response to significant (~0.5°C at 2σ certainty) warming of intermediate ocean temperatures over 39 years in a depth range that brackets the upper slope extent of the gas hydrate stability zone. Even in the absence of additional ocean warming, 0.44 to 2.2 Gt of methane could be released from reequilibrating gas hydrates into the sediments underlying an area of ~5–7.5 × 103 km2 on the U.S. Beaufort Sea upper slope during the next century.

  20. Widespread gas hydrate instability on the upper U.S. Beaufort margin

    NASA Astrophysics Data System (ADS)

    Phrampus, Benjamin J.; Hornbach, Matthew J.; Ruppel, Carolyn D.; Hart, Patrick E.

    2014-12-01

    The most climate-sensitive methane hydrate deposits occur on upper continental slopes at depths close to the minimum pressure and maximum temperature for gas hydrate stability. At these water depths, small perturbations in intermediate ocean water temperatures can lead to gas hydrate dissociation. The Arctic Ocean has experienced more dramatic warming than lower latitudes, but observational data have not been used to study the interplay between upper slope gas hydrates and warming ocean waters. Here we use (a) legacy seismic data that constrain upper slope gas hydrate distributions on the U.S. Beaufort Sea margin, (b) Alaskan North Slope borehole data and offshore thermal gradients determined from gas hydrate stability zone thickness to infer regional heat flow, and (c) 1088 direct measurements to characterize multidecadal intermediate ocean warming in the U.S. Beaufort Sea. Combining these data with a three-dimensional thermal model shows that the observed gas hydrate stability zone is too deep by 100 to 250 m. The disparity can be partially attributed to several processes, but the most important is the reequilibration (thinning) of gas hydrates in response to significant (~0.5°C at 2σ certainty) warming of intermediate ocean temperatures over 39 years in a depth range that brackets the upper slope extent of the gas hydrate stability zone. Even in the absence of additional ocean warming, 0.44 to 2.2 Gt of methane could be released from reequilibrating gas hydrates into the sediments underlying an area of ~5-7.5 × 103 km2 on the U.S. Beaufort Sea upper slope during the next century.

  1. A Business Case Analysis on the Feasibility of Recapturing Inpatient Obstetrical Services for Naval Hospital Beaufort

    DTIC Science & Technology

    2006-06-14

    its impact on surrounding health care facilities, to include Naval Hospital Beaufort. The National Defense Authorization Act for fiscal year 2002...will be examined along with its impact on TRICARE Obstetrical in-patient beneficiaries and their available choices. The author will examine the...Facility (MTF), it services and treats the eligible population surrounding Beaufort County, Beaufort, SC. Naval Hospital Beaufort is fully accredited by

  2. Sea Ice and Oceanographic Conditions.

    ERIC Educational Resources Information Center

    Oceanus, 1986

    1986-01-01

    The coastal waters of the Beaufort Sea are covered with ice three-fourths of the year. These waters (during winter) are discussed by considering: consolidation of coastal ice; under-ice water; brine circulation; biological energy; life under the ice (including kelp and larger animals); food chains; and ice break-up. (JN)

  3. 40 CFR 81.113 - Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Savannah (Georgia)-Beaufort (South... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.113 Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region. The Savannah (Georgia)-Beaufort (South...

  4. 40 CFR 81.113 - Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Savannah (Georgia)-Beaufort (South... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.113 Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region. The Savannah (Georgia)-Beaufort (South...

  5. 40 CFR 81.113 - Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Savannah (Georgia)-Beaufort (South... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.113 Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region. The Savannah (Georgia)-Beaufort (South...

  6. 40 CFR 81.113 - Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Savannah (Georgia)-Beaufort (South... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.113 Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region. The Savannah (Georgia)-Beaufort (South...

  7. 40 CFR 81.113 - Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Savannah (Georgia)-Beaufort (South... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.113 Savannah (Georgia)-Beaufort (South Carolina) Interstate Air Quality Control Region. The Savannah (Georgia)-Beaufort (South...

  8. Crustal-scale geological and thermal models of the Beaufort-Mackenzie Basin, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Kröger, Karsten; Lewerenz, Björn

    2010-05-01

    of Tertiary deltaic sequences, AAPG Bulletin, 92(2): 225-247. Kroeger, K.F., di Primio, R. and Horsfield, B., (2009). Hydrocarbon flow modeling in complex structures (Mackenzie Basin, Canada), AAPG Bulletin, 93(9): 1-25. O'Leary, D.M., Ellis, R.M., Stephenson, R.A., Lane, L.S. and Zelt, C.A., 1995. Crustal structure of the northern Yukon and Mackenzie Delta, northwestern Canada, Journal of Geophysical Research 100(B7): 9905-9920. Stephenson, R.A., Coflin, K.C., Lane, L.S. and Dietrich, J.R., 1994. Crustal structure and tectonics of the southeastern Beaufort Sea continental margin, Tectonics, 13(2): 389-400.

  9. Seasonal variation of the Beaufort shelfbreak jet and its relationship to Arctic cetacean occurrence

    NASA Astrophysics Data System (ADS)

    Lin, Peigen; Pickart, Robert S.; Stafford, Kathleen M.; Moore, G. W. K.; Torres, Daniel J.; Bahr, Frank; Hu, Jianyu

    2016-12-01

    Using mooring time series from September 2008 to August 2012, together with ancillary atmospheric and satellite data sets, we quantify the seasonal variations of the shelfbreak jet in the Alaskan Beaufort Sea and explore connections to the occurrences of bowhead and beluga whales. Wind patterns during the 4 year study period are different from the long-term climatological conditions that the springtime peak in easterly winds shifted from May to June and the autumn peak was limited to October instead of extending farther into the fall. These changes were primarily due to the behavior of the two regional atmospheric centers of action, the Aleutian Low and Beaufort High. The volume transport of the shelfbreak jet, which peaks in the summer, was decomposed into a background (weak wind) component and a wind-driven component. The wind-driven component is correlated to the Pt. Barrow, AK alongcoast wind speed record although a more accurate prediction is obtained when considering the ice thickness at the mooring site. An upwelling index reveals that wind-driven upwelling is enhanced in June and October when storms are stronger and longer-lasting. The seasonal variation of Arctic cetacean occurrence is dominated by the eastward migration in spring, dictated by pack-ice patterns, and westward migration in fall, coincident with the autumn peak in shelfbreak upwelling intensity.

  10. Environmental Measurements in the Beaufort Sea, Spring 1990

    DTIC Science & Technology

    1990-12-01

    is limited. The data were collected to document the meteorological and oceanographic conditions that existed during camp activities , and to furnish...insight into the underwater sound-speed structure and ambient noise during camp activities , and to furnish insight into the underwater sound-speed

  11. Late Tectonic history of Beaufort Sea - North Pacific area

    SciTech Connect

    McWhae, J.R.H.

    1985-02-01

    The Kaltag fault (and its northern associated splay, the Rapid fault array) is the sheared suture between the Eurasian-Alaskan plate and the North American plate in the area between the Mackenzie Delta and the Alaskan Border. This condition has been maintained throughout considerable additional phases of faulting and folding from mid-Cretaceous to the present. Previously, the Alaskan plate had been the northwestern nose of the North America plate. The interplate suture was deflected to the north as the Canadian Shield was approached. The Kaltag fault continued northeastward 2000 km seaward of the Sverdrup rim, northwest of the Canadian Arctic Island, and north of Greenland. The driving force was directed from the southwest by the Eurasian plate after its collision in Early Cretaceous (Hauterivian) with the North American plate and the docking of north-moving exotic terranes from the Pacific. During the early Tertiary, perhaps in concert with the accretion of the Okhotsk block to the Asian plate north of Japan, the northern Pacific subduction zone jumped southward to the Aleutian Arc where it has persisted until today. A distance of 800 km separates the stable shelf of the Canadian craton, at the Alberta Foothills thrust belt, from the subduction zone off Vancouver Island. The foreland thrust belt and the accretion of exotic terranes in Mesozoic and Tertiary times extended the continental crust of the North American plate westward to the present active transform margin with the Pacific plate along the Queen Charlotte fault zone.

  12. Beaufort Sea Methane Hydrate Exploration: Energy and Climate Change

    DTIC Science & Technology

    2011-05-27

    Branch Marine Geosciences Division i REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 3. DATES COVERED (From - To) Standard Form 298 (Rev. 8...NUMBER 5f. WORK UNIT NUMBER 2. REPORT TYPE1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 6. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NUMBER 7...11 Table of Tables Table 1: Core location, date and water column depth. …………………………………….. 5 Table 2: Estimates of the

  13. Coastal Oceanography in the Beaufort Sea, Summer 1985.

    DTIC Science & Technology

    1987-07-01

    shortage of time. Because of deteriorating weather conditions (40-knot winds , snow, and rain), depar- ture of the scientific party from the ship was...ice is evident, which helps to open up large areas west of Pt. Barrow and west of the Mackenzie River. The winds reported by the ship (Section III...presence of river water. This warm water would be expected to cause deterioration in the ice. At times, easterly winds move the ice eastward from Banks

  14. 1981 Beaufort Sea Current Records: A Data Report. Volume I.

    DTIC Science & Technology

    1982-06-01

    20154 13. 31. 23 34. -1.73 04/09/91 21:09 35. 35. 45 50. -1.7304/09/81 21124 57. 39. 55 70. -1.73 04/09/81 21:39 69. 37. 61 79. -1.7304/09/81 2154 91...1.55 04/14/81 20:39 -34. -4. 262 35. -1.55 04/14/81 20154 -27. -11. 248 29. -1.55 04/14/81 21:09 -30. -12. 247 32. -1.55 04/14/91 21:24 -34. -13...81 20:09 -85. 17. 281 87. -1.70 04/19/81 20:24 -88. 25. 296 92. -1.7004/19/81 ൜,39 -97. 16. 279 98. -1.70 04/19/81 20154 -95. 17. 290 97. -1.7004/19

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

    NASA Astrophysics Data System (ADS)

    Engels, Jennifer L.

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

  16. The Beaufort Gyre intensification and stabilization: A model-observation synthesis

    NASA Astrophysics Data System (ADS)

    Zhang, Jinlun; Steele, Michael; Runciman, Kay; Dewey, Sarah; Morison, James; Lee, Craig; Rainville, Luc; Cole, Sylvia; Krishfield, Richard; Timmermans, Mary-Louise; Toole, John

    2016-11-01

    A model-observation synthesis is conducted to investigate changes in the upper ocean circulation and stratification in the Canada Basin [CB] of the Arctic Ocean. Results show that the Beaufort Gyre [BG] has been generally intensifying during 1992-2015 in conjunction with changes in sea ice and the upper ocean including increasing sea surface height [SSH], sea ice and ocean speed, Ekman transport convergence and downwelling, and freshwater content, decreasing ice thickness and upper ocean salinity, shoaling summer halocline and mixed layer, and deepening winter halocline and mixed layer. Increasing Ekman transport convergence draws more water from surrounding areas into the CB, thus lowering SSH in those areas and raising SSH in the CB. The rate of change in the CB began to decrease in 2008 and the BG circulation appears to be stabilizing, if not relaxing slightly. This is reflected in the general plateauing of SSH, the intensity of the sea ice and ocean circulation, and various measures of the CB thermohaline stratification. The BG intensification and subsequent stabilization appear to have been strongly controlled by atmospheric changes in the CB characterized by generally increasing anticyclonic wind circulation and sea level pressure (SLP) before 2008 and falling wind strength and SLP to below-average levels in some years after 2008. Changes in SLP are highly correlated with changes in ocean surface stress curl and downwelling. Since 2008, the magnitude of the stress curl and downwelling in much of the CB has declined, contributing to BG stabilization. The general leveling-off of sea ice thickness also contributes to the stabilization by limiting melt water input to the CB that increases freshwater content. Temperatures in the Near Surface Temperature Maximum layer trended upward slightly over 1992-2015, which is closely correlated with decreasing sea ice thickness. Upper ocean heat content increased over the study period mainly due to strong temperature

  17. Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation.

    PubMed

    Hauser, Donna D W; Laidre, Kristin L; Stafford, Kathleen M; Stern, Harry L; Suydam, Robert S; Richard, Pierre R

    2016-12-21

    Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr(-1) ) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how

  18. New sedimentological evidence supporting a catastrophic meltwater discharge event along the Beaufort margin, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Klotsko, S.; Driscoll, N. W.; Keigwin, L. D.; Mendenhall, B.

    2015-12-01

    In 2013, a cruise on the USCGC Healy mapped the Beaufort margin from Barrow, AK into the Amundsen Gulf using a towed CHIRP subbottom profiler and a hull-mounted Knudsen CHIRP subbottom profiler to study the deglaciation of the margin. Sediment cores were also acquired. New grain size analyses for three sediment cores will be presented. These records help constrain the flooding events captured in the existing grain size data from JPC 15, just east of the Mackenzie trough. This core shows evidence of multiple ice rafted debris events that were likely sourced from the retreat of the Amundsen ice stream. These layers have peaks in grain size around ~20 microns compared to the ~5 micron average for the rest of the core. The grain size peaks correlate to the high amplitude reflectors observed in the seismic CHIRP data. Similar reflectors are observed in the seismic data from two of the new core locations, one in the Mackenzie trough and one east of the trough. The seismic data from these stations also record a thick sediment package that is ~7 meters thick at its depocenter. This layer is interpreted to record a massive meltwater discharge event that entered the Arctic via the Mackenzie River. Oxygen isotope data from JPC 15 support an event at this location based on the covarying benthic and planktonic records. In our conceptual model, the pulses of freshwater from the Amundsen Gulf likely freshened the margin sufficiently that the major discharge event was then able to push the system over the edge. This catastrophic glacial lake draining out the Mackenzie River into the Beaufort Sea and export out of the Arctic into the North Atlantic caused diminished meridional overturning circulation - slowing of the conveyor belt thermohaline circulation - which, in turn, potentially caused the Younger Dryas cold period.

  19. Behavior of bowhead whales of the Davis Strait and Bering/Beaufort stocks versus regional differences in human activities. Final report on Phase 2

    SciTech Connect

    Miller, G.W.; Davis, R.A.; Richardson, W.J.

    1991-07-01

    The objectives were to determine (1) whether there are differences in behavior between the Bering/Chukchi/Beaufort and the Davis Strait/Baffin Bay populations and (2), if so, whether the differences might be attributable to the long-term cumulative effects of exposure to the presumed greater amount of human activity in the former area. Phase 1 showed that there are some differences in behavior. The Phase 2 report documents the relative amounts of human activity in the two areas in 1974-86, and evaluates whether regional differences in whale behavior and in human activities may be related. Activities considered include bowhead hunting and other subsistence activities, commercial fishing and shipping, marine seismic exploration, offshore oil exploration, and low-level aircraft flights. Bering/Beaufort bowheads were subjected to at least 3-5 times as much human activity in 1974-86. Most differences in behavior between the two stocks were better explained by environmental or biological factors than by disturbance. However, for bowheads migrating in autumn, regional differences in behavior may be related to the whaling that occurs in the Beaufort Sea in autumn.

  20. Vertical Structure and Dynamics of the Beaufort Gyre Subsurface Layer from ADCP Obervations

    NASA Astrophysics Data System (ADS)

    Torres, D. J.; Krishfield, R. A.; Proshutinsky, A. Y.; Timmermans, M. L. E.

    2014-12-01

    As part of the Beaufort Gyre Observing System (BGOS), several Acoustic Doppler Current Profilers (ADCPs) have been maintained at moorings in different locations in the Canada Basin since 2005 to measure upper ocean velocities and sea ice motion. The ADCP data have been analyzed to better understand relationships among different components of forcing driving the sea ice and upper ocean layer including: winds, tides, and horizontal and vertical density gradients in the ocean. Specific attention is paid to data processing and analysis to separate inertial and tidal motions in these regions in the vicinity of the critical latitudes. In addition, we describe the dynamic characteristics of halocline eddies and estimate their kinetic energy and their role in the total energy balance in this region. Ice-Tethered Profiler (ITP) data are used in conjunction with the ADCP measurements to identify relationships between T-S and vertical velocity structures in the mixed layer and deeper. Seasonal and interannual variability in all parameters are also discussed and causes of observed changes are suggested.

  1. Sea ice as a tracer for circulation features associated with the Barrow area Bowhead whale feeding hotspot

    NASA Astrophysics Data System (ADS)

    Okkonen, S. R.; Ashjian, C. J.; Campbell, R. G.

    2010-12-01

    Satellite images of sea ice distribution are used to provide synoptic illustrations of generalized wind-current regimes that promote favorable feeding conditions for Bowhead whales on the western Beaufort shelf near Barrow, Alaska. Images of grease ice and broken ice show convergences zones along the southern flank of Barrow Canyon and parallel to the Beaufort coast when winds are weak. When winds from the east are moderate-to-strong, these convergence zones are absent from the shelf.

  2. Description of the Pungo River formation in Beaufort County

    USGS Publications Warehouse

    Kimrey, Joel O.

    1965-01-01

    This report describes the lithology and stratigraphy of the Pungo River Formation that underlies part of Beaufort County, North Carolina. The formation contains potentially economic beds of phosphatic sand. It is composed of interbedded phosphatic clays, diatomaceous clays, phosphatic limestones, silty claystones, coquinas, calcareous clays, and phosphatic sands. The P2 0-, content of the phosphatic sands ranges up to a known maximum of about 21 percent of the raw core sample. The above materials usually occur in definite zones, or horizons, in the formation that may be traced laterally across the county.

  3. Natural Gas Hydrates in the Offshore Beaufort-Mackenzie Basin-Study of a Feasible Energy Source II

    SciTech Connect

    Majorowicz, J. A. Hannigan, P. K.

    2000-09-15

    In the offshore part of Beaufort-Mackenzie Basin depth of methane hydrate stability reaches more than 1.5 km. However, there are areas in the western part of the basin where there are no conditions of methane hydrate stability. Construction of the first contour maps displaying thickness of hydrate stability zones as well as hydrate stability zone thicknesses below permafrost in the offshore area, shows that these zones can reach 1200 m and 900 m, respectively. Depth to the base of ice-bearing relict permafrost under the sea (depth of the -1{sup o}C isotherm-ice-bearing permafrost base) and regional variations of geothermal gradient are the main controlling factors. Hydrostatic pressures in the upper 1500 m are the rule. History of methane hydrate stability zone is related mainly to the history of permafrost and it reached maximum depth in early Holocene. More recently, the permafrost and hydrate zone is diminishing because of sea transgression. Reevaluation of the location of possible gas hydrate occurrences is done from the analysis of well logs and other indicators in conjunction with knowledge of the hydrate stability zone. In the offshore Beaufort-Mackenzie Basin, methane hydrate occurs in 21 wells. Nine of these locations coincides with underlying conventional hydrocarbon occurrences. Previous analyses place some of the hydrate occurrences at greater depths than proposed for the methane hydrate-stability zone described in this study. Interpretation of geological cross sections and maps of geological sequences reveals that hydrates are occurring in the Iperk-Kugmallit sequence. Hydrate-gas contact zones, however, are possible in numerous situations. As there are no significant geological seals in the deeper part of the offshore basin (all hydrates are within Iperk), it is suggested that overlying permafrost and hydrate stability zone acted as the only trap for upward migrating gas during the last tens of thousand of years (i.e., Sangamonian to Holocene)

  4. Wintertime variability of the Beaufort gyre in the Arctic Ocean derived from CryoSat-2/SIRAL observations

    NASA Astrophysics Data System (ADS)

    Mizobata, Kohei; Watanabe, Eiji; Kimura, Noriaki

    2016-03-01

    We processed the sea surface height measured by the SAR (Synthetic Aperture Radar)/Interferometric Radar Altimeter (SIRAL) on board CryoSat-2 (CS-2) and successfully estimated the monthly dynamic ocean topography (DOT) of the Arctic Ocean. The CS-2 monthly DOT showed the interannual and monthly variability of the Beaufort Gyre (BG) during winter between 2010/2011 and 2014/2015. The northward flow at the western edge of the BG was primarily estimated over the Chukchi Borderland (CBL). However, the BG extended across the CBL, and the northward flow was estimated over the Mendeleev Ridge in the winter of 2012/2013. Our analyses revealed a significantly variable BG in response to changes in the sea surface stress field. Our analysis indicated that (1) sea ice motion, driven by wind fields, acts as a driving force for the BG when sea ice motion was intensified during winter and (2) sea ice motion can also act as an inhibiting force for the BG when sea ice motion is weakened during winter. In addition, the relationship between the DOT, steric height, and ocean bottom pressure implied that the DOT during winter responded to varying wind stresses through baroclinic and barotropic adjustments. According to a tracer experiment, we inferred that in the winter of 2012/2013, the Pacific-origin water carried into the BG through the Barrow Canyon was transported to the northern shelf and shelf break of the Chukchi Sea rather than the CBL, which is where the Pacific-origin water had been transported in the other years of the observation period.

  5. The role of atmospheric synoptic conditions in the Beaufort and Chukchi seasonal ice zone

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Schweiger, A. J. B.

    2015-12-01

    How atmosphere and sea ice interact depends on the prevailing weather. Synoptic activities transport energy and moisture into the Arctic and modify the structure of the atmosphere, cloud conditions, and the surface energy budget over sea ice. The structure of the atmosphere, such as temperature inversions and specific humidity inversions are critical for the life cycle of Arctic clouds. Cloud radiative heating is an important component of the Arctic surface energy budget. The differences in the structure of the atmosphere, clouds, and the radiation balance at the surface under different synoptic conditions will determine which processes will govern the interaction between the atmosphere and clouds. In this study, dominant synoptic types over the Beaufort and Chukchi seasonal ice zone (BCSIZ) are identified using the ERA-Interim reanalysis data sets and a k-mean clustering synoptic classification algorithm. The synoptic classification algorithm categorizes individual weather events in the atmospheric reanalysis into four synoptic types with distinct signatures in baroclinicity and temperature advection. The typical structure of the atmosphere in ERA-Interim is determined for each synoptic type. In particular the structure of the summer atmosphere across the ice edge along 150°W and 140°W longitude will be the analyzed and evaluated with observations obtained from the Seasonal Ice Zone Reconnaissance Survey (SIZRS). Cloud conditions and cloud radiative forcings at the surface under different synoptic conditions are determined using satellite observations, from MODIS, CloudSat, and Calipso, and modeled clouds in reanalysis. The influence of synoptic conditions on the structure of atmosphere and cloud through heat and moisture transport is explored and the consequent effects on the surface energy budget in BCSIZ are assessed.

  6. Ecological characteristics of core-use areas used by Bering-Chukchi-Beaufort (BCB) bowhead whales, 2006-2012

    NASA Astrophysics Data System (ADS)

    Citta, John J.; Quakenbush, Lori T.; Okkonen, Stephen R.; Druckenmiller, Matthew L.; Maslowski, Wieslaw; Clement-Kinney, Jaclyn; George, John C.; Brower, Harry; Small, Robert J.; Ashjian, Carin J.; Harwood, Lois A.; Heide-Jørgensen, Mads Peter

    2015-08-01

    The Bering-Chukchi-Beaufort (BCB) population of bowhead whales (Balaena mysticetus) ranges across the seasonally ice-covered waters of the Bering, Chukchi, and Beaufort seas. We used locations from 54 bowhead whales, obtained by satellite telemetry between 2006 and 2012, to define areas of concentrated use, termed "core-use areas". We identified six primary core-use areas and describe the timing of use and physical characteristics (oceanography, sea ice, and winds) associated with these areas. In spring, most whales migrated from wintering grounds in the Bering Sea to the Cape Bathurst polynya, Canada (Area 1), and spent the most time in the vicinity of the halocline at depths <75 m, which are within the euphotic zone, where calanoid copepods ascend following winter diapause. Peak use of the polynya occurred between 7 May and 5 July; whales generally left in July, when copepods are expected to descend to deeper depths. Between 12 July and 25 September, most tagged whales were located in shallow shelf waters adjacent to the Tuktoyaktuk Peninsula, Canada (Area 2), where wind-driven upwelling promotes the concentration of calanoid copepods. Between 22 August and 2 November, whales also congregated near Point Barrow, Alaska (Area 3), where east winds promote upwelling that moves zooplankton onto the Beaufort shelf, and subsequent relaxation of these winds promoted zooplankton aggregations. Between 27 October and 8 January, whales congregated along the northern shore of Chukotka, Russia (Area 4), where zooplankton likely concentrated along a coastal front between the southeastward-flowing Siberian Coastal Current and northward-flowing Bering Sea waters. The two remaining core-use areas occurred in the Bering Sea: Anadyr Strait (Area 5), where peak use occurred between 29 November and 20 April, and the Gulf of Anadyr (Area 6), where peak use occurred between 4 December and 1 April; both areas exhibited highly fractured sea ice. Whales near the Gulf of Anadyr spent almost

  7. Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

    DTIC Science & Technology

    2012-09-30

    date Geophysical data type Source Time period acquired Buoy tracks IABP 12 hrly position data 1978-2012 Ice thickness SIZONet April campaigns 2009...addition to acquiring the data files, we have also been assembling related metadata. In the case of the IABP data, we have started creating a database

  8. Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

    DTIC Science & Technology

    2013-09-30

    2 Table 2: Datasets compiled to date Geophysical data type Source Time period acquired Buoy tracks IABP 12 hrly position data 1978-2012 Ice...concentratio NSIDC 1978-present In addition to acquiring the data files, we have also been assembling related metadata. In the case of the IABP data

  9. Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

    DTIC Science & Technology

    2013-09-30

    a drop or balloon sonde, which is low cost but cannot be guided, and a typical UAV, which provides guidance flexibility but uses costly avionics and...by incorporating the proposed IR sensors and ground­sky temperature difference algorithm into a tethered balloon borne payload (Figure 6).This...ceilometer was used to provide a cloud base reference measurement, as well as visual markings of altitudes where the balloon and its payload disappeared

  10. Mechanism of seasonal Arctic sea ice evolution and Arctic amplification

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Yul; Hamlington, Benjamin D.; Na, Hanna; Kim, Jinju

    2016-09-01

    Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents-Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.

  11. MITAS-2009 Expedition, U.S. Beaufort Shelf and Slope—Lithostratigraphy Data Report

    SciTech Connect

    Rose, K.; Johnson, J.E.; Phillips, S.C.; Smith, J.; Reed, A.; Disenhof, C.; Presley, J.

    2012-09-17

    The volume of methane released through the Arctic Ocean to the atmosphere and its potential role in the global climate cycle have increasingly become the focus of studies seeking to understand the source and origin of this methane. In 2009, an international, multi-disciplinary science party aboard the U.S. Coast Guard icebreaker Polar Sea successfully completed a trans-U.S. Beaufort Shelf expedition aimed at understanding the sources and volumes of methane across this region. Following more than a year of preliminary cruise planning and a thorough site evaluation, the Methane in the Arctic Shelf/Slope (MITAS) expedition departed from the waters off the coast of Barrow, Alaska in September 2009. The expedition was organized with an international shipboard science team consisting of 33 scientists with the breadth of expertise necessary to meet the expedition goals. NETL researchers led the expedition’s initial core processing and lithostratigraphic evaluations, which are the focus of this report. This data report is focused on the lithostratigraphic datasets from the recovered vibra cores and piston cores. Operational information about the piston and vibra cores such as date acquired, core name, total length, water depth, and geographic location is provided. Once recovered, gas samples were immediately collected from cores. In addition, each core was run through the Geotek multi-sensor core logger for magnetic susceptibility, P-wave velocity, resistivity, and gamma-density measurements (Rose et al., 2010). After the samples and measurements were completed, the cores were split into working and archive halves. Visual core descriptions of the archive half was completed for each core. Samples for shipboard smear slides, coarse fractions, and XRD analyses were collected, as well as corresponding samples for post-cruise grain size analysis from the working half of each core. Line scan images of the split core surfaces were collected post-expedition. The methods used to

  12. Tundra burning in 2007 - Did sea ice retreat matter?

    NASA Astrophysics Data System (ADS)

    Alexeev, Vladimir A.; Euskirchen, Eugénie S.; Cherry, Jessica E.; Busey, Robert C.

    2015-06-01

    The goal of this study was to assess the importance of the 2007 sea ice retreat for hydrologic conditions on the Alaskan North Slope, and how this may have influenced the outbreak of tundra fires in this region. This study concentrates on two years, 2007 and 1996, with different arctic sea ice conditions and tundra fire activity. The year of 2007 is characterized by a low summer sea ice extent (second lowest) and high tundra fire activity, while 1996 had high sea ice extent, and few tundra fires. Atmospheric lateral boundary forcing from the NCEP/NCAR Reanalysis drove the Weather Research and Forecast (WRF) model, along with varying sea ice surface forcing designed to delineate the role of sea ice. WRF runs successfully reproduced the differences between 1996 and 2007. Surprisingly, replacing sea ice conditions in 1996 run by those from 2007 and vice versa (2007 run with 1996 sea ice) did not change the overall picture. The atmospheric circulation in August of 1996 included a significant low-pressure system over the Beaufort and Chukchi Seas. However, in 2007, a high-pressure system dominated the circulation over the Beaufort Sea. It is argued that this difference in large-scale patterns, rather than retreat of sea ice, was responsible for anomalously dry and warm atmospheric conditions over the North Slope in summer and autumn 2007, suitable for high tundra fire activity. Circulation in 2012 is contrasted with that in 2007 to further stress its importance for local weather on the North Slope.

  13. 75 FR 81711 - Notice of Receipt of Petition for Decision That Nonconforming 1991 Rice Beaufort Double Trailers...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-28

    ... Nonconforming 1991 Rice Beaufort Double Trailers Are Eligible for Importation AGENCY: National Highway Traffic... Rice Beaufort Double trailers are eligible for importation. SUMMARY: This document announces receipt by the National Highway Traffic Safety Administration (NHTSA) of a petition for a decision that 1991...

  14. Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale

    NASA Astrophysics Data System (ADS)

    Meaden, G. Terence; Kochev, S.; Kolendowicz, L.; Kosa-Kiss, A.; Marcinoniene, Izolda; Sioutas, Michalis; Tooming, Heino; Tyrrell, John

    2007-02-01

    2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita's damage scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita's Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita's Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F'half = T / 2 = (B / 4) - 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F'double = T = (B / 2) - 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit scale has all the criteria needed for world-wide practical effectiveness.

  15. Polar bear aerial survey in the eastern Chukchi Sea: A pilot study

    USGS Publications Warehouse

    Evans, Thomas J.; Fischbach, Anthony S.; Schliebe, Scott; Manly, Bryan; Kalxdorff, Susanne; York, Geoff S.

    2003-01-01

    Alaska has two polar bear populations: the Southern Beaufort Sea population, shared with Canada, and the Chukchi/Bering Seas population, shared with Russia. Currently a reliable population estimate for the Chukchi/Bering Seas population does not exist. Land-based aerial and mark-recapture population surveys may not be possible in the Chukchi Sea because variable ice conditions, the limited range of helicopters, extremely large polar bear home ranges, and severe weather conditions may limit access to remote areas. Thus line-transect aerial surveys from icebreakers may be the best available tool to monitor this polar bear stock. In August 2000, a line-transect survey was conducted in the eastern Chukchi Sea and western Beaufort Sea from helicopters based on a U.S. Coast Guard icebreaker under the "Ship of Opportunity" program. The objectives of this pilot study were to estimate polar bear density in the eastern Chukchi and western Beaufort Seas and to assess the logistical feasibility of using ship-based aerial surveys to develop polar bear population estimates. Twenty-nine polar bears in 25 groups were sighted on 94 transects (8257 km). The density of bears was estimated as 1 bear per 147 km² (CV = 38%). Additional aerial surveys in late fall, using dedicated icebreakers, would be required to achieve the number of sightings, survey effort, coverage, and precision needed for more effective monitoring of population trends in the Chukchi Sea.

  16. The influence of the Mackenzie River plume on distribution and diversity of marine larval fish assemblages on the Canadian Beaufort Shelf

    NASA Astrophysics Data System (ADS)

    Wong, Sally; Walkusz, Wojciech; Hanson, Mark; Papst, Michael H.

    2013-11-01

    In the Beaufort Sea, freshwater input from the Mackenzie River creates a relatively warm and turbid plume across the coastal shelf region. To determine the influence of this plume on marine larval fish abundance, distribution, and assemblages, we sampled larval fish during July and August of 2007 using 500 μm bongo nets on transects across the plume gradient at three sampling stations per transect, along with oceanographic measurements. Three larval fish assemblages were identified within three distinct oceanographic zones: intense plume, diffuse plume and oceanic. The intense plume assemblage was dominated by Saffron cod (Eleginus gracilis) and Pacific herring (Clupea pallasii); the diffuse plume assemblage was dominated by the Pricklebacks (sub-family Lumpeninae); and the oceanic assemblage was dominated by Arctic cod (Boreogadus saida). Even though there were differences in relative abundance of particular species among these areas, no significant differences in total abundances of larval fish were found.

  17. Variations of the abundance and nucleic acid content of heterotrophic bacteria in Beaufort Shelf waters during winter and spring

    NASA Astrophysics Data System (ADS)

    Belzile, Claude; Brugel, Sonia; Nozais, Christian; Gratton, Yves; Demers, Serge

    2008-12-01

    Depth profiles of heterotrophic bacteria abundance were measured weekly over a 6-month period from December to May in Franklin Bay, a 230 m-deep coastal Arctic Ocean site of the southeastern Beaufort Sea. Total bacteria, low nucleic acid (LNA) and high nucleic acid (HNA) bacteria abundances were measured using flow cytometry after SYBR Green I staining. The HNA bacteria abundance in surface waters started to increase 5-6 weeks after phytoplankton growth resumed in spring, increasing from 1 × 10 5 to 3 × 10 5 cells mL - 1 over an 8-week period, with a net growth rate of 0.018 d - 1 . LNA bacteria response was delayed by more than two months relative to the beginning of the phytoplankton biomass accumulation and had a lower net growth rate of 0.013 d - 1 . The marked increase in bacterial abundance occurred before any significant increase in organic matter input from river discharge (as indicated by the unchanged surface water salinity and DOC concentrations), and in the absence of water temperature increase. The abundance of bacteria below the halocline was relatively high until January (up to 5 × 10 5 cells mL - 1 ) but then decreased to values close to 2 × 10 5 cells mL - 1 . The three-fold bacterial abundance increase observed in surface waters in spring was mostly due to HNA bacteria, supporting the idea that these cells are the most active.

  18. Degrading permafrost and gas hydrate under the Beaufort Shelf and marine gas hydrate on the adjacent continental slope

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Hughes Clarke, J. E.; Blasco, S.; Melling, H.; Lundsten, E.; Vagle, S.; Collett, T. S.

    2011-12-01

    The sub-seafloor under the Arctic Shelf is arguably the part of the Earth that is undergoing the most dramatic warming. In the southern Beaufort Sea, the shelf area was terrestrially exposed during much of the Quaternary period when sea level was ~120m lower than present. As a consequence, many areas are underlain by >600m of ice-bonded permafrost that conditions the geothermal regime such that the base of the methane hydrate stability can be >1000m deep. Marine transgression has imposed a change in mean annual surface temperature from -15°C or lower during periods of terrestrial exposure, to mean annual sea bottom temperatures near 0°C. The thermal disturbance caused by transgression is still influencing the upper km of subsurface sediments. Decomposition of gas hydrate is inferred to be occurring at the base and the top of the gas hydrate stability zone. As gas hydrate and permafrost intervals degrade, a range of processes occur that are somewhat unique to this setting. Decomposition of gas hydrate at depth can cause sediment weakening, generate excess pore water pressure, and form free gas. Similarly, thawing permafrost can cause thaw consolidation, liberate trapped gas bubbles in ice bonded permafrost. Understanding the connection between deep subsurface processes generated by transgression, surficial sediment processes near the seafloor, and gas flux into the ocean and atmosphere is important to assessing geohazard and environmental conditions in this setting. In contrast, conditions for marine gas hydrate formation occur on the adjacent continental slope below ~270m water depths. In this paper, we present field observations of gas venting from three geologically distinct environments in the Canadian Beaufort Sea, two on the shelf and one on the slope. A complimentary paper by Dallimore et al reviews the geothermal changes conditioning this environment. Vigorous methane venting is occurring over Pingo-Like-Features (PLF) on the mid-shelf. Diffuse venting of

  19. Particulate matter in pack ice of the Beaufort Gyre

    USGS Publications Warehouse

    Reimnitz, E.; Barnes, P.W.; Weber, W.S.

    1993-01-01

    Fine sediment occurred in very small patches of turbid ice, as thin spotty surface layers, in mud pellets or in old snowdrifts. The latter were widespread south of 74??N, containing an estimated 22 tonnes of silt and clay km-2. Average particle concentration in sea ice (40 mg1-1) was much higher than in sea water (0.8 mg 1 -1) or in new snow. Assuming one-third of the load is released each year, the estimated deposition rate would equal the measured Holocene rate (~2cm 1000 year-1). Therefore, modern sea-ice rafting represents a substantial fraction of the total Arctic Ocean sediment budget. -from Authors

  20. Interaction of oil with arctic sea ice

    SciTech Connect

    Thomas, D.R.

    1983-02-01

    The purpose of the paper is to summarize relavant knowledge about the interactions between arctic sea ice and oil. The completion of further experimental oil spill studies, along with recent laboratory studies of the interaction of oil and sea ice and studies of environmental conditions, makes an updating of those works desirable. An attempt is made to identify the major factors in the interaction between oil and arctic sea ice and to present them in a way that defines the scope of the problem. Generally, the paper is restricted to factors that can be expected to play a major role in the sequence of events following a large under-ice blowout in the Beaufort Sea during winter.

  1. Supplementary Measurements in the Beaufort/Chukchi 2015 MIZ

    DTIC Science & Technology

    2015-09-30

    Emerging Dynamics Of The Marginal Ice Zone DRI allowed us to autonomously examine one year’s evolution of the lower atmosphere, sea ice and upper- ocean ...parameters in order to investigate whether waves travelling into the pack from the open ocean play a significant role in sea ice breakup and subsequent melt...scratch (3 x WBs, 3 x IMBs and 1 x AWS). Funding was approved in the latter half of May, and shipping from Europe to Alaska needed to be performed by mid

  2. Coupling a Thermodynamic Sea Ice Model with WRF

    NASA Astrophysics Data System (ADS)

    Krieger, J. R.; Zhang, J.

    2009-12-01

    Sea ice plays a significant role in shaping the atmospheric dynamics of the Arctic and surrounding regions through the modification of surface characteristics such as surface roughness, heat conductivity, and albedo. These in turn have both thermodynamic impacts on the surface heat budget and direct dynamic impacts on the low-level winds. In numerical atmospheric models, the accurate treatment of sea ice is therefore of critical importance in producing realistic simulations, not only on the global scale but at local and regional scales as well. However, sea ice is an often-neglected component of mesoscale meteorological models, many times being treated as just another land cover type without the sufficient complexity necessary to properly characterize its thermodynamic effects. To address this deficiency, we have recently coupled a thermodynamic sea ice model with the latest version of the Weather Research and Forecasting (WRF) model in order to improve the latter's simulation of sea ice surface temperatures, and by extension its simulation of Arctic conditions as a whole. A series of case studies was performed in which results from the coupled and unmodified versions of WRF were compared to determine the efficacy of this approach in improving weather simulations along the Beaufort and Chukchi Sea coasts in northern Alaska. In addition to surface station data, observations made as part of the SHEBA and SEDNA field campaigns and by two buoys recently deployed in the Beaufort Sea were used to verify the model output.

  3. Spatial Variability of Land-Sea Carbon Exchange at a Coastal Area in Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Ikawa, H.; Oechel, W.; Hastings, S.

    2007-12-01

    Relatively cold and low salinity sea water of the Arctic Ocean was considered to be a sink for atmospheric CO2 (Takahashi et al., 1997) because the solubility of CO2 in seawater increases as temperature decreases, and the arctic sea water transports CO2 to greater depths. However, carbon exchange in the Arctic sea is not well evaluated yet, because available data is very limited (Semiletov et al., 2007). Also, terrestrial inflows, such as thawing permafrost and coastal erosion, also affect oceanic air-sea CO2 exchange especially in the Arctic (ACIA., 2004) creating a variety of regional carbon cycles (Semiletov et al., 2007). Our aim is to quantify an air-sea CO2 exchange of a spatially wide coastal sea area, in Barrow, Alaska and to extrapolate the future carbon cycle in response to climate change. Boat cruises for pCO2 measurements operated from July 29 to August 5, 2007. The surveyed area was mainly divided into three parts: Chukchi Sea, Beaufort Sea, and Elson Lagoon. Conductivity of sea surface (CS) and sea surface temperature (SST) were also measured together with pCO2. The result showed distinct differences in pCO2 among three areas. Average delta pCO2 (dpCO2) (a difference between an atmospheric CO2 and pCO2), CS, and SST were -114.9 ppm, 47.0 mScm-1, and 8.0 C at Chukchi Sea, -53.1 ppm, 43.5 mScm-1, and 8.9 C at Beaufort Sea, and 43.7 ppm, 41.1 mScm-1, and 9.5 C at Elson Lagoon. Relatively high dpCO2 value in the Beaufort Sea implies a large terrestrial input from Elson Lagoon where dpCO2 value is positive. This is supported by lower CS in the Beaufort Sea and Elson Laggon than in the Chukchi Sea. Sea currents from Pacific Ocean, which continuously flow through the Chukchi Sea, are thought to carry warmer water. However, SST was lower in the Chukchi Sea than in the Beaufort Sea. This may be because a prevailing wind from north east creates Ekman transport causing an upwelling along the Chukchi Sea coast and this upwelling carries deep cold water to the

  4. Assimilating QuikSCAT SeaWinds With WRF Model for High Latitude Sea Breeze Simulation

    NASA Astrophysics Data System (ADS)

    Fan, X.; Zhang, J.; Krieger, J. R.; Morton, D. J.; Shulski, M. D.; Klene, A. E.; Zhang, X.

    2007-12-01

    Sea breezes along the Arctic coastal areas, especially in the Beaufort Sea coast, are associated with seasonal change of solar insolation, sea ice retreat, and complex terrain of the Brooks Range. Improvement of sea surface wind simulation with a high resolution mesoscale model is of particular interest in oil spill impact assessment and management, as well as in coastal erosion assessment. The objective of this study is to use the mesoscale weather research and forecast (WRF) model with satellite data assimilation to achieve a high quality simulation of Beaufort Sea regional weather patterns. The SeaWinds instrument onboard the polar-orbiting quick scatterometer (QuikSCAT) satellite is a specialized radar that measures ice-free ocean surface wind speed and direction. This data provides significant information over open water areas, where conventional observations are very sparse, for model validation and simulation improvement. The QuikSCAT SeaWinds level 2B data which have a horizontal resolution of 12.5 km are assimilated into the WRF model and its three-dimensional variational data assimilation system (WRF-Var) to study the impacts of QuikSCAT data on WRF simulations of surface wind fields and sea breezes. The modeling domain has been setup to cover the Beaufort Sea area with 235x136 grid points at 10 km resolution and is centered at (155W, 71.3N). In order to apply the WRF-Var system, a customized WRF model error statistics and length scales are created using a one-year simulation of WRF for this particular domain. Two 5-day periods, 10/01/2002-10/05/2000 and 9/20/2004-9/24/2004, are selected to conduct our case study. The years 2002 and 2004 had most open water area, i.e., the farthest ice retreat, during recent seven years; and thus, there are more QuikSCAT SeaWinds data available for our study. Preliminary results show that the WRF model is capable of simulating wind fields very well by verifying modeled winds with station observations. Further results on

  5. 75 FR 18404 - Safety Zone; FRONTIER DISCOVERER, Outer Continental Shelf Drillship, Chukchi and Beaufort Sea...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-12

    ... DRILLSHIP will significantly reduce the threat of allisions, oil spills, and releases of natural gas, and... would significantly reduce the threat of allisions, oil spills, and releases and increase the safety of... reduction of risk of allisions, oil spills, and releases of natural gas, and thereby protect the safety...

  6. 75 FR 803 - Safety Zone; FRONTIER DISCOVERER, Outer Continental Shelf Drillship, Chukchi and Beaufort Sea...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... around the DRILLSHIP will significantly reduce the threat of allisions, oil spills, and releases of... safety zone. The proposed regulation would reduce significantly the threat of allisions, oil spills,...

  7. 77 FR 10707 - Safety Zone; NOBLE DISCOVERER, Outer Continental Shelf Drillship, Chukchi and Beaufort Seas, Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ..., which could result in oil spills, and releases of natural gas, and thereby protect the safety of life... result in oil spills, and releases. Furthermore, the proposed regulation would increase the safety...

  8. Artic oil-spill response guide for the alaskan beaufort sea. Final report

    SciTech Connect

    Not Available

    1988-03-01

    Contents include--Federal Response Organization; Initial Response; Elements of Response; Detection and Surveillance, Oil-Spill Trajectory Models, Oil-Spill Containment, Oil-Spill Recovery, Transfer Equipment, Recovered Oil Storage Equipment, Oil-Spill Disposal, Personnel, Logistics, Well Control, Dispersants, Mechanics of Response, Oil Spill Response Scenarios; Appendices.

  9. EMBATTLED BIVALVES: BIOGEOGRAPHIC DISTRIBUTIONS AND ABUNDANCES FROM THE BEAUFORT SEA TO THE GULF OF CALIFORNIA

    EPA Science Inventory

    As part of an EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change, we have synthesized in a web-based tool, the Coastal Biogeographic Risk Analysis Tool (CBRAT), the biogeographic distributions and abundances of bivalves, found in dept...

  10. Toward a Predictive Model of Arctic Coastal Retreat in a Warming Climate, Beaufort Sea, Alaska

    DTIC Science & Technology

    2012-09-30

    quantify the environmental drivers of rapid coastal erosion in the Arctic, and to begin developing predictive models of future rates of coastal erosion ...wave) energy in driving coastal erosion in the Arctic. We are combining high-resolution observations of coastline retreat with meteorological and...content, ice-wedge polygon spacing, and the thermal properties of bluff materials; 2) time-lapse photography to observe coastal erosion processes in

  11. Coastal Environment, Bathymetry and Physical Oceanography along the Beaufort, Chukchi and Bering Seas.

    DTIC Science & Technology

    1980-01-01

    Porn --tlobl o- 1350 32ao, 33Geot"anAc 3 3 234 Enrll. o. Nort 1964 le trsrro n rktdo et S Mloot Aol lo ’,lole t,l O’elo P.wel ROW . 19 M~t’~ldte...rahkit and 7,Pder Porn p1 i ko A’ter perproslle Irneen el,. AmsA-- Vsbrecak jnea AV o Inc tlSIsl, Cenossla noilheltin Alakn Alaska. uS. Gedlogsal Ssrot...Snowsee. National Reaegrcb Council. 00. 76 712. Front Eftects Laboratory. Sono. Tedisewal Rapes 2. no Anrti G eesmee Proems. U S. Geological Stingy. Reid. B

  12. Aerial Surveys of Endangered Whales in the Beaufort, Chukchi & Northern Bering Seas.

    DTIC Science & Technology

    1982-03-01

    sighted north of Cape Prince of Wales . One hundred and sixty-seven beluga , including cow-calf pairs, and 15 aringed seals including cow-pup pairs were... Wales and Cape Sabine), 4 belugas at Pt. Lay, and 3 walrus. 168 165 162 159 156 153 150 71 71 70 - 70 69 69 68 68 67 67 67 ___ 1 .KEY FOR FLIGHT 89 66...sonobuoys, that beluga whales were present. Currently we assume that problems *of sightability are smoothed over time through repetitive sampling of an

  13. Aerial Surveys of Endangered Whales in the Beaufort, Eastern Chukchi, and Northern Bearing Seas, 1982.

    DTIC Science & Technology

    1983-06-01

    3000 ft). Th~ese images of the meter stick were measured and used in an attempt to calibrate the measurement of wales from photographs. 101 I I S1. Time...APRIL, MAY) survey Effort and Rationale I In the spring, flight effort was designed to find and follow bowhead wales migrating northward through the... beluga whale in Alaska. Alaska Department of Fish and Game. Federal Arctic Wildlife Restoration Project Report, Vol. 7. Krogman, BD, RM Sonntag, DJ Rugh, J

  14. Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-1

    NASA Technical Reports Server (NTRS)

    Reimnitz, E. (Principal Investigator); Barnes, P. W.

    1973-01-01

    The author has identified the following significant results. The particulate transport processes involved in the movement of surficial waters were examined using secchi disc readings, light attenuation coefficients, and particulate weights from filtration. Observations gathered during the summers of 1971 and 1972 indicate a remarkable difference in particulate matter and turbidity between the two years. ERTS-1 imagery during August 1972 showed turbid water along the northern Alaska coast. The uniformity of distribution of the turbid water and the fact that the river discharge is low at this period suggest that the turbidity is related to causes other than river effluent. Studies indicate that wave action is a more significant factor influencing particulate transport than believed heretofore. The boundary between the essentially immobile shorefast ice and the moving pack ice has been plotted from several ERTS-1 images and found to occur fairly consistently along the 20 meter contour. Considering the vast difference in the amount of ice movement shoreward and seaward of this boundary, ice-bottom action should also be different on either side of this boundary and for that matter at the shear zone that develops along the boundary.

  15. Contaminants in molting long-tailed ducks and nesting common eiders in the Beaufort Sea

    USGS Publications Warehouse

    Franson, J.C.; Hollmén, Tuula E.; Flint, P.L.; Grand, J.B.; Lanctot, Richard B.

    2004-01-01

    In 2000, we collected blood from long-tailed ducks (Clangula hyemalis) and blood and eggs from common eiders (Somateria mollissima) at near-shore islands in the vicinity of Prudhoe Bay, Alaska, and at a reference area east of Prudhoe Bay. Blood was analyzed for trace elements and egg contents were analyzed for trace elements, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Except for Se (mean=36.1 ??g/g dry weight (dw) in common eiders and 48.8 ??g/g dw in long-tailed ducks), concentrations of trace elements in blood were low and, although several trace elements differed between areas, they were not consistently higher at one location. In long-tailed ducks, Se in blood was positively correlated with activities of two serum enzymes, suggestive of an adverse effect of increasing Se levels on the liver. Although common eiders had high Se concentrations in their blood, Se residues in eggs were low (mean=2.28 ??g/g dw). Strontium and Ni were higher in eggs near Prudhoe Bay than at the reference area, but none of the other trace elements or organic contaminants in eggs differed between locations. Concentrations of Ca, Sr, Mg, and Ni differed among eggs having no visible development, early-stage embryos, or late-stage embryos. Residues of 4,4???-DDE, cis-nonachlor, dieldrin, hexachlorobenzene, oxychlordane, and trans-nonachlor were found in 100% of the common eider eggs, but at low concentrations (means of 2.35-7.45 ??g/kg wet weight (ww)). The mean total PCB concentration in eggs was 15.12 ??g/kg ww. Of PAHs tested for, residues of 1- and 2-methylnaphthalene and naphthalene were found in 100% of the eggs, at mean concentrations of 0.36-0.89 ??g/kg ww.

  16. Movement of Satellite-Tracked Buoys in the Beaufort Sea (1979-1981).

    DTIC Science & Technology

    1983-06-01

    34Of 4,mtMO- D.L. Murphy, I.M. Lissauer , and J.C. Myers CGR&DC 4/83 9. a’im 0 N w.. Wi..ss |. fie 14. (TRAM United States Coast Guard Research and...Eastern Mid-Latitude North Pacific. Journal of Geophysical Research, Vol. 86(C9): 8022-8030. Murphy, D.L., P.A. Tebeau, and I.M. Lissauer , 1981. Long

  17. BIVALVE BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND CLIMATE VULNERABILITY FROM THE BEAUFORT SEA TO THE GULF OF CALIFORNIA

    EPA Science Inventory

    As part of an U.S. EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change along the Pacific Coast, we have synthesized the biogeographic distributions and abundances of bivalves found in depths <200 m. We have included the twelve &ldqu...

  18. Toward a Predictive Model of Arctic Coastal Retreat in a Warming Climate, Beaufort Sea, Alaska

    DTIC Science & Technology

    2008-09-30

    meteorological and sedimentological data from the field, and submitted two abstracts for the AGU annual meeting in December. During this period, we also...describing the stratigraphy , ice content, and spatial variability of coastal bluffs materials; 2) to begin our long-term meteorological monitoring...environments. A. Coastal Stratigraphy – One of the advantages of arriving on the North Slope early in the summer was the ability to walk on

  19. "Heavy Sledding": Barriers to Community Participation in Beaufort Sea Hydrocarbon Developments.

    ERIC Educational Resources Information Center

    Durst, Douglas

    1994-01-01

    This description of the Canadian government's assessment of the social impact of hydrocarbon exploration in the Arctic demonstrates barriers to citizen involvement: ad hoc nature, travel and child care problems, and lack of enough volunteers. Recommendations for community participation in impact assessment are given. (SK)

  20. Contaminants in molting long-tailed ducks and nesting common eiders in the Beaufort Sea.

    PubMed

    Franson, J C; Hollmén, T E; Flint, P L; Grand, J B; Lanctot, R B

    2004-03-01

    In 2000, we collected blood from long-tailed ducks (Clangula hyemalis) and blood and eggs from common eiders (Somateria mollissima) at near-shore islands in the vicinity of Prudhoe Bay, Alaska, and at a reference area east of Prudhoe Bay. Blood was analyzed for trace elements and egg contents were analyzed for trace elements, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Except for Se (mean=36.1 microg/g dry weight (dw) in common eiders and 48.8 microg/g dw in long-tailed ducks), concentrations of trace elements in blood were low and, although several trace elements differed between areas, they were not consistently higher at one location. In long-tailed ducks, Se in blood was positively correlated with activities of two serum enzymes, suggestive of an adverse effect of increasing Se levels on the liver. Although common eiders had high Se concentrations in their blood, Se residues in eggs were low (mean=2.28 microg/g dw). Strontium and Ni were higher in eggs near Prudhoe Bay than at the reference area, but none of the other trace elements or organic contaminants in eggs differed between locations. Concentrations of Ca, Sr, Mg, and Ni differed among eggs having no visible development, early-stage embryos, or late-stage embryos. Residues of 4,4'-DDE, cis-nonachlor, dieldrin, hexachlorobenzene, oxychlordane, and trans-nonachlor were found in 100% of the common eider eggs, but at low concentrations (means of 2.35-7.45 microg/kg wet weight (ww)). The mean total PCB concentration in eggs was 15.12 microg/kg ww. Of PAHs tested for, residues of 1- and 2-methylnaphthalene and naphthalene were found in 100% of the eggs, at mean concentrations of 0.36-0.89 microg/kg ww.

  1. Outer continental shelf, Beaufort Sea, oil and gas lease sale 170 (proposed notice of sale)

    SciTech Connect

    1997-12-31

    The Minerals Management Service (MMS) is issuing this proposed Notice of Sale under the Outer Continental Shelf (OCS) Lands Act (43 U.S.C. 1331-1356, as amended) and the regulations issued thereunder (30 CFR Part 256). A `Sale Notice Package,` containing this Notice and several supporting and essential documents referenced in the Notice, is available from the MMS Alaska OCS Regional Office Public Information Unit.

  2. Rates of summertime biological productivity in the Beaufort Gyre: A comparison between the low and record-low ice conditions of August 2011 and 2012

    NASA Astrophysics Data System (ADS)

    Stanley, Rachel H. R.; Sandwith, Zoe O.; Williams, William J.

    2015-07-01

    The Arctic Ocean is changing rapidly as the global climate warms but it is not well known how these changes are affecting biological productivity and the carbon cycle. Here we study the Beaufort Gyre region of the Canada Basin in August and use the large reduction in summertime sea ice extent from 2011 to 2012 to investigate potential impacts of climate warming on biological productivity. We use the gas tracers O2/Ar and triple oxygen isotopes to quantify rates of net community production (NCP) and gross oxygen production (GOP) in the gyre. Comparison of the summer of 2011 with the summer of 2012, the latter of which had record low sea ice coverage, is relevant to how biological productivity might change in a seasonally ice-free Arctic Ocean. We find that, in the surface waters measured here, GOP in 2012 is significantly greater than in 2011, with the mean basin-wide 2012 GOP = 38 ± 3 mmol O2 m- 2 d- 1 whereas in 2011, mean basin GOP = 16 ± 5 mmol O2 m- 2 d- 1. We hypothesize that this is because the lack of sea ice and consequent increase in light penetration allows photosynthesis to increase in 2012. However, despite the increase in GOP, NCP is the same in the two years; mean NCP in 2012 is 3.0 ± 0.2 mmol O2 m- 2 y- 1 and in 2011 is 3.1 ± 0.2 mmol O2 m- 2 y- 1. This suggests that the heterotrophic community (zooplankton and/or bacteria) increased its activity as well and thus respired the additional carbon produced by the increased photosynthetic production. In both years, stations on the shelf had GOP 3 to 5 times and NCP 2 to 10 times larger than the basin stations. Additionally, we show that in 2011, the NCP/GOP ratio is smallest in regions with highest ice cover, suggesting that the microbial loop was more efficient at recycling carbon in regions where the ice was just starting to melt. These results highlight that although satellite chlorophyll records show, and many models predict, an increase in summertime primary production in the Arctic Basin as it

  3. Sea ice loss enhances wave action at the Arctic coast

    USGS Publications Warehouse

    Overeem, I.; Anderson, R. Scott; Wobus, C.W.; Clow, G.D.; Urban, F.E.; Matell, N.

    2011-01-01

    Erosion rates of permafrost coasts along the Beaufort Sea accelerated over the past 50 years synchronously with Arctic-wide declines in sea ice extent, suggesting a causal relationship between the two. A fetch-limited wave model driven by sea ice position and local wind data from northern Alaska indicates that the exposure of permafrost bluffs to seawater increased by a factor of 2.5 during 1979-2009. The duration of the open water season expanded from ???45 days to ???95 days. Open water expanded more rapidly toward the fall (???0.92 day yr-1), when sea surface temperatures are cooler, than into the mid-summer (???0.71 days yr-1).Time-lapse imagery demonstrates the relatively efficient erosive action of a single storm in August. Sea surface temperatures have already decreased significantly by fall, reducing the potential impact of thermal erosion due to fall season storm waves. Copyright 2011 by the American Geophysical Union.

  4. Regional variability in sea ice melt in a changing Arctic.

    PubMed

    Perovich, Donald K; Richter-Menge, Jacqueline A

    2015-07-13

    In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of 101 cm. The mean ice equivalent surface melt was 48 cm and the mean bottom melt was 53 cm. On average, surface melting decreases moving northward from the Beaufort Sea towards the North Pole; however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions, summer melting in the central Arctic is not large enough to completely remove the sea ice cover.

  5. Regional variability in sea ice melt in a changing Arctic

    PubMed Central

    Perovich, Donald K.; Richter-Menge, Jacqueline A.

    2015-01-01

    In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of 101 cm. The mean ice equivalent surface melt was 48 cm and the mean bottom melt was 53 cm. On average, surface melting decreases moving northward from the Beaufort Sea towards the North Pole; however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions, summer melting in the central Arctic is not large enough to completely remove the sea ice cover. PMID:26032323

  6. Decadal variability of Arctic sea ice in the Canada Basin

    NASA Astrophysics Data System (ADS)

    Connor, L. N.

    2015-12-01

    A series of spring Arctic flight campaigns surveying a region over the Canada Basin, from 2006 to 2015, has resulted in unique observations that reveal new details of sea ice leads and freeboard evolution, during a decade of significant interannual variability in the Arctic ice cover. The series began in 2006 with a joint NASA/NOAA airborne altimetry campaign over a 1300 km survey line northwest of the Canadian Archipelago extending into the northern Beaufort Sea. Operation IceBridge (OIB) took up this flight line again in 2009 and repeated it annually through 2012. Additional observations have been collected along a 1000+ km flight line, in the southern Canada Basin and eastern Beaufort Sea, between 2009 and 2015. Here we examine laser altimetry, snow radar data, and high-resolution visible imagery to better understand the frequency and distribution of leads and ice floes, the characteristics of first- and multi-year ice types in the survey region, and their impact on the derivation and accuracy of sea ice freeboard. We demonstrate a novel lead detection methodology that depends only upon laser altimeter measurements, and we quantify the impact of low lead frequencies on estimates of instantaneous sea surface height. The analysis reveals a variable springtime freeboard north of 78° N, significantly reduced after 2006, and a notable lead outbreak over the Canada Basin during 2010.

  7. Interannual Arctic sea ice variability and associated winter weather patterns: A regional perspective for 1979-2014

    NASA Astrophysics Data System (ADS)

    Chen, Hans W.; Alley, Richard B.; Zhang, Fuqing

    2016-12-01

    Using Arctic sea ice concentration derived from passive microwave satellite observations in autumn and early winter over the 1979-2014 period, the Arctic region was objectively classified into several smaller regions based on the interannual sea ice variability through self-organizing map analyses. The trend in regional sea ice extent (RSIE) in each region was removed using an adaptive, nonlinear, and nonstationary method called Ensemble Empirical Mode Decomposition, which captures well the accelerating decline of Arctic RSIEs in recent decades. Although the linear trend in RSIE is negative in all regions in both seasons, there are marked differences in RSIE trends and variability between regions, with the largest negative trends found during autumn in the Beaufort Sea, the Barents-Kara Seas, and the Laptev-East Siberian Seas. Winter weather patterns associated with the nonlinearly detrended RSIEs show distinct features for different regions and tend to be better correlated with the autumn than early winter RSIE anomalies. Sea ice losses in the Beaufort Sea and the Barents-Kara Seas are both associated with a cooling of Eurasia, but in the former case the circulation anomaly is reminiscent of a Rossby wave train, whereas in the latter case the pattern projects onto the negative phase of the Arctic Oscillation. These results highlight the nonuniform changes in Arctic sea ice and suggest that regional sea ice variations may play a crucial role for the winter weather patterns.

  8. Interdecadal changes in snow depth on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Webster, Melinda A.; Rigor, Ignatius G.; Nghiem, Son V.; Kurtz, Nathan T.; Farrell, Sinead L.; Perovich, Donald K.; Sturm, Matthew

    2014-08-01

    Snow plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and IceBridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.1 ± 9.4 to 22.2 ± 1.9 cm in the western Arctic, and from 32.8 ± 9.4 to 14.5 ± 1.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37 ± 29% in the western Arctic and 56 ± 33% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

  9. Sedimentological and Stratagraphic Evidence for a Catastrophic Flood Along the Beaufort Margin, Arctic Ocean

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    In 2013, a cruise on the USCGC Healy mapped the Beaufort margin from Barrow, AK into the Amundsen Gulf using a towed CHIRP subbottom profiler and a hull-mounted Knudsen CHIRP subbottom profiler. Sediment cores were also acquired. The seismic data image an extensive margin-wide drift deposit, which appears to have entered the Beaufort margin from the Mackenzie River. The deposit is thickest on the eastern side of the Mackenzie Delta, near stations 5 and 9. It thins west along the Beaufort margin nearing Barrow Canyon. The deposit also thins to the east, but does not extend as far in this direction. Sediment core Healy1302-JPC15, from station 5 on the Mackenzie slope, was analyzed for grain size using a Laser Diffraction Particle Size Analyzer. These data were compared to the magnetic susceptibility data from the core. Peaks in the susceptibility correlate with increases in grain size, as well as high amplitude reflectors within the drift deposit present in the seismic data. The drift deposit appears to have a diagnostic reflection pattern observed in the seismic data with the base being characterized by a high amplitude reflector that correlates with increased IRD. Above the basal reflectors, an acoustically transparent interval is observed with thicknesses on the order of 7 m near the depocenter; this interval has diminished IRD and radiocarbon dates yield accumulation rates as high as 8 m/ky. The dominant grain size for this interval is ~5 μm. Above the transparent interval is a series of high amplitude reflectors defining the top of the drift deposit. The dominant grain size for the basal and upper high amplitude reflectors reaches ~20 μm. We postulate that the drift deposit was sourced from glacial Lake Agassiz and flowed down the Mackenzie River, entering the Arctic Ocean. It was then entrained by the Beaufort Gyre, migrating clockwise along the margin. Oxygen isotope data reflects the light δO18 signature consistent with a large glacial meltwater input

  10. Diagnostic sea ice predictability in the pan-Arctic and U.S. Arctic regional seas

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Blanchard-Wrigglesworth, Edward; Bitz, Cecilia M.; Ladd, Carol; Stabeno, Phyllis J.

    2016-11-01

    This study assesses sea ice predictability in the pan-Arctic and U.S. Arctic regional (Bering, Chukchi, and Beaufort) seas with a purpose of understanding regional differences from the pan-Arctic perspective and how predictability might change under changing climate. Lagged correlation is derived using existing output from the Community Earth System Model Large Ensemble (CESM-LE), Pan-Arctic Ice-Ocean Modeling and Assimilation System, and NOAA Coupled Forecast System Reanalysis models. While qualitatively similar, quantitative differences exist in Arctic ice area lagged correlation in models with or without data assimilation. On regional scales, modeled ice area lagged correlations are strongly location and season dependent. A robust feature in the CESM-LE is that the pan-Arctic melt-to-freeze season ice area memory intensifies, whereas the freeze-to-melt season memory weakens as climate warms, but there are across-region variations in the sea ice predictability changes with changing climate.

  11. An epidemiological investigation of an outbreak of leptospirosis associated with swimming, Beaufort, Sabah.

    PubMed

    Koay, T K; Nirmal, S; Noitie, L; Tan, E

    2004-10-01

    From October 13 to October 21, 1999, a total of 46 males, aged 8 to 19 years, were admitted to Beaufort Hospital after swimming in the creek near an oil palm plantation in Kampung (Kg) Kebatu, Beaufort. Thirty (30) presented with symptoms including fever, vomiting, bodyache, giddiness, headache, chest pain and cough, while 16 others, were asymptomatic. One, a 15 year old boy, died from haemorrhagic shock secondary to pulmonary haemorrhage. The onset of the illness was from 11 October to 19 October 1999. A case-control study found that the outbreak was associated with swimming in the creek (p<0.0001). A total of 44 paired sera samples were sent for microscopic agglutination test (MAT), 5 pairs showed sero-conversion, 3 pairs had 4 fold rise in titre and 18 pairs were positive at >320. The findings indicated that Leptospirosis was the cause of the outbreak of this illness and the contaminated creek water was the source of the infection. The occurrence of flooding and stagnation in the creek following the heavy rainfall during the first week of October 1999 could have contributed to the timing of the outbreak.

  12. EOS Aqua AMSR-E Arctic Sea Ice Validation Program

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus, T.; Gasiewski, A.; Klein, M.; Maslanik, J.; Sturm, M.; Stroeve, J.; Heinrichs, J.

    2004-01-01

    A coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed in March 2003. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4,2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products include sea ice concentration, sea ice temperature, and snow depth on sea ice. The primary instrument on the P-3B aircraft was the NOAA ETL Polarimetric Scanning Radiometer (PSR) covering the same frequencies and polarizations as the AMSR-E. This paper describes the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound. Comparisons among the satellite and aircraft PSR data sets are presented.

  13. Fine-resolution simulation of surface current and sea ice in the Arctic Mediterranean Seas

    NASA Astrophysics Data System (ADS)

    Liu, Xiying; Zhang, Xuehong; Yu, Rucong; Liu, Hailong; Li, Wei

    2007-04-01

    A fine-resolution model is developed for ocean circulation simulation in the National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Chinese Academy of Sciences, and is applied to simulate surface current and sea ice variations in the Arctic Mediterranean Seas. A dynamic sea ice model in elastic-viscous-plastic rheology and a thermodynamic sea ice model are employed. A 200-year simulation is performed and a dimatological average of a 10-year period (141st 150th) is presented with focus on sea ice concentration and surface current variations in the Arctic Mediterranean Seas. The model is able to simulate well the East Greenland Current, Beaufort Gyre and the Transpolar Drift, but the simulated West Spitsbergen Current is small and weak. In the March climatology, the sea ice coverage can be simulated well except for a bit more ice in east of Spitsbergen Island. The result is also good for the September scenario except for less ice concentration east of Greenland and greater ice concentration near the ice margin. The extra ice east of Spitsbergen Island is caused by sea ice current convergence forced by atmospheric wind stress.

  14. Microwave Signatures of Snow on Sea Ice: Modeling

    NASA Technical Reports Server (NTRS)

    Powell, D. C.; Markus, T.; Cavalieri, D. J.; Gasiewski, A. J.; Klein, M.; Maslanik, J. A.; Stroeve, J. C.; Sturm, M.

    2006-01-01

    Accurate knowledge of snow-depth distribution over sea ice is critical for polar climate studies. Current snow-depth-over-sea-ice retrieval algorithms do not sufficiently account for variations in snow and ice physical properties that can affect the accuracy of retrievals. For this reason, airborne microwave observations were coordinated with ground-based measurements of snow depth and snow properties in the vicinity of Barrow, AK, in March 2003. In this paper, the effects of snowpack properties and ice conditions on microwave signatures are examined using detailed surface-based measurements and airborne observations in conjunction with a thermal microwave-emission model. A comparison of the Microwave Emission Model of Layered Snowpacks (MEMLS) simulations with detailed snowpack and ice data from stakes along the Elson Lagoon and the Beaufort Sea and ra- 'diometer data taken from low-level flights using a Polarimetric Scanning Radiometer (PSR-A) shows that MEMLS can be used to simulate snow on sea ice and is a useful tool for understanding the limitations of the snow-depth algorithm. Analysis of radiance data taken over the Elson Lagoon and the Beaufort Sea using MEMLS suggests that the radiometric differences between the two locations are due to the differences in sea-ice emissivity. Furthermore, measured brightness temperatures suggest that the current snow-depth retrieval algorithm is sufficient for areas of smooth first-year sea ice, whereas new algorithm coefficients are needed for rough first-year sea ice. Snowpack grain size and density remain an unresolved issue for snow-depth retrievals using passive-microwave radiances.

  15. A crust-scale 3D structural model of the Beaufort-Mackenzie Basin (Arctic Canada)

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Lewerenz, Björn; Kroeger, Karsten Friedrich

    2013-04-01

    The Beaufort-Mackenzie Basin was initiated in the Early Jurassic as part of an Arctic rifted passive continental margin which soon after became overprinted by Cordilleran foreland tectonics. Decades of industrial exploration and scientific research in this petroliferous region have produced a wide spectrum of geological and geophysical data as well as geoscientific knowledge. We have integrated available grids of sedimentary horizons, well data, seismic reflection and refraction data, and the observed regional gravity field into the first crust-scale 3D structural model of the Beaufort-Mackenzie Basin. Many characteristics of this model reflect the complex geodynamic and tectonostratigraphic history of the basin. The Mesozoic-Cenozoic sedimentary part of the model comprises seven clastic units (predominantly sandy shales) of which the modelled thickness distributions allow to retrace the well-established history of the basin comprising a gradual north(east)ward shift of the main depocentres as well as diverse phases of localised erosion. As a result of this development, the present-day configuration of the basin reveals that the sedimentary units tend to be younger, more porous, and thus less dense towards the north at a constant depth level. By integrating three refraction seismic profiles and performing combined isostatic and 3D gravity modelling, we have modelled the sub-sedimentary basement of the Beaufort-Mackenzie Basin. The continental basement spans from unstretched domains (as thick as about 42 km) in the south to extremely thinned domains (of less than 5 km thickness) in the north where it probably represents transitional crust attached to the oceanic crust of the Canada Basin. The uppermost parts of the continental crust are less dense (ρ = 2710 kg/m3) and most probably made up by pre-Mesozoic meta-sediments overlying a heavier igneous and metamorphic crust (ρ = 2850 kg/m3). The presented crust-scale 3D structural model shows that the greatest

  16. Geometrical constraints on the evolution of ridged sea ice

    NASA Astrophysics Data System (ADS)

    Amundrud, Trisha L.; Melling, Humfrey; Ingram, R. Grant

    2004-06-01

    A numerical model of the evolving draft distribution of seasonal pack ice is driven by freezing and ice field compression in one dimension. Spatial transects of sea ice draft acquired during winter in the Beaufort Sea are used to evaluate the model. Histograms obtained by ice-profiling sonar on subsea moorings reveal changes in the draft distribution, while observations of ice velocity by Doppler sonar allow calculation of the strain to which the draft distribution is responding. Numerical diffusion in thermal ice growth is controlled using a remapping algorithm. Mechanical redistribution algorithms in common use generate much more deep ridged ice than is observed. Geometric constraints on ridge-keel development that reflect the finite extent of level floes available for ridge building and the true average shape of keels produce more realistic results. In the seasonal pack ice of the Beaufort Sea, 75% of all floes are too small to provide a volume of ice sufficient to construct a keel of draft equal to that commonly assumed in ice dynamics modeling. On average, the distribution of draft within keels has a negative exponential form, implying a cusped keel shape with more area on the thinner flanks than at the crest; models commonly assume a uniform redistribution of ice into a keel of triangular shape. Clearly, the spatial organization of ice within seasonal pack or, equivalently, the existence of ridges and floes should be an acknowledged factor in redistribution theory for pack ice thickness.

  17. The influence of declining sea ice on shipping activity in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Pizzolato, Larissa; Howell, Stephen E. L.; Dawson, Jackie; Laliberté, Frédéric; Copland, Luke

    2016-12-01

    Significant attention has focused on the potential for increased shipping activity driven by recently observed declines in Arctic sea ice cover. In this study, we describe the first coupled spatial analysis between shipping activity and sea ice using observations in the Canadian Arctic over the 1990-2015 period. Shipping activity is measured by using known ship locations enhanced with a least cost path algorithm to generate ship tracks and quantified by computing total distance traveled in kilometers. Statistically significant increases in shipping activity are observed in the Hudson Strait (150-500 km traveled yr-1), the Beaufort Sea (40-450 km traveled yr-1), Baffin Bay (50-350 km traveled yr-1), and regions in the southern route of the Northwest Passage (50-250 km traveled yr-1). Increases in shipping activity are significantly correlated with reductions in sea ice concentration (Kendall's tau up to -0.6) in regions of the Beaufort Sea, Western Parry Channel, Western Baffin Bay, and Foxe Basin. Changes in multiyear ice-dominant regions in the Canadian Arctic were found to be more influential on changes to shipping activity compared to seasonal sea ice regions.

  18. Arctic and Antarctic sea ice and climate

    NASA Astrophysics Data System (ADS)

    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

  19. Anchor ice, seabed freezing, and sediment dynamics in shallow arctic seas

    USGS Publications Warehouse

    Reimnitz, E.; Kempema, E.W.; Barnes, P.W.

    1987-01-01

    Diving investigations confirm previous circumstantial evidence of seafloor freezing and anchor ice accretion during freeze-up storms in the Alaskan Beaufort Sea. These related bottom types were found to be continuous from shore to 2 m depth and spotty to 4.5 m depth. The concretelike nature of frozen bottom, where present, should prohibit sediment transport by any conceivable wave or current regime during the freezing storm. But elsewhere, anchor ice lifts coarse material off the bottom and incorporates it into the ice canopy, thereby leading to significant ice rafting of shallow shelf sediment and likely sediment loss to the deep sea. -from Authors

  20. Upper Permian magnetic stratigraphy of the lower Beaufort Group, Karoo Basin

    NASA Astrophysics Data System (ADS)

    Lanci, L.; Tohver, E.; Wilson, A.; Flint, S.

    2013-08-01

    We carried out a magnetostratigraphic and geochronological study of late Permian sediments in the Karoo Basin of the Western Cape Province, South Africa. A continuous, ~700 m thick section of deltaic sediments of the upper Waterford Formation (uppermost Ecca Group) and the fluvial sediments of the Abrahamskraal Formation (lowermost Beaufort Group) were sampled at the meter scale. U-Pb dating of zircons from interbedded volcanic ash beds by ion microprobe (SHRIMP) provided absolute age constraints on the age of the sedimentary rocks. Paleomagnetic analysis reveals a partial overprint of the Natural Remanent Magnetization (NRM) that is tentatively ascribed to the emplacement of the Karoo Large Igneous Province in the Western Cape region during the middle Jurassic. A stable component of the NRM was found at temperatures higher than 450 °C and was interpreted as a Characteristic Remanent Magnetization (ChRM) acquired during deposition, supported by a positive reversals test for this dual polarity ChRM. The virtual geomagnetic pole position for the Waterford and Abrahamskraal Formations computed from the average ChRM direction is in general agreement with the late Permian directions for stable Gondwana. A significantly different average inclination, and thus paleomagnetic pole position, is obtained by correcting the inclination shallowing error by the Elongation-Inclination method (Tauxe and Kent, 2004). The presence of both normal and reversed polarity zones indicate deposition after the end of the Kiaman Superchron, moreover the polarity sequence is in good agreement with the Illawarra sequence of Steiner (2006). Our results indicate a Capitanian (late Guadalupian) age for the Abrahamskraal Fm., in agreement with the Late Permian age, based on presence of Glossopteris flora and Dicynodont fauna, traditionally assigned to the fluvial-lacustrine sediments of the Beaufort Group. However, the U-Pb zircon ages of ca. 264-268 Ma suggest an age of 269 Ma for the top of the

  1. Diminishing sea ice in the western Arctic Ocean

    USGS Publications Warehouse

    Stone, R.S.; Belchansky, G.I.; Drobot, Sheldon; Douglas, D.C.; Levinson, D.H.; Waple, A.M.

    2004-01-01

    Since the advent of satellite passive microwave radiometry (1978), variations in sea ice extent and concentration have been carefully monitored from space. An estimated 7.4% decrease in sea ice extent has occurred in the last 25 yr (Johannessen et al. 2004), with recent record minima (e.g., Maslanik et al. 1999; Serreze et al. 2003) accounting for much of the decline. Comparisons between the time series of Arctic sea ice melt dynamics and snowmelt dates at the NOAA–CMDL Barrow Observatory (BRW) reveal intriguing correlations.Melt-onset dates over sea ice (Drobot and Anderson 2001) were cross correlated with the melt-date time series from BRW, and a prominent region of high correlation between snowmelt onset over sea ice and the BRW record of melt dates was approximately aligned with the climatological center of the Beaufort Sea Anticyclone (BSA). The BSA induces anticyclonic ice motion in the region, effectively forcing the Beaufort gyre. A weak gyre caused by a breakdown of the BSA diminishes transport of multiyear ice into this region (Drobot and Maslanik 2003). Similarly, the annual snow cycle at BRW varies with the position and intensity of the BSA (Stone et al. 2002, their Fig. 6). Thus, variations in the BSA appear to have far-reaching effects on the annual accumulation and subsequent melt of snow over a large region of the western Arctic.A dramatic increase in melt season duration (Belchansky et al. 2004) was also observed within the same region of high correlation between onset of melt over the ice pack and snowmelt at BRW (Fig. 5.7). By inference, this suggests linkages between factors that modulate the annual cycle of snow on land and processes that influence melting of snow and ice in the western Arctic Ocean.

  2. Microwave Signatures of Snow on Sea Ice: Observations

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Cavalieri, Donald J.; Gasiewski, Albin J.; Klein, Marian; Maslanik, James A.; Powell, Dylan C.; Stankov, B. Boba; Stroeve, Julienne C.; Sturm, Matthew

    2006-01-01

    Part of the Earth Observing System Aqua Advanced Microwave Scanning Radiometer (AMSR-E) Arctic sea ice validation campaign in March 2003 was dedicated to the validation of snow depth on sea ice and ice temperature products. The difficulty with validating these two variables is that neither can currently be measured other than in situ. For this reason, two aircraft flights on March 13 and 19,2003, were dedicated to these products, and flight lines were coordinated with in situ measurements of snow and sea ice physical properties. One flight was in the vicinity of Barrow, AK, covering Elson Lagoon and the adjacent Chukchi and Beaufort Seas. The other flight was farther north in the Beaufort Sea (about 73 N, 147.5 W) and was coordinated with a Navy ice camp. The results confirm the AMSR-E snow depth algorithm and its coefficients for first-year ice when it is relatively smooth. For rough first-year ice and for multiyear ice, there is still a relationship between the spectral gradient ratio of 19 and 37 GHz, but a different set of algorithm coefficients is necessary. Comparisons using other AMSR-E channels did not provide a clear signature of sea ice characteristics and, hence, could not provide guidance for the choice of algorithm coefficients. The limited comparison of in situ snow-ice interface and surface temperatures with 6-GHz brightness temperatures, which are used for the retrieval of ice temperature, shows that the 6-GHz temperature is correlated with the snow-ice interface temperature to only a limited extent. For strong temperature gradients within the snow layer, it is clear that the 6-GHz temperature is a weighted average of the entire snow layer.

  3. Hydrologic and water-quality data in selected agricultural drainages in Beaufort and Hyde Counties, North Carolina, 1990-92

    USGS Publications Warehouse

    Treece, M.W.

    1993-01-01

    An investigation was begun in 1988 to: (1) quantify nutrient, sediment, and freshwater loadings in canals that collect drainage from cropland field ditches; (2) determine the effects of tide gates and flashboard risers on these loadings and on receiving water quality; and (3) characterize the effects of drainage on the salinity regime of a tidal creek. Data were collected in three canals in Hyde County, two canals in Beaufort County, and in Campbell Creek, which receives drainage directly from the Beaufort County canals. A tide gate was placed in one of the Hyde County canals near the beginning of the investigation. In August 1990 following more than 2 years of data collection, control structures were placed in the remaining two Hyde County canals. Flashboard risers were installed in the Beaufort County canals in April 1991. Hydrologic and water quality data are presented for each of the study sites for the period of October 1990 through May 1992. Following a description of the study sites and data collection methods, data are presented for the five drainage canals and Campbell Creek. The data collected included: (1) daily values of accumulated precipitation; (2) water level statistics; (3) daily mean values of discharge in the canals; (4) biweekly water quality measurements and sample analyses; (5) storm-event water quality measurements and sample analyses; (6) continuous records of specific conductance in the canals; (7) vertical profiles of salinity in Campbell Creek; and (8) daily mean values of salinity at five sites at Campbell Creek.

  4. Arctic Sea Level During the Satellite Altimetry Era

    NASA Astrophysics Data System (ADS)

    Carret, A.; Johannessen, J. A.; Andersen, O. B.; Ablain, M.; Prandi, P.; Blazquez, A.; Cazenave, A.

    2016-11-01

    Results of the sea-level budget in the high latitudes (up to 80°N) and the Arctic Ocean during the satellite altimetry era. We investigate the closure of the sea-level budget since 2002 using two altimetry sea-level datasets based on the Envisat waveform retracking: temperature and salinity data from the ORAP5 reanalysis, and Gravity Recovery And Climate Experiment (GRACE) space gravimetry data to estimate the steric and mass components. Regional sea-level trends seen in the altimetry map, in particular over the Beaufort Gyre and along the eastern coast of Greenland, are of halosteric origin. However, in terms of regional average over the region ranging from 66°N to 80°N, the steric component contributes little to the observed sea-level trend, suggesting a dominant mass contribution in the Arctic region. This is confirmed by GRACE-based ocean mass time series that agree well with the altimetry-based sea-level time series. Direct estimate of the mass component is not possible prior to GRACE. Thus, we estimated the mass contribution from the difference between the altimetry-based sea level and the steric component. We also investigate the coastal sea level with tide gauge records. Twenty coupled climate models from the CMIP5 project are also used. The models lead us to the same conclusions concerning the halosteric origin of the trend patterns.

  5. Arctic Sea Level During the Satellite Altimetry Era

    NASA Astrophysics Data System (ADS)

    Carret, A.; Johannessen, J. A.; Andersen, O. B.; Ablain, M.; Prandi, P.; Blazquez, A.; Cazenave, A.

    2017-01-01

    Results of the sea-level budget in the high latitudes (up to 80°N) and the Arctic Ocean during the satellite altimetry era. We investigate the closure of the sea-level budget since 2002 using two altimetry sea-level datasets based on the Envisat waveform retracking: temperature and salinity data from the ORAP5 reanalysis, and Gravity Recovery And Climate Experiment (GRACE) space gravimetry data to estimate the steric and mass components. Regional sea-level trends seen in the altimetry map, in particular over the Beaufort Gyre and along the eastern coast of Greenland, are of halosteric origin. However, in terms of regional average over the region ranging from 66°N to 80°N, the steric component contributes little to the observed sea-level trend, suggesting a dominant mass contribution in the Arctic region. This is confirmed by GRACE-based ocean mass time series that agree well with the altimetry-based sea-level time series. Direct estimate of the mass component is not possible prior to GRACE. Thus, we estimated the mass contribution from the difference between the altimetry-based sea level and the steric component. We also investigate the coastal sea level with tide gauge records. Twenty coupled climate models from the CMIP5 project are also used. The models lead us to the same conclusions concerning the halosteric origin of the trend patterns.

  6. Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2010-01-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

  7. New Insights in Sea Ice Drift Based on Dirty Ice Samples Collected in 2005 by the HOTRAX Expedition

    NASA Astrophysics Data System (ADS)

    Darby, D. A.; Jakobsson, M.; Rigor, I.

    2006-12-01

    Several dirty sea ice samples collected over the rarely visited Alpha Ridge and from other central Arctic Ocean areas are compared to ice-drift back trajectories from International Arctic Buoy Programme. Both the back trajectories and Fe grain fingerprint sources suggest Russian sources near the Laptev Sea (New Siberian Islands), but the Fe grain sources also indicate other Russian sources such as the Kara Sea and even some sources were traced to the northern Arctic Canadian Archipelago. Drift patterns based on back trajectories show that a mix of Russian and N. American sources is possible because the location where the ice was sampled is close to the area where the Trans-Polar Drift carrying Russian ice joins that portion of the Beaufort Gyre moving toward Fram Strait and carrying N. American ice. The Fe grain sources also show that both Russian and N. American ice can occur juxtaposed within very short distances of tens of meters due to mixing of ice floes. This supports earlier findings in the Beaufort Gyre area where Russia floes co-mingled with N. American floes due to repeated separation and rejoining of ice floes. Two dirty ice samples north of Barrow, Alaska indicate a Bering Strait/Chukchi Sea source. The back trajectories in this area do not show any ice originating from any nearshore sources off Alaska nor northern Canada, but only a tight clockwise rotation over the past several years prior to 2005. Thus the Chukchi Sea source is entirely feasible in light of this back- trajectory data. If so this is the first direct evidence of ice in the Beaufort Gyre originating from the Chukchi Sea area.

  8. EOS Aqua AMSR-E Arctic Sea Ice Validation Program: Arctic2003 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus,T.

    2003-01-01

    In March 2003 a coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products to be validated include sea ice concentration, sea ice temperature, and snow depth on sea ice. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. Two additional flights were dedicated to making heat and moisture flux measurements over the St. Lawrence Island polynya to support ongoing air-sea-ice processes studies of Arctic coastal polynyas. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound.

  9. Regional seasonal forecasts of the Arctic sea ice in two coupled climate models

    NASA Astrophysics Data System (ADS)

    Chevallier, Matthieu; Guémas, Virginie; Salas y Mélia, David; Doblas-Reyes, Francisco

    2015-04-01

    The predictive capabilities of two state-of-the-art coupled atmosphere-ocean global climate models (CNRM-CM5.1 and EC-Earth v2.3) in seasonal forecasting of the Arctic sea ice will be presented with a focus on regional skill. 5-month hindcasts of September sea ice area in the Arctic peripherial seas (Barents-Kara seas, Laptev-East Siberian seas, Chukchi sea and Beaufort sea) and March sea ice area in the marginal ice zones (Barents, Greenland, Labrador, Bering and Okhotsk sea) have been produced over the period 1990-2009. Systems mainly differ with respect to the initialization strategy, the ensemble generation techniques and the sea ice components. Predictive skill, assessed in terms of actual and potential predictability, is comparable in the two systems for both summer and winter hindcasts. Most interestingly, the multi-model prediction is often better than individual predictions in several sub-basins, including the Barents sea in the winter and most shelf seas in the summer. Systematic biases are also reduced using the multi-model predictions. Results from this study show that a regional zoom of global seasonal forecasts could be useful for operational needs. This study also show that the multi-model approach may be the step forward in producing accurate and reliable seasonal forecasts based on coupled global climate models.

  10. Trends in sea ice cover within habitats used by bowhead whales in the western Arctic.

    PubMed

    Moore, Sue E; Laidre, Kristin L

    2006-06-01

    We examined trends in sea ice cover between 1979 and 2002 in four months (March, June, September, and November) for four large (approximately 100,000 km2) and 12 small (approximately 10,000 km2) regions of the western Arctic in habitats used by bowhead whales (Balaena mysticetus). Variation in open water with year was significant in all months except March, but interactions between region and year were not. Open water increased in both large and small regions, but trends were weak with least-squares regression accounting for < or =34% of the total variation. In large regions, positive trends in open water were strongest in September. Linear fits were poor, however, even in the East Siberian, Chukchi, and Beaufort seas, where basin-scale analyses have emphasized dramatic sea ice loss. Small regions also showed weak positive trends in open water and strong interannual variability. Open water increased consistently in five small regions where bowhead whales have been observed feeding or where oceanographic models predict prey entrainment, including: (1) June, along the northern Chukotka coast, near Wrangel Island, and along the Beaufort slope; (2) September, near Wrangel Island, the Barrow Arc, and the Chukchi Borderland; and (3) November, along the Barrow Arc. Conversely, there was very little consistent change in sea ice cover in four small regions considered winter refugia for bowhead whales in the northern Bering Sea, nor in two small regions that include the primary springtime migration corridor in the Chukchi Sea. The effects of sea ice cover on bowhead whale prey availability are unknown but can be modeled via production and advection pathways. Our conceptual model suggests that reductions in sea ice cover will increase prey availability along both pathways for this population. This analysis elucidates the variability inherent in the western Arctic marine ecosystem at scales relevant to bowhead whales and contrasts basin-scale depictions of extreme sea ice

  11. Spring Snow Depth on Arctic Sea Ice using the IceBridge Snow Depth Product (Invited)

    NASA Astrophysics Data System (ADS)

    Webster, M.; Rigor, I. G.; Nghiem, S. V.; Kurtz, N. T.; Farrell, S. L.

    2013-12-01

    Snow has dual roles in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from colder air temperatures, slowing its growth. From spring into summer, the albedo of snow determines how much insolation is transmitted through the sea ice and into the underlying ocean, ultimately impacting the progression of the summer ice melt. Knowing the snow thickness and distribution are essential for understanding and modeling sea ice thermodynamics and the surface heat budget. Therefore, an accurate assessment of the snow cover is necessary for identifying its impacts in the changing Arctic. This study assesses springtime snow conditions on Arctic sea ice using airborne snow thickness measurements from Operation IceBridge (2009-2012). The 2012 data were validated with coordinated in situ measurements taken in March 2012 during the BRomine, Ozone, and Mercury EXperiment field campaign. We find a statistically significant correlation coefficient of 0.59 and RMS error of 5.8 cm. The comparison between the IceBridge snow thickness product and the 1937, 1954-1991 Soviet drifting ice station data suggests that the snow cover has thinned by 33% in the western Arctic and 44% in the Beaufort and Chukchi Seas. A rudimentary estimation shows that a thinner snow cover in the Beaufort and Chukchi Seas translates to a mid-December surface heat flux as high as 81 W/m2 compared to 32 W/m2. The relationship between the 2009-2012 thinner snow depth distribution and later sea ice freeze-up is statistically significant, with a correlation coefficient of 0.59. These results may help us better understand the surface energy budget in the changing Arctic, and may improve our ability to predict the future state of the sea ice cover.

  12. Petrographic, mineralogical, and chemical characterization of certain Arctic Alaskan coals from the Cape Beaufort Region

    SciTech Connect

    Rao, P.D.

    1980-01-01

    Coal seams for the Cape Beaufort region of Arctic Northwestern Alaska were sampled by drilling by the US Bureau of Mines, Juneau and the US Geological Survey, Anchorage). Samples from the drill holes were supplied to the Mineral Industry Research Laboratory. These are Cretaceous coals ranging in rank from high volatile bituminous A to B. A total of 48 samples from 18 drill holes intersecting 14 seams were studied. Float-sink separations were made at 1.50 specific gravity for 10 of these samples. Raw coals and float-sink products were characterized for proximate analysis, ultimate analysis, ash fusibility, vitrinite reflectance, coal petrology in reflected light, quantitative determination of mineral matter by x-ray diffraction and infrared spectrophotometry of low temperature ash, major minor, and trace elements by atomic absorption and emission spectrochemical analysis. Influence of beneficiation and geological significance of these characteristics, and organic affinity of trace elements are discussed. A generalized scheme for analysis of coal ash by atomic absorption and emission spectrochemical methods is presented.

  13. Assessment of intrinsic bioremediation of jet fuel contamination in a shallow aquifer, Beaufort, South Carolina

    USGS Publications Warehouse

    Chapelle, Frank; Landmeyer, J.E.; Bradley, P.M.

    1995-01-01

    Field and laboratory studies show that microorganisms indigenous to the ground-water system underlying Tank Farm C, Marine Corps Air Station Beaufort, S.C., degrade petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions, sediments from the shallow aquifer underlying the site mineralized radiolabeled (14C) toluene to 14CO2 with first-order rate constants of about -0.29 per day. Sediments incubated under anaerobic conditions mineralized radiolabeled toluene more slowly, with first-order rate constants of -0.001 per day. Although anaerobic rates of biodegradation are low, they are significant in the hydrologic and geochemical context of the site. Because of low hydraulic conductivities (1.9-9.1 feet per day) and low hydraulic gradients (about 0.004 feet per feet), ground water flows slowly (approximately 20 feet per year) at this site. Furthermore, aquifer sediments contain organic-rich peat that has a high sorptive capacity. Under these conditions, hydrocarbon contaminants have moved no further than 10 feet downgradient of the jet fuel free product. Digital solute-transport simulations, using the range of model parameters measured at the site, show that dissolved contaminants will be completely degraded before they are discharged from the aquifer into adjacent surface-water bodies. These results show that natural attenuation processes are containing the migration of soluble hydrocarbons, and that intrinsic bioremediation is a potentially effective remedial strategy at this site.

  14. Changes in Arctic Melt Season and Implications for Sea Ice Loss

    NASA Technical Reports Server (NTRS)

    Stroeve, J. C.; Markus, T.; Boisvert, L.; Miller, J.; Barrett, A.

    2014-01-01

    The Arctic-wide melt season has lengthened at a rate of 5 days dec-1 from 1979 to 2013, dominated by later autumn freeze-up within the Kara, Laptev, East Siberian, Chukchi and Beaufort seas between 6 and 11 days dec(exp -1). While melt onset trends are generally smaller, the timing of melt onset has a large influence on the total amount of solar energy absorbed during summer. The additional heat stored in the upper ocean of approximately 752MJ m(exp -2) during the last decade, increases sea surface temperatures by 0.5 to 1.5 C and largely explains the observed delays in autumn freeze-up within the Arctic Ocean's adjacent seas. Cumulative anomalies in total absorbed solar radiation from May through September for the most recent pentad locally exceed 300-400 MJ m(exp -2) in the Beaufort, Chukchi and East Siberian seas. This extra solar energy is equivalent to melting 0.97 to 1.3 m of ice during the summer.

  15. Geologic report for the Beaufort Sea planning area, Alaska: regional geology, petroleum geology, environmental geology. Final report

    SciTech Connect

    Craig, J.D.; Sherwood, K.W.; Johnson, P.P.

    1985-12-01

    The 192-page report provides a summary of the geologic framework, hydrocarbon potential, and physical environment of the offshore area tentatively scheduled for Federal OCS (Outer Continental Shelf) Oil and Gas Lease Sale 97. The geologic interpretation is based on high-quality, gridded seismic reflection data and publicly available exploration wells. Seven regional seismic lines, released by Western Geophysical Company for this report, illustrate the geology of the petroleum provinces within the planning area. Hydrocarbon play concepts for large, untested areas of the continental margin off northern Alaska are developed from a detailed analysis of the structural and stratigraphic evolution. Environmental geology is described along with implications for future offshore petroleum activities.

  16. Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Volume 3. Chukchi-Beaufort Sea

    DTIC Science & Technology

    1988-01-01

    8217 j/9 / <’°i 0j 80 / "go90 37C / 0 / 30 30 .0 ’ 0 4 ’ ’ 0 .’’ 0 - 0 0 7 󈧘 300500 0 0o 0 00 So0𔃺 g 0 20302 050 60 7080 90 100 0 0 � 3 0005 0 0

  17. Shore Ice Ride-Up and Pile-Up Features. Part I. Alaska’s Beaufort Sea Coast,

    DTIC Science & Technology

    1983-03-01

    shore- frequent west of Narwhal Island (Fig. B2). However, lines over a number of seasons, along which this may be due to the fact that fewer aerial...obser- Narwhal Island. vations cover tens of thousands of kilometers It appears from historicalreports (Kovacs and Sodhi of shoreline, suggesting an...stresses can be concentrated at ice/shore east of Narwhal Island and of Jeanette and Tapkaluk contact points, thereby increasing the local stress level

  18. 77 FR 38718 - Safety Zone; NOBLE DISCOVERER, Outer Continental Shelf Drillship, Chukchi and/or Beaufort Seas, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-29

    ... significantly reduce the threat of allisions, which could result in oil spills, and releases of natural gas, and...'' W163 28'18.52'' Burger R Posey 6812 OCS-Y-2294 N71 16'06.57'' W163 30'39.44'' Burger S Posey 6762 OCS-Y... local law enforcement officers to make arrests for safety zones established under the PWSA or...

  19. 77 FR 39164 - Safety Zone; KULLUK, Outer Continental Shelf Mobile Offshore Drilling Unit (MODU), Beaufort Sea, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... anchor system on the seafloor. The KULLUK will have an anchor radius of 3,117 ft (950 m) for the Sivulliq... outer edge of the anchor spread. The anchor spread, which radiates from the center of the KULLUK, may pose a fouling hazard to any vessel attempting to anchor within the anchor spread. Fouling of...

  20. 77 FR 10711 - Safety Zone; KULLUK, Outer Continental Shelf Mobile Offshore Drilling Unit (MODU), Beaufort Sea, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... under the hull to the ] anchor system on the seafloor. The KULLUK will have an anchor radius of 3,117 ft... buoys will delineate the outer edge of the anchor spread. The anchor spread, which radiates from the... spread. Fouling of the KULLUK anchor lines may endanger the drillship, its 108 persons onboard, the...

  1. Navy Tactical Applications Guide, Volume 8 Part 2: Arctic - East Siberian/Chukchi/Beaufort Seas. Weather Analysis and Forecast Applications

    DTIC Science & Technology

    1992-12-01

    respond realistically to Arctic conditions. Hope for improvement lies in employing new high resolution numerical models with better planetary... new analysis and forecast techniques, specifically adapted to this region. This volume has been developed to illustrate, with high resolution...an important role leading to more rapid intensification. This is certainly not a new finding, but is important to emphasize. These jet streaks

  2. Geological, geochemical, and operational summary, aurora well, OCS Y-0943-1, Beaufort Sea, Alaska. Final report

    SciTech Connect

    Paul, L.E.; Choromanski, D.R.; Turner, R.F.; Flett, T.O.; Paul, L.E.

    1994-01-01

    The Aurora well is located just off the coast of the Arctic National Wildlife Refuge (ANWR). The well was spudded November 2, 1987, in 68 ft of water and plugged and abandoned 286 days later on August 30, 1988, after drilling to a total depth (TD) of 18,325 ft below the Kelly Bushing (RKB). The report presents our interpretations of the geologic and geochemical information collected from the Aurora well. Additionally, a significant section of the report is devoted to the operational aspects of drilling the Aurora well.

  3. Relating Regional Arctic Sea Ice and climate extremes over Europe

    NASA Astrophysics Data System (ADS)

    Ionita-Scholz, Monica; Grosfeld, Klaus; Lohmann, Gerrit; Scholz, Patrick

    2016-04-01

    The potential increase of temperature extremes under climate change is a major threat to society, as temperature extremes have a deep impact on environment, hydrology, agriculture, society and economy. Hence, the analysis of the mechanisms underlying their occurrence, including their relationships with the large-scale atmospheric circulation and sea ice concentration, is of major importance. At the same time, the decline in Arctic sea ice cover during the last 30 years has been widely documented and it is clear that this change is having profound impacts at regional as well as planetary scale. As such, this study aims to investigate the relation between the autumn regional sea ice concentration variability and cold winters in Europe, as identified by the numbers of cold nights (TN10p), cold days (TX10p), ice days (ID) and consecutive frost days (CFD). We analyze the relationship between Arctic sea ice variation in autumn (September-October-November) averaged over eight different Arctic regions (Barents/Kara Seas, Beaufort Sea, Chukchi/Bering Seas, Central Arctic, Greenland Sea, Labrador Sea/Baffin Bay, Laptev/East Siberian Seas and Northern Hemisphere) and variations in atmospheric circulation and climate extreme indices in the following winter season over Europe using composite map analysis. Based on the composite map analysis it is shown that the response of the winter extreme temperatures over Europe is highly correlated/connected to changes in Arctic sea ice variability. However, this signal is not symmetrical for the case of high and low sea ice years. Moreover, the response of temperatures extreme over Europe to sea ice variability over the different Arctic regions differs substantially. The regions which have the strongest impact on the extreme winter temperature over Europe are: Barents/Kara Seas, Beaufort Sea, Central Arctic and the Northern Hemisphere. For the years of high sea ice concentration in the Barents/Kara Seas there is a reduction in the number

  4. CryoSat-2 Estimates of Sea Ice Freeboard in the Greenland Sea of Arctic

    NASA Astrophysics Data System (ADS)

    Zhang, S.

    2015-12-01

    Arctic region is one of the most important parts that contribute to the global climate system. As an important climatic indicator, sea ice has also undergone dramatic changes. Due to the limitations of poor geographical conditions and a lack of in-situ observations, knowledge about Arctic sea ice has not been explored well for a long time, furthermore it is especial difficult to get a high quality of Arctic Sea ice thickness information.Equipped with a Ku-band SIRAL, CryoSat-2 has been launched in 2010 as an important European Space Agency Earth Explorer Opportunity mission. CryoSat-2 has the advantage of measuring the thickness of polar sea ice and monitoring changes in the ice sheets that blanket Greenland and Antarctica with high precision. In this paper, the CryoSat-2/SIRAL radar altimeter data were used to retrieve the sea ice thickness in the Greenland Sea, Arctic, validated with the Ice, Cloud, and Land Elevation (ICESat) laser altimeter measurements from National Aeronautics and Space Administration (NASA) and Beaufort Gyre Experiment Program (BGEP) Upward Looking Sonar (ULS) measurements. Results show that the sea ice freeboard in Greenland Sea has a remarkable seasonal variation and presents an evident regional characteristics. As it show below, during the frozen season in autumn and winter the sea ice freeboard concentrated in around 0.23m , the average freeboard in Greenland Sea in June decreased to around 0.18m, the minimum freeboard 0.12m appeared in September. In the Western Greenland Sea near the Greenland and the Fram Strait with higher-latitude where multi-year ice occupy most has a larger freeboard around 0.3m in winter. In the south-eastern Greenland Sea with lower-latitude and shallow sea water, the freeboard composed by first-year ice concentrated in around 0.1m in winter. At the same time, the sea ice area also had seasonal variations, its maximum was in January and March, and minimum was in September.

  5. Subsea ice-bearing permafrost on the U.S. Beaufort Margin: 2. Borehole constraints

    USGS Publications Warehouse

    Ruppel, Carolyn D.; Herman, Bruce M.; Brothers, Laura L.; Hart, Patrick E.

    2016-01-01

    Borehole logging data from legacy wells directly constrain the contemporary distribution of subsea permafrost in the sedimentary section at discrete locations on the U.S. Beaufort Margin and complement recent regional analyses of exploration seismic data to delineate the permafrost's offshore extent. Most usable borehole data were acquired on a ∼500 km stretch of the margin and within 30 km of the contemporary coastline from north of Lake Teshekpuk to nearly the U.S.-Canada border. Relying primarily on deep resistivity logs that should be largely unaffected by drilling fluids and hole conditions, the analysis reveals the persistence of several hundred vertical meters of ice-bonded permafrost in nearshore wells near Prudhoe Bay and Foggy Island Bay, with less permafrost detected to the east and west. Permafrost is inferred beneath many barrier islands and in some nearshore and lagoonal (back-barrier) wells. The analysis of borehole logs confirms the offshore pattern of ice-bearing subsea permafrost distribution determined based on regional seismic analyses and reveals that ice content generally diminishes with distance from the coastline. Lacking better well distribution, it is not possible to determine the absolute seaward extent of ice-bearing permafrost, nor the distribution of permafrost beneath the present-day continental shelf at the end of the Pleistocene. However, the recovery of gas hydrate from an outer shelf well (Belcher) and previous delineation of a log signature possibly indicating gas hydrate in an inner shelf well (Hammerhead 2) imply that permafrost may once have extended across much of the shelf offshore Camden Bay.

  6. Subsea ice-bearing permafrost on the U.S. Beaufort Margin: 2. Borehole constraints

    NASA Astrophysics Data System (ADS)

    Ruppel, Carolyn D.; Herman, Bruce M.; Brothers, Laura L.; Hart, Patrick E.

    2016-11-01

    Borehole logging data from legacy wells directly constrain the contemporary distribution of subsea permafrost in the sedimentary section at discrete locations on the U.S. Beaufort Margin and complement recent regional analyses of exploration seismic data to delineate the permafrost's offshore extent. Most usable borehole data were acquired on a ˜500 km stretch of the margin and within 30 km of the contemporary coastline from north of Lake Teshekpuk to nearly the U.S.-Canada border. Relying primarily on deep resistivity logs that should be largely unaffected by drilling fluids and hole conditions, the analysis reveals the persistence of several hundred vertical meters of ice-bonded permafrost in nearshore wells near Prudhoe Bay and Foggy Island Bay, with less permafrost detected to the east and west. Permafrost is inferred beneath many barrier islands and in some nearshore and lagoonal (back-barrier) wells. The analysis of borehole logs confirms the offshore pattern of ice-bearing subsea permafrost distribution determined based on regional seismic analyses and reveals that ice content generally diminishes with distance from the coastline. Lacking better well distribution, it is not possible to determine the absolute seaward extent of ice-bearing permafrost, nor the distribution of permafrost beneath the present-day continental shelf at the end of the Pleistocene. However, the recovery of gas hydrate from an outer shelf well (Belcher) and previous delineation of a log signature possibly indicating gas hydrate in an inner shelf well (Hammerhead 2) imply that permafrost may once have extended across much of the shelf offshore Camden Bay.

  7. Changes in the Canada Basin: Results From Beaufort Gyre Observing Program/Joint Ocean Ice Studies Expeditions, 2003-2014.

    NASA Astrophysics Data System (ADS)

    Williams, W. J.; Proshutinsky, A. Y.; Krishfield, R. A.; Timmermans, M. L. E.; Yamamoto-Kawai, M.; Li, W.; Zimmermann, S.; Hutchings, J.; McLaughlin, F.; Carmack, E.

    2014-12-01

    Annual expeditions, that make use of ships, moorings and ice tethered platforms, have monitored oceanographic conditions in the Beaufort Gyre Region of the Canada Basin since 2003. These basin-wide surveys, together with available earlier data, show linkages between the physical, geo-chemical and ecosystem components during a period of rapid change, largely forced by increased multi-year ice melt and a prolonged anticyclonic phase of the Arctic Ocean circulation. The resulting Ekman convergence has led to a progressive accumulation of river and ice-melt-derived freshwater within the gyre, an increase in surface stratification and depression of the halocline. These changes in physical state have led to a decrease in aragonite saturation state, a deepening of the top of the nutricline and subsurface chlorophyll maximum and a shift in phytoplankton size spectra. Recent years have shown a slight relaxation of the Beaufort Gyre, in addition to large variation in ice cover, leading to informed speculation that the gyre may now be poised to release some of its accumulated freshwater as a salinity anomaly into the global system.

  8. Stability Zone of Natural Gas Hydrates in a Permafrost-Bearing Region of the Beaufort-Mackenzie Basin: Study of a Feasible Energy Source (Geological Survey of Canada Contribution No.1999275)

    SciTech Connect

    Majorowicz, J. A. Hannigan, P. K.

    2000-03-15

    Analysis of geological and geophysical data from 150 wells in the Beaufort-Mackenzie region(study area between 68 deg. 30'-70 deg. 00'N and 131 deg. -39 deg. W) led to reinterpretation of the depth of methane hydrate stability and construction of the first contour maps displaying thickness of hydrate stability zones as well as hydrate stability zone thicknesses below permafrost. Calculations were based on construction of temperature-depth profiles incorporating regional heat-flow values, temperature at the base of ice-bearing permafrost, and models relating thermal conductivity with depth. Data analysis indicates the presence and extent of the methane hydrate stability zone is related mainly to the history of permafrost development and less so by the relatively small regional variations of temperature gradients. Analysis of well logs and other indicators in conjunction with knowledge of the hydrate stability zone allows reevaluation of the location of possible gas hydrate occurrences. Log analysis indicates that in the onshore and shallow sea area of the Beaufort-Mackenzie Basin, methane hydrate occurs in 27 wells. Fifteen of these locations coincides with underlying conventional hydrocarbon occurrences. Previous analyses place some of the hydrate occurrences at greater depths than proposed for the methane hydrate stability zone described in this study. Interpretation of geological cross sections reveals that hydrates are related mainly to sandy deltaic and delta-plain deposits in Iperk, Kugmallit, and Reindeer sequences although additional hydrate picks have been inferred in other sequences, such as Richards. Overlying permafrost may act as seal for hydrate accumulations; however, the thickness of permafrost and its related hydrate stability zone fluctuated during geological time. It is interpreted that only in the last tens of thousand of years (i.e., Sangamonian to Holocene), conditions for hydrates changed from nonstable to stable. During Early and Late

  9. Arctic and Antarctic Sea Ice Changes and Impacts (Invited)

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.

    2013-12-01

    The extent of springtime Arctic perennial sea ice, important to preconditioning summer melt and to polar sunrise photochemistry, continues its precipitous reduction in the last decade marked by a record low in 2012, as the Bromine, Ozone, and Mercury Experiment (BROMEX) was conducted around Barrow, Alaska, to investigate impacts of sea ice reduction on photochemical processes, transport, and distribution in the polar environment. In spring 2013, there was further loss of perennial sea ice, as it was not observed in the ocean region adjacent to the Alaskan north coast, where there was a stretch of perennial sea ice in 2012 in the Beaufort Sea and Chukchi Sea. In contrast to the rapid and extensive loss of sea ice in the Arctic, Antarctic sea ice has a trend of a slight increase in the past three decades. Given the significant variability in time and in space together with uncertainties in satellite observations, the increasing trend of Antarctic sea ice may arguably be considered as having a low confidence level; however, there was no overall reduction of Antarctic sea ice extent anywhere close to the decreasing rate of Arctic sea ice. There exist publications presenting various factors driving changes in Arctic and Antarctic sea ice. After a short review of these published factors, new observations and atmospheric, oceanic, hydrological, and geological mechanisms contributed to different behaviors of sea ice changes in the Arctic and Antarctic are presented. The contribution from of hydrologic factors may provide a linkage to and enhance thermal impacts from lower latitudes. While geological factors may affect the sensitivity of sea ice response to climate change, these factors can serve as the long-term memory in the system that should be exploited to improve future projections or predictions of sea ice changes. Furthermore, similarities and differences in chemical impacts of Arctic and Antarctic sea ice changes are discussed. Understanding sea ice changes and

  10. Spatial and temporal variations in the age structure of Arctic sea ice

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.

    2005-01-01

    Spatial and temporal variations in the age structure of Arctic sea ice are investigated using a new reverse chronology algorithm that tracks ice-covered pixels to their location and date of origin based on ice motion and concentration data. The Beaufort Gyre tends to harbor the oldest (>10 years old) sea ice in the western Arctic while direct ice advection pathways toward the Transpolar Drift Stream maintain relatively young (10 years old (10+ year age class) were observed during 1989-2003. Since the mid-1990s, losses to the 10+ year age class lacked compensation by recruitment due to a prior depletion of all mature (6-10 year) age classes. Survival of the 1994 and 1996-1998 sea ice generations reestablished most mature age classes, and thereby the potential to increase extent of the 10+ year age class during the mid-2000s.

  11. Hydrographic patterns in microbial communities in the density stratified Alaska Beaufort Shelf

    NASA Astrophysics Data System (ADS)

    Hamdan, L. J.; Gillevet, P. M.; Sikaroodi, M.; Greinert, J.; Treude, T.; Coffin, R. B.

    2011-12-01

    Although similar microbial communities have been observed globally in methane charged sediments, the mechanism of their dispersal is unknown. The ocean may be a physical barrier for dispersal of anaerobic microorganisms typically found in methane seeps. However, it is possible that bottom layers act as distribution conduits for dormant cells to locations where geochemical conditions would allow them to flourish. The Alaska Beaufort Shelf (ABS) was used to stage a preliminary study of dispersal patterns of microbial communities from methane influenced waters and sediments. During September 2009 three density stratified water masses were present on the ABS, including a low salinity Arctic surface layer, an intermediate Pacific layer, and a deep, cold and saline Atlantic layer. Microbial community composition was studied in each water mass and in underlying sediments to determine the influence of water mass on sediment community structure. Sediment cores were obtained using a piston corer. Water samples were retrieved using a CTD rosette, and hydrodynamic data (e.g., salinity, temperature, density, dissolved oxygen) were acquired simultaneously. Methane concentrations were measured using a GC-FID. Community composition was surveyed using Multitag Pyrosequencing (MTPS) and Length Heterogeneity-PCR (LH-PCR) by amplification of hypervariable regions of the archaeal and bacterial SSUrRNA. MTPS data were processed using the QIIME pipeline, and taxonomy was assigned using the RDP classifier. The Unifrac metric and multidimensional scaling analysis was used to determine similarity patterns. Distinct bacterial communities were evident in the three water masses. Sequences related to the SAR11 clade were highly abundant in the Arctic layer. Gammaproteobacteria related to the Thiotrichales were abundant in Pacific and Atlantic layers. Archaeal water column communities were relatively homogeneous, and unidentified Euryarchaeota dominated all three water masses. Microbial

  12. Evaluation of Arctic Sea Ice Thickness Simulated by AOMIP Models

    NASA Technical Reports Server (NTRS)

    Johnson, Mark; Proshutinsky, Andrey; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nimolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; de Cuevas, Beverly

    2011-01-01

    We compare results from six AOMIP model simulations with estimates of sea ice thickness obtained from ICESat, moored and submarine-based upward looking sensors, airborne electromagnetic measurements and drill holes. Our goal is to find patterns of model performance to guide model improvement. The satellite data is pan-arctic from 2004-2008, ice-draft data is from moored instruments in Fram Strait, the Greenland Sea and the Beaufort Sea from 1992-2008 and from submarines from 1975-2000. The drill hole data are from the Laptev and East Siberian marginal seas from 1982-1986 and from coastal stations from 1998-2009. While there are important caveats when comparing modeled results with measurements from different platforms and time periods such as these, the models agree well with moored ULS data. In general, the AOMIP models underestimate the thickness of measured ice thicker than about 2 m and overestimate thickness of ice thinner than 2 m. The simulated results are poor over the fast ice and marginal seas of the Siberian shelves. Averaging over all observational data sets, the better correlations and smaller differences from observed thickness are from the ECCO2 and UW models.

  13. Arctic Low Cloud Changes as Observed by MISR and CALIOP: Implication for the Enhanced Autumnal Warming and Sea Ice Loss

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Lee, Jae N.

    2012-01-01

    Retreat of Arctic sea ice extent has led to more evaporation over open water in summer and subsequent cloud changes in autumn. Studying recent satellite cloud data over the Arctic Ocean, we find that low (0.5-2 km) cloud cover in October has been increasing significantly during 2000-2010 over the Beaufort and East Siberian Sea (BESS). This change is consistent with the expected boundary-layer cloud response to the increasing Arctic evaporation accumulated during summer. Because low clouds have a net warming effect at the surface, October cloud increases may be responsible for the enhanced autumnal warming in surface air temperature, which effectively prolong the melt season and lead to a positive feedback to Arctic sea ice loss. Thus, the new satellite observations provide a critical support for the hypothesized positive feedback involving interactions between boundary-layer cloud, water vapor, temperature and sea ice in the Arctic Ocean.

  14. The footprints of 16 year trends of Arctic springtime cloud and radiation properties on September sea ice retreat

    NASA Astrophysics Data System (ADS)

    Huang, Yiyi; Dong, Xiquan; Xi, Baike; Dolinar, Erica K.; Stanfield, Ryan E.

    2017-02-01

    The most prominent September Arctic sea ice decline over the period of 2000-2015 occurs over the Siberian Sea, Laptev Sea, and Kara Sea. The satellite observed and retrieved sea ice concentration (SIC) and cloud/radiation properties over the Arctic (70°-90°N) have been used to investigate the impact of springtime cloud and radiation properties on September SIC variation. Positive trends of cloud fractions, cloud water paths, and surface downward longwave flux at the surface over the September sea ice retreat areas are found over the period of 1 March to 14 May, while negative trends are found over the period of 15 May to 28 June. The spatial distributions of correlations between springtime cloud/radiation properties and September SIC have been calculated, indicating that increasing cloud fractions and downward longwave flux during springtime tend to enhance sea ice melting due to strong cloud warming effect. Surface downward and upward shortwave fluxes play an important role from May to June when the onset of sea ice melting occurs. The comparison between linearly detrended and nondetrended of each parameter indicates that significant impact of cloud and radiation properties on September sea ice retreat occurs over the Chukchi/Beaufort Sea at interannual time scale, especially over the period of 31 March to 29 April, while strongest climatological trends are found over the Laptev/Siberian Sea.

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

    PubMed

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

    2010-07-15

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

  16. Revisiting Observations of Arctic Sea-ice Motion and Deformation To Investigate Bounds of Sea-ice Variability.

    NASA Astrophysics Data System (ADS)

    Heil, P.

    The Arctic sea ice is an important part of the northern polar climate system. Individual records of sea-ice drift in the Arctic were obtained through the last century. Observa- tions with high spatial or temporal coverage start in the 1970's when remote observa- tions of sea-ice motion are available from satellite-based instruments and in situ from drifting buoys. In the climatology of Arctic sea-ice drift the clockwise Beaufort Gyre, a northward motion off the Siberian Coast, and a south-eastward drift from the North Pole towards Fram Strait, have been identified. During recent decades this picture of Arctic ice motion has shifted away from the baseline state in response to changed at- mospheric conditions. Here we investigate high-resolution time-series of ice motion derived from IABP drifting buoys to identify further patterns of preferred ice motion in the Arctic. These can be associated with atmospheric regimes by correlating the two- dimensional variance of the buoy-derived ice velocities with the horizontal gradient of the mean sea-level pressure. Changes in the spatial pattern of regional meander coeffi- cients for the sea-ice motion provide further evidence for repeated transitions between patterns of ice motion in dependence to the atmospheric forcing. This is supported by dynamic frequency spectra of sea-ice divergence, which suggest damping of subdaily deformation cycles during low AO years. For regions with persistent buoy coverage (e.g., the western Arctic) time-series of sea-ice motion and deformation characteris- tics have been constructed. The identification of a dominant spatial pattern of sea-ice motion and deformation in response to changing atmospheric forcing is then used to explain the variability seen in Arctic ice extent and volume.

  17. Comparison of Arctic sea ice thickness and snow depth estimates from CFSR with in situ observations

    NASA Astrophysics Data System (ADS)

    Sato, Kazutoshi; Inoue, Jun

    2017-03-01

    Sea ice growth is modulated by snow cover, and understanding this relationship requires an accurate determination of snow depth. However, a lack of in situ measurements complicates understanding of the interaction of snow depth with sea ice growth. We evaluated the accuracy of Climate Forecast System Reanalysis (CFSR) data for snow depth and sea ice thickness to study the change of snow depth on Arctic sea ice. We compared CFSR and snow depth data from 35 drifting buoys in 2002-2013. The mean annual cycle of CFSR snow depth corresponded well with the buoy data. However, the CFSR data had a positive bias during winter (10-20 cm) and spring (5-25 cm), and a negative bias during summer (-25-0 cm) and autumn (-5-10 cm). The CFSR data showed increases in snow depth from 1979 to 2013 over the Beaufort and northern Chukchi Seas during November. Significant positive trends in precipitation contributed to increased snow depth in this region when sea ice began to form. The results of model experiments using a 1-D thermodynamic sea ice model in the CFSR demonstrated a recommended value of snow thermal conductivity (0.16 W m-1 K-1), and suggested that the sea ice growth was effectively restricted by the recent increase in snow depth on thin ice during winter.

  18. 75 FR 13654 - Use of Foreign-Flag Anchor Handling Vessels in the Beaufort Sea or Chukchi Sea Adjacent to Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-22

    ....-flag vessels are not suitable or reasonably available and if the lessee has entered into a binding contract to obtain and employ an eligible vessel. The lessee has entered into a long term time charter...

  19. Salish Sea

    EPA Pesticide Factsheets

    The Health of the Salish Sea Report is a collaboration between EPA and Environment Canada to examine the health of the Salish Sea ecosystem in Washington and British Columbia, encompassing the Puget Sound and Georgia Basin.

  20. Dipole Anomaly in the Winter Arctic Atmosphere and Its Association with Sea Ice Motion.

    NASA Astrophysics Data System (ADS)

    Wu, Bingyi; Wang, Jia; Walsh, John E.

    2006-01-01

    This paper identified an atmospheric circulation anomaly dipole structure anomaly in the Arctic atmosphere and its relationship with winter sea ice motion, based on the International Arctic Buoy Program (IABP) dataset (1979 98) and datasets from the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) for the period 1960 2002. The dipole anomaly corresponds to the second-leading mode of EOF of monthly mean sea level pressure (SLP) north of 70°N during the winter season (October March) and accounts for 13% of the variance. One of its two anomalous centers is stably occupied between the Kara Sea and Laptev Sea; the other is situated from the Canadian Archipelago through Greenland extending southeastward to the Nordic seas. The dipole anomaly differs from one described in other papers that can be attributed to an eastward shift of the center of action of the North Atlantic Oscillation. The finding shows that the dipole anomaly also differs from the “Barents Oscillation” revealed in a study by Skeie. Since the dipole anomaly shows a strong meridionality, it becomes an important mechanism to drive both anomalous sea ice exports out of the Arctic Basin and cold air outbreaks into the Barents Sea, the Nordic seas, and northern Europe.When the dipole anomaly remains in its positive phase, that is, negative SLP anomalies appear between the Kara Sea and the Laptev Sea with concurrent positive SLP over from the Canadian Archipelago extending southeastward to Greenland, there are large-scale changes in the intensity and character of sea ice transport in the Arctic basin. The significant changes include a weakening of the Beaufort gyre, an increase in sea ice export out of the Arctic basin through Fram Strait and the northern Barents Sea, and enhanced sea ice import from the Laptev Sea and the East Siberian Sea into the Arctic basin. Consequently, more sea ice appears in the Greenland and the Barents Seas during the

  1. Red Sea

    Atmospheric Science Data Center

    2013-04-16

    article title:  The Red Sea     View Larger Image ... 2000. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because the blooms of a type of ... 2000 - The Red Sea between the East Africa coast and Saudi Arabian peninsula. project:  MISR category:  ...

  2. Bering Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The skies of the Bering Sea were relatively clear again in this SeaWiFS image showing a band of aquamarine colored water. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  3. Bering Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Much of the Bering Sea is clear in this SeaWiFS image. The large expanse of bright aquamarine water is clearly visible. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  4. Arctic sea surface height variability and change from satellite radar altimetry and GRACE, 2003-2014

    NASA Astrophysics Data System (ADS)

    Armitage, Thomas W. K.; Bacon, Sheldon; Ridout, Andy L.; Thomas, Sam F.; Aksenov, Yevgeny; Wingham, Duncan J.

    2016-06-01

    Arctic sea surface height (SSH) is poorly observed by radar altimeters due to the poor coverage of the polar oceans provided by conventional altimeter missions and because large areas are perpetually covered by sea ice, requiring specialized data processing. We utilize SSH estimates from both the ice-covered and ice-free ocean to present monthly estimates of Arctic Dynamic Ocean Topography (DOT) from radar altimetry south of 81.5°N and combine this with GRACE ocean mass to estimate steric height. Our SSH and steric height estimates show good agreement with tide gauge records and geopotential height derived from Ice-Tethered Profilers. The large seasonal cycle of Arctic SSH (amplitude ˜5 cm) is dominated by seasonal steric height variation associated with seasonal freshwater fluxes, and peaks in October-November. Overall, the annual mean steric height increased by 2.2 ± 1.4 cm between 2003 and 2012 before falling to circa 2003 levels between 2012 and 2014 due to large reductions on the Siberian shelf seas. The total secular change in SSH between 2003 and 2014 is then dominated by a 2.1 ± 0.7 cm increase in ocean mass. We estimate that by 2010, the Beaufort Gyre had accumulated 4600 km3 of freshwater relative to the 2003-2006 mean. Doming of Arctic DOT in the Beaufort Sea is revealed by Empirical Orthogonal Function analysis to be concurrent with regional reductions in the Siberian Arctic. We estimate that the Siberian shelf seas lost ˜180 km3 of freshwater between 2003 and 2014, associated with an increase in annual mean salinity of 0.15 psu yr-1. Finally, ocean storage flux estimates from altimetry agree well with high-resolution model results, demonstrating the potential for altimetry to elucidate the Arctic hydrological cycle.

  5. Aircraft active and passive microwave validation of sea ice concentration from the Defense Meteorological Satellite Program special sensor microwave imager

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Crawford, J. P.; Drinkwater, M. R.; Eppler, D. T.; Farmer, L. D.; Jentz, R. R.; Wackerman, C. C.

    1991-01-01

    Results are presented of a series of coordinate special sensor microwave imager (SSM/I) underflights that were carried out during March 1988 with NASA and Navy aircraft over portions of the Bering, Beaufort, and Chukchi seas. NASA DC-8 AMMR data from Bering Sea ice edge crossings were used to verify that the ice edge location, defined as the position of the initial ice bands encountered by the aircraft, corresponds to an SSM/I ice concentration of 15 percent. Direct comparison of SSM/I and aircraft ice concentrations for regions having at least 80 percent aircraft coverage reveals that the SSM/I total ice concentration is lower on average by 2.4 +/-2.4 percent. For multiyear ice, NASA and Navy flights across the Beaufort and Chukchi seas show that the SSM/I algorithm correctly maps the large-scale distribution of multiyear ice: the zone of first-year ice off the Alaskan coast, the large areas of mixed first-year and multiyear ice, and the region of predominantly multiyear ice north of the Canadian archipelago.

  6. Sea ice motion measurements from Seasat SAR images

    NASA Technical Reports Server (NTRS)

    Leberl, F.; Raggam, J.; Elachi, C.; Campbell, W. J.

    1983-01-01

    Data from the Seasat synthetic aperture radar (SAR) experiment are analyzed in order to determine the accuracy of this information for mapping the distribution of sea ice and its motion. Data from observations of sea ice in the Beaufort Sea from seven sequential orbits of the satellite were selected to study the capabilities and limitations of spaceborne radar application to sea-ice mapping. Results show that there is no difficulty in identifying homologue ice features on sequential radar images and the accuracy is entirely controlled by the accuracy of the orbit data and the geometric calibration of the sensor. Conventional radargrammetric methods are found to serve well for satellite radar ice mapping, while ground control points can be used to calibrate the ice location and motion measurements in the cases where orbit data and sensor calibration are lacking. The ice motion was determined to be approximately 6.4 + or - 0.5 km/day. In addition, the accuracy of pixel location was found over land areas. The use of one control point in 10,000 sq km produced an accuracy of about + or 150 m, while with a higher density of control points (7 in 1000 sq km) the location accuracy improves to the image resolution of + or - 25 m. This is found to be applicable for both optical and digital data.

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

    USGS Publications Warehouse

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

    1999-01-01

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

  8. Coastal erosion vs riverline sediment discharge in the Arctic shelfx seas

    USGS Publications Warehouse

    Rachold, V.; Grigoriev, M.N.; Are, F.E.; Solomon, Sean C.; Reimnitz, E.; Kassens, H.; Antonow, M.

    2000-01-01

    This article presents a comparison of sediment input by rivers and by coastal erosion into both the Laptev Sea and the Canadian Beaufort Sea (CBS). New data on coastal erosion in the Laptev Sea, which are based on field measurements and remote sensing information and existing data on coastal erosion in the CBS as well as riverine sediment discharge into both the Laptev Sea and the CBS are included. Strong regional differences in the percentages of coastal ero- sion and riverine sediment supply are observed. The CBS is dominated by the riverine sediment discharge (64.45x106 t a-1) mainly of the Mackenzie River. which is the largest single source of sediments in the Arctic. Riverine sediment discharge into the Laptev Sea amounts to 24.10x106 t a-1, more than 70% of which are related to the Lena River. In comparison with the CBS. the Laptev Sea coast on average delivers approximately twice as much sediment mass per kilometer, a result of higher erosion rates due to higher cliffs and seasonal ice melting. In the Laptev Sea sediment input by coastal erosion (58.4x106 t a-1) is therefore more important than in the CBS and the ratio between riverine and coastal sediment input amounts to 0.4. Coastal erosion supplying 5.6x106 t a-1 is less significant for the sediment budget of the CBS where riverine sediment discharge exceeds coastal sediment input by a factor of ca. 10.

  9. Geology and mineral resources of the Florence, Beaufort, Rocky Mount, and Norfolk 1/sup 0/ x 2/sup 0/ NTMS quadrangles. National Uranium Resource Evaluation program

    SciTech Connect

    Harris, W.B.

    1982-08-01

    This document provides geologic and mineral resources data for previously-issued Savannah River Laboratory hydrogeochemical and stream sediment reports of the Beaufort, Florence, Norfolk, and Rocky Mount 1/sup 0/ x 2/sup 0/ National Topographic Map Series quadrangles in the southeastern United States. This report is issued in draft form, without detailed technical and copy editing. This was done to make the report available to the public before the end of the National Uranium Resource Evaluation program.

  10. Simulation of the interannual variability of the wind-driven Arctic sea-ice cover during 1958-1998

    NASA Astrophysics Data System (ADS)

    Arfeuille, G.; Mysak, L. A.; Tremblay, L.-B.

    A thermodynamic-dynamic sea-ice model based on a granular material rheology developed by Tremblay and Mysak is used to study the interannual variability of the Arctic sea-ice cover during the 41-year period 1958-98. Monthly wind stress forcing derived from the National Centers for Environmental Prediction (NCEP) Reanalysis data is used to produce the year-to-year variations in the sea-ice circulation and thickness. We focus on analyzing the variability of the sea-ice volume in the Arctic Basin and the subsequent changes in sea-ice export into the Greenland Sea via Fram Strait. The relative contributions of the Fram Strait sea-ice thickness and velocity anomalies to the sea-ice export anomalies are first investigated, and the former is shown to be particularly important during several large export events. The sea-ice export anomalies for these events are next linked to prior sea-ice volume anomalies in the Arctic Basin. The origin and evolution of the sea-ice volume anomalies are then related to the sea-ice circulation and atmospheric forcing patterns in the Arctic. Large sea-ice export anomalies are generally preceded by large volume anomalies formed along the East Siberian coast due to anomalous winds which occur when the Arctic High is centered closer than usual to this coastal area. When the center of this High relocates over the Beaufort Sea and the Icelandic Low extends far into the Arctic Basin, the ice volume anomalies are transported to the Fram Strait region via the Transpolar Drift Stream. Finally, the link between the sea-ice export and the North Atlantic Oscillation (NAO) index is briefly discussed. The overall results from this study show that the Arctic Basin and its ice volume anomalies must be considered in order to fully understand the export through Fram Strait.

  11. Subsea ice-bearing permafrost on the U.S. Beaufort Margin: 1. Minimum seaward extent defined from multichannel seismic reflection data

    USGS Publications Warehouse

    Brothers, Laura; Herman, Bruce M.; Hart, Patrick E.; Ruppel, Carolyn D.

    2016-01-01

    Subsea ice-bearing permafrost (IBPF) and associated gas hydrate in the Arctic have been subject to a warming climate and saline intrusion since the last transgression at the end of the Pleistocene. The consequent degradation of IBPF is potentially associated with significant degassing of dissociating gas hydrate deposits. Previous studies interpreted the distribution of subsea permafrost on the U.S. Beaufort continental shelf based on geographically sparse data sets and modeling of expected thermal history. The most cited work projects subsea permafrost to the shelf edge (∼100 m isobath). This study uses a compilation of stacking velocity analyses from ∼100,000 line-km of industry-collected multichannel seismic reflection data acquired over 57,000 km2 of the U.S. Beaufort shelf to delineate continuous subsea IBPF. Gridded average velocities of the uppermost 750 ms two-way travel time range from 1475 to 3110 m s−1. The monotonic, cross-shore pattern in velocity distribution suggests that the seaward extent of continuous IBPF is within 37 km of the modern shoreline at water depths < 25 m. These interpretations corroborate recent Beaufort seismic refraction studies and provide the best, margin-scale evidence that continuous subsea IBPF does not currently extend to the northern limits of the continental shelf.

  12. Subsea ice-bearing permafrost on the U.S. Beaufort Margin: 1. Minimum seaward extent defined from multichannel seismic reflection data

    NASA Astrophysics Data System (ADS)

    Brothers, Laura L.; Herman, Bruce M.; Hart, Patrick E.; Ruppel, Carolyn D.

    2016-11-01

    Subsea ice-bearing permafrost (IBPF) and associated gas hydrate in the Arctic have been subject to a warming climate and saline intrusion since the last transgression at the end of the Pleistocene. The consequent degradation of IBPF is potentially associated with significant degassing of dissociating gas hydrate deposits. Previous studies interpreted the distribution of subsea permafrost on the U.S. Beaufort continental shelf based on geographically sparse data sets and modeling of expected thermal history. The most cited work projects subsea permafrost to the shelf edge (˜100 m isobath). This study uses a compilation of stacking velocity analyses from ˜100,000 line-km of industry-collected multichannel seismic reflection data acquired over 57,000 km2 of the U.S. Beaufort shelf to delineate continuous subsea IBPF. Gridded average velocities of the uppermost 750 ms two-way travel time range from 1475 to 3110 m s-1. The monotonic, cross-shore pattern in velocity distribution suggests that the seaward extent of continuous IBPF is within 37 km of the modern shoreline at water depths < 25 m. These interpretations corroborate recent Beaufort seismic refraction studies and provide the best, margin-scale evidence that continuous subsea IBPF does not currently extend to the northern limits of the continental shelf.

  13. Digital terrain mapping of the underside of sea ice from a small AUV

    NASA Astrophysics Data System (ADS)

    Wadhams, P.; Doble, M. J.

    2008-01-01

    In April 2007 the first three-dimensional digital terrain mapping of the underside of sea ice to be done from an ice-launched autonomous underwater vehicle (AUV) was carried out at an ice camp in the Beaufort Sea using the Gavia vehicle, which could be launched and recovered through 3 × 1 m holes. Gavia was equipped with a GeoSwath 500 kHz interferometric sonar system, which yielded swaths of typical width 80 m. The imagery showed the morphological distinctions between first-year (FY) and multi-year (MY) ice undersides, the contrast between the shapes of FY and MY ridges, and the appearance of refrozen leads. Ice drafts were validated by drilling, and it was found that ridge slope statistics and local probability density functions (PDFs) of draft could be derived with high precision. The special opportunities offered by access to 3-D mapping are pointed out.

  14. Analysis of atmosphere-sea ice interactions in the Arctic basin using ESMR microwave data

    NASA Technical Reports Server (NTRS)

    Crane, R. G.; Barry, R. G.; Zwally, H. J.

    1982-01-01

    Data from the Electrically Scanning Microwave Radiometer (ESMR) on Nimbus-5 are used to determine the spatial and temporal patterns of change in microwave brightness signatures of Arctic sea ice during a full annual cycle (1973/74). Interactions of ice conditions with the atmosphere are examined using grid point data for surface air temperature and atmospheric pressure. Principal components analysis is used to examine the major elements present in the microwave and atmospheric data. Component scores from these analyses are then used in a canonical correlation analysis to determine interassociations present between the ice and atmosphere in the Beaufort Sea and the European sectors on a synoptic time scale. The synoptic weather conditions associated with the pattern of snow melt on the ice in spring 1974 are described, and a clarification of possible alternative interpretations of features identified as polynyi occurring at 80-85 deg N during the late summer 1974 is presented.

  15. How Vulnerable is Perennial Sea Ice? Insights from Earth's Late Cenozoic Natural Experiments (Invited)

    NASA Astrophysics Data System (ADS)

    Brigham-Grette, J.; Polyak, L. V.; Caissie, B.; Sharko, C. J.; Petsch, S.

    2010-12-01

    Sea ice is an important component of the climate system. Yet, reconstructions of Arctic sea ice conditions reflecting glacial and interglacial change over the past 3 million years are almost nonexistent. Our work to evaluate the sea ice and sea surface temperature record of the Bering Strait region builds on a review of the sea ice history of the pan-Arctic. The best estimates of sea ice make use of indirect proxies based on reconstructions of treeline, sea surface temperatures, depositional systems, and the ecological preferences of extant marine microfossil species. The development of new proxies of past sea ice extent including microfossil assemblages (diatoms, ostracodes) and biomarker proxies (IP25) show promise for quantifying seasonal concentrations of sea ice cover on centennial to millennial timescales. Using both marine and terrestrial information, periods of restricted sea ice and ice-free Arctic conditions can be inferred for parts of the late Cenozoic. The Arctic Ocean borderlands contain clear stratigraphic evidence for forested conditions at intervals over the past 50 million years, recording the migration of treeline from High Arctic coastal locations within the Canadian Archipelago. Metasequoia forests of the peak Eocene gave way to a variety of biomass-rich circumarctic redwood forests by 46 Ma. Between 23 and 16 Ma, cool-temperate metasequoia forests dominated NE Alaska and the Yukon while mixed conifer-hardwood forests (similar to those of modern southern maritime Canada and New England) dominated the central Canadian Archipelago. By 16 Ma, these forests gave way to larch and spruce. From 5 to 3 Ma the braid plains of the Beaufort Fm were dominated by over 100 vascular plants including pine and birch, while other locations remained dominated by spruce and larch. Boreal conditions across northern Greenland and arctic Alaska are consistent with the presence of bivalve Arctica islandica in marine sediments capping the Beaufort Formation on Meighen

  16. The delivery of organic contaminants to the Arctic food web: why sea ice matters.

    PubMed

    Pućko, Monika; Stern, Gary A; Macdonald, Robie W; Jantunen, Liisa M; Bidleman, Terry F; Wong, Fiona; Barber, David G; Rysgaard, Søren

    2015-02-15

    For decades sea ice has been perceived as a physical barrier for the loading of contaminants to the Arctic Ocean. We show that sea ice, in fact, facilitates the delivery of organic contaminants to the Arctic marine food web through processes that: 1) are independent of contaminant physical-chemical properties (e.g. 2-3-fold increase in exposure to brine-associated biota), and 2) depend on physical-chemical properties and, therefore, differentiate between contaminants (e.g. atmospheric loading of contaminants to melt ponds over the summer, and their subsequent leakage to the ocean). We estimate the concentrations of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in melt pond water in the Beaufort Sea, Canadian High Arctic, in 2008, at near-gas exchange equilibrium based on Henry's law constants (HLCs), air concentrations and exchange dynamics. CUPs currently present the highest risk of increased exposures through melt pond loading and drainage due to the high ratio of melt pond water to seawater concentration (Melt pond Enrichment Factor, MEF), which ranges from 2 for dacthal to 10 for endosulfan I. Melt pond contaminant enrichment can be perceived as a hypothetical 'pump' delivering contaminants from the atmosphere to the ocean under ice-covered conditions, with 2-10% of CUPs annually entering the Beaufort Sea via this input route compared to the standing stock in the Polar Mixed Layer of the ocean. The abovementioned processes are strongly favored in first-year ice compared to multi-year ice and, therefore, the dynamic balance between contaminant inventories and contaminant deposition to the surface ocean is being widely affected by the large-scale icescape transition taking place in the Arctic.

  17. Sea level budget in the Arctic during the satellite altimetry era

    NASA Astrophysics Data System (ADS)

    Carret, Alice; Cazenave, Anny; Meyssignac, Benoît; Prandi, Pierre; Ablain, Michael; Andersen, Ole; Blazquez, Alejandro

    2016-04-01

    Studying sea level variations in the Arctic region is challenging because of data scarcity. Here we present results of the sea level budget in the Arctic (up to 82°N) during the altimetry era. We first investigate closure of the sea level budget since 2002 using altimetry data from Envisat and Cryosat for estimating sea level, temperature and salinity data from the ORAP5 reanalysis and GRACE space gravimetry to estimate the steric and mass components. Two altimetry sea level data sets are considered (from DTU and CLS), based on Envisat waveforms retracking. Regional sea level trends seen in the altimetric map, in particular over the Beaufort Gyre and along the eastern coast of Greenland are of steric origin. However, in terms of regional average, the steric component contributes very little to the observed sea level trend, suggesting a dominant mass contribution in the Arctic region. This is confirmed by GRACE-based ocean mass time series that agree very well with the altimetry-based sea level time series. Direct estimate of the mass component is not possible prior to GRACE. Thus we estimated the mass contribution over the whole altimetry era from the difference between altimetry-based sea level and the ORAP5 steric component. Finally we compared altimetry-based coastal sea level with tide gauge records available along Norwegian, Greenland and Siberian coastlines and investigated whether the Arctic Oscillation that was the main driver of coastal sea level in the Arctic during the past decades still plays a dominant role or if other factors (e.g., of anthropogenic origin) become detectable.

  18. New High-Resolution Images of Summer Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Kwok, Ronald; Untersteiner, Norbert

    2011-02-01

    In 1995 a group of government and academic scientists were appointed by the vice president of the United States to review and advise on acquisitions of imagery obtained by classified intelligence satellites (National Technical Means) and to recommend the declassification of certain data sets for the benefit of science. The group is called MEDEA and was first described by Richelson [1998]. MEDEA disbanded in 2000 but reassembled in 2008. On 15 June 2009, under the auspices of MEDEA, the U.S. Geological Survey (USGS) released to the public as Literal Image Derived Products (LIDPs) numerous images with 1-meter resolution acquired since 1999 at six locations in the Arctic Basin (Beaufort Sea, Canadian Arctic, Fram Strait, East Siberian Sea, Chukchi Sea, and Point Barrow). These locations are named “fiducial sites” to suggest that the collected imagery establishes a baseline data set for understanding recent and future changes. Data in the Global Fiducials Library (GFL) can be accessed via http://gfl.usgs.gov/. This data repository is updated by USGS as additional data become available.

  19. Total and methylated mercury in Arctic multiyear sea ice.

    PubMed

    Beattie, Sarah A; Armstrong, Debbie; Chaulk, Amanda; Comte, Jérôme; Gosselin, Michel; Wang, Feiyue

    2014-05-20

    Mercury is one of the primary contaminants of concern in the Arctic marine ecosystem. While considerable efforts have been directed toward understanding mercury cycling in the Arctic, little is known about mercury dynamics within Arctic multiyear sea ice, which is being rapidly replaced with first-year ice. Here we report the first study on the distribution and potential methylation of mercury in Arctic multiyear sea ice. Based on three multiyear ice cores taken from the eastern Beaufort Sea and McClure Strait, total mercury concentrations ranged from 0.65 to 60.8 pM in bulk ice, with the highest values occurring in the topmost layer (∼40 cm) which is attributed to the dynamics of particulate matter. Methylated mercury concentrations ranged from below the method detection limit (<0.1 pM) to as high as 2.64 pM. The ratio of methylated to total mercury peaked, up to ∼40%, in the mid to bottom sections of the ice, suggesting the potential occurrence of in situ mercury methylation. The annual fluxes of total and methylated mercury into the Arctic Ocean via melt of multiyear ice are estimated to be 420 and 42 kg yr(-1), respectively, representing an important and changing source of mercury and methylmercury into the Arctic Ocean marine ecosystem.

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

    PubMed

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

    2011-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Reduced body size and cub recruitment in polar bears associated with sea ice decline.

    PubMed

    Rode, Karyn D; Amstrup, Steven C; Regehr, Eric V

    2010-04-01

    Rates of reproduction and survival are dependent upon adequate body size and condition of individuals. Declines in size and condition have provided early indicators of population decline in polar bears (Ursus maritimus) near the southern extreme of their range. We tested whether patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort Sea of Alaska were related to the availability of preferred sea ice habitats and whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. The mean skull size and body length of all polar bears over three years of age declined over time, corresponding with long-term declines in the spatial and temporal availability of sea ice habitat. Body size of young, growing bears declined over time and was smaller after years when sea ice availability was reduced. Reduced litter mass and numbers of yearlings per female following years with lower availability of optimal sea ice habitat, suggest reduced reproductive output and juvenile survival. These results, based on analysis of a long-term data set, suggest that declining sea ice is associated with nutritional limitations that reduced body size and reproduction in this population.

  3. Retrieval of Sea Ice Freeboard from ICESat-2 Multi-beam Altimetry

    NASA Astrophysics Data System (ADS)

    Kwok, R.; Hoffmann, J. F.; Markus, T.

    2015-12-01

    We illustrate our approach for retrieval of sea ice freeboard in height measurements from the multi-beam lidar on ICESat-2, using data acquired by a Multiple Altimeter Beam Experimental Lidar (MABEL). Prior to launch, MABEL serves as an airborne implementation for testing and algorithm development. Thus far, acquired data sets include flights over Arctic sea ice from the spring and summer: one in April 2012 (north of the Arctic coast of Greenland, and the other in the East Greenland Sea) and the other in July 2014 (Beaufort Sea). Here, we briefly describe the phenomenology of photon distributions in the sea ice returns and our approach for finding the heights of the ice and water surfaces, and the achievable height precision is discussed. Retrieved surface heights over relatively flat leads in the ice cover suggest that precisions of several centimeters are attainable. Comparisons of nearly coincident elevation profiles from MABEL with those acquired by an analog lidar show good agreement. Discrimination of ice and open water, a crucial step in the determination of sea ice freeboard and the estimation of ice thickness, is facilitated by contrasts in the observed signal/background photon statistics.

  4. Reduced body size and cub recruitment in polar bears associated with sea ice decline

    USGS Publications Warehouse

    Rode, K.D.; Amstrup, Steven C.; Regehr, E.V.

    2010-01-01

    Rates of reproduction and survival are dependent upon adequate body size and condition of individuals. Declines in size and condition have provided early indicators of population decline in polar bears (Ursus maritimus) near the southern extreme of their range. We tested whether patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort Sea of Alaska were related to the availability of preferred sea ice habitats and whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. The mean skull size and body length of all polar bears over three years of age declined over time, corresponding with long-term declines in the spatial and temporal availability of sea ice habitat. Body size of young, growing bears declined over time and was smaller after years when sea ice availability was reduced. Reduced litter mass and numbers of yearlings per female following years with lower availability of optimal sea ice habitat, suggest reduced reproductive output and juvenile survival. These results, based on analysis of a longterm data set, suggest that declining sea ice is associated with nutritional limitations that reduced body size and reproduction in this population. ?? 2010 by the Ecological Society of America.

  5. Transport of contaminants by Arctic sea ice and surface ocean currents

    SciTech Connect

    Pfirman, S.

    1995-12-31

    Sea ice and ocean currents transport contaminants in the Arctic from source areas on the shelves, to biologically active regions often more than a thousand kilometers away. Coastal regions along the Siberian margin are polluted by discharges of agricultural, industrial and military wastes in river runoff, from atmospheric deposition and ocean dumping. The Kara Sea is of particular concern because of deliberate dumping of radioactive waste, as well as the large input of polluted river water. Contaminants are incorporated in ice during suspension freezing on the shelves, and by atmospheric deposition during drift. Ice releases its contaminant load through brine drainage, surface runoff of snow and meltwater, and when the floe disintegrates. The marginal ice zone, a region of intense biological activity, may also be the site of major contaminant release. Potentially contaminated ice from the Kara Sea is likely to influence the marginal ice zones of the Barents and Greenland seas. From studies conducted to date it appears that sea ice from the Kara Sea does not typically enter the Beaufort Gyre, and thus is unlikely to affect the northern Canadian and Alaskan margins.

  6. Seasonal sea ice predictions for the Arctic based on assimilation of remotely sensed observations

    NASA Astrophysics Data System (ADS)

    Kauker, F.; Kaminski, T.; Ricker, R.; Toudal-Pedersen, L.; Dybkjaer, G.; Melsheimer, C.; Eastwood, S.; Sumata, H.; Karcher, M.; Gerdes, R.

    2015-10-01

    The recent thinning and shrinking of the Arctic sea ice cover has increased the interest in seasonal sea ice forecasts. Typical tools for such forecasts are numerical models of the coupled ocean sea ice system such as the North Atlantic/Arctic Ocean Sea Ice Model (NAOSIM). The model uses as input the initial state of the system and the atmospheric boundary condition over the forecasting period. This study investigates the potential of remotely sensed ice thickness observations in constraining the initial model state. For this purpose it employs a variational assimilation system around NAOSIM and the Alfred Wegener Institute's CryoSat-2 ice thickness product in conjunction with the University of Bremen's snow depth product and the OSI SAF ice concentration and sea surface temperature products. We investigate the skill of predictions of the summer ice conditions starting in March for three different years. Straightforward assimilation of the above combination of data streams results in slight improvements over some regions (especially in the Beaufort Sea) but degrades the over-all fit to independent observations. A considerable enhancement of forecast skill is demonstrated for a bias correction scheme for the CryoSat-2 ice thickness product that uses a spatially varying scaling factor.

  7. Caspian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this Moderate-resolution Imaging Spectroradiometer (MODIS) image from December 3, 2001, winter sea ice can be seen forming in the shallow waters of the northern Caspian (left) and Aral (upper right) Seas. Despite the inflow of the Volga River (upper left), the northern portion of the Caspian Sea averages only 17 feet in depth, and responds to the region's continental climate, which is cold in winter and hot and dry in the summer. The southern part of the Sea is deeper and remains ice-free throughout the winter. The dirty appearance of the ice may be due to sediment in the water, but may also be due to wind-driven dust. The wind in the region can blow at hurricane-force strength and can cause the ice to pile up in hummocks that are anchored to the sea bottom. The eastern portion of the Aral Sea is also beginning to freeze. At least two characteristics of the Aral Sea 'compete' in determining whether its waters will freeze. The Sea is shallow, which increases the likelihood of freezing, but it is also very salty, which means that lower temperatures are required to freeze it than would be required for fresh water. With average December temperatures of 18oF, it's clearly cold enough to allow ice to form. As the waters that feed the Aral Sea continue to be diverted for agriculture, the Sea becomes shallower and the regional climate becomes even more continental. This is because large bodies of water absorb and retain heat, moderating seasonal changes in temperature. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  8. Prevalence and antibiogram profiling of Escherichia coli pathotypes isolated from the Kat River and the Fort Beaufort abstraction water.

    PubMed

    Nontongana, Nolonwabo; Sibanda, Timothy; Ngwenya, Elvis; Okoh, Anthony I

    2014-08-12

    Escherichia coli is a widespread bacterium encompassing a variety of strains, ranging from highly pathogenic strains, causing worldwide outbreaks of severe diseases to avirulent, well characterized safe laboratory strains. This study evaluated the prevalence and antibiogram profiles of E. coli pathotypes isolated from the Kat River and Fort Beaufort abstraction water. A total of 171 out of 278 confirmed E. coli isolates were positive for at least one pathogenic determinant and these included enteropathogenic E. coli (6%), enterotoxigenic E. coli (47%), uropathogenic E. coli (2%), neonatal meningitis E. coli (5%), diffusely adherent E. coli (1%) and enterohaemorrhagic E. coli (1%). Interestingly, enteroinvasive and enteroaggregative E. coli were not detected. The phenotypic antibiogram profiles of the isolates revealed that all were resistant to penicillin G, while 98% and 38% of the pathotypes were resistant to ampicillin and trimethoprim-sulphamethoxazole, respectively. About 8% of the isolates were resistant to streptomycin. More than half of the isolates exhibited multiple antibiotic resistance with 44% being resistant to three antibiotics and 8% resistant to four antibiotics. We conclude that the Kat River is a reservoir of potentially virulent antibiotic resistant E. coli strains that can cause serious health risks to humans who drink raw water from this river, or in the case that consumption of treated drinking water coincides with failed drinking water processes.

  9. Prevalence and Antibiogram Profiling of Escherichia coli Pathotypes Isolated from the Kat River and the Fort Beaufort Abstraction Water

    PubMed Central

    Nontongana, Nolonwabo; Sibanda, Timothy; Ngwenya, Elvis; Okoh, Anthony I.

    2014-01-01

    Escherichia coli is a widespread bacterium encompassing a variety of strains, ranging from highly pathogenic strains, causing worldwide outbreaks of severe diseases to avirulent, well characterized safe laboratory strains. This study evaluated the prevalence and antibiogram profiles of E. coli pathotypes isolated from the Kat River and Fort Beaufort abstraction water. A total of 171 out of 278 confirmed E. coli isolates were positive for at least one pathogenic determinant and these included enteropathogenic E. coli (6%), enterotoxigenic E. coli (47%), uropathogenic E. coli (2%), neonatal meningitis E. coli (5%), diffusely adherent E. coli (1%) and enterohaemorrhagic E. coli (1%). Interestingly, enteroinvasive and enteroaggregative E. coli were not detected. The phenotypic antibiogram profiles of the isolates revealed that all were resistant to penicillin G, while 98% and 38% of the pathotypes were resistant to ampicillin and trimethoprim-sulphamethoxazole, respectively. About 8% of the isolates were resistant to streptomycin. More than half of the isolates exhibited multiple antibiotic resistance with 44% being resistant to three antibiotics and 8% resistant to four antibiotics. We conclude that the Kat River is a reservoir of potentially virulent antibiotic resistant E. coli strains that can cause serious health risks to humans who drink raw water from this river, or in the case that consumption of treated drinking water coincides with failed drinking water processes. PMID:25119699

  10. Dynamics of an idealized Beaufort Gyre: 1. The effect of a small beta and lack of western boundaries

    NASA Astrophysics Data System (ADS)

    Yang, Jiayan; Proshutinsky, Andrey; Lin, Xiaopei

    2016-02-01

    The Beaufort Gyre in the Arctic Ocean differs from a typical moderate-latitude gyre in some major aspects of its dynamics. First, it is located in a basin without a western boundary, which is essential for closing midlatitude circulations. Second, the gradient in Coriolis parameter, β, is small and so the validity of the Sverdrup balance is uncertain. In this paper, we use an idealized two-layer model to examine several processes that are related to these two issues. In a circular basin with closed geostrophic contours in interior, the variability of vorticity in the upper layer is dominated by eddies. But in the time-mean circulation, the main dynamical balance in the basin's interior is between the curl of wind stress and the eddy vorticity fluxes. The torque of friction becomes important along the boundary where the rim current is strong. It is found that the smallness of β has only a relatively small impact in a circular basin without a meridional boundary. The gyre is considerably more sensitive to the existence of a meridional boundary. The time-mean circulation weakens considerably when a peninsula is inserted between the model's center and the rim. (One side of the peninsula is dynamically equivalent to a midlatitude western boundary.) The gyre's sensitivity to β has also increased significantly when a meridional boundary is present. Subsurface ridges have similar effects on the gyre as a boundary, indicating that such topographic features may substitute, to some extents, the dynamical role of a western boundary.

  11. Evaluation of Structural Best Management Practices for Highway Runoff in Beaufort and Colleton Counties, South Carolina, 2005-2006

    USGS Publications Warehouse

    Conlon, Kevin; Journey, Celeste

    2009-01-01

    As part of the National Pollutant Discharge Elimination System (NPDES) permit program mandated in the Clean Water Act, the South Carolina Department of Transportation (SCDOT) is required to address the quality of stormwater runoff from state-maintained roadways. From 2005 to 2006, the SCDOT and the U.S. Geological Survey (USGS) worked cooperatively in Beaufort and Colleton Counties, South Carolina (SC), to evaluate the performance of four different structural devices that served as best management practices (BMPs). These structural devices were installed to lessen the potential effects of stormwater runoff on water quality in waterways near state roads. The purpose of this Fact Sheet is to summarize results published in the USGS Scientific Investigations Report 2008-5150. The report documents the ability of these four BMP devices to remove suspended sediment, metals, nutrients, and organics compounds in stormwater runoff. The quantity of rainfall and stormflow and quality of stormwater entering and leaving the BMPs were monitored during 12-13 storms over a 21-month period. The results provide the SCDOT with quantitative information to evaluate whether or not the BMPs effectively enhanced stormwater quality. This information can be used by the SCDOT and other State, local, and Federal agencies in the selection of appropriate BMPs for future installation.

  12. Arabian Sea

    Atmospheric Science Data Center

    2013-04-16

    ... sometimes results in copious phytoplankton production and oxygen depletion of the subsurface waters. Although red phytoplankton fluorescences have been associated with the low oxygen concentrations in the intermediate and deep waters of the Arabian Sea, ...

  13. Observation of melt onset on multiyear Arctic sea ice using the ERS 1 synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Winebrenner, D. P.; Nelson, E. D.; Colony, R.; West, R. D.

    1994-01-01

    We present nearly coincident observations of backscattering from the Earth Remote-Sensing Satellite (ERS) 1 synthetic aperture radar (SAR) and of near-surface temperature from six drifting buoys in the Beaufort Sea, showing that the onset of melting in snow on multiyear sea ice is clearly detectable in the SAR data. Melt onset is marked by a clean, steep decrease in the backscattering cross section of multiyear ice at 5.3 GHz and VV polarization. We investigate the scattering physics responsible for the signature change and find that the cross section decrease is due solely to the appearance of liquid water in the snow cover overlying the ice. A thin layer of moist snow is sufficient to cause the observed decrease. We present a prototype algorithm to estimate the date of melt onset using the ERS 1 SAR and apply the algorithm first to the SAR data for which we have corresponding buoy temperatures. The melt onset dates estimated by the SAR algorithm agree with those obtained independently from the temperature data to within 4 days or less, with the exception of one case in which temperatures oscillated about 0 C for several weeks. Lastly, we apply the algorithm to the entire ERS 1 SAR data record acquired by the Alaska SAR Facility for the Beaufort Sea north of 73 deg N during the spring of 1992, to produce a map of the dates of melt onset over an area roughly 1000 km on a side. The progression of melt onset is primarily poleward but shows a weak meridional dependence at latitudes of approximately 76 deg-77 deg N. Melting begins in the southern part of the study region on June 13 and by June 20 has progressed to the northermost part of the region.

  14. Sea Legs

    NASA Astrophysics Data System (ADS)

    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.

  15. Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season.

    PubMed

    Divoky, G J; Douglas, D C; Stenhouse, I J

    2016-09-01

    Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September-May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011-2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January-April. Most birds occupied the MIZ in regions averaging 30-60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d(-1), primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice.

  16. Spatial patterns of increases and decreases in the length of the sea ice season in the north polar region, 1979-1986

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    1992-01-01

    Recently it was reported that sea ice extents in the Northern Hemisphere showed a very slight but statistically significant decrease over the 8.8-year period of the Nimbus 7 scanning multichannel microwave radiometer (SMMR) data set. In this paper the same SMMR data are used to reveal spatial patterns in increasing and decreasing sea ice coverage. Specifically, the length of the ice season is mapped for each full year of the SMMR data set (1979-1986), and the trends over the 8 years in these ice season lengths are also mapped. These trends show considerable spatial coherence, with a shortening in the sea ice season apparent in much of the eastern hemisphere of the north polar ice cover, particularly in the Sea of Okhotsk, the Barents Sea, and the Kara Sea, and a lengthening of the sea ice season apparent in much of the western hemisphere of the north polar ice cover, particularly in Davis Strait, the Labrador Sea, and the Beaufort Sea.

  17. Arctic Sea Ice Thickness - Past, Present And Future

    NASA Astrophysics Data System (ADS)

    Wadhams, P.

    2007-12-01

    In November 2005 the International Workshop on Arctic Sea Ice Thickness: Past, Present and Future was held at Rungstedgaard Conference Center, near Copenhagen, Denmark. The proceedings of the Workshop were subsequently published as a book by the European Commission. In this review we summarise the conclusions of the Workshop on the techniques which show the greatest promise for thickness monitoring on different spatial and temporal scales, and for different purposes. Sonic methods, EM techniques, buoys and satellite methods will be considered. Some copies of the book will be available at the lecture, and others can be ordered from the European Commission. The paper goes on to consider early results from some of the latest measurements on Arctic sea ice thickness done in 2007. These comprise a trans-Arctic voyage by a UK submarine, HMS "Tireless", equipped with a Kongsberg 3002 multibeam sonar which generates a 3-D digital terrain map of the ice underside; and experiments at the APLIS ice station in the Beaufort Sea carried out by the Gavia AUV equipped with a GeoSwath interferometric sonar. In both cases 3-D mapping of sea ice constitutes a new step forward in sea ice data collection, but in the case of the submarine the purpose is to map change in ice thickness (comparing results with a 2004 "Tireless" cruise and with US and UK data prior to 2000), while for the small AUV the purpose is intensive local mapping of a few ridges to improve our knowledge of their structure, as part of a multisensor programme

  18. Variations in the Arctic's multiyear sea ice cover: A neural network analysis of SMMR-SSM/I data, 1979-2004

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Eremeev, V.A.; Platonov, N.G.

    2005-01-01

    A 26-year (1979-2004) observational record of January multiyear sea ice distributions, derived from neural network analysis of SMMR-SSM/I passive microwave satellite data, reveals dense and persistent cover in the central Arctic basin surrounded by expansive regions of highly fluctuating interannual cover. Following a decade of quasi equilibrium, precipitous declines in multiyear ice area commenced in 1989 when the Arctic Oscillation shifted to a pronounced positive phase. Although extensive survival of first-year ice during autumn 1996 fully replenished the area of multiyear ice, a subsequent and accelerated decline returned the depletion to record lows. The most dramatic multiyear sea ice declines occurred in the East Siberian, Chukchi, and Beaufort Seas.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  20. A comparison of the South China Sea and Canada Basin: two small marginal ocean basins with hyper-extended margins and central zones of sea-floor spreading.

    NASA Astrophysics Data System (ADS)

    Li, L.

    2015-12-01

    Both the South China Sea and Canada Basin preserve oceanic spreading centres and adjacent passive continental margins characterized by broad COT zones with hyper-extended continental crust. We have investigated the nature of strain accommodation in the regions immediately adjacent to the oceanic spreading centres in these two basins using 2-D backstripping subsidence reconstructions, coupled with forward modelling constrained by estimates of upper crustal extensional faulting. Modelling is better constrained in the South China Sea but our results for the Beaufort Sea are analogous. Depth-dependent extension is required to explain the great depth of both basins because only modest upper crustal faulting is observed. A weak lower crust in the presence of high heat flow is suggested for both basins. Extension in the COT may continue even after sea-floor spreading has ceased. The analogous results for the two basins considered are discussed in terms of (1) constraining the timing and distribution of crustal thinning along the respective continental margins, (2) defining the processes leading to hyper-extension of continental crust in the respective tectonic settings and (3) illuminating the processes that control hyper-extension in these basins and more generally.

  1. Sea Ice

    NASA Technical Reports Server (NTRS)

    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.

  2. Aral Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This series of MODIS images shows the dwindling Aral Sea. Once one of the world's largest freshwater lakes, the Aral Sea has decreased by as much as 60% over the past few decades due to diversion of the water to grow cotton and rice. These diversion have dropped the lake levels, increased salinity, and nearly decimated the fishing industry. The previous extent of the lake is clearly visible as a whitish perimeter in these image from April 16, May 18, and June 3, 2002. s. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  3. Black Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Black Sea in eastern Russia is experiencing an ongoing phytoplankton bloom. This image, the most recent in a series that began in early may, shows the waters to be even more colorful than before. part of the increased brightness may be due to the presence of sun glint , especially in the center of the sea. However, more organisms appear to be present as well, their photosynthetic pigments reflecting different wavelengths of light.This Moderate Resolution Imaging Spectroradiometer (MODIS) image was captured on June 15, 2002.

  4. Siku: A Sea Ice Discrete Element Method Model on a Spherical Earth

    NASA Astrophysics Data System (ADS)

    Kulchitsky, A. V.; Hutchings, J. K.; Johnson, J.

    2014-12-01

    Offshore oil and gas exploration and production activities in the Beaufort and Chukchi Seas can be significantly and adversely affected by sea ice. In the event of an oil spill, sea ice complicates the tracking of ice/oil trajectories and can hinder cleanup operations. There is a need for a sea ice dynamics model that can accurately simulate ice pack deformation and failure to improve the ability to track ice/oil trajectories and support oil response operations. A discrete element method (DEM) model, where each ice floe is represented by discrete elements that are initially bonded (frozen) together will be used to address the difficulty continuum modeling approaches have with representing discrete phenomena in sea ice, such as the formation of leads and ridges. Each discrete element in the DEM is a rigid body driven by environmental forcing (wind, current and Coriolis forces) and interaction forces with other discrete elements (compression, shear, tension, bond rupture and regrowth). We introduce a new DEM model ``Siku'', currently under development, to simulate ice drift of an ice floe on a spherical Earth. We will present initial free-drift results. Siku is focused on improving sea ice interaction mechanics and providing an accurate geometrical representation needed for basin scale and regional simulations. Upon completion, Siku will be an open source GNU GPL licensed user friendly program with embedded python capability for setting up simulations "scenarios" and coupling with other models to provide forcing fields. We use a unique quaternion representation for position and orientation of polygon sea-ice elements that use a second order integration scheme of sea-ice element motion on the Earth's sphere that does not depend on the location of the element and, hence, avoids numerical problems near the pole.

  5. Sea Clutter

    DTIC Science & Technology

    1990-09-28

    OE-10, 47i- 476, (1985). 15. S. Tang and 0. H. Shemdin , "Measurement of High-frequency Waves using a Wave Fol- lower," J. Geophys. Res. 88. 9832...DESCRIPTION OF THE SEA SURFACE ................................................................... 2 The Wave Spectrum...Very Low Grazing Angles ......................................................................... 16 At HF and mm- Wave Frequencies

  6. Marine Corps Child Care: User Fee Increases at Parris Island and Beaufort Installations. Report to the Chairman, Subcommittee on Military Personnel and Compensation, Committee on Armed Services, House of Representatives.

    ERIC Educational Resources Information Center

    General Accounting Office, Washington, DC. Div. of Human Resources.

    This report describes ways in which appropriated and nonappropriated funds were used to support morale, welfare, and recreation (MWR) activities, which include child care, at the Marine Corps Recruit Depot, Parris Island, South Carolina, and the Marine Corps Air Station, Beaufort, South Carolina. In addition, the report provides information on…

  7. Hypsometry and volume of the Arctic Ocean and its constituent seas

    NASA Astrophysics Data System (ADS)

    Jakobsson, Martin

    2002-05-01

    This paper presents an analysis of the Arctic Ocean and its constituent seas for seafloor area distribution versus depth and ocean volume. The bathymetry from the International Bathymetric Chart of the Arctic Ocean (IBCAO) is used together with limits defining this ocean and its constituent seas from the International Hydrographic Organization (IHO) as well as redefined limits constructed to confine the seas to the shallow shelves. IBCAO is a bathymetric grid model with a resolution of 2.5 × 2.5 km, which significantly improved the portrayal of the Arctic Ocean seafloor through incorporation of newly released bathymetric data including echo soundings from U.S. and British navies, scientific nuclear submarine cruises, and icebreaker cruises. This analysis of seafloor area and ocean volume is the first for the Arctic Ocean based on this new and improved portrayal of the seafloor as represented by IBCAO. The seafloor area and volume are calculated for different depths starting from the present sea level and progressing in increments of 10 m to a depth of 500 m and in increments of 50 m from 550 m down to the deepest depth within each of the analyzed seas. Hypsometric curves expressed as simple histograms of the frequencies in different depth bins and depth plotted against cumulative area for each of the analyzed seas are presented. The area and volume calculations show that the entire IHO-defined Arctic Ocean makes up ~4.3% of the total ocean area but only ~1.4% of the volume. Furthermore, the IHO Arctic Ocean is the shallowest (mean depth 1201 m) of all the major oceans and their adjacent seas. The continental shelf area, from the coasts out to the shelf break, make up as much as ~52.9% of the total area in the Arctic Ocean, defined in this work as consisting of the oceanic deep Arctic Ocean Basin; the broad continental shelves of the Barents, Kara, Laptev, East Siberian, Chukchi, and Beaufort Seas; the White Sea; and the narrow continental shelf off both the

  8. Do common eiders nest in kin groups? Microgeographic genetic structure in a philopatric sea duck

    USGS Publications Warehouse

    Sonsthagen, S.A.; Talbot, S.L.; Lanctot, Richard B.; McCracken, K.G.

    2010-01-01

    We investigated local genetic associations among female Pacific common eiders (Somateria mollissima v-nigrum) nesting in a stochastic Arctic environment within two groups of barrier islands (Simpson Lagoon and Mikkelsen Bay) in the Beaufort Sea, Alaska. Nonrandom genetic associations were observed among nesting females using regional spatial autocorrelation analyses for distance classes up to 1000 m in Simpson Lagoon. Nearest-neighbour analyses identified clusters of genetically related females with positive lr values observed for 0-13% and 0-7% of the comparisons in Simpson Lagoon and Mikkelsen Bay, respectively, across years. These results indicate that a proportion of females are nesting in close proximity to more genetically related individuals, albeit at low frequency. Such kin groupings may form through active association between relatives or through natal philopatry and breeding site fidelity. Eiders nest in close association with driftwood, which is redistributed annually by seasonal storms. Yet, genetic associations were still observed. Microgeographic structure may thus be more attributable to kin association than natal philopatry and site fidelity. However, habitat availability may also influence the level of structure observed. Regional structure was present only within Simpson Lagoon and this island group includes at least three islands with sufficient driftwood for colonies, whereas only one island at Mikkelsen Bay has these features. A long-term demographic study is needed to understand more fully the mechanisms that lead to fine-scale genetic structure observed in common eiders breeding in the Beaufort Sea. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

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

    PubMed

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

    2015-05-20

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

  10. Arctic Ocean microbial community structure before and after the 2007 record sea ice minimum.

    PubMed

    Comeau, André M; Li, William K W; Tremblay, Jean-Éric; Carmack, Eddy C; Lovejoy, Connie

    2011-01-01

    Increasing global temperatures are having a profound impact in the Arctic, including the dramatic loss of multiyear sea ice in 2007 that has continued to the present. The majority of life in the Arctic is microbial and the consequences of climate-mediated changes on microbial marine food webs, which are responsible for biogeochemical cycling and support higher trophic levels, are unknown. We examined microbial communities over time by using high-throughput sequencing of microbial DNA collected between 2003 and 2010 from the subsurface chlorophyll maximum (SCM) layer of the Beaufort Sea (Canadian Arctic). We found that overall this layer has freshened and concentrations of nitrate, the limiting nutrient for photosynthetic production in Arctic seas, have decreased. We compared microbial communities from before and after the record September 2007 sea ice minimum and detected significant differences in communities from all three domains of life. In particular, there were significant changes in species composition of Eukarya, with ciliates becoming more common and heterotrophic marine stramenopiles (MASTs) accounting for a smaller proportion of sequences retrieved after 2007. Within the Archaea, Marine Group I Thaumarchaeota, which earlier represented up to 60% of the Archaea sequences in this layer, have declined to <10%. Bacterial communities overall were less diverse after 2007, with a significant decrease of the Bacteroidetes. These significant shifts suggest that the microbial food webs are sensitive to physical oceanographic changes such as those occurring in the Canadian Arctic over the past decade.

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

    PubMed Central

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

    2015-01-01

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79°N). Here we present the first central Arctic Ocean (79–90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81–85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150–200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production. PMID:25993348

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  13. Is Ice-Rafted Sediment in a North Pole Marine Record Evidence for Perennial Sea-ice Cover?

    NASA Technical Reports Server (NTRS)

    Tremblay, L.B.; Schmidt, G.A.; Pfirman, S.; Newton, R.; DeRepentigny, P.

    2015-01-01

    Ice-rafted sediments of Eurasian and North American origin are found consistently in the upper part (13 Ma BP to present) of the Arctic Coring Expedition (ACEX) ocean core from the Lomonosov Ridge, near the North Pole (approximately 88 degrees N). Based on modern sea-ice drift trajectories and speeds, this has been taken as evidence of the presence of a perennial sea-ice cover in the Arctic Ocean from the middle Miocene onwards. However, other high latitude land and marine records indicate a long-term trend towards cooling broken by periods of extensive warming suggestive of a seasonally ice-free Arctic between the Miocene and the present. We use a coupled sea-ice slab-ocean model including sediment transport tracers to map the spatial distribution of ice-rafted deposits in the Arctic Ocean. We use 6 hourly wind forcing and surface heat fluxes for two different climates: one with a perennial sea-ice cover similar to that of the present day and one with seasonally ice-free conditions, similar to that simulated in future projections. Model results confirm that in the present-day climate, sea ice takes more than 1 year to transport sediment from all its peripheral seas to the North Pole. However, in a warmer climate, sea-ice speeds are significantly faster (for the same wind forcing) and can deposit sediments of Laptev, East Siberian and perhaps also Beaufort Sea origin at the North Pole. This is primarily because of the fact that sea-ice interactions are much weaker with a thinner ice cover and there is less resistance to drift. We conclude that the presence of ice-rafted sediment of Eurasian and North American origin at the North Pole does not imply a perennial sea-ice cover in the Arctic Ocean, reconciling the ACEX ocean core data with other land and marine records.

  14. Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

    NASA Astrophysics Data System (ADS)

    Gradinger, Rolf; Bluhm, Bodil; Iken, Katrin

    2010-01-01

    The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate ( N=24-65 per station) 0.25 m 2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l -1 (median 0.8 ind l -1). In level ice, low ice algal pigment concentrations (<0.1-15.8 μg Chl a l -1), low brine salinities (1.8-21.7) and flushing from the melting sea ice likely explain the low ice meiofauna concentrations. Higher abundances of Turbellaria, Nematoda and Harpacticoida also were observed in pressure ridges (0-200 ind l -1, median 40 ind l -1), although values were highly variable and only medians of Turbellaria were significantly higher in ridge ice than in level ice. Median abundances of under-ice amphipods at all ice types (level ice, various ice ridge structures) ranged from 8 to 114 ind m -2 per station and mainly consisted of Apherusa glacialis (87%), Onisimus spp. (7%) and Gammarus wilkitzkii (6%). Highest amphipod abundances were observed in pressure ridges at depths >3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high

  15. From Sea to Shining Sea

    ERIC Educational Resources Information Center

    Scott, Beverly

    2005-01-01

    Deep down in the depths of the sea, beautiful fish, mysterious ocean life, and unusual plants glimmer and glow in the eerie atmosphere of an ever-changing ocean. This article describes how, with this vision and a purpose in mind, three teachers pulled open classroom walls and joined forces so their second graders could create a mammoth 30 x 75"…

  16. Cross-stratified Wood: Enigmatic Woody Debris Deposits in Warm-Polar Fluvial Sediments (Pliocene Beaufort Formation, Nunavut)

    NASA Astrophysics Data System (ADS)

    Davies, N. S.; Gosse, J. C.; Rybczynski, N.

    2012-04-01

    Woody debris has been an important sediment component and a significant geomorphic agent in pristine fluvial systems since the Devonian. In recent years a large volume of research has focussed on various aspects of the importance of woody debris within the fluvial realm; from the evolutionary significance of fossil wood accumulations in the rock record to studies of the biogeomorphological and ecological importance of woody debris in modern rivers. In this presentation we describe cross-stratified woody debris deposits comprising organic detritus from a boreal-type treeline forest that included species of pine, birch, poplar, alder, spruce, eastern cedar, and larch, in both shrub and tree form. The cross-stratified wood is an enigmatic subset of fine woody debris which, to our knowledge, has never before been described from either the global stratigraphic record or modern fluvial environments. The deposits we describe are located within the Pliocene Beaufort Formation on Meighen Island, Nunavut, Canada, at a latitude of 80°N, and are compared with other cross-stratified woody debris deposits that have been noted elsewhere in the Pliocene of the Canadian Arctic. We make the robust observation that these deposits appear to be geographically and stratigraphically restricted to polar latitudes from a period of warm climatic conditions during the Pliocene (15-20 °C warmer mean annual temperature than the present day). In this regard it is possible to speculate that the transport of large amounts of woody debris as bedload is potentially a unique feature of forested high latitude rivers. Such bedload deposition requires a large amount of woody debris with a greater density than the fluid transporting it. The softwood composition of the debris suggests that this was most likely attained by saturation and subsequent entrainment of extensive accumulations of deadwood, promoted by unusually high rates of tree mortality and low rates of bacterial decomposition arising from

  17. A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Dupont, F.; Higginson, S.; Bourdallé-Badie, R.; Lu, Y.; Roy, F.; Smith, G. C.; Lemieux, J.-F.; Garric, G.; Davidson, F.

    2015-01-01

    As part of the CONCEPTS (Canadian Operational Network of Coupled Environmental PredicTion Systems) initiative, The Government of Canada is developing a high resolution (1/12°) ice-ocean regional model covering the North Atlantic and the Arctic oceans. The objective is to provide Canada with short-term ice-ocean predictions and hazard warnings in ice infested regions. To evaluate the modelling component (as opposed to the analysis - or data-assimilation - component), a series of hindcasts for the period 2003-2009 is carried out, forced at the surface by the Canadian Global Re-Forecasts. These hindcasts test how the model represent upper ocean characteristics and ice cover. Each hindcast implements a new aspect of the modelling or the ice-ocean coupling. Notably, the coupling to the multi-category ice model CICE is tested. The hindcast solutions are then assessed using a validation package under development, including in-situ and satellite ice and ocean observations. The conclusions are: (1) the model reproduces reasonably well the time mean, variance and skewness of sea surface height. (2) The model biases in temperature and salinity show that while the mean properties follow expectations, the Pacific Water signature in the Beaufort Sea is weaker than observed. (3) However, the modelled freshwater content of the Arctic agrees well with observational estimates. (4) The distribution and volume of the sea ice is shown to be improved in the latest hindcast thanks to modifications to the drag coefficients and to some degree as well to the ice thickness distribution available in CICE. (5) On the other hand, the model overestimates the ice drift and ice thickness in the Beaufort Gyre.

  18. Alkane, terpene and polycyclic aromatic hydrocarbon geochemistry of the Mackenzie River and Mackenzie shelf: Riverine contributions to Beaufort Sea coastal sediment

    NASA Astrophysics Data System (ADS)

    Yunker, Mark B.; Macdonald, Robie W.; Cretney, Walter J.; Fowler, Brian R.; McLaughlin, Fiona A.

    1993-07-01

    To study the largest source of river sediment to the Arctic Ocean, we have collected suspended particulates from the Mackenzie River in all seasons and sediments from the Mackenzie shelf between the river mouth and the shelf edge. These samples have been analyzed for alkanes, triterpenes and polycyclic aromatic hydrocarbons (PAHs). We found that naturally occurring hydrocarbons predominate in the river and on the shelf. These hydrocarbons include biogenic alkanes and triterpenes with a higher plant/peat origin, diagenetic PAHs from peat and plant detritus, petrogenic alkanes, triterpenes and PAHs from oil seeps and/or bitumens and combustion PAHs that are likely relict in peat deposits. Because these components vary independently, the season is found to strongly influence the concentration and composition of hydrocarbons in the Mackenzie River. While essentially the same pattern of alkanes, diagenetic hopanes and alkyl PAHs is observed in all river and most shelf sediment samples, alkane and triterpene concentration variations are strongly linked to the relative amount of higher plant/peat material. Polycyclic aromatic hydrocarbon molecular-mass profiles also appear to be tied primarily to varying proportions of peat, with an additional petrogenic component which is most likely associated with lithic material mobilized by the Mackenzie River at freshet. Consistent with the general lack of alkyl PAHs in peat, the higher PAHs found in the river are probably derived from forest and tundra fires. A few anthropogenic/pyrogenic compounds are manifest only at the shelf edge, probably due to a weakening of the river influence. We take this observation of pyrogenic PAHs and the pronounced source differences between two sediment samples collected at the shelf edge as evidence of a transition from dominance by the Mackenzie River to the geochemistry prevalent in Arctic regions far removed from major rivers.

  19. Shore Ice Ride-Up and Pile-Up Features. Part 2. Alaska’s Beaufort Sea Coast--1983 and 1984,

    DTIC Science & Technology

    1984-09-01

    up to 3 m high on one edge of On the northwest side of Narwhal Island (Fig. the sandbag perimeter wall and in places had cas- A2) the sandy gravel...ice southwest end of Narwhal Island, VA-m-thick ice ride-up on the south side of Pole Island (position was thrust from the west approximately 30 m 0...ups were seen on several of the Narwhal Island. In addition, in several places ice barrier islands located northeast of Anderson Pt. 14 % . -_ Figure

  20. Biogeographic provinces of total and methyl mercury in zooplankton and fish from the Beaufort and Chukchi seas: results from the SHEBA drift.

    PubMed

    Stern, G A; MacDonald, R W

    2005-07-01

    Samples of copepods (Calanus hyperboreus) and arctic cod (Boreogadus saida) were collected along the SHEBA (Surface HEat Budget of the Arctic) drift track, which commenced in the Canada Basin (October 1997) and finished in the Mendeleev Basin (October 1998). Here, we report total mercury (HgT) and CH3Hg concentrations in these biological samples and examine concentration variability along the drift track in the context of trophic variation, inputs from land, spring mercury depletion events (MDEs), and oceanographic provinces. We find background concentrations of HgT in C. hyperboreus as low as 0.02 microg/g (dw), with the Canada Basin samples exhibiting approximately 2-fold higher mercury concentrations than those from the Chukchi Plateau and Mendeleev Abyssal Plain. This east-to-west trend in mercury concentration is punctuated by two and possibly three intervals of elevated mercury (HgT, 0.10-0.12 microg/g (dw); CH3Hg, 0.023-0.028 microg/g (dw)) along the drift track. One interval of elevated HgT and CH3-Hg levels occurred during and shortly after melt. %CH3Hg reached a maximum of 60% during this time period, three times higher than any other time during the drift. This transient rise in C. hyperboreus CH3Hg concentration seems to strongly point to mercury accumulated in snow during MDEs. However, the alignment of elevated mercury samples with oceanographic fronts and the observed regional differences between basins suggest that variation of mercury concentration is primarily a consequence of ocean structure. Given that large animals such as whales selectively forage in regions of higher food concentration such as fronts, recent change in the ice climate of the western Arctic Ocean, perhaps mediated by changes in heat storage, may provide the means to change their exposure to mercury thus explaining observed increases in mercury concentrations in western beluga whales during the 1990s.

  1. Aerial Surveys of Endangered Whales in the Northern Bering, Eastern Chukchi and Alaskan Beaufort Seas, 1983: with a Five Year Review, 1979-1983.

    DTIC Science & Technology

    1984-06-01

    were1I seen. Three were seen between St. Lawrence Island and Cape Prince of Wales in late April. The spring migratory route near and east of Point Barrow...of Wales where large numbers of bowheads had been seen during the spring(s) of 1980 and 1981 (Ljungblad 1981, Ljungblad, et al., (a)1982). Few whales...Point Hope680." 670 tbue , 66 s Cpe Prince of Wales 650 Bering Son Nome ’f"_Z’ 640 . Figure 4. Distribution of 92 sightings representing 223 bowheads

  2. Aerial Surveys of Endangered Whales in the Northern Bering, Eastern Chukchi, and Alaskan Beaufort Seas, 1984: with a Six Year Review, 1979-1984.

    DTIC Science & Technology

    1985-06-01

    Scheidt supplied satellite imagery from the National Weather Service , U. S. Department of Commerce. Jeanne Cole and Barbara McAvoy of SEACO, Inc. typed...Swartz of SEACO, L Inc., Forrest Wood of the NOSC, Byron Morris of the National Marine Fisheries Service (NMFS), Douglas Chapman of the Marine Mammal...Minerals Management Service NMFS National Marine Fisheries Service , NOAA National Oceanographic and Atmospheric Administration * NOSC Naval Ocean

  3. Physical forcings and intense shelf-slope fluxes of particulate matter in the halocline waters of the Canadian Beaufort Sea during winter

    NASA Astrophysics Data System (ADS)

    Forest, Alexandre; Osborne, Philip D.; Fortier, Louis; Sampei, Makoto; Lowings, Malcolm G.

    2015-06-01

    Resolving the mechanisms that support the transfer of particulate matter across the shelf-slope interface is a key issue for the sustainable development of marine resources along continental margins. A better comprehension of shelf-slope exchanges is particularly needed in the Arctic Ocean given the intensification of human activities and rapid environmental changes in this region. Here, we use three years of physical and biogeochemical data collected with tautline moorings deployed from September 2009 to August 2012 over the slope of the Mackenzie Shelf to identify the processes that drive the lateral transport of particulate matter off the shelf. The main dataset consists of particle flux time-series collected with automated sediments traps deployed on moorings at ~80 and ~180 m depth over the mid-slope. We detected a strong vertical discrepancy in the magnitude of particulate mass fluxes that were 20-600% higher at ~180 m than at ~80 m, and up to ~1500% greater during the winter season alone. The high fluxes at ~180 m depth were linked to several sedimentation events occurring from November to May each year, which were not captured by the upper ~80 m traps. These differences corroborate previous studies that documented active transport of resuspended material near the bottom across the shelf-break and in the mid-water column over the slope. Consideration of particle fluxes along with synchronous current time-series, water column properties and meteorological data revealed that thermohaline convection and storm winds act as the main mechanisms underlying resuspension and transport processes. Their combination drives mesoscale eddy formation, downwelling flows and current surges that are characterized by moderate to high velocities (~20-80 cm s-1) sufficient to mobilize sediments. Turbidity near the shelf-break and particle fluxes over the slope were particularly enhanced in winter 2011 (mass fluxes up to ~2 g m-2 d-1) when a persistent downwelling-favorable wind regime and a large production of winter water were observed. Overall, the amount of winter water events correlated significantly (R2=0.76) with the magnitude of mass fluxes collected at ~180 m. Our analysis revealed a complex pattern of mean currents over the slope facilitating instabilities, frontal structures, shear and eddying motion. Additional work is needed on erosion mechanisms in the bottom boundary layer and their relationship to regional and mesoscale circulation and eddy activity over the upper slope.

  4. Blood-based biomarkers of selenium and thyroid status indicate possible adverse biological effects of mercury and polychlorinated biphenyls in Southern Beaufort Sea polar bears.

    PubMed

    Knott, Katrina K; Schenk, Patricia; Beyerlein, Susan; Boyd, Daryle; Ylitalo, Gina M; O'Hara, Todd M

    2011-11-01

    We examined biomarkers of selenium status (whole blood Se; serum Se; glutathione peroxidase activity) and thyroid status (concentrations and ratios of thyroxine, T4; tri-iodothyronine, T3; albumin) in polar bears to assess variations among cohorts, and relationships to circulating concentrations of contaminants. Concentrations of total mercury (Hg) in whole blood were similar among cohorts (prime aged males and females, older animals, ages≥16 years, and young animals, ages 1-5 years; 48.44±35. 81; p=0.253). Concentrations of sum of seven polychlorinated biphenyls (∑PCB7) in whole blood were greater in females (with and without cubs, 26.44±25.82 ng/g ww) and young (26.81±10.67 ng/g ww) compared to males (8.88±5.76 ng/g ww, p<0.001), and significantly related to reduced body condition scores (p<0.001). Concentrations of Se and albumin were significantly greater in males than females (whole blood Se, males, 42.34 pmol/g ww, females, 36.25±6.27 pmol/g ww, p=0.019; albumin, males, 4.34±0.34 g/dl, females, 4.10±0.29 g/dL, p=0.018). Glutathione peroxidase activity ranged from 109.1 to 207.8 mU/mg hemoglobin, but did not differ significantly by sex or age (p>0.08). Thyroid hormones were greater in females (solitary females and females with cubs) compared to males (p<0.001). Biomarkers of Se status and concentrations of T3 were significantly positively related to Hg in all prime aged polar bears (p<0.03). Albumin concentrations were significantly positively related to total TT4, and significantly negatively related to concentrations of ∑PCB7 (p<0.003). Total thyroxine (TT4) was significantly negatively associated with blood concentrations of ∑PCB7 in solitary females (p=0.045). These data suggest that female polar bears were more susceptible to changes in blood-based biomarkers of selenium and thyroid status than males. Further classifications of the physiologic states of polar bears and repeated measures of individuals over time are needed to accurately assess the biological impact of combined toxicant exposures.

  5. Historical changes in trace metals and hydrocarbons in nearshore sediments, Alaskan Beaufort Sea, prior and subsequent to petroleum-related industrial development: Part I. Trace metals.

    PubMed

    Naidu, A Sathy; Blanchard, Arny L; Misra, Debasmita; Trefry, John H; Dasher, Douglas H; Kelley, John J; Venkatesan, M Indira

    2012-10-01

    Concentrations of Fe, As, Ba, Cd, Cu, Cr, Pb, Mn, Ni, Sn, V and Zn in mud (<63μm size), and total and methyl Hg in gross sediment are reported for Arctic Alaska nearshore. Multivariate-PCA analysis discriminated seven station clusters defined by differences in metal concentrations, attributed to regional variations in granulometry and, as in Elson Lagoon, to focused atmospheric fluxes of contaminants from Eurasia. In Colville Delta-Prudhoe Bay, V increase was noted in 1985 and 1997 compared to 1977, and Ba increase from 1985 to 1997. Presumably the source of increased V is the local gas flaring plant, and the elevated Ba is due to barite accumulation from oil drilling effluents. In Prudhoe Bay, concentration spikes of metals in ∼1988 presumably reflect enhanced metals deposition following maximum oil drilling in 1980s. In summary, the Alaskan Arctic nearshore has remained generally free of metal contamination despite petroleum-related activities in past 40 years.

  6. Feasibility of dynamic models of the interaction of potential oil spills with bowhead and gray whales in the Bering, Chukchi, and Beaufort Seas

    SciTech Connect

    Reed, M.; Bowles, A.E.; Anderson, E.L.; Leatherwood, S.; Spaulding, M.L.

    1984-08-01

    Feasibility and design considerations for developing computer models of migratory bow-head and gray whales and linking such models to oil spill models for application in Alaskan Outer Continental Shelf areas were evaluated. A summary of all relevant bowhead and gray whale distributional and migration data were summarized and presented at monthly intervals. The data were, for the most part, deemed sufficient to prepare whale migration simulation models. A variety of whale migration conceptual models were devised and ranking was achieved by means of a scaling-weighted protocol. Existing oil spill trajectory and fate models, as well as conceptual models, were similarly ranked.

  7. Report on studies to monitor the interactions between offshore geophysical exploration activities and bowhead whales in the Alaskan Beaufort Sea, Fall 1982

    SciTech Connect

    Reeves, R.; Ljungblad, D.; Clarke, J.T.

    1983-07-01

    A total of 34 survey flights were initiated between 27 August and 4 October 1982 to assess the potential effects of marine geophysical survey work on westward migrating bowhead whales (Balaena mysticetus). No overt changes in whale behavior were observed that could unequivocally be interpreted as responses to seismic noise, with the possible exception of huddling behavior observed on 14-15 September that may have been caused by the onset of seismic sounds. Statistical analyses were performed on four categories of respiratory behavior (blows per surfacing, mean blow interval per surfacing, surface times and dive times) to test for differences between times when whales were and were not exposed to seismic sounds.

  8. Blood-based biomarkers of selenium and thyroid status indicate possible adverse biological effects of mercury and polychlorinated biphenyls in Southern Beaufort Sea polar bears

    PubMed Central

    Knott, Katrina K.; Schenk, Patricia; Beyerlein, Susan; Boyd, Daryle; Ylitalo, Gina M.; O’Hara, Todd. M.

    2011-01-01

    We examined biomarkers of selenium status (whole blood Se, serum Se, and glutathione peroxidase activity) and thyroid status (concentrations and ratios of thyroxine, T4, and tri-iodothyronine, T3, and albumin) in polar bears to assess variations among cohorts, and relationships to circulating concentrations of contaminants. Concentrations of total mercury (Hg) in whole blood were similar among cohorts (prime aged males and females, older animals ages ≥ 16 years, and young animals ages 1 – 5 years; 48.44 ± 35. 81; p = 0.253). Concentrations of sum of seven polychlorinated biphenyls (ΣPCB7) in whole blood were greater in females (with and without cubs, 26.44 ± 25.82 ng/g ww) and young (26.81 ± 10.67 ng/g ww) compared to males (8.88 ± 5.76 ng/g ww, p < 0.001), and significantly related to reduced body condition scores (p < 0.001). Concentrations of Se and albumin were significantly greater in males than females (whole blood Se, males, 42.34 pmol/g ww; females, 36.25 ± 6.27 pmol/g ww, p = 0.019; albumin, males, 4.34 ± 0.34 g/dl, females, 4.10 ± 0.29 g/dL, p = 0.018). Glutathione peroxidase activity ranged from 109.1 – 207.8 mU/mg hemoglobin, but did not differ significantly by sex or age (p > 0.08). Thyroid hormones were greater in females (solitary females and females with cubs) compared to males (p < 0.001). Biomarkers of Se status and concentrations of T3 were significantly positively related to Hg in all prime aged polar bears (p < 0.03). Albumin concentrations were significantly positively related to total TT4, and significantly negatively related to concentrations of ΣPCB7 (p < 0.003). Total thyroxine (TT4) was significantly negatively associated with blood concentrations of ΣPCB7 in solitary females (p = 0.045). These data suggest that female polar bears were more susceptible to changes in blood-based biomarkers of selenium and thyroid status than males. Further classifications of the physiologic states of polar bears and repeated measures of individuals over time are needed to accurately assess the biological impact of combined toxicant exposures. PMID:21903210

  9. CRABS IN CRISIS:BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND VULNERABILITIES TO CLIMATE CHANGE OF BRACHYURAN AND LITHODID CRABS FROM THE GULF OF CALIFORNIA TO THE BEAUFORT SEA

    EPA Science Inventory

    To predict the relative vulnerability of near-coastal species to climate change we analyzed the biogeographic and abundance patterns of the brachyuran or ‘True’ crabs (n=368) and lithodid or ‘King’ crabs (n=20) that are found in the twelve MEOW (“Mar...

  10. BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND VULNERABILITIES TO CLIMATE CHANGE OF BRACHYURAN AND LITHODID CRABS FROM THE GULF OF CALIFORNIA TO THE BEAUFORT SEA - 9-19-2014

    EPA Science Inventory

    As part of an EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change we analyzed the biogeographic and abundance patterns of the brachyuran or ‘True’ crabs (n=368) and lithodid or ‘King’ crabs (n=20) that are found...

  11. BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND VULNERABILITIES TO CLIMATE CHANGE OF BRACHYURAN AND LITHODID CRABS FROM THE GULF OF CALIFORNIA TO THE BEAUFORT SEA

    EPA Science Inventory

    As part of an EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change we analyzed the biogeographic and abundance patterns of the brachyuran or ‘True’ crabs (n=368) and lithodid or ‘King’ crabs (n=20) that are found...

  12. MIZMAS: Modeling the Evolution of Ice Thickness and Floe Size Distributions in the Marginal Ice Zone of the Chukchi and Beaufort Seas

    DTIC Science & Technology

    2013-09-30

    N. LeGrande, J. Lerner, J. Marshall, S. Menon, V. Oinas, J. Perlwitz, M. J. Puma , D. Rind, A. Romanou, G. L. Russell, M. Sato, D. T. Shindell, S...A. Lacis, A. N. LeGrande, J. Lerner, K. K. Lo, S. Menon, V. Oinas, J. Perlwitz, M. J. Puma , D. Rind, A. Romanou, M. Sato, D. T. Shindell, S. Sun, K...Miller, V. Oinas, A. Oloso, J. Perlwitz, M. J. Puma , W. M. Putman, D. Rind, A. Romanou, M. Sato, D. T. Shindell, S. Sun, R. Syed, N. Tausnev, K

  13. 33 CFR 147.T17-0024 - Safety Zone; NOBLE DISCOVERER, Outer Continental Shelf Drillship, Chukchi and/or Beaufort Seas...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Lease No. Latitude Longitude Burger A Posey 6764 OCS-Y-2280 N71° 18′ 30.92″ W163° 12′ 43.17″ Burger F Posey 6714 OCS-Y-2267 N71° 20′ 13.96″ W163° 12′ 21.75″ Burger J Posey 6912 OCS-Y-2321 N71° 10′ 24.03″ W163° 28′ 18.52″ Burger R Posey 6812 OCS-Y-2294 N71° 16′ 06.57″ W163° 30′ 39.44″ Burger S Posey...

  14. River Water and Brine Inventory over the Laptev Sea Shelf: 2007 To 2011

    NASA Astrophysics Data System (ADS)

    Thibodeau, B.; Bauch, D.

    2014-12-01

    Five years of oxygen isotope and hydrological survey reveal interannual variations in the inventory and distribution of river water over the Laptev Sea. Our results suggest that the Arctic Dipole Anomaly might connect the Laptev Sea river water inventory and the global Arctic freshwater inventory. In 2007, 2009 and 2010 relatively low amount of river water (≤1500 km3) was found and was mostly located in the southeastern Laptev Sea. In 2008 and 2011, high amounts of river water (~1600 km3 and ~2000 km3) were found, especially in the central and northern part of the shelf, suggesting a northward export of this water. It has been suggested that atmospheric forcing mainly controls the Laptev Sea summer surface hydrography and for this period, the interannual variability or summer river water inventory is coherent with the summer Arctic Dipole index. This could suggest that the Arctic Dipole has been a dominant forcing controlling the distribution and the fate of river water discharged within the Laptev Sea over the 2007-2011 period, which is concurrent with the recently highlighted persistent shift in early summer Arctic atmospheric circulation (Overland et al., 2012, GRL 39, L19804). The variation in river water inventory over the Laptev Sea Shelf is also positively related with recent Arctic Basin and Beaufort Gyre freshwater inventory (with a 2-yrs lag), which suggest that the river water originating from the Laptev Sea have an impact on the global Arctic freshwater inventory. During the same period the brine inventory was also variable but was dissociated from the river water inventory variation suggesting that, during this period different forcing was influencing the brine inventory.

  15. Arctic sea-ice variability during the 4th IPY and beyond

    NASA Astrophysics Data System (ADS)

    Gascard, J. J.

    2009-12-01

    that sea-ice thickness at a time of sea-ice thinning, is a dominant factor affecting sea-ice extent and also sea-ice mobility and break up. Earlier break up of sea-ice opening more leads capturing more sunlight is a dominant factor for enhancing sea-ice melting. Surface and bottom melting of sea-ice were highly spatially variable as observed during recent years including IPY. Bottom melting of sea-ice was very strong in the southern Beaufort Sea and quite small in the vicinity of the North Pole. Ocean heat flux for melting sea-ice is twofold: one part comes from absorption by the ocean mixed layer of solar heating through leads and open waters between ice floes. Another part might come from advection of warm water masses originating from the Pacific (shallow) and from the Atlantic (deep) and possibly influencing bottom sea ice melting. This effect was also highly spatially variable and mostly controlled by topography. It is important to notice that the 3 most recent years were characterized by the 3 most pronounced Arctic sea-ice extent minimum corresponding to half the extent of Arctic sea-ice 20 years ago. Combined with a thinning of 50% on average of Arctic sea-ice that would correspond to a 75% mass reduction of sea-ice. Is that not a relevant definition for a tipping point?

  16. Physical Characteristics and Geobiology of 'Rotten' Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Frantz, C. M.; Light, B.; Orellana, M. V.; Carpenter, S.; Junge, K.

    2015-12-01

    Arctic sea ice in its final stage of demise, "rotten ice", is characterized by seriously compromised structural integrity, making it difficult to collect and study. Consequently, little is known about the physical, chemical and biological properties of this ice type. Yet, as the Arctic melt season lengthens, this ice type will likely appear sooner and become more prevalent in the Arctic Ocean and its occurrence may be more common than satellite mapping and ice charts suggest (e.g., Barber et al., 2009). Here we present physical, chemical, biological, and optical measurements of first-year ice near Barrow, Alaska during the spring and summer of 2015. Samples represent a progression from solid, "springtime" shorefast ice (May); through melting, heavily melt-ponded, "summertime" shorefast ice (June); to the final stage of barely-intact, "rotten" ice collected from small floes Beaufort Sea (July). Results indicate that rotten ice exhibits low salinity, is well drained and has a lower density than its springtime counterpart. X-ray tomography of dimethyl phthalate-casted sea ice samples indicates differences in porosity and relative permeability in rotten ice vs. spring- and summertime ice. We also present a preliminary characterization of rotten sea ice as a microbial habitat using preliminary results of chemical measurements (nutrients, dissolved organic and inorganic carbon), and microbiological characterizations (concentrations and16S/18S rDNA-based identifications) from seawater vs. sea ice vs. sea ice brines. Optical measurements show that while decreased ice thickness and increased melt pond coverage cause an overall increase in solar radiation to the ocean as sea ice warms, rotten ice is actually less transparent to solar radiation than its spring- and summertime counterparts. These factors determine solar heating in the ocean and, ultimately, the potential for accelerated ice melting (e.g., Light et al., 2008). This work provides a foundation for understanding

  17. Mercury uptake within an ice algal community during the spring bloom in first-year Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Burt, Alexis; Wang, Feiyue; Pućko, Monika; Mundy, Christopher-John; Gosselin, Michel; Philippe, Benoît; Poulin, Michel; Tremblay, Jean-Éric; Stern, Gary A.

    2013-09-01

    In this study, we examine mercury bioaccumulation by a first-year sea-ice (FYI) algal community in the western Canadian Arctic during the spring of 2008. Total mercury concentration in bottom sea-ice particulate ([PHg]T) ranged 0.004-0.022 µg/g dw and was limited by the amount of mercury available for uptake when the spring bloom commenced. Mercury in ice algae originated from a combination of brine and seawater as sources, while atmospheric mercury depletion events did not appear to significantly contribute as a source in a coupled manner. We show that the bottom sea-ice brine presents a chemically and biologically unique niche from which inorganic Hg makes its way into the food web. Once incorporated into algae, mercury can be transported spatially and trophically within the ecosystem by a range of processes including grazing, resuspension, remineralization, and sedimentation. Ice algae contribute 10-60% of the annual primary production in the Arctic and are thought to become even more productive and abundant under a mild climate change scenario. Replacement of multiyear ice with FYI in the Beaufort Sea alone could result in an additional influx of ˜48 kg/yr of particle bound Hg. Further studies are thus warranted to elucidate mechanisms by which mercury transformation processes and transfer into the Arctic marine food web are impacted by the interaction between sea ice, brine, and seawater.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  19. Visible and thermal imaging of sea ice and open water from Coast Guard Arctic Domain Awareness flights

    NASA Astrophysics Data System (ADS)

    Chickadel, C. C.; Lindsay, R. W.; Clark, D.

    2014-12-01

    An uncooled thermal camera (microbolometer) and RGB camera were mounted in the tail section of a US Coast Guard HC-130 to observe sea ice, open water, and cloud tops through the open rear cargo doors during routine Arctic Domain Awareness (ADA) flights. Recent flights were conducted over the Beaufort Sea in June, July, and August of 2014, with flights planned for September and October. Thermal and visible images were collected at low altitude (100m) during times when the cargo doors were open and recorded high resolution information on ice floes, melt ponds, and surface temperature variability associated with the marginal ice zone (MIZ). These observations of sea ice conditions and surface water temperatures will be used to characterize floe size development and the temperature and albedo of ice ponds and leads. This information will allow for a detailed characterization of sea ice that can be used in process studies and for model evaluation, calibration of satellite remote sensing products, and initialization of sea ice prediction schemes.

  20. Effects of changing sea ice on marine mammals and subsistence hunters in northern Alaska from traditional knowledge interviews

    PubMed Central

    Quakenbush, Lori T.; Nelson, Mark

    2016-01-01

    Marine mammals are important sources of food for indigenous residents of northern Alaska. Changing sea ice patterns affect the animals themselves as well as access to them by hunters. Documenting the traditional knowledge of Iñupiaq and Yupik hunters concerning marine mammals and sea ice makes accessible a wide range of information relevant to understanding the ecosystem to which humans belong. We interviewed hunters in 11 coastal villages from the northern Bering Sea to the Beaufort Sea. Hunters reported extensive changes in sea ice and weather that have affected the timing of marine mammal migrations, their distribution and behaviour and the efficacy of certain hunting methods. Amidst these changes, however, hunters cited offsetting technological benefits, such as more powerful and fuel-efficient outboard engines. Other concerns included potential impacts to subsistence hunting from industrial activity such as shipping and oil and gas development. While hunters have been able to adjust to some changes, continued environmental changes and increased disturbance from human activity may further challenge their ability to acquire food in the future. There are indications, however, that innovation and flexibility provide sources of resilience. PMID:27555644

  1. Effects of changing sea ice on marine mammals and subsistence hunters in northern Alaska from traditional knowledge interviews.

    PubMed

    Huntington, Henry P; Quakenbush, Lori T; Nelson, Mark

    2016-08-01

    Marine mammals are important sources of food for indigenous residents of northern Alaska. Changing sea ice patterns affect the animals themselves as well as access to them by hunters. Documenting the traditional knowledge of Iñupiaq and Yupik hunters concerning marine mammals and sea ice makes accessible a wide range of information relevant to understanding the ecosystem to which humans belong. We interviewed hunters in 11 coastal villages from the northern Bering Sea to the Beaufort Sea. Hunters reported extensive changes in sea ice and weather that have affected the timing of marine mammal migrations, their distribution and behaviour and the efficacy of certain hunting methods. Amidst these changes, however, hunters cited offsetting technological benefits, such as more powerful and fuel-efficient outboard engines. Other concerns included potential impacts to subsistence hunting from industrial activity such as shipping and oil and gas development. While hunters have been able to adjust to some changes, continued environmental changes and increased disturbance from human activity may further challenge their ability to acquire food in the future. There are indications, however, that innovation and flexibility provide sources of resilience.

  2. Airborne Surveys of Snow Depth over Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Panzer, B.; Leuschen, C.; Pang, S.; Markus, T.; Holt, B.; Gogineni, S.

    2011-01-01

    During the spring of 2009, an ultrawideband microwave radar was deployed as part of Operation IceBridge to provide the first cross-basin surveys of snow thickness over Arctic sea ice. In this paper, we analyze data from three approx 2000 km transects to examine detection issues, the limitations of the current instrument, and the regional variability of the retrieved snow depth. Snow depth is the vertical distance between the air \\snow and snow-ice interfaces detected in the radar echograms. Under ideal conditions, the per echogram uncertainty in snow depth retrieval is approx 4 - 5 cm. The finite range resolution of the radar (approx 5 cm) and the relative amplitude of backscatter from the two interfaces limit the direct retrieval of snow depths much below approx 8 cm. Well-defined interfaces are observed over only relatively smooth surfaces within the radar footprint of approx 6.5 m. Sampling is thus restricted to undeformed, level ice. In early April, mean snow depths are 28.5 +/- 16.6 cm and 41.0 +/- 22.2 cm over first-year and multiyear sea ice (MYI), respectively. Regionally, snow thickness is thinner and quite uniform over the large expanse of seasonal ice in the Beaufort Sea, and gets progressively thicker toward the MYI cover north of Ellesmere Island, Greenland, and the Fram Strait. Snow depth over MYI is comparable to that reported in the climatology by Warren et al. Ongoing improvements to the radar system and the utility of these snow depth measurements are discussed.

  3. A New Sea Ice Model: Pancakes to Metrics

    NASA Technical Reports Server (NTRS)

    Coon, M.; Kwok, R.; Pruis, M.; Levy, G.; Schreyer, H. L.; Sulsky, D.; Toudal, L.

    2007-01-01

    We are developing, testing, and validating a new sea ice dynamics model that treats the ice cover as an elastic/decohesive material in the permanent pack and includes the correct frazil/pancake behavior in the marginal zone. Two salient features of present ice dynamics models are that they do not: 1) reproduce the oriented fracture patterns of openings and closings in the pack ice, and 2) accurately model the effects of frazil/pancake ice formation in the ice margin. These poorly modeled areas account for a substantial portion of the ice growth, turbulent heat flux to the atmosphere, salt flux to the ocean, and energy dissipation due to slippage, ridging, and rafting, in the Arctic. Existing sea ice models have shown limited success in predicting the degree to which a lead will open for prescribed or observed forcing conditions. An important aspect of the new model we are developing is that the existence of cracks, along with their orientation, opening, and closing, is predicted. To put this effort in perspective a short history of ice dynamics modeling and data collection is presented. The RGPS data set is used to validate the model. As part of the testing and validation of the model, we are working on a new metric for comparing linear features (leads and ridges) in the data and model to be used in data assimilation for this model. The model framework is presented as well as some results showing the creation and development of leads in a simulation of ice dynamics in the Beaufort Sea. Other presentations by the authors will show other results from this effort.

  4. Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996

    SciTech Connect

    Dong, Xiquan; Zib, Benjamin J.; Xi, Baike; Stanfield, Ryan; Deng, Yi; Zhang, Xiangdong; Lin, B.; Long, Charles N.

    2013-08-29

    A warming Arctic climate is undergoing significant e 21 nvironmental change, most evidenced by the reduction of Arctic sea-ice extent during the summer. In this study, we examine two extreme anomalies of September sea-ice extent in 2007 and 1996, and investigate the impacts of cloud fraction (CF), atmospheric precipitable water vapor (PWV), downwelling longwave flux (DLF), surface air temperature (SAT), pressure and winds on the sea-ice variation in 2007 and 1996 using both satellite-derived sea-ice products and MERRA reanalysis. The area of the Laptev, East Siberian and West Chukchi seas (70-90oN, 90-180oE) has experienced the largest variation in sea-ice extent from year-to-year and defined here as the Area Of Focus (AOF). The record low September sea-ice extent in 2007 was associated with positive anomalies 30 of CF, PWV, DLF, and SAT over the AOF. Persistent anti-cyclone positioned over the Beaufort Sea coupled with low pressure over Eurasia induced easterly zonal and southerly meridional winds. In contrast, negative CF, PWV, DLF and SAT anomalies, as well as opposite wind patterns to those in 2007, characterized the 1996 high September sea-ice extent. Through this study, we hypothesize the following positive feedbacks of clouds, water vapor, radiation and atmospheric variables on the sea-ice retreat during the summer 2007. The record low sea-ice extent during the summer 2007 is initially triggered by the atmospheric circulation anomaly. The southerly winds across the Chukchi and East Siberian seas transport warm, moist air from the north Pacific, which is not only enhancing sea-ice melt across the AOF, but also increasing clouds. The positive cloud feedback results in higher SAT and more sea-ice melt. Therefore, 40 more water vapor could be evaporated from open seas and higher SAT to form more clouds, which will enhance positive cloud feedback. This enhanced positive cloud feedback will then further increase SAT and accelerate the sea-ice retreat during the

  5. Gene flow on ice: the role of sea ice and whaling in shaping Holarctic genetic diversity and population differentiation in bowhead whales (Balaena mysticetus)

    PubMed Central

    Elizabeth Alter, S; Rosenbaum, Howard C; Postma, Lianne D; Whitridge, Peter; Gaines, Cork; Weber, Diana; Egan, Mary G; Lindsay, Melissa; Amato, George; Dueck, Larry; Brownell, Robert L; Heide-Jørgensen, Mads-Peter; Laidre, Kristin L; Caccone, Gisella; Hancock, Brittany L

    2012-01-01

    Sea ice is believed to be a major factor shaping gene flow for polar marine organisms, but it remains unclear to what extent it represents a true barrier to dispersal for arctic cetaceans. Bowhead whales are highly adapted to polar sea ice and were targeted by commercial whalers throughout Arctic and subarctic seas for at least four centuries, resulting in severe reductions in most areas. Both changing ice conditions and reductions due to whaling may have affected geographic distribution and genetic diversity throughout their range, but little is known about range-wide genetic structure or whether it differed in the past. This study represents the first examination of genetic diversity and differentiation across all five putative stocks, including Baffin Bay-Davis Strait, Hudson Bay-Foxe Basin, Bering-Beaufort-Chukchi, Okhotsk, and Spitsbergen. We also utilized ancient specimens from Prince Regent Inlet (PRI) in the Canadian Arctic and compared them with modern stocks. Results from analysis of molecular variance and demographic simulations are consistent with recent and high gene flow between Atlantic and Pacific stocks in the recent past. Significant genetic differences between ancient and modern populations suggest PRI harbored unique maternal lineages in the past that have been recently lost, possibly due to loss of habitat during the Little Ice Age and/or whaling. Unexpectedly, samples from this location show a closer genetic relationship with modern Pacific stocks than Atlantic, supporting high gene flow between the central Canadian Arctic and Beaufort Sea over the past millennium despite extremely heavy ice cover over much of this period. PMID:23170222

  6. Trends in the breeding population of Adélie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

    PubMed

    Lyver, Phil O'B; Barron, Mandy; Barton, Kerry J; Ainley, David G; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R

    2014-01-01

    Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then.

  7. Gene flow on ice: the role of sea ice and whaling in shaping Holarctic genetic diversity and population differentiation in bowhead whales (Balaena mysticetus).

    PubMed

    Elizabeth Alter, S; Rosenbaum, Howard C; Postma, Lianne D; Whitridge, Peter; Gaines, Cork; Weber, Diana; Egan, Mary G; Lindsay, Melissa; Amato, George; Dueck, Larry; Brownell, Robert L; Heide-Jørgensen, Mads-Peter; Laidre, Kristin L; Caccone, Gisella; Hancock, Brittany L

    2012-11-01

    Sea ice is believed to be a major factor shaping gene flow for polar marine organisms, but it remains unclear to what extent it represents a true barrier to dispersal for arctic cetaceans. Bowhead whales are highly adapted to polar sea ice and were targeted by commercial whalers throughout Arctic and subarctic seas for at least four centuries, resulting in severe reductions in most areas. Both changing ice conditions and reductions due to whaling may have affected geographic distribution and genetic diversity throughout their range, but little is known about range-wide genetic structure or whether it differed in the past. This study represents the first examination of genetic diversity and differentiation across all five putative stocks, including Baffin Bay-Davis Strait, Hudson Bay-Foxe Basin, Bering-Beaufort-Chukchi, Okhotsk, and Spitsbergen. We also utilized ancient specimens from Prince Regent Inlet (PRI) in the Canadian Arctic and compared them with modern stocks. Results from analysis of molecular variance and demographic simulations are consistent with recent and high gene flow between Atlantic and Pacific stocks in the recent past. Significant genetic differences between ancient and modern populations suggest PRI harbored unique maternal lineages in the past that have been recently lost, possibly due to loss of habitat during the Little Ice Age and/or whaling. Unexpectedly, samples from this location show a closer genetic relationship with modern Pacific stocks than Atlantic, supporting high gene flow between the central Canadian Arctic and Beaufort Sea over the past millennium despite extremely heavy ice cover over much of this period.

  8. Trends in the Breeding Population of Adélie Penguins in the Ross Sea, 1981–2012: A Coincidence of Climate and Resource Extraction Effects

    PubMed Central

    Lyver, Phil O’B.; Barron, Mandy; Barton, Kerry J.; Ainley, David G.; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R.

    2014-01-01

    Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981–2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of −0.019 during 1981–2000, followed by a positive per capita growth rate of 0.067 for 2001–2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then. PMID:24621601

  9. A brief lithostratigraphic review of the Abrahamskraal and Koonap formations of the Beaufort Group, South Africa: Towards a basin-wide stratigraphic scheme for the Middle Permian Karoo

    NASA Astrophysics Data System (ADS)

    Day, Michael Oliver; Rubidge, Bruce Sidney

    2014-12-01

    The basal strata of the Beaufort Group of the South African Karoo Basin, comprising the western Abrahamskraal and eastern Koonap formations, contain the most time extensive record of Middle Permian fossil tetrapods and hold the key to understanding Middle Permian biodiversity change in the continental realm. To determine faunal stratigraphic ranges a reliable lithostratigraphic framework for Middle Permian Beaufort deposits is essential. Until now this has proved difficult to achieve, largely due to the homogeneity of the fluvial succession coupled with structural complexity as a result of Cape Fold Belt orogenesis. Accordingly, the Abrahamskraal Formation has been only locally subdivided on the basis of sandstone packages but regional stratigraphic subdivision has not yet achieved satisfactorily. Collation of stratigraphic sections from around the Karoo Basin for this study demonstrates the presence of four sandstone packages are present within the Abrahamskraal Formation in the south-western corner of the basin. These sandstone packages are given member status, based upon the nomenclature of Le Roux (1985) with the addition of the newly recognised Grootfontein Member. The Combrinkskraal and Grootfontein Members occur in the lower half of the Abrahamskraal Formation and are laterally persistent along the southern margin of the basin. The Koornplaats Member is more restricted to the south west corner of the basin, where it quite thick, suggesting the narrowing of the highly channelized area. The overlying Moordenaars Member, more extensive towards the north than underlying packages, indicates subsequent northwesterly expansion of the locus of active channelization with time. Although thin sandstone packages in the more easterly positioned and stratigraphically equivalent Koonap Formation, this does not facilitate lithostratigraphic subdivision of this part of the stratigraphic succession and may indicate a different form of fluvial architecture. Our study provides

  10. Melting Ice, Rising Seas

    NASA Video Gallery

    Sea level rise is an indicator that our planet is warming. Much of the world's population lives on or near the coast, and rising seas are something worth watching. Sea level can rise for two reason...

  11. Mammals of the Sea.

    ERIC Educational Resources Information Center

    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)

  12. Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Cavalieri, Donald J.

    2005-01-01

    Sea ice covers vast areas of the polar oceans, with ice extent in the Northern Hemisphere ranging from approximately 7 x 10(exp 6) sq km in September to approximately 15 x 10(exp 6) sq km in March and ice extent in the Southern Hemisphere ranging from approximately 3 x 10(exp 6) sq km in February to approximately 18 x 10(exp 6) sq km in September. These ice covers have major impacts on the atmosphere, oceans, and ecosystems of the polar regions, and so as changes occur in them there are potential widespread consequences. Satellite data reveal considerable interannual variability in both polar sea ice covers, and many studies suggest possible connections between the ice and various oscillations within the climate system, such as the Arctic Oscillation, North Atlantic Oscillation, and Antarctic Oscillation, or Southern Annular Mode. Nonetheless, statistically significant long-term trends are also apparent, including overall trends of decreased ice coverage in the Arctic and increased ice coverage in the Antarctic from late 1978 through the end of 2003, with the Antarctic ice increases following marked decreases in the Antarctic ice during the 1970s. For a detailed picture of the seasonally varying ice cover at the start of the 21st century, this chapter includes ice concentration maps for each month of 2001 for both the Arctic and the Antarctic, as well as an overview of what the satellite record has revealed about the two polar ice covers from the 1970s through 2003.

  13. Mapping wave heights in sea ice with Sentinel 1

    NASA Astrophysics Data System (ADS)

    Stopa, Justin; Ardhuin, Fabrice; Collard, Fabrice; Mouche, Alexis; Guitton, Gilles; Sutherland, Peter

    2016-04-01

    Sea ice plays an important role in the Earth system by regulating air-sea fluxes. These fluxes can be enhanced by the breaking of ice into floes which critically depends on wave heights propagating across the ice. Remote sensing with SAR provides a unique coverage of the polar regions but so far the measurement of wave heights has been performed routinely only for open water. The presence of ice completely changes the mechanisms by which waves make patterns in radar images. Namely, in the open ocean, the constructed images appear blurred due to the fact that the high frequency waves are unresolved by the sensor. Instead, in ice-covered seas, high frequency waves have been dissipated or scattered away, and only the low-frequency swell components are observed. Two new algorithms have been proposed by Ardhuin et al. (2015). Refining these algorithms, we analyze the intricate wave patterns captured over sea ice by Sentinel 1-A, and measure both the wave heights and directional spreading of the wave spectrum. The procedure is a two-step process which uses an estimation of the orbital vertical velocities that produce the observed image intensity. The first step is implemented when wiggly lines are present. Wiggly lines are created by the presence of two swell systems and are removed by estimating the wave orbital velocity that causes the amplitude in the wiggly line. The second step uses Fourier analysis to invert the straightened image into a velocity field. As a result we obtain a full non-linear inversion the mapping from the velocity field to the SAR intensity image. The inverted velocities can be used to obtain the wavenumber-direction spectrum. Our algorithm is applied to S1A images from the Arctic and Antarctic and discussions follow in terms of wave-ice interaction. These data will be validated using in situ measurements from the ONR Sea State DRI (Beaufort sea, 2016), and combined with numerical modeling using the WAVEWATCH III model to adjust parameterization

  14. NASA Sea Ice Validation Program for the Defense Meteorological Satellite Program Special Sensor Microwave Imager

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J. (Editor); Crawford, John P.; Drinkwater, Mark R.; Emery, William J.; Eppler, Duane T.; Farmer, L. Dennis; Fowler, Charles W.; Goodberlet, Mark; Jentz, Robert R.; Milman, Andrew

    1992-01-01

    The history of the program is described along with the SSM/I sensor, including its calibration and geolocation correction procedures used by NASA, SSM/I data flow, and the NASA program to distribute polar gridded SSM/I radiances and sea ice concentrations (SIC) on CD-ROMs. Following a discussion of the NASA algorithm used to convert SSM/I radiances to SICs, results of 95 SSM/I-MSS Landsat IC comparisons for regions in both the Arctic and the Antarctic are presented. The Landsat comparisons show that the overall algorithm accuracy under winter conditions is 7 pct. on average with 4 pct. negative bias. Next, high resolution active and passive microwave image mosaics from coordinated NASA and Navy aircraft underflights over regions of the Beaufort and Chukchi seas in March 1988 were used to show that the algorithm multiyear IC accuracy is 11 pct. on average with a positive bias of 12 pct. Ice edge crossings of the Bering Sea by the NASA DC-8 aircraft were used to show that the SSM/I 15 pct. ice concentration contour corresponds best to the location of the initial bands at the ice edge. Finally, a summary of results and recommendations for improving the SIC retrievals from spaceborne radiometers are provided.

  15. On evaluating the accuracy of SAR sea-ice classification using multifrequency polarimetric AIRSAR data

    NASA Technical Reports Server (NTRS)

    Drinkwater, Mark R.; Rignot, Eric

    1993-01-01

    We investigate how multifrequency and polarimetric synthetic aperture radar (SAR) imagery enhances present capability to discriminate different ice conditions in single-frequency, single-polarization satellite SAR data. Frequencies considered are C- (lambda = 5.6cm), L- (lambda = 24cm) and P- (lambda = 68cm) band. Radar backscatter characteristics of six radiometrically and polarimetrically distinct ice types are selected from a cluster analysis of the multifrequency polarimetric SAR data and used to classify SAR images. Validation of these ice conditions is based on information provided by aerial photos, weather and ice surface measurements acquired at an ice camp, together with airborne passive microwave imagery, and visual analysis of the SAR data. The six identified sea-ice types are: (1) multiyear sea-ice; (2) compressed first year ice; (3) first year rubble and ridges; (4) first year rough ice; (5) first year smooth ice; and (6) thin ice. Open water is absent in all analyzed data. Classification of the SAR imagery into those six ice types is performed using a Bayesian Maximum A Posteriori classifier. Two complete scenes acquired at different dates in different locations are classified. The scenes were chosen such that they are representative of typical ice conditions in the Beaufort Sea in March 1988 and because ancillary information is available for validating the segmentation of various ice surface conditions.

  16. Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes

    USGS Publications Warehouse

    Fischbach, A.S.; Amstrup, Steven C.; Douglas, D.C.

    2007-01-01

    Polar bears (Ursus maritimus) in the northern Alaska region den in coastal areas and on offshore drifting ice. We evaluated changes in the distribution of polar bear maternal dens between 1985 and 2005, using satellite telemetry. We determined the distribution of maternal dens occupied by 89 satellite collared female polar bears between 137°W and 167°W longitude. The proportion of dens on pack ice declined from 62% in 1985–1994 to 37% in 1998–2004 (P = 0.044) and among pack ice dens fewer occurred in the western Beaufort Sea after 1998. We evaluated whether hunting, attraction to bowhead whale remains, or changes in sea ice could explain changes in den distribution. We concluded that denning distribution changed in response to reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season. In consort, these changes have likely reduced the availability and quality of pack ice denning habitat. Further declines in sea ice availability are predicted. Therefore, we expect the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the Alaska coast in advance of denning.

  17. Near Real Time Sea Ice Thickness from the CryoSat-2 Satellite, and the application of a time-varying snow load

    NASA Astrophysics Data System (ADS)

    Tilling, R.; Ridout, A.; Shepherd, A.; Muir, A.

    2015-12-01

    Since October 2010, data from the European Space Agency (ESA) CryoSat-2 (CS-2) satellite has provided the means to produce sea ice thickness maps across the entire Arctic Ocean basin. These large-scale observations of Arctic sea ice thickness are required to determine trends, compare hemispheres and aid predictive models of future global climate change. However, the final ESA data product is not available until ~30 days after the satellite acquisition, and as such the use of the data for near real time (NRT), operational purposes, has not been possible. At University College London (UCL) we now produce the first NRT estimates of Arctic sea ice thickness, with a lag of only 2 days, using NRT data that has recently been released by ESA. This original, operational dataset will benefit industries such as transport and tourism, as well as the scientific community. This presentation will summarise the NRT product and the data that is avilable, investigate the differences between the NRT and final product, and analyse its reliability and data coverage in particular regions of interest (e.g. the Northwest Passage, and the Beaufort Sea). We have also developed an Arctic-wide, time-varying snow load, so that our CryoSat-2 sea ice processing no longer relies on a constant monthly snow climatology. This presentation will summarise the development, application, and benefits of the new snow load in relation to our NRT and final sea ice thickness estimates.

  18. Relative sea level and coastal environments in arctic Alaska during Marine Isotope Stage 5

    NASA Astrophysics Data System (ADS)

    Farquharson, L. M.; Mann, D. H.; Jones, B. M.; Rittenour, T. M.; Grosse, G.; Groves, P.

    2015-12-01

    Marine Isotope Stage (MIS) 5 was characterized by marked fluctuations in climate, the warmest being MIS 5e (124-119 ka) when relative sea level (RSL) stood 2-10 m higher than today along many coastlines. In northern Alaska, marine deposits now 5-10 m above modern sea level are assigned to this time period and termed the Pelukian transgression (PT). Complicating this interpretation is the possibility that an intra-Stage 5 ice shelf extended along the Alaskan coast, causing isostatic depression along its grounded margins, which caused RSL highs even during periods of low, global RSL. Here we use optically stimulated luminescence (OSL) to date inferred PT deposits on the Beaufort Sea coastal plain. A transition from what we interpret to be lagoonal mud to sandy tidal flat deposits lying ~ 2.75 m asl dates to 113+/-18 ka. Above this, a 5-m thick gravelly barrier beach dates to 95 +/- 20 ka. This beach contains well-preserved marine molluscs, whale vertebrae, and walrus tusks. Pleistocene-aged ice-rich eolian silt (yedoma) blanket the marine deposits and date to 57.6 +/-10.9 ka. Our interpretation of this chronostratigraphy is that RSL was several meters higher than today during MIS 5e, and lagoons or brackish lakes were prevalent. Gravel barrier beaches moved onshore as local RSL rose further after MIS 5e. The error range of the OSL age of the barrier-beach unit spans the remaining four substages of MIS 5; however, the highstand of RSL on this arctic coastline appears to occurr after the warmest part of the last interglacial and appears not to be coeval with the eustatic maximum reached at lower latitudes during MIS 5. One possibility is that RSL along the Beaufort Sea coast was affected by isostatic depression caused by an ice shelf associated with widespread, intra-Stage 5 glaciation that was out of phase with lower latitude glaciation and whose extent and timing remains enigmatic.

  19. Wind-driven interannual variability of sea ice algal production in the western Arctic Chukchi Borderland

    NASA Astrophysics Data System (ADS)

    Watanabe, E.; Onodera, J.; Harada, N.; Aita, M. N.; Ishida, A.; Kishi, M. J.

    2015-10-01

    Seasonal and interannual variability in the biogenic particle sinking flux was recorded using multi-year bottom-tethered sediment trap mooring systems in the Northwind Abyssal Plain (Station NAP: 75° N, 162° W, 1975 m water depth) of the western Arctic Chukchi Borderland. Trapped particle flux at a median depth of 184 m had an obvious peak and dominance of sea ice-related diatom assemblages in August 2011. The observed particle flux was considerably suppressed throughout summer 2012. In the present study, the response of ice algal production and biomass to wind-driven changes in the physical environment was addressed using a pan-Arctic sea ice-ocean modeling approach. A sea ice ecosystem with ice algae was newly incorporated into the lower-trophic marine ecosystem model, which was previously coupled with a high-resolution (i.e., 5 km horizontal grid size) sea ice-ocean general circulation model. Seasonal model experiments covering 2-year mooring periods indicated that primary productivity of ice algae around the Chukchi Borderland depended on basin-scale wind patterns via various processes. Easterly winds in the southern part of a distinct Beaufort High supplied nutrient-rich water for euphotic zones of the NAP region via both surface Ekman transport of Chukchi shelf water and vertical turbulent mixing with underlying nutricline water in 2011. In contrast, northwesterly winds flowing in the northern part of an extended Siberian High transported oligotrophic water within the Beaufort Gyre circulation toward the NAP region in 2012. The modeled ice algal biomass during summer reflected the differences in nutrient distribution. The modeled sinking flux of particulate organic nitrogen (PON) was comparable with the time series obtained from sediment trap data in summer 2011. In contrast, lateral advection of ice algal patches of shelf origin during a great cyclone event may have caused a modeled PON flux bias in 2012. Sensitivity experiments revealed several

  20. Eco-environmental implications of elemental and carbon isotope distributions in ornithogenic sediments from the Ross Sea region, Antarctica

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodong; Nie, Yaguang; Sun, Liguang; Emslie, Steven D.

    2013-09-01

    Seabirds have substantial influence on geochemical circulation of elements, serving as a link for substance exchange between their foraging area and colonies. In this study, we investigated the elemental and carbon isotopic composition of five penguin-affected sediment profiles excavated from Ross Island and Beaufort Island in the Ross Sea region, Antarctica. Among the three main constituents of the sediments (including weathered bedrock, guano and algae), guano was the main source of organic matter and nutrients, causing selective enrichment of several elements in each of the sediment profiles. In the 22 measured elements, As, Cd, Cu, P, S, Se and Zn were identified as penguin bio-elements in the Ross Sea region through statistical analysis and comparison with local end-member environmental media such as weathered bedrock, fresh guano and fresh algae. Carbon isotopic composition in the ornithogenic sediments showed a mixing feature of guano and algae. Using a two-member isotope mixing equation, we were able to reconstruct the historical change of guano input and algal bio-mass. Compared with research in other parts of Antarctic, Arctic, and South China Sea, we found apparent overlap of avian bio-elements including As, Cd, Cu, P, Se, and Zn. Information on the composition and behavior of bio-elements in seabird guano on a global scale, and the role that bio-vectors play in the geochemical circulation between land and sea, will facilitate future research on avian ecology and paleoclimatic reconstruction.

  1. Holocene Northern Hemisphere sea-ice distribution - proxy data reconstruction and modelling

    NASA Astrophysics Data System (ADS)

    Seidenkrantz, Marit-Solveig; de Vernal, Anne; Goosse, Hugues; Klein, François; Solignac, Sandrine; Van Nieuwenhove, Nicolas; Pearce, Christof; Caissie, Beth; Belt, Simon; Sha, Longbin; Cronin, Thomas M.; Stein, Rüdiger; Macias-Fauria, Marc; DeNinno, Lauren H.

    2016-04-01

    A strikingly fast decrease of Arctic sea-ice cover has been recorded for the instrumental period and attributed to anthropogenic climate change, but little is known about natural sea-ice variability. Hence, there is a need for longer sea-ice time series to establish a baseline for natural Arctic sea-ice variability. We compiled 120 proxy-based sea-ice reconstructions from the Arctic Ocean and subarctic marginal seas to evaluate the stability/variability of sea-ice cover during the Holocene. The reconstructions are primarily based on published data combined with a few yet-unpublished records of biological (diatoms, dinoflagellate cysts, foraminifera, ostracods), sedimentological (IRD), and biogeochemical (IP25, PIP25, TOC) sea-ice indicators. Each indicator and record has been interpreted independently. We present all data as long-term annual means (months of sea ice per year). Sea-ice reconstructions are grouped into these classes: perennial (11-12 month/yr), dense (6-10 m/yr), common (1-6 m/yr), occasional (0.1-1 m/yr), rare (almost never) and absent (never). Further, reconstructions are made for the time slices 0-2 cal. ka (BP), 2-4 ka, 4-6 ka, 6±0.5 ka, 6-8 ka and 8-10 ka. Our study shows that winter sea ice was present during the entire Holocene, but summer sea ice may have been somewhat reduced in some areas during the Holocene Climate Optimum (10-6 ka), with variations between basins. In the Nordic Seas and N Atlantic minimum sea-ice conditions are seen 10-6 ka, whereas in the eastern Labrador Sea minimum sea-ice occurred 6-4 ka. Since ~4 ka sea-ice cover has increased, especially in the most recent millennia. Changes are subtle, however, but nonetheless consistent. The Pacific sector of the Arctic (Bering, Chukchi, Beaufort, Laptev, Okhotsk seas) shows less variability during the Holocene, though it is noted that these records have poorer age control and resolution than those from the Atlantic sector. It is noteworthy that, within the available temporal

  2. Colorful Underwater Sea Creatures

    ERIC Educational Resources Information Center

    McCutcheon, Heather

    2011-01-01

    In this article, the author describes a project wherein students created colorful underwater sea creatures. This project began with a discussion about underwater sea creatures and how they live. The first step was making the multi-colored tissue paper that would become sea creatures and seaweed. Once students had the shapes of their sea creatures…

  3. Development of an autonomous sea ice tethered buoy for the study of ocean-atmosphere-sea ice-snow pack interactions: the O-buoy

    NASA Astrophysics Data System (ADS)

    Knepp, T. N.; Bottenheim, J.; Carlsen, M.; Carlson, D.; Donohoue, D.; Friederich, G.; Matrai, P. A.; Netcheva, S.; Perovich, D. K.; Santini, R.; Shepson, P. B.; Simpson, W.; Valentic, T.; Williams, C.; Wyss, P. J.

    2010-02-01

    A buoy based instrument platform (the "O-buoy") was designed, constructed, and field tested for year-round measurement of ozone, bromine monoxide, carbon dioxide, and meteorological variables over Arctic sea ice. The O-buoy operated in an autonomous manner with daily, bi-directional data transmissions using Iridium satellite communication. The O-buoy was equipped with three power sources: primary lithium-ion battery packs, rechargeable lead acid packs, and solar panels that recharge the lead acid packs, and can fully power the O-buoy during summer operation. This system was designed to operate under the harsh conditions present in the Arctic, with minimal direct human interaction, to aid in our understanding of the atmospheric chemistry that occurs in this remote region of the world. The current design requires approximately yearly maintenance limited by the lifetime of the primary power supply. The O-buoy system was field tested in Elson Lagoon, Barrow, Alaska from February to May 2009, and deployed in the Beaufort Sea in October 2009. Here, we describe the design and present preliminary data.

  4. Sea ice, erosion, and vulnerability of Arctic coasts

    NASA Astrophysics Data System (ADS)

    Barnhart, Katherine; Overeem, Irina; Kay, Jennifer; Anderson, Robert

    2015-04-01

    Coasts form the dynamic interface between the terrestrial and oceanic systems. In the Arctic, and in much of the world, the coast is a zone of relatively high population, infrastructure, biodiversity, and ecosystem services. A significant difference between Arctic and temperate coasts is the presence of sea ice. Sea ice influences Arctic coasts in two main ways: (1) the length of the sea ice-free season controls the length of time over which nearshore water can interact with the land, and (2) the location of the sea ice edge controls the fetch over which storm winds can blow over open water, resulting in changes in nearshore water level and wave field. The resulting nearshore hydrodynamic environment impacts all aspects of the coastal system. We first combine satellite records of sea ice with a simple model for wind-driven storm surge and waves to estimate how changes in the length and character of the sea ice-free season have impacted the nearshore hydrodynamic environment along Alaska's Beaufort Sea Coast for the period 1979-2012. This region has experienced some of the greatest changes in both sea ice cover and coastal erosion rates in the Arctic and is anticipated to experience significant change in the future. The median length of the 2012 open-water season along this stretch of coast, in comparison to 1979, expanded by 1.9 x. At the same time, coastal erosion rates increased from 8.7 m yr-1 to 19 m yr-1. At Drew Point, winds from the northwest result in increased water levels at the coast and control the process of submarine notch incision, the rate-limiting step of coastal retreat. When open-water conditions exist, the distance to the sea ice edge exerts control on the water level and wave field through its control on fetch. We find that the extreme values of water-level setup at Drew Point have increased consistently with increasing fetch. We then extend our analysis of the length of the open water season to the entire Arctic using both satellite

  5. Holocene Paleoceanography of the Chukchi Sea / Alaskan Margin, Western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    McKay, J. L.; Hillaire-Marcel, C.; de Vernal, A.; Polyak, L.; Darby, D.

    2006-12-01

    A multi-proxy approach to the analysis of deep-sea sediment cores has been used to investigate paleoceanographical changes in the western Arctic. This approach includes stable isotopic analysis of{ \\it Neogloboquadrina pachyderma} (Np), the dominant planktonic foraminifera in the Arctic, which lives along the pycnocline that separates the cold, low salinity surface water from the underlying warmer water mass of North Atlantic origin. Palynological analyses focus on dinocyst assemblages that are usually well preserved in Arctic seas and include several species, thus allowing treatment of data (modern analogue technique) for quantitative reconstruction of sea-surface parameters, including maximum summer temperature and seasonal extent of sea-ice cover (cf. de Vernal et al., Paleoceanography, 2005). Work in the Chukchi Sea has shown that larger (i.e., heavier, possibly mature) specimens of Np are characterized by a lower oxygen isotopic composition relative to smaller (i.e., possibly juvenile) specimens that live at shallower depths, reflecting calcification of larger Np shells on top of the warmer North Atlantic Water mass (cf. Hillaire-Marcel et al., Quat. Sci. Rev., 2004). These results suggest that a reverse thermocline (warmer water underlying colder water) persisted throughout the Holocene, and that the gradients between surface and subsurface waters were stronger during the early Holocene, which may indicate greater influx of North Atlantic Water at this time. It is also possible that the isotopic composition of the planktonic foraminifera was influenced by enhanced sea-ice formation and sinking of isotopically-light brines during the early Holocene. This second hypothesis is compatible with reconstructions from dinocysts that suggest maximum sea-ice extent during the early Holocene. Preliminary results from core HLY0501-05 collected in the Beaufort Sea off the Alaskan Margin during Leg 1 of the HOTRAX 2005 Expedition show results consistent with those of the

  6. Providing Real-time Sea Ice Modeling Support to the U.S. Coast Guard

    NASA Astrophysics Data System (ADS)

    Allard, Richard; Dykes, James; Hebert, David; Posey, Pamela; Rogers, Erick; Wallcraft, Alan; Phelps, Michael; Smedstad, Ole Martin; Wang, Shouping; Geiszler, Dan

    2016-04-01

    The Naval Research Laboratory (NRL) supported the U.S. Coast Guard Research Development Center (RDC) through a demonstration project during the summer and autumn of 2015. Specifically, a modeling system composed of a mesoscale atmospheric model, regional sea ice model, and regional wave model were loosely coupled to provide real-time 72-hr forecasts of environmental conditions for the Beaufort/Chukchi Seas. The system components included a 2-km regional Community Ice CodE (CICE) sea ice model, 15-km Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS) atmospheric model, and a 5-km regional WAVEWATCH III wave model. The wave model utilized modeled sea ice concentration fields to incorporate the effects of sea ice on waves. The other modeling components assimilated atmosphere, ocean, and ice observations available from satellite and in situ sources. The modeling system generated daily 72-hr forecasts of synoptic weather (including visibility), ice drift, ice thickness, ice concentration and ice strength for missions within the economic exclusion zone off the coast of Alaska and a transit to the North Pole in support of the National Science Foundation GEOTRACES cruise. Model forecasts graphics were shared on a common web page with selected graphical products made available via ftp for bandwidth limited users. Model ice thickness and ice drift show very good agreement compared with Cold Regions Research and Engineering Laboratory (CRREL) Ice Mass Balance buoys. This demonstration served as a precursor to a fully coupled atmosphere-ocean-wave-ice modeling system under development. National Ice Center (NIC) analysts used these model data products (CICE and COAMPS) along with other existing model and satellite data to produce the predicted 48-hr position of the ice edge. The NIC served as a liaison with the RDC and NRL to provide feedback on the model predictions. This evaluation provides a baseline analysis of the current models for future comparison studies

  7. The Effects of Changing Sea Ice on Marine Mammals and Their Hunters in Northern Alaska

    NASA Astrophysics Data System (ADS)

    Huntington, H.; Quakenbush, L.; Nelson, M.

    2015-12-01

    Marine mammals are important sources of food for indigenous residents of northern Alaska. Changing sea ice patterns affect the animals themselves as well as access by hunters. Documenting the traditional knowledge of Iñupiaq and Yupik hunters concerning marine mammals and sea ice makes accessible a wide range of information and insight relevant to ecological understanding, conservation action, and the regulation of human activity. We interviewed hunters in villages from northern Bering Sea to the Beaufort Sea, focusing on bowhead whales, walrus, and ice seals. Hunters reported extensive changes in sea ice, with resulting effects on the timing of marine mammal migrations, the distribution and behavior of the animals, and the efficacy of certain hunting methods, for example the difficulty of finding ice thick enough to support a bowhead whale for butchering. At the same time, hunters acknowledged impacts and potential impacts from changing technology such as more powerful outboard engines and from industrial activity such as shipping and oil and gas development. Hunters have been able to adapt to some changes, for example by hunting bowhead whales in fall as well as spring on St. Lawrence Island, or by focusing their hunt in a shorter period in Nuiqsut to accommodate work schedules and worse weather. Other changes, such as reduced availability of ice seals due to rapid retreat of pack ice after spring break-up, continue to defy easy responses. Continued environmental changes, increased disturbance from human activity, and the introduction of new regulations for hunting may further challenge the ability of hunters to provide food as they have done to date, though innovation and flexibility may also provide new sources of adaptation.

  8. Increased Arctic Sea Ice Drift Alters Polar Bear Movements and Energetics

    NASA Astrophysics Data System (ADS)

    Douglas, D. C.; Durner, G. M.; Albeke, S. E.; Whiteman, J. P.; Amstrup, S. C.; Richardson, E.; Wilson, R. R.; Ben-David, M.

    2015-12-01

    Recent thinning of Arctic sea ice has increased its drift from currents and winds. Increased ice drift could affect movements and energy balance of polar bears (Ursus maritimus) which rely, almost exclusively, on this substrate for hunting seals. Foraging by polar bears is a relatively sedentary behavior, as they typically capture their main prey by waiting at breathing holes, where seals haul-out along leads, or by short-distance stalking. We examined the response of polar bears to ice drift in the Beaufort (BS) and Chukchi (CS) seas, and between two periods with different sea ice characteristics: 1987-1998 and 1999-2013. We used satellite-tracked adult female polar bear locations, standardized by a continuous-time correlated random walk, coupled with modeled ice drift, to estimate displacement and drift-corrected bear movements along east-west and north-south axes. Sea ice drift in both regions increased with greater westward and more extreme northward and southward rates from 1987-1998 to 1999-2013. Polar bears responded with greater eastward movements and, in the CS greater movements north and south. We show that efforts by polar bears to compensate for greater westward ice drift in recent years translated into a model-derived estimate of 5.7-7.2% increase in energy expenditure. We also estimated that polar bears increased their travel time 18-20% between the two time periods, suggesting time allocated to foraging was reduced. Increased energetic costs and travel time resulting from greater ice drift, in conjunction with ongoing habitat loss, suggest that recent changes to Arctic sea ice may affect movements and energy balance of polar bears.

  9. Wintertime enhancements of sea salt aerosol in polar regions consistent with a sea ice source from blowing snow

    NASA Astrophysics Data System (ADS)

    Huang, Jiayue; Jaeglé, Lyatt

    2017-03-01

    Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface as well as by wind mobilization of saline snow and frost flowers over sea-ice-covered areas. The relative magnitude of these sources remains poorly constrained over polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation, and climate. We implement a blowing snow and a frost flower emission scheme in the GEOS-Chem global chemical transport model, which we validate against multiyear (2001-2008) in situ observations of SSA mass concentrations at three sites in the Arctic, two sites in coastal Antarctica, and from the 2008 ICEALOT cruise in the Arctic. A simulation including only open ocean emissions underestimates SSA mass concentrations by factors of 2-10 during winter-spring for all ground-based and ship-based observations. When blowing snow emissions are added, the model is able to reproduce observed wintertime SSA concentrations, with the model bias decreasing from a range of -80 to -34 % for the open ocean simulation to -2 to +9 % for the simulation with blowing snow emissions. We find that the frost flower parameterization cannot fully explain the high wintertime concentrations and displays a seasonal cycle decreasing too rapidly in early spring. Furthermore, the high day-to-day variability of observed SSA is better reproduced by the blowing snow parameterization. Over the Arctic (> 60° N) (Antarctic, > 60° S), we calculate that submicron SSA emissions from blowing snow account for 1.0 Tg yr-1 (2.5 Tg yr-1), while frost flower emissions lead to 0.21 Tg yr-1 (0.25 Tg yr-1) compared to 0.78 Tg yr-1 (1.0 Tg yr-1) from the open ocean. Blowing snow emissions are largest in regions where persistent strong winds occur over sea ice (east of Greenland, over the central Arctic, Beaufort Sea, and the Ross and Weddell seas). In contrast, frost flower emissions are largest where cold air temperatures and open leads are co-located (over the Canadian

  10. Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

    USGS Publications Warehouse

    Durner, G.M.; Whiteman, J.P.; Harlow, H.J.; Amstrup, Steven C.; Regehr, E.V.; Ben-David, M.

    2011-01-01

    Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness. ?? 2011 US Government.

  11. Influence of the sea-ice edge on the Arctic nearshore environment

    NASA Astrophysics Data System (ADS)

    Barnhart, K. R.; Overeem, I.; Anderson, R. S.

    2013-12-01

    Coasts form the dynamic interface of the terrestrial and oceanic systems. In the Arctic, and in much of the world, the coast is a zone of relatively high population, infrastructure, biodiversity, and ecosystem services. A significant difference between Arctic and temperate coasts is the presence of sea ice. Sea ice influences Arctic coasts in two main ways: (1) the length of the sea ice-free season controls the length of time over which nearshore water can interact with the land, and (2) the sea ice edge controls the fetch over which storm winds can blow over open water, resulting in changes in nearshore water level and wave field. The resulting nearshore hydrodynamic environment impacts all aspects of the coastal system. Here, we use satellite records of sea ice along with a simple model for wind-driven storm surge and waves to document how changes in the length and character of the sea ice-free season have impacted the nearshore hydrodynamic environment. For our sea ice analysis we primarily use the Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS. We make whole-Arctic maps of sea ice change in the coastal zone. In addition to evaluating changes in length of the sea ice-free season at the coast, we look at changes segmented by azimuth. This allows us to consider changes in the sea ice in the context of the wind field. For our storm surge and wave field analysis we focus on the Beaufort Sea region. This region has experienced some of the greatest changes in both sea ice cover and coastal erosion rates in the Arctic and is anticipated to experience significant change in the future. In addition, the NOAA ESRL GMD has observed the wind field at Barrow since extends to 1977. In our past work on the rapid and accelerating coastal erosion, we have shown that one may model storm surge with a 2D numerical bathystrophic model, and that waves are well represented by the Shore Protection Manual methods for shallow-water fetch-limited waves. We use

  12. EIGHTH GRADE UNIT, SEA--RESTLESS GIANT.

    ERIC Educational Resources Information Center

    CHAPMAN, FRANK L.

    AN EIGHTH GRADE UNIT GUIDE ON OCEANOLOGY HAS BEEN DEVELOPED BY THE CARTERET COUNTY PUBLIC SCHOOLS OF BEAUFORT, NORTH CAROLINA. NARRATIVE AND DIAGRAMMATIC DESCRIPTIONS DEAL WITH VARIOUS OCEAN PHENOMENA, SUCH AS TIDES, WAVES, CURRENTS, OCEAN FLOORS, BEACHES, ETC. CLASS QUESTIONS AND DISCUSSION QUESTIONS ARE PROVIDED AT THE END OF EACH SECTION OF THE…

  13. Melt ponds on Arctic sea ice determined from MODIS satellite data using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Rösel, A.; Kaleschke, L.; Birnbaum, G.

    2012-04-01

    Melt ponds on sea ice strongly reduce the surface albedo and accelerate the decay of Arctic sea ice. Due to different spectral properties of snow, ice, and water, the fractional coverage of these distinct surface types can be derived from multispectral sensors like the Moderate Resolution Image Spectroradiometer (MODIS) using a spectral unmixing algorithm. The unmixing was implemented using a multilayer perceptron to reduce computational costs. Arctic-wide melt pond fractions and sea ice concentrations are derived from the level 3 MODIS surface reflectance product. The validation of the MODIS melt pond data set was conducted with aerial photos from the MELTEX campaign 2008 in the Beaufort Sea, data sets from the National Snow and Ice Data Center (NSIDC) for 2000 and 2001 from four sites spread over the entire Arctic, and with ship observations from the trans-Arctic HOTRAX cruise in 2005. The root-mean-square errors range from 3.8 % for the comparison with HOTRAX data, over 10.7 % for the comparison with NSIDC data, to 10.3 % and 11.4 % for the comparison with MELTEX data, with coefficient of determination ranging from R2=0.28 to R2=0.45. The mean annual cycle of the melt pond fraction per grid cell for the entire Arctic shows a strong increase in June, reaching a maximum of 15 % by the end of June. The zonal mean of melt pond fractions indicates a dependence of the temporal development of melt ponds on the geographical latitude, and has its maximum in mid-July at latitudes between 80° and 88° N. Furthermore, the MODIS results are used to estimate the influence of melt ponds on retrievals of sea ice concentrations from passive microwave data. Results from a case study comparing sea ice concentrations from ARTIST Sea Ice-, NASA Team 2-, and Bootstrap-algorithms with MODIS sea ice concentrations indicate an underestimation of around 40 % for sea ice concentrations retrieved with microwave algorithms.

  14. The Impact of Sea Ice Loss on Wave Dynamics and Coastal Erosion Along the Arctic Coast

    NASA Astrophysics Data System (ADS)

    Overeem, I.; Anderson, R. S.; Wobus, C. W.; Matell, N.; Urban, F. E.; Clow, G. D.; Stanton, T. P.

    2010-12-01

    The extent of Arctic sea ice has been shrinking rapidly over the past few decades, and attendant acceleration of erosion is now occurring along the Arctic coast. This both brings coastal infrastructure into harm’s way and promotes a complex response of the adjacent landscape to global change. We quantify the effects of declining sea ice extent on coastal erosion rates along a 75-km stretch of coastal permafrost bluffs adjacent to the Beaufort Sea, Alaska, where present-day erosion rates are among the highest in the world at ~14 m yr-1. Our own observations reinforce those of others, and suggest that the rate-limiting process is thermal erosion at the base of the several-meter tall bluffs. Here we focus on the interaction between the nearshore sea ice concentration, the location of the sea ice margin, and the fetch-limited, shallow water wave field, since these parameters ultimately control both sea surface temperatures and the height to which these waters can bathe the frozen bluffs. Thirty years of daily or bi-daily passive microwave data from Nimbus-7 SMMR and DMSP SSM/I satellites reveal that the nearshore open water season lengthened ~54 days over 1979-2009. The open water season, centered in August, expands more rapidly into the fall (September and October~0.92 day yr-1) than into the early summer (July~0.71 days yr-1). Average fetch, defined for our purposes as the distance from the sea ice margin to the coast over which the wind is blowing, increased by a factor 1.7 over the same time-span. Given these time series, we modeled daily nearshore wave heights during the open water season for each year, which we integrated to provide a quantitative metric for the annual exposure of the coastal bluffs to thermal erosion. This “annual wave exposure” increased by 250% during 1979-2009. In the same interval, coastal erosion rates reconstructed from satellite and aerial photo records show less acceleration. We attribute this to a disproportionate extension of the

  15. Benefits of assimilating thin sea ice thickness from SMOS into the TOPAZ system

    NASA Astrophysics Data System (ADS)

    Xie, Jiping; Counillon, François; Bertino, Laurent; Tian-Kunze, Xiangshan; Kaleschke, Lars

    2016-11-01

    observations) near the ice edge. The areas of largest impact are the Kara Sea, Canadian Archipelago, Baffin Bay, Beaufort Sea and Greenland Sea. This study suggests that the SMOS-Ice is a good complementary data set that can be safely included in the TOPAZ system.

  16. The Cretaceous Polar and Western Interior seas: paleoenvironmental history and paleoceanographic linkages

    NASA Astrophysics Data System (ADS)

    Schröder-Adams, Claudia

    2014-03-01

    This study reviews the Cretaceous histories of the Polar and Western Interior seas as recorded in the Canadian High Arctic Sverdrup Basin, Beaufort-Mackenzie Basin of northwest Canada and Western Canadian Foreland Basin. Newly emerging stratigraphic, paleoclimatic and paleoenvironmental interpretations from the polar realm allow for a fresh look at the response of this oceanic system to global climatic trends and sea-level histories over 35 Ma. Sverdrup basin localities on Axel Heiberg and Ellef Ringnes islands represent shelf to slope environments that contrasted with the shallow water and low gradient settings of the Canadian Western Interior Sea. Both marine systems, connected throughout Aptian to Maastrichtian time, responded to global transgressive-regressive cycles resulting in dynamic paleogeographic changes. The upper Aptian to Campanian succession of the Polar Sea shows at least two unconformable boundaries; one at the Albian/Cenomanian transition and another within the upper Cenomanian. The shallow basin setting and in particular the forebulge and backbulge settings of the Western Canadian Foreland Basin are characterized by multiple erosional surfaces throughout the Cretaceous succession. The Upper Albian disconformity is widely discernible close to the entrance of the Western Interior Sea to the Polar Sea. This suggests a short-lived closure of the latest Albian Mowry Sea that might have been responsible for the large loss of benthic foraminiferal species at this time. Several oceanic anoxic events are documented in these basins representing their response to global climate dynamics. During the Late Cretaceous temperature maximum benthic foraminiferal communities were severely restricted by bottom water hypoxia in both basins. A stratified water column might have been the result of increased freshwater runoff under warm, humid conditions. These conditions supported vegetation up into the polar latitudes that added abundant organic matter to marine shelf

  17. Microwave remote sensing of sea ice in the AIDJEX Main Experiment

    USGS Publications Warehouse

    Campbell, W.J.; Wayenberg, J.; Ramseyer, J.B.; Ramseier, R.O.; Vant, M.R.; Weaver, R.; Redmond, A.; Arsenaul, L.; Gloersen, P.; Zwally, H.J.; Wilheit, T.T.; Chang, T.C.; Hall, D.; Gray, L.; Meeks, D.C.; Bryan, M.L.; Barath, F.T.; Elachi, C.; Leberl, F.; Farr, Tom

    1978-01-01

    During the AIDJEX Main Experiment, April 1975 through May 1976, a comprehensive microwave sensing program was performed on the sea ice of the Beaufort Sea. Surface and aircraft measurements were obtained during all seasons using a wide variety of active and passive microwave sensors. The surface program obtained passive microwave measurements of various ice types using four antennas mounted on a tracked vehicle. In three test regions, each with an area of approximately 1.5 ?? 104 m2, detailed ice crystallographic, dielectric properties, and brightness temperatures of first-year, multiyear, and first-year/multiyear mixtures were measured. A NASA aircraft obtained passive microwave measurements of the entire area of the AIDJEX manned station array (triangle) during each of 18 flights. This verified the earlier reported ability to distinguish first-year and multiyear ice types and concentration and gave new information on ways to observe ice mixtures and thin ice types. The active microwave measurements from aircraft included those from an X- and L-band radar and from a scatterometer. The former is used to study a wide variety of ice features and to estimate deformations, while both are equally usable to observe ice types. With the present data, only the scatterometer can be used to distinguish positively multiyear from first-year and various types of thin ice. This is best done using coupled active and passive microwave sensing. ?? 1978 D. Reidel Publishing Company.

  18. Multi-frequency, multi-polarization SAR and radiometer sea ice classification

    NASA Technical Reports Server (NTRS)

    Drinkwater, Mark R.; Crawford, John P.; Cavalieri, Donald J.

    1991-01-01

    Microwave remotely sensed data were acquired simultaneously in March 1988 over Beaufort, Chukchi, and Bering Sea ice using the JPL multifrequency, polarimetric synthetic aperture radar (SAR), and multifrequency dual-polarization GSFC radiometer. The experiment was conducted as a series of coordinated underflights of the DMSP SSM/I satellite radiometer to validate ice products derived from its radiance values. Concurrent flights by an NRL P-3 aircraft enabled overlapping high-resolution, single-frequency images to be acquired over the same surfaces using a Ka-band scanning microwave radiometer. Precise coregistration to an accuracy of 100 m, +/- 25 m enables comparison of temporally and spatially coincident active and passive microwave datasets. Three-channel polarimetric SAR data are compared with dual-polarized radiometer data at several SSM/I frequencies, showing backscatter signatures to be highly correlated with radiometric temperatures. Further comparisons are used to evaluate ice concentration retrievals and to show how multiparameter datasets can be used to resolve ambiguities present in identifying certain sea ice forms with a single microwave instrument.

  19. Sea Ice Drift in the Arctic Ocean. Seasonal Variability and Long-Term Changes

    NASA Astrophysics Data System (ADS)

    Pavlov, V.; Pavlova, O.

    2010-12-01

    Variability in the drift of sea ice in the Arctic Ocean is an important parameter that can be used to characterise the thermodynamic processes in the Arctic. Knowledge of the features of sea ice drift in the Arctic Ocean is necessary for climate research, for an improved understanding of polar ecology and as an aid to human activity in the Arctic Ocean. Monthly mean sea ice drift velocities, computed from Advanced Very High Resolution Radiometer (AVHRR), Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave/Imager (SSM/I), and International Arctic Buoy Programme (IABP) buoy data, are used to investigate the spatial and temporal variability of ice motion in the Arctic Ocean and Nordic Seas from 1979. Sea ice drift in the Arctic Ocean is characterized by strong seasonal and inter-annual variability. The results of combined statistical analysis of sea ice velocities and wind fields over the Arctic Ocean suggest that the seasonal changes of local wind are a predominant factor in the formation of the sea ice velocities annual cycle. Sea ice drift velocities mirror seasonal changes of the wind in the Arctic, reaching a maximum in December, with a minimum in June. In the central part of the Arctic Ocean and in the area near the Canadian shore the amplitude of this variation is not more than 2 cm/ sec. The maximum amplitudes are found in the Fram Strait (9-10 cm/sec), Beaufort Gyre (6-7 cm/sec) and the northern part of Barents Sea (5-6 cm/sec). Low frequency variations of sea ice drift velocities, with periods of 2.0-2.5 yrs and 5.0-6.0 yrs, are related to reorganization of the atmospheric circulation over the Arctic. There is evidence that the average sea ice velocity for the whole of the Arctic Ocean is increasing, with a positive trend for the period of last three decades. Trends of the monthly mean ice drift velocities are positive almost everywhere in the Arctic Ocean. In the Baffin Bay, Fram Strait and Barents Sea regions, sea ice velocities

  20. Aral Sea basin: a sea dies, a sea also rises.

    PubMed

    Glantz, Michael H

    2007-06-01

    The thesis of this article is quite different from many other theses of papers, books, and articles on the Aral Sea. It is meant to purposely highlight the reality of the situation in Central Asia: the Aral Sea that was once a thriving body of water is no more. That sea is dead. What does exist in its place are the Aral seas: there are in essence three bodies of water, one of which is being purposefully restored and its level is rising (the Little Aral), and two others which are still marginally connected, although they continue to decline in level (the Big Aral West and the Big Aral East). In 1960 the level of the sea was about 53 m above sea level. By 2006 the level had dropped by 23 m to 30 m above sea level. This was not a scenario generated by a computer model. It was a process of environmental degradation played out in real life in a matter of a few decades, primarily as a result of human activities. Despite wishes and words to the contrary, it will take a heroic global effort to save what remains of the Big Aral. It would also take a significant degree of sacrifice by people and governments in the region to restore the Big Aral to an acceptable level, given that the annual rate of flow reaching the Amudarya River delta is less than a 10th of what it was several decades ago. Conferring World Heritage status to the Aral Sea(s) could spark restoration efforts for the Big Aral.

  1. The Timing of Arctic Sea Ice Advance and Retreat as an Indicator of Ice-Dependent Marine Mammal Habitat

    NASA Astrophysics Data System (ADS)

    Stern, H. L.; Laidre, K. L.

    2013-12-01

    The Arctic is widely recognized as the front line of climate change. Arctic air temperature is rising at twice the global average rate, and the sea-ice cover is shrinking and thinning, with total disappearance of summer sea ice projected to occur in a matter of decades. Arctic marine mammals such as polar bears, seals, walruses, belugas, narwhals, and bowhead whales depend on the sea-ice cover as an integral part of their existence. While the downward trend in sea-ice extent in a given month is an often-used metric for quantifying physical changes in the ice cover, it is not the most relevant measure for characterizing changes in the sea-ice habitat of marine mammals. Species that depend on sea ice are behaviorally tied to the annual retreat of sea ice in the spring and advance in the fall. Changes in the timing of the spring retreat and the fall advance are more relevant to Arctic marine species than changes in the areal sea-ice coverage in a particular month of the year. Many ecologically important regions of the Arctic are essentially ice-covered in winter and ice-free in summer, and will probably remain so for a long time into the future. But the dates of sea-ice retreat in spring and advance in fall are key indicators of climate change for ice-dependent marine mammals. We use daily sea-ice concentration data derived from satellite passive microwave sensors to calculate the dates of sea-ice retreat in spring and advance in fall in 12 regions of the Arctic for each year from 1979 through 2013. The regions include the peripheral seas around the Arctic Ocean (Beaufort, Chukchi, East Siberian, Laptev, Kara, Barents), the Canadian Arctic Archipelago, and the marginal seas (Okhotsk, Bering, East Greenland, Baffin Bay, Hudson Bay). We find that in 11 of the 12 regions (all except the Bering Sea), sea ice is retreating earlier in spring and advancing later in fall. Rates of spring retreat range from -5 to -8 days/decade, and rates of fall advance range from +5 to +9

  2. 7 CFR 1437.310 - Sea grass and sea oats.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value loss... boundaries; and (3) Be managed and maintained using acceptable growing practices for the geographical...

  3. 7 CFR 1437.310 - Sea grass and sea oats.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value loss... boundaries; and (3) Be managed and maintained using acceptable growing practices for the geographical...

  4. 7 CFR 1437.310 - Sea grass and sea oats.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value loss... boundaries; and (3) Be managed and maintained using acceptable growing practices for the geographical...

  5. 7 CFR 1437.310 - Sea grass and sea oats.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value loss..., as determined by CCC. (e) The land, waterbed, or facility in which the eligible commodity was...

  6. 7 CFR 1437.310 - Sea grass and sea oats.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Sea grass and sea oats. 1437.310 Section 1437.310... Determining Coverage Using Value § 1437.310 Sea grass and sea oats. (a) Sea grass and sea oats are value loss..., as determined by CCC. (e) The land, waterbed, or facility in which the eligible commodity was...

  7. At-sea distribution of Spectacled Eiders: A 120-year-old mystery resolved

    USGS Publications Warehouse

    Petersen, Margaret R.; Larned, William W.; Douglas, D.C.

    1999-01-01

    The at-sea distribution of the threatened Spectacled Eider (Somateria fischeri) has remained largely undocumented. We identified migration corridors, staging and molting areas, and wintering areas of adult Spectacled Eiders using implanted satellite-transmitters in birds from each of the three extant breeding grounds (North Slope and Yukon-Kuskokwim Delta in Alaska and arctic Russia). Based on transmitter locations, we conducted aerial surveys to provide visual confirmation of eider flocks and to estimate numbers of birds. We identified two principal molting and staging areas off coastal Alaska (Ledyard Bay and eastern Norton Sound) and two off coastal Russia (Mechigmenskiy Bay on the eastern Chukotka Peninsula, and the area between the Indigirka and Kolyma deltas in the Republic of Sakha). We estimated that >10,000 birds molt and stage in monospecific flocks at Mechigmenskiy and Ledyard bays, and several thousand molt and stage in eastern Norton Sound. We further identified eastern Norton Sound as the principal molting and staging area for females nesting on the Yukon-Kuskokwim Delta, and Ledyard Bay and Mechigmenskiy Bay as the principal molting and staging areas for females nesting on the North Slope. Males marked at all three breeding grounds molt and stage in Mechigmenskiy Bay, Ledyard Bay, and the Indigirka-Kolyma delta region. Males from the Yukon-Kuskokwim Delta molt and stage mainly at Mechigmenskiy Bay. Equal numbers of males from the North Slope molt and stage at all three areas, and most males from arctic Russia molt and stage at the Indigirka-Kolyma delta region. Postbreeding migration corridors were offshore in the Bering, Chukchi, and Beaufort seas. In winter, eiders were in the Bering Sea south of St. Lawrence Island. Our estimates from surveys in late winter and early spring suggest that at least 333,000 birds winter in single-species flocks in the pack ice in the Bering Sea.

  8. Deep sea waste disposal

    SciTech Connect

    Kester, D.R.; Burt, W.V.; Capuzzo, J.M.; Park, P.K.; Ketchum, B.W.; Duedall, I.W.

    1985-01-01

    The book presents papers on the marine disposal of wastes. Topics considered include incineration at sea, the modelling and biological effects of industrial wastes, microbial studies of ocean dumping, deep-sea mining wastes, the chemical analysis of ferromanganese nodules, and economic aspects of deep-sea disposal.

  9. All That Unplowed Sea

    ERIC Educational Resources Information Center

    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)

  10. Quantifying the Bering Strait Oceanic Fluxes and their Impacts on Sea-Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014

    DTIC Science & Technology

    2013-09-30

    of Bering Strait flows marking the annual mean (northward) flow through the two channels of the strait ( blue arrows); the northward flowing Alaskan...current along the Russian coast [Woodgate et al., 2006]. 3 FIGURE 2: Annual means (A1-yellow; A2-cyan; A3- blue ; A4-red) of near-bottom...freshwater flux (right three panels). (Mooring locations are shown in the maps of Figure 1.) For transport and flux estimates, blue (from A3) are for the

  11. Spatial and temporal multiyear sea ice distributions in the Arctic: A neural network analysis of SSM/I data, 1988-2001

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Alpatsky, I.V.; Platonov, N.G.

    2004-01-01

    Arctic multiyear sea ice concentration maps for January 1988-2001 were generated from SSM/I brightness temperatures (19H, 19V, and 37V) using modified multiple layer perceptron neural networks. Learning data for the neural networks were extracted from ice maps derived from Okean and ERS satellite imagery to capitalize on the stability of active radar multiyear ice signatures. Evaluations of three learning algorithms and several topologies indicated that networks constructed with error back propagation learning and 3-20-1 topology produced the most consistent and physically plausible results. Operational neural networks were developed specifically with January learning data, and then used to estimate daily multiyear ice concentrations from daily-averaged SSM/I brightness temperatures during January. Monthly mean maps were produced for analysis by averaging the respective daily estimates. The 14-year series of January multiyear ice distributions revealed dense and persistent cover in the central Arctic surrounded by expansive regions of highly fluctuating interannual cover. Estimates of total multiyear ice area by the neural network were intermediate to those of other passive microwave algorithms, but annual fluctuations and trends were similar among all algorithms. When compared to Radarsat estimates of multiyear ice concentration in the Beaufort and Chukchi Seas (1997-1999), average discrepancies were small (0.9-2.5%) and spatial coherency was reasonable, indicating the neural network's Okean and ERS learning data facilitated passive microwave inversion that emulated backscatter signatures. During 1988-2001, total January multiyear ice area declined at a significant linear rate of -54.3 x 103 km2/yr-1 (-1.4%/yr-1). The most persistent and extensive decline in multiyear ice concentration (-3.3%/yr-1) occurred in the southern Beaufort and Chukchi Seas. In autumn 1996, a large multiyear ice recruitment of over 106 km2 (mostly in the Siberian Arctic) fully replenished

  12. The Caspian Sea Environment

    NASA Astrophysics Data System (ADS)

    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.

  13. Dust Storm, Aral Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Aral Sea has shrunk to less than half its size since 1985. The Aral Sea receives little water (sometimes no water) from the two major rivers that empty into it-the Syr Darya and Amu Darya. Instead, the river water is diverted to support irrigation for the region's extensive cotton fields. Recently, water scarcity has increased due to a prolonged drought in Central Asia. As the Aral Sea recedes, its former sea bed is exposed. The Aral's sea bed is composed of fine sediments-including fertilizers and other agricultural chemicals-that are easily picked up by the region's strong winds, creating thick dust storms. The International Space Station crew observed and recorded a large dust storm blowing eastward from the Aral Sea in late June 2001. This image illustrates the strong coupling between human activities (water diversions and irrigation), and rapidly changing land, sea and atmospheric processes-the winds blow across the

  14. 77 FR 11492 - Notice of Availability of a Draft Environmental Assessment for the Issuance of Incidental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-27

    ... incidental to offshore oil and gas exploratory drilling programs in the U.S. Beaufort and Chukchi Seas... offshore exploratory drilling programs in the U.S. Beaufort and Chukchi Seas. NMFS published Notices of... Conducting Exploratory Drilling Programs in the U.S. Beaufort and Chukchi Seas.'' Publication of this...

  15. Observing Arctic Sea Ice from Bow to Screen: Introducing Ice Watch, the Data Network of Near Real-Time and Historic Observations from the Arctic Shipborne Sea Ice Standardization Tool (ASSIST)

    NASA Astrophysics Data System (ADS)

    Orlich, A.; Hutchings, J. K.; Green, T. M.

    2013-12-01

    The Ice Watch Program is an open source forum to access in situ Arctic sea ice conditions. It provides the research community and additional stakeholders a convenient resource to monitor sea ice and its role in understanding the Arctic as a system by implementing a standardized observation protocol and hosting a multi-service data portal. International vessels use the Arctic Shipborne Sea Ice Standardization Tool (ASSIST) software to report near-real time sea ice conditions while underway. Essential observations of total ice concentration, distribution of multi-year ice and other ice types, as well as their respective stage of melt are reported. These current and historic sea ice conditions are visualized on interactive maps and in a variety of statistical analyses, and with all data sets available to download for further investigation. The summer of 2012 was the debut of the ASSIST software and the Ice Watch campaign, with research vessels from six nations reporting from a wide spatio-temporal scale spanning from the Beaufort Sea, across the North Pole and Arctic Basin, the coast of Greenland and into the Kara and Barents Seas during mid-season melt and into the first stages of freeze-up. The 2013 summer field season sustained the observation and data archiving record, with participation from some of the same cruises as well as other geographic and seasonal realms covered by new users. These results are presented to illustrate the evolution of the program, increased participation and critical statistics of ice regime change and record of melt and freeze processes revealed by the data. As an ongoing effort, Ice Watch/ASSIST aims to standardize observations of Arctic-specific sea ice features and conditions while utilizing nomenclature and coding based on the World Meteorological Organization (WMO) standards and the Antarctic Sea Ice and Processes & Climate (ASPeCt) protocol. Instigated by members of the CliC Sea Ice Working Group, the program has evolved with

  16. Is ice-rafted sediment in a North Pole marine record evidence for perennial sea-ice cover?

    PubMed

    Tremblay, L B; Schmidt, G A; Pfirman, S; Newton, R; DeRepentigny, P

    2015-10-13