WorldWideScience

Sample records for temperate polar sea

  1. Indirect effects of sea otter recovery on temperate reef fish

    OpenAIRE

    Silberg, Joshua Neal

    2015-01-01

    The loss or recovery of apex predators can have profound positive or negative ecological and socio-economic impacts. Effects of predator depletion or recovery are frequently accompanied by time lags, which are often context-dependent. In temperate rocky reef ecosystems, sea otters (Enhydra lutris) trigger a cascade of direct and indirect effects driving transitions between kelp-depleted and kelp-dominated states. We quantified the indirect effects of sea otter recovery on copper rockfish (Seb...

  2. Seasonal iron depletion in temperate shelf seas

    Science.gov (United States)

    Birchill, Antony J.; Milne, Angela; Woodward, E. Malcolm S.; Harris, Carolyn; Annett, Amber; Rusiecka, Dagmara; Achterberg, Eric P.; Gledhill, Martha; Ussher, Simon J.; Worsfold, Paul J.; Geibert, Walter; Lohan, Maeve C.

    2017-09-01

    Our study followed the seasonal cycling of soluble (SFe), colloidal (CFe), dissolved (DFe), total dissolvable (TDFe), labile particulate (LPFe), and total particulate (TPFe) iron in the Celtic Sea (NE Atlantic Ocean). Preferential uptake of SFe occurred during the spring bloom, preceding the removal of CFe. Uptake and export of Fe during the spring bloom, coupled with a reduction in vertical exchange, led to Fe deplete surface waters (supply from remineralized sinking organic material, and cycled independently of particulate Fe over seasonal timescales. These results demonstrate that summer Fe availability is comparable to the seasonally Fe limited Ross Sea shelf and therefore is likely low enough to affect phytoplankton growth and species composition.

  3. Toxicity of natural mixtures of organic pollutants in temperate and polar marine phytoplankton

    KAUST Repository

    Echeveste, Pedro

    2016-07-26

    Semivolatile and persistent organic pollutants (POPs) undergo atmospheric transport before being deposited to the oceans, where they partition to phytoplankton organic matter. The goal of this study was to determine the toxicity of naturally occurring complex mixtures of organic pollutants to temperate and polar phytoplankton communities from the Mediterranean Sea, the North East (NE) Atlantic, and Southern Oceans. The cell abundance of the different phytoplankton groups, chlorophyll a concentrations, viability of the cells, and growth and decay constants were monitored in response to addition of a range of concentrations of mixtures of organic pollutants obtained from seawater extracts. Almost all of the phytoplankton groups were significantly affected by the complex mixtures of non-polar and polar organic pollutants, with toxicity being greater for these mixtures than for single POPs or simple POP mixtures. Cocktails\\' toxicity arose at concentrations as low as tenfold the field oceanic levels, probably due to a higher chemical activity of the mixture than of simple POPs mixtures. Overall, smaller cells were the most affected, although Mediterranean picophytoplankton was significantly more tolerant to non-polar POPs than picophytoplankton from the Atlantic Ocean or the Bellingshausen Sea microphytoplankton. © 2016 Elsevier B.V.

  4. Psychrophilic versus psychrotolerant bacteria--occurrence and significance in polar and temperate marine habitats.

    Science.gov (United States)

    Helmke, E; Weyland, H

    2004-07-01

    The numerical dominance and ecological role of psychrophilic bacteria in bottom sediments, sea ice, surface water and melt pools of the polar oceans were investigated using isolates, colony forming units (CFU) and metabolic activities. All sediment samples of the Southern Ocean studied showed a clear numerical dominance of cold-loving bacteria. In Arctic sediments underlying the influence of cold polar water bodies psychrophiles prevailed also but they were less dominant in sediments influenced by the warm Atlantic Water. A predominance of psychrophiles was further found in consolidated Antarctic sea ice as well as in multiyear Arctic sea ice and in melt pools on top of Arctic ice floes. A less uniform adaptation response was, however, met in polar surface waters. In the very northern part of the Fram Strait (Arctic Ocean) we found bacterial counts and activities at 1 degree C exceeding those at 22 degrees C. In surface water of the Weddell Sea (Southern Ocean) psychrophiles also dominated numerically in early autumn but the dominance declined obviously with the onset of winter-water and a decrease of chlorphyll a. Otherwise in surface water of the Southern Ocean CFUs were higher at 22 degrees C than at 1 degree C while activities were vice versa indicating at least a functional dominance of psychrophiles. Even in the temperate sediments of the German Bight true psychrophiles were present and a clear shift towards cold adapted communities in winter observed. Among the polar bacteria a more pronounced cold adaptation of Antarctic in comparison with Arctic isolates was obtained. The results and literature data indicate that stenothermic cold adapted bacteria play a significant role in the global marine environment. On the basis of the temperature response of our isolates from different habitats it is suggested to expand the definition of Morita in order to meet the cold adaptation strategies of the bacteria in the various cold habitats.

  5. Polar bears and sea ice habitat change

    Science.gov (United States)

    Durner, George M.; Atwood, Todd C.; Butterworth, Andy

    2017-01-01

    The polar bear (Ursus maritimus) is an obligate apex predator of Arctic sea ice and as such can be affected by climate warming-induced changes in the extent and composition of pack ice and its impacts on their seal prey. Sea ice declines have negatively impacted some polar bear subpopulations through reduced energy input because of loss of hunting habitats, higher energy costs due to greater ice drift, ice fracturing and open water, and ultimately greater challenges to recruit young. Projections made from the output of global climate models suggest that polar bears in peripheral Arctic and sub-Arctic seas will be reduced in numbers or become extirpated by the end of the twenty-first century if the rate of climate warming continues on its present trajectory. The same projections also suggest that polar bears may persist in the high-latitude Arctic where heavy multiyear sea ice that has been typical in that region is being replaced by thinner annual ice. Underlying physical and biological oceanography provides clues as to why polar bear in some regions are negatively impacted, while bears in other regions have shown no apparent changes. However, continued declines in sea ice will eventually challenge the survival of polar bears and efforts to conserve them in all regions of the Arctic.

  6. SeaWinds - Oceans, Land, Polar Regions

    Science.gov (United States)

    1999-01-01

    The SeaWinds scatterometer on the QuikScat satellite makes global radar measurements -- day and night, in clear sky and through clouds. The radar data over the oceans provide scientists and weather forecasters with information on surface wind speed and direction. Scientists also use the radar measurements directly to learn about changes in vegetation and ice extent over land and polar regions.This false-color image is based entirely on SeaWinds measurements obtained over oceans, land, and polar regions. Over the ocean, colors indicate wind speed with orange as the fastest wind speeds and blue as the slowest. White streamlines indicate the wind direction. The ocean winds in this image were measured by SeaWinds on September 20, 1999. The large storm in the Atlantic off the coast of Florida is Hurricane Gert. Tropical storm Harvey is evident as a high wind region in the Gulf of Mexico, while farther west in the Pacific is tropical storm Hilary. An extensive storm is also present in the South Atlantic Ocean near Antarctica.The land image was made from four days of SeaWinds data with the aid of a resolution enhancement algorithm developed by Dr. David Long at Brigham Young University. The lightest green areas correspond to the highest radar backscatter. Note the bright Amazon and Congo rainforests compared to the dark Sahara desert. The Amazon River is visible as a dark line running horizontally though the bright South American rain forest. Cities appear as bright spots on the images, especially in the U.S. and Europe.The image of Greenland and the north polar ice cap was generated from data acquired by SeaWinds on a single day. In the polar region portion of the image, white corresponds to the largest radar return, while purple is the lowest. The variations in color in Greenland and the polar ice cap reveal information about the ice and snow conditions present.NASA's Earth Science Enterprise is a long-term research and technology program designed to examine Earth

  7. Carbon dioxide uptake by a temperate tidal sea

    NARCIS (Netherlands)

    Klaassen, Wim

    2007-01-01

    Carbon dioxide (CO2) exchange between the atmosphere and the Wadden Sea, a shallow coastal region along the northern Netherlands, has been measured from April 2006 onwards on a tidal flat and over open water. Tidal flat measurements were done using a flux chamber, and ship borne measurements using

  8. East Greenland and Barents Sea polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Pertoldi, Cino; Sonne, Christian; Wiig, Øystein

    2012-01-01

    A morphometric study was conducted on four skull traits of 37 male and 18 female adult East Greenland polar bears (Ursus maritimus) collected 18921968, and on 54 male and 44 female adult Barents Sea polar bears collected 19501969. The aim was to compare differences in size and shape of the bear...... and three clusters for Barents Sea females. East Greenland consisted of one female and one male cluster. A principal component analysis (PCA) conducted on the clusters defined by the mixture analysis, showed that East Greenland and Barents Sea polar bear populations overlapped to a large degree, especially...... and genetic factors seem to have contributed to the observed skull differences between the two populations. Overall, results indicate that many Barents Sea polar bears are morphometrically similar to the East Greenland ones, suggesting an exchange of individuals between the two populations. Furthermore...

  9. Nimbus-7 SMMR Polar Gridded Radiances and Sea Ice Concentrations

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains gridded brightness temperatures and sea ice concentrations for both polar regions. It spans the period from October 1978 through August 1987,...

  10. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Directory of Open Access Journals (Sweden)

    Karyn D Rode

    Full Text Available Recent observations suggest that polar bears (Ursus maritimus are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013 when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia, highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  11. Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions

    Science.gov (United States)

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  12. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Science.gov (United States)

    Rode, Karyn D; Wilson, Ryan R; Regehr, Eric V; St Martin, Michelle; Douglas, David C; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  13. Polar Sea Ice Monitoring Using HY-2A Scatterometer Measurements

    Directory of Open Access Journals (Sweden)

    Mingming Li

    2016-08-01

    Full Text Available A sea ice detection algorithm based on Fisher’s linear discriminant analysis is developed to segment sea ice and open water for the Ku-band scatterometer onboard the China’s Hai Yang 2A Satellite (HY-2A/SCAT. Residual classification errors are reduced through image erosion/dilation techniques and sea ice growth/retreat constraint methods. The arctic sea-ice-type classification is estimated via a time-dependent threshold derived from the annual backscatter trends based on previous HY-2A/SCAT derived sea ice extent. The extent and edge of the sea ice obtained in this study is compared with the Special Sensor Microwave Imager/Sounder (SSMIS sea ice concentration data and the Sentinel-1 SAR imagery for verification, respectively. Meanwhile, the classified sea ice type is compared with a multi-sensor sea ice type product based on data from the Advanced Scatterometer (ASCAT and SSMIS. Results show that HY-2A/SCAT is powerful in providing sea ice extent and type information, while differences in the sensitivities of active/passive products are found. In addition, HY-2A/SCAT derived sea ice products are also proved to be valuable complements for existing polar sea ice data products.

  14. Sea-ice indicators of polar bear habitat

    Directory of Open Access Journals (Sweden)

    H. L. Stern

    2016-09-01

    Full Text Available Nineteen subpopulations of polar bears (Ursus maritimus are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat on its way to the summer minimum or rises above the threshold (advance on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014 mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade−1 in spring and from +3 to +9 days decade−1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade−1, with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade−1. These sea-ice metrics (or indicators of habitat change were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in

  15. Sea-ice indicators of polar bear habitat

    Science.gov (United States)

    Stern, Harry L.; Laidre, Kristin L.

    2016-09-01

    Nineteen subpopulations of polar bears (Ursus maritimus) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology - the cycle of biological events - is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979-2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from -3 to -9 days decade-1 in spring and from +3 to +9 days decade-1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of -7 to -19 days decade-1, with larger trends in the Barents Sea and central Arctic Basin. The June-October sea-ice concentration is declining in all regions at rates ranging from -1 to -9 percent decade-1. These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports.

  16. Growth and photosynthesis of Chlorella strains from polar, temperate and tropical freshwater environments under temperature stress

    Science.gov (United States)

    Lee, Kok-Keong; Lim, Phaik-Eem; Poong, Sze-Wan; Wong, Chiew-Yen; Phang, Siew-Moi; Beardall, John

    2017-09-01

    Elevated temperatures as a consequence of global warming have significant impacts on the adaptation and survival of microalgae which are important primary producers in many ecosystems. The impact of temperature on the photosynthesis of microalgae is of great interest as the primary production of algal biomass is strongly dependent on the photosynthetic rates in a dynamic environment. Here, we examine the effects of elevated temperature on Chlorella strains originating from different latitudes, namely Antarctic, Arctic, temperate and tropical regions. Chlorophyll fluorescence was used to assess the photosynthetic responses of the microalgae. Rapid light curves (RLCs) and maximum quantum yield (F v/F m) were recorded. The results showed that Chlorella originating from different latitudes portrayed different growth trends and photosynthetic performance. The Chlorella genus is eurythermal, with a broad temperature tolerance range, but with strain-specific characteristics. However, there was a large overlap between the tolerance range of the four strains due to their "eurythermal adaptivity". Changes in the photosynthetic parameters indicated temperature stress. The ability of the four strains to reactivate photosynthesis after inhibition of photosynthesis under high temperatures was also studied. The Chlorella strains were shown to recover in terms of photosynthesis and growth (measured as Chl a) when they were returned to their ambient temperatures. Polar strains showed faster recovery in their optimal temperature compared to that under the ambient temperature from which they were isolated.

  17. Polar Lows Over the Northeast Greenland Sea

    Science.gov (United States)

    1991-12-01

    Danmarks Havn in North East Greenland near 77 N. However, as pointed out by Rasmussen L (1989) the climate in this region is extremely cold, and katabatic...Satellite images. Satel ite images from 16th Novembe~r 1987 when the polar low was best developed show such a "katabatic signiature’ .1 the Danmarks

  18. DMSP SSM/I Daily and Monthly Polar Gridded Bootstrap Sea Ice Concentrations

    Data.gov (United States)

    National Aeronautics and Space Administration — DMSP SSM/I Daily and Monthly Polar Gridded Bootstrap Sea Ice Concentrations in polar stereographic projection currently include Defense Meteorological Satellite...

  19. Ross Sea oceanographic data, 1983-1987 : USCGC Glacier, January-February 1983; USCGC Polar Sea, January-February 1984; USCGC Polar Star, February 1985; USCGC Polar Sea, February 1987 (NODC Accession 8900108)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and chemical data were collected using CTD casts from USCGC POLAR SEA and other platforms in the Ross Sea from 19 December 1976 to 06 February...

  20. Limits to diffusive O2 transport: flow, form, and function in nudibranch egg masses from temperate and polar regions.

    Directory of Open Access Journals (Sweden)

    Amy L Moran

    Full Text Available BACKGROUND: Many aquatic animals enclose embryos in gelatinous masses, and these embryos rely on diffusion to supply oxygen. Mass structure plays an important role in limiting or facilitating O2 supply, but external factors such as temperature and photosynthesis can play important roles as well. Other external factors are less well understood. METHODOLOGY/PRINCIPAL FINDINGS: We first explored the effects of water flow on O2 levels inside nudibranch embryo masses and compared the effects of flow on masses from temperate and polar regions. Water flow (still vs. vigorously bubbled had a strong effect on central O2 levels in all masses; in still water, masses were considerably more hypoxic than in bubbled water. This effect was stronger in temperate than in polar masses, likely due to the increased metabolic demand and O2 consumption of temperate masses. Second, we made what are to our knowledge the first measurements of O2 in invertebrate masses in the field. Consistent with laboratory experiments, O2 in Antarctic masses was high in masses in situ, suggesting that boundary-layer effects do not substantially limit O2 supply to polar embryos in the field. CONCLUSIONS/SIGNIFICANCE: All else being equal, boundary layers are more likely to depress O2 in masses in temperate or tropical regions; thus, selection on parents to choose high-flow sites for mass deposition is likely greater in warm water. Because of the large number of variables affecting diffusive O2 supply to embryos in their natural environment, field observations are necessary to test hypotheses generated from laboratory experiments and mathematical modeling.

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

    Science.gov (United States)

    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

  2. Biomagnification of persistent organic pollutants in a deep-sea, temperate food web.

    Science.gov (United States)

    Romero-Romero, Sonia; Herrero, Laura; Fernández, Mario; Gómara, Belén; Acuña, José Luis

    2017-12-15

    Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were measured in a temperate, deep-sea ecosystem, the Avilés submarine Canyon (AC; Cantabrian Sea, Southern Bay of Biscay). There was an increase of contaminant concentration with the trophic level of the organisms, as calculated from stable nitrogen isotope data (δ15N). Such biomagnification was only significant for the pelagic food web and its magnitude was highly dependent on the type of top predators included in the analysis. The trophic magnification factor (TMF) for PCB-153 in the pelagic food web (spanning four trophic levels) was 6.2 or 2.2, depending on whether homeotherm top predators (cetaceans and seabirds) were included or not in the analysis, respectively. Since body size is significantly correlated with δ15N, it can be used as a proxy to estimate trophic magnification, what can potentially lead to a simple and convenient method to calculate the TMF. In spite of their lower biomagnification, deep-sea fishes showed higher concentrations than their shallower counterparts, although those differences were not significant. In summary, the AC fauna exhibits contaminant levels comparable or lower than those reported in other systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Impacts of Tropopause Polar Cyclones on Arctic Sea Ice Loss

    Science.gov (United States)

    Szapiro, N.; Cavallo, S. M.; Skamarock, W. C.; Park, S. H.

    2016-12-01

    Arctic sea ice exhibits considerable and potentially abrupt year to year variability, with changes amplified as the ice thins. Extremes of summer Arctic sea ice loss are intimately connected to the atmospheric forcing. On sub-seasonal to seasonal time scales, there are significant correlations between upper level heights, sea level pressure, and sea ice loss. Individual synoptic cyclones can also drive significant ice loss.Cyclonic tropopause polar vortices (TPVs) are common, coherent upper level potential vorticity anomalies with typical radii of 100 to 1000 km and lifetimes of days to months. Here, we test the hypothesis that TPVs have significant impacts on the evolution and predictability of summer sea ice loss.Historical TPV-based composites reveal coherent mass, momentum, and energy sea ice forcings under TPVs, with implications for pack ice maintenance and marginal ice loss. Coupled MPAS-CESM sensitivity experiments with strengthened and weakened TPVs quantify the sea ice response to these forcings at both short- and extended-range time scales. The coupling of forcings between TPVs and larger scales is seen to contribute to the significance of impacts. Since modelling systems exhibit systematic errors in the representation of TPVs, resolving these errors may realize the potential predictability associated with TPVs.

  4. The use of sea ice habitat by female polar bears in the Beaufort Sea

    Science.gov (United States)

    Durner, George M.; Amstrup, Steven C.; Nielson, Ryan M.; McDonald, Trent

    2003-01-01

    Polar bears (Ursus maritimus) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We used stepwise procedures to create resource selection models of habitat use for radio-collared female polar bears in the Beaufort Sea. Sea ice characteristics and ocean depths at known polar bear locations were compared to the same features at randomly selected locations. Models generated for each of four seasons confirmed complexities of habitat use by polar bears and their response to numerous factors. Bears preferred shallow water areas where ice concentrations were > 80 % and different ice types intersected. Variation among seasons was reflected mainly in differential selection of ice stages, floe sizes, and their interactions. Water depth, total ice concentration and distance to the nearest interface between different ice types were significant terms in models for most seasons. Variation in ice stage and form also appeared in three models, and several interaction effects were identified. Habitat selection by polar bears is likely related to prey abundance and availability. Use of habitats in shallow water possibly reflects higher productivity in those areas. Habitat use in close proximity to ice edges is probably related to greater access of prey in those habitats.

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

    Science.gov (United States)

    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.

  6. Occurrence of the Chilean devil ray Mobula tarapacana (Elasmobranchii: Batoidea: Myliobatiformes) in the Sea of Okhotsk: first record from cold temperate waters.

    Science.gov (United States)

    Tomita, T; Kawai, T; Matsubara, H; Nagata, R

    2013-09-01

    The northernmost record for Chilean devil ray Mobula tarapacana, a circumglobal species that occurs in tropical, subtropical and limited warm temperate waters, is described. An adult female was caught incidentally in the Sea of Okhotsk on 17 September 2011. This specimen is the first confirmed occurrence of devil rays Mobula spp. in cold temperate waters. © 2013 The Fisheries Society of the British Isles.

  7. Information on weather and sea conditions onboard polar cruise ships

    Directory of Open Access Journals (Sweden)

    BRÂNDUŞA CHIOTOROIU

    2016-11-01

    Full Text Available The arctic and Antarctic regions are difficult to navigate because of their severe maritime conditions. Weather forecast, forecast of the sea ice and icebergs dynamics are extremely important when planning ships routes and tourism activities including embarkation/disembarkation from boats or landing operations. New meteorological services have been created in the arctic region for broadcast purposes. The information provided by these services and received onboard ships is presented in this paper. A risk assessment should be considered for Polar Water operations such as maneuvering in ice covered waters, anchoring, shore landings etc.

  8. Comparison of whole animal costs of protein synthesis among polar and temperate populations of the same species of gammarid amphipod.

    Science.gov (United States)

    Rastrick, S P S; Whiteley, N M

    2017-05-01

    Protein synthesis can account for a substantial proportion of metabolic rate. Energetic costs of protein synthesis, should in theory, be the same in marine invertebrates from a range of thermal habitats, and yet direct measurements using inhibitors produce widely differing values, especially in the cold. The present study aimed to remove any potential confounding interspecific effects by determining costs of protein synthesis in two latitudinally separated populations of the same species (amphipod, Gammarus oceanicus) living in two different thermal regimes; polar vs cold-temperate. Costs of protein synthesis were determined in summer acclimatised G. oceanicus from Svalbard (79°N) at 5°C and from Scotland (58°N) at 13°C. Amphipods were injected with the protein synthesis inhibitor, cycloheximide (CHX), at 9mmoll-1 in crab saline to give a tissue concentration of 0.05mgCHXg-1FW and left for 60min before the injection of [3H] phenylalanine. After incubation for 120min (180min in total from initial injection), both whole-animal rates of oxygen uptake and absolute rates of protein synthesis were significantly reduced in CHX-treated amphipods vs controls injected with saline. Both populations exhibited similar costs of protein synthesis of ~7μmolO2mg-1protein which is close to the estimated theoretical minimum for peptide bond formation, and similar to the values obtained in cell-free systems. The study demonstrates that in G. oceanicus, costs of protein synthesis rates were not elevated in the cold but were fixed among polar and cold-temperate populations. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. On the importance for climate science communication - the climate office for polar regions and sea level rise

    Science.gov (United States)

    Treffeisen, Renate; Lemke, Peter; Dethloff, Klaus

    2010-05-01

    Climate change presents a major challenge for national and international action and cooperation. A wide variation in the vulnerability is to be expected across different regions, due to regional differences in local environmental conditions, preexisting stresses to ecosystems, current resource-use patterns, and the framework of factors affecting decision-making including government policies, prices, preferences, and values. Thus, considerable regional impact differences will be faced as a result of climate change. Being aware will help to prepare for these inevitable consequences in time. Climate change is nowhere more strongly expressed than in the polar regions which respond to even small changes in climate. Given the major role played by these regions within the Earth's climate system the climate office for polar regions and sea level rise is hosted by the Foundation Alfred Wegener Institute for Polar and Marine Research (AWI) which conducts research in the Arctic, the Antarctic and at temperate latitudes since 1980. The major goal of the climate office is to encourage the communication and dialogue between science and public. Primarily, this is done by the unique close contact and cooperation to the research center scientists. A continuous exchange is supported beyond the research center towards universities and authorities at state and federal level. The climate office represents polar aspects of climate related research based on the scientific expertise from the hosting research institute e.g. the understanding of the ocean-ice-atmosphere interactions, the animal and plant kingdoms of the Arctic and Antarctic, and the evolution of the polar continents and seas. The climate office translates the scientific work into English, making complex issues accessible to policymakers and the public. It compiles, evaluates, comprehensively process and transparently communicate the latest findings from polar related climate research. The paper will present different

  10. Polar bear and walrus response to the rapid decline in Arctic sea ice

    Science.gov (United States)

    Oakley, K.; Whalen, M.; Douglas, D.; Udevitz, M.; Atwood, T.; Jay, C.

    2012-01-01

    The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus rosmarus divergens) are dependent on sea ice over the continental shelves of the Arctic Ocean's marginal seas. The continental shelves are shallow regions with high biological productivity, supporting abundant marine life within the water column and on the sea floor. Polar bears use sea ice as a platform for hunting ice seals; walruses use sea ice as a resting platform between dives to forage for clams and other bottom-dwelling invertebrates. How have sea ice changes affected polar bears and walruses? How will anticipated changes affect them in the future?

  11. Weakening of the Stratospheric Polar Vortex by Arctic Sea-Ice Loss

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

    2014-09-02

    Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea ice, the mechanism that links sea ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhance the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January- February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

  12. Significance of the Autumn Bloom within the Seasonal Cycle of Primary Production in a Temperate Continental Shelf Sea

    Science.gov (United States)

    Wihsgott, Juliane U.; Sharples, Jonathan; Hopkins, Joanne; Woodward, Malcolm; Greenwood, Naomi; Sivyer, Dave; Hull, Tom

    2017-04-01

    Autumnal phytoplankton blooms are considered characteristic features of the seasonal cycle of primary productivity in most temperate and subpolar oceans. While observations of their occurrence and strength have been documented extensively, their significance within the seasonal cycle of primary production is not well quantified. Our aim is to establish the role the autumn bloom plays within the seasonal cycle and estimate its contribution to the annual primary production of a temperate continental shelf. In particular, we will illustrate that the autumn bloom has the potential to be as productive as the well-studied summer sub-surface chlorophyll maximum (SCM) and the capacity to significantly contribute to the drawdown of atmospheric CO2. We do this by combining long-term, high resolution observations of water column structure, meteorological forcing, nitrate and chlorophyll fluorescence over the entire seasonal cycle observed in a temperate shelf sea. We present a new series of continuous measurements spanning 17 months (March 2014 - July 2015), which were collected in a temperate shelf sea on the North West European Shelf. A long-term mooring array recorded full depth vertical density structure, dynamics and meteorological data as well as surface chlorophyll fluorescence biomass and inorganic nutrient data over a full seasonal cycle at a station 120 km north-east from the continental shelf break. Eight process cruises supplied additional full depth profiles of chlorophyll fluorescence biomass and macronutrients. The breakdown of stratification in 2014 commenced in early October due to increased winds compared to summer months, and a predominantly negative net heat flux (the ocean lost heat to the overlying atmosphere). Vertical mixing in autumn not only transformed the vertical density structure but also the vertical structure of chlorophyll biomass and surface nutrients. The SCM became eroded and instead a vertically homogeneous profile of chlorophyll biomass

  13. Baltic Sea Experiment (BALTEX) Ground-Based Radar Polar Volume Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes non-Doppler polar volume reflectivity data from the Baltic Sea Experiment (BALTEX). Data were collected on Sweden's Gotland Island, using an...

  14. Baltic Sea Experiment (BALTEX) Ground-Based Radar Polar Volume Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes non-Doppler polar volume reflectivity data from the Baltic Sea Experiment (BALTEX). Data were collected on Sweden's Gotland Island, using an...

  15. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines

    Science.gov (United States)

    Laidre, K. L.; Regehr, E. V.; Akcakaya, H. R.; Amstrup, S. C.; Atwood, T.; Lunn, N.; Obbard, M.; Stern, H. L., III; Thiemann, G.; Wiig, O.

    2016-12-01

    Loss of Arctic sea ice due to climate change is the most serious threat to polar bears (Ursus maritimus) throughout their circumpolar range. We performed a data-based sensitivity analysis with respect to this threat by evaluating the potential response of the global polar bear population to projected sea-ice conditions. We conducted 1) an assessment of generation length for polar bears, 2) developed of a standardized sea-ice metric representing important habitat characteristics for the species; and 3) performed population projections over three generations, using computer simulation and statistical models representing alternative relationships between sea ice and polar bear abundance. Using three separate approaches, the median percent change in mean global population size for polar bears between 2015 and 2050 ranged from -4% (95% CI = -62%, 50%) to -43% (95% CI = -76%, -20%). Results highlight the potential for large reductions in the global population if sea-ice loss continues. They also highlight the large amount of uncertainty in statistical projections of polar bear abundance and the sensitivity of projections to plausible alternative assumptions. The median probability of a reduction in the mean global population size of polar bears greater than 30% over three generations was approximately 0.71 (range 0.20-0.95. The median probability of a reduction greater than 50% was approximately 0.07 (range 0-0.35), and the probability of a reduction greater than 80% was negligible.

  16. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence.

    Science.gov (United States)

    Amstrup, Steven C; Deweaver, Eric T; Douglas, David C; Marcot, Bruce G; Durner, George M; Bitz, Cecilia M; Bailey, David A

    2010-12-16

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

  17. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

    Science.gov (United States)

    Amstrup, Steven C.; Deweaver, E.T.; Douglas, D.C.; Marcot, B.G.; Durner, G.M.; Bitz, C.M.; Bailey, D.A.

    2010-01-01

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the worlds polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

  18. Invariant polar bear habitat selection during a period of sea ice loss.

    Science.gov (United States)

    Wilson, Ryan R; Regehr, Eric V; Rode, Karyn D; St Martin, Michelle

    2016-08-17

    Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar bear habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar bears as sea ice loss continues. Our results indicate that bears are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar bears. © 2016 The Author(s).

  19. Polar Sea Ice Monitoring Using HY-2A Scatterometer Measurements

    OpenAIRE

    Mingming Li; Chaofang Zhao; Yong Zhao; Zhixiong Wang; Lijian Shi

    2016-01-01

    A sea ice detection algorithm based on Fisher’s linear discriminant analysis is developed to segment sea ice and open water for the Ku-band scatterometer onboard the China’s Hai Yang 2A Satellite (HY-2A/SCAT). Residual classification errors are reduced through image erosion/dilation techniques and sea ice growth/retreat constraint methods. The arctic sea-ice-type classification is estimated via a time-dependent threshold derived from the annual backscatter trends based on previous HY-2A/SCAT ...

  20. Polar Bear Conservation Status in Relation to Projected Sea-ice Conditions

    Science.gov (United States)

    Regehr, E. V.

    2015-12-01

    The status of the world's 19 subpopulations of polar bears (Ursus maritimus) varies as a function of sea-ice conditions, ecology, management, and other factors. Previous methods to project the response of polar bears to loss of Arctic sea ice—the primary threat to the species—include expert opinion surveys, Bayesian Networks providing qualitative stressor assessments, and subpopulations-specific demographic analyses. Here, we evaluated the global conservation status of polar bears using a data-based sensitivity analysis. First, we estimated generation length for subpopulations with available data (n=11). Second, we developed standardized sea-ice metrics representing habitat availability. Third, we projected global population size under alternative assumptions for relationships between sea ice and subpopulation abundance. Estimated generation length (median = 11.4 years; 95%CI = 9.8 to 13.6) and sea-ice change (median = loss of 1.26 ice-covered days per year; 95%CI = 0.70 to 3.37) varied across subpopulations. Assuming a one-to-one proportional relationship between sea ice and abundance, the median percent change in global population size over three polar bear generations was -30% (95%CI = -35% to -25%). Assuming a linear relationship between sea ice and normalized estimates of subpopulation abundance, median percent change was -4% (95% CI = -62% to +50%) or -43% (95% CI = -76% to -20%), depending on how subpopulations were grouped and how inference was extended from relatively well-studied subpopulations (n=7) to those with little or no data. Our findings suggest the potential for large reductions in polar bear numbers over the next three polar bear generations if sea-ice loss due to climate change continues as forecasted.

  1. Future for polar bears in a declining sea ice environment: What do we know?

    Science.gov (United States)

    Amstrup, Steven C.

    2006-01-01

    During an April 22, 2006, interview on the CBC radio program “The House,” Tim Flannery, author of the recent book “The Weathermakers,” stated, “Projections of the polar bear specialists are that by about 2030, around that date, the species will be extinct because of global warming induced changes in the Arctic sea ice.” That statement was followed on May 4th by quotations in the Toronto Globe and Mail from Dr. Mitch Taylor, a polar bear researcher in Nunavut, Canada, claiming, “polar bears have survived both warmer times and colder times than these,” that “nothing has melted the Arctic sea ice for 30 million years,” that “polar bears are remarkably adaptable,” and that “a warming climate might even benefit polar bears.”

  2. Airborne geophysics for mesoscale observations of polar sea ice in a changing climate

    Science.gov (United States)

    Hendricks, S.; Haas, C.; Krumpen, T.; Eicken, H.; Mahoney, A. R.

    2016-12-01

    Sea ice thickness is an important geophysical parameter with a significant impact on various processes of the polar energy balance. It is classified as Essential Climate Variable (ECV), however the direct observations of the large ice-covered oceans are limited due to the harsh environmental conditions and logistical constraints. Sea-ice thickness retrieval by the means of satellite remote sensing is an active field of research, but current observational capabilities are not able to capture the small scale variability of sea ice thickness and its evolution in the presence of surface melt. We present an airborne observation system based on a towed electromagnetic induction sensor that delivers long range measurements of sea ice thickness for a wide range of sea ice conditions. The purpose-built sensor equipment can be utilized from helicopters and polar research aircraft in multi-role science missions. While airborne EM induction sounding is used in sea ice research for decades, the future challenge is the development of unmanned aerial vehicle (UAV) platform that meet the requirements for low-level EM sea ice surveys in terms of range and altitude of operations. The use of UAV's could enable repeated sea ice surveys during the the polar night, when manned operations are too dangerous and the observational data base is presently very sparse.

  3. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue

    Science.gov (United States)

    Galicia, Melissa P.; Thiemann, Gregory W.; Belt, Simon T.; Yurkowski, David J.; Dyck, Markus G.

    2018-01-01

    Polar bears (Ursus maritimus) rely upon Arctic sea ice as a physical habitat. Consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. However, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. Here we used the highly branched isoprenoid lipid biomarker-based index (H-Print) approach in combination with quantitative fatty acid signature analysis to show that sympagic (sea ice-associated), rather than pelagic, carbon contributions dominated the marine component of polar bear diet (72–100%; 99% CI, n = 55), irrespective of differences in diet composition. The lowest mean estimates of sympagic carbon were found in Baffin Bay bears, which were also exposed to the most rapidly increasing open water season. Therefore, our data illustrate that for future Arctic ecosystems that are likely to be characterised by reduced sea ice cover, polar bears will not only be impacted by a change in their physical habitat, but also potentially in the supply of energy to the ecosystems upon which they depend. This data represents the first quantifiable baseline that is critical for the assessment of likely ongoing changes in energy supply to Arctic predators as we move into an increasingly uncertain future for polar ecosystems. PMID:29360849

  4. Increased Arctic Sea Ice Drift Alters Polar Bear Movements and Energetics

    Science.gov (United States)

    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.

  5. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

    Science.gov (United States)

    Hamilton, Stephen G; Castro de la Guardia, Laura; Derocher, Andrew E; Sahanatien, Vicki; Tremblay, Bruno; Huard, David

    2014-01-01

    Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 - 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands. Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

  6. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

    Directory of Open Access Journals (Sweden)

    Stephen G Hamilton

    Full Text Available Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 - 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling.Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands.Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

  7. Annual Reproductive Cycle and Unusual Embryogenesis of a Temperate Coral in the Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Chiara Marchini

    Full Text Available The variety of reproductive processes and modes among coral species reflects their extraordinary regeneration ability. Scleractinians are an established example of clonal animals that can exhibit a mixed strategy of sexual and asexual reproduction to maintain their populations. This study provides the first description of the annual reproductive cycle and embryogenesis of the temperate species Caryophyllia inornata. Cytometric analyses were used to define the annual development of germ cells and embryogenesis. The species was gonochoric with three times more male polyps than female. Polyps were sexually mature from 6 to 8 mm length. Not only females, but also sexually inactive individuals (without germ cells and males were found to brood their embryos. Spermaries required 12 months to reach maturity, while oogenesis seemed to occur more rapidly (5-6 months. Female polyps were found only during spring and summer. Furthermore, the rate of gamete development in both females and males increased significantly from March to May and fertilization was estimated to occur from April to July, when mature germ cells disappeared. Gametogenesis showed a strong seasonal influence, while embryos were found throughout the year in males and in sexually inactive individuals without a defined trend. This unusual embryogenesis suggests the possibility of agamic reproduction, which combined with sexual reproduction results in high fertility. This mechanism is uncommon and only four other scleractinians (Pocillopora damicornis, Tubastraea diaphana, T. coccinea and Oulastrea crispata have been shown to generate their broods asexually. The precise nature of this process is still unknown.

  8. Rainfall as a trigger for stratification and winter phytoplankton growth in temperate shelf seas

    Science.gov (United States)

    Jardine, Jenny; Palmer, Matthew; Mahaffey, Claire; Holt, Jason; Mellor, Adam; Wakelin, Sarah

    2017-04-01

    We present new data from ocean gliders to investigate physical controls on stratification and phytoplankton dynamics, collected in the Celtic Sea between November 2014 and August 2015 as part of the UK Shelf Sea Biogeochemistry programme. This presentation focuses on the winter period (Jan-March) when the diurnal heating cycle results in regular but weak near surface stratification followed by night-time convection. Despite low light conditions, this daily cycle often promotes a daytime increase in observed chlorophyll fluorescence, indicative of phytoplankton growth. This daily cycle is occasionally interrupted when buoyancy inputs are sufficient to outcompete night-time convection and result in short-term periods of sustained winter stratification, typically lasting 2-3 days. Sustained stratification often coincides with periods of heavy rainfall, suggesting freshwater input from precipitation may play a role on these events by producing a subtle yet significant freshening of the surface layer of the order of 0.005 PSU. Comparing rainfall estimates with observed salinity changes confirms rainfall to often be the initiator of these winter stratification periods. As winter winds subside and solar heating increases towards spring, the water column becomes more susceptible to periods of halo-stratification, such that heavy rainfall during the winter-spring transition is likely to promote sustained stratification. The timing and extent of a heavy rainfall event in March 2015 does suggest it may be the critical trigger for shelf-wide stratification that eventually instigates the spring bloom. We propose that the timing of these downpours relative to the daily heating cycle can be a triggering mechanism for both short term and seasonal stratification in shelf seas, and so play a critical role in winter and early spring phytoplankton growth and the shelf sea carbon cycle. We further test the importance of this process using historical data, and results from the NEMO-AMM7

  9. Movement of a female polar bear (Ursus maritimus) in the Kara Sea during the summer sea-ice break-up.

    Science.gov (United States)

    Rozhnov, V V; Platonov, N G; Naidenko, S V; Mordvintsev, I N; Ivanov, E A

    2017-01-01

    The polar bear movement trajectory in relation to onset date of the sea-ice break-up was studied in the coastal zone of the Taimyr Peninsula, eastern part of the Kara Sea, using as an example a female polar bear tagged by a radio collar with an Argos satellite transmitter. Analysis of the long-term pattern of ice melting and tracking, by means of satellite telemetry, of the female polar bear who followed the ice-edge outgoing in the north-eastern direction (in summer 2012) suggests that direction of the polar bear movement depends precisely on the direction of the sea-ice cover break-up.

  10. Reduced body size and cub recruitment in polar bears associated with sea ice decline

    Science.gov (United States)

    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.

  11. Reduced body size and cub recruitment in polar bears associated with sea ice decline.

    Science.gov (United States)

    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.

  12. Seasonality in the cross-shelf physical structure in a temperate shelf sea

    Science.gov (United States)

    Ruiz-Castillo, Eugenio

    2017-04-01

    The Celtic Sea represents a transition zone between saline open ocean Atlantic water and fresher waters of the Bristol Channel. The convergence, circulation and exchange of these waters are key to understanding the nutrient cycling on the shelf. The mean annual contribution of salinity to density is thought to be relatively small, however seasonality in fresh riverine input helps to modify horizontal density gradients that drive shelf-wide circulation patterns and important cross-shelf transports. Here we describe the seasonal influence of the fresher coastal waters and heat input on the hydrography of the Celtic Sea. CTD data from 9 oceanographic cruises, obtained in the period between March 2014 and August 2015, were used in the analysis. In the early part of the year (winter), when the rate of surface heating is low and the riverine discharge is a maximum, the salinity differences are important in determining the density structure. The haline horizontal gradient is strengthened in winter by the input of fresher water from the Bristol Channel. In spring the atmospheric heat input generates an homogeneous warm layer in the upper 30 m which allows to remove the temperature gradient terms in the horizontal pressure gradient force. Therefore the pressure gradient force, which depends on the salinity gradient, is balanced by the frictional terms in the vertical. This leads to opposite flows in the bottom and surface layers. Analogous to estuarine circulation, fresher waters appear to be transported offshore in the surface layer and relatively high salinity waters are transported onshore in the deeper water. The displacements of the salinity contours indicate upper offshore and bottom onshore flows of 1 km/day. In the upper layer, an onshore flow with high salinity waters occurs when the horizontal pressure gradient is weakened following the low outflow from the Bristol Channel. In winter, enhanced winds and heat loss mix the water column. Through these mechanisms the

  13. Polarization Techniques for Mitigation of Low Grazing Angle Sea Clutter

    Science.gov (United States)

    2017-01-01

    feedback 43 as well as recording-control input. See Table 3.1 for a summary of system specifications as configured for the experiment. Photos of the system...surroundings (Haykin, 1990; Haykin, 2006). Haykin has erected one corner of his vast body of work upon the study of radar sea clutter, a fair portion of

  14. The Barents Sea polar front and water masses variability (1980-2011)

    Science.gov (United States)

    Oziel, L.; Sirven, J.; Gascard, J.-C.

    2015-03-01

    The polar front separates the warm and saline Atlantic Waters encountered in the western part of the Barents Sea from the cold and fresh Arctic Waters situated in the northern part. These water masses can mix together, mainly in the eastern part of the Barents Sea, generating dense waters in winter which can cascade into the Arctic Ocean to form the Artic Intermediate Waters. To study the interannual variability and evolution of these water masses and the fronts, we have merged data from the International Council for the Exploration of the Sea and the Arctic and Antarctic Research Institute and have built a new database which covers the period 1980-2011. The summer data is interpolated on a regular grid and a "Probability Density Function" method is used to show that the polar front splits into two branches east of 32° E where the topographic constraint weakens. Two fronts can then be defined: the "Northern Polar Front" is associated with strong salinity gradients and the "Southern Polar Front" with temperature gradients. They enclose the dense Barents Sea Water. The interannual variability of the water masses is apparent in the observed data and is linked to that of the ice cover. In contrast, the link with the Arctic Oscillation is not clear. However, results from a general circulation model suggest that such a link could be found if winter data were taken into account. A strong trend, which amplifies during the last decade, is also found: the Atlantic Water occupies a larger volume of the Barents Sea. This "Atlantification" could be accompanied by a northwards displacement of the southern polar front in the eastern part of the Barents Sea (which is suggested by a model based study) and a decrease of the volume occupied by the Arctic Waters.

  15. Contact-independent polarization of the cell surface and cortex of free sea urchin blastomeres.

    Science.gov (United States)

    Schroeder, T E

    1988-02-01

    In a normal, intact sea urchin embryo blastomeres are structurally polarized so that all microvilli and cortical "pigment granules" are situated at the apical surfaces facing the hyaline layer and are absent from basolateral surfaces facing adjacent blastomeres and the internal embryonic cavity. To test the roles of intercellular contacts and the hyaline layer in the process of establishing this blastomere polarity, these two factors were experimentally eliminated; sea urchin eggs of four species were denuded of the nascent hyaline layer soon after fertilization and then cultured in calcium-free artificial seawater to prevent subsequent intercellular adhesion and contact. Such free blastomeres divided normally and still developed polarized distributions of microvilli and pigment granules resembling those of the corresponding blastomeres in intact embryos. These results indicate that the process of polarization is intrinsic to individual blastomeres (self-polarization) and that neither intercellular contacts nor adhesion of microvilli to the hyaline layer is necessary. The precise temporal and spatial coincidence of the patterns of polarization and the division cycles further suggests that a mechanistic link is maintained among cell division, blastomere polarization, and probably also a heritable component of the animal-vegetal axis.

  16. Barents Sea polar bears (Ursus maritimus: population biology and anthropogenic threats

    Directory of Open Access Journals (Sweden)

    Magnus Andersen

    2016-07-01

    Full Text Available This paper examines how anthropogenic threats, such as disturbance, pollution and climate change, are linked to polar bear (Ursus maritimus population biology in the Svalbard and Barents Sea area, with the aim to increase our understanding of how human activity may impact the population. Overharvesting drastically reduced the population of polar bears in the Barents Sea region from about 1870 to 1970. After harvesting was stopped—in 1956 in Russia and 1973 in Norway—the population grew to an estimated 2650 individuals (95% confidence interval 1900–3600 in 2004, and maternity denning in the Svalbard Archipelago became more widely distributed. During recent decades, the population has faced challenges from a variety of new anthropogenic impacts: a range of pollutants, an increasing level of human presence and activity as well as changes in ice conditions. Contaminants bioaccumulate up through the marine food web, culminating in this top predator that consumes ringed, bearded and harp seals. Females with small cubs use land-fast sea ice for hunting and are therefore vulnerable to disturbance by snowmobile drivers. Sea-ice diminution, associated with climate change, reduces polar bears’ access to denning areas and could negatively affect the survival of cubs. There are clear linkages between population biology and current anthropogenic threats, and we suggest that future research and management should focus on and take into consideration the combined effects of several stressors on polar bears.

  17. Fermi wave vector for the partially spin-polarized composite-fermion Fermi sea

    DEFF Research Database (Denmark)

    Coimbatore Balram, Ajit; Jain, Jainendra

    2017-01-01

    The fully spin polarized composite fermion (CF) Fermi sea at half filled lowest Landau level has a Fermi wave vector $k^*_{\\rm F}=\\sqrt{4\\pi\\rho_e}$, where $\\rho_e$ is the density of electrons or composite fermions, supporting the notion that the interaction between composite fermions can...... CFFSs at $\

  18. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

    Science.gov (United States)

    Steven C. Amstrup; Eric T. DeWeaver; David C. Douglas; Bruce G. Marcot; George M. Durner; Cecilia M. Bitz; David A. Bailey

    2010-01-01

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible...

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

    Science.gov (United States)

    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.

  20. Increased Arctic sea ice drift alters adult female polar bear movements and energetics

    Science.gov (United States)

    Durner, George M.; Douglas, David C.; Albeke, Shannon; Whiteman, John P.; Amstrup, Steven C.; Richardson, Evan; Wilson, Ryan R.; Ben-David, Merav

    2017-01-01

    Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987–1998 and 1999–2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%–9.6%) or by increasing their travel speed (8.5%–8.9%). This increased their calculated annual energy expenditure by 1.8%–3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1–3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic.

  1. Increased Arctic sea ice drift alters adult female polar bear movements and energetics.

    Science.gov (United States)

    Durner, George M; Douglas, David C; Albeke, Shannon E; Whiteman, John P; Amstrup, Steven C; Richardson, Evan; Wilson, Ryan R; Ben-David, Merav

    2017-09-01

    Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  2. On classification of sea surface oil films using TerraSAR-X satellite polarization data

    Science.gov (United States)

    Ivonin, D. V.; Ivanov, A. Yu.

    2017-09-01

    The paper presents the results of applying a new polarization method proposed in [28] to identify the type of surface pollution and differentiate between mineral oil films (crude oil and its emulsion and petroleum products) and films of other origin in sea surface radar images. The method is based on calculation of the quantitative characteristics for the ratios of suppression or intensification of scattered radio signals of different physical nature, viz., caused by capillary ripples several centimeters long, or wave breaking. TerraSAR-X satellite coaxial-polarized (VV/HH) SAR images are used. The data for analysis have been collected in areas where spots and slicks of known origin regularly occur, such as oil spills and natural oil seeps in the Gulf of Mexico and the Caspian Sea, and biogenic films in the Caspian Sea. The results of analyzing radar images from the TerraSAR-X satellite with controlled experimental oil emulsion spills in the North Sea are used for comparison. Based on the analysis of ten TerraSAR-X radar polarization images with surface sensing angles greater than 30°, it is shown that this method makes it possible to distinguish between oil spills and slicks formed by natural oil seeps and biogenic films with an accuracy higher than 80% regardless of the observation area.

  3. An unsuccessful attempt to elicit orientation responses to linearly polarized light in hatchling loggerhead sea turtles (Caretta caretta)

    Science.gov (United States)

    Mäthger, Lydia M.; Lohmann, Kenneth J.; Limpus, Colin J.; Fritsches, Kerstin A.

    2011-01-01

    Sea turtles undertake long migrations in the open ocean, during which they rely at least partly on magnetic cues for navigation. In principle, sensitivity to polarized light might be an additional sensory capability that aids navigation. Furthermore, polarization sensitivity has been linked to ultraviolet (UV) light perception which is present in sea turtles. Here, we tested the ability of hatchling loggerheads (Caretta caretta) to maintain a swimming direction in the presence of broad-spectrum polarized light. At the start of each trial, hatchling turtles, with their magnetic sense temporarily impaired by magnets, successfully established a steady course towards a light-emitting diode (LED) light source while the polarized light field was present. When the LED was removed, however, hatchlings failed to maintain a steady swimming direction, even though the polarized light field remained. Our results have failed to provide evidence for polarized light perception in young sea turtles and suggest that alternative cues guide the initial migration offshore. PMID:21282179

  4. Potential impacts of offshore oil spills on polar bears in the Chukchi Sea.

    Science.gov (United States)

    Wilson, Ryan R; Perham, Craig; French-McCay, Deborah P; Balouskus, Richard

    2018-01-12

    Sea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1-10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27-38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans. Published by Elsevier Ltd.

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

    Science.gov (United States)

    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 (polar bear population in the northern Beaufort Sea will eventually decline. Management and conservation practices for polar bears in relation to both aboriginal harvesting and offshore industrial activity will need to

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

    Science.gov (United States)

    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 (climate continues to warm as predicted, we predict that the polar bear population in the northern Beaufort Sea will eventually decline. Management and conservation practices for polar bears in relation to both

  7. Summer Activity Sensor Data from Collars Deployed on Female Polar Bears in the Chukchi Sea 1989 to 1995 and Southern Beaufort Sea 1989 to 2014

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These are data collected from two types of activity sensors housed within collars deployed on female polar bears in the Chukchi and southern Beaufort Seas during the...

  8. Age and sex composition of seals killed by polar bears in the eastern Beaufort Sea.

    Directory of Open Access Journals (Sweden)

    Nicholas W Pilfold

    Full Text Available BACKGROUND: Polar bears (Ursus maritimus of the Beaufort Sea enter hyperphagia in spring and gain fat reserves to survive periods of low prey availability. We collected information on seals killed by polar bears (n=650 and hunting attempts on ringed seal (Pusa hispida lairs (n=1396 observed from a helicopter during polar bear mark-recapture studies in the eastern Beaufort Sea in spring in 1985-2011. We investigated how temporal shifts in ringed seal reproduction affect kill composition and the intraspecific vulnerabilities of ringed seals to polar bear predation. PRINCIPAL FINDINGS: Polar bears primarily preyed on ringed seals (90.2% while bearded seals (Erignathus barbatus only comprised 9.8% of the kills, but 33% of the biomass. Adults comprised 43.6% (150/344 of the ringed seals killed, while their pups comprised 38.4% (132/344. Juvenile ringed seals were killed at the lowest proportion, comprising 18.0% (62/344 of the ringed seal kills. The proportion of ringed seal pups was highest between 2007-2011, in association with high ringed seal productivity. Half of the adult ringed seal kills were ≥ 21 years (60/121, and kill rates of adults increased following the peak of parturition. Determination of sex from DNA revealed that polar bears killed adult male and adult female ringed seals equally (0.50, n=78. The number of hunting attempts at ringed seal subnivean lair sites was positively correlated with the number of pup kills (r(2 =0.30, P=0.04, but was not correlated with the number of adult kills (P=0.37. CONCLUSIONS/SIGNIFICANCE: Results are consistent with decadal trends in ringed seal productivity, with low numbers of pups killed by polar bears in spring in years of low pup productivity, and conversely when pup productivity was high. Vulnerability of adult ringed seals to predation increased in relation to reproductive activities and age, but not gender.

  9. A Polarized Drell-Yan Experiment to Probe the Dynamics of the Nucleon Sea

    Energy Technology Data Exchange (ETDEWEB)

    Kleinjan, David William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-26

    After presenting the nucleon spin puzzle as motivation for the experiment, the authors turn to a theoretical overview: sea quark flavor asymmetry and meson cloud model, and accessing quark angular momentum via the Sivers function. Then they describe the experimental equipment and conditions needed to carry out a fixed, polarized target Drell-Yan experiment, E1039. Data taking is expected to start in the middle of 2016.

  10. A Polarization Technique for Mitigating Low Grazing Angle Radar Sea Clutter

    Science.gov (United States)

    2017-03-03

    be incorporated into the standard radar signal processing chain in parallel with the usual Doppler processing and 2-D CFAR operations , and as shown...A Polarization Technique for Mitigating Low-Grazing-Angle Radar Sea Clutter Molly K. Crane MIT Lincoln Laboratory Lexington, MA 02420 Email...MA 02420 Email: mabel.ramirez@ll.mit.edu Abstract—Traditional detection schemes in conventional mar- itime surveillance radars may suffer serious

  11. Invariant polar bear habitat selection during a period of sea ice loss

    OpenAIRE

    Wilson, Ryan R.; Regehr, Eric V.; Rode, Karyn D.; St Martin, Michelle

    2016-01-01

    Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey ...

  12. Formation of reactive species and induction of antioxidant defence systems in polar and temperate marine invertebrates and fish.

    Science.gov (United States)

    Abele, Doris; Puntarulo, Susana

    2004-08-01

    High oxygen solubility at cold-water temperature is frequently considered to be responsible for an apparently elevated level of antioxidant protection in marine ectotherms from polar environments. However, tissue oxidative stress is in most cases a function of elevated or variable pO2, rather than of an elevated tissue oxygen concentration. This review summarizes current knowledge on pro- and antioxidant processes in marine invertebrates and fish, and relates reactive oxygen species (ROS) formation in polar ectotherms to homeoviscous adaptations of membrane and storage lipids, as well as to tissue hypoxia and re-oxygenation during physiological stress.

  13. Sea Ice Detection with Sentinel-1A Dual Polarization SAR Data

    Science.gov (United States)

    Zhang, Yi; Zhang, Ming; Ji, Yonggang

    2016-08-01

    Sentinel-1A satellite was launched in the 3rd of April 2014. It is the first mission of the Copernicus family of Sentinels is designed to provide continuous routine data for the operational monitoring of oceans and land, and to support coordinated and rapid response operations to disasters (e.g. landslides and floods) as well as humanitarian aid missions. In this paper an approach to sea ice detection with dual polarization Sentinel-1A SAR data was presented. Firstly, the backscatter coefficients and texture features are achieved, in this step we found the best set of parameters including the window size, orientation, displacement and quantization levels, and the most useful texture characteristics to be used for detection, the effective GLCM texture features are mean and variance in HH polarization as well as mean, variance and correlation in HV polarization. In the end, the SVM classification was carried out with a series of bands, which including the texture characteristics and the backscatter information as the inputs. The final result shows good between sea ice and open water discrimination, which is important to the sea ice monitoring.

  14. Sensor and Location data from Ear Tag PTTs Deployed on Polar Bears in the Southern Beaufort Sea 2009 to 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These are data collected from Wildlife Computers ear tag platform transmitter terminals (PTT) deployed on polar bears in the southern Beaufort Sea during the months...

  15. An unsuccessful attempt to elicit orientation responses to linearly polarized light in hatchling loggerhead sea turtles (Caretta caretta)

    OpenAIRE

    Mäthger, Lydia M; Lohmann, Kenneth J.; Limpus, Colin J.; Fritsches, Kerstin A.

    2011-01-01

    Sea turtles undertake long migrations in the open ocean, during which they rely at least partly on magnetic cues for navigation. In principle, sensitivity to polarized light might be an additional sensory capability that aids navigation. Furthermore, polarization sensitivity has been linked to ultraviolet (UV) light perception which is present in sea turtles. Here, we tested the ability of hatchling loggerheads (Caretta caretta) to maintain a swimming direction in the presence of broad-spectr...

  16. Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair.

    Science.gov (United States)

    Wong, Chiew-Yen; Teoh, Ming-Li; Phang, Siew-Moi; Lim, Phaik-Eem; Beardall, John

    2015-01-01

    , suggesting negative effects of global climate change on microalgae inhabiting (circum-) polar regions. For temperate and tropical strains of Chlorella, damage from UVR was independent of temperature but the repair constant increased with increasing temperature, implying an improved ability of these strains to recover from UVR stress under global warming.

  17. Patterns of parasite transmission in polar seas: Daily rhythms of cercarial emergence from intertidal snails

    Science.gov (United States)

    Prokofiev, Vladimir V.; Galaktionov, Kirill V.; Levakin, Ivan A.

    2016-07-01

    Trematodes are common parasites in intertidal ecosystems. Cercariae, their dispersive larvae, ensure transmission of infection from the first intermediate molluscan host to the second intermediate (invertebrates and fishes) or the final (fishes, marine birds and mammals) host. Trematode transmission in polar seas, while interesting in many respects, is poorly studied. This study aimed to elucidate the patterns of cercarial emergence from intertidal snails at the White Sea and Barents Sea. The study, involving cercariae of 12 species, has provided the most extensive material obtained so far in high latitude seas (66-69° N). The experiments were conducted in situ. Multichannel singular spectral analysis (MSSA) used for processing primary data made it possible to estimate the relative contribution of different oscillations into the analysed time series and to separate the daily component from the other oscillatory components and the noise. Cercarial emergence had pronounced daily rhythms, which did not depend on the daily tidal schedule but were regulated by thermo- and photoperiod. Daily emergence maximums coincided with periods favourable for infecting the second intermediate hosts. Cercarial daily emergence rhythms differed in species using the same molluscan hosts which can be explained by cercarial host searching behaviour. Daily cercarial output (DCO) correlated negatively with larval volume and positively with that of the molluscan host except in cercariae using ambuscade behaviour. In the Barents Sea cercariae emerged from their molluscan hosts at lower temperatures than in the warmer White Sea but the daily emergence period was prolonged. Thus, DCO of related species were similar in these two seas and comparable with DCO values reported for boreal seas. Local temperature adaptations in cercarial emergence suggests that in case of Arctic climate warming trematode transmission in coastal ecosystems is likely to be intensified not because of the increased

  18. What About Sea Ice? People, animals, and climate change in the polar regions: An online resource for the International Polar Year and beyond

    Science.gov (United States)

    Renfrow, S.; Meier, W. N.; Wolfe, J.; Scott, D.; Leon, A.; Weaver, R.

    2005-12-01

    Decreasing Arctic sea ice has been one of the most noticeable changes on Earth over the past quarter-century. The years 2002 through 2005 have had much lower summer sea ice extents than the long-term (1979-2000). Reduced sea ice extent has a direct impact on Arctic wildlife and people, as well as ramifications for regional and global climate. Students, educators, and the general public want and need to have a better understanding of sea ice. Most of us are unfamiliar with sea ice: what it is, where it occurs, and how it affects global climate. The upcoming International Polar Year will provide an opportunity for the public to learn about sea ice. Here, we provide an overview of sea ice, the changes that the sea ice is undergoing, and information about the relation between sea ice and climate. The information presented here is condensed from the National Snow and Ice Data Center's new 'All About Sea Ice' Web site (http://www.nsidc.org/seaice/), a comprehensive resource of information for sea ice.

  19. Temporal complexity of southern Beaufort Sea polar bear diets during a period of increasing land use

    Science.gov (United States)

    McKinney, Melissa A.; Atwood, Todd C.; Iverson, Sara J.; Peacock, Elizabeth

    2017-01-01

    From 2000 to 2013, use of land as a seasonal habitat by polar bears (Ursus maritimus) of the southern Beaufort Sea (SB) subpopulation substantially increased. This onshore use has been linked to reduced spatial and temporal availability of sea ice, as well as to the availability of subsistence-harvested bowhead whale (Balaena mysticetus) bone piles. Here, we evaluated the role of climate conditions on consumption of traditional ice-associated prey relative to onshore bowhead whale bone piles. We determined seasonal and interannual trends in the diets of SB polar bears using fatty acid-based analysis during this period of increasing land use. Diet estimates of 569 SB polar bears from 2004 to 2012 showed high seasonal fluctuations in the proportions of prey consumed. Higher proportions of bowhead whale, as well as ringed seal (Pusa hispida) and beluga whale (Delphinapterus leucas), were estimated to occur in the winter–spring diet, while higher proportions of bearded seal (Erignathus barbatus) were estimated for summer–fall diets. Trends in the annual mean proportions of individual prey items were not found in either period, except for significant declines in the proportion of beluga in spring-sampled bears. Nonetheless, in years following a high winter Arctic oscillation index, proportions of ice-associated ringed seal were lower in the winter–spring diets of adult females and juveniles. Proportions of bowhead increased in the winter–spring diets of adult males with the number of ice-free days over the continental shelf. In one or both seasons, polar bears that were in better condition were estimated to have consumed less ringed seal and/or more bowhead whale than those in worse condition. Therefore, climate variation over this recent period appeared to influence the extent of onshore vs. on-ice food use, which in turn, appeared to be linked to fluctuating condition of SB polar bears.

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

    Science.gov (United States)

    Kirk, Cassandra M.; Amstrup, Steven C.; 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.

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

    Science.gov (United States)

    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.

  2. Diving In To Sea Level Rise Using The Polar Explorer ';App'

    Science.gov (United States)

    Turrin, M.; Ryan, W. B.; Bell, R. E.; Pfirman, S. L.; Bell, B.; Porter, D. F.

    2013-12-01

    The vast majority of our lifetime is spent learning outside the classroom, yet the major emphasis in developing climate change instructional materials has been the traditional K16 school environment. The Polar Learning and Responding (PoLAR) project of the National Science Foundation supported Climate Change Education Partnership (CCEP) program chose to move beyond the classroom to focus on lifelong learners, in order to engage the adult population in building public understanding about climate change. Yet reaching individuals who make their own decisions about what and how they choose to learn requires a very different approach to developing educational materials. With an adult audience how we deliver content can be as critical as what we deliver. Using materials and platforms that are readily available and familiar to the user is important. With a significant segment of our time spent connected to smart phones and tablets, employing these platforms to deliver content makes sense. Whether at work, home or in transit, portable devices are critical companions and trusted tools in providing information on everything from the latest news to the daily weather. The world of Apps is equally as familiar to the adult user, so developing an engaging climate App for a portable device offers a successful strategy. The 'Polar Explorer - Sea Level Rise (SLR) App', is one of the new interactive products developed as part of the PoLAR project. Modeled after Columbia's Earth Observer App, a data exploration and data visualization tool, the Polar Explorer SLR App includes a wide range of real Earth data from ocean and atmospheric temperatures to depth of ice layers, underlying topography and human impacts. The Polar Explorer SLR App is grounded in the concept that scientists gain insights into climate change and climate processes through directly examining data. With some scaffolding, the public can gain similar insights using the same data. Structured to be 'question driven' the

  3. Annual and interannual variability of the Barents Sea water masses and polar front: 1980-2011

    Science.gov (United States)

    Oziel, Laurent; Sirven, Jerome; Gascard, Jean-Claude

    2015-04-01

    The Barents Sea (BS) is a transition area between the warm and saline Atlantic Waters (AW) and the cold and fresh Arctic Waters (ArW). The BS is characterized by a polar front structure separating AW from ArW. The mixing and cooling of these two water mass generates dense waters in winter. Dense waters are of prior importance because they cascade into the Arctic Ocean to form the Artic Intermediate Waters. This study will use a new hydrographic data set fulfilled by recent stations in the Russian area and a 3D model coupled with atmosphere and ice as a back up to investigate the link between fronts and water masses, as well as their variability over the last 30 years. This study suggests that the polar front structure is composed of two branches and that the dense waters are found in between. The BS, especially in the East, is experiencing an "Atlantification" accompanied with a drastic sea ice decline. These changes, amplified during the last decade, shift the southern branch of the polar front structure in the Norh-East direction and affect negatively the dense water formation. This could have major impacts on the Arctic Ocean ventilation and primary production.

  4. Recovery of coastal ecosystems after large tsunamis in various climatic zones - review of cases from tropical, temperate and polar zones (Invited)

    Science.gov (United States)

    Szczucinski, W.

    2013-12-01

    Large tsunamis cause significant changes in coastal ecosystems. They include modifications in shoreline position, sediment erosion and deposition, new initial soil formation, salination of soils and waters, removal of vegetation, as well as direct impact on humans and infrastructure. The processes and rate of coastal zone recovery from large tsunamis has been little studied but during the last decade a noteworthy progress has been made. This study focus on comparison of recovery processes in various climatic zones, namely in monsoonal-tropical, temperate and polar zone. It is based on own observation and monitoring in areas affected by 2004 Indian Ocean Tsunami in Thailand, 2011 Tohoku-oki tsunami in Japan and 2000 Paatuut landslide-generated tsunami in Vaigat Strait (west Greenland), as well as on review of published studies from those areas. The particular focus is on physical and biological recoveries of beaches, recovery of coastal vegetation, new soil formation in eroded areas and those covered by tsunami deposits, marine salt removal from soils, surface- and groundwater, as well as landscape adjustment after the tsunamis. The beach zone - typically the most tsunami-eroded zone, has been recovered already within weeks to months and has been observed to be in the pre-tsunami equilibrium stage within one year in all the climate zones, except for sediment-starved environments. The existing data on beach ecosystems point also to relatively fast recovery of meio- and macrofauna (within weeks to several months). The recovery of coastal vegetation depends on the rate of salt removal from soils or on the rate of soil formation in case of its erosion or burial by tsunami deposits. The salt removal have been observed to depend mainly on precipitation and effective water drainage. In tropical climate with seasonal rainfall of more 3000 mm the salt removal was fast, however, in temperate climate with lower precipitation and flat topography the salinities still exceeded

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

    Science.gov (United States)

    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.

  6. Filling the Polar Data Gap in Sea Ice Concentration Fields Using Partial Differential Equations

    Directory of Open Access Journals (Sweden)

    Courtenay Strong

    2016-05-01

    Full Text Available The “polar data gap” is a region around the North Pole where satellite orbit inclination and instrument swath for SMMR and SSM/I-SSMIS satellites preclude retrieval of sea ice concentrations. Data providers make the irregularly shaped data gap round by centering a circular “pole hole mask” over the North Pole. The area within the pole hole mask has conventionally been assumed to be ice-covered for the purpose of sea ice extent calculations, but recent conditions around the perimeter of the mask indicate that this assumption may already be invalid. Here we propose an objective, partial differential equation based model for estimating sea ice concentrations within the area of the pole hole mask. In particular, the sea ice concentration field is assumed to satisfy Laplace’s equation with boundary conditions determined by observed sea ice concentrations on the perimeter of the gap region. This type of idealization in the concentration field has already proved to be quite useful in establishing an objective method for measuring the “width” of the marginal ice zone—a highly irregular, annular-shaped region of the ice pack that interacts with the ocean, and typically surrounds the inner core of most densely packed sea ice. Realistic spatial heterogeneity in the idealized concentration field is achieved by adding a spatially autocorrelated stochastic field with temporally varying standard deviation derived from the variability of observations around the mask. To test the model, we examined composite annual cycles of observation-model agreement for three circular regions adjacent to the pole hole mask. The composite annual cycle of observation-model correlation ranged from approximately 0.6 to 0.7, and sea ice concentration mean absolute deviations were of order 10 − 2 or smaller. The model thus provides a computationally simple approach to solving the increasingly important problem of how to fill the polar data gap. Moreover, this

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

    Science.gov (United States)

    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.

  8. QCD analysis of flavor-asymmetry for polarized sea quark distributions

    Energy Technology Data Exchange (ETDEWEB)

    Mirjalili, A. [Physics Department, Yazd University, Yazd, Iran and Institute for Studies in Theoretical Physics and Mathematics, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: Mirjalili@ipm.ir; Khorramian, Ali N. [Physics Department, Semnan University, Semnan, Iran and Institute for Studies in Theoretical Physics and Mathematics, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: Alinaghi.Khorramian@cern.ch; Atashbar Tehrani, S. [Physics Department, Persian Gulf University, Boushehr, Iran and Institute for Studies in Theoretical Physics and Mathematics, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: Atashbar@ipm.ir

    2007-02-15

    We analyze flavor-asymmetry in the light-quark sea distribution, using polarized valon framework. The comparison of our obtained results for {delta}u-bar (x,Q{sup 2}), {delta}d-bar (x,Q{sup 2}) and {delta}s-bar (x,Q{sup 2}) with the GRSV model and recent experimental data from HERMES group indicates a very good agreement with them specially for strange sea quark. Parton orbital angular momentum is also investigated. It is shown that the Q{sup 2} evolution of quark and gluon angular momentum is in good agreement with the result which can be obtained in the NLO approximation from helicity sum rule.

  9. Multimission empirical ocean tide modeling for shallow waters and polar seas

    DEFF Research Database (Denmark)

    Cheng, Yongcun; Andersen, Ole Baltazar

    2011-01-01

    A new global ocean tide model named DTU10 (developed at Technical University of Denmark) representing all major diurnal and semidiurnal tidal constituents is proposed based on an empirical correction to the global tide model FES2004 (Finite Element Solutions), with residual tides determined using...... to recover twice the spatial variations of the tidal signal which is particularly important in shallow waters where the spatial scale of the tidal signal is scaled down. Outside the +/- 66 degrees parallel combined Envisat, GEOSAT Follow-On, and ERS-2, data sets have been included to solve for the tides up...... to the +/- 82 degrees parallel. A new approach to removing the annual sea level variations prior to estimating the residual tides significantly improved tidal determination of diurnal constituents from the Sun-synchronous satellites (e. g., ERS-2 and Envisat) in the polar seas. Extensive evaluations with six...

  10. Structural elucidation of olive pomace fed sea bass (Dicentrarchus labrax) polar lipids with cardioprotective activities.

    Science.gov (United States)

    Nasopoulou, Constantina; Smith, Terry; Detopoulou, Maria; Tsikrika, Constantina; Papaharisis, Leonidas; Barkas, Dimitris; Zabetakis, Ioannis

    2014-02-15

    The purpose of this study was to structurally characterise the polar lipids of sea bass (Dicentrarchus labrax), fed with an experimental diet containing olive pomace (OP), that exhibit cardioprotective activities. OP has been added to conventional fish oil (FO) feed at 4% and this was the OP diet, having been supplemented as finishing diet to fish. Sea bass was aquacultured using either FO or OP diet. At the end of the dietary experiment, lipids in both samples of fish muscle were quantified and HPLC fractionated. The in vitro cardioprotective properties of the polar lipid fractions, using washed rabbit's platelets, have been assessed and the two most biologically active fractions were further analysed by mass spectrometry. The gas-chromatrograpy-mass spectrometric data shows that these two fractions contain low levels of myristic (14:0), oleic (18:1 cis ω-9) and linoleic acids (18:2 ω-6), but high levels of palmitic (16:0) and stearic acids (18:0) as well as eicosadienoic acid (20:2 ω-6). The first fraction (MS1) also contained significant levels of arachidonic acid (20:4 ω-6) and the omega-3 fatty acids: eicosapentaenoic acid (22:5) and docosahexaenoic acid (22:6). Electrospray-mass spectrometry elucidated that the lipid composition of the two fractions contained various diacyl-glycerophospholipids species, where the majority of them have either 18:0 or 18:1 fatty acids in the sn-1 position and either 22:6 or 20:2 fatty acids in the sn-2 position for MS1 and MS2, respectively. Our research focuses on the structure/function relationship of fish muscle polar lipids and cardiovascular diseases and structural data are given for polar lipid HPLC fractions with strong cardioprotective properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Sea-ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans.

    Science.gov (United States)

    Langbehn, Tom J; Varpe, Øystein

    2017-12-01

    Light is a central driver of biological processes and systems. Receding sea ice changes the lightscape of high-latitude oceans and more light will penetrate into the sea. This affects bottom-up control through primary productivity and top-down control through vision-based foraging. We model effects of sea-ice shading on visual search to develop a mechanistic understanding of how climate-driven sea-ice retreat affects predator-prey interactions. We adapt a prey encounter model for ice-covered waters, where prey-detection performance of planktivorous fish depends on the light cycle. We use hindcast sea-ice concentrations (past 35 years) and compare with a future no-ice scenario to project visual range along two south-north transects with different sea-ice distributions and seasonality, one through the Bering Sea and one through the Barents Sea. The transect approach captures the transition from sub-Arctic to Arctic ecosystems and allows for comparison of latitudinal differences between longitudes. We find that past sea-ice retreat has increased visual search at a rate of 2.7% to 4.2% per decade from the long-term mean; and for high latitudes, we predict a 16-fold increase in clearance rate. Top-down control is therefore predicted to intensify. Ecological and evolutionary consequences for polar marine communities and energy flows would follow, possibly also as tipping points and regime shifts. We expect species distributions to track the receding ice-edge, and in particular expect species with large migratory capacity to make foraging forays into high-latitude oceans. However, the extreme seasonality in photoperiod of high-latitude oceans may counteract such shifts and rather act as a zoogeographical filter limiting poleward range expansion. The provided mechanistic insights are relevant for pelagic ecosystems globally, including lakes where shifted distributions are seldom possible but where predator-prey consequences would be much related. As part of the discussion

  12. Using discrete choice modeling to generate resource selection functions for female polar bears in the Beaufort Sea

    Science.gov (United States)

    Durner, George M.; Amstrup, Steven C.; Nielson, Ryan M.; McDonald, Trent; Huzurbazar, Snehalata

    2004-01-01

    Polar bears (Ursus maritimus) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We explored the use of discrete choice models to describe habitat selection by female polar bears in the Beaufort Sea. Using stepwise procedures we generated resource selection models of habitat use. Sea ice characteristics and ocean depths at known polar bear locations were compared to the same features at randomly selected locations. Models generated for each of four seasons confirmed complexities of habitat use by polar bears and their response to numerous factors. Bears preferred shallow water areas where different ice types intersected. Variation among seasons was reflected mainly in differential selection of total ice concentration, ice stages, floe sizes, and their interactions. Distance to the nearest ice interface was a significant term in models for three seasons. Water depth was selected as a significant term in all seasons, possibly reflecting higher productivity in shallow water areas. Preliminary tests indicate seasonal models can predict polar bear distribution based on prior sea ice data.

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

    Science.gov (United States)

    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.

  14. Ecological change drives a decline in mercury concentrations in southern Beaufort Sea polar bears

    Science.gov (United States)

    McKinney, Melissa A.; Atwood, Todd C.; Pedro, Sara; Peacock, Elizabeth

    2017-01-01

    We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g–1 dry weight (mean: 3.5 ± 0.2 μg g–1). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-of-the-year ≈ 2 year old dependent cubs. No variation was observed between spring and fall samples. For spring-sampled adults, THg concentrations declined by 13% per year, contrasting recent trends observed for other Western Hemispheric Arctic biota. Concentrations also declined by 15% per year considering adult males only, while a slower, nonsignificant decrease of 4.4% per year was found for adult females. Lower THg concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position food resources consumed. Because BMI and diet were related, and the relationship to THg was strongest for BMI, trends were re-evaluated adjusting for BMI as the covariate. The adjusted annual decline was not significant. These findings indicate that changes in foraging ecology, not declining environmental concentrations of mercury, are driving short-term declines in THg concentrations in southern Beaufort Sea polar bears.

  15. Numerical simulation study of polar low in Kara sea: developing mechanisms evaluation

    Science.gov (United States)

    Verezemskaya, Polina; Stepanenko, Victor

    2016-04-01

    The study focuses on investigating the mechanisms of interaction between potential vorticity's anomalies and latent heat release as polar low development factors. The polar low observed in Kara sea 29th -30th September 2008 is analyzed using numerical modeling (WRF ARW model) and observational data (IR cloudiness and microwave water vapor and surface wind speeds from MODIS (Aqua)). Two numerical experiments with 5 km spatial resolution were conducted with microphisical scheme turned on and off to assess the role of latent heat on vortex intensification. The quality of modelling was estimated by comparing WRF output and the satellite data. Based on reference experiment (with microphysical parameterization turned on) and observational data PL developed in vertically stable, non-baroclinic atmosphere and characterized by very low surface heat fluxes. «Dry» experiment results suggests that without latent heat source in the middle troposphere polar low intensifies slower, than in reality. In order to divide low- and upper-level forcing within PL dynamics we used attribution concept based on the quasi-geostrophic omega-equation. To ensure that QG theory is applicable for this PL case, we estimate correlation between the modeled and QG vertical speed field obtained from omega-equation using finite-differences method.

  16. Assessment of the Aquarius Space-borne Sea Surface Salinity Retrievals in Polar Ocean

    Science.gov (United States)

    Dinnat, E.; Brucker, L.; Caraballo Álvarez, I. O.

    2014-12-01

    Ocean salinity and temperature drive the thermohaline circulation and play a key role in the ocean-atmosphere coupling. With the availability of passive L-band (1.4 GHz) space-borne observations, Sea Surface Salinity (SSS) can be monitored globally at weekly time scales. SSS in the polar regions may be used to better constrain deep water formation, and to monitor changes due to freshening by the melting cryosphere. However, SSS remote sensing in the polar oceans is challenging because L-band radiometric observations are less sensitive to salinity in cold waters, SSS retrieval is less accurate for very rough seas and the presence of sea ice, icebergs and land in the radiometer field of view adds complexity to the retrieval process. Aquarius is a NASA space-borne instrument operating three L-band radiometers. While Aquarius SSS retrievals are performed with a good accuracy in tropical and mid-latitude oceans, a thorough assessment has not been performed in the colder waters of the polar oceans. To assess Aquarius data at high latitudes, we compare them to in-situ measurements from ship cruises. In the northern hemisphere, cruises between Denmark and Greenland are used. In the south, we use cruises in the Austral Ocean between Tasmania and Antarctica. These quality-controlled shipborne measurements (more extensive than the Argo profiling floats which are rare at high latitudes) allow us to assess Aquarius SSS over long transects, repeated weekly or monthly, over the three year period during which Aquarius has been operating. Our results show that significant contamination of SSS retrievals by ice and land are observed, despite the correction for land contamination applied in the Aquarius retrieval algorithm. Such long track comparisons with ship data will help refine the future versions of Aquarius space-borne products. Nonetheless, excluding the data contaminated by land or ice, the agreement with ship data is good. Specifically, the standard deviation is ~0.3 - 0

  17. IOCCG Report Number 16, 2015 Ocean Colour Remote Sensing in Polar Seas . Chapter 2; The Polar Environment: Sun, Clouds, and Ice

    Science.gov (United States)

    Comiso, Josefino C.; Perovich, Don; Stamnes, Knut; Stuart, Venetia (Editor)

    2015-01-01

    The polar regions are places of extremes. There are months when the regions are enveloped in unending darkness, and months when they are in continuous daylight. During the daylight months the sun is low on the horizon and often obscured by clouds. In the dark winter months temperatures are brutally cold, and high winds and blowing snow are common. Even in summer, temperatures seldom rise above 0degC. The cold winter temperatures cause the ocean to freeze, forming sea ice. This sea ice cover acts as a barrier limiting the transfer of heat, moisture, and momentum between the atmosphere and the ocean. It also greatly complicates the optical signature of the surface. Taken together, these factors make the polar regions a highly challenging environment for optical remote sensing of the ocean.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  19. Remotely Operated Vehicles under sea ice - Experiences and results from five years of polar operations

    Science.gov (United States)

    Katlein, Christian; Arndt, Stefanie; Lange, Benjamin; Belter, Hans Jakob; Schiller, Martin; Nicolaus, Marcel

    2016-04-01

    The availability of advanced robotic technologies to the Earth Science community has largely increased in the last decade. Remotely operated vehicles (ROV) enable spatially extensive scientific investigations underneath the sea ice of the polar oceans, covering a larger range and longer diving times than divers with significantly lower risks. Here we present our experiences and scientific results acquired from ROV operations during the last five years in the Arctic and Antarctic sea ice region. Working under the sea ice means to have all obstacles and investigated objects above the vehicle, and thus changes several paradigms of ROV operations as compared to blue water applications. Observations of downwelling spectral irradiance and radiance allow a characterization of the optical properties of sea ice and the spatial variability of the energy partitioning across the atmosphere-ice-ocean boundary. Our results show that the decreasing thickness and age of the sea ice have led to a significant increase in light transmission during summer over the last three decades. Spatially extensive measurements from ROV surveys generally provide more information on the light field variability than single spot measurements. The large number of sampled ice conditions during five cruises with the German research icebreaker RV Polarstern allows for the investigations of the seasonal evolution of light transmittance. Both, measurements of hyperspectral light transmittance through sea ice, as well as classification of upward-looking camera images were used to investigate the spatial distribution of ice-algal biomass. Buoyant ice-algal aggregates were found to be positioned in the stretches of level ice, rather than pressure ridges due to a physical interaction of aggregate-buoyancy and under-ice currents. Synchronous measurements of sea ice thickness by upward looking sonar provides crucial additional information to put light-transmittance and biological observations into context

  20. Anoxic Decomposition in Sediments from a Tropical Mangrove Forest and the Temperate Wadden Sea: Implications of N and P Addition Experiments

    Science.gov (United States)

    Holmboe, N.; Kristensen, E.; Andersen, F. Ø.

    2001-08-01

    The anoxic decomposition processes in sediments from a tropical mangrove forest (Bangrong, Thailand) and a salt marsh in the temperate Wadden Sea (Denmark) were compared, and the effects of increased ammonium and/or phosphate concentrations on the anoxic decomposition were studied. Sediment was incubated in jars (20-ml glass vials) and changes in porewater solutes were followed in a time series of 3 weeks. Furthermore, the short-term fate (days) of dissolved inorganic phosphate (DIP) added to Bangrong mangrove sediment was evaluated from phosphorus fractionation. Although the organic matter at both study sites had relatively high C:N and C:P ratios, the anoxic sediment decomposition was not affected by nutrient enrichments at the level applied in this study. The sediment metabolism (TCO 2and DOC production, and sulfate consumption) was 5-10 times higher in Wadden Sea sediment than in Bangrong mangrove sediment, probably due to the higher content of structural carbohydrates (e.g. cellulose) as indicated by higher C:N and C:P ratios in mangrove organic matter. This is substantiated by a lower nutrient release from Bangrong mangrove sediments and suggests a faster turnover of N and P by nutrient deficient bacteria in the mangrove sediment. DIP was released during anoxic decomposition in Wadden Sea sediment, but was retained in Bangrong mangrove sediment. Analysis of phosphorus fractions in Bangrong mangrove sediment revealed that added excess DIP was efficiently taken up by the sediment particles and primarily retrieved in the easily exchangeable and iron bound fractions. The studied mangrove forest sediment seems to be a phosphorus sink.

  1. Increasing nest predation will be insufficient to maintain polar bear body condition in the face of sea ice loss.

    Science.gov (United States)

    Dey, Cody J; Richardson, Evan; McGeachy, David; Iverson, Samuel A; Gilchrist, Hugh G; Semeniuk, Christina A D

    2017-05-01

    Climate change can influence interspecific interactions by differentially affecting species-specific phenology. In seasonal ice environments, there is evidence that polar bear predation of Arctic bird eggs is increasing because of earlier sea ice breakup, which forces polar bears into nearshore terrestrial environments where Arctic birds are nesting. Because polar bears can consume a large number of nests before becoming satiated, and because they can swim between island colonies, they could have dramatic influences on seabird and sea duck reproductive success. However, it is unclear whether nest foraging can provide an energetic benefit to polar bear populations, especially given the capacity of bird populations to redistribute in response to increasing predation pressure. In this study, we develop a spatially explicit agent-based model of the predator-prey relationship between polar bears and common eiders, a common and culturally important bird species for northern peoples. Our model is composed of two types of agents (polar bear agents and common eider hen agents) whose movements and decision heuristics are based on species-specific bioenergetic and behavioral ecological principles, and are influenced by historical and extrapolated sea ice conditions. Our model reproduces empirical findings that polar bear predation of bird nests is increasing and predicts an accelerating relationship between advancing ice breakup dates and the number of nests depredated. Despite increases in nest predation, our model predicts that polar bear body condition during the ice-free period will continue to decline. Finally, our model predicts that common eider nests will become more dispersed and will move closer to the mainland in response to increasing predation, possibly increasing their exposure to land-based predators and influencing the livelihood of local people that collect eider eggs and down. These results show that predator-prey interactions can have nonlinear responses to

  2. Reproductive strategies in female polar and deep-sea bobtail squid genera Rossia and Neorossia (Cephalopoda: Sepiolidae)

    NARCIS (Netherlands)

    Laptikhovsky, V. V.; Nigmatullin, Ch. M.; Hoving, H. J. T.; Onsoy, B.; Salman, A.; Zumholz, K.; Shevtsov, G. A.

    2008-01-01

    Female reproductive features have been investigated in five polar and deep-sea bobtail squid genera Rossia and Neorossia (R. macrosoma, R. moelleri, R. pacifica, N.c. caroli and N.c. jeannae). These species are characterized by asynchronous ovary maturation, very large eggs (> 10% ML), fecundity of

  3. Comparison of radiance and polarization values observed in the Mediterranean Sea and simulated in a Monte Carlo model

    DEFF Research Database (Denmark)

    Adams, J.T.; Aas, E.; Højerslev, N.K.

    2002-01-01

    Measurements of the radiance and degree of polarization made in 1971 in the Mediterranean Sea are presented along with the simulation of all observed quantities by a Monte Carlo technique. It is shown that our independent scattering treatment utilizing a Stokes vector formalism to describe...

  4. Low temporal variation in the intact polar lipid composition of North Sea coastal marine water reveals limited chemotaxonomic value

    NARCIS (Netherlands)

    Brandsma, J.; Hopmans, E.C.; Philippart, C.J.M.; Veldhuis, M.J.W.; Schouten, S.; Sinninghe Damsté, J.S.S.

    2012-01-01

    Temporal variations in the abundance and composition of intact polar lipids (IPLs) in North Sea coastal marine water were assessed over a one-year seasonal cycle, and compared with environmental parameters and the microbial community composition. Sulfoquinovosyldiacylglycerol (SQDG) was the most

  5. Spatial distribution of intact polar lipids in North Sea surface waters: Relationship with environmental conditions and microbial community composition

    NARCIS (Netherlands)

    Brandsma, J.; Hopmans, E.C.; Brussaard, C.P.D.; Witte, H.J.; Schouten, S.; Sinninghe Damsté, J.S.

    2012-01-01

    We characterized and quantified the intact polar lipid (IPL) composition of the surface waters of the North Sea and investigated its relationships with environmental conditions, microbial abundances, and community composition. The total IPL pool comprised at least 600 different IPL species in seven

  6. Arctic sea ice melt, the Polar vortex, and mid-latitude weather: Are they connected?

    Science.gov (United States)

    Vihma, Timo; Overland, James; Francis, Jennifer; Hall, Richard; Hanna, Edward; Kim, Seong-Joong

    2015-04-01

    The potential of recent Arctic changes to influence broader hemispheric weather is a difficult and controversial topic with considerable skepticism, as time series of potential linkages are short (<10 years) and the signal-to-noise ratio relative to chaotic weather events is small. A way forward is through further understanding of potential atmospheric dynamic mechanisms. Although not definitive of change in a statistical or in a causality sense, the exceptionally warm Arctic winters since 2007 do contain increased variability according to some climate indices, with six negative (and two positive) Arctic Oscillation atmospheric circulation index events that created meridional flow reaching unusually far north and south. High pressure anomalies developed east of the Ural Mountains in Russia in response to sea-ice loss in the Barents/Kara Seas, which initiated eastward-propagating wave trains of high and low pressure that advected cold air over central and eastern Asia. Increased Greenland blocking and greater geopotential thickness related to low-level temperatures increases led to northerly meridional flow into eastern North America, inducing persistent cold periods. Arctic connections in Europe and western North America are less clear. The quantitative impact of potential Arctic change on mid-latitude weather will not be resolved within the foreseeable future, yet new approaches to high-latitude atmospheric dynamics can contribute to improved extended range forecasts as outlined by the WMO/Polar Prediction Program and other international activities.

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

    Science.gov (United States)

    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.

  8. Changes over 50 years in fish fauna of a temperate coastal sea: Degradation of trophic structure and nursery function

    NARCIS (Netherlands)

    van der Veer, H.W.; Dapper, R.; Henderson, P.A.; Jung, A.S.; Philippart, C.J.M.; Witte, J.IJ.; Zuur, A.F.

    2015-01-01

    The ongoing daily sampling programme of the fish fauna in the Dutch Wadden Sea using fixed gear was analysed for the years 1960–2011. Spring sampling caught immigrating fish from the coastal zone and autumn samples reflected emigration of young-of-the-year. In total 82 fish species were caught with

  9. Sedimentary Processes of Unstable Ice Sheet Grounding Zones: Comparing Polar and Temperate Grounding Zone Wedges Using Marine Geophysical Data and Outcrop Studies

    Science.gov (United States)

    Demet, B. P.; Anderson, J. B.; Nittrouer, J. A.; Simkins, L.; Halberstadt, A. R.; Prothro, L. O.

    2015-12-01

    Current understanding of ice sheet grounding zone dynamics is limited because direct observation of grounding zones and their deposits (grounding zone wedges, GZW) is restricted to marine geophysical methods, which provide large-scale measurements of planform morphology and internal stratigraphy, but little information regarding sedimentary architecture. Seismic data nevertheless reveal that GZW range meters to kilometers in length scale and typically possess foresets and incised channels. Sediment cores from measured wedges are helpful for evaluating vertical changes in stratigraphy, but leave significant uncertainty regarding the spatial variability of deposits and the nature of their contacts, which are necessary data to evaluate sedimentary processes operating within grounding zones. This study presents results from outcrop studies of GZW exposed in sea cliffs of the Puget Sound, Washington (U.S.A.), where a series of back-stepping GZW record rapid grounding line retreat of the Puget Lobe. These outcrops are used to evaluate first-order physical controls on depositional processes. The data are compared to geophysical observations and cores collected from the Ross Sea, Antarctic, to evaluate similarities between the outcrop-scale deposits and polar grounding zone wedges that possess wavelengths measuring several kilometers, and amplitudes of tens of meters. The preliminary results show that for these larger features, wedge progradation is facilitated by foreset deposition. Alternatively, for small-scale wedges (100's of m wavelength, m-scale amplitudes), wedge development occurs through topset aggradation. Additionally, based on the Puget Sound GZW deposits, progradation arises due to sediment gravity flows on the foreset. Sand and silt couplets, preserved within wedge foresets, suggest that tidal pumping occurred under ice, producing deposits between punctuated sediment gravity flows. These data show a multitude of sedimentary and morphological scales that are

  10. Effects of earlier sea ice breakup on survival and population size of polar bears in western Hudson Bay

    Science.gov (United States)

    Regehr, E.V.; Lunn, N.J.; Amstrup, Steven C.; Stirling, I.

    2007-01-01

    Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population-level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack-Jolly-Seber capture-recapture models to estimate population size and survival for polar bears (Ursus maritimus), one of the most ice-dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020-1,368) in 1987 to 935 (95% CI = 794-1,076) in 2004. Total apparent survival of prime-adult polar bears (5-19 yr) was stable for females (0.93; 95% CI = 0.91-0.94) and males (0.90; 95% CI = 0.88-0.91). Survival of juvenile, subadult, and senescent-adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human-polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as

  11. Sea Surface Temperatures Mediated by the El Niño-Southern Oscillation Affect Birds Breeding in Temperate Coastal Rain Forests

    Directory of Open Access Journals (Sweden)

    Anthony J. Gaston

    2005-12-01

    Full Text Available We studied the timing of breeding and juvenile/adult ratios among songbirds in temperate rain forests over four years on the Haida Gwaii (Queen Charlotte Islands archipelago, British Columbia. In May 1998, air temperatures in Haida Gwaii were above average, whereas in 1999 they were the lowest in 20 yr: temperatures in the other two years were closer to normal, although 2001 was almost as cold as 1999. Temperatures closely followed the patterns of sea surface temperatures created by the 1997-1998 El Niño, i.e., warm, event and the subsequent strong La Niña, i.e., cool, event. Timing of breeding, as measured by the first capture of juveniles or by direct observations of hatching, varied by approximately 19 d between the earliest (1998 and latest (1999 years. In 1998, the proportion of juveniles among birds trapped increased steeply as soon as young birds began to appear. In other years, the rate of increase was slower. In 1999, the peak proportions of hatching-year individuals among the foliage-gleaning insectivores, i.e., the Orange-crowned Warbler (Vermivora celata, Townsend's Warbler (Dendroica townsendi, and the Golden-crowned Kinglet (Regulus satrapa, were lower than in other years, with almost no young Orange-crowned Warblers captured at all. The pattern of variation in the timing of breeding and in the proportion of hatching-year individuals trapped fitted the temperature data well, although rainfall may also have contributed. We concluded that changes mediated by El Niño-Southern Oscillation (ENSO in sea surface temperatures off northern British Columbia, through their effects on air temperatures, had a strong effect on the breeding of forest birds, to the point of causing nearly complete reproductive failure for one species in 1999. An intensification of the ENSO cycle could lead to more erratic reproduction for some species.

  12. Seasonal Stability in the Microbiomes of Temperate Gorgonians and the Red Coral Corallium rubrum Across the Mediterranean Sea

    KAUST Repository

    van de Water, Jeroen A. J. M.

    2017-07-05

    Populations of key benthic habitat-forming octocoral species have declined significantly in the Mediterranean Sea due to mass mortality events caused by microbial disease outbreaks linked to high summer seawater temperatures. Recently, we showed that the microbial communities of these octocorals are relatively structured; however, our knowledge on the seasonal dynamics of these microbiomes is still limited. To investigate their seasonal stability, we collected four soft gorgonian species (Eunicella singularis, Eunicella cavolini, Eunicella verrucosa and Leptogorgia sarmentosa) and the precious red coral (Corallium rubrum) from two coastal locations with different terrestrial impact levels in the Mediterranean Sea, and used next-generation amplicon sequencing of the 16S rRNA gene. The microbiomes of all soft gorgonian species were dominated by the same \\'core microbiome\\' bacteria belonging to the Endozoicomonas and the Cellvibrionales clade BD1-7, whereas the red coral microbiome was primarily composed of \\'core\\' Spirochaetes, Oceanospirillales ME2 and Parcubacteria. The associations with these bacterial taxa were relatively consistent over time at each location for each octocoral species. However, differences in microbiome composition and seasonal dynamics were observed between locations and could primarily be attributed to locally variant bacteria. Overall, our data provide further evidence of the intricate symbiotic relationships that exist between Mediterranean octocorals and their associated microbes, which are ancient and highly conserved over both space and time, and suggest regulation of the microbiome composition by the host, depending on local conditions.

  13. A new source of Southern Ocean and Antarctic aerosol from tropospheric polar cell chemistry of sea ice emissions

    Science.gov (United States)

    Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Robinson, A. D.; Harris, N. R. P.; Keywood, M.; Ward, J.; Galbally, I.; Molloy, S.; Thomas, A.; Wilson, S. R.

    2014-12-01

    The Antarctic region is a pristine environment with minimal anthropogenic influence. Aerosol measurements in this environment allow the study of natural aerosols and polar atmospheric dynamics. Measurements in this region have been limited primarily to continental and coastal locations where permanent stations exist, with a handful of measurements in the sea ice region. The MAPS campaign (Measurements of Aerosols and Precursors during SIPEXII) occurred as part of SIPEX II (Sea Ice Physics and Ecosystems eXperiment II) voyage in Spring, 2012, and produced the first Antarctic pack-ice focused aerosol dataset aimed at characterizing new particle formation processes off the coast of East Antarctica (~65°S, 120°E). Numerous atmospheric parameters and species were measured, including the number of aerosol particles in the 3-10 nm size range, the range associated with nucleating particle formation. A latitudinal transect through the sea ice identified the Polar Front from sudden changes in nucleating particle concentrations, averaging 51cm-3 north of the front in the Ferrel cell, and 766 cm-3 south of the front, in the Polar cell region. The Polar Front location was also confirmed by meteorological and back-trajectory data. Background aerosol populations in the Polar cell fluctuated significantly but displayed no growth indicators, suggesting transport. Back-trajectories revealed that air parcels often descended from the free-troposphere within the previous 24-48 hrs. It is proposed that particle formation occurs in the free troposphere from precursors uplifted at the polar front region which, being a sea-ice/ocean region, is a significant precursor source. After tropospheric formation, populations descending at the poles are transported northward and reach the sea ice surface, missing continental stations. Current measurements of Antarctic aerosol suggest very low loading which may be explained by these circulation patterns and may underestimate total regional loading

  14. Life-history traits of temperate and thermophilic barracudas (Teleostei: Sphyraenidae) in the context of sea warming in the Mediterranean Sea.

    Science.gov (United States)

    Villegas-Hernández, H; Muñoz, M; Lloret, J

    2014-06-01

    This study indicated that the life-history traits of European barracuda Sphyraena sphyraena are apparently better suited to their environmental conditions compared to the more physically restricted life-history traits of the yellow-mouth barracuda Sphyraena viridensis, which co-habit the north-western Mediterranean Sea. The latter thermophilic species has a considerably higher reproductive potential as it invests its energy reserves in larger numbers of hydrated eggs per spawning batch. This would favour its population growth rates within the study area, especially if sea warming continues, in which case it is likely that the spawning phenology of this species would give it an advantage. © 2014 The Fisheries Society of the British Isles.

  15. Investigating Ecosystem Pattern and Process Across a Land-Sea Gradient: A New Coastal Margin Observatory in the Pacific Coastal Temperate Rainforest

    Science.gov (United States)

    Giesbrecht, I.; Lertzman, K. P.; Oliver, A. A.; Tank, S. E.; Floyd, B. C.; Frazer, G. W.; Hunt, B. P.; Kellogg, C.; Heger, T.; Levy-Booth, D.; Mohn, W. H.; Hallam, S. J.; Keeling, P.; Sanborn, P.; Brunsting, R.; D'Amore, D. V.

    2015-12-01

    Terrestrial organic matter exported from coastal watersheds influences marine ecosystems and carbon budgets across the globe, yet much is unknown about the fundamental processes of land-sea carbon cycling or system response to climate change. On two outer-coast islands near the center of the Pacific Coastal Temperate Rainforest (PCTR), the Hakai Institute has established a coastal margin observatory to examine the flux of terrestrial organic matter from land to sea - the origins, pathways, processes and marine consequences - in the context of long-term environmental change. The outer-coast PCTR is characterized by an ocean-moderated climate, subdued terrain, extensive wetlands and lower forest productivity than the mountainous mainland coast. Here we give an overview of, and initial results from, a new long-term multi-disciplinary investigation of processes that link PCTR watersheds with the carbon balance and food web of northeastern subarctic Pacific coastal waters. Beginning in 2013, we established year-round sampling and a sensor network to quantify - at high temporal resolution - the amount and character of terrestrial exports from seven focal watersheds on Calvert and Hecate Islands, British Columbia. Early results show that freshwater dissolved organic carbon concentrations are high on average, fluctuate temporally and vary spatially across watersheds. A real-time hydrological sensor network shows rapid responses of stream stages and soil water tables to rainfall inputs. Carbon export can vary greatly with stream discharge in these flashy systems. We use paired marine monitoring stations at stream outlets to concurrently track ocean conditions and to trace terrestrial organic matter. Across a larger set of watersheds, we examine the role of catchment topography, hydrology and composition in controlling biogeochemical exports. On land, we use airborne LiDAR data to evaluate landscape controls on vegetation height - a proxy for forest productivity and biomass

  16. Gluons and the quark sea at high energies: distributions, polarization, tomography

    Energy Technology Data Exchange (ETDEWEB)

    Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.

    2011-09-30

    This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

  17. Polar Frontal Zone of the Barents Sea Western Trough Based on the Direct Measurements in 2007

    Directory of Open Access Journals (Sweden)

    A.N. Morozov

    2017-04-01

    Full Text Available The results of measurements carried out in summer, 2007 in the north-western part of the Barents Sea are discussed. The ship weather station and the vessel mounted Acoustic Doppler current profiler VMADCP150 are used to carry out measurements in the vessel motion. CTD/LADCP-sensing is performed at the drift stations. The minimum horizontal scale of a temperature front is 0.5 km, whereas the maximum horizontal gradient of water temperature is 4 °C/km. The width of the North Cape Current Northern branch is ~8 km that is three times larger than the Rossby radius of deformation. Position of the temperature front coincides with that of the jet stream core. The characteristics of small-scale vertical structure of water dynamics and density stratification in the polar frontal zone are discussed. The averaged annual variability of temperature and salinity vertical structure in the area of the Spitsbergen Bank and the Hopen Deep are represented. The intra-annual variability of water salinity in the Hopen Deep calculated based on the historical database of hydrological data, revealed the presence of variations with a period of four months. Based on satellite observations, position of the temperature front in the area of research is defined.

  18. Gluons and the quark sea at high energies: distributions, polarization, tomography

    CERN Document Server

    Boer, D; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Sassot, R.; Zurita, P.; Cherednikov, I.O.; Goncalves, V.P.; Sandapen, R.; Kopeliovich, B.Z.; Gao, J.-H.; Liang, Z.-T.; Passek-Kumericki, K.; Kumericki, K.; Lappi, T.; Wallon, S.; Pire, B.; Geraud, R.; Moutarde, H.; Gelis, F.; Soyez, G.; Meskauskas, M.; Mueller, Dieter; Stefanis, N.G.; Gallmeister, K.; Mosel, U.; Diehl, M.; Bartels, J.; Pirner, H.J.; Hagler, P.; Jager, B.; Spiesberger, H.; Lautenschlager, T.; Schafer, A.; Ringer, F.; Vogelsang, W.; Kroll, P.; Alekhin, S.; Blumlein, J; Moch, S.-O.; Pisano, C.; Rojo, J.; Bacchetta, A.; Pasquini, B.; Radici, M.; Ciofi degli Atti, C.; Mezzetti, C.B.; Kaptari, L.P.; Anselmino, M.; Tanaka, K.; Koike, Y.; Kumano, S.; Motyka, L.; Golec-Biernat, K.; Stasto, A.M.; Golec-Biernat, K.; Szymanowski, L.; Cherednikov, I.O.; Kaptari, L.P.; Radyushkin, A.; Alekhin, S.; Kondratenko, A.; Horowitz, W.A.; Schnell, G.; Chevtsov, P.; Mulders, P.J.; Rogers, T.C.; Boer, D.; Forshaw, J.R.; Cooper-Sarkar, A.; Chirilli, G.A.; Muller, D.; Wang, X.-N.; Yuan, F.; Qian, X.; Brodsky, S.J.; Schweitzer, P.; Horn, T.; Tuchin, K.; Dupre, R.; Erdelyi, B.; Manikonda, S.; Ostrumov, P.N.; Abeyratne, S.; Erdelyi, B.; Vossen, A.; Riordan, S.; Tsentalovich, E.; Goldstein, G.R.; Pozdeyev, E.; Huang, M.; Aidala, C.; Dumitru, A.; Dominguez, F.; Ben-Zvi, I.; Deshpande, A.; Faroughy, C.; Hammons, L.; Hao, Y.; Johnson, E.C.; Litvinenko, V.N.; Taneja, S.; Tsoupas, N.; Webb, S.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M.M.; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Ptitsyn, V.; Rao, T.; Roser, T.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Zelenski, A.; Beuf, G.; Burton, T.; Debbe, R.; Fazio, S.; Marciano, W.J.; Qiu, J.-W.; Toll, T.; Ullrich, T.; Deshpande, A.; Dumitru, A.; Kang, Z.-B.; Stasto, A.M.; Yuan, F.; Kovchegov, Y.V.; Majumder, A; Metz, A.; Zhou, J.; Gamberg, L.; Stasto, A.M.; Strikman, M.; Xiao, B.-W.; Guzzi, M.; Nadolsky, P.; Olness, F.; BC, H.; Liuti, S.; Ahmed, S.; Bogacz, A.; Derbenev, Ya.; Hutton, A.; Krafft, G.; Li, R.; Marhauser, F.; Morozov, V.; Pilat, F.; Rimmer, R.; Satogata, T.; Sullivan, M.; Spata, M.; Terzic, B.; Wang, H.; Yunn, B.; Zhang, Y.; Avakian, H.; Musch, B.; Nadel-Turonski, P.; Prokudin, A.; Radyushkin, A.; Weiss, C.; Krafft, G.; Radyushkin, A.; Sayed, H.; Gilfoyle, G.P.; Cloet, I.C.; Miller, G.; Gonderinger, M.

    2011-01-01

    This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific op...

  19. Air flow and dry deposition of non-sea salt sulfate in polar firn: Paleoclimatic implications

    Science.gov (United States)

    Cunningham, J.; Waddington, E. D.

    Non-sea salt sulfate aerosol (NSS) is an important factor for the Earth's albedo because it backscatters solar radiation and is the major cloud condensation nucleus over oceans. At Vostok, Antarctica, NSS concentration shows an increase in glacial period ice of 20-46% that cannot be attributed to changes in accumulation rate. The additional NSS may be due to enhanced dry deposition of NSS by topographic windpumping during the windy glacial periods. We model the volume flux of air into snow due to barometric pressure changes and air flow over surface microrelief. The Gormley-Kennedy equation approximately describes how aerosols advected into the snow pack are removed from the air by diffusion to the snow matrix. Barometric pressure and wind speed data from several polar sites have been used to quantify the vertical volume flux of air and mass flux of NSS. Model results indicate that air flow over small sastrugi, wind carved snow dunes commonly found on ice caps, is the dominant dry deposition mechanism for NSS. Paleo wind speed and surface roughness can significantly influence the aerosol record in ice cores.

  20. A Climatology of Polar Low Occurrences in the Nordic Seas and an Examination of Katabatic Winds as a Triggering Mechanism

    Science.gov (United States)

    1992-12-01

    associated with the maximum SST gradient. 8 Using National Meteorological Center ( NMC ) gridded field data, Businger compiled the average deviations of 500...and initiates the convection and shower-type precipitation. Polar lows were thought to form through the merging of numerous convective cells into a...imagery. Strong vertical entropy gradients from sensible heat flux resulting from the strong air-sea temperature 128 differences can support extreme

  1. Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century.

    Science.gov (United States)

    Castro de la Guardia, Laura; Derocher, Andrew E; Myers, Paul G; Terwisscha van Scheltinga, Arjen D; Lunn, Nick J

    2013-09-01

    The primary habitat of polar bears is sea ice, but in Western Hudson Bay (WH), the seasonal ice cycle forces polar bears ashore each summer. Survival of bears on land in WH is correlated with breakup and the ice-free season length, and studies suggest that exceeding thresholds in these variables will lead to large declines in the WH population. To estimate when anthropogenic warming may have progressed sufficiently to threaten the persistence of polar bears in WH, we predict changes in the ice cycle and the sea ice concentration (SIC) in spring (the primary feeding period of polar bears) with a high-resolution sea ice-ocean model and warming forced with 21st century IPCC greenhouse gas (GHG) emission scenarios: B1 (low), A1B (medium), and A2 (high). We define critical years for polar bears based on proposed thresholds in breakup and ice-free season and we assess when ice-cycle conditions cross these thresholds. In the three scenarios, critical years occur more commonly after 2050. From 2001 to 2050, 2 critical years occur under B1 and A2, and 4 under A1B; from 2051 to 2100, 8 critical years occur under B1, 35 under A1B and 41 under A2. Spring SIC in WH is high (>90%) in all three scenarios between 2001 and 2050, but declines rapidly after 2050 in A1B and A2. From 2090 to 2100, the mean spring SIC is 84 (±7)% in B1, 56 (±26)% in A1B and 20 (±13)% in A2. Our predictions suggest that the habitat of polar bears in WH will deteriorate in the 21st century. Ice predictions in A1B and A2 suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century. © 2013 John Wiley & Sons Ltd.

  2. Burial and exhumation of temperate bedrock reefs as elucidated by repetitive high-resolution sea floor sonar surveys: Spatial patterns and impacts to species' richness and diversity

    Science.gov (United States)

    Storlazzi, Curt D.; Fregoso, Theresa A.; Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Finlayson, David P.

    2013-01-01

    To understand how chronic sediment burial and scour contribute to variation in the structure of algal and invertebrate communities on temperate bedrock reefs, the dynamics of the substrate and communities were monitored at locations that experience sand inundation and adjacent areas that do not. Co-located benthic scuba-transect surveys and high-resolution swath-sonar surveys were completed on bedrock reefs on the inner shelf of northern Monterey Bay, CA, in early winter 2009, spring 2010, and summer 2010. Analysis of the sonar surveys demonstrates that during the 8 months over which the surveys were conducted, 19.6% of the study area was buried by sand while erosion resulted in the exposure of bedrock over 13.8% of the study area; the remainder underwent no change between the surveys. Substrate classifications from the benthic transect surveys correlated with classifications generated from the sonar surveys, demonstrating the capacity of high-resolution sonar surveys to detect burial of bedrock reefs by sediment. On bedrock habitat that underwent burial and exhumation, species' diversity and richness of rock-associated sessile and mobile organisms were 50–66% lower as compared to adjacent stable bedrock habitat. While intermediate levels of disturbance can increase the diversity and richness of communities, these findings demonstrate that burial and exhumation of bedrock habitat are sources of severe disturbance. We suggest that substrate dynamics must be considered when developing predictions of benthic community distributions based on sea floor imagery. These results highlight the need for predictive models of substrate dynamics and for a better understanding of how burial and exhumation shape benthic communities.

  3. Temper Foam

    Science.gov (United States)

    1981-01-01

    Fabricated by Expanded Rubber & Plastics Corporation, Temper Foam provides better impact protection for airplane passengers and enhances passenger comfort on long flights because it distributes body weight and pressure evenly over the entire contact area. Called a "memory foam" it matches the contour of the body pressing against it and returns to its original shape once the pressure is removed. As a shock absorber, a three-inch foam pad has the ability to absorb the impact of a 10-foot fall by an adult. Applications include seat cushioning for transportation vehicles, padding for furniture and a variety of athletic equipment medical applications including wheelchair padding, artificial limb socket lining, finger splint and hand padding for burn patients, special mattresses for the bedridden and dental stools. Production and sales rights are owned by Temper Foam, Inc. Material is manufactured under license by the Dewey and Almy Division of Grace Chemical Corporation. Distributors of the product are Kees Goebel Medical Specialties, Inc. and Alimed, Inc. They sell Temper Foam in bulk to the fabricators who trim it to shapes required by their customers.

  4. Strong linkage of polar cod ( Boreogadus saida ) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses

    NARCIS (Netherlands)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke

    2017-01-01

    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1–2 years) are often associated with the underside of sea ice. To

  5. Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Boer, Daniel; /Groningen U.; Diehl, Markus; /DESY; Milner, Richard; /MIT; Venugopalan, Raju; /Brookhaven; Vogelsang, Werner; /Tubingen U.; Kaplan, David; /Washington U., Seattle; Montgomery, Hugh; /Jefferson Lab; Vigdor, Steven; /Brookhaven; Accardi, A.; /Jefferson Lab; Aschenauer, E.C.; /Brookhaven; Burkardt, M.; /New Mexico State U.; Ent, R.; /Jefferson Lab; Guzey, V.; /Jefferson Lab; Hasch, D.; /Frascati; Kumar, K.; /Massachusetts U., Amherst; Lamont, M.A.C.; /Brookhaven; Li, Ying-chuan; /Brookhaven; Marciano, W.; /Brookhaven; Marquet, C.; /CERN; Sabatie, F.; /IRFU, SPhN, Saclay; Stratmann, M.; /Brookhaven /LBL, Berkeley /Buenos Aires U. /Antwerp U. /Pelotas U. /Moncton U. /Santa Maria U., Valparaiso /CCTVal, Valparaiso /Hefei, CUST /Shandong U., Weihai /Boskovic Inst., Zagreb /Zagreb U., Phys. Dept. /Jyvaskyla U. /Orsay, LPT /Paris U., VI-VII /Ecole Polytechnique, CPHT /IRFU, SPhN, Saclay /Saclay, SPhT /Ruhr U., Bochum /Giessen U. /DESY /Hamburg U., Inst. Theor. Phys. II /Heidelberg U. /Mainz U., Inst. Kernphys. /Mainz U., Inst. Phys. /Regensburg U. /Tubingen U. /Wuppertal U. /DESY /Cagliari U. /INFN, Cagliari /Frascati /Milan U. /INFN, Milan /INFN, Pavia /Pavia U. /INFN, Perugia /Perugia U.; /more authors..

    2012-06-07

    the brightest femtoscope scale lepton-collider ever, exceeding the intensity of the HERA collider a thousand fold. HERA, with its center-of-mass (CM) energy of 320 GeV, was built to search for quark substructure. An EIC, with its scientific focus on studying QCD in the regime where the sea quarks and gluons dominate, would have a lower CM energy. In a staged EIC design, the CM energy will range from 50-70 GeV in stage I to approximately twice that for the full design. In addition to being the first lepton collider exploring the structure of polarized protons, an EIC will also be the first electron-nucleus collider, probing the gluon and sea quark structure of nuclei for the first time. Following the same structure as the scientific discussions at the INT, this report is organized around the following four major themes: (1) The spin and flavor structure of the proton; (2) Three dimensional structure of nucleons and nuclei in momentum and configuration space; (3) QCD matter in nuclei; and (4) Electroweak physics and the search for physics beyond the Standard Model. In this executive summary, we will briefly outline the outstanding physics questions in these areas and the suite of measurements that are available with an EIC to address these. The status of accelerator and detector designs is addressed at the end of the summary. Tables of golden measurements for each of the key science areas outlined are presented on page 12. In addition, each chapter in the report contains a comprehensive overview of the science topic addressed. Interested readers are encouraged to read these and the individual contributions for more details on the present status of EIC science.

  6. South Polar Skua breeding populations in the Ross Sea assessed from demonstrated relationship with Adélie Penguin numbers

    Science.gov (United States)

    Wilson, Deborah J.; Lyver, Phil O'B.; Greene, Terry C.; Whitehead, Amy L.; Dugger, Catherine; Karl, Brian J.; Barringer, James R. F.; McGarry, Roger; Pollard, Annie M.; Ainley, David G.

    2017-01-01

    In the Ross Sea region, most South Polar Skuas (Stercorarius maccormicki) nest near Adélie Penguin (Pygoscelis adeliae) colonies, preying and scavenging on fish, penguins, and other carrion. To derive a relationship to predict skua numbers from better-quantified penguin numbers, we used distance sampling to estimate breeding skua numbers within 1000 m of 5 penguin nesting locations (Cape Crozier, Cape Royds, and 3 Cape Bird locations) on Ross Island in 3 consecutive years. Estimated numbers of skua breeding pairs were highest at Cape Crozier (270,000 penguin pairs; 1099 and 1347 skua pairs in 2 respective years) and lowest at Cape Royds (3000 penguin pairs; 45 skua pairs). The log–log linear relationship (R2 = 0.98) between pairs of skuas and penguins was highly significant, and most historical estimates of skua and penguin numbers in the Ross Sea were within 95 % prediction intervals of the regression. Applying our regression model to current Adélie Penguin colony sizes at 23 western Ross Sea locations predicted that 4635 pairs of skuas now breed within 1000 m of penguin colonies in the Ross Island metapopulation (including Beaufort Island) and northern Victoria Land. We estimate, using published skua estimates for elsewhere in Antarctica, that the Ross Sea South Polar Skua population comprises ~50 % of the world total, although this may be an overestimate because of incomplete data elsewhere. To improve predictions and enable measurement of future skua population change, we recommend additional South Polar Skua surveys using consistent distance-sampling methods at penguin colonies of a range of sizes.

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

    Science.gov (United States)

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

    2014-01-01

    Context: The potential for research methods to affect wildlife is an increasing concern among both scientists and the public. This topic has a particular urgency for polar bears because additional research is needed to monitor and understand population responses to rapid loss of sea ice habitat.Aims: This study used data collected from polar bears sampled in the Alaska portion of the southern Beaufort Sea to investigate the potential for capture to adversely affect behaviour and vital rates. We evaluated the extent to which capture, collaring and handling may influence activity and movement days to weeks post-capture, and body mass, body condition, reproduction and survival over 6 months or more.Methods: We compared post-capture activity and movement rates, and relationships between prior capture history and body mass, body condition and reproductive success. We also summarised data on capture-related mortality.Key results: Individual-based estimates of activity and movement rates reached near-normal levels within 2–3 days and fully normal levels within 5 days post-capture. Models of activity and movement rates among all bears had poor fit, but suggested potential for prolonged, lower-level rate reductions. Repeated captures was not related to negative effects on body condition, reproduction or cub growth or survival. Capture-related mortality was substantially reduced after 1986, when immobilisation drugs were changed, with only 3 mortalities in 2517 captures from 1987–2013.Conclusions: Polar bears in the southern Beaufort Sea exhibited the greatest reductions in activity and movement rates 3.5 days post-capture. These shorter-term, post-capture effects do not appear to have translated into any long-term effects on body condition, reproduction, or cub survival. Additionally, collaring had no effect on polar bear recovery rates, body condition, reproduction or cub survival.Implications: This study provides empirical evidence that current capture

  8. TEMPERED FRACTIONAL CALCULUS

    Science.gov (United States)

    MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA

    2014-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series. PMID:26085690

  9. Tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sabzikar, Farzad, E-mail: sabzika2@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Meerschaert, Mark M., E-mail: mcubed@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Chen, Jinghua, E-mail: cjhdzdz@163.com [School of Sciences, Jimei University, Xiamen, Fujian, 361021 (China)

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  10. TEMPERED FRACTIONAL CALCULUS.

    Science.gov (United States)

    Meerschaert, Mark M; Sabzikar, Farzad; Chen, Jinghua

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  11. Scientific Research in Polar Seas – ERICON Science Perspective 2015-2030

    NARCIS (Netherlands)

    Wilmott, V.; Azzolini, R.; von Brandt, A.; Brinkhuis, H.; Camerlenghi, A.; Coakley, B.; De Santis, L.; Kristoffersen, Y.; Lembke-Jene, L.; Rebesco, M.; Thiede, J.; and other contributors, .

    2012-01-01

    Polar sciences are a modern branch of the natural sciences involving large groups of researchers, and sophisticated instrumentation contributing indispensable data for a better understanding of the polar regions and their impact on the global environment. The fact that a lot of the necessary

  12. Weakening of the stratospheric polar vortex by Arctic sea-ice loss

    National Research Council Canada - National Science Library

    Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

    2014-01-01

    ... of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

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

    Science.gov (United States)

    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 (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.

  14. Estimation of degree of sea ice ridging based on dual-polarized C-band SAR data

    Science.gov (United States)

    Gegiuc, Alexandru; Similä, Markku; Karvonen, Juha; Lensu, Mikko; Mäkynen, Marko; Vainio, Jouni

    2018-01-01

    For ship navigation in the Baltic Sea ice, parameters such as ice edge, ice concentration, ice thickness and degree of ridging are usually reported daily in manually prepared ice charts. These charts provide icebreakers with essential information for route optimization and fuel calculations. However, manual ice charting requires long analysis times, and detailed analysis of large areas (e.g. Arctic Ocean) is not feasible. Here, we propose a method for automatic estimation of the degree of ice ridging in the Baltic Sea region, based on RADARSAT-2 C-band dual-polarized (HH/HV channels) SAR texture features and sea ice concentration information extracted from Finnish ice charts. The SAR images were first segmented and then several texture features were extracted for each segment. Using the random forest method, we classified them into four classes of ridging intensity and compared them to the reference data extracted from the digitized ice charts. The overall agreement between the ice-chart-based degree of ice ridging and the automated results varied monthly, being 83, 63 and 81 % in January, February and March 2013, respectively. The correspondence between the degree of ice ridging reported in the ice charts and the actual ridge density was validated with data collected during a field campaign in March 2011. In principle the method can be applied to the seasonal sea ice regime in the Arctic Ocean.

  15. Estimation of degree of sea ice ridging based on dual-polarized C-band SAR data

    Directory of Open Access Journals (Sweden)

    A. Gegiuc

    2018-01-01

    Full Text Available For ship navigation in the Baltic Sea ice, parameters such as ice edge, ice concentration, ice thickness and degree of ridging are usually reported daily in manually prepared ice charts. These charts provide icebreakers with essential information for route optimization and fuel calculations. However, manual ice charting requires long analysis times, and detailed analysis of large areas (e.g. Arctic Ocean is not feasible. Here, we propose a method for automatic estimation of the degree of ice ridging in the Baltic Sea region, based on RADARSAT-2 C-band dual-polarized (HH/HV channels SAR texture features and sea ice concentration information extracted from Finnish ice charts. The SAR images were first segmented and then several texture features were extracted for each segment. Using the random forest method, we classified them into four classes of ridging intensity and compared them to the reference data extracted from the digitized ice charts. The overall agreement between the ice-chart-based degree of ice ridging and the automated results varied monthly, being 83, 63 and 81 % in January, February and March 2013, respectively. The correspondence between the degree of ice ridging reported in the ice charts and the actual ridge density was validated with data collected during a field campaign in March 2011. In principle the method can be applied to the seasonal sea ice regime in the Arctic Ocean.

  16. Assessment of RISAT-1 and Radarsat-2 for Sea Ice Observations from a Hybrid-Polarity Perspective

    Directory of Open Access Journals (Sweden)

    Martine M. Espeseth

    2017-10-01

    Full Text Available Utilizing several Synthetic Aperture Radar (SAR missions will provide a data set with higher temporal resolution. It is of great importance to understand the difference between various available sensors and polarization modes and to consider how to homogenize the data sets for a following combined analysis. In this study, a uniform and consistent analysis across different SAR missions is carried out. Three pairs of overlapping hybrid- and full-polarimetric C-band SAR scenes from the Radar Imaging Satellite-1 (RISAT-1 and Radarsat-2 satellites are used. The overlapping Radarsat-2 and RISAT-1 scenes are taken close in time, with a relatively similar incidence angle covering sea ice in the Fram Strait and Northeast Greenland in September 2015. The main objective of this study is to identify the similarities and dissimilarities between a simulated and a real hybrid-polarity (HP SAR system. The similarities and dissimilarities between the two sensors are evaluated using 13 HP features. The results indicate a similar separability between the sea ice types identified within the real HP system in RISAT-1 and the simulated HP system from Radarsat-2. The HP features that are sensitive to surface scattering and depolarization due to volume scattering showed great potential for separating various sea ice types. A subset of features (the second parameter in the Stokes vector, the ratio between the HP intensity coefficients, and the α s angle were affected by the non-circularity property of the transmitted wave in the simulated HP system across all the scene pairs. Overall, the best features, showing high separability between various sea ice types and which are invariant to the non-circularity property of the transmitted wave, are the intensity coefficients from the right-hand circular transmit and the linear horizontal receive channel and the right-hand circular on both the transmit and the receive channel, and the first parameter in the Stokes vector.

  17. Strong linkage of polar cod (Boreogadus saida) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses

    Science.gov (United States)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke

    2017-03-01

    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1-2 years) are often associated with the underside of sea ice. To evaluate the impact of changing Arctic sea ice habitats on polar cod, we examined the diet composition and quantified the contribution of ice algae-produced carbon (αIce) to the carbon budget of polar cod. Young polar cod were sampled in the ice-water interface layer in the central Arctic Ocean during late summer 2012. Diets and carbon sources of these fish were examined using 4 approaches: (1) stomach content analysis, (2) fatty acid (FA) analysis, (3) bulk nitrogen and carbon stable isotope analysis (BSIA) and (4) compound-specific stable isotope analysis (CSIA) of FAs. The ice-associated (sympagic) amphipod Apherusa glacialis dominated the stomach contents by mass, indicating a high importance of sympagic fauna in young polar cod diets. The biomass of food measured in stomachs implied constant feeding at daily rates of ∼1.2% body mass per fish, indicating the potential for positive growth. FA profiles of polar cod indicated that diatoms were the primary carbon source, indirectly obtained via amphipods and copepods. The αIce using bulk isotope data from muscle was estimated to be >90%. In comparison, αIce based on CSIA ranged from 34 to 65%, with the highest estimates from muscle and the lowest from liver tissue. Overall, our results indicate a strong dependency of polar cod on ice-algae produced carbon. This suggests that young polar cod may be particularly vulnerable to changes in the distribution and structure of sea ice habitats. Due to the ecological key role of polar cod, changes at the base of the sea ice-associated food web are likely to affect the higher trophic levels of high-Arctic ecosystems.

  18. 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

    Science.gov (United States)

    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.

  19. Sea ice and polar bear den ecology at Hopen Island, Svalbard

    National Research Council Canada - National Science Library

    A. E. Derocher; M. Andersen; Ø. Wiig; J. Aars; E. Hansen; M. Biuw

    2011-01-01

    The maternity denning of polar bears was studied at Hopen Island, Svalbard, Norway, using information collected by direct observation and live-capture of females and cubs during den emergence in spring of 1994 to 2008...

  20. Report to the annual joint meeting for management of polar bears in the southern Beaufort Sea

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Objectives of research conducted between 1 981 and the present were: 1. Determine the distribution timing and significance of maternal denning by polar bears in...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  3. Sea ice-associated diet change increases the levels of chlorinated and brominated contaminants in polar bears.

    Science.gov (United States)

    Mckinney, Melissa A; Peacock, Elizabeth; Letcher, Robert J

    2009-06-15

    Two global environmental issues, climate change and contamination by persistent organic pollutants, represent major concerns for arctic ecosystems. Yet, it is unclear how these two stressors interact in the Arctic. For instance, the influence of climate-associated changes in food web structure on exposure to pollutants within arctic ecosystems is presently unknown. Here, we report on recent changes in feeding ecology (1991-2007) in polar bears (Ursus maritimus) from the western Hudson Bay subpopulation that have resulted in increases in the tissue concentrations of several chlorinated and brominated contaminants. Differences in timing of the annual sea ice breakup explained a significant proportion of the diet variation among years. As expected from climate change predictions, this diet change was consistent with an increase in the consumed proportions of open water-associated seal species compared to ice-associated seal species in years of earlier sea ice breakup. Our results demonstrate that climate change is a modulating influence on contaminants in this polar bear subpopulation and may pose an additional and previously unidentified threat to northern ecosystems through altered exposures to contaminants.

  4. Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors, Version 3

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides daily sea ice motion vectors derived from a wide variety of sensors in both gridded and non-gridded (raw) files. For the gridded data, weekly...

  5. Phase equilibrium of North Sea oils with polar chemicals: Experiments and CPA modeling

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; Kontogeorgis, Georgios M.; von Solms, Nicolas

    2016-01-01

    This work consists of a combined experimental and modeling study for oil - MEG - water systems, of relevance to petroleum applications. We present new experimental liquid-liquid equilibrium data for the mutual solubility of two North Sea oils + MEG and North Sea oils + MEG + water systems...... in the temperature range 303.15-323.15 K and at atmospheric pressure. These new data are for North Sea oils which are substantially heavier and with higher aromatic/naphthenic content compared to previous studies. The new data compare favorably with previously reported measurements for other North Sea oils. The data...... have been successfully modeled using the Cubic- Plus-Association (CPA) equation of state (EoS) using a previously developed characterization method and new correlations for estimating binary interaction parameters between MEG-hydrocarbons and water-hydrocarbons. The results are in satisfactory...

  6. Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Sea Ice Concentrations

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides a near-real-time (NRT) map of sea ice concentrations for both the Northern and Southern Hemispheres. The near-real-time passive microwave...

  7. Aquarius L3 Polar-Gridded Weekly Sea Surface Salinity V005

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of weekly gridded Level-3 products of Aquarius L-band radiometer Sea Surface Salinity (SSS) retrievals from the Aquarius/Satélite de...

  8. Aquarius L3 Polar-Gridded Weekly Brightness Temperature and Sea Surface Salinity V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set consists of weekly gridded Level-3 products of Aquarius L-band radiometer brightness temperature (TB) observations and Sea Surface Salinity (SSS)...

  9. NASA IceBridge: Airborne surveys of the polar sea ice covers

    Science.gov (United States)

    Richter-Menge, J.; Farrell, S. L.

    2014-12-01

    The NASA Operation IceBridge (OIB) airborne sea ice surveys are designed to continue a valuable series of sea ice thickness measurements by bridging the gap between NASA's Ice, Cloud and Land Elevation Satellite (ICESat), which operated from 2003 to 2009, and ICESat-2, which is scheduled for launch in 2017. Initiated in 2009, OIB has conducted campaigns over the western Arctic Ocean (March/April) and Southern Oceans (October/November) on an annual basis. Primary OIB sensors being used for sea ice observations include the Airborne Topographic Mapper laser altimeter, the Digital Mapping System digital camera, a Ku-band radar altimeter, a frequency-modulated continuous-wave (FMCW) snow radar, and a KT-19 infrared radiation pyrometer. Data from the campaigns are available to the research community at: http://nsidc.org/data/icebridge/. This presentation will summarize the spatial and temporal extent of the campaigns and highlight key scientific accomplishments, which include: • Documented changes in the Arctic marine cryosphere since the dramatic sea ice loss of 2007 • Novel snow depth measurements over sea ice in the Arctic • Improved skill of April-to-September sea ice predictions via numerical ice/ocean models • Validation of satellite altimetry measurements (ICESat, CryoSat-2, and IceSat-2/MABEL)

  10. Stabilization of Global Temperature and Polar Sea-ice cover via seeding of Maritime Clouds

    Science.gov (United States)

    Chen, Jack; Gadian, Alan; Latham, John; Launder, Brian; Neukermans, Armand; Rasch, Phil; Salter, Stephen

    2010-05-01

    The marine cloud albedo enhancement (cloud whitening) geoengineering technique (Latham1990, 2002, Bower et al. 2006, Latham et al. 2008, Salter et al. 2008, Rasch et al. 2009) involves seeding maritime stratocumulus clouds with seawater droplets of size (at creation) around 1 micrometer, causing the droplet number concentration to increase within the clouds, thereby enhancing their albedo and possibly longevity. GCM modeling indicates that (subject to satisfactory resolution of specified scientific and technological problems) the technique could produce a globally averaged negative forcing of up to about -4W/m2, adequate to hold the Earth's average temperature constant as the atmospheric carbon dioxide concentration increases to twice the current value. This idea is being examined using GCM modeling, LES cloud modeling, technological development (practical and theoretical), and analysis of data from the recent, extensive VOCALS field study of marine stratocumulus clouds. We are also formulating plans for a possible limited-area field test of the technique. Recent general circulation model computations using a fully coupled ocean-atmosphere model indicate that increasing cloud reflectivity by seeding maritime boundary layer clouds may compensate for some effects on climate of increasing greenhouse gas concentrations. The chosen seeding strategy (one of many possible scenarios), when employed in an atmosphere where the CO2 concentration is doubled, can restore global averages of temperature, precipitation and polar sea-ice to present day values, but not simultaneously. The response varies nonlinearly with the extent of seeding, and geoengineering generates local changes to important climatic features. Our computations suggest that for the specimen cases examined there is no appreciable reduction of rainfall over land, as a consequence of seeding. This result is in agreement with one separate study but not another. Much further work is required to explain these

  11. TEMPERED FRACTIONAL CALCULUS

    OpenAIRE

    MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA

    2015-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly obs...

  12. NASA IceBridge: Scientific Insights from Airborne Surveys of the Polar Sea Ice Covers

    Science.gov (United States)

    Richter-Menge, J.; Farrell, S. L.

    2015-12-01

    The NASA Operation IceBridge (OIB) airborne sea ice surveys are designed to continue a valuable series of sea ice thickness measurements by bridging the gap between NASA's Ice, Cloud and Land Elevation Satellite (ICESat), which operated from 2003 to 2009, and ICESat-2, which is scheduled for launch in 2017. Initiated in 2009, OIB has conducted campaigns over the western Arctic Ocean (March/April) and Southern Oceans (October/November) on an annual basis when the thickness of sea ice cover is nearing its maximum. More recently, a series of Arctic surveys have also collected observations in the late summer, at the end of the melt season. The Airborne Topographic Mapper (ATM) laser altimeter is one of OIB's primary sensors, in combination with the Digital Mapping System digital camera, a Ku-band radar altimeter, a frequency-modulated continuous-wave (FMCW) snow radar, and a KT-19 infrared radiation pyrometer. Data from the campaigns are available to the research community at: http://nsidc.org/data/icebridge/. This presentation will summarize the spatial and temporal extent of the OIB campaigns and their complementary role in linking in situ and satellite measurements, advancing observations of sea ice processes across all length scales. Key scientific insights gained on the state of the sea ice cover will be highlighted, including snow depth, ice thickness, surface roughness and morphology, and melt pond evolution.

  13. Astrobiological Journeys to and from the South Polar Sea of Enceladus - Bidirectional Interactions with the Saturn Magmetosphere

    Science.gov (United States)

    Cooper, J. F.; Sittler, E. C.; Lipatov, A. S.; Sturner, S. J.

    2011-12-01

    The spectacularly cryovolcanic moon Enceladus is a major source of plasma for the Saturn magnetosphere via ionization of the ejected molecular species and ice grains. Field-aligned plasma flows from the Enceladus environment visibly impact the moon's magnetic footpoint in Saturn's polar auroral region, while water group and other ions from the moon emissions diffuse radially throughout the magnetosphere and may be the dominant source of oxygen for Titan's oxygen-poor upper atmosphere. But the moon-magnetosphere interaction is bidirectional in the sense that the moon surface is globally exposed to constant irradiation by the returning magnetospheric ions and by energetic electrons from the field-aligned and radially diffusing populations. The returning ion source operates both on global scales of the magnetosphere and locally for highly reactive species produced in the ejecta plume. All of these sources likely combine to produce a highly oxidized global surface layer. Since plasma electrons and ions are cooled by interaction with neutral gas and E-ring ice grains from Enceladus, the moon emissions have a governing effect on the seed populations of energetic particles that irradiate the surface. The proposed subsurface polar sea and transient crustal overturn in the south polar region could bring the polar surface oxidants into contact with hydrocarbons and ammonia to make oxidation product gases contributing to the cryovolcanic jets, a process first proposed by Cooper et al. (Plan. Sp. Sci., 2009). As has been previously suggested for Europa, the oxidants could contribute to enhanced astrobiological potential of Enceladus, perhaps even higher than for Europa where organic hydrocarbons have not yet been directly detected. Unlike Europa, Enceladus shows no sign of an oxygen-dominated exosphere that could otherwise be indicative of extreme surface and interior oxidation inhibiting the detectable survival and evolution of complex organics.

  14. Astrobiological Journeys to and from the South Polar Sea of Enceladus - Bidirectional Interactions with the Saturn Magnetosphere

    Science.gov (United States)

    Cooper, John F.; Sittler, Edward C.; Lipatov, Alexander S.; Sturner, Steven J.

    2012-01-01

    The spectacularly cryovolcanic moon Enceladus is a major source of plasma for the Saturn magnetosphere via ionization of the ejected molecular species and ice grains. Field-aligned plasma flows from the Enceladus environment visibly impact the moon's magnetic footpoint in Saturn's polar auroral region, while water group and other ions from the moon emissions diffuse radially throughout the magnetosphere and may be the dominant source of oxygen for Titan's oxygen-poor upper atmosphere. But the moon-magnetosphere interaction is bidirectional in the sense that the moon surface is globally exposed to constant irradiation by the returning magnetospheric ions and by energetic electrons from the field-aligned and radially diffusing populations. The returning ion source operates both on global scales of the magnetosphere and locally for highly reactive species produced in the ejecta plume. All of these sources likely combine to produce a highly oxidized global surface layer. Since plasma electrons and ions are cooled by interaction with neutral gas and E-ring ice grains from Enceladus, the moon emissions have a governing effect on the seed populations of energetic particles that irradiate the surface. The proposed subsurface polar sea and transient crustal overturn in the south polar region could bring the polar surface oxidants into contact with hydrocarbons and ammonia to make oxidation product gases contributing to the cryovolcanic jets, a process first proposed by Cooper et al. (Plan. Sp. Sci., 2009). As has been previously suggested for Europa, the 'oxidants could contribute to enhanced astrobiological potential of Enceladus, perhaps even higher than for Europa where organic hydrocarbons have not yet been directly detected. Unlike Europa, Enceladus shows no sign of an oxygen-dominated exosphere that could otherwise be indicative of extreme surface and interior oxidation inhibiting the detectable survival and evolution of complex organics.

  15. Gluons and the quark sea at high energies : distributions, polarization, tomography

    NARCIS (Netherlands)

    Boer, D.; Diehl, M.; Milner, R.; Venugopalan, R.; Vogelsang, W.; Accardi, A.; Aschenauer, E.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M. A. C.; Li, Y.; Marciano, W. J.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Abeyratne, S.; Ahmed, S.; Aidala, C.; Alekhin, S.; Anselmino, M.; Avakian, H.; Bacchetta, A.; Bartels, J.; H., BC; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Beuf, G.; Blumlein, J.; Blaskiewicz, M .; Bogacz, A.; Brodsky, S. J.; Burton, T.; Calaga, R.; Chang, X.; Cherednikov, I. O.; Chevtsov, P.; Chirilli, G. A.; Atti, C. Ciofi degli; Cloet, I. C.; Cooper-Sarkar, A.; Debbe, R.; Derbenev, Ya; Deshpande, A.; Dominguez, F.; Dumitru, A.; Dupre, R.; Erdelyi, B.; Faroughy, C.; Fazio, S.; Fedotov, A.; Forshaw, J. R.; Geraud, R.; Gallmeister, K.; Gamberg, L.; Gao, J. -H.; Gassner, D.; Gelis, F.; Gilfoyle, G. P.; Goldstein, G.; Golec-Biernat, K.; Goncalves, V. P.; Gonderinger, M.; Guzzi, M.; Hagler, P.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Horn, T.; Horowitz, W. A.; Huang, M.; Hutton, A.; Jager, B.; Jackson, W.; Jain, A.; Johnson, E. C.; Kang, Z. -B.; Kaptari, L. P.; Kayran, D.; Kewisch, J.; Koike, Y.; Kondratenko, A.; Kopeliovich, B. Z.; Kovchegov, Y. V.; Krafft, G.; Kroll, P.; Kumano, S.; Kumericki, K.; Lappi, T.; Lautenschlager, T.; Li, R.; Liang, Z. -T.; Litvinenko, V. N.; Liuti, S.; Luo, Y.; Muller, D.; Mahler, G.; Majumder, A.; Manikonda, S.; Marhauser, F.; McIntyre, G.; Meskauskas, M.; Meng, W.; Metz, A.; Mezzetti, C. B.; Miller, G. A.; Minty, M.; Moch, S. -O.; Morozov, V.; Mosel, U.; Motyka, L.; Moutarde, H.; Mulders, P. J.; Musch, B.; Nadel-Turonski, P.; Nadolsky, P.; Olness, F.; Ostrumov, P. N.; Parker, B.; Pasquini, B.; Passek-Kumericki, K.; Pikin, A.; Pilat, F.; Pire, B.; Pirner, H.; Pisano, C.; Pozdeyev, E.; Prokudin, A.; Ptitsyn, V.; Qian, X.; Qiu, J. -W.; Radici, M.; Radyushkin, A.; Rao, T.; Rimmer, R.; Ringer, F.; Riordan, S.; Rogers, T.; Rojo, J.; Roser, T.; Sandapen, R.; Sassot, R.; Satogata, T.; Sayed, H.; Schafer, A.; Schnell, G.; Schweitzer, P.; Sheehy, B.; Skaritka, J.; Soyez, G.; Spata, M.; Spiesberger, H.; Stasto, A. M.; Stefanis, N. G.; Strikman, M.; Sullivan, M.; Szymanowski, L.; Tanaka, K.; Taneja, S.; Tepikian, S.; Terzic, B.; Than, Y.; Toll, T.; Trbojevic, D.; Tsentalovich, E.; Tsoupas, N.; Tuchin, K.; Tuozzolo, J.; Ullrich, T.; Vossen, A.; Wallon, S.; Wang, G.; Wang, H.; Wang, X. -N.; Webb, S.; Weiss, C.; Wu, Q.; Xiao, B. -W.; Xu, W.; Yunn, B.; Zelenski, A.; Zhang, Y.; Zhou, J.; Zurita, P.

    2011-01-01

    This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that

  16. Past, present and impendent hydroelastic challenges in the polar and subpolar seas.

    Science.gov (United States)

    Squire, Vernon A

    2011-07-28

    Current and emergent advances are examined on the topic of hydroelasticity theory applied to natural sea ice responding to the action of ocean surface waves and swell, with attention focused on methods that portray sea ice more faithfully as opposed to those that oversimplify interactions with a poor imitation of reality. A succession of authors have confronted and solved by various means the demanding applied mathematics associated with ocean waves (i) entering a vast sea-ice plate, (ii) travelling between plates of different thickness, (iii) impinging on a pressure ridge, (iv) affecting a single ice floe with arbitrarily specified physical and material properties, and (v) many such features or mixtures thereof. The next step is to embed simplified versions of these developments in an oceanic general circulation model for forecasting purposes. While targeted on specific sea-ice situations, many of the reported results are equally applicable to the interaction of waves with very large floating structures, such as pontoons, floating airports and mobile offshore bases.

  17. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the USCGC POLAR SEA in the North Greenland Sea from 1992-07-15 to 1992-08-14 (NODC Accession 0115687)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115687 includes biological, chemical, discrete sample, physical and profile data collected from USCGC POLAR SEA in the North Greenland Sea from...

  18. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the USCGC POLAR SEA in the North Greenland Sea from 1993-07-18 to 1993-08-20 (NODC Accession 0114447)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0114447 includes biological, chemical, discrete sample, physical and profile data collected from USCGC POLAR SEA in the North Greenland Sea from...

  19. Communicating polar science to the general public: sharing the social media experience of @OceanSeaIceNPI

    Science.gov (United States)

    Rösel, Anja; Pavlov, Alexey K.; Granskog, Mats A.; Gerland, Sebastian; Meyer, Amelie; Hudson, Stephen R.; King, Jennifer; Itkin, Polona; Cohen, Lana; Dodd, Paul; de Steur, Laura

    2016-04-01

    The findings of climate science need to be communicated to the general public. Researchers are encouraged to do so by journalists, policy-makers and funding agencies and many of us want to become better science communicators. But how can we do this at the lab or small research group level without specifically allocated resources in terms of funds and communication officers? And how do we sustain communication on a regular basis and not just during the limited lifetime of a specific project? One of the solutions is to use the emerging platform of social media, which has become a powerful and inexpensive tool for communicating science to different target audiences. Many research institutions and individual researchers are already advanced users of social media, but small research groups and labs remain underrepresented. The group of oceanographers, sea ice and atmospheric scientists at the Norwegian Polar Institute (@OceanSeaIceNPI( will share our experiences developing and maintaining researcher-driven outreach for over a year through Instagram, Twitter and Facebook. We will present our solutions to some of the practical considerations such as identifying key target groups, defining the framework for sharing responsibilities and interactions within the research group, and choosing an up-to-date and appropriate social medium. By sharing this information, we aim to inspire and assist other research groups and labs in conducting their own effective science communication.

  20. Serial tempering without exchange.

    Science.gov (United States)

    Nymeyer, Hugh

    2010-09-21

    Serial tempering is a computational method that turns the temperature T (or more generally any independent λ parameter) into a dynamical variable. It is shown that, under conditions for which this variable is fast, serial tempering is equivalent to the umbrella sampling method with a single effective potential. This equivalence is demonstrated using both a small one-dimensional system and a small solvated peptide. The suggestion is then made to replace the serial tempering protocol with the equivalent umbrella sampling calculation. This approach, serial tempering without exchange (STeWiE), has the same performance as serial tempering in the limit that exchanges are frequent, is simpler to implement, and has fewer adjustable parameters than conventional serial tempering. The equivalence of serial tempering and STeWiE also provides a convenient route for estimating and optimizing the performance of serial tempering simulations and other generalized-ensemble methods.

  1. Detrital zircons of deep-sea sediments of the Arctic ocean - key to the understanding of High Polar Arctic tectonics

    Science.gov (United States)

    Shokalsky, S.; Morozov, A.; Petrov, O.; Belyatsky, B.; Rekant, P.; Shevchenko, S.; Sergeev, S.

    2012-04-01

    appreciably different for Polar sample (200-450 Ma) and Geophysicists Spur (200, 300, 400-600 Ma). It is known, that formation of modern deep-sea sediments takes place mainly due to fluvial discharge (ca 90%), erosion of oceanic bedrocks and coastal beaches. Wind-borne component and extraterraneous dust are not significant (<1%). Transportation of continental material by icebergs (ice-rafted debris) is added to these sources in polar areas. Well-known Permian-Triassic sandstones of Arctic coast (including polar islands) are defined by the presence of Grenvillian age zircons - Canadian Arctic, Alaska, Greenland (Miller et al., 2006), while Jurassic-Cretaceous sandstones of the South Anjui Zone, Chukotka and New Siberian Islands of Russian Arctic (Miller et al., 2008) have clastic zircon with ages very similar to the obtained by us for deep-sea sediments. We suppose that modern deep-sea sediments were formed either due to ablation of these sandstones with distal transportation of detritus (highly unlikely), or due to weathering of similar rock of oceanic highs of Lomonosov Ridge. The last is more realistic because the similarity of the Lomonosov Ridge and north-east continental Arctic is proved by geophysical data (Jokat et al., 1992).

  2. Collar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land

    Science.gov (United States)

    Olson, Jay W; Rode, Karyn D.; Eggett, Dennis L.; Smith, T.S.; Wilson, R. R.; Durner, George M.; Fischbach, Anthony; Atwood, Todd C.; Douglas, David

    2017-01-01

    In response to a changing climate, many species alter habitat use. Polar bears Ursus maritimus in the southern Beaufort Sea have increasingly used land for maternal denning. To aid in detecting denning behavior, we developed an objective method to identify polar bear denning events using temperature sensor data collected by satellite-linked transmitters deployed on adult females between 1985 and 2013. We then applied this method to determine whether southern Beaufort Sea polar bears have continued to increase land denning with recent sea-ice loss and examined whether sea-ice conditions affect the distribution of dens between pack-ice and coastal substrates. Because land use in summer and autumn has also increased, we examined potential associations between summering substrate and denning substrate. Statistical process control methods applied to temperature-sensor data identified denning events with 94.5% accuracy in comparison to direct observations (n = 73) and 95.7% accuracy relative to subjective classifications based on temperature, location, and activity sensor data (n = 116). We found an increase in land-based denning during the study period. The frequency of land denning was directly related to the distance that sea ice retreated from the coast. Among females that denned, all 14 that summered on land subsequently denned there, whereas 29% of the 69 bears summering on ice denned on land. These results suggest that denning on land may continue to increase with further loss of sea ice. While the effects that den substrate have on nutrition, energetics, and reproduction are unclear, more polar bears denning onshore will likely increase human-bear interactions.

  3. On the classification of mixed floating pollutants on the Yellow Sea of China by using a quad-polarized SAR image

    Science.gov (United States)

    Wang, Xiaochen; Shao, Yun; Tian, Wei; Li, Kun

    2017-09-01

    This study explored different methodologies using a C-band RADARSAT-2 quad-polarized Synthetic Aperture Radar (SAR) image located over China's Yellow Sea to investigate polarization decomposition parameters for identifying mixed floating pollutants from a complex ocean background. It was found that solitary polarization decomposition did not meet the demand for detecting and classifying multiple floating pollutants, even after applying a polarized SAR image. Furthermore, considering that Yamaguchi decomposition is sensitive to vegetation and the algal variety Enteromorpha prolifera, while H/A/alpha decomposition is sensitive to oil spills, a combination of parameters which was deduced from these two decompositions was proposed for marine environmental monitoring of mixed floating sea surface pollutants. A combination of volume scattering, surface scattering, and scattering entropy was the best indicator for classifying mixed floating pollutants from a complex ocean background. The Kappa coefficients for Enteromorpha prolifera and oil spills were 0.7514 and 0.8470, respectively, evidence that the composite polarized parameters based on quad-polarized SAR imagery proposed in this research is an effective monitoring method for complex marine pollution.

  4. Trophic relations of capelin Mallotus villosus and polar cod Boreogadus saida in the Barents Sea as a factor of impact on the ecosystem

    Science.gov (United States)

    Orlova, Emma L.; Dolgov, Andrey V.; Rudneva, Galina B.; Oganin, Ivan A.; Konstantinova, Ludmila L.

    2009-10-01

    The purpose of the study is to assess the role of trophic relations of the dominant pelagic fishes capelin and polar cod in the Barents Sea with regard to distribution and accessibility as prey for the Atlantic cod in warm years (2004-2005). Unlike in the previous period, during these warm years a dramatic increase of the polar cod population resulted in a northwards expansion of the feeding grounds where overlapping of polar cod and capelin concentrations was observed. This caused an increased competition for copepods, which are the main food item for young fish. In the areas dominated by polar cod the shortage of copepods forced immature capelin to switch to the chaetognath Sagitta, which affected their fatness negatively. During the warm years the feeding grounds of Atlantic cod also expanded, to a large degree caused by the shortage of their main food, the capelin. In 2004-2005 the cod formed feeding concentrations in the north and northeast Barents Sea where they fed on the capelin. In this area the consumption of polar cod by cod increased, and in some local areas the polar cod practically replaced the capelin in the diet of cod. In general polar cod in the diet of Atlantic cod were more important in the northern than in the southern part of the Barents Sea. The fatness of cod was extremely low during the whole spring-summer period (until August), and after the feeding period the fatness index of the Atlantic cod became lower than the average long-term autumn value.

  5. Implications caused by SARex on the implementation of the IMO polar code on survival at sea

    Science.gov (United States)

    Solberg, K. E.

    2017-12-01

    The International Code for Ships Operating in Polar waters goes into effect on 01 January 2018 for all ships. This puts additional strain on vessel owners and operators as they will have to comply with an additional set of requirements. This includes the functional requirement of a minimum of 5 days survival time. The SARex exercise has elaborated on the issue of survival in close cooperation with the different stakeholders associated with the marine industry. Being an objective third party is important when organizing and executing these activities as all of the stakeholders has different agendas and priorities. Developing sustainable solutions is a balancing act, incorporating economic and political aspects as well as technology and requires a mutual common understanding of the mechanism involved.

  6. Experimental study of dual polarized radar return from the sea surface

    Science.gov (United States)

    Ermakov, S. A.; Kapustin, I. A.; Lavrova, O. Yu.; Molkov, A. A.; Sergievskaya, I. A.; Shomina, O. V.

    2017-10-01

    Dual-polarized microwave radars are of particular interest nowadays as perspective tool of ocean remote sensing. Microwave radar backscattering at moderate and large incidence angles according to conventional models is determined by resonance (Bragg) surface waves typically of cm-scale wavelength range. Some recent experiments have indicated, however, that an additional, non Bragg component (NBC) contributes to the radar return. The latter is considered to occur due to wave breaking. At present our understanding of the nature of different components of radar return is still poor. This paper presents results of field experiment using an X-/C-/S-band Doppler radar operating at HH- and VVpolarizations. The intensity and radar Doppler shifts for Bragg and non Bragg components are retrieved from measurements of VV and HH radar returns. Analysis of a ratio of VV and HH radar backscatter - polarization ratio (PR) has demonstrated a significant role of a non Bragg component. NBC contributes significantly to the total radar backscatter, in particular, at moderate incidence angles (about 50-70 deg.) it is 2-3 times smaller than VV Bragg component and several times larger that HH Bragg component. Both NBC and BC depend on azimuth angle, being minimal for cross wind direction, but NBC is more isotropic than BC. It is obtained that velocities of scatterers retrieved from radar Doppler shifts are different for Bragg waves and for non Bragg component; NBC structures are "faster" than Bragg waves particularly for upwind radar observations. Bragg components propagate approximately with phase velocities of linear gravity-capillary waves (when accounting for wind drift). Velocities of NBC scatterers depend on radar band, being the largest for S-band and the smallest at X-band, this means that different structures on the water surface are responsible for non Bragg scattering in a given radar band.

  7. Sea ice-associated decline in body condition leads to increased concentrations of lipophilic pollutants in polar bears (Ursus maritimus) from Svalbard, Norway.

    Science.gov (United States)

    Tartu, Sabrina; Bourgeon, Sophie; Aars, Jon; Andersen, Magnus; Polder, Anuschka; Thiemann, Gregory W; Welker, Jeffrey M; Routti, Heli

    2017-01-15

    Global climate changes are magnified in the Arctic and are having an especially dramatic effect on the spatial and temporal distribution and the thickness traits of sea ice. Decline of Arctic sea ice may lead to qualitative and/or quantitative changes in diet and reduced body condition (i.e. adipose tissue stores) of ice-associated apex predators such as polar bears (Ursus maritimus). This may further affect their tissue concentrations of lipophilic pollutants. We determined how variations in adipose tissue stores associated to both breeding status and spatial changes in sea ice conditions and diet influence concentrations and biotransformation of lipophilic persistent organic pollutants (POPs). We collected 112 blood and fat samples from female polar bears (Ursus maritimus) of different breeding status (alone, with cubs of the year, or with yearlings) during two seasons (April and September) in 2012 and 2013 at three locations of Svalbard, Norway, with contrasted sea ice conditions. We inferred diet from nitrogen and carbon stable isotope ratios in red blood cells and fatty acid composition in adipose tissue. Relative to diet, body condition, which was negatively related to sea ice extent at both temporal and spatial scales, was the most important predictor for concentrations of POPs in plasma and fat, whereas diet showed a minor influence. Additionally, fatter females were more efficient at biotransforming PCBs than were leaner ones. Breeding status influenced the concentrations of less lipophilic compounds such as β-hexachlorocyclohexane, which were lower in females with yearlings, probably due to excretion into milk and subsequent offloading to young. In conclusion, our results indicate that declining sea ice indirectly leads to increased concentrations of lipophilic pollutants in polar bears mediated through reduced feeding opportunities and declining body condition rather than changes in diet composition. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Demographic and temporal variations in immunity and condition of polar bears (Ursus maritimus) from the southern Beaufort Sea

    Science.gov (United States)

    Neuman-Lee, Lorin; Terletzky, Patricia; Atwood, Todd C.; Gese, Eric; Smith, Geoffrey; Greenfield, Sydney; Pettit, John; French, Susannah

    2017-01-01

    Assessing the health and condition of animals in their natural environment can be problematic. Many physiological metrics, including immunity, are highly influenced by specific context and recent events to which researchers may be unaware. Thus, using a multifaceted physiological approach and a context-specific analysis encompassing multiple time scales can be highly informative. Ecoimmunological tools in particular can provide important indications to the health of animals in the wild. We collected blood and hair samples from free-ranging polar bears (Ursus maritimus) in the southern Beaufort Sea and examined the influence of sex, age, and reproductive status on metrics of immunity, stress, and body condition during 2013–2015. We examined metrics of innate immunity (bactericidal ability and lysis) and stress (hair cortisol, reactive oxygen species, and oxidative barrier), in relation to indices of body condition considered to be short term (urea to creatinine ratio; UC ratio) and long term (storage energy and body mass index). We found the factors of sex, age, and reproductive status of the bear were critical for interpreting different physiological metrics. Additionally, the metrics of body condition were important predictors for stress indicators. Finally, many of these metrics differed between years, illustrating the need to examine populations on a longer time scale. Taken together, this study demonstrates the complex relationship between multiple facets of physiology and how interpretation requires us to examine individuals within a specific context.

  9. Connections Between the Spring Breakup of the Southern Hemisphere Polar Vortex, Stationary Waves, and Air-sea Roughness

    Science.gov (United States)

    Garfinkel, Chaim I.; Oman, Luke David; Barnes, Elizabeth A.; Waugh, Darryn W.; Hurwitz, Margaret H.; Molod, Andrea M.

    2013-01-01

    A robust connection between the drag on surface-layer winds and the stratospheric circulation is demonstrated in NASA's Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Specifically, an updated parameterization of roughness at the air-sea interface, in which surface roughness is increased for moderate wind speeds (4ms to 20ms), leads to a decrease in model biases in Southern Hemispheric ozone, polar cap temperature, stationary wave heat flux, and springtime vortex breakup. A dynamical mechanism is proposed whereby increased surface roughness leads to improved stationary waves. Increased surface roughness leads to anomalous eddy momentum flux convergence primarily in the Indian Ocean sector (where eddies are strongest climatologically) in September and October. The localization of the eddy momentum flux convergence anomaly in the Indian Ocean sector leads to a zonally asymmetric reduction in zonal wind and, by geostrophy, to a wavenumber-1 stationary wave pattern. This tropospheric stationary wave pattern leads to enhanced upwards wave activity entering the stratosphere. The net effect is an improved Southern Hemisphere vortex: the vortex breaks up earlier in spring (i.e., the spring late-breakup bias is partially ameliorated) yet is no weaker in mid-winter. More than half of the stratospheric biases appear to be related to the surface wind speed biases. As many other chemistry climate models use a similar scheme for their surface layer momentum exchange and have similar biases in the stratosphere, we expect that results from GEOSCCM may be relevant for other climate models.

  10. An Efficient Non-iterative Bulk Parametrization of Surface Fluxes for Stable Atmospheric Conditions Over Polar Sea-Ice

    Science.gov (United States)

    Gryanik, Vladimir M.; Lüpkes, Christof

    2017-10-01

    In climate and weather prediction models the near-surface turbulent fluxes of heat and momentum and related transfer coefficients are usually parametrized on the basis of Monin-Obukhov similarity theory (MOST). To avoid iteration, required for the numerical solution of the MOST equations, many models apply parametrizations of the transfer coefficients based on an approach relating these coefficients to the bulk Richardson number Rib . However, the parametrizations that are presently used in most climate models are valid only for weaker stability and larger surface roughnesses than those documented during the Surface Heat Budget of the Arctic Ocean campaign (SHEBA). The latter delivered a well-accepted set of turbulence data in the stable surface layer over polar sea-ice. Using stability functions based on the SHEBA data, we solve the MOST equations applying a new semi-analytic approach that results in transfer coefficients as a function of Rib and roughness lengths for momentum and heat. It is shown that the new coefficients reproduce the coefficients obtained by the numerical iterative method with a good accuracy in the most relevant range of stability and roughness lengths. For small Rib , the new bulk transfer coefficients are similar to the traditional coefficients, but for large Rib they are much smaller than currently used coefficients. Finally, a possible adjustment of the latter and the implementation of the new proposed parametrizations in models are discussed.

  11. Antioxidant responses in the polar marine sea-ice amphipod Gammarus wilkitzkii to natural and experimentally increased UV levels

    Energy Technology Data Exchange (ETDEWEB)

    Krapp, Rupert H., E-mail: rkrapp@ipoe.uni-kiel.de [University of Kiel, Institute for Polar Ecology, Wischhofstr. 1-3, Building 12, 24148 Kiel (Germany); University Center in Svalbard, Postbox 156, 9171 Longyearbyen (Norway); Bassinet, Thievery [International Research Institute of Stavanger (IRIS), Mekjarvik 12, N-4070 Randaberg (Norway); Berge, Jorgen [University Center in Svalbard, Postbox 156, 9171 Longyearbyen (Norway); Pampanin, Daniela M. [International Research Institute of Stavanger (IRIS), Mekjarvik 12, N-4070 Randaberg (Norway); Camus, Lionel [Akvaplan-niva a/s, Polar Environmental Centre, N-9296 Tromso (Norway)

    2009-08-13

    Polar marine surface waters are characterized by high levels of dissolved oxygen, seasonally intense UV irradiance and high levels of dissolved organic carbon. Therefore, the Arctic sea-ice habitat is regarded as a strongly pro-oxidant environment, even though its significant ice cover protects the ice-associated (=sympagic) fauna from direct irradiation to a large extent. In order to investigate the level of resistance to oxyradical stress, we sampled the sympagic amphipod species Gammarus wilkitzkii during both winter and summer conditions, as well as exposed specimens to simulated levels of near-natural and elevated levels of UV irradiation. Results showed that this amphipod species possessed a much stronger antioxidant capacity during summer than during winter. Also, the experimental UV exposure showed a depletion in antioxidant defences, indicating a negative effect of UV exposure on the total oxyradical scavenging capacity. Another sympagic organism, Onisimus nanseni, was sampled during summer conditions. When compared to G. wilkitzkii, the species showed even higher antioxidant scavenging capacity.

  12. The Need for Temperance

    Directory of Open Access Journals (Sweden)

    Karl Inge Tangen

    2015-11-01

    Full Text Available This article explores how temperance as a virtue relates to organizational leadership. The study begins with a short survey of classical Greek and Christian notions of temperance before proceeding to ex-plore temperance in relation to self-leadership, visionary and strategic leadership, and relational lead-ership. The final part of the article offers reflections on how temperance might be cultivated from a theological perspective. Temperance is understood not only as sound thinking but also as embodied self-control and active patience. On the level of self-leadership, it is argued that temperance enables the leader to establish forms of integrity that protect the leader’s self from chaos and destruction. Moreover, temperance may also nurture focused visionary leadership that accepts ethical limits and has an eye to the common good. The study also suggests that organizations should cultivate a culture of strategic discipline that is capable of realizing such visions. On the interpersonal level, temperance is viewed as critical in terms of enabling leaders to treat co-workers with respect and wisdom and han-dle conflict with consideration. Finally, is argued that that the cultivation of temperance is not a one-way street from the inside to the outside or a subordination of feelings to reason but rather a very complex process that includes interpersonal humility, finds vision in an encounter with the good, and yet remains a personal responsibility.

  13. Temperature profile and water depth data from BT and XBT casts in the Atlantic Ocean from USCGC POLAR SEA from 14 December 1983 to 06 May 1984 (NODC Accession 8600108)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USCGC POLAR SEA in the Atlantic Ocean. Data were collected from 14 December...

  14. Marine toxic substance and other data from grab casts in the Bering Sea from the USCGC POLAR STAR as part of Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 29 April 1980 to 28 June 1980 (NODC Accession 8100551)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Marine toxic substance and other data were collected from grab casts in the Bering Sea from the USCGC POLAR STAR from 29 April 1980 to 28 June 1980. Data were...

  15. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE and NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 08 April 1997 to 05 May 1997 (NODC Accession 0000897)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  16. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE and NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 10 November 1997 to 12 December 1997 (NODC Accession 0000898)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  17. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE AND NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 12 January 1997 to 09 February 1997 (NODC Accession 0000896)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  18. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE in the Ross Sea and Southern Oceans from 06 September 1996 to 12 September 1996 (NODC Accession 0000890)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from POLAR DUKE. Data were collected from 06 September...

  19. Non-polar organic compounds in marine aerosols over the northern South China Sea: Influence of continental outflow.

    Science.gov (United States)

    Zhao, Yan; Zhang, Yingyi; Fu, Pingqing; Ho, Steven Sai Hang; Ho, Kin Fai; Liu, Fobang; Zou, Shichun; Wang, Shan; Lai, Senchao

    2016-06-01

    Filter samples of total suspended particle (TSP) collected during a cruise campaign over the northern South China Sea (SCS) from September to October 2013 were analyzed for non-polar organic compounds (NPOCs) as well as organic carbon (OC), elemental carbon (EC) and water-soluble ions. A total of 115 NPOCs species in groups of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), iso-/antiso-alkanes, hopanes, steranes, methylalkanes, branched alkanes, cycloalkanes, alkenes and phthalates were detected. The characteristics of NPOCs in marine TSP samples were investigated to understand the sources from the Asian continent and other regions. The concentrations of total NPOCs ranged from 19.8 to 288.2 ng/m(3) with an average of 87.9 ng/m(3), which accounted for 0.8-1.7% (average 1.0%) of organic matter (OM). n-Alkanes was the predominant group, accounting for 43.1-79.5%, followed by PAHs (5.5-44.4%) and hopanes (1.6-11.4%). We found that primary combustion (biomass burning/fossil fuel combustion) was the dominant source for the majority of NPOCs (89.1%). Biomass burning in southern/southeastern China via long-range transport was proposed to be a major contributor of NPOCs in marine aerosols over the northern SCS, suggested by the significant correlations between nss-K(+) and NPOCs groups as well as the analysis of air mass back-trajectory and fire spots. For the samples with strong continental influence, the strong enhancement in concentrations of n-alkanes, PAHs, hopanes and steranes were attributed to fossil fuel (coal/petroleum) combustion. In addition, terrestrial plants waxes were another contributor to NPOCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay.

    Science.gov (United States)

    Lunn, Nicholas J; Servanty, Sabrina; Regehr, Eric V; Converse, Sarah J; Richardson, Evan; Stirling, Ian

    2016-07-01

    Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture-recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993-1411) in 1987 to 806 (95% BCI = 653-984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001-2010 = 1.02, 95% BCI = 0.98-1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00-1.05) and 0.97 (95% BCI = 0.92-1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations. © 2016 by the Ecological Society of

  1. The Polar Front mean state and variability in the Barents Sea in a context of climate change : a satellite altimetry approach.

    Science.gov (United States)

    Oziel, Laurent; Provost, Christine; Gascard, Jean-Claude

    2014-05-01

    The Barents Sea (BS) is a sub-arctic shallow continental shelf sea where drastic changes are currently happening. BS a key region to study present and future Arctic climate change. Indeed, BS is a pathway area where the warm and saline Atlantic Waters (AW) meet the colder and fresher Arctic Waters (ArW) and locally formed waters (BSW) are providing Intermediate Arctic water and participate in Arctic ventilation (e.g. Schauer et al. 2002). The Polar Front separating the AW and ArW water masses shows a large seasonal and interannual variability which is of importance for physical and biological processes (Loeng, 1991). We study the Barents Sea Polar Front (BSPF) mean characteristics and variations during the 1993-2009 period using in-situ, satellite altimetry and model outputs. BSPF is a double front made of two branches delimitating a mixing area where BSW are formed. We show that this satellite altimetry product adapted for the Arctic (Prandi et al., 2013) is an appropriate tool for examining BSPF branches and their variations.

  2. Coastal Temperate Rainforest Symposium

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The North Pacific LCC is helping sponsor the April 2012 science symposium - Coastal Temperate Rainforests: Integrating Communities, Climate Science, and Resource...

  3. Craniometric characteristics of polar bear skulls from two periods with contrasting levels of industrial pollution and sea ice extent

    DEFF Research Database (Denmark)

    Pertoldi, C.; Sonne, C.; Dietz, R.

    2009-01-01

    A morphometric study was conducted on six skull traits and seven teeth traits of 282 polar bear Ursus maritimus skulls sampled in East Greenland from 1892 to 2002, the polar bear material originated from two distinct periods: one period covering 1892-1939 and the other from 1961-2002. The first p...

  4. Retrieving simulated volcanic, desert dust and sea-salt particle properties from two/three-component particle mixtures using UV-VIS polarization lidar and T matrix

    Directory of Open Access Journals (Sweden)

    G. David

    2013-07-01

    Full Text Available During transport by advection, atmospheric nonspherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex vertical layering in the case of a two/three-component particle external mixtures. This methodology relies on an analysis of the spectral and polarization properties of the light backscattered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization lidar experiment with T-matrix numerical simulations and air mass back trajectories. The Lyon UV-VIS polarization lidar is used to efficiently partition the particle mixture into its nonspherical components, while the T-matrix method is used for simulating the backscattering and depolarization properties of nonspherical volcanic ash, desert dust and sea-salt particles. It is shown that the particle mixtures' depolarization ratio δ p differs from the nonspherical particles' depolarization ratio δns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspherical component can be retrieved in a two-component external mixture. For three-component mixtures, the spectral properties of light must in addition be exploited by using a dual-wavelength polarization lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formalism. Applications of this new methodology are then demonstrated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulfate particles (case of a two-component mixture and to the mixing of dust with sea-salt and water-soluble particles

  5. Iron in sea ice: Review and new insights

    Directory of Open Access Journals (Sweden)

    D. Lannuzel

    2016-10-01

    Full Text Available Abstract The discovery that melting sea ice can fertilize iron (Fe-depleted polar waters has recently fostered trace metal research efforts in sea ice. The aim of this review is to summarize and synthesize the current understanding of Fe biogeochemistry in sea ice. To do so, we compiled available data on particulate, dissolved, and total dissolvable Fe (PFe, DFe and TDFe, respectively from sea-ice studies from both polar regions and from sub-Arctic and northern Hemisphere temperate areas. Data analysis focused on a circum-Antarctic Fe dataset derived from 61 ice cores collected during 10 field expeditions carried out between 1997 and 2012 in the Southern Ocean. Our key findings are that 1 concentrations of all forms of Fe (PFe, DFe, TDFe are at least a magnitude larger in fast ice and pack ice than in typical Antarctic surface waters; 2 DFe, PFe and TDFe behave differently when plotted against sea-ice salinity, suggesting that their distributions in sea ice are driven by distinct, spatially and temporally decoupled processes; 3 DFe is actively extracted from seawater into growing sea ice; 4 fast ice generally has more Fe-bearing particles, a finding supported by the significant negative correlation observed between both PFe and TDFe concentrations in sea ice and water depth; 5 the Fe pool in sea ice is coupled to biota, as indicated by the positive correlations of PFe and TDFe with chlorophyll a and particulate organic carbon; and 6 the vast majority of DFe appears to be adsorbed onto something in sea ice. This review also addresses the role of sea ice as a reservoir of Fe and its role in seeding seasonally ice-covered waters. We discuss the pivotal role of organic ligands in controlling DFe concentrations in sea ice and highlight the uncertainties that remain regarding the mechanisms of Fe incorporation in sea ice.

  6. Different processes lead to similar patterns: a test of codivergence and the role of sea level and climate changes in shaping a southern temperate freshwater assemblage

    Directory of Open Access Journals (Sweden)

    Barber Brian R

    2011-11-01

    Full Text Available Abstract Background Understanding how freshwater assemblages have been formed and maintained is a fundamental goal in evolutionary and ecological disciplines. Here we use a historical approach to test the hypothesis of codivergence in three clades of the Chilean freshwater species assemblage. Molecular studies of freshwater crabs (Aegla: Aeglidae: Anomura and catfish (Trichomycterus arealatus: Trichomycteridae: Teleostei exhibited similar levels of genetic divergences of mitochondrial lineages between species of crabs and phylogroups of the catfish, suggesting a shared evolutionary history among the three clades in this species assemblage. Results A phylogeny was constructed for Trichomycterus areolatus under the following best-fit molecular models of evolution GTR + I + R, HKY + I, and HKY for cytochrome b, growth hormone, and rag 1 respectively. A GTR + I + R model provided the best fit for both 28S and mitochondrial loci and was used to construct both Aegla phylogenies. Three different diversification models were observed and the three groups arose during different time periods, from 2.25 to 5.05 million years ago (Ma. Cladogenesis within Trichomycterus areolatus was initiated roughly 2.25 Ma (Late Pliocene - Early Pleistocene some 1.7 - 2.8 million years after the basal divergences observed in both Aegla clades. These results reject the hypothesis of codivergence. Conclusions The similar genetic distances between terminal sister-lineages observed in these select taxa from the freshwater Chilean species assemblage were formed by different processes occurring over the last ~5.0 Ma. Dramatic changes in historic sea levels documented in the region appear to have independently shaped the evolutionary history of each group. Our study illustrates the important role that history plays in shaping a species assemblage and argues against assuming similar patterns equal a shared evolutionary history.

  7. Sea surface temperature and sea ice variability in the sub-polar North Atlantic from explosive volcanism of the late thirteenth century

    DEFF Research Database (Denmark)

    Sicre, M.-A.; Khodri, M.; Mignot, J.

    2013-01-01

    In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and lo...... and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades.......In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and long......-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling...

  8. AMSR-E/Aqua Daily L3 25 km Tb and Sea Ice Concentration Polar Grids V002

    Data.gov (United States)

    National Aeronautics and Space Administration — The AMSR-E/Aqua Level-3 25 km daily sea ice product includes 6.9 - 89.0 GHz TBs and sea ice concentration averages (daily, ascending, and descending) on a 25 km...

  9. AMSR-E/Aqua Daily L3 25 km Tb and Sea Ice Concentration Polar Grids V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The AMSR-E/Aqua Level-3 25 km daily sea ice product includes 6.9 - 89.0 GHz TBs and sea ice concentration averages (daily, ascending, and descending) on a 25 km...

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

    Science.gov (United States)

    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.

  11. Simulated Solute Tempering.

    Science.gov (United States)

    Denschlag, Robert; Lingenheil, Martin; Tavan, Paul; Mathias, Gerald

    2009-10-13

    For the enhanced conformational sampling in molecular dynamics (MD) simulations, we present "simulated solute tempering" (SST) which is an easy to implement variant of simulated tempering. SST extends conventional simulated tempering (CST) by key concepts of "replica exchange with solute tempering" (REST, Liu et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 13749). We have applied SST, CST, and REST to molecular dynamics (MD) simulations of an alanine octapeptide in explicit water. The weight parameters required for CST and SST are determined by two different formulas whose performance is compared. For SST only one of them yields a uniform sampling of the temperature space. Compared to CST and REST, SST provides the highest exchange probabilities between neighboring rungs in the temperature ladder. Concomitantly, SST leads to the fastest diffusion of the simulation system through the temperature space, in particular, if the "even-odd" exchange scheme is employed in SST. As a result, SST exhibits the highest sampling speed of the investigated tempering methods.

  12. Thickness and surface-properties of different sea-ice regimes within the Arctic Trans Polar Drift: Data from summers 2001, 2004 and 2007

    Science.gov (United States)

    Rabenstein, L.; Hendricks, S.; Martin, T.; Pfaffhuber, A.; Haas, C.

    2010-12-01

    Large-scale sea-ice thickness and surface property data were obtained in three summers and in three different sea-ice regimes in the Arctic Trans-Polar Drift (TPD) by means of helicopter electromagnetic sounding. Distribution functions P of sea-ice thickness and of the height, spacing, and density of sails were analyzed to characterize ice regimes of different ages and deformations. Results suggest that modal ice thickness is affected by the age of a sea-ice regime and that the degree of deformation is represented by the shape of P. Mean thickness changes with both age and deformation. Standard error calculations showed that representative mean and modal thickness could be obtained with transect lengths of 15 km and 50 km, respectively, in less deformed ice regimes such as those around the North Pole. In heavier deformed ice regimes closer to Greenland, 100 km transects were necessary for mean thickness determination and a representative modal thickness could not be obtained at all. Mean sail height did not differ between ice regimes, whereas sail density increased with the degree of deformation. Furthermore, the fraction of level ice, open melt ponds, and open water along the transects were determined. Although overall ice thickness in the central TPD was 50% thinner in 2007 than in 2001, first-year ice (FYI) was not significantly thinner in 2007 than FYI in 2001, with a decrease of only 0.3 m. Thinner FYI in 2007 only occurred close to the sea-ice edge, where open water covered more than 10% of the surface. Melt pond coverage retrieved from laser measurements was 15% in both the 2004 MYI regime and the 2007 FYI regime.

  13. SBI AWS02-I CTD Data collected from the Polar Star in the Beaufort and Chukchi Seas (NODC Accession 0001290)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The field phase of the Shelf-Basin Interactions Experiment (SBI) began in 2002 with a series of three cruises to the Chukchi and Beaufort Seas. SBI is a...

  14. Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea.

    Science.gov (United States)

    Bourgeon, Sophie; Riemer, Astrid Kolind; Tartu, Sabrina; Aars, Jon; Polder, Anuschka; Jenssen, Bjørn Munro; Routti, Heli

    2017-10-01

    As apex predators, polar bears (Ursus maritimus) are among the most heavily polluted organisms in the Arctic. In addition to this anthropogenic stressor, climate warming has been shown to negatively affect their body condition, reproductive output and survival. Among potential underlying physiological mechanisms, thyroid hormones (THs), which control thermoregulation, metabolism and reproduction, can be affected by a variety of both natural and anthropogenic factors. While THs have been extensively used as proxies for pollution exposure in mammals, including polar bears, there is a lack of knowledge of their natural variations. In this context, we examined seasonal variations in body condition and circulating TH concentrations in free-ranging female polar bears. Females with variable reproductive status (i.e., solitary, with cubs of the year or with yearlings) were sampled from locations with contrasted sea ice conditions. Furthermore, we studied THs in relation to levels of organo-halogenated contaminants. As predicted, solitary females were in better condition than females caring for offspring, especially in spring. In addition, TH levels were lower in autumn compared to spring, although this seasonal effect was mainly observed in solitary females. Finally, the negative relationships between organochlorine and perfluoroalkyl substances and some THs suggest a possible alteration of homeostasis of THs. Since the latter relationships were only observed during spring, we emphasize the importance of considering the ecological factors when using THs as proxies for pollution exposure. Yet, the combined effects of natural and anthropogenic stressors on THs might impair the ability of polar bears to adapt to ongoing climate changes. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Jurassic–Cretaceous low paleolatitudes from the circum-Black Sea region Crimea and Pontides) due to True Polar Wander

    NARCIS (Netherlands)

    Meijers, M.J.M.; Langereis, C.G.; van Hinsbergen, D.J.J.; Kaymakcl, N.; Stephenson, R.A.

    2010-01-01

    In a recent study, paleomagnetic and paleoenvironmental data from Adria (as part of the African plate) suggest a trend toward much lower (~15°) latitudes from Early Jurassic to Earliest Cretaceous at the position of Adria than suggested by the apparent polar wander (APW) paths. The smoothing of

  16. Sailing the Open Polar Sea...Again: What Are You Teaching Your Children about the Arctic Ocean?

    Science.gov (United States)

    Stockard, James W. Jr.

    1989-01-01

    Relates how a blunder about the Arctic Ocean and the polar ice cap made by the author in his first year of teaching led to a successful learning experience. Lists five important discussion topics that social studies teachers should use to teach about this remote, but strategic, part of the world. (LS)

  17. Variability of particulate organic carbon concentration in the north polar Atlantic based on ocean color observations with Sea-viewing Wide Field-of-view Sensor (SeaWiFS)

    Science.gov (United States)

    Stramska, Malgorzata; Stramski, Dariusz

    2005-01-01

    We use satellite data from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to investigate distributions of particulate organic carbon (POC) concentration in surface waters of the north polar Atlantic Ocean during the spring summer season (April through August) over a 6-year period from 1998 through 2003. By use of field data collected at sea, we developed regional relationships for the purpose of estimating POC from remote-sensing observations of ocean color. Analysis of several approaches used in the POC algorithm development and match-up analysis of coincident in situ derived and satellite-derived estimates of POC resulted in selection of an algorithm that is based on the blue-to-green ratio of remote-sensing reflectance R(sub rs) (or normalized water-leaving radiance L(sub wn)). The application of the selected algorithm to a 6-year record of SeaWiFS monthly composite data of L(sub wn) revealed patterns of seasonal and interannual variability of POC in the study region. For example, the results show a clear increase of POC throughout the season. The lowest values, generally less than 200 mg per cubic meters, and at some locations often less than 50 mg per cubic meters, were observed in April. In May and June, POC can exceed 300 or even 400 mg per cubic meters in some parts of the study region. Patterns of interannual variability are intricate, as they depend on the geographic location within the study region and particular time of year (month) considered. By comparing the results averaged over the entire study region and the entire season (April through August) for each year separately, we found that the lowest POC occurred in 2001 and the highest POC occurred in 2002 and 1999.

  18. Measurements of the summer surface heat budget of the Northeast Water Polynya. USCGC Polar Sea cruise, July 15--August 15, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Minnett, P.J.

    1994-03-01

    A research cruise of the USCGC Polar Sea to the Northeast Water Polynya, off the eastern coast of Greenland (77--81{degree}N, 6--17{degree}W), was made from mid-July to mid-August of 1992 (NEWP `92) as the first field component of the multi-disciplinary study of a high-Arctic polynya funded by the NSF as part of the Arctic Systems Science program. Instruments to measure the components of the surface heat budget of the polynya were installed on a foremast at the bow of the ship. This report presents the measured variables and derived surface fluxes in graphical and tabulated form. Profiles of atmospheric temperature and humidity were taken using radiosondes, and these are also presented.

  19. Collaborative research on the Northeast Water Polynya: NEWP92 hydrographic data report. USCGC Polar Sea cruise, July 15--August 15, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, D.W.R.; Behrens, W.J. [Brookhaven National Lab., Upton, NY (United States); Hopkins, T.S.; Kinder, C. [North Carolina State Univ., Raleigh NC (United States). Dept. of Marine, Earth and Atmospheric Science; Deming, J. [Univ. of Washington, Seattle, WA (United States). School of Oceanography; Smith, W.O. [Univ. of Tennessee, Knoxville, TN (United States); Top, Z. [Univ. of Miami, Miami, FL (United States). Rosenstiel School of Marine and Atmospheric Sciences; Walsh, I.D. [Texas A& M Univ., College Station, TX (United States). Dept. of Oceanography

    1995-06-01

    The Northeast Water Polynya (NEW) off the northeast coast of Greenland was the focus of two cruises aboard the USCGC Polar Sea during the summers of 1992 and 1993. The cruises were supported by the National Science Foundation Arctic Systems Science (ARCSS) program and were part of the Arctic Ocean Science Board`s International Arctic Polynya Program. The Polar Sea cruises were designed as multidisciplinary studies to test hypotheses about the mechanisms of heat, water and carbon flow within and beyond the boundaries of the polynya. Preliminary results of the 1992 study have been described elsewhere. A collection of papers arising from the 1992 cruise have been published in a Special Section of the Journal of Geophysical Research. This data report presents the hydrographic and basic chemical observations made from CTD/Rosette casts during the 1992 cruise. The station positions cruise are plotted in Figure 1. Also included in the report are selected section plots and vertical profiles. A total of 130 CTD casts were made during the cruise, measuring pressure, temperature, conductivity, dissolved oxygen, fluorescence and light transmission. Discrete samples were collected in 10-liter, rosette-mounted, Niskin bottles and analyzed, from most casts, for: salinity, dissolved nutrients, dissolved oxygen, anthropogenic halocarbons (e.g., Freon gases), pigments, particulate organic carbon and nitrogen. Suspended particulate matter was analyzed at selected stations and these data were used to calibrate the CTD-transmissometer. Samples were collected from selected stations and depths for tritium and helium analyses, carbonate chemistry, as well as for measurements of bacterial abundance.

  20. Trichinella in arctic, subarctic and temperate regions

    DEFF Research Database (Denmark)

    Kapel, C. M O

    1997-01-01

    and the human activity are all very important interacting factors affecting epidemiology. In Greenland, where only sylvatic trichinellosis is present, the high prevalence in wildlife appears closely connected with polar bear hunting. In the Scandinavian countries, the prevalence of both sylvatic and domestic......The transmission and occurrence of Trichinella spp according to the zoogeography of different climatic conditions, socioeconomy and human activity are discussed. Comparing arctic, subarctic and temperate regions, it appears that the species of Trichinella present, the composition of the fauna...... populations may have epidemiological importance in relation to the recent changes in production and infrastructure in these former Soviet states....

  1. Aquarius Radiometer and Scatterometer Weekly-Polar-Gridded Products to Monitor Ice Sheets, Sea Ice, and Frozen Soil

    Science.gov (United States)

    Brucker, Ludovic; Dinnat, Emmanuel; Koenig, Lora

    2014-01-01

    Space-based microwave sensors have been available for several decades, and with time more frequencies have been offered. Observations made at frequencies between 7 and 183 GHz were often used for monitoring cryospheric properties (e.g. sea ice concentration, snow accumulation, snow melt extent and duration). Since 2009, satellite observations are available at the low frequency of 1.4 GHz. Such observations are collected by the Soil Moisture and Ocean Salinity (SMOS) mission, and the AquariusSAC-D mission. Even though these missions have been designed for the monitoring of soil moisture and sea surface salinity, new applications are being developed to study the cryosphere. For instance, L-band observations can be used to monitor soil freezethaw (e.g. Rautiainen et al., 2012), and thin sea ice thickness (e.g. Kaleschke et al., 2010, Huntemann et al., 2013). Moreover, with the development of satellite missions comes the need for calibration and validation sites. These sites must have stable characteristics, such as the Antarctic Plateau (Drinkwater et al., 2004, Macelloni et al., 2013). Therefore, studying the cryosphere with 1.4 GHz observations is relevant for both science applications, and remote sensing applications.

  2. Aquarius Radiometer and Scatterometer Weekly Polar-Gridded Products to Monitor Ice Sheets, Sea Ice, and Frozen Soil

    Science.gov (United States)

    Brucker, Ludovic; Dinnat, Emmanuel; Koenig, Lora

    2014-01-01

    Space-based microwave sensors have been available for several decades, and with time more frequencies have been offered. Observations made at frequencies between 7 and 183 GHz were often used for monitoring cryospheric properties (e.g. sea ice concentration, snow accumulation, snow melt extent and duration). Since 2009, satellite observations are available at the low frequency of 1.4 GHz. Such observations are collected by the Soil Moisture and Ocean Salinity (SMOS) mission, and the Aquarius/SAC-D mission. Even though these missions have been designed for the monitoring of soil moisture and sea surface salinity, new applications are being developed to study the cryosphere. For instance, L-band observations can be used to monitor soil freeze/thaw (e.g. Rautiainen et al., 2012), and thin sea ice thickness (e.g. Kaleschke et al., 2010, Huntemann et al., 2013). Moreover, with the development of satellite missions comes the need for calibration and validation sites. These sites must have stable characteristics, such as the Antarctic Plateau (Drinkwater et al., 2004, Macelloni et al., 2013). Therefore, studying the cryosphere with 1.4 GHz observations is relevant for both science applications, and remote sensing applications.

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

    Directory of Open Access Journals (Sweden)

    PL Yager

    2016-12-01

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

  4. Kajian Pembuatan Cokelat Batang dengan Metode Tempering dan Tanpa Tempering

    OpenAIRE

    Eti Indarti; Normalina Arpi; Slamet Budijanto*

    2013-01-01

    This research is aimed to improve stability of milk chocolate bars by tempering process. The making of chocolate bars consisted of two formulations, namely a higher fat bar (40%) and low fat bar (21.5%).The study includes the chocolate bar preparation with and without tempering results. The melting point of milk chocolate bars that use cocoa butter tempering (L1) is higher than the milk chocolate bars that use fat without tempering (L2) for all treatments. Solid fat content (SFC) of F1 has hi...

  5. Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

    Directory of Open Access Journals (Sweden)

    Schneider Andreas S

    2012-09-01

    Full Text Available Abstract Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM [Gilbert et al., Journal of the

  6. The polarization of light in coastal and open oceans: Reflection and transmission by the air-sea interface and application for the retrieval of water optical properties

    Science.gov (United States)

    Foster, Robert

    For decades, traditional remote sensing retrieval methods that rely solely on the spectral intensity of the water-leaving light have provided indicators of aquatic ecosystem health. With the increasing demand for new water quality indicators and improved accuracy of existing ones, the limits of traditional remote sensing approaches are becoming apparent. Use of the additional information intrinsic to the polarization state of light is therefore receiving more attention. One of the major challenges inherent in any above-surface determination of the water-leaving radiance, scalar or vector, is the removal of extraneous light which has not interacted with the water body and is therefore not useful for remote sensing of the water itself. Due in-part to the lack of a proven alternative, existing polarimeter installations have thus far assumed that such light was reflected by a flat sea surface, which can lead to large inaccuracies in the water-leaving polarization signal. This dissertation rigorously determines the full Mueller matrices for both surface-reflected skylight and upwardly transmitted light by a wind-driven ocean surface. A Monte Carlo code models the surface in 3D and performs polarized ray-tracing, while a vector radiative transfer (VRT) simulation generates polarized light distributions from which the initial Stokes vector for each ray is inferred. Matrices are computed for the observable range of surface wind speeds, viewing and solar geometries, and atmospheric aerosol loads. Radiometer field-of-view effects are also assessed. Validation of the results is achieved using comprehensive VRT simulations of the atmosphere-ocean system based on several oceanographic research cruises and specially designed polarimeters developed by the City College of New York: one submerged beneath the surface and one mounted on a research vessel. When available, additional comparisons are made at 9 km altitude with the NASA Research Scanning Polarimeter (RSP). Excellent

  7. Preliminary Polar Sea Trials of Nereid-UI: A Remotely Operated Underwater Vehicle for Oceanographic Access Under Ice

    Science.gov (United States)

    Whitcomb, L. L.; Jakuba, M.; German, C. R.; Bowen, A.; Yoerger, D.; Kinsey, J. C.; Mayer, L.; McFarland, C.; Suman, S.; Bailey, J.; Judge, C.; Elliott, S.; Gomez-Ibanez, D.; Taylor, C. L.; Machado, C.; Howland, J. C.; Kaiser, C.; Heintz, M.; Pontbriand, C.; O'Hara, L.; McDonald, G.; Boetius, A.

    2014-12-01

    We report the development and deployment of a remotely-controlled underwater robotic vehicle capable of being teleoperated under ice under real-time human supervision. The Nereid Under-Ice (Nereid-UI or NUI) vehicle enables exploration and detailed examination of biological and physical environments including the ice-ocean interface in marginal ice zones, in the water column of ice-covered seas, at glacial ice-tongues, and ice-shelf margins, delivering realtime high definition video in addition to survey data from on board acoustic, optical, chemical, and biological sensors. The vehicle employs a novel lightweight fiber-optic tether that will enable it to be deployed from a ship to attain standoff distances of up to 20 km from an ice-edge boundary. We conducted NUI's first under-ice deployments during the July 2014 F/V Polarstern PS86 expedition at 86° N 6 W° in the Arctic Ocean - near the Aurora hydrothermal vent site on the Gakkel Ridge approximately 200 km NE of Greenland. We conducted 4 dives to evaluate and develop NUI's overall functioning and its individual engineered subsystems. On each dive, dead-reckoning (Ice-locked Doppler sonar and north-seeking gyrocompass) complemented by acoustic ranging provided navigation, supporting closed-loop control of heading, depth, and XY position relative to the ice. Science operations included multibeam transects of under-ice topography, precision vertical profiles for the bio-sensor suite and IR/radiance sensor suite, IR/radiance/multibeam transects at constant depth interlaced with vertical profiles and upward-looking digital still-camera surveys of the ice, including areas rich with algal material. The fiber-optic tether remained intact throughout most of all 4 dives. Consistent with the NUI concept of operations, in 3 of 4 dives the fiber-optic tether eventually failed, and the vehicle was then commanded acoustically in a series of short-duration maneuvers to return to Polarstern for recovery. These preliminary

  8. Polar zoobenthos blue carbon storage increases with sea ice losses, because across-shelf growth gains from longer algal blooms outweigh ice scour mortality in the shallows.

    Science.gov (United States)

    Barnes, David K A

    2017-06-23

    One of the major climate-forced global changes has been white to blue to green; losses of sea ice extent in time and space around Arctic and West Antarctic seas has increased open water and the duration (though not magnitude) of phytoplankton blooms. Blueing of the poles has increases potential for heat absorption for positive feedback but conversely the longer phytoplankton blooms have increased carbon export to storage and sequestration by shelf benthos. However, ice shelf collapses and glacier retreat can calve more icebergs, and the increased open water allows icebergs more opportunities to scour the seabed, reducing zoobenthic blue carbon capture and storage. Here the size and variability in benthic blue carbon in mega and macrobenthos was assessed in time and space at Ryder and Marguerite bays of the West Antarctic Peninsula (WAP). In particular the influence of the duration of primary productivity and ice scour are investigated from the shallows to typical shelf depths of 500 m. Ice scour frequency dominated influence on benthic blue carbon at 5 m, to comparable with phytoplankton duration by 25 m depth. At 500 m only phytoplankton duration was significant and influential. WAP zoobenthos was calculated to generate ~10(7) , 4.5 × 10(6) and 1.6 × 10(6) tonnes per year (between 2002 and 2015) in terms of production, immobilization and sequestration of carbon respectively. Thus about 1% of annual primary productivity has sequestration potential at the end of the trophic cascade. Polar zoobenthic blue carbon capture and storage responses to sea ice losses, the largest negative feedback on climate change, has been underestimated despite some offsetting of gain by increased ice scouring with more open water. Equivalent survey of Arctic and sub-Antarctic shelves, for which new projects have started, should reveal the true extent of this feedback and how much its variability contributes to uncertainty in climate models. © 2017 John Wiley & Sons Ltd.

  9. "Complexity" in Polarity Transitions at the Matuyama-Brunhes Boundary and top Jaramillo in North Atlantic Deep-sea Sediments

    Science.gov (United States)

    Channell, J. E. T.

    2016-12-01

    Integrated Ocean Drilling Program (IODP) Expedition 303 to the North Atlantic provided 16 records of the Matuyama-Brunhes polarity transition (MBT) and the top Jaramillo transition, based on u-channel and discrete samples, from holes drilled at three sites (Sites U1304, U1305 and U1306) that have mean Brunhes sedimentation rates of 16-18 cm/kyr. The MBT occurs during the transition from marine isotope stage (MIS) 19.3 to MIS 18.4, with mid-point at 773 ka, and a transition duration of 5-8 kyr. The top Jaramillo occurs during MIS 28 at 992 ka with a similar 5 kyr transition duration. Combining the new records with previously published North Atlantic records (ODP Sites 983, 984 and 1063) yields a total of 24 high sedimentation rate records. The MBT yields a repetitive pattern of transitional field states as virtual geomagnetic poles (VGPs) move from high southern latitudes to loop over the Pacific, cluster in NE Asia, and transit into the mid-latitude South Atlantic before reaching high latitudes in the Northern Hemisphere. The VGPs for the top Jaramillo transition feature a loop over the Pacific, then occupation of the NE Asia cluster before transit over the Indian Ocean to high southerly latitudes. The North Atlantic MBT records described here are very different to the longitudinally constrained North Atlantic VGP paths from MBT records that are the basis for a 2007 Bayesian inversion of the MBT field. We conclude that the relatively low sedimentation rate ( 4 cm/kyr) records utilized in the Bayesian inversion have been heavily smoothed by the remanence acquisition process, and do not adequately represent the MBT field. The VGPs at the MBT and top Jaramillo, as measured in the North Atlantic, have similarities with excursion (Iceland Basin) VGP paths, and are apparently guided by maxima in downward vertical flux in the modern non-dipole (ND) field, implying longevity in ND features through time.

  10. Comparative visual ecophysiology of mid-Atlantic temperate reef fishes

    Directory of Open Access Journals (Sweden)

    Andrij Z. Horodysky

    2013-11-01

    The absolute light sensitivities, temporal properties, and spectral sensitivities of the visual systems of three mid-Atlantic temperate reef fishes (Atlantic spadefish [Ephippidae: Chaetodipterus faber], tautog [Labridae: Tautoga onitis], and black sea bass [Serranidae: Centropristis striata] were studied via electroretinography (ERG. Pelagic Atlantic spadefish exhibited higher temporal resolution but a narrower dynamic range than the two more demersal foragers. The higher luminous sensitivities of tautog and black sea bass were similar to other benthic and demersal coastal mid-Atlantic fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of the three species spanned 400–610 nm, with high likelihood of cone dichromacy providing the basis for color and contrast discrimination. Significant day-night differences in spectral responses were evident in spadefish and black sea bass but not tautog, a labrid with characteristic structure-associated nocturnal torpor. Atlantic spadefish responded to a wider range of wavelengths than did deeper-dwelling tautog or black sea bass. Collectively, these results suggest that temperate reef-associated fishes are well-adapted to their gradient of brighter to dimmer photoclimates, representative of their unique ecologies and life histories. Continuing anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may however impede visual foraging and reproductive signaling in temperate reef fishes.

  11. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the USCGC POLAR STAR in the Arctic Ocean and Beaufort Sea from 2002-07-15 to 2002-08-13 (NODC Accession 0115609)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115609 includes chemical, discrete sample, physical and profile data collected from USCGC POLAR STAR in the Arctic Ocean and Beaufort Sea from...

  12. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from the USCGC POLAR STAR in the Coral Sea, North Pacific Ocean and others from 2001-11-02 to 2002-04-23 (NODC Accession 0108234)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0108234 includes chemical, meteorological, physical and underway - surface data collected from USCGC POLAR STAR in the Coral Sea, North Pacific Ocean,...

  13. High concentrations of exopolymeric substances in Arctic winter sea ice: implications for the polar ocean carbon cycle and cryoprotection of diatoms

    Science.gov (United States)

    Krembs, C.; Eicken, H.; Junge, K.; Deming, J. W.

    2002-12-01

    Exopolymeric substances (EPS) produced by microorganisms play important roles in various aquatic, porous, and extreme environments. Only recently has their occurrence in sea ice been considered. We used macroscopic and microscopic approaches to study the content and possible ecological role of EPS in wintertime fast ice near Barrow, Alaska (71°20' N, 156°40' W). Using Alcian blue staining of melted ice samples, we observed high concentrations of EPS in all samples examined, ranging from 0.79 to 7.71 mg xanthan gum equivalents (XGEQV) l -1. Areal conversions to carbon equivalents yielded 1.5-1.9 g C m -2 ice in March and 3.3-4.0 g C m -2 in May (when the ice was thicker). Although EPS did not correlate with macronutrient or pigment data, the latter analyses indicated ongoing or recent biological activity in the ice within temperature horizons of -11°C to -9°C and warmer. EPS correlated positively with bacterial abundance (although no functional relationship could be deduced) and with dissolved organic carbon (DOC) concentrations. Ratios of EPS/DOC decreased at colder temperatures within the core, arguing against physical conversion of DOC to EPS during freezing. When sea-ice segments were maintained at representative winter temperatures (-5°C,-15°C and -25°C) for 3-14 months, the total EPS content increased significantly at rates of 5-47 μg XGEQV l -1 d -1, similar to published rates of EPS production by diatoms. Microscopic images of ice-core sections at these very cold temperatures, using a recently developed non-invasive method, revealed diatoms sequestered in spacious brine pockets, intact autofluorescent chloroplasts in 47% of the (pennate) diatoms observed, and indications of mucus in diatom-containing pores. The high concentrations of EPS detected in these winter ice cores represent a previously unrecognized form of organic matter that may contribute significantly to polar ocean carbon cycles, not only within the ice but after springtime release into

  14. Bringing Experience from the Field into the Classroom with the NOAA Teacher at Sea and PolarTREC Teacher Research Experience Programs

    Science.gov (United States)

    Eubanks, E. D.; Kohin, S.; Oberbauer, S.

    2008-12-01

    As a participant of the National Oceanic and Atmospheric Administration (NOAA), Teacher at Sea (2007) and the Arctic Research Consortium of the U.S., PolarTREC (2008) programs, I have had the opportunity to participate in hands-on research with leading scientific researchers from the tropics to the Arctic. These Teacher Researcher Experiences (TRE's) and the resulting relationships that have developed with the scientific community have been an asset to my professional development and have greatly enhanced my students' learning. The opportunity to participate in data collection and hands-on research with a NOAA researcher, Dr. Kohin, helped me bring shark, ocean, and ship science from my expedition onboard the NOAA Ship David Starr Jordan in the Channel Island region into my classroom. The new knowledge, experiences, and resources that I brought back allowed me to create lesson plans and host Shark Month--an activity that involved all 300 students in my school. My students were able to link real data regarding the location of sharks to practical application and still meet state standards. Likewise, the scientist from my PolarTREC expedition, Dr. Oberbauer, is assisting me in a long-term plan to incorporate his data into my classroom curricula. Already, my experiences from Barrow, Alaska, have been shared through webinars with my community and as a keynote speaker to over 600 Palm Beach County science teachers. We are also working together to develop a yearlong curriculum, in which my entire school of 300 students will discover interdisciplinary polar science. Participation in TRE's has been beneficial for my students and my community, but what is the return on the investment for the scientists who invited me to participate in their research? Both scientists have transferred their knowledge out of the laboratory and made a link between their research and a different generation--our future scientists. They become instrumental science leaders in a community of young

  15. AMSR-E/Aqua Daily L3 12.5 km Tb, Sea Ice Conc., & Snow Depth Polar Grids V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The AMSR-E/Aqua Level 3 12.5 km daily sea ice product includes 18.7 - 89.0 GHz TBs, sea ice concentration averages (asc & desc), and 5-day snow depth over sea...

  16. Kajian Pembuatan Cokelat Batang dengan Metode Tempering dan Tanpa Tempering

    Directory of Open Access Journals (Sweden)

    Eti Indarti

    2013-02-01

    Full Text Available This research is aimed to improve stability of milk chocolate bars by tempering process. The making of chocolate bars consisted of two formulations, namely a higher fat bar (40% and low fat bar (21.5%.The study includes the chocolate bar preparation with and without tempering results. The melting point of milk chocolate bars that use cocoa butter tempering (L1 is higher than the milk chocolate bars that use fat without tempering (L2 for all treatments. Solid fat content (SFC of F1 has higher solid phase at room temperature (55-60% in all treatments compared with milk chocolate bar F2 (40-43% and chocolate produced by UKM (Malaysia 40-48 % and soccolatte 35-38% at the same temperature (350C. Blooming was not formed on the milk chocolate bars containing cocoa butter L1, while the milk chocolate bars showed blooming with L2 treatment. Keywords: chocolate bar, tempering, moulding, melting point, solid fat content, blooming

  17. Anti-Lambda Polarization in High Energy pp Collisions withPolarized Beams

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qing-hua; Liang, Zuo-tang; Sichtermann, Ernst

    2005-11-06

    We study the polarization of the anti-Lambda particle in polarized high energy pp collisions at large transverse momenta. The anti-Lambda polarization is found to be sensitive to the polarization of the anti-strange sea of the nucleon. We make predictions using different parameterizations of the polarized quark distribution functions. The results show that the measurement of longitudinal anti-Lambda polarization can distinguish different parameterizations, and that similar measurements in the transversely polarized case can give some insights into the transversity distribution of the anti-strange sea of nucleon.

  18. Polar lows in the Labrador Sea based on the Moravian historical collection of meteorological data in Labrador and Greenland since the mid-18th century

    Science.gov (United States)

    Matiu, Michael; Lüdecke, Cornelia; Newell, Dianne; Menzel, Annette

    2017-04-01

    Systematically recorded daily instrumental meteorological data from the Moravian Brethern mission stations located on the east coast of Labrador and southwest coast of Greenland during the 18th, 19th and 20th centuries provide a most valuable source of historical climatological data in the Subarctic region. Although the collections of original data themselves are both scattered in physical location and fragmented in their coverage of time and place, and large amounts still need to be digitized, this data provides large potential for studying climate extreme events in this remote region. In this paper, we study polar lows (PLs). They are high-latitude intense maritime cyclones with only 200 to 1000 km in diameter, a short life-time of only two days, mostly occurring in wintertime, e.g. in the Norwegian, Barents, but also Labrador and Greenland seas. Due to high wind speeds exceeding 30 m s-1, high ocean waves and heavy snow showers, they constitute a major hazard risk difficult to forecast. Published papers indicate that with future climate warming, the frequency of PLs is predicted to decrease; however, climatologies of PLs for the last 7 decades (1948-2009) based on reanalysis data and satellite remote sensing products did not indicate any change in their mean annual frequency. In our digitized long-term dataset (1846-2015) for one Moravian station at Nain, Labrador, we identified PLs as follows: If there was a drop in air pressure of at least 30hPa during 48 hours, we marked it as a preliminary event. Then, each preliminary event was checked manually to see whether additional changes in air pressure, air temperature, wind direction and wind speed matched the known textbook example. If more than two variables showed the required pattern, the preliminary event was identified as PL. Our analysis revealed an average frequency of 5.6 PLs yr-1 for 1846-1853, 5.2 PLs yr-1(1882-1913), and 4.4 PLs yr-1 (1926-1939), largely confirming long-term averages for the more recent

  19. The Roles of Sea-Ice, Light and Sedimentation in Structuring Shallow Antarctic Benthic Communities.

    Directory of Open Access Journals (Sweden)

    Graeme F Clark

    Full Text Available On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics.

  20. The Roles of Sea-Ice, Light and Sedimentation in Structuring Shallow Antarctic Benthic Communities.

    Science.gov (United States)

    Clark, Graeme F; Stark, Jonathan S; Palmer, Anne S; Riddle, Martin J; Johnston, Emma L

    2017-01-01

    On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics.

  1. The Roles of Sea-Ice, Light and Sedimentation in Structuring Shallow Antarctic Benthic Communities

    Science.gov (United States)

    Clark, Graeme F.; Stark, Jonathan S.; Palmer, Anne S.; Riddle, Martin J.; Johnston, Emma L.

    2017-01-01

    On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics. PMID:28076438

  2. Consequences of change and variability in sea ice on marine ecosystem and biogeochemical processes during the 2007-2008 Canadian International Polar Year program

    OpenAIRE

    Barber, D.G.; Asplin, M.G.; Papakyriakou, T.N.; Miller, L.; Else, B.G.T.; Iacozza, J.; Mundy, C.J.; Gosslin, M.; Asselin, N.C.; Ferguson, S.; Lukovich, J.V.; Stern, G.A.; Gaden, A.; Pucko, M.; Geilfus, N.-X.

    2012-01-01

    Change and variability in the timing and magnitude of sea ice geophysical and thermodynamic state have consequences on many aspects of the arctic marine system. The changes in both the geophysical and thermodynamic state, and in particular the timing of the development of these states, have consequences throughout the marine system. In this paper we review the 'consequences' of change in sea ice state on primary productivity, marine mammal habitats, and sea ice as a medium for storage and tra...

  3. Photosynthetic acclimation and the estimation of temperate ice algal primary production in Saroma-ko Lagoon, Japan

    Science.gov (United States)

    Kudoh, Sakae; Robineau, Brigitte; Suzuki, Yoshihiro; Fujiyoshi, Yoshihiro; Takahashi, Masayuki

    1997-02-01

    Temporal changes in the sea ice environment, ice algal biomass and photosynthetic characteristics were studied at Saroma-ko Lagoon in Japan, the area where the southernmost seasonal sea ice in the northern hemisphere occurs. In 1992, the sea ice started to develop in early January and covered the entire lagoon surface in late January, when water temperatures at the center of the lagoon decreased below -1.7°C. High concentrations of ice algae in the bottom layer of the sea ice, where light levels were 0.5-2.8% of the surface irradiance, were visually confirmed in mid-February. The biomass increased in late February to a maximum of 38.25 mg Chl am -2 then suddenly decreased during stormy weather in early March. Afterwards it remained rather constant, with high values of 20-30 mg Chl am -2 until mid-March. Photosynthesis vs. light analysis revealed that ice algae in this lagoon had a low dark respiration rate of 0.024 mg C mg Chl a-1h -1 on average while the increase of photosynthesis at light levels lower than 25 μmol m -2s -1 showed gentle linear increases with increments of light intensity. However, the maximum photosynthetic rate and the efficiency of the photosynthesis at low light levels were rather low compared with values from previous studies in the polar sea ice areas. Nevertheless, in situ estimates of net diel photosynthesis and production, which were calculated with a numerical model using the photosynthetic parameters and hourly averaged light at the ice algal habitat, suggested that large positive values were expected throughout this study. In temperate sea ice areas like Saroma-ko, where there are day/night light cycles, ice algae that have a small net loss of carbon at night due to dark respiration could achieve positive photosynthesis and growth even though they do not show the efficient photosynthesis under low light as shown by polar ice algae.

  4. U.S. Geological Survey Polar Bear Mark-Recapture Records, Alaska Portion of the Southern Beaufort Sea, 2001-2010

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected by the U.S. Geological Survey, Alaska Science Center, Polar Bear Research Program as part of long-term research on the southern Beaufort...

  5. Denning Behavior Classifications Using Temperature Sensor Data on Collars Deployed on Polar Bears in the Southern Beaufort Sea, 1986-2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data include two spreadsheets. The first is average daily temperatures received via satellite transmitting collars deployed on polar bears in the southern...

  6. Biological rhythms during residence in polar regions.

    Science.gov (United States)

    Arendt, Josephine

    2012-05-01

    , in contrast to temperate zones where complete adaptation rarely occurs. A similar situation occurs on high-latitude North Sea oil installations, especially when working 18:00-06:00 h. Lack of conflicting light exposure (and "social obligations") is the probable explanation. Many have problems returning to day work, showing circadian desynchrony. Timed light treatment again has helped to restore normal phase/sleep in a small number of people. Postprandial response to meals is compromised during periods of desynchrony with evidence of insulin resistance and elevated triglycerides, risk factors for heart disease. Only small numbers of subjects have been studied intensively in polar regions; however, these observations suggest that suboptimal light conditions are deleterious to health. They apply equally to people living in temperate zones with insufficient light exposure.

  7. SBI AWS02-I Bottle and Nutrient Data collected from the Polar Star in the Beaufort and Chukchi Seas (NODC Accession 0001288)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The field phase of the Shelf-Basin Interactions Experiment (SBI) began in 2002 with a series of three cruises to the Chukchi and Beaufort Seas. SBI is a...

  8. Geothermal structure of the eastern Black Sea basin and the eastern Pontides orogenic belt: Implications for subduction polarity of Tethys oceanic lithosphere

    Directory of Open Access Journals (Sweden)

    Nafiz Maden

    2013-07-01

    Full Text Available The numerical results of thermal modeling studies indicate that the lithosphere is cold and strong beneath the Black Sea basin. The thermal lithospheric thickness increases southward from the eastern Pontides orogenic belt (49.4 km to Black Sea basin (152.2 km. The Moho temperature increases from 367 °C in the trench to 978 °C in the arc region. The heat flow values for the Moho surface change between 16.4 mW m−2 in the Black Sea basin and 56.9 mW m−2 in the eastern Pontides orogenic belt. Along the southern Black Sea coast, the trench region has a relatively low geothermal potential with respect to the arc and back-arc region. The numerical studies support the existence of southward subduction beneath the Pontides during the late Mesozoic–Cenozoic.

  9. On autochtonous organic production and its implication for the consolidation of temperate salt marshes

    DEFF Research Database (Denmark)

    Bartholdy, Jesper; Bartholdy, Anders; Kim, Daehyun

    2014-01-01

    The organic production related to minerogene salt marsh deposits represents a challenge to all attempts to model the development of these areas, and evaluate their chances of survival under different sea level scenarios. Salt marsh deposits on a typical temperate backbarrier saltmarsh area at the...

  10. Seasonal and Interannual Variability of Calcite in the Sub-Polar North Atlantic

    Science.gov (United States)

    Signorini, S. R.; McClain, C. R.

    2008-12-01

    Coccolithophores, among which Emiliania huxleyi (E. huxleyi) is the most abundant and widespread species, are considered to be the most productive calcifying organisms on Earth. They inhabit the surface layer (MLD ~20m) in highly stratified waters where light intensity is high. E. huxleyi often forms massive blooms in temperate and sub-polar oceans. Coupling of the coccolithophore organic carbon and carbonate pumps interact to consume (photosynthesis) and produce (calcification) CO2. The so-called Rain Ratio, defined as the ratio of particulate inorganic carbon (PIC) to particulate organic carbon (POC) in exported biogenic matter, determines the relative strength of the two biological carbon pumps and influences the flux of CO2 across the surface ocean - atmosphere interface. Here we use a combination of satellite ocean color algorithms and numerical model products to describe the seasonal and interannual variability of PIC in the sub-polar North Atlantic. Phytoplankton and calcite production have strong spatial variability. Nutrient supply, biomass and calcite concentrations are modulated by light and MLD seasonal cycle. The size, intensity, and location of coccolithophore blooms vary from year to year, but the peak bloom is always in June in the Central Basin (45°W - 10°W, 50°N - 65°N) and August in the Barents Sea. Calcification rates range from 5% to 27% of net primary production. The Barents Sea PIC production is about twice that of the Central Basin. Predicted freshening and warming of polar seas may increase stratification, thus favoring an increase in coccolithophore bloom development. However, although significant interannual changes were identified, there were no obvious trends in the satellite-derived PIC concentrations over the past 10 years.

  11. A selective integrated tempering method.

    Science.gov (United States)

    Yang, Lijiang; Qin Gao, Yi

    2009-12-07

    In this paper, based on the integrated tempering sampling we introduce a selective integrated tempering sampling (SITS) method for the efficient conformation sampling and thermodynamics calculations for a subsystem in a large one, such as biomolecules solvated in aqueous solutions. By introducing a potential surface scaled with temperature, the sampling over the configuration space of interest (e.g., the solvated biomolecule) is selectively enhanced but the rest of the system (e.g., the solvent) stays largely unperturbed. The applications of this method to biomolecular systems allow highly efficient sampling over both energy and configuration spaces of interest. Comparing to the popular and powerful replica exchange molecular dynamics (REMD), the method presented in this paper is significantly more efficient in yielding relevant thermodynamics quantities (such as the potential of mean force for biomolecular conformational changes in aqueous solutions). It is more important that SITS but not REMD yielded results that are consistent with the traditional umbrella sampling free energy calculations when explicit solvent model is used since SITS avoids the sampling of the irrelevant phase space (such as the boiling water at high temperatures).

  12. Temper Fragileness Study for RUL 2 Steel

    Directory of Open Access Journals (Sweden)

    Rodica Rădulea

    2007-10-01

    Full Text Available This paper presents an experimental study about the tenacity variation depending on the tempering temperature of the steel RUL2 grade, within q wide range of temperatures. By this analysis it is possible to study the cooling of the above mentioned heat treatment on the temper fragileness.

  13. Parallel tempering for the traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Percus, Allon [Los Alamos National Laboratory; Wang, Richard [UCLA MATH DEPT; Hyman, Jeffrey [UCLA MATH DEPT; Caflisch, Russel [UCLA MATH DEPT

    2008-01-01

    We explore the potential of parallel tempering as a combinatorial optimization method, applying it to the traveling salesman problem. We compare simulation results of parallel tempering with a benchmark implementation of simulated annealing, and study how different choices of parameters affect the relative performance of the two methods. We find that a straightforward implementation of parallel tempering can outperform simulated annealing in several crucial respects. When parameters are chosen appropriately, both methods yield close approximation to the actual minimum distance for an instance with 200 nodes. However, parallel tempering yields more consistently accurate results when a series of independent simulations are performed. Our results suggest that parallel tempering might offer a simple but powerful alternative to simulated annealing for combinatorial optimization problems.

  14. Polar low monitoring

    Science.gov (United States)

    Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid

    2010-05-01

    Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite

  15. Polarization, political

    NARCIS (Netherlands)

    Wojcieszak, M.; Mazzoleni, G.; Barnhurst, K.G.; Ikeda, K.; Maia, R.C.M.; Wessler, H.

    2015-01-01

    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass

  16. Overview of the molecular defense systems used by sea urchin embryos to cope with UV radiation.

    Science.gov (United States)

    Bonaventura, Rosa; Matranga, Valeria

    2017-07-01

    The sea urchin embryo is a well-recognized developmental biology model and its use in toxicological studies has been widely appreciated. Many studies have focused on the evaluation of the effects of chemical stressors and their mixture in marine ecosystems using sea urchin embryos. These are well equipped with defense genes used to cope with chemical stressors. Recently, ultraviolet radiation (UVR), particularly UVB (280-315 nm), received more attention as a physical stressor. Mainly in the Polar Regions, but also at temperate latitudes, the penetration of UVB into the oceans increases as a consequence of the reduction of the Earth's ozone layer. In general, UVR induces oxidative stress in marine organisms affecting molecular targets such as DNA, proteins, and lipids. Depending on the UVR dose, developing sea urchin embryos show morphological perturbations affecting mainly the skeleton formation and patterning. Nevertheless, embryos are able to protect themselves against excessive UVR, using mechanisms acting at different levels: transcriptional, translational and post-translational. In this review, we recommend the sea urchin embryo as a suitable model for testing physical stressors such as UVR and summarize the mechanisms adopted to deal with UVR. Moreover, we review UV-induced apoptotic events and the combined effects of UVR and other stressors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. The Effect of Tempering on Strength Properties and Seed Coat ...

    African Journals Online (AJOL)

    ... tempering on seed coat adhesion strength and mechanical strength of sorghum and millet grain kernels was investigated at different tempering durations. Tempering reduced the kernel breaking strength and had significant effect on seed coat adhesion strength. Tempering the grain for 60 minutes at ambient temperature ...

  18. The toxic benthic dinoflagellates of the genus Ostreopsis in temperate areas: a review

    OpenAIRE

    Stefano Accoroni; Cecilia Totti

    2016-01-01

    The genus Ostreopsis includes species largely distributed from tropical to temperate marine areas worldwide. Among the nine species of the genus, O. siamensis, O. mascarenensis, O. lenticularis and O. cf. ovata can produce toxins of the palytoxin group. In the last decade Ostreopsis cf. ovata and O. cf. siamensis originated intense blooms in all the rocky Mediterranean Sea coastal areas, typically during summer-late summer. The correct identification of Ostreopsis species in field samples is ...

  19. Comparisons of invasive plants in southern Africa originating from southern temperate, northern temperate and tropical regions

    Directory of Open Access Journals (Sweden)

    L. Henderson

    2006-08-01

    Full Text Available A subset of invasive alien plant species in southern Africa was analysed in terms of their history of introduction, rate of spread, countries/region of origin, taxonomy, growth forms, cultivated uses, weed status and current distribution in southern Africa, and comparisons made of those originating from south of the tropic of Capricorn, north of the tropic of Cancer and from the tropics. The subset of 233 species, belonging to 58 families, includes all important declared species and some potentially important species. Almost as many species originate from temperate regions (112 as from the tropics (121. Most southern temperate species came from Australia (28/36, most tropical species from tropical America (92/121 and most northern temperate species from Europe (including the Mediterranean and Asia (58/76. Transformers account for 33% of  all species. More transformers are of tropical origin (36 than of northern temperate (24 and southern temperate origin (18. However. 50% of southern temperate species are transformers, compared to 32% of northern temperate and 29% of tropical species. Southern temperate transformer species are mainly woody trees and shrubs that were established on a grand scale as silvicultural crops, barriers (hedges, windbreaks and screens and cover/binders. Most aquatics, herbs, climbers and succulent shrubs an. trom the tropics. Ornamentals are the single largest category of plants from all three regions, the tropics having contributed twice as many species as temperate regions.

  20. Comparisons of invasive plants in southern Africa originating from southern temperate, northern temperate and tropical regions

    Directory of Open Access Journals (Sweden)

    L. Henderson

    2006-12-01

    Full Text Available A subset of invasive alien plant species in southern Africa was analysed in terms of their history of introduction, rate of spread, countries/region of origin, taxonomy, growth forms, cultivated uses, weed status and current distribution in southern Africa, and comparisons made of those originating from south of the tropic of Capricorn, north of the tropic of Cancer and from the tropics. The subset of 233 species, belonging to 58 families, includes all important declared species and some potentially important species. Almost as many species originate from temperate regions (112 as from the tropics (121. Most southern temperate species came from Australia (28/36, most tropical species from tropical America (92/121 and most northern temperate species from Europe (including the Mediterranean and Asia (58/76. Transformers account for 33% of  all species. More transformers are of tropical origin (36 than of northern temperate (24 and southern temperate origin (18. However. 50% of southern temperate species are transformers, compared to 32% of northern temperate and 29% of tropical species. Southern temperate transformer species are mainly woody trees and shrubs that were established on a grand scale as silvicultural crops, barriers (hedges, windbreaks and screens and cover/binders. Most aquatics, herbs, climbers and succulent shrubs an. trom the tropics. Ornamentals are the single largest category of plants from all three regions, the tropics having contributed twice as many species as temperate regions.

  1. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  2. Comparison of sampling efficiency between simulated tempering and replica exchange

    OpenAIRE

    Zhang, Cheng; Ma, Jianpeng

    2008-01-01

    We compared the sampling efficiency of simulated tempering and replica exchange. Our results indicate that simulated tempering is superior to replica exchange if the parameters for temperature transition in simulated tempering are adjusted to be proportional to the partition function. It is shown that, in simulated tempering, the rate of traversing energy space of different temperatures is much higher than that in replica exchange, especially in the case of low tempering frequency and∕or larg...

  3. Comparison of sampling efficiency between simulated tempering and replica exchange.

    Science.gov (United States)

    Zhang, Cheng; Ma, Jianpeng

    2008-10-07

    We compared the sampling efficiency of simulated tempering and replica exchange. Our results indicate that simulated tempering is superior to replica exchange if the parameters for temperature transition in simulated tempering are adjusted to be proportional to the partition function. It is shown that, in simulated tempering, the rate of traversing energy space of different temperatures is much higher than that in replica exchange, especially in the case of low tempering frequency and/or larger temperature separations.

  4. Swimming of a Tiny Subtropical Sea Butterfly with Coiled Shell

    Science.gov (United States)

    Murphy, David; Karakas, Ferhat; Maas, Amy

    2017-11-01

    Sea butterflies, also known as pteropods, include a variety of small, zooplanktonic marine snails. Thecosomatous pteropods possess a shell and swim at low Reynolds numbers by beating their wing-like parapodia in a manner reminiscent of insect flight. In fact, previous studies of the pteropod Limacina helicina have shown that pteropod swimming hydrodynamics and tiny insect flight aerodynamics are dynamically similar. Studies of L. helicina swimming have been performed in polar (0 degrees C) and temperate conditions (12 degrees C). Here we present measurements of the swimming of Heliconoides inflatus, a smaller yet morphologically similar pteropod that lives in warm Bermuda seawater (21 degrees C) with a viscosity almost half that of the polar seawater. The collected H. inflatus have shell sizes less than 1.5 mm in diameter, beat their wings at frequencies up to 11 Hz, and swim upwards in sawtooth trajectories at speeds up to approximately 25 mm/s. Using three-dimensional wing and body kinematics collected with two orthogonal high speed cameras and time-resolved, 2D flow measurements collected with a micro-PIV system, we compare the effects of smaller body size and lower water viscosity on the flow physics underlying flapping-based swimming by pteropods and flight by tiny insects.

  5. Functional Reflective Polarizer for Augmented Reality and Color Vision Deficiency

    Science.gov (United States)

    2016-03-03

    435 (1992). 12. M. Neitz and J. Neitz, “Molecular genetics of color vision and color vision defects,” Arch. Ophthalmol. 118(5), 691–700 (2000). 13. T...reflective polarizer in the x direction should be as high as possible, thus it will not temper the output display spectra and cause color inaccuracy

  6. Polar predictions

    OpenAIRE

    Crame, Alistair; Francis, Jane; Robinson, Stuart; Bowman, Vanessa

    2014-01-01

    In an effort to improve understanding of faunal evolution and its relationship to climate change, the PALEOPOLAR project is challenging existing theories about the Early Cenozoic era using an integrated, multidisciplinary approach in the polar regions

  7. North Polar Erg

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form. This VIS image was taken at 81 degrees North latitude during Northern spring. This region of the north polar erg is dominated by a different form of dunes than yesterday's image. Image information: VIS instrument. Latitude 81.4, Longitude 121.9 East (238.1 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. On optical and physical properties of sea ice in the Baltic Sea

    OpenAIRE

    Uusikivi, Jari

    2013-01-01

    Sea ice has been recognized as one of the key elements of polar and sub-polar seas, including Baltic Sea. The existence of sea ice cover and its properties have influence to many aspects of marine biology, climate and seafaring. This thesis is concentrated on describing physical and optical properties of landfast ice, and also pack ice, in the Baltic Sea. The aim of the thesis is to use measurements to study the interactions between optical and physical properties of sea ice and how these can...

  9. Englacial Hydrology of Temperate Glaciers

    Science.gov (United States)

    Fountain, A. G.; Creyts, T. T.

    2015-12-01

    The englacial region of temperate glaciers is generally treated as a passive conveyor of water from the surface to the bed. Consequently, few studies have examined this region and relatively little is known. This is an important issue because englacial processes probably exert a first order control on the distribution of water to the subglacial hydraulic system. Controlling the water distribution probably controls the type of subglacial hydraulic features present and therefore sliding behavior. Certainly, englacial conduits play a major, if not primary, role in conveying water in the ablation zone. In regions of over-deepenings, areas highly crevassed, or in the accumulation zone, the importance of englacial conduits is less clear. Field studies have shown that intersecting englacial passageways in these regions are relatively common, implying that large water fluxes can drain efficiently through a network of fractures. Hypothetically, efficient drainage systems composed of englacial conduits develop in response to point input of large surface water fluxes. Where input is small and distributed, common to highly crevassed areas or the accumulation zone, water is probably routed through a network of englacial fractures. Glacier geometry may also play a role. Conduits may not develop in the over-deepened (closed basins) regions of a glacier requiring another flow pathway. That englacial fractures exist and can convey water presents a promising alternative. Measured rates of flow in fractures strongly suggest laminar conditions and a sufficient fracture density exists to accommodate the estimated water flux generated upstream by surface melt. The slow flow rates do not generate sufficient viscous heat to compensate expected rates of closure by freezing, however field observations and seismic evidence point to spontaneous fracture formation at depth that must regenerate the fracture network. It is unfortunate that englacial investigations are ignored in favor of

  10. Physical-Biogeochemical Interactions that Alter the Uptake of Atmospheric CO2 in the Barents Sea

    Science.gov (United States)

    Signorini, S. R.; Hakkinen, S. M.; McClain, C. R.

    2009-04-01

    The Barents Sea is characterized by significant calcification rates during summer promoted by intense coccolithophore blooms that peak during August. Coccolithophores, among which Emiliania huxleyi (E. huxleyi) is the most abundant and widespread species, are considered to be the most productive calcifying organisms on Earth. They inhabit the surface layer (MLD 20m) in highly stratified waters where light intensity is high. E. huxleyi often forms massive blooms in temperate and sub-polar oceans. Coupling of the coccolithophore organic carbon and carbonate pumps interact to consume (photosynthesis) and produce (calcification) CO2. The so-called Rain Ratio, defined as the ratio of particulate inorganic carbon (PIC) to particulate organic carbon (POC) in exported biogenic matter, determines the relative strength of the two biological carbon pumps and influences the flux of CO2 across the surface ocean - atmosphere interface. Here we use a combination of satellite ocean color algorithms, coupled ice-ocean model products, an SST-dependent pCO2 algorithm, and gas exchange parameterization to describe the seasonal and decadal variability of the air-sea CO2 flux in the Barents Sea. Model-derived SST and SSS (1955-2008) are used in conjunction with the pCO2 algorithm and carbonate chemistry to derive decadal trends of sea-air CO2 flux, pH and calcite saturation state. Phytoplankton and calcite production have strong spatial variability. Nutrient supply, biomass and calcite concentrations are modulated by light and MLD seasonal cycle. The size, intensity, and location of coccolithophore blooms vary from year to year, but the peak bloom is always in June in the Central Basin of the sub-polar North Atlantic (45oW - 10oW, 50oN - 65oN) and August in the Barents Sea. Calcification rates range from 5% to 27% of net primary production. The Barents Sea PIC production is about twice that of the Central Basin. Predicted freshening and warming of polar seas may increase stratification

  11. Biological Rhythms During Residence in Polar Regions

    Science.gov (United States)

    2012-01-01

    a week, in contrast to temperate zones where complete adaptation rarely occurs. A similar situation occurs on high-latitude North Sea oil installations, especially when working 18:00–06:00 h. Lack of conflicting light exposure (and “social obligations”) is the probable explanation. Many have problems returning to day work, showing circadian desynchrony. Timed light treatment again has helped to restore normal phase/sleep in a small number of people. Postprandial response to meals is compromised during periods of desynchrony with evidence of insulin resistance and elevated triglycerides, risk factors for heart disease. Only small numbers of subjects have been studied intensively in polar regions; however, these observations suggest that suboptimal light conditions are deleterious to health. They apply equally to people living in temperate zones with insufficient light exposure. PMID:22497433

  12. POLAR ICE: Integrating, Distributing and Visualising Ice Information Products for Operators in Polar Waters

    Science.gov (United States)

    Walker, Nick; Fleming, Andrew; Cziferszky, Andreas; Toudal Pedersen, Leif; Rasmussen, Till; Makynen, Marko; Berglund, Robin; Seitsonen, Lauri; Rudjord, Oystein; Solberg, Rune; Tangen, Helge; Axell, Lars; Saldo, Roberto; Melsheimer, Christian; Larsen, Hans Eilif; Puestow, Thomas; Arhturs, David; Flach, Dominie

    2016-08-01

    The POLAR ICE project has developed a system for integrating and delivering satellite derived ice information products to operators working in the economically and environmentally important Arctic and Antarctic regions. POLAR ICE has been supported by the European Commission's FP7 programme and undertaken by European and Canadian companies and institutes, who are all partners in the Polar View Earth Observation Limited (PVEO) company. It is the aim of PVEO to commercialise the service that has been developed and demonstrated as a part of POLAR ICE.Access to sea ice information derived from satellite earth observation data is critical to support the increasing numbers of Arctic and Antarctic shipping and off-shore operations and to protect the rapidly changing polar environment.To-date the development of sea ice information capabilities has addressed separate elements of complete service chains. In contrast POLAR ICE has linked these separate elements together, filled in known gaps and built a robust integrated service chain.

  13. Autodeformation of Carburized Steel during Tempering

    Directory of Open Access Journals (Sweden)

    Regita BENDIKIENĖ

    2013-03-01

    Full Text Available The article analyses the results of autodeformation registered during tempering of carburized steel. Test pieces for the tests were carburized till the different depth in order to examine influence of depth of carburization on the deformation of steel during heat treatment operation. Carburization was performed on the one surface of test pieces seeking to analyze extent of acted normal stresses to autodeformation of steel. Different bending loads were applied for analyzed steel from 5 MPa to 100 MPa. Deflection of test pieces was analyzed. The obtained results proved that size and direction of deflection were affected by depth of carburization. Particular results of stretched and compressed surface examination showed different behavior of test pieces during tempering process. Test pieces, which undergo deformation at the beginning of martensitic transformation, after unloading bend further. When tempered test pieces with assimetrically carburized layer bend during hardening, its direction and extent of autodeformation depend on depth of carburization and tempering temperature. Kinetics of autodeformation (during tempering is affected by difference of volume changes in the carburized part and in the unaffected low carbon part of specimen, and similarly by decomposition of retained austenite in the carburized part.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3820

  14. First Temperate Exoplanet Sized Up

    Science.gov (United States)

    2010-03-01

    Combining observations from the CoRoT satellite and the ESO HARPS instrument, astronomers have discovered the first "normal" exoplanet that can be studied in great detail. Designated Corot-9b, the planet regularly passes in front of a star similar to the Sun located 1500 light-years away from Earth towards the constellation of Serpens (the Snake). "This is a normal, temperate exoplanet just like dozens we already know, but this is the first whose properties we can study in depth," says Claire Moutou, who is part of the international team of 60 astronomers that made the discovery. "It is bound to become a Rosetta stone in exoplanet research." "Corot-9b is the first exoplanet that really does resemble planets in our solar system," adds lead author Hans Deeg. "It has the size of Jupiter and an orbit similar to that of Mercury." "Like our own giant planets, Jupiter and Saturn, the planet is mostly made of hydrogen and helium," says team member Tristan Guillot, "and it may contain up to 20 Earth masses of other elements, including water and rock at high temperatures and pressures." Corot-9b passes in front of its host star every 95 days, as seen from Earth [1]. This "transit" lasts for about 8 hours, and provides astronomers with much additional information on the planet. This is fortunate as the gas giant shares many features with the majority of exoplanets discovered so far [2]. "Our analysis has provided more information on Corot-9b than for other exoplanets of the same type," says co-author Didier Queloz. "It may open up a new field of research to understand the atmospheres of moderate- and low-temperature planets, and in particular a completely new window in our understanding of low-temperature chemistry." More than 400 exoplanets have been discovered so far, 70 of them through the transit method. Corot-9b is special in that its distance from its host star is about ten times larger than that of any planet previously discovered by this method. And unlike all such

  15. Thermal biology of the sub-polar–temperate estuarine crab Hemigrapsus crenulatus (Crustacea: Decapoda: Varunidae)

    Science.gov (United States)

    Cumillaf, Juan P.; Blanc, Johnny; Paschke, Kurt; Gebauer, Paulina; Díaz, Fernando; Re, Denisse; Chimal, María E.; Vásquez, Jorge; Rosas, Carlos

    2016-01-01

    ABSTRACT Optimum temperatures can be measured through aerobic scope, preferred temperatures or growth. A complete thermal window, including optimum, transition (Pejus) and critical temperatures (CT), can be described if preferred temperatures and CT are defined. The crustacean Hemigrapsus crenulatus was used as a model species to evaluate the effect of acclimation temperature on: (i) thermal preference and width of thermal window, (ii) respiratory metabolism, and (iii) haemolymph proteins. Dependant on acclimation temperature, preferred temperature was between 11.8°C and 25.2°C while CT was found between a minimum of 2.7°C (CTmin) and a maximum of 35.9°C (CTmax). These data and data from tropical and temperate crustaceans were compared to examine the association between environmental temperature and thermal tolerance. Temperate species have a CTmax limit around 35°C that corresponded with the low CTmax limit of tropical species (34–36°C). Tropical species showed a CTmin limit around 9°C similar to the maximum CTmin of temperate species (5–6°C). The maximum CTmin of deep sea species that occur in cold environments (2.5°C) matched the low CTmin values (3.2°C) of temperate species. Results also indicate that the energy required to activate the enzyme complex (Ei) involved in respiratory metabolism of ectotherms changes along the latitudinal gradient of temperature. PMID:26879464

  16. Thermal biology of the sub-polar–temperate estuarine crab Hemigrapsus crenulatus (Crustacea: Decapoda: Varunidae

    Directory of Open Access Journals (Sweden)

    Juan P. Cumillaf

    2016-03-01

    Full Text Available Optimum temperatures can be measured through aerobic scope, preferred temperatures or growth. A complete thermal window, including optimum, transition (Pejus and critical temperatures (CT, can be described if preferred temperatures and CT are defined. The crustacean Hemigrapsus crenulatus was used as a model species to evaluate the effect of acclimation temperature on: (i thermal preference and width of thermal window, (ii respiratory metabolism, and (iii haemolymph proteins. Dependant on acclimation temperature, preferred temperature was between 11.8°C and 25.2°C while CT was found between a minimum of 2.7°C (CTmin and a maximum of 35.9°C (CTmax. These data and data from tropical and temperate crustaceans were compared to examine the association between environmental temperature and thermal tolerance. Temperate species have a CTmax limit around 35°C that corresponded with the low CTmax limit of tropical species (34–36°C. Tropical species showed a CTmin limit around 9°C similar to the maximum CTmin of temperate species (5–6°C. The maximum CTmin of deep sea species that occur in cold environments (2.5°C matched the low CTmin values (3.2°C of temperate species. Results also indicate that the energy required to activate the enzyme complex (Ei involved in respiratory metabolism of ectotherms changes along the latitudinal gradient of temperature.

  17. Tempering of Low-Temperature Bainite

    Science.gov (United States)

    Peet, Mathew J.; Babu, Sudarsanam Suresh; Miller, Mike K.; Bhadeshia, H. K. D. H.

    2017-07-01

    Electron microscopy, X-ray diffraction, and atom probe tomography have been used to identify the changes which occur during the tempering of a carbide-free bainitic steel transformed at 473 K (200 °C). Partitioning of solute between ferrite and thin-films of retained austenite was observed on tempering at 673 K (400 °C) for 30 minutes. After tempering at 673 K (400 °C) and 773 K (500 °C) for 30 minutes, cementite was observed in the form of nanometre scale precipitates. Proximity histograms showed that the partitioning of solutes other than silicon from the cementite was slight at 673 K (400 °C) and more obvious at 773 K (500 °C). In both cases, the nanometre scale carbides are greatly depleted in silicon.

  18. NEW Fe-C-Mn-Si-Cr BEARING ALLOY: TEMPERING CURVES AND TEMPERED MARTENSITE EMBRITTLEMENT

    Directory of Open Access Journals (Sweden)

    José Benedito Marcomini

    2012-12-01

    Full Text Available SAE 52100 steel is not only used as a rolled raw material for bearing manufacturing but for building some rolling devices as well, such as guide rollers and straightener rollers. The purpose of this work is the characterization of a Fe-C-Mn-Si-Cr bearing alloy (SAE 52100 steel, modified with 1.74% Si by plotting the variation of quenched and tempered hardness curve (tempering curve and tempered martensite embrittlement susceptibility. The present application is based on the same idea as 300M steel regarding SAE 4340 steel. The effect of silicon on the kinetics of cementite precipitation leads to a rise in temperature of tempered martensite embrittlement. Quench and temper treatments were carried out and impact tests were performed with modified and commercial steels and the results were compared. Microstructure aspects are studied by scanning electron microscopy and x-ray diffraction analysis. The silicon alloyed steel presents great resistance to softening after tempering and no tempered martensite embrittlement.

  19. Polar Stratigraphy

    Science.gov (United States)

    1999-01-01

    These three images were taken on three different orbits over the north polar cap in April 1999. Each shows a different part of the same ice-free trough. The left and right images are separated by a distance of more than 100 kilometers (62 miles). Note the similar layers in each image.

  20. A Transnational Temperance Discourse? William Wells Brown, Creole Civilization, and Temperate Manners

    Directory of Open Access Journals (Sweden)

    Carole Lynn Stewart

    2011-03-01

    Full Text Available

    In the nineteenth century, temperance movements provided the occasion for a transnational discourse. These conversations possessed an intensity throughout Britain and the United States. In America temperance often became associated with strongly nationalistic Euro-American forms of identity and internal purity. Nonetheless, African American reformers and abolitionists bound themselves to temperance ideals in forming civil societies that would heal persons and provide communal modes of democratic freedom in the aftermath and recovery from chattel slavery. This paper explores the possibilities of temperance as a transnational discourse by considering its meaning in the life and work of the African American author and activist, William Wells Brown. Brown expressed a “creole civilization” that employed the stylistics of the trickster as a unique mode of restraint that revealed a peculiar power of passivity that was able to claim efficacy over one’s life and community. This meaning of temperance diverges from and dovetails with certain European meanings of civilization that were being forged in the nineteenth century. Brown was in conversation with temperance reformers in America, Britain, and Europe. He imagined the possible meaning of temperance in African, Egyptian, Christian, and Islamic civilizations. He speculated upon the possibility of temperance as a defining characteristic of a transnational civilization and culture that would provide spaces for the expression of democratic freedom. Brown reimagined temperance as a form of corporeal restraint that offered a direct and sacred relation to the land, space, people that appeared in between an ethnic nationalist ethos and the European imperialistic civilization.

  1. Response of a temperate demersal fish community to global warming

    Science.gov (United States)

    Punzón, A.; Serrano, A.; Sánchez, F.; Velasco, F.; Preciado, I.; González-Irusta, J. M.; López-López, L.

    2016-09-01

    Changes in the distribution of the demersal fish species have been identified in north-European Atlantic waters. The consequence of these changes has been a northward shift of the distribution limits and changes in richness. In this study a notable increase in demersal fish species richness per sampling station was detected in the southern Bay of Biscay. This rise was due to an increase in frequency of occurrence and abundance of the majority of fish species in the area (53% from the total species). A fisheries relate explanation was discarded because the mismatch between the changes in the fishing effort and the augment in frequency of occurrence and abundance. On the contrary, these changes are in agreement with expected response under the increasing temperature of the sea observed over the last three decades, associated to global warming. These changes were positively correlated with an increase in temperature of intermediate waters in the study area. In addition, some of these species showed a notable western displacements of the Centre of Gravity in the study area, which would be expected if temperate water species would be favoured by an increase in water temperature. Our results are consistent with studies in the North Sea, where many of these species showing widened distribution limits towards north. The analysis of the results shows that the studied ecosystem, the Bay of Biscay is under a meridionalization process. On the other hand, only one tropicalization event (Lepidotrigla dieuzeidei), was recorded, maybe due to the conservative restrictions applied in species selection.

  2. Multisystem altruistic metadynamics—Well-tempered variant

    Science.gov (United States)

    Hošek, Petr; Kříž, Pavel; Toulcová, Daniela; Spiwok, Vojtěch

    2017-03-01

    Metadynamics method has been widely used to enhance sampling in molecular simulations. Its original form suffers two major drawbacks, poor convergence in complex (especially biomolecular) systems and its serial nature. The first drawback has been addressed by introduction of a convergent variant known as well-tempered metadynamics. The second was addressed by introduction of a parallel multisystem metadynamics referred to as altruistic metadynamics. Here, we combine both approaches into well-tempered altruistic metadynamics. We provide mathematical arguments and trial simulations to show that it accurately predicts free energy surfaces.

  3. Multisystem altruistic metadynamics-Well-tempered variant.

    Science.gov (United States)

    Hošek, Petr; Kříž, Pavel; Toulcová, Daniela; Spiwok, Vojtěch

    2017-03-28

    Metadynamics method has been widely used to enhance sampling in molecular simulations. Its original form suffers two major drawbacks, poor convergence in complex (especially biomolecular) systems and its serial nature. The first drawback has been addressed by introduction of a convergent variant known as well-tempered metadynamics. The second was addressed by introduction of a parallel multisystem metadynamics referred to as altruistic metadynamics. Here, we combine both approaches into well-tempered altruistic metadynamics. We provide mathematical arguments and trial simulations to show that it accurately predicts free energy surfaces.

  4. Polar bear adipose tissue-derived stem cells as an in vitro model for effects of environmental contaminants on adipogenesis

    OpenAIRE

    Øygarden, Lene Eidsvik

    2015-01-01

    The polar bear (Ursus maritimus) is currently listed as a vulnerable species by the IUCN red list, mainly due to the predicted decline in sea ice caused by global warming. Polar bears are dependent on sea ice for hunting their main prey, the ringed seal (Phoca hispida). Shrinkage of sea ice can result in energetic challenges and increased mortality rates in polar bear populations, as their access to prey declines and the seasonal fasting period gets prolonged. Also affecting polar bears is th...

  5. Warm-temperate deciduous forests around the Northern Hemisphere

    National Research Council Canada - National Science Library

    Box E.O; Fujiwara K

    2015-01-01

    Warm-temperate deciduous forests are "southern", mainly oak-dominated deciduous forests, as found over the warmer southern parts of the temperate deciduous forest regions of East Asia, Europe and eastern North America...

  6. Effects of climate change on polar bears.

    Science.gov (United States)

    Wiig, Øystein; Aars, Jon; Born, Erik W

    2008-01-01

    In this article, we review the effects on polar bears of global warming that have already been observed, and try to evaluate what may happen to the polar bears in the future. Many researchers have predicted a wide range of impacts of climate change on polar bear demography and conditions. A predicted major reduction in sea ice habitat will reduce the availability of ice associated seals, the main prey of polar bears, and a loss and fragmentation of polar bear habitat will ultimately lead to large future reductions in most subpopulations. It is likely that polar bears will be lost from many areas where they are common today and also that the total population will change into a few more distinctly isolated populations.

  7. Seasonal change of steric sea level in the GIN seas

    Science.gov (United States)

    Li, Lei; Wang, Huijuan; Sun, Ruili

    2011-03-01

    The Greenland Sea, Iceland Sea, and Norwegian Sea (GIN seas) form the main channel connecting the Arctic Ocean with other Oceans, where significant water and energy exchange take place, and play an important role in global climate change. In this study steric sea level, associated with temperature and salinity, in the GIN seas is examined based on analysis of the monthly temperature and salinity fields from Polar science center Hydrographic Climatology (PHC3.0). A method proposed by Tabata et al. is used to calculate steric sea level, in which, steric sea level change due to thermal expansion and haline contraction is termed as the thermosteric component (TC) and the halosteric component (SC), recpectively. Total steric sea level (TSSL) change is the sum of TC and SC. The study shows that SC is making more contributions than TC to the seasonal change of TSSL in the Greenland Sea, whereas TC contributes more in the Norwegian and the Iceland Seas. Annual variation of TSSL is larger than 50 mm over most regions of the GIN Seas, and can be larger than 200 mm at some locations such as 308 mm at 76.5°N, 12.5°E and 246 mm at 77.5°N, 17.5°W.

  8. The Temperance Movement and Social Work

    Science.gov (United States)

    Murdach, Allison D.

    2009-01-01

    This article examines a forgotten episode in social work history: the involvement of the profession in the temperance movement in the late 19th and early 20th centuries. Though some notable social workers such as Jane Addams, Robert A. Woods, and Representative Jeannette Rankin (the first woman elected to the U.S. Congress), championed the…

  9. Simulation of quenching and tempering of steels

    Science.gov (United States)

    Jin, Long

    An efficient simulation method, which includes microstructure, temperature and stress analysis applicable to both quenching and tempering processes, is developed and implemented using the commercial FEM package ABAQUS. This simulation encompasses phase transformations and their effects on the temperature distribution and stress/strain evolution, including the dependency of material properties on temperature and microstructure, transformation strains, latent heats and transformation plasticity. Three different multi-phase constitutive models, namely the average property model, the Voigt model and the Reuss model, have been implemented. The average property model is based on the linear mixture of material properties of different phase, while the Voigt model assumes the same strain field in all phases and the Reuss model assumes the iso-stress field. The simulation model has been applied to quenching and tempering of modified 4320 steel. Experiments of tempering and quenching on carburized circular plates of the same steel have been performed. The calculated distortion and residual stress profiles are in good agreement with corresponding measurements made in experiments and thus verifies the correctness of the model. The simulation model developed in this study is a useful design tool for quenching and tempering as well as machining of steels.

  10. Polar Codes

    Science.gov (United States)

    2014-12-01

    added by the decoder is K/ρ+Td. By the last assumption, Td and Te are both ≤ K/ρ, so the total latency added is between 2K/ρ and 4K /ρ. For example...better resolution near the decision point. Reference [12] showed that in decoding a (1024, 512) polar code, using 6-bit LLRs resulted in per- formance

  11. Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments.

    Science.gov (United States)

    Nauendorf, Alice; Krause, Stefan; Bigalke, Nikolaus K; Gorb, Elena V; Gorb, Stanislav N; Haeckel, Matthias; Wahl, Martin; Treude, Tina

    2016-02-15

    To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Marine diatoms in polar and sub-polar environments and their application to Late Pleistocene paleoclimate reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Crosta, Xavier, E-mail: x.crosta@epoc.u-bordeaux1.fr [UMR-CNRS 5805 EPOC, Universite Bordeaux 1, Avenue des Facultes, 33405 Talence Cedex (France)

    2011-05-15

    Diatoms are one of the major phytoplankton groups in polar and sub-polar marine environments along with green algae and chrysophytes. Diatoms are composed of two components, a two-valve test made of amorphous silica and an organic cell encapsulated into the test. Mucilage covering the test and proteins embedded in the silica lattice of the test completes the organic pool of the diatoms. The preservation of these two components into deep-sea sediments allows for a large set of diatom-based proxies to infer past oceanographic and climatic changes in polar and sub-polar marine environments. Most diatom species in polar and sub-polar marine environments exhibit a narrow range of ecological preferences, especially in terms of sea-surface temperature and sea ice conditions. Preserved diatom assemblages in deep-sea sediments mirror the diatom assemblages in the phytoplankton. It is subsequently possible to extrapolate the relationships between diatom assemblages in surface sediments and modern parameters to down-core fossil assemblages to document past changes in sea-surface temperatures and sea ice conditions. Congruent analysis of biogenic silica and organic carbon and stable isotope ratios (O, Si in the silica matrix and C, N in the diatom-intrinsic organic matter) provides information on siliceous productivity, nutrient cycling and water mass circulation. Measurements of diatom biomarkers give complementary information on sea ice conditions and siliceous productivity.

  13. Antibacterial and anti-PAF activity of lipid extracts from sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata).

    Science.gov (United States)

    Nasopoulou, Constantina; Karantonis, Haralabos C; Andriotis, Michalis; Demopoulos, Constantinos A; Zabetakis, Ioannis

    2008-11-15

    The anti-PAF and the antibacterial activities of lipid extracts obtained from cultured sea bass (Dicentrarchus labrax) and cultured gilthead sea bream (Sparus aurata) were evaluated. Total lipids of sea bass and gilthead sea bream exerted PAF-like activity while, in higher amounts they inhibited this PAF activity. Neutral lipids of both sea bass and gilthead sea bream contained only PAF antagonists while the polar lipid fractions contained both PAF antagonists and agonists. Total lipids of sea bass exhibited stronger PAF-like activity than did those of gilthead sea bream; however, neutral lipids of sea bass contained stronger PAF antagonists than did gilthead sea bream. Total lipids of both sea bass and gilthead sea bream exhibited antibacterial activity only towards Staphylococcus aureus (S. aureus) with those of sea bass being more potent. Subsequently, neutral lipids of both sea bass and gilthead sea bream also showed antibacterial activity against S. aureus and less so towards Escherichia coli (E. coli), while only neutral lipids of sea bass showed antibacterial activity against Enterococcusfaecalis (E. faecalis). Sea bass neutral lipids were more active against S. aureus than were those of gilthead sea bream, while their activity towards E. coli was similar. Polar lipids of both sea bass and gilthead sea bream showed antibacterial activity against all bacteria strains. Sea bass polar lipids were more active towards S. aureus than were those of gilthead sea bream, while their activities against E. faecalis and E. coli were the same. The detected antibacterial activities of the lipid extracts isolated from sea bass and gilthead sea bream were observed in amounts equal to those that exerted either PAF inhibition or PAF-like activity, suggesting that PAF antagonists and agonists of fish lipids may be responsible for the antibacterial activity. Copyright © 2008 Elsevier Ltd. All rights reserved.

  14. Polar Unconformity

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1 19 August 2004 The arrows (see Figure 1) in this July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image indicate the location of an unconformity in the layered sequence of the martian north polar cap. An unconformity is a geologic term that indicates a break in the depositional record of a sedimentary deposit. In this case, the change is recorded by the presence of a series of polar layers that are truncated (cut off) along the line of arrows. The erosion that cut these layers along a gentle slope were later covered by a new set of layers that occur from the arrow tips upward to the top of the sequence shown here. The image is located near 85.2oN, 7.3oW. The bright features in the lower third of the image are frost-covered sand dunes. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the top/upper right.

  15. Norwegian North Polar Expedition 1893-1896: Oceanographic Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains water depth, temperature, specific gravity, salinity, and density measurements from the North Polar Basin and the Barents Sea, gathered by...

  16. World temperate fruit production: characteristics and challenges

    Directory of Open Access Journals (Sweden)

    Jorge B. Retamales

    2011-10-01

    Full Text Available In the last 30 years world population has increased 70% but per capita global fruit consumption is only 20% higher. Even though tropical and temperate fruit have similar contributions to the 50 kg/person/year of US consumption of fresh fruit, in the last 30 years this has been slightly greater for temperate fruit. Within fruit consumption, the largest expansion has been for organic fruit which increased more than 50% in the 2002-2006 period. The largest expansion of area planted in the 1996-2006 has been for kiwi (29% and blueberries (20%, while apples (-24% and sour cherries (-13% have had the largest reductions. Nearly 50% of the total global volume of fruit is produced by 5 countries: China, USA, Brazil, Italy and Spain. The main producer (China accounts for 23% of the total. While the main exporters are Spain, USA and Italy, the main importers are Germany, Russia and UK. Demands for the industry have evolved towards quality, food safety and traceability. The industry faces higher productions costs (labor, energy, agrichemicals. The retailers are moving towards consolidation while the customers are changing preferences (food for health. In this context there is greater pressure on growers, processors and retailers. Emerging issues are labor supply, climate change, water availability and sustainability. Recent developments in precision agriculture, molecular biology, phenomics, crop modelling and post harvest physiology should increase yields and quality, and reduce costs for temperate fruit production around the world.

  17. The effect of tempering temperature on pitting corrosion resistance of 420 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Anwar, Moch Syaiful, E-mail: moch026@lipi.go.id; Prifiharni, Siska, E-mail: sisk002@lipi.go.id; Mabruri, Efendi, E-mail: effe004@lipi.go.id [Research Center for Metallurgy and Materials – Indonesian Institute of Sciences (LIPI) Kawasan PUSPIPTEK Building 470 – South of Tangerang – Banten – 15314 (Indonesia)

    2016-04-19

    The AISI Type 420 stainless steels are commonly used to steam generators, mixer blades, etc. These stainless steels are most prone to pitting in dissolved Cl{sup −} containing environments. In this paper, the effect of tempering temperature on pitting corrosion resistance of AISI Type 420 stainless steels was studied. The AISI Type 420 stainless steels specimens were heat treated at the temperature of 1050°C for 1 hour to reach austenite stabilization and then quench in the oil. After that, the specimens were tempered at the temperature of 150, 250, 350 and 450°C for 30 minutes and then air cooled to the room temperature. The electrochemical potentiodynamic polarization test was conducted at 3.5% sodium chloride solution to evaluate corrosion rate and pitting corrosion behaviour. The Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) were used to evaluate the pitting corrosion product. The result have shown that highest pitting potential was found in the sample tempered at 250°C and corrosion pits were found to initiate preferentially around chromium carbides.

  18. The effect of tempering temperature on pitting corrosion resistance of 420 stainless steels

    Science.gov (United States)

    Anwar, Moch. Syaiful; Prifiharni, Siska; Mabruri, Efendi

    2016-04-01

    The AISI Type 420 stainless steels are commonly used to steam generators, mixer blades, etc. These stainless steels are most prone to pitting in dissolved Cl- containing environments. In this paper, the effect of tempering temperature on pitting corrosion resistance of AISI Type 420 stainless steels was studied. The AISI Type 420 stainless steels specimens were heat treated at the temperature of 1050°C for 1 hour to reach austenite stabilization and then quench in the oil. After that, the specimens were tempered at the temperature of 150, 250, 350 and 450°C for 30 minutes and then air cooled to the room temperature. The electrochemical potentiodynamic polarization test was conducted at 3.5% sodium chloride solution to evaluate corrosion rate and pitting corrosion behaviour. The Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) were used to evaluate the pitting corrosion product. The result have shown that highest pitting potential was found in the sample tempered at 250°C and corrosion pits were found to initiate preferentially around chromium carbides.

  19. Gene transcription in polar bears (Ursus maritimus) from disparate populations

    Science.gov (United States)

    Bowen, Lizabeth; Miles, A. Keith; Waters, Shannon C.; Meyerson, Randi; Rode, Karyn D.; Atwood, Todd C.

    2015-01-01

    Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

  20. A Molecular Survey of Ulva (Chlorophyta) in Temperate Australia Reveals Enhanced Levels of Cosmopolitanism.

    Science.gov (United States)

    Kirkendale, Lisa; Saunders, Gary W; Winberg, Pia

    2013-02-01

    The green algal genus Ulva includes a speciose group of marine macroalgae inhabiting shallow seas worldwide. Although algal blooms in Asia highlight the opportunistic nature of several "nuisance" species, recent research clearly reveals important positive benefits of Ulva. Applied research requires accurate, reliable, and rapid identification, however, identification of Ulva spp. has met with con-siderable difficulty. Consequently, many have turned to molecular markers to aid in taxonomy. Previous studies of plants and algae have relied heavily on ITS and rbcL. Recently, tufA has been presented as a suitable barcoding gene to facilitate species-level identification of green macroalgae and it is used here to explore the diversity of Ulva spp. in temperate Australia. Ninety Ulva specimens collected from 38 sites across five states were sequenced for this gene region with exemplars from each genetic group also sequenced for rbcL to test for congruence. Collections of Australian Ulva spp. were compared to samples from Asia and North America and exhibited trends consistent with recent studies in terms of species relationships. Results support an overwhelmingly cosmopolitan flora in temperate Australia that contrasts with other Australasian surveys of Ulva that report a greater number of endemics and new species. Four new records, as well as numerous range extensions for taxa already known from the country, are documented. Evidence for three nonindigenous Ulva species in temperate Australia is discussed. © 2012 Phycological Society of America.

  1. Oceanic temperate forest versus warm temperate rainforest: a reply to Grubb et al. (2017)

    DEFF Research Database (Denmark)

    McGlone, Matt S.; Buitenwerf, Robert; Richardson, Sarah J.

    2017-01-01

    that they ‘see no virtue in using climatic variables to define a [vegetation] formation type’, and then discuss problems with the climate- based global biome schemes of Holdridge (1947), Whittaker (1970), Box (1981) and Prentice et al. (1992). As our oceanic temperate forest (OTF) concept is underpinned......Grubb et al. (2017) point out that we (McGlone et al. 2016) erroneously stated that the definition of warm temperate rain forest (WTRF; Grubb et al. 2013) was based in part on climatic criteria. We apologise: their text made clear that this was not the case. However, they go on to say...... by climatic variables, and as they suggest that it largely falls within their WTRF and cool temperate rain forest (CTRF) concepts, we take this opportunity to further discuss the relative merits of these contrasting ways of classifying vegetation cover....

  2. PENGARUH VARIASI SUHU PADA PROSES SELF TEMPERING DAN VARIASI WAKTU TAHAN PADA PROSES TEMPERING TERHADAP SIFAT MEKANIS BAJA AISI 4140

    Directory of Open Access Journals (Sweden)

    Sunardi Sunardi

    2016-07-01

    Full Text Available Tujuan penelitian ini adalah untuk mengetahui sifat mekanis pada baja AISI 4140 dengan proses tempering dengan variasi waktu tahan dan variasi suhu pada proses self tempering. Material terlebih dahulu dipanaskan pada suhu 850°C, di tahan dengan waktu 14 dan 28 menit, media pendinginan adalah Oli SAE 20. Pada proses tempering baja dipanaskan kembali dengan suhu 200°C di tahan dengan waktu 30 dan 120 menit. Sedangkan untuk proses self tempering, baja di panaskan pada suhu 850°C di tahan dengan waktu 14 dan 28 menit kemudian didinginkan, suhu yang harus dicapai pada pendinginan adalah 200°C, 400°C dan 600°C. Proses tempering dengan variasi waktu tahan mempunyai nilai kekerasan terbesar 50,1 HRC dengan waktu tahan 120 menit, sedangkan nilai kekerasan terbesar pada proses self tempering dengan variasi suhu adalah 29,68 HRC pada suhu 200°C. Nilai ketangguhan terbesar pada saat proses tempering adalah 0,341 (J/mm2 dengan waktu tahan 120 menit, sedangkan pada saat proses self tempering ketangguhan terbesar pada suhu 600°C dengan nilai 0,375 (J/mm2. Laju korosi terbesar pada saat tempering adalah 0,055 (mpy dengan waktu tahan 30 menit, sedangkan pada saat proses self tempering laju korosi terbesar pada suhu 400°C dengan nilai 0,0388 (mpy. 

  3. Simulated Tempering and Swapping on Mean-Field Models

    OpenAIRE

    Bhatnagar, Nayantara; Randall, Dana

    2015-01-01

    Simulated and parallel tempering are families of Markov Chain Monte Carlo algorithms where a temperature parameter is varied during the simulation to overcome bottlenecks to convergence due to multimodality. In this work we introduce and analyze the convergence for a set of new tempering distributions which we call \\textit{entropy dampening}. For asymmetric exponential distributions and the mean field Ising model with and external field simulated tempering is known to converge slowly. We show...

  4. Population substructure and space use of Foxe Basin polar bears

    OpenAIRE

    Sahanatien, Vicki; Peacock, Elizabeth; Derocher, Andrew E

    2015-01-01

    Climate change has been identified as a major driver of habitat change, particularly for sea ice-dependent species such as the polar bear (Ursus maritimus). Population structure and space use of polar bears have been challenging to quantify because of their circumpolar distribution and tendency to range over large areas. Knowledge of movement patterns, home range, and habitat is needed for conservation and management. This is the first study to examine the spatial ecology of polar bears in th...

  5. Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

    Science.gov (United States)

    Steven C. Amstrup; Hal Caswell; Eric DeWeaver; Ian Stirling; David C. Douglas; Bruce G. Marcot; Christine M. Hunter

    2009-01-01

    Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears (Ursus maritimus). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior...

  6. Hydrology and morphology of two river mouth regions (temperate Vistula Delta and subtropical Red River Delta

    Directory of Open Access Journals (Sweden)

    Zbigniew Pruszak

    2005-09-01

    Full Text Available The paper presents a comparative analysis of two different river mouths from two different geographical zones (subtropical and temperate climatic regions. One is the multi-branch and multi-spit mouth of the Red River on the Gulf of Tonkin (Vietnam, the other is the smaller delta of the river Vistula on a bay of the Baltic Sea (Poland. The analysis focuses on the similarities and differences in the hydrodynamics between these estuaries and the adjacent coastal zones, the features of sediment transport, and the long-term morphodynamics of the river outlets. Salinity and water level are also discussed, the latter also in the context of the anticipated global effect of accelerated sea level rise. The analysis shows that the climatic and environmental conditions associated with geographical zones give rise to fundamental differences in the generation and dynamic evolution of the river mouths.

  7. Impacts of Polar Changes on the UV-induced Mineralization of Terrigenous Dissolved Organic Matter.

    Science.gov (United States)

    Sulzberger, Barbara; Arey, J Samuel

    2016-07-05

    Local climates in the Northern and Southern Hemisphere are influenced by Arctic Amplification and by interactions of the Antarctic ozone hole with climate change, respectively. Polar changes may affect hydroclimatic conditions in temperate regions, for example, by increasing the length and intensity of precipitation events at Northern Hemisphere midlatitudes. Additionally, global warming has led to the thawing of ancient permafrost soils, particularly in Arctic regions, due to Arctic Amplification. Both heavy precipitation events and thawing of permafrost are increasing the net transfer of terrestrially derived dissolved organic matter (DOM) from land to surface waters. In aquatic ecosystems, UV-induced oxidation of terrigenous DOM (tDOM) produces atmospheric CO2 and this process is one of several mechanisms by which natural organic matter in aquatic and soil environments may play an important role in climate feedbacks. The Arctic is particularly affected by these processes: for example, melting of Arctic sea ice allows solar UV radiation to penetrate into the ice-free Arctic Ocean and to cause photochemical reactions that result in bleaching and mineralization of tDOM. Open questions, in addition to those shown in the Graphical Abstract, remain regarding the resulting contributions of tDOM photomineralization to CO2 production and global warming.

  8. Polar bears in a warming climate.

    Science.gov (United States)

    Derocher, Andrew E; Lunn, Nicholas J; Stirling, Ian

    2004-04-01

    Polar bears (Ursus maritimus) live throughout the ice-covered waters of the circumpolar Arctic, particularly in near shore annual ice over the continental shelf where biological productivity is highest. However, to a large degree under scenarios predicted by climate change models, these preferred sea ice habitats will be substantially altered. Spatial and temporal sea ice changes will lead to shifts in trophic interactions involving polar bears through reduced availability and abundance of their main prey: seals. In the short term, climatic warming may improve bear and seal habitats in higher latitudes over continental shelves if currently thick multiyear ice is replaced by annual ice with more leads, making it more suitable for seals. A cascade of impacts beginning with reduced sea ice will be manifested in reduced adipose stores leading to lowered reproductive rates because females will have less fat to invest in cubs during the winter fast. Non-pregnant bears may have to fast on land or offshore on the remaining multiyear ice through progressively longer periods of open water while they await freeze-up and a return to hunting seals. As sea ice thins, and becomes more fractured and labile, it is likely to move more in response to winds and currents so that polar bears will need to walk or swim more and thus use greater amounts of energy to maintain contact with the remaining preferred habitats. The effects of climate change are likely to show large geographic, temporal and even individual differences and be highly variable, making it difficult to develop adequate monitoring and research programs. All ursids show behavioural plasticity but given the rapid pace of ecological change in the Arctic, the long generation time, and the highly specialised nature of polar bears, it is unlikely that polar bears will survive as a species if the sea ice disappears completely as has been predicted by some.

  9. Oceanographic data from five cruises taken in the Barents Sea and Sea of Okhotsk from 19570516 to 19970929 (NCEI Accession 0127526)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bottle/rosette data taken from four Russian vessels in the Sea of Okhotsk and Barents Sea. Data were used for study of the climatic system of Polar Regions.

  10. Extended Hamiltonian approach to continuous tempering.

    Science.gov (United States)

    Gobbo, Gianpaolo; Leimkuhler, Benedict J

    2015-06-01

    We introduce an enhanced sampling simulation technique based on continuous tempering, i.e., on continuously varying the temperature of the system under investigation. Our approach is mathematically straightforward, being based on an extended Hamiltonian formulation in which an auxiliary degree of freedom, determining the effective temperature, is coupled to the physical system. The physical system and its temperature evolve continuously in time according to the equations of motion derived from the extended Hamiltonian. Due to the Hamiltonian structure, it is easy to show that a particular subset of the configurations of the extended system is distributed according to the canonical ensemble for the physical system at the correct physical temperature.

  11. A temperature predictor for parallel tempering simulations.

    Science.gov (United States)

    Patriksson, Alexandra; van der Spoel, David

    2008-04-21

    An algorithm is proposed that generates a set of temperatures for use in parallel tempering simulations (also known as temperature-replica exchange molecular dynamics simulations) of proteins to obtain a desired exchange probability Pdes. The input consists of the number of protein atoms and water molecules in the system, information about the use of constraints and virtual sites and the lower temperature limits. The temperatures generated yield probabilities which are very close to Pdes (correlation 97%), independent of force field and over a wide temperature range. To facilitate its use, the algorithm has been implemented as a web server at .

  12. Land Cover Analysis of Temperate Asia

    Science.gov (United States)

    Justice, Chris

    1998-01-01

    Satellite data from the advanced very high resolution radiometer (AVHRR) instrument were used to produce a general land cover distribution of temperate Asia (referred to hence as Central Asia) from 1982, starting with the NOAA-7 satellite, and continuing through 1991, ending with the NOAA-11 satellite. Emphasis was placed upon delineating the and and semi-arid zones of Central Asia (largely Mongolia and adjacent areas), mapping broad categories of aggregated land cover, and upon studying photosynthetic capacity increases in Central Asia from 1982 to 1991.

  13. Oceanic temperate forest versus warm temperate rainforest: a reply to Grubb et al. (2017)

    DEFF Research Database (Denmark)

    Buitenwerf, Robert

    2017-01-01

    Grubb et al. (2017) point out that we (McGlone et al. 2016) erroneously stated that the definition of warm temperate rain forest (WTRF; Grubb et al. 2013) was based in part on climatic criteria. We apologise: their text made clear that this was not the case. However, they go on to say that they ‘...

  14. Quantification of sea ice production in Weddell Sea polynyas

    Science.gov (United States)

    Zentek, Rolf; Heinemann, Günther; Paul, Stephan; Stulic, Lukrecia; Timmermann, Ralph

    2017-04-01

    The regional climate model COSMO-CLM was used to perform simulations the Weddell Sea region in Antarctica for the time period 2002-2015 with the focus on atmosphere-ocean-sea ice interactions. The original model was adapted to polar regions by the use of a thermodynamic sea ice module with snow cover and an temperature-dependent albedo scheme for sea ice. The recently published topography RTopo2 was used. The model was run with nesting in ERA-Interim data in a forecast mode. Sea ice concentrations were taken from satellite measurements (AMSR-E, SSMI/S, AMSR2) and were updated daily to allow for a close-to-reality hindcast. Simulations were done with 15 km resolution for the whole period 2002-2015 with the goal to force the sea-ice ocean model FESOM. In a second step a 5 km simulation was one-way nested for the winter period (April - September) 2002-2015 to allow for a better quantification of sea ice production in the Weddell Sea. Estimates of sea ice production and comparisons of the results to remote sensing data will be presented.

  15. Assessment of the sea-ice carbon pump

    DEFF Research Database (Denmark)

    Grimm, R.; Notz, D.; Glud, Ronnie N.

    2016-01-01

    It has been suggested that geochemical processes related to sea-ice growth and melt might be important for the polar carbon cycle via the so called sea-ice carbon pump (SICP). The SICP affects the air-sea CO2 exchange by influencing the composition of dissolved inorganic carbon (DIC) and total...

  16. Effects of initial temperature and tempering medium on thermal tempering of dental porcelains.

    Science.gov (United States)

    Hojjatie, B; Anusavice, K J

    1993-03-01

    The objective of this study was to test the hypothesis that quenching of porcelain in silicone oil rather than in compressed air will significantly increase the flexure strength by reducing the potential for crack formation during transient cooling. A secondary hypothesis to be tested is that the initial tempering temperature can be reduced significantly below the porcelain maturing temperature of 982 degrees C but well above Tg without a decrease in strength. Opaque-body porcelain disks, 16 mm in diameter and 2 mm in thickness, with a thermal contraction mismatch (delta alpha) of -1.5, 0, and +3.2 ppm/degrees C were tempered from initial temperatures of 650, 750, 850, and 982 degrees C in silicone oil with kinematic viscosities of 50, 1000, and 5000 centistokes. Porcelain disks were also subjected to three cooling procedures in air: slow cooling in a furnace (SC), free convective cooling in a laboratory bench (FC), and tempering (T) by blasting the surface of body porcelain with air. The crack size induced by a Vickers microhardness indenter was measured within one minute after crack development. For determination of the influence of initial cooling temperature on biaxial flexure strength, six body porcelain disks (delta alpha = 0) were tempered in air from initial temperatures of 650, 750, 850, and 982 degrees C. The mean crack size of specimens tempered in oil was significantly smaller (p < or = 0.001) than that of specimens that were slowly-cooled or fast-cooled in air for all thermal contraction mismatch cases.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Mass Loss Rates of Fasting Polar Bears.

    Science.gov (United States)

    Pilfold, Nicholas W; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E; Lunn, Nicholas J; Richardson, Evan

    2016-01-01

    Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive polar bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009-2014. Polar bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult males was identical to that lost by free-ranging individuals, suggesting that terrestrial feeding contributes little to offset mass loss. The inferred metabolic rate was comparable to a basal mammalian rate, suggesting that while on land, polar bears can maintain a depressed metabolic rate to conserve energy. Finally, we estimated time to starvation for subadults and adult males for the on-land period. Results suggest that at 180 d of fasting, 56%-63% of subadults and 18%-24% of adult males in this study would die of starvation. Results corroborate previous assessments on the limits of polar bear capacity to withstand lengthening ice-free seasons and emphasize the greater sensitivity of subadults to changes in sea ice phenology.

  18. Could the acid-base status of Antarctic sea urchins indicate a better-than-expected resilience to near-future ocean acidification?

    Science.gov (United States)

    Collard, Marie; De Ridder, Chantal; David, Bruno; Dehairs, Frank; Dubois, Philippe

    2015-02-01

    Increasing atmospheric carbon dioxide concentration alters the chemistry of the oceans towards more acidic conditions. Polar oceans are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the oceans' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to ocean acidification in metazoans is first linked to acid-base regulation capacities of the extracellular fluids. No information on this is available to date for Antarctic echinoderms and inference from temperate and tropical studies needs support. In this study, we investigated the acid-base status of 9 species of sea urchins (3 cidaroids, 2 regular euechinoids and 4 irregular echinoids). It appears that Antarctic regular euechinoids seem equipped with similar acid-base regulation systems as tropical and temperate regular euechinoids but could rely on more passive ion transfer systems, minimizing energy requirements. Cidaroids have an acid-base status similar to that of tropical cidaroids. Therefore Antarctic cidaroids will most probably not be affected by decreasing seawater pH, the pH drop linked to ocean acidification being negligible in comparison of the naturally low pH of the coelomic fluid. Irregular echinoids might not suffer from reduced seawater pH if acidosis of the coelomic fluid pH does not occur but more data on their acid-base regulation are needed. Combining these results with the resilience of Antarctic sea urchin larvae strongly suggests that these organisms might not be the expected victims of ocean acidification. However, data on the impact of other global stressors such as temperature and of the combination of the different stressors needs to be acquired to assess the sensitivity of these organisms to global

  19. Not-so-well-tempered neutralino

    Science.gov (United States)

    Profumo, Stefano; Stefaniak, Tim; Stephenson-Haskins, Laurel

    2017-09-01

    Light electroweakinos, the neutral and charged fermionic supersymmetric partners of the standard model SU (2 )×U (1 ) gauge bosons and of the two SU(2) Higgs doublets, are an important target for searches for new physics with the Large Hadron Collider (LHC). However, if the lightest neutralino is the dark matter, constraints from direct dark matter detection experiments rule out large swaths of the parameter space accessible to the LHC, including in large part the so-called "well-tempered" neutralinos. We focus on the minimal supersymmetric standard model (MSSM) and explore in detail which regions of parameter space are not excluded by null results from direct dark matter detection, assuming exclusive thermal production of neutralinos in the early universe, and illustrate the complementarity with current and future LHC searches for electroweak gauginos. We consider both bino-Higgsino and bino-wino "not-so-well-tempered" neutralinos, i.e. we include models where the lightest neutralino constitutes only part of the cosmological dark matter, with the consequent suppression of the constraints from direct and indirect dark matter searches.

  20. Climatology and Genesis Environment of North Atlantic Polar Lows

    Science.gov (United States)

    Michel, Clio; Spengler, Thomas

    2016-04-01

    Polar lows are intense maritime cyclones occurring during cold air outbreaks in high latitudes. We use the Melbourne University cyclone algorithm to detect and track polar lows. The algorithm employs the Laplacian of mean sea level pressure and is applied to the ERA-Interim reanalyses from 1979 to 2014. Track density maps indicate that polar lows mainly occur close to Svalbard, as well as in the northern Norwegian Sea and the Barents Sea. This is in accordance to previous studies about polar low tracks densities which are using less objective method and shorter time periods. Also the cyclogenesis density correlates well with the winter-time climatology of cold air outbreaks. Furthermore, we present inter- and intra-annual variability of polar lows and its relation to the NAO as well as sea ice extent. We also differentiated the polar low genesis environment into forward and reverse shear conditions, where forward shear implies that the thermal and mean wind are in the same direction, whereas they are opposite for reverse shear conditions. The forward and reverse shear results based on the objective tracking are similar to a previous study based on polar low tracks from the STARS data set provided by MET Norway.

  1. An Integrated Time-Temperature Approach for Predicting Mechanical Properties of Quenched and Tempered Steels

    OpenAIRE

    O'Connell, Corey James

    2014-01-01

    The purpose of this work was to develop a steel tempering model that is useful to the commercial heat treater. Most of the tempering models reported address isothermal conditions which are not typical of most heating methods used to perform the tempering heat treatment. In this work, a non-isothermal tempering model was developed based on the tempering response of four steel alloys. This tempering model employs the quantity resulting from the numerical integration of the time-temperature prof...

  2. The tempering quality evaluation of cocoa liquor during industrial ...

    African Journals Online (AJOL)

    The tempering quality evaluation of the crude cocoa liquor with average fat content 55.0 ± 0.3 % and an average acid value, 1.57 ± 0.34) has been established. The various parameters considered were recasting time (RT) and appearance (AP) of the tempered product on one hand and the flow (F) of the crude liquor on ...

  3. Spray mist cooling heat transfer in glass tempering process

    Science.gov (United States)

    Sozbir, Nedim; Yao, S. C.

    2017-05-01

    Energy saving is a very important issue in glass plants, especially in a glass tempering process, where very high velocity air jet impingement is applied during the cooling process of glass tempering. In fact, air compressor energy may be reduced by a spray cooling due to its high heat transfer capabilities. Presently, in this paper, both pure air and water mist spray cooling are investigated in the glass tempering process. The test results indicate that thin and low-cost tempered glass can be made by mist cooling without fracture. It is possible to find the optimal water flux and duration of mist application to achieve a desirable temperature distribution in the glass for deep penetration of the cooling front but without inducing cracking during the tempering. The use of mist cooling could give about 29 % air pressure reduction for 2-mm glass plate and 50 % reduction for both 3- and 4-mm glass plates.

  4. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  5. Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone: I. Selective preservation and degradation in the water column and consequences for the TEX

    NARCIS (Netherlands)

    Schouten, S.; Pitcher, A.; Hopmans, E.C.; Villanueva, L.; van Bleijswijk, J.; Sinninghe Damsté, J.S.

    2012-01-01

    Glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) have proven to be important biomarker lipids for specific archaeal lineages and their distribution is used as a paleotemperature proxy. In this study, we analyzed GDGTs in suspended particles in the water column of the Arabian Sea at different

  6. Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone: I. Selective preservation and degradation in the water column and its consequences for the TEX86

    NARCIS (Netherlands)

    Schouten, S.; Pitcher, A.; Hopmans, E.C.; Villaneuva, L.; Bleijswijk, J. van; Sinninghe Damsté, J.S.

    2012-01-01

    Glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) have proven to be important biomarker lipids for specific archaeal lineages and their distribution is used as a paleotemperature proxy. In this study, we analyzed GDGTs in suspended particles in the water column of the Arabian Sea at

  7. Climate change, sea ice, and RADARSAT

    Energy Technology Data Exchange (ETDEWEB)

    Barber, D.G. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Geography

    1998-12-31

    The role of sea ice in climate variability and change was discussed. It was suggested that since oceanic and atmospheric circulation patterns are driven by polar processes, sea ice is a good potential indicator of the impacts of climate variability and change. Sensors such as RADARSAT are ideal for direct measurement and monitoring of the effects of climate change in polar regions. This presentation described the nature of the surface energy balance over sea ice and described how energy fluxes affect both the geophysical and electrical properties of sea ice over the annual cycle of growth and decay. The concept of the time series evolution in the average relative scattering coefficient as a means of directly measuring the thermodynamic state of the ocean-sea ice-atmosphere system was introduced. Work recently completed in the North Water Polynya study, the Collaborative Interdisciplinary Cryosphere Experiment (C-ICE), and the Surface Heat and Energy Balance of the Arctic (SHEBA) was also described.

  8. Kinship analyses identify fish dispersal events on a temperate coastline.

    Science.gov (United States)

    Schunter, C; Pascual, M; Garza, J C; Raventos, N; Macpherson, E

    2014-06-22

    Connectivity is crucial for the persistence and resilience of marine species, the establishment of networks of marine protected areas and the delineation of fishery management units. In the marine environment, understanding connectivity is still a major challenge, due to the technical difficulties of tracking larvae. Recently, parentage analysis has provided a means to address this question effectively. To be effective, this method requires limited adult movement and extensive sampling of parents, which is often not possible for marine species. An alternative approach that is less sensitive to constraints in parental movement and sampling could be the reconstruction of sibships. Here, we directly measure connectivity and larval dispersal in a temperate marine ecosystem through both analytical approaches. We use data from 178 single nucleotide polymorphism markers to perform parentage and sibship reconstruction of the black-faced blenny (Tripterygion delaisi) from an open coastline in the Mediterranean Sea. Parentage analysis revealed a decrease in dispersal success in the focal area over 1 km distance and approximately 6.5% of the juveniles were identified as self-recruits. Sibship reconstruction analysis found that, in general, full siblings did not recruit together to the same location, and that the largest distance between recruitment locations was much higher (11.5 km) than found for parent-offspring pairs (1.2 km). Direct measurements of dispersal are essential to understanding connectivity patterns in different marine habitats, and show the degree of self-replenishment and sustainability of populations of marine organisms. We demonstrate that sibship reconstruction allows direct measurements of dispersal and family structure in marine species while being more easily applied in those species for which the collection of the parental population is difficult or unfeasible.

  9. A New Remotely Operated Sensor Platform for Interdisciplinary Observations under Sea Ice

    OpenAIRE

    Katlein, Christian; Schiller, Martin; Belter, Hans J.; Coppolaro, Veronica; Wenslandt, David; Nicolaus, Marcel

    2017-01-01

    Observation of the climate and ecosystem of ice covered polar seas is a timely task for the scientific community. The goal is to assess the drastic and imminent changes of the polar sea ice cover induced by climate change. Retreating and thinning sea ice affects the planets energy budget, atmospheric, and oceanic circulation patterns as well as the ecosystem associated with this unique habitat. To increase the observational capabilities of sea ice scientists, we equipped a remotely operated v...

  10. Temperate Ice Depth-Sounding Radar

    Science.gov (United States)

    Jara-Olivares, V. A.; Player, K.; Rodriguez-Morales, F.; Gogineni, P.

    2008-12-01

    Glaciers in several parts of the world are reported to be retreating and thinning rapidly over the last decade. Radar instruments can be used to provide a wealth of information regarding the internal and basal conditions of large and small ice masses. These instruments typically operate in the VHF and UHF regions of the electromagnetic spectrum. For temperate-ice sounding, however, the high water content produces scattering and attenuation in propagating radar waves at VHF and UHF frequencies, which significantly reduce the penetration depths. Radars operating in the HF band are better suited for systematic surveys of the thickness and sub-glacial topography of temperate-ice regions. We are developing a dual-frequency Temperate-Ice-Depth Sounding Radar (TIDSoR) that can penetrate through water pockets, thus providing more accurate measurements of temperate ice properties such as thickness and basal conditions. The radar is a light-weight, low power consumption portable system for surface-based observations in mountainous terrain or aerial surveys. TIDSoR operates at two different center frequencies: 7.7 MHz and 14 MHz, with a maximum output peak power of 20 W. The transmit waveform is a digitally generated linear frequency-modulated chirp with 1 MHz bandwidth. The radar can be installed on aircrafts such as the CReSIS UAV [1], DCH-6 (Twin Otter), or P-3 Orion for aerial surveys, where it could be supported by the airplane power system. For surface based experiments, TIDSoR can operate in a backpack configuration powered by a compact battery system. The system can also be installed on a sled towed by a motorized vehicle, in which case the power supply can be replaced by a diesel generator. The radar consists of three functional blocks: the digital section, the radio-frequency (RF) section, and the antenna, and is designed to weigh less than 2 kg, excluding the power supply. The digital section generates the transmit waveforms as well as timing and control signals

  11. Moist temperate forest butterflies of western Bhutan

    Directory of Open Access Journals (Sweden)

    Arun P. Singh

    2016-03-01

    Full Text Available Random surveys were carried out in moist temperate forests (1,860–3,116 m around Bunakha Village and Dochula Pass, near Thimphu in western Bhutan, recording 65 species of butterflies.  Of these, 11 species, viz., Straightwing Blue Orthomiella pontis pontis Elwes, Slate Royal Maneca bhotea bhotea Moore, Dull Green Hairstreak Esakiozephyrus icana Moore, Yellow Woodbrown Lethe nicetas Hewitson, Small Silverfork Zophoessa jalaurida elwesi Moore, Scarce Labyrinth, Neope pulahina (Evans, Chumbi Wall Chonala masoni Elwes, Pale Hockeystick Sailer Neptis manasa manasa Moore and White Commodore Parasarpa dudu dudu Westwood, are restricted to the eastern Himalaya, northeastern India and Myanmar.  Two other species, Tawny Mime Chiasa agestor agestor (Gray and Himalayan Spotted Flat Celaenorrhinus munda Moore have been only rarely recorded from Bhutan and a few individuals of the rare Bhutan Glory Bhutanitis lidderdalei Atkinson were also recorded near Bunakha.  

  12. Study on tempering behaviour of AISI 410 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Gopa, E-mail: gopa_mjs@igcar.gov.in [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V. [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Panneerselvam, G. [Chemistry Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Dasgupta, Arup [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India)

    2015-02-15

    Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M{sub 23}C{sub 6}) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe{sub 2}C and M{sub 23}C{sub 6} types of carbides coexisting in the material. The nucleation of Fe{sub 2}C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M{sub 23}C{sub 6} carbides, instead of Fe{sub 2}C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of

  13. Forecasting cyanobacteria dominance in Canadian temperate lakes.

    Science.gov (United States)

    Persaud, Anurani D; Paterson, Andrew M; Dillon, Peter J; Winter, Jennifer G; Palmer, Michelle; Somers, Keith M

    2015-03-15

    Predictive models based on broad scale, spatial surveys typically identify nutrients and climate as the most important predictors of cyanobacteria abundance; however these models generally have low predictive power because at smaller geographic scales numerous other factors may be equally or more important. At the lake level, for example, the ability to forecast cyanobacteria dominance is of tremendous value to lake managers as they can use such models to communicate exposure risks associated with recreational and drinking water use, and possible exposure to algal toxins, in advance of bloom occurrence. We used detailed algal, limnological and meteorological data from two temperate lakes in south-central Ontario, Canada to determine the factors that are closely linked to cyanobacteria dominance, and to develop easy to use models to forecast cyanobacteria biovolume. For Brandy Lake (BL), the strongest and most parsimonious model for forecasting % cyanobacteria biovolume (% CB) included water column stability, hypolimnetic TP, and % cyanobacteria biovolume two weeks prior. For Three Mile Lake (TML), the best model for forecasting % CB included water column stability, hypolimnetic TP concentration, and 7-d mean wind speed. The models for forecasting % CB in BL and TML are fundamentally different in their lag periods (BL = lag 1 model and TML = lag 2 model) and in some predictor variables despite the close proximity of the study lakes. We speculate that three main factors (nutrient concentrations, water transparency and lake morphometry) may have contributed to differences in the models developed, and may account for variation observed in models derived from large spatial surveys. Our results illustrate that while forecast models can be developed to determine when cyanobacteria will dominate within two temperate lakes, the models require detailed, lake-specific calibration to be effective as risk-management tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Phosphorous dynamics in a temperate intertidal estuary

    Science.gov (United States)

    Lillebø, A. I.; Neto, J. M.; Flindt, M. R.; Marques, J. C.; Pardal, M. A.

    2004-09-01

    Conservation and management of aquatic systems require detailed information of the processes that affect their functioning and development. The objectives of the present work were to describe the phosphorus dynamics during a complete tidal cycle and to quantify the relative contribution of the most common estuarine areas (e.g. seagrass beds, salt marshes, mud- and sand-flats without vegetation) to phosphorus net internal loading in a temperate intertidal estuary. Results show that phosphate efflux rates were higher during the first hours of tidal flood, and that phosphate concentrations were lowest at high tide. During tidal ebbing, ephemeral tide pools may cover a considerable percentage of the intertidal area. In these tide pools, water shallowness combined with enhanced temperatures stimulate the occurrence of high phosphate effluxes. The effluxes to the main water body during high tide contributed 57% of dissolved inorganic phosphorus and efflux during low tide contributed 43% to the net internal loading. Calculations of the phosphate net effluxes (kg P) indicate a strong contribution of the bare bottom mud-flats to the whole system internal phosphate loading, especially during the warmer periods. As a consequence of eutrophication, perennial benthic macrophytes are commonly replaced by fast-growing epiphytic macroalgae. Calculations showed that for a hypothetical intertidal estuary in a temperate region, management programs considering an eventual re-colonization of mud-flats by seagrasses or salt marsh plants may reduce the P-efflux by 13-16 kg ha -1. For example, in the small Mondego estuary, eutrophication has contributed to a reduction of the Zostera noltii meadows, leading to an increase in 190 kg of phosphorus net internal loading.

  15. Phenology of temperate trees in tropical climates

    Science.gov (United States)

    Borchert, Rolf; Robertson, Kevin; Schwartz, Mark D.; Williams-Linera, Guadalupe

    2005-09-01

    Several North American broad-leaved tree species range from the northern United States at ˜47°N to moist tropical montane forests in Mexico and Central America at 15-20°N. Along this gradient the average minimum temperatures of the coldest month (T Jan), which characterize annual variation in temperature, increase from -10 to 12°C and tree phenology changes from deciduous to leaf-exchanging or evergreen in the southern range with a year-long growing season. Between 30 and 45°N, the time of bud break is highly correlated with T Jan and bud break can be reliably predicted for the week in which mean minimum temperature rises to 7°C. Temperature-dependent deciduous phenology—and hence the validity of temperature-driven phenology models—terminates in southern North America near 30°N, where T Jan>7°C enables growth of tropical trees and cultivation of frost-sensitive citrus fruits. In tropical climates most temperate broad-leaved species exchange old for new leaves within a few weeks in January-February, i.e., their phenology becomes similar to that of tropical leaf-exchanging species. Leaf buds of the southern ecotypes of these temperate species are therefore not winter-dormant and have no chilling requirement. As in many tropical trees, bud break of Celtis, Quercus and Fagus growing in warm climates is induced in early spring by increasing daylength. In tropical climates vegetative phenology is determined mainly by leaf longevity, seasonal variation in water stress and day length. As water stress during the dry season varies widely with soil water storage, climate-driven models cannot predict tree phenology in the tropics and tropical tree phenology does not constitute a useful indicator of global warming.

  16. Arctic tides from GPS on sea ice

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing...... of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic. The GPS measurements are compared with the Arctic tidal model AOTIM-5, which assimilates tide...

  17. Population substructure and space use of Foxe Basin polar bears.

    Science.gov (United States)

    Sahanatien, Vicki; Peacock, Elizabeth; Derocher, Andrew E

    2015-07-01

    Climate change has been identified as a major driver of habitat change, particularly for sea ice-dependent species such as the polar bear (Ursus maritimus). Population structure and space use of polar bears have been challenging to quantify because of their circumpolar distribution and tendency to range over large areas. Knowledge of movement patterns, home range, and habitat is needed for conservation and management. This is the first study to examine the spatial ecology of polar bears in the Foxe Basin management unit of Nunavut, Canada. Foxe Basin is in the mid-Arctic, part of the seasonal sea ice ecoregion and it is being negatively affected by climate change. Our objectives were to examine intrapopulation spatial structure, to determine movement patterns, and to consider how polar bear movements may respond to changing sea ice habitat conditions. Hierarchical and fuzzy cluster analyses were used to assess intrapopulation spatial structure of geographic position system satellite-collared female polar bears. Seasonal and annual movement metrics (home range, movement rates, time on ice) and home-range fidelity (static and dynamic overlap) were compared to examine the influence of regional sea ice on movements. The polar bears were distributed in three spatial clusters, and there were differences in the movement metrics between clusters that may reflect sea ice habitat conditions. Within the clusters, bears moved independently of each other. Annual and seasonal home-range fidelity was observed, and the bears used two movement patterns: on-ice range residency and annual migration. We predict that home-range fidelity may decline as the spatial and temporal predictability of sea ice changes. These new findings also provide baseline information for managing and monitoring this polar bear population.

  18. Implications of rapid environmental change for polar bear behavior and sociality

    Science.gov (United States)

    Atwood, Todd C.

    2017-01-01

    Historically, the Arctic sea ice has functioned as a structural barrier that has limited the nature and extent of interactions between humans and polar bears (Ursus maritimus). However, declining sea ice extent, brought about by global climate change, is increasing the potential for human-polar bear interactions. Loss of sea ice habitat is driving changes to both human and polar bear behavior—it is facilitating increases in human activities (e.g., offshore oil and gas exploration and extraction, trans-Arctic shipping, recreation), while also causing the displacement of bears from preferred foraging habitat (i.e., sea ice over biologically productive shallow) to land in some portions of their range. The end result of these changes is that polar bears are spending greater amounts of time in close proximity to people. Coexistence between humans and polar bears will require imposing mechanisms to manage further development, as well as mitigation strategies that reduce the burden to local communities.

  19. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...... inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  20. Polar bear management in Alaska 1997-2000

    Science.gov (United States)

    Schliebe, Scott L.; Bridges, John W.; Evans, Thomas J.; Fischbach, Anthony S.; Kalxdorff, Susanne B.; Lierheimer, Lisa J.; Lunn, Nicholas J.; Schliebe, Scott L.; Born, Erik W.; Lunn, Nicholas J.; Schliebe, Scott L.; Born, Erik W.

    2002-01-01

    Since the Twelfth Working Meeting of the IUCN/SSC Polar Bear Specialist Group in 1997, a number of changes in the management of polar bears have occurred in Alaska. On October 16, 2000, the governments of the United States and the Russian Federation signed the “Agreement on the Conservation and Management of the Alaska-Chukotka Polar Bear Population.” This agreement provides substantial benefits for the effective conservation of polar bears shared between the U.S. and Russia. It will require enactment of enabling legislation by the U.S. Congress and other steps by Russia before the agreement has the force of law. A copy of the agreement is included as Appendix 1 to this report. Also, during this period, regulations were developed to implement 1994 amendments to the Marine Mammal Protection Act (MMPA), which allow polar bear trophies taken in approved Canadian populations by U.S. citizens to be imported into the U.S. A summary of the regulatory actions and a table listing populations approved for importation and the number of polar bears imported into the U.S. since 1997 is included in this report. Regarding oil and gas activities in polar bear habitat, three sets of regulations were published authorizing the incidental, non-intentional, taking of small numbers of polar bears concurrent to oil and gas activities.Cooperation continued with the Alaska Nanuuq Commission, representing the polar bear hunting communities in Alaska, as well as with the North Slope Borough and the Inuvialuit Game Council in their agreement for the management of the Southern Beaufort Sea polar bear population. Harvest summaries and technical assistance in designing and assistance in conducting a National Park Service/Alaska Nanuuq Commission study to collect traditional ecological knowledge of polar bear habitat use in Chukotka were provided. In addition, a long-range plan was developed to address and minimize polar bear-human conflicts in North Slope communities.We continued to monitor

  1. Stress relaxation in tempered glass caused by heat soak testing

    DEFF Research Database (Denmark)

    Schneider, Jens; Hilcken, Jonas; Aronen, Antti

    2016-01-01

    of commercial soda-lime-silica glass, it causes stress relaxation in tempered glass and the fracture pattern of the glass changes accordingly, especially thin glasses are affected. Based on the Tool-Narayanaswamy-Model, this paper comprises the theoretical background of the stress......Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so...

  2. First Evidence of an Important Organic Matter Trophic Pathway between Temperate Corals and Pelagic Microbial Communities.

    Science.gov (United States)

    Fonvielle, J A; Reynaud, S; Jacquet, S; LeBerre, B; Ferrier-Pages, C

    2015-01-01

    Mucus, i.e., particulate and dissolved organic matter (POM, DOM) released by corals, acts as an important energy carrier in tropical ecosystems, but little is known on its ecological role in temperate environments. This study assessed POM and DOM production by the temperate coral Cladocora caespitosa under different environmental conditions. The subsequent enzymatic degradation, growth of prokaryotes and virus-like particles (VLPs) as well as changes in the structure of the prokaryotic communities were also monitored. C. caespitosa produced an important quantity of mucus, which varied according to the environmental conditions (from 37.8 to 67.75 nmol carbon h-1 cm-2), but remained higher or comparable to productions observed in tropical corals. It has an important nutritional value, as highlighted by the high content in dissolved nitrogen (50% to 90% of the organic matter released). Organic matter was rapidly degraded by prokaryotes' enzymatic activities, and due to its nitrogen content, aminopeptidase activity was 500 fold higher than the α-glucosidase activity. Prokaryotes, as well as VLPs, presented a rapid growth in the mucus, with prokaryote production rates as high as 0.31 μg h-1 L-1. Changes in bacterial and archaeal communities were observed in the ageing mucus and between mucus and the water column, suggesting a clear impact of mucus on microorganism diversity. Overall, our results show that the organic matter released by temperate corals, such as C. caespitosa, which can form reef structures in the Mediterranean Sea, stimulates microbial activity and thereby functions as a significant carbon and nitrogen supplier to the microbial loop.

  3. First Evidence of an Important Organic Matter Trophic Pathway between Temperate Corals and Pelagic Microbial Communities.

    Directory of Open Access Journals (Sweden)

    J A Fonvielle

    Full Text Available Mucus, i.e., particulate and dissolved organic matter (POM, DOM released by corals, acts as an important energy carrier in tropical ecosystems, but little is known on its ecological role in temperate environments. This study assessed POM and DOM production by the temperate coral Cladocora caespitosa under different environmental conditions. The subsequent enzymatic degradation, growth of prokaryotes and virus-like particles (VLPs as well as changes in the structure of the prokaryotic communities were also monitored. C. caespitosa produced an important quantity of mucus, which varied according to the environmental conditions (from 37.8 to 67.75 nmol carbon h-1 cm-2, but remained higher or comparable to productions observed in tropical corals. It has an important nutritional value, as highlighted by the high content in dissolved nitrogen (50% to 90% of the organic matter released. Organic matter was rapidly degraded by prokaryotes' enzymatic activities, and due to its nitrogen content, aminopeptidase activity was 500 fold higher than the α-glucosidase activity. Prokaryotes, as well as VLPs, presented a rapid growth in the mucus, with prokaryote production rates as high as 0.31 μg h-1 L-1. Changes in bacterial and archaeal communities were observed in the ageing mucus and between mucus and the water column, suggesting a clear impact of mucus on microorganism diversity. Overall, our results show that the organic matter released by temperate corals, such as C. caespitosa, which can form reef structures in the Mediterranean Sea, stimulates microbial activity and thereby functions as a significant carbon and nitrogen supplier to the microbial loop.

  4. Drilling in tempered glass – modelling and experiments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    The present paper reports experimentally and numerically obtained results for the process of drilling in tempered glass. The experimental results are drilling depths on the edge in 19mm tempered glass with a known residual stress state measured by a scattered light polariscope. The experiments have...... been modelled using a state-of-the-art model and compared with satisfying result to the performed experiments. The numerical model has been used for a parametric study, investigating the redistribution of residual stresses during the process of drilling. This is done for investigating the possibility...... of applying forces in such holes and thereby being able to mechanically assemble tempered glass without the need of drilling holes before the tempering process. The paper is the result of currently ongoing research and the results should be treated as so....

  5. Graphing Polar Curves

    Science.gov (United States)

    Lawes, Jonathan F.

    2013-01-01

    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  6. Error and efficiency of simulated tempering simulations.

    Science.gov (United States)

    Rosta, Edina; Hummer, Gerhard

    2010-01-21

    We derive simple analytical expressions for the error and computational efficiency of simulated tempering (ST) simulations. The theory applies to the important case of systems whose dynamics at long times is dominated by the slow interconversion between two metastable states. An extension to the multistate case is described. We show that the relative gain in efficiency of ST simulations over regular molecular dynamics (MD) or Monte Carlo (MC) simulations is given by the ratio of their reactive fluxes, i.e., the number of transitions between the two states summed over all ST temperatures divided by the number of transitions at the single temperature of the MD or MC simulation. This relation for the efficiency is derived for the limit in which changes in the ST temperature are fast compared to the two-state transitions. In this limit, ST is most efficient. Our expression for the maximum efficiency gain of ST simulations is essentially identical to the corresponding expression derived by us for replica exchange MD and MC simulations [E. Rosta and G. Hummer, J. Chem. Phys. 131, 165102 (2009)] on a different route. We find quantitative agreement between predicted and observed efficiency gains in a test against ST and replica exchange MC simulations of a two-dimensional Ising model. Based on the efficiency formula, we provide recommendations for the optimal choice of ST simulation parameters, in particular, the range and number of temperatures, and the frequency of attempted temperature changes.

  7. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  8. Crenarchaeota and Euryarchaeota in temperate estuarine sediments.

    Science.gov (United States)

    Abreu, C; Jurgens, G; De Marco, P; Saano, A; Bordalo, A A

    2001-05-01

    Application of molecular techniques to ecological studies has unveiled a wide diversity of micro-organisms in natural communities, previously unknown to microbial ecologists. New lineages of Archaea were retrieved from several non-extreme environments, showing that these micro-organisms are present in a large variety of ecosystems. The aim was therefore to assess the presence and diversity of Archaea in the sediments of the river Douro estuary (Portugal), relating the results obtained to ecological data. Total DNA was extracted from sediment samples obtained from an estuary deprived of vegetation, amplified by PCR and the resulting DNA fragments cloned. The archaeal origin of the cloned inserts was checked by Southern blot, dot blot or colony blot hybridization. Recombinant plasmids were further analysed by restriction with AvaII and selected for sequencing. Phylogenetic analyses of 14 sequences revealed the presence of members of the domain Archaea. Most of the sequences could be assigned to the kingdom Crenarchaeota. Most of these sequences were closely related to those obtained from non-extreme Crenarchaeota members previously retrieved from diverse ecosystems, such as freshwater and marine environments. The presence of archaeal 16S rDNA sequences in temperate estuarine sediments emerges as a valuable contribution to the understanding of the complexity of the ecosystem.

  9. 2014 NSF Workshop on High-Performance Distributed Computing in Polar Science. Draft Polar HPDC Cyberinfrastructure Report. December 4-5, New Brunswick, NJ:

    OpenAIRE

    Shantenu Jha; Lynn Yarmey

    2015-01-01

    Climate change in the 20th and 21st century is dramatically changing the polar regions. This is documented by numerous studies, for example as thawing permafrost, retreating Arctic sea ice and accelerating mass loss from glaciers and ice sheets. These changes may have widespread consequences for many aspects of the earth systems, e.g. carbon budget, food and water security, sea levels, and freshwater input to oceans. To understand the changing polar regions and their global impacts, scientist...

  10. Influence of tempering temperature on mechanical properties of cast steels

    Directory of Open Access Journals (Sweden)

    G. Golański

    2008-12-01

    Full Text Available The paper presents results of research on the influence of tempering temperature on structure and mechanical properties of bainite hardened cast steel: G21CrMoV4 – 6 (L21HMF and G17CrMoV5 – 10 (L17HMF. Investigated cast steels were taken out from internal frames of steam turbines serviced for long time at elevated temperatures. Tempering of the investigated cast steel was carried out within the temperature range of 690 ÷ 730 C (G21CrMoV4 – 6 and 700 ÷ 740 C (G17CrMoV5 – 10. After tempering the cast steels were characterized by a structure of tempered lower bainite with numerous precipitations of carbides. Performed research of mechanical properties has shown that high temperatures of tempering of bainitic structure do not cause decrease of mechanical properties beneath the required minimum.oo It has also been proved that high-temperature tempering (>720 oC ensures high impact energy at the 20% decrease of mechanical properties.

  11. Dung beetle communities: a neotropical-north temperate comparison.

    Science.gov (United States)

    Radtke, Meghan G; Fonseca, Cláudio R V da; Williamson, G Bruce

    2010-01-01

    Dung beetle communities have been compared across north temperate latitudes. Tropical dung beetle communities appear to be more diverse based on studies using different methodologies. Here, we present results from a standardized sampling protocol used to compare dung beetle communities across five neotropical forests in Brazil and Ecuador and two warm, north temperate forests in Mississippi and Louisiana. Species richness in the tropical forests was three to seven times higher than the temperate forests, as would be expected by studies of other taxa across tropical and temperate latitudes. Average body size in the temperate forests was larger than the tropical forests, as predicted by Bergmann's rule. Dung beetle abundance and volume per trap-day were generally higher in Ecuador than Brazil, and higher in Mississippi than Louisiana, but there were no tropical-temperate differences. Species rank-abundance curves were similar within countries and between countries. Rank-volume distributions indicated a smaller range of beetle body sizes in Ecuador versus Brazil or the USA. Community similarity was high within countries and low between countries. Community differences between Brazil and Ecuador sites may be explained by differences in productivity based on geological age of the soils.

  12. Restoration of a boulder reef in temperate waters: Strategy, methodology and lessons learnt

    DEFF Research Database (Denmark)

    Støttrup, Josianne Gatt; Dahl, Karsten; Niemann, Sanne

    2017-01-01

    and geotechnical surveys confirmed that the sea bed could support added boulders, and high resolution bathymetric surveys provided input for the design of the reef, particularly for numerical modelling of the hydrographic and sediment transport conditions. Numerical modelling was used to derive hydrographic design......Anthropogenic impacts on marine habitats are a global problem, particularly in coastal areas. While boulder reefs in temperate waters hold high biomass and biodiversity, and may be unable to recover from anthropogenic stressors without restoration efforts, little is known about how to restore......, collected in 2009, demonstrated that cavernous structures and shallow reef areas were restored. Moreover, data collected in 2012 confirmed the stability of the restored reef. Finally, results highlighted the importance of stakeholder mapping at the outset, appropriate timing of stakeholder involvement...

  13. A Future Polarized Drell-Yan Experiment at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Kleinjan, David William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-04

    The topic is treated in a series of slides under the following headings: Motivation (Nucleon Spin Puzzle, Quark Orbital Momentum and the Sivers Function, Accessing Sivers via Polarized Drell-Yan (p+p↑ → μ+μ-)); Transition of Seaquest (E906 → E1039) (Building a Polarized proton Target, Status of Polarized Target); and Outlook. The nucleon spin puzzle: when the quark and gluon contributions to the proton spin are evaluated, nearly 50% of the measured spin is missing; lattice QCD calculations indicate as much as 50% may come from quark orbital angular momentum. Sea quarks should carry orbital angular momentum (O.A.M.). The E1039 Polarized Target Drell-Yan Experiment provides opportunity to study possible Sea Quark O.A.M. Data taking is expected to begin in the spring of 2017.

  14. On the potential application of polar and temperate marine microalgae for EPA and DHA production

    NARCIS (Netherlands)

    Boelen, P.; van Dijk, R.; Sinninghe Damsté, J.S.; Rijpstra, W.I.C.; Buma, A.G.J.

    2013-01-01

    Long chain polyunsaturated fatty acids (LC-PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are considered essential omega-3 fatty acids in human nutrition. In marine microalgae EPA and/or DHA are allegedly involved in the regulation of membrane fluidity and thylakoid

  15. Sea ice biogeochemistry: a guide for modellers.

    Directory of Open Access Journals (Sweden)

    Letizia Tedesco

    Full Text Available Sea ice is a fundamental component of the climate system and plays a key role in polar trophic food webs. Nonetheless sea ice biogeochemical dynamics at large temporal and spatial scales are still rarely described. Numerical models may potentially contribute integrating among sparse observations, but available models of sea ice biogeochemistry are still scarce, whether their relevance for properly describing the current and future state of the polar oceans has been recently addressed. A general methodology to develop a sea ice biogeochemical model is presented, deriving it from an existing validated model application by extension of generic pelagic biogeochemistry model parameterizations. The described methodology is flexible and considers different levels of ecosystem complexity and vertical representation, while adopting a strategy of coupling that ensures mass conservation. We show how to apply this methodology step by step by building an intermediate complexity model from a published realistic application and applying it to analyze theoretically a typical season of first-year sea ice in the Arctic, the one currently needing the most urgent understanding. The aim is to (1 introduce sea ice biogeochemistry and address its relevance to ocean modelers of polar regions, supporting them in adding a new sea ice component to their modelling framework for a more adequate representation of the sea ice-covered ocean ecosystem as a whole, and (2 extend our knowledge on the relevant controlling factors of sea ice algal production, showing that beyond the light and nutrient availability, the duration of the sea ice season may play a key-role shaping the algal production during the on going and upcoming projected changes.

  16. Sodium, Iodine and Bromine in Polar Ice Cores

    DEFF Research Database (Denmark)

    Maffezzoli, Niccolo

    back trajectory analyses of the past 17 years. The results identify the aerosol source area influencing the Renland ice cap, a result necessary for the interpretation of impurity records obtained from the ice core. Chapter 6 reviews the published ice/snow measurements of bromine and iodine at polar......Abstract: This research focuses on sodium, bromine and iodine in polar ice cores, with the aim of reviewing and advancing their current understanding with additional measurements and records, and investigating the connections of these tracers with sea ice and their feasibility as sea ice indicators....... Modern Arctic sea ice decline clearly yields further motivation in this direction, as the reconstruction of past sea ice conditions could provide clues to the mechanisms in play nowadays and in the future projections. Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) has been applied...

  17. A circumpolar monitoring framework for polar bears

    Science.gov (United States)

    Vongraven, Dag; Aars, Jon; Amstrup, Steven C.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Michael J.; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

    2012-01-01

    Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

  18. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.

    1981-01-01

    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  19. Northern Sand Sea

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form. This VIS image was taken at 82 degrees North latitude during Northern spring. The image is completely dominated by dunes. In sand seas, it is very common for a single type of dune to occur, and for a single predominate wind to control the alignment of the dunes. Image information: VIS instrument. Latitude 82.2, Longitude 152.5 East (207.5 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Sea-ice thickness from airborne laser altimetry over the Arctic Ocean north of Greenland

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Forsberg, René

    2002-01-01

    We present a new method to measure ice thickness of polar sea-ice freeboard heights, using airborne laser altimetry combined with a precise geoid model, giving estimates of thickness of ice through isostatic equilibrium assumptions. In the paper we analyze a number of flights from the Polar Sea off...

  1. Flooded! An Investigation of Sea-Level Rise in a Changing Climate

    Science.gov (United States)

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    Explore how melting ice sheets affect global sea levels. Sea-level rise (SLR) is a rise in the water level of the Earth's oceans. There are two major kinds of ice in the polar regions: sea ice and land ice. Land ice contributes to SLR and sea ice does not. This article explores the characteristics of sea ice and land ice and provides some hands-on…

  2. Landscape phenology of Wisconsin's temperate mixed forest

    Science.gov (United States)

    Liang, Liang

    This dissertation covers an intensive study of the landscape phenology of Wisconsin's temperate mixed forest. It endeavors to connect conventional plant phenology study back to its ecological complexity (from gardens/trees to the forest) and to compare field-observed phenology with remotely sensed phenology for regional to global monitoring/forecasting applications (from the forest to biomes). A new research perspective: landscape phenology (LP) is proposed in this dissertation. LP is defined as an approach to seasonal vegetation dynamics that integrates spatial patterns and temporal processes within heterogeneous environment across multiple scales. High density in situ observations, remote sensing data, and spatio-temporal analysis are employed for understanding patterns and processes within the complexity of seasonal landscape dynamics. In particular, bi-daily spring forest phenologies of multiple tree/shrub species and understory plants were observed using field protocols or digital photography; high-frequency micrometeorological measurements were used in tandem with LiDAR-based microtopography/canopy heights as well as soil condition data, to characterize microenvironments; and high-resolution, multi-temporal satellite images were employed to facilitate plant community delineation and landscape scaling. A hierarchical upscaling approach is introduced, aiming to integrate in situ phenological observations with the remotely sensed phenological measures. Primary results from this work include: a detailed account of spatio-temporal variations of spring plant phenology and their environmental drivers within a typical seasonal forest; thermal time (accumulated growing degree hours) driven linear phenological models for six forest species; a landscape-level phenological progression regime driven by antecedent weather fluctuations; a conceptual landscape phenology model that assigns phenological behaviors to levels of population, community, and ecosystem patch; and a

  3. [The polarization characteristics distribution and correction method of the polarization coupling error in ocean remote sensing system].

    Science.gov (United States)

    Gao, Jun; Wang, Shu-Peng; Gu, Xing-Fa; Yu, Tao; Fang, Li

    2012-06-01

    With the development of the quantitative researches using ocean color remote sensing data sets, study on reducing the uncertainty of the response of the ocean color remote sensors to the polarization characteristics of the target has been attracting more and more attention recently. Taking MODIS as an example, the polarization distribution in the whole field of view was analyzed. For the atmosphere path radiance and the apparent radiance considering the coupling between ocean surface and atmosphere, the polarization distribution has a strong relation with the imaging geometry. Compared to the contribution of the polarization from the rough sea surface, the contribution from the atmosphere is dominated. Based on the polarization characteristics in the field of view, the influence of the polarization coupling error on the quality of the satellite data was studied with the assumption of different polarization sensitivities. It was found that errors due to polarization sensitivity in the field of view are lower than water leaving radiance only when the polarization sensitivity is less than 2%. And in this case it can meet the need of the retrieval of water leaving radiative products. The method of the compensation for the polarization coupling error due to the atmosphere is proposed, which proved to be effective to improve the utilization of satellite data and the accuracy of measured radiance by remote sensor.

  4. Atmospheric forcing of sea ice leads in the Beaufort Sea

    Science.gov (United States)

    Lewis, B. J.; Hutchings, J.; Mahoney, A. R.; Shapiro, L. H.

    2016-12-01

    Leads in sea ice play an important role in the polar marine environment where they allow heat and moisture transfer between the oceans and atmosphere and act as travel pathways for both marine mammals and ships. Examining AVHRR thermal imagery of the Beaufort Sea, collected between 1994 and 2010, sea ice leads appear in repeating patterns and locations (Eicken et al 2005). The leads, resolved by AVHRR, are at least 250m wide (Mahoney et al 2012), thus the patterns described are for lead systems that extend up to hundreds of kilometers across the Beaufort Sea. We describe how these patterns are associated with the location of weather systems relative to the coastline. Mean sea level pressure and 10m wind fields from ECMWF ERA-Interim reanalysis are used to identify if particular lead patterns can be uniquely forecast based on the location of weather systems. Ice drift data from the NSIDC's Polar Pathfinder Daily 25km EASE-Grid Sea Ice Motion Vectors indicates the role shear along leads has on the motion of ice in the Beaufort Gyre. Lead formation is driven by 4 main factors: (i) coastal features such as promontories and islands influence the origin of leads by concentrating stresses within the ice pack; (ii) direction of the wind forcing on the ice pack determines the type of fracture, (iii) the location of the anticyclone (or cyclone) center determines the length of the fracture for certain patterns; and (iv) duration of weather conditions affects the width of the ice fracture zones. Movement of the ice pack on the leeward side of leads originating at promontories and islands increases, creating shear zones that control ice transport along the Alaska coast in winter. . Understanding how atmospheric conditions influence the large-scale motion of the ice pack is needed to design models that predict variability of the gyre and export of multi-year ice to lower latitudes.

  5. [Review] Polarization and Polarimetry

    Science.gov (United States)

    Trippe, Sascha

    2014-02-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

  6. Biogeochemical Coupling between Ocean and Sea Ice

    Science.gov (United States)

    Wang, S.; Jeffery, N.; Maltrud, M. E.; Elliott, S.; Wolfe, J.

    2016-12-01

    Biogeochemical processes in ocean and sea ice are tightly coupled at high latitudes. Ongoing changes in Arctic and Antarctic sea ice domain likely influence the coupled system, not only through physical fields but also biogeochemical properties. Investigating the system and its changes requires representation of ocean and sea ice biogeochemical cycles, as well as their coupling in Earth System Models. Our work is based on ACME-HiLAT, a new offshoot of the Community Earth System Model (CESM), including a comprehensive representation of marine ecosystems in the form of the Biogeochemical Elemental Cycling Module (BEC). A full vertical column sea ice biogeochemical module has recently been incorporated into the sea ice component. We have further introduced code modifications to couple key growth-limiting nutrients (N, Si, Fe), dissolved and particulate organic matter, and phytoplankton classes that are important in polar regions between ocean and sea ice. The coupling of ocean and sea ice biology-chemistry will enable representation of key processes such as the release of important climate active constituents or seeding algae from melting sea ice into surface waters. Sensitivity tests suggest sea ice and ocean biogeochemical coupling influences phytoplankton competition, biological production, and the CO2 flux. Sea ice algal seeding plays an important role in determining phytoplankton composition of Arctic early spring blooms, since different groups show various responses to the seeding biomass. Iron coupling leads to increased phytoplankton biomass in the Southern Ocean, which also affects carbon uptake via the biological pump. The coupling of macronutrients and organic matter may have weaker influences on the marine ecosystem. Our developments will allow climate scientists to investigate the fully coupled responses of the sea ice-ocean BGC system to physical changes in polar climate.

  7. Polarization feedback laser stabilization

    Science.gov (United States)

    Esherick, P.; Owyoung, A.

    1987-09-28

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.

  8. NSF Workshop on High­Performance Distributed Computing and Polar Sciences

    OpenAIRE

    Shantenu Jha; Lynn Yarmey

    2015-01-01

    Climate change in the 20th and 21st century is dramatically changing the polar regions. This is documented by numerous studies, for example as thawing permafrost, retreating Arctic sea ice and accelerating mass loss from glaciers and ice sheets. These changes may have widespread consequences for many aspects of the earth systems, e.g. carbon budget, food and water security, sea levels, and freshwater input to oceans. To understand the changing polar regions and their global impacts, scientist...

  9. Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum

    OpenAIRE

    Fraser, Ceridwen I.; Nikula, Raisa; Spencer, Hamish G.; Waters, Jonathan M.

    2009-01-01

    The end of the Last Glacial Maximum (LGM) dramatically reshaped temperate ecosystems, with many species moving poleward as temperatures rose and ice receded. Whereas reinvading terrestrial taxa tracked melting glaciers, marine biota recolonized ocean habitats freed by retreating sea ice. The extent of sea ice in the Southern Hemisphere during the LGM has, however, yet to be fully resolved, with most palaeogeographic studies suggesting only minimal or patchy ice cover in subantarctic waters. H...

  10. Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea

    Science.gov (United States)

    Granfors, Anna; Ahnoff, Martin; Mills, Matthew M.; Abrahamsson, Katarina

    2014-12-01

    Recent studies have recognized sea ice as a source of reactive iodine to the Antarctic boundary layer. Volatile iodinated compounds (iodocarbons) are released from sea ice, and they have been suggested to contribute to the formation of iodine oxide (IO), which takes part in tropospheric ozone destruction in the polar spring. We measured iodocarbons (CH3I, CH2ClI, CH2BrI, and CH2I2) in sea ice, snow, brine, and air during two expeditions to Antarctica, OSO 10/11 to the Amundsen Sea during austral summer and ANT XXIX/6 to the Weddell Sea in austral winter. These are the first reported measurements of iodocarbons from the Antarctic winter. Iodocarbons were enriched in sea ice in relation to seawater in both summer and winter. During summer, the positive relationship to chlorophyll a biomass indicated a biological origin. We suggest that CH3I is formed biotically in sea ice during both summer and winter. For CH2ClI, CH2BrI, and CH2I2, an additional abiotic source at the snow/ice interface in winter is suggested. Elevated air concentrations of CH3I and CH2ClI during winter indicate that they are enriched in lower troposphere and may take part in the formation of IO at polar sunrise.

  11. Late-Holocene dynamics of sea-surface temperature and terrestrial hydrology in southwestern Africa

    NARCIS (Netherlands)

    Granger, R.; Meadows, M.E.; Hahn, A.; Zabel, M.; Stuut, J-B W.; Herrmann, N.; Schefuß, E.

    2018-01-01

    Southwest Africa is an important region for paleo-climatic studies, being influenced by both tropical and temperate climate systems and thus reflecting the interplay of variable controls. The aim of this study was to unravel the interaction of sea-surface temperature (SST) changes in the

  12. Seasonal variation in the antifouling defence of the temperate brown alga Fucus vesiculosus.

    Science.gov (United States)

    Saha, Mahasweta; Wahl, Martin

    2013-01-01

    The important role of marine epibiotic biofilms in the interactions of the host with its environment has been acknowledged recently. Previous studies with the temperate brown macroalga Fucus vesiculosus have identified polar and non-polar compounds recovered from the algal surface that have the potential to control such biofilms. Furthermore, both the fouling pressure and the composition of the epibiotic bacterial communities on this macroalga varied seasonally. The extent to which this reflects a seasonal fluctuation of the fouling control mechanisms of the host is, however, unexplored in an ecological context. The present study investigated seasonal variation in the anti-settlement activity of surface extracts of F. vesiculosus against eight biofilm-forming bacteria isolated from rockweed-dominated habitats, including replication of two populations from two geographically distant sites. The anti-settlement activity at both sites was found to vary temporally, reaching a peak in summer/autumn. Anti-settlement activity also showed a consistent and strong difference between sites throughout the year. This study is the first to report temporal variation of antifouling defence originating from ecologically relevant surface-associated compounds.

  13. Estimating Canopy Height of a Temperate Forest from TanDEM-X and LVIS Data

    Science.gov (United States)

    Qi, W.; Dubayah, R.; Kugler, F.

    2014-12-01

    The recently launched TanDEM-X mission is the first single-pass polarimetric interferometer in space allowing global estimation of forest parameters without any temporal decorrelation. This study investigates the potential of single-polarized TanDEM-X data for forest height inversion and structure characterization. For this purpose, a temperate forest - Hubbard Brook Experimental Forest (HBEF) in New Hampshire is chosen for experiment. Stripmap-mode HH-polarized TanDEM-X bistatic data (with resolution at 3 m) acquired at different baselines was used. LVIS data was applied to remove the ground phase component of the TanDEM-X interferogram and to validate the derived results. Forest parameters, e.g. canopy height and extinction coefficient were estimated based on Random Volume over Ground (RVoG) model. Scattering phase height (SPH) was also calculated and validated against LVIS rh100. A clear correlation was observed between TanDEM-X SPH and the reference height with an r2 of around 0.6 at 150m resolution. The inverted tree height had an RMSE of less than 3.4 m and an r2 of around 0.7 at the same resolution. It is shown that TanDEM-X data has great potential for improving the understanding and quantification of global forest canopy height and structure.

  14. Identifying marine Important Bird Areas using at-sea survey data

    Science.gov (United States)

    Smith, Melanie A.; Walker, Nathan J.; Free, Christopher M.; Kirchhoff, Matthew J.; Drew, Gary S.; Warnock, Nils; Stenhouse, Iain J.

    2014-01-01

    Effective marine bird conservation requires identification of at-sea locations used by populations for foraging, staging, and migration. Using an extensive database of at-sea survey data spanning over 30 years, we developed a standardized and data-driven spatial method for identifying globally significant marine Important Bird Areas in Alaska. To delineate these areas we developed a six-step process: binning data and accounting for unequal survey effort, filtering input data for persistence of species use, using a moving window analysis to produce maps representing a gradient from low to high abundance, drawing core area boundaries around major concentrations based on abundance thresholds, validating the results, and combining overlapping boundaries into important areas for multiple species. We identified 126 bird core areas which were merged into 59 pelagic sites important to 45 out of 57 species assessed. The final areas included approximately 34–38% of all marine birds in Alaska waters, within just 6% of the total area. We identified globally significant Important Bird Areas spanning 20 degrees of latitude and 56 degrees of longitude, in two different oceans, with climates ranging from temperate to polar. Although our maps did suffer from some data gaps, these gaps did not preclude us from identifying sites that incorporated 13% of the assessed continental waterbird population and 9% of the assessed global seabird population. The application of this technique over a large and productive region worked well for a wide range of birds, exhibiting a variety of foraging strategies and occupying a variety of ecosystem types.

  15. Pleistocene reduction of polar ice caps: Evidence from Cariaco Basin marine sediments

    Science.gov (United States)

    Poore, R.Z.; Dowsett, H.J.

    2001-01-01

    Sea level is projected to rise between 13 and 94 cm over the next 100 yr due to continued climate warming. The sea-level projections assume that polar ice sheets will remain stable or even increase on time scales of centuries, but controversial geologic evidence suggests that current polar ice sheets have been eliminated or greatly reduced during previous Pleistocene interglacials indicating that modern polar ice sheets have become unstable within the natural range of interglacial climates. Sea level may have been more than 20 m higher than today during a presumably very warm interglacial about 400 ka during marine isotope stage 11. Because of the implications for future sea level rise, additional study of the conflicting evidence for warmer conditions and higher sea level during marine isotope stage 11 is needed. Here we present microfossil and isotopic data from marine sediments of the Cariaco Basin supporting the interpretation that global sea level was 10-20 m higher than today during marine isotope stage 11. The increased sea level requires reduction in modern polar ice sheets and is consistent with the interpretation that the West Antarctic ice sheet and the Greenland ice sheet were absent or greatly reduced during marine isotope stage 11. Our results show a warm marine isotope stage 11 interglacial climate with sea level as high as or above modern sea level that lasted for 25 to 30 k.y. Variations in Earth's orbit around the sun (Milankovitch cycles) are considered to be a primary external force driving glacial-interglacial cycles. Current and marine isotope stage 11 Milankovitch forcing are very similar, suggesting that the present interglacial (Holocene) that began ca. 10 ka will continue for another 15 to 20 k.y. Therefore any anthropogenic climate warming will accelerate the natural process toward reduction in polar ice sheets. The potential for increased rates of sea level rise related to polar ice sheet decay should be considered as a potential natural

  16. Hail resistance of solar collectors with tempered glass covers

    Science.gov (United States)

    Lof, G. O. G.; French, R. R.

    1980-01-01

    The resistance of solar collectors glazed with 3 mm of tempered glass to hailstones of up to 10 cm in diameter and 0.5 kg in weight which fell on Fort Collins, Colorado is discussed. Of the ten solar heating systems directly in the hailpath with tempered glass covers, seven were undamaged, two lost one collector panel each, and a 700-panel collector had seven broken covers, amounting to a total breakage of nine panels out of 956, approximately 1%. In addition, one system with nontempered glass covers suffered two glass punctures in a 26-panel collector. It is concluded that the risk of hail damage to commercial solar collectors glazed with 3-mm tempered glass is negligibly small, and greatly exceeded by the risk of hail damage to the roofs of buildings and automobiles or to fiberglass-reinforced polyester sheets used as collector glazings.

  17. Tempered stable distributions stochastic models for multiscale processes

    CERN Document Server

    Grabchak, Michael

    2015-01-01

    This brief is concerned with tempered stable distributions and their associated Levy processes. It is a good text for researchers interested in learning about tempered stable distributions.  A tempered stable distribution is one which takes a stable distribution and modifies its tails to make them lighter. The motivation for this class comes from the fact that infinite variance stable distributions appear to provide a good fit to data in a variety of situations, but the extremely heavy tails of these models are not realistic for most real world applications. The idea of using distributions that modify the tails of stable models to make them lighter seems to have originated in the influential paper of Mantegna and Stanley (1994). Since then, these distributions have been extended and generalized in a variety of ways. They have been applied to a wide variety of areas including mathematical finance, biostatistics,computer science, and physics.

  18. SMOS sea ice product: Operational application and validation in the Barents Sea marginal ice zone

    DEFF Research Database (Denmark)

    Kaleschke, Lars; Tian-Kunze, Xiangshan; Maaß, Nina

    2016-01-01

    Brightness temperatures at 1.4. GHz (L-band) measured by the Soil Moisture and Ocean Salinity (SMOS) Mission have been used to derive the thickness of sea ice. The retrieval method is applicable only for relatively thin ice and not during the melting period. Hitherto, the availability of ground...... truth sea ice thickness measurements for validation of SMOS sea ice products was mainly limited to relatively thick ice. The situation has improved with an extensive field campaign in the Barents Sea during an anomalous ice edge retreat and subsequent freeze-up event in March 2014. A sea ice forecast...... system for ship route optimisation has been developed and was tested during this field campaign with the ice-strengthened research vessel RV Lance. The ship cruise was complemented with coordinated measurements from a helicopter and the research aircraft Polar 5. Sea ice thickness was measured using...

  19. Phylogenetic Relationships among Deep-Sea and Chemosynthetic Sea Anemones: Actinoscyphiidae and Actinostolidae (Actiniaria: Mesomyaria)

    Science.gov (United States)

    Rodríguez, Estefanía; Daly, Marymegan

    2010-01-01

    Sea anemones (Cnidaria, Actiniaria) are present in all marine ecosystems, including chemosynthetic environments. The high level of endemicity of sea anemones in chemosynthetic environments and the taxonomic confusion in many of the groups to which these animals belong makes their systematic relationships obscure. We use five molecular markers to explore the phylogenetic relationships of the superfamily Mesomyaria, which includes most of the species that live in chemosynthetic, deep-sea, and polar sea habitats and to test the monophyly of the recently defined clades Actinostolina and Chemosynthina. We found that sea anemones of chemosynthetic environments derive from at least two different lineages: one lineage including acontiate deep-sea taxa and the other primarily encompassing shallow-water taxa. PMID:20532040

  20. Phylogenetic relationships among deep-sea and chemosynthetic sea anemones: actinoscyphiidae and actinostolidae (Actiniaria: Mesomyaria.

    Directory of Open Access Journals (Sweden)

    Estefanía Rodríguez

    Full Text Available Sea anemones (Cnidaria, Actiniaria are present in all marine ecosystems, including chemosynthetic environments. The high level of endemicity of sea anemones in chemosynthetic environments and the taxonomic confusion in many of the groups to which these animals belong makes their systematic relationships obscure. We use five molecular markers to explore the phylogenetic relationships of the superfamily Mesomyaria, which includes most of the species that live in chemosynthetic, deep-sea, and polar sea habitats and to test the monophyly of the recently defined clades Actinostolina and Chemosynthina. We found that sea anemones of chemosynthetic environments derive from at least two different lineages: one lineage including acontiate deep-sea taxa and the other primarily encompassing shallow-water taxa.

  1. Property Analysis and Suppression Method of Real Measured Sea Spikes

    Directory of Open Access Journals (Sweden)

    Huang Yong

    2015-06-01

    Full Text Available In case of high-resolution, low grazing angle, high sea state, and horizontal transmitting, horizontal receiving polarization, the radar returns are strengthened, resulting in sea spikes. The sea spikes have the characteristics of high amplitudes, nonstationary, and non-Gaussian, which have a strong impact on the radar detection of weak marine moving targets. This study proposes a method for sea clutter suppression. Firstly, based on the sea spikes identification and selection method, the amplitude, temporal correlation, Doppler spectrum, and fractional power spectrum properties of sea spikes are analyzed. Secondly, the data to be detected are chosen by selecting the background clutter with minimum mean power, which can also eliminate the sea spikes. Correspondingly, sea clutter is suppressed with improved Signal-to-Clutter Ratio (SCR. Finally, the results of experiment with real radar data verify the effectiveness of the proposed method.

  2. Newly Formed Sea Ice in Arctic Leads Monitored by C- and L-Band SAR

    Science.gov (United States)

    Johansson, A. Malin; Brekke, Camilla; Spreen, Gunnar; King, Jennifer A.; Gerland, Sebastian

    2016-08-01

    We investigate the scattering entropy and co-polarization ratio for Arctic lead ice using C- and L-band synthetic aperture radar (SAR) satellite scenes. During the Norwegian Young sea ICE (N-ICE2015) cruise campaign overlapping SAR scenes, helicopter borne sea ice thickness measurements and photographs were collected. We can therefore relate the SAR signal to sea ice thickness measurements as well as photographs taken of the sea ice. We show that a combination of scattering and co-polarization ratio values can be used to distinguish young ice from open water and surrounding sea ice.

  3. Polar bears: the fate of an icon.

    Science.gov (United States)

    Fitzgerald, Kevin T

    2013-11-01

    Polar bears are one of the most iconic animals on our planet. Worldwide, even people who would never see one are drawn to these charismatic arctic ice hunters. They are the world's largest terrestrial carnivore, and despite being born on land, they spend most of their lives out on the sea ice and are considered a marine mammal. Current global studies estimate there are around 20,000 animals in some 19 discrete circumpolar populations. Aside from pregnant females denning in the winter months to give birth, the white bears do not hibernate. They spend their winters on the sea ice hunting seals, an activity they are spectacularly adapted for. Research on these animals is incredibly difficult because of the inhospitable surroundings they inhabit and how inaccessible they make the bears. For many years, the sum of our understanding of the natural history of polar bears came from tracks, scats, the remains of their kills, abandoned dens, and anecdotal observations of native hunters, explorers, and early biologists. Nonetheless, the last 40 years have seen a much better picture of their biology emerge thanks to, first, dedicated Canadian researchers and, later, truly international efforts of workers from many countries. Veterinarians have contributed to our knowledge of the bears by delivering and monitoring anesthesia, obtaining blood samples, performing necropsies, investigating their reproduction, conducting radiotelemetry studies, and examining their behavior. Recently, new technologies have been developed that revolutionize the study of the lives and natural history of undisturbed polar bears. These advances include better satellite radiotelemetry equipment and the development of remote-controlled miniature devices equipped with high-definition cameras. Such new modalities provide dramatic new insights into the life of polar bears. The remarkable degree of specialized adaptation to life on the sea ice that allowed the bears to be successful is the very reason that

  4. Diversity and abundance of photosynthetic sponges in temperate Western Australia

    Directory of Open Access Journals (Sweden)

    Brümmer Franz

    2009-02-01

    Full Text Available Abstract Background Photosynthetic sponges are important components of reef ecosystems around the world, but are poorly understood. It is often assumed that temperate regions have low diversity and abundance of photosynthetic sponges, but to date no studies have investigated this question. The aim of this study was to compare the percentages of photosynthetic sponges in temperate Western Australia (WA with previously published data on tropical regions, and to determine the abundance and diversity of these associations in a range of temperate environments. Results We sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges. Conclusion Photosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide

  5. Polarization modulators for CMBPol

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P A R; Savini, G [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Chuss, D T [NASA Goddard Space Flight Center, Code 665, Greenbelt, MD, 20771 (United States); Hanany, S [School of Physics and Astronomy, University of Minnesota/Twin Cities, Minneapolis, MN, 55455 (United States); Haynes, V; Pisano, G [University of Manchester, School of Physics and Astronomy - Alan Turing Building, Upper Brooke street, Manchester, M13 4PL (United Kingdom); Keating, B G [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0424 (United States); Kogut, A [Code 665 Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruhl, J E [Physics Department, Case Western Reserve University, Cleveland, OH, 44106 (United States); Wollack, E J [Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2009-03-01

    We review a number of technologies that are candidates for active polarization modulators for CMBPol. The technologies are appropriate for instruments that use bolometric detectors and include birefringent crystal-based and metal-mesh-based half-wave plates, variable phase polarization modulator, Faraday rotator, and photolithographed modulators. We also give a current account of the status of millimeter-wave orthomode transducers.

  6. The Polar Insulation Investigation

    Science.gov (United States)

    Urban-Rich, Juanita

    2006-01-01

    In this article, the author developed an activity called "The Polar Insulation Investigation." This activity builds on students' natural interest in "things polar" and introduces them to animal adaptations in a unique way. The aim of the exploration is to determine the role of animal coverings (e.g., blubber, fur, and feathers) and to see which is…

  7. Galactic Diffuse Polarized Emission

    Indian Academy of Sciences (India)

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission ...

  8. Terahertz polarization imaging

    NARCIS (Netherlands)

    Van der Valk, N.C.J.; Van der Marel, W.A.M.; Planken, P.C.M.

    2005-01-01

    We present a new method to measure the polarization state of a terahertz pulse by using a modified electrooptic sampling setup. To illustrate the power of this method, we show two examples in which the knowledge of the polarization of the terahertz pulse is essential for interpreting the results:

  9. Effects of wave exposure on circulation in a temperate reef environment

    Science.gov (United States)

    Symonds, Graham; Zhong, Liejun; Mortimer, Nick A.

    2011-09-01

    Observations of waves and currents in a temperate reef environment off southwestern Western Australia over a period of 1 year reveal the relative importance of wind and wave forcing. During periods of low waves, linear regression analysis shows alongshore currents seaward and shoreward of the reef line are reasonably well predicted using 1% and 0.5% of the wind speed, respectively. However, shoreward of the reef line anomalously strong currents were often observed during periods of light or even opposing winds and the mean sea surface was elevated relative to offshore of the reefs. These anomalous currents and elevated sea level occur during periods of high waves and both are correlated with the root-mean-square wave height seaward of the reefs, similar to what has been observed in coral reef environments. The observations were simulated with the numerical model XBeach which includes radiation stress forcing due to the presence of the waves. The model was also used to examine the dynamics of the wave-driven flow in terms of the momentum balance. As on a coral reef, through the surf zone over the reef bottom, friction is balanced by the sum of the radiation stress gradient and pressure gradient. Away from the reefs the radiation stress gradients are small and the momentum balance is between bottom friction and pressure gradient.

  10. Marine biodegradation of crude oil in temperate and Arctic water samples.

    Science.gov (United States)

    Kristensen, Mette; Johnsen, Anders R; Christensen, Jan H

    2015-12-30

    Despite increased interest in marine oil exploration in the Arctic, little is known about the fate of Arctic offshore oil pollution. Therefore, in the present study, we examine the oil degradation potential for an Arctic site (Disko Bay, Greenland) and discuss this in relation to a temperate site (North Sea, Denmark). Biodegradation was assessed following exposure to Oseberg Blend crude oil (100 mg L(-1)) in microcosms. Changes in oil hydrocarbon fingerprints of polycyclic aromatic hydrocarbons (PAHs), alkyl-substituted PAHs, dibenzothiophenes, n-alkanes and alkyltoluenes were measured by gas chromatography-mass spectrometry (GC-MS). In the Disko Bay sample, the degradation order was n-alkanes>alkyltoluenes (para->meta->ortho-isomers)>PAHs and dibenzothiophenes, whereas, the degradation order in the North Sea samples was PAHs and dibenzothiophenes>alkyltoluenes>n-alkanes. These differences in degradation patterns significantly affect the environmental risk of oil spills and emphasise the need to consider the specific environmental conditions when conducting risk assessments of Arctic oil pollution. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Influence of tempering temperature on mechanical properties of cast steels

    OpenAIRE

    G. Golański

    2008-01-01

    The paper presents results of research on the influence of tempering temperature on structure and mechanical properties of bainite hardened cast steel: G21CrMoV4 – 6 (L21HMF) and G17CrMoV5 – 10 (L17HMF). Investigated cast steels were taken out from internal frames of steam turbines serviced for long time at elevated temperatures. Tempering of the investigated cast steel was carried out within the temperature range of 690 ÷ 730 C (G21CrMoV4 – 6) and 700 ÷ 740 C (G17CrMoV5 – 10). After temperin...

  12. Polarization Mode Dispersion

    CERN Document Server

    Galtarossa, Andrea

    2005-01-01

    This book contains a series of tutorial essays on polarization mode dispersion (PMD) by the leading experts in the field. It starts with an introductory review of the basic concepts and continues with more advanced topics, including a thorough review of PMD mitigation techniques. Topics covered include mathematical representation of PMD, how to properly model PMD in numerical simulations, how to accurately measure PMD and other related polarization effects, and how to infer fiber properties from polarization measurements. It includes discussions of other polarization effects such as polarization-dependent loss and the interaction of PMD with fiber nonlinearity. It additionally covers systems issues like the impact of PMD on wavelength division multiplexed systems. This book is intended for research scientists or engineers who wish to become familiar with PMD and its system impacts.

  13. Parallel Polarization State Generation

    CERN Document Server

    She, Alan

    2016-01-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristi...

  14. Polarization Optics in Telecommunications

    CERN Document Server

    Damask, Jay N

    2005-01-01

    The strong investments into optical telecommunications in the late 1990s resulted in a wealth of new research, techniques, component designs, and understanding of polarization effects in fiber. Polarization Optics in Telecommunications brings together recent advances in the field to create a standard, practical reference for component designers and optical fiber communication engineers. Beginning with a sound foundation in electromagnetism, the author offers a dissertation of the spin-vector formalism of polarization and the interaction of light with media. Applications discussed include optical isolators, optical circulators, fiber collimators, and a variety of applied waveplate and prism combinations. Also included in an extended discussion of polarization-mode dispersion (PMD) and polarization-dependent loss (PDL), their representation, behavior, statistical properties, and measurement. This book draws extensively from the technical and patent literature and is an up-to-date reference for researchers and c...

  15. Optically polarized 3He

    Science.gov (United States)

    Gentile, T. R.; Nacher, P. J.; Saam, B.; Walker, T. G.

    2017-10-01

    This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

  16. A tale of two polar bear populations: Ice habitat, harvest, and body condition

    Science.gov (United States)

    Rode, K.D.; Peacock, E.; Taylor, M.; Stirling, I.; Born, E.W.; Laidre, K.L.; Wiig, O.

    2012-01-01

    One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977-1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition. ?? 2011 The Society of Population Ecology and Springer.

  17. PREVALENCE OF ANTIBODIES AGAINST TOXOPLASMA GONDII IN POLAR BEARS (URSUS MARITIMUS) FROM SVALBARD AND EAST GREENLAND

    Science.gov (United States)

    Serum samples from 419 polar bears (Ursus maritimus) from Svalbard and the Barents Sea (collected 1990 - 2000) and 108 polar bears from East Greenland (collected 1999 - 2004) were assayed for antibodies against Toxoplasma gondii using the modified agglutination test (MAT). Antibody prevalences were ...

  18. Molecular content of polar-ring galaxies

    Science.gov (United States)

    Combes, F.; Moiseev, A.; Reshetnikov, V.

    2013-06-01

    We have searched for CO lines in a sample of 21 new morphologically determined polar-ring galaxies (of which nine are kinematically confirmed), obtained from a wide search in the Galaxy Zoo project by Moiseev and collaborators. Polar-ring galaxies (PRGs) are a unique class of objects, tracing special episodes in the galaxy mass assembly: they can be formed through galaxy interaction and merging, but also through accretion from cosmic filaments. Furthermore, they enable the study of dark matter haloes in three dimensions. The polar ring itself is a sub-system rich in gas, where molecular gas is expected, and new stars are formed. Among the sample of 21 PRGs, we have detected five CO-rich systems, that can now be followed up with higher spatial resolution. Their average molecular mass is 9.4 × 109M⊙, and their average gas fraction is 27% of their baryonic mass, with a range from 15 to 43%, implying that they have just accreted a large amount of gas. The position of the detected objects in the velocity-magnitude diagram is offset from the Tully-Fisher relation of normal spirals, as was already found for PRGs. This work is part of our multi-wavelength project to determine the detailed morphology and dynamics of PRGs, test through numerical models their formation scenario, and deduce their dark matter content and 3D-shape. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Spectra of detections are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5">130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/554/A11

  19. Dsp in Moroccan Mediterranean Sea.

    Science.gov (United States)

    Rachid, Fadel

    At sea temperate, there is usually a sole major floraison of the phytoplancton (in the spring) that exhausts the available stock of nutritious salt. This phenomenon is natural. It's more known under the name of "red tide or colored waters", it brings about a danger, with hazardous consequences on the wildlife water wildlife. The toxins emitted by certain seaweeds, of this phytoplancton, are transmitted through the trophic chain to man. Sometimes the contamination of these sea fruits provokes empoisoning to the consumers. Sometimes phytoplanctonics efflorescences do not present any significant coloring but can generate an increased liberation of toxins in sea water. The relative concentration of the one here then is detected in the shellfishes. These organisms concentrate the phocotoxines in their hepatopancreas. These are therefore bio potential indicators of the sea environment. We studied, in parallel, the variation of the characteristic abiotics of the Mediterranean sites previously choosen (physico-chimicals parameters and oceanographics parameters) and the variation of the relative toxicity of the bio indicators in every site. It in springs that the zones navies, subjected to important water provisions coming from a river, undergo several excessive floraisons during the spring and the summer, thanks to their continuous supplying in nutriments. We noted that the arrival new water masses. We draw from this that the coastal areas, due to the precipitations of the winter, translates itself at the level of the embouchure of the estuary Oued Laou by the maximum concentration of contained toxins in the shellfishes and that these waters were loaded with drifts of the olive waste, liquid loss abandoned to himself after extraction of the oil of the renowned olives of this region.

  20. SWFSC/MMTD/CCE: Leatherback Use of Temperate Habitat (LUTH) 2008

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Leatherback Use of Temperate Habitat (LUTH) survey is an ecosystem assessment of temperate foraging habitats of endangered leatherback turtles off the coast of...

  1. Sea ice contribution to the air-sea CO{sub 2} exchange in the Arctic and Southern Oceans

    Energy Technology Data Exchange (ETDEWEB)

    Rysgaard, Soeren (Greenland Climate Research Centre, Greenland Inst. of Natural Resources, Nuuk, Greenland (Denmark); Centre for Earth Observation Science, CHR Faculty of Environment Earth and Resources, Univ. of Manitoba, Winnipeg (Canada)), e-mail: rysgaard@natur.gl; Bendtsen, Joergen (Greenland Climate Research Centre, Greenland Inst. of Natural Resources, Nuuk, Greenland (Denmark); Centre for Ice and Climate, Niels Bohr Inst., Univ. of Copenhagen, Copenhagen O (Denmark)); Delille, Bruno (Unit' e d' Oceanographie Chimique, Interfacultary Centre for Marine Research, Universite de Liege, Liege (Belgium)); Dieckmann, Gerhard S. (Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany)); Glud, Ronnie N. (Greenland Climate Research Centre, Greenland Inst. of Natural Resources, Nuuk, Greenland (Denmark); Scottish Association of Marine Sciences, Scotland UK, Southern Danish Univ. and NordCee, Odense M (Denmark)); Kennedy, Hilary; Papadimitriou, Stathys (School of Ocean Sciences, Bangor Univ., Menai Bridge, Anglesey, Wales (United Kingdom)); Mortensen, John (Greenland Climate Research Centre, Greenland Inst. of Natural Resources, Nuuk, Greenland (Denmark)); Thomas, David N. (School of Ocean Sciences, Bangor Univ., Menai Bridge, Anglesey, Wales (United Kingdom); Finnish Environment Inst. (SYKE), Marine Research Centre, Helsinki (Finland)); Tison, Jean-Louis (Glaciology Unit, Dept. of Earth and Environmental Sciences, Universite Libre de Bruxelles, Bruxelles, (Belgium))

    2011-11-15

    Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO{sub 2} and the subsequent effect on air-sea CO{sub 2} exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air-sea CO{sub 2} exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO{sub 2} uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO{sub 2} uptake in ice-free polar seas. This sea-ice driven CO{sub 2} uptake has not been considered so far in estimates of global oceanic CO{sub 2} uptake. Net CO{sub 2} uptake in sea-ice-covered oceans can be driven by; (1) rejection during sea-ice formation and sinking of CO{sub 2}-rich brine into intermediate and abyssal oceanic water masses, (2) blocking of air-sea CO{sub 2} exchange during winter, and (3) release of CO{sub 2}-depleted melt water with excess total alkalinity during sea-ice decay and (4) biological CO{sub 2} drawdown during primary production in sea ice and surface oceanic waters

  2. The investigation of applicability of the Hollomon-Jaffe equation on tempering the HSLA steel

    OpenAIRE

    A. Patarić; Mihailović, M.; Z. Gulišija; Z. Janjušević

    2009-01-01

    High strength low-alloyed (HSLA) Cr-Mn-Si steels belong to a group of steels that can reach their full mechanical properties after quenching and tempering. Those properties depend both on the temperature and time of tempering. Knowing the tempering parameters, it is possible to reach the desired properties of the treated steel. Some results on investigating the Hollomon-Jaffe equation (in parametric form) application for tempering of HSLA steel, are shown in this paper. The experiments were p...

  3. Sea Ice Concentration and Extent

    Science.gov (United States)

    Comiso, Josefino C.

    2014-01-01

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

  4. Radiative transfer in atmosphere-sea ice-ocean system

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Z.; Stamnes, K.; Weeks, W.F. [Univ. of Alaska, Fairbanks, AK (United States); Tsay, S.C. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    1996-04-01

    Radiative energy is critical in controlling the heat and mass balance of sea ice, which significantly affects the polar climate. In the polar oceans, light transmission through the atmosphere and sea ice is essential to the growth of plankton and algae and, consequently, to the microbial community both in the ice and in the ocean. Therefore, the study of radiative transfer in the polar atmosphere, sea ice, and ocean system is of particular importance. Lacking a properly coupled radiative transfer model for the atmosphere-sea ice-ocean system, a consistent study of the radiative transfer in the polar atmosphere, snow, sea ice, and ocean system has not been undertaken before. The radiative transfer processes in the atmosphere and in the ice and ocean have been treated separately. Because the radiation processes in the atmosphere, sea ice, and ocean depend on each other, this separate treatment is inconsistent. To study the radiative interaction between the atmosphere, clouds, snow, sea ice, and ocean, a radiative transfer model with consistent treatment of radiation in the coupled system is needed and is under development.

  5. The Probing Radio Signal Polarization Effect on Separation Efficiency of Surface Target Response

    Directory of Open Access Journals (Sweden)

    A. N. Pinchuk

    2015-01-01

    Full Text Available The aim of the study was a quantitative analysis of the level of interference with radar monitoring characteristics of surface targets, caused by the scattered electromagnetic field, arising due to the interaction between radio waves and sea surface, which is a study aspect a radiooceanography encompasses. Backscatter signal, arising from the interaction of radio waves and sea surface, extends in a direction opposite the probing radar signal of spread marine and coastal radar stations.With radar sounding of sea surface at high incidence angles of radio waves, a basic physical mechanism to form the received signal is resonant (Bragg scattering, and at small incidence angles of radio waves it is quasi-specular reflection. Consequently, the energy of electromagnetic radiation, backscattered by the sea surface, depends on the type of wave polarization: for horizontal polarization it is less than for vertical one.The paper presents a mathematical model, which describes dependence of interference level caused by interaction between radio waves and sea surface, on the radio wave polarization for the case when the same polarization is used to sent-out and receive a radio wave.To determine the noise reduction to be achievable with radar monitoring the surface targets by selecting the polarization of the probing radar signal, a signal/noise ratio is analyzed for its different polarizations.It is shown that in order to reduce the noise level caused by the interaction between radio waves and sea surface, it is possible to use the differences in the level of scattered radio signals of different polarization: with horizontally-polarized radar operation at incidence angles of 75°- 85° a signal/noise ratio is by 20-35 dB higher than that of vertically- polarized one.

  6. Pronounced anomalies of air, water, ice conditions in the Barents and Kara Seas, and the Sea of Azov

    Directory of Open Access Journals (Sweden)

    Gennady G. Matishov

    2014-06-01

    Full Text Available This paper analyses the anomalous hydrometeorological situation that occurred at the beginning of 2012 in the seas of the Russian Arctic and Russian South. Atmospheric blocking in the temperate zone and the extension of the Siberian High to the Iberian Peninsula (known as the Voeikov et al. axis led to a positive anomaly of air and water temperatures and a decrease in the ice extent in the Barents and Kara Seas. At the same time a prolonged negative air temperature anomaly was recorded in central and southern Europe and led to anomalously severe ice conditions in the Sea of Azov. Winter hydrographic conditions in the Barents and Kara Seas are illustrated by a unique set of observations made using expendable bathythermosalinographs (XCTD.

  7. 40 CFR 426.60 - Applicability; description of the automotive glass tempering subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the automotive glass tempering subcategory. 426.60 Section 426.60 Protection of Environment ENVIRONMENTAL... Automotive Glass Tempering Subcategory § 426.60 Applicability; description of the automotive glass tempering...

  8. A note on the water budget of temperate glaciers

    NARCIS (Netherlands)

    Oerlemans, J.

    2013-01-01

    In this note, the total dissipative melting in temperate glaciers is studied. The analysis is based on the notion that the dissipation is determined by the loss of potential energy due to the downward motion of mass (ice, snow, meltwater and rain). A mathematical formulation of the dissipation is

  9. Effect of climate change on temperate forest ecosystems

    NARCIS (Netherlands)

    Brolsma, R.J.|info:eu-repo/dai/nl/304847364

    2010-01-01

    In temperate climates groundwater can have a strong effect on vegetation, because it can influence the spatio-temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. Current IPCC climate projections based on CO2 emission scenarios show a global temperature rise

  10. Dry kiln schedules for commercial woods : temperate and tropical

    Science.gov (United States)

    R. Sidney Boone; Charles J. Kozlik; Paul J. Bois; Eugene M. Wengert

    1988-01-01

    This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. Kiln schedules are completely assembled and written out for easy use. Schedules for several thicknesses and specialty products (e.g. squares, handle stock, gunstock blanks) are given for many species. The majority of the schedules are from the world literature...

  11. ballistic performance of a quenched and tempered steel against ...

    African Journals Online (AJOL)

    eobe

    Author, Tel: +234-805-671-5551. BALLISTIC PERFORMANCE OF A QUENCHED AND TEMPERED STEEL. AGAINST 7.62MM CALIBRE. AGAINST 7.62MM CALIBRE PROJECTILE. PROJECTILE. PROJECTILE. O. M. Sanusi1 and J. O. Akindapo2. 1RESEARCH AND DEVELOPMENT CENTRE, DEFENCE INDUSTRIES ...

  12. The Fracture Process of Tempered Soda-Lime-Silica Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2009-01-01

    This work presents experimental observations of the characteristic fracture process of tempered glass. Square specimens with a side length of 300 mm, various thicknesses and a residual stress state characterized by photoelastic measurements were used. Fracture was initiated using a 2.5 mm diamond...

  13. Mixed livestock grazing in diverse temperate and semi-arid ...

    African Journals Online (AJOL)

    Concerns for product quality, uniformity and continuity and for animal welfare will increasingly drive production processes. In this paper, the potential of mixed grazing for higher output of quality animal products, within these constraints, is assessed under both temperate and semi-arid conditions. Complementary ...

  14. Conservation importance of early post-disturbance temperate forests

    Science.gov (United States)

    Charles Kwit; David I. King; Beverly Collins; Mark E. Swanson

    2014-01-01

    The early post-disturbance stage of temperate forest succession (also referred to as 'early-seral' or 'early-successional' forest) has been the subject of interest and debate. Often thought of as an ephemeral (and often disorganized) state of eventual closed-canopy systems, its direct and immediate role in conservation traditionally has been ignored...

  15. Effects of temperate agriculture on neotropical migrant landbirds

    Science.gov (United States)

    Nicholas L. Rodenhouse; Louis B. Best; Raymond J. O' Connor; Eric K. Bollinger

    1993-01-01

    The ecology of Neotropical migrant landbirds in temperate farmland is reviewed to develop management recommendations for the conservation of migrants. Migrants constitute about 71% of bird species using farmland and 86% of bird species nesting there. The number and abundances of Neotropical migrants using farmland are greatest in uncultivated edges with trees and...

  16. Temperate non-breeding surveys - a key to shorebird conservation

    Science.gov (United States)

    Sue Thomas

    2005-01-01

    Completion of the United States and Canadian shorebird conservation plans recently identified and prioritized shorebird monitoring, management, and conservation needs in the Western Hemisphere. We present an emerging approach to monitor shorebird use of temperate non-breeding areas under the Program for Regional and International Shorebird Monitoring (PRISM). This...

  17. Tempered Water Lower Port Connector Structural Analysis Verification

    Energy Technology Data Exchange (ETDEWEB)

    CREA, B.A.

    2000-05-05

    Structural analysis of the lower port connection of the Tempered Water System of the Cold Vacuum Drying Facility was performed. Subsequent detailed design changes to enhance operability resulted in the need to re-evaluate the bases of the original analysis to verify its continued validity. This evaluation is contained in Appendix A of this report. The original evaluation is contained in Appendix B.

  18. Late Glacial and Holocene Paleoliminology of two temperate lakes ...

    Indian Academy of Sciences (India)

    The stable carbon isotope (13C) and elemental C/N ratios in Total Organic Carbon (TOC) extracted from radiometrically dated cores from two Midwestern USA lakes were determined to investigate the factors that control these values in temperate lakes. The range of 13C values ( -26 to -32%) and C/N ratios (mean value ...

  19. Temperate forest dynamics and carbon storage: A 26-year case ...

    African Journals Online (AJOL)

    Temperate forests are globally important carbon stores that are, in the face of recent improvements in their conservation, likely to increase their storage capacity in the future. Despite this, these ecosystems are poorly understood, especially over longer time periods. To remedy this and to better understand these important ...

  20. Effect of tempering after cryogenic treatment of tungsten carbide ...

    Indian Academy of Sciences (India)

    Cryogenic treatment is a recent advancement in the field of machining to improve the properties of cutting tool materials. Tungsten carbide is the most commonly used cutting tool material in the industry and the technique can also be extended to it. Although the importance of tempering after cryogenic treatment has been ...

  1. Joint measurement of risk aversion, prudence, and temperance

    NARCIS (Netherlands)

    Ebert, S.; Wiesen, D.

    Risk aversion—but also the higher-order risk preferences of prudence and temperance—are fundamental concepts in the study of economic decision making. We propose a method to jointly measure the intensity of risk aversion, prudence, and temperance. Our theoretical approach is to define risk

  2. Silviculture for restoration of degraded temperate and boreal forests

    Science.gov (United States)

    John A. Stanturf; Palle Madsen; Emile S. Gardiner

    2004-01-01

    Throughout the temperate and boreal zones, human intervention has influenced landscapes and forests for millennia. The degree of human disturbance has only been constrained by the technology and resources available to different cultures and by time since initial habitation. Humans have influenced forests by regulating populations of browsers, clearing for agriculture,...

  3. Can polar bears use terrestrial foods to offset lost ice-based hunting opportunities?

    Science.gov (United States)

    Rode, Karyn D.; Robbins, Charles T.; Nelson, Lynne; Amstrup, Steven C.

    2015-01-01

    Increased land use by polar bears (Ursus maritimus) due to climate-change-induced reduction of their sea-ice habitat illustrates the impact of climate change on species distributions and the difficulty of conserving a large, highly specialized carnivore in the face of this global threat. Some authors have suggested that terrestrial food consumption by polar bears will help them withstand sea-ice loss as they are forced to spend increasing amounts of time on land. Here, we evaluate the nutritional needs of polar bears as well as the physiological and environmental constraints that shape their use of terrestrial ecosystems. Only small numbers of polar bears have been documented consuming terrestrial foods even in modest quantities. Over much of the polar bear's range, limited terrestrial food availability supports only low densities of much smaller, resident brown bears (Ursus arctos), which use low-quality resources more efficiently and may compete with polar bears in these areas. Where consumption of terrestrial foods has been documented, polar bear body condition and survival rates have declined even as land use has increased. Thus far, observed consumption of terrestrial food by polar bears has been insufficient to offset lost ice-based hunting opportunities but can have ecological consequences for other species. Warming-induced loss of sea ice remains the primary threat faced by polar bears.

  4. Habitat correlates of the red panda in the temperate forests of Bhutan.

    Directory of Open Access Journals (Sweden)

    Sangay Dorji

    Full Text Available Anthropogenic activities and associated global climate change are threatening the biodiversity in the Himalayas against a backdrop of poor knowledge of the region's threatened species. The red panda (Ailurus fulgens is a threatened mammal confined to the eastern Himalayas, and because of Bhutan's central location in the distributional range of red pandas, its forests are integral to the long-term viability of wild populations. Detailed habitat requirements of the red panda are largely speculative, and there is virtually no ecological information available on this species in Bhutan. Between 2007 and 2009, we established 615 presence/absence plots in a systematic sampling of resident habitat types within Jigme Dorji and Thrumshingla National Parks, Bhutan, to investigate broad and fine-scale red panda habitat associations. Additional locality records of red pandas were obtained from interviewing 664 park residents. Red pandas were generally confined to cool broadleaf and conifer forests from 2,110-4,389 m above sea level (asl, with the majority of records between 2,400-3,700 m asl on south and east-facing slopes. At a finer scale, multivariate analysis revealed that red pandas were strongly associated with old growth Bhutan Fir (Abies densa forest dominated by a dense cover of Yushania and Arundanaria bamboo with a high density of fallen logs and tree stumps at ground level; a high density of trees, dead snags, and rhododendron shrubs in the mid-storey; and locations that were close to water. Because Bhutan's temperate forests that encompass prime red panda habitat are also integral to human subsistence and socio-economic development, there exists an inadvertent conflict between the needs of people and red pandas. As such, careful sustainable management of Bhutan's temperate forests is necessary if a balance is to be met between the socioeconomic needs of people and the conservation goals for red pandas.

  5. Long-term Changes in Habitat Provision by a Temperate Benthic Bioconstructor Threatened by Extreme Events

    Science.gov (United States)

    Cocito, S.; Lombardi, C.

    2016-02-01

    In a wide range of temperate environmental settings, long-lived, carbonate benthic organisms provide the framework of biogenic constructions, which create and maintain habitats and ecological niches for many species. These physical structures provide living space which progressively increases as framework grows. In temperate waters, bryozoans can have reef-constructing roles, and can substitute for corals in abundance and structure. As all bioconstructional species, they are seriously threaten by climate changes and its consequences such as thermal anomalies. The present study provides an assessment of changes in habitat provision by a reef-forming bryozoan dominating sub-tidal rocky reefs in the Ligurian Sea (NW Mediterranean) through 9-year time. Large ellipsoidal foliaceous colonies of Pentapora fascialis were monitored in 12 replicated stations (area: 1 m2) at two depths (11 and 22 m) from 1997 to 2005. Variation of living space (i.e. empty colony spaces) was computed by using colony width and high recorded annually. Impacts and long-term consequences of the 1999 and 2003 thermal anomalies were evaluated as changes in empty colony spaces. Over the 9 year monitoring, living space resulted more abundant at the deep stations (2947±617 cm3) than at the shallow ones (1652±494 cm3). Rapid decline in living space (90% and 94% reduction at 11 and 22 m stations, respectively) following the 1999 event was mainly due to the necrosis and reduction of the largest colonies. Differently, after the 2003 thermal anomaly the living space decline occurred gradually during the following 2 years. Interestingly, between the two events, colonies at the deep stations regained living space to pre-disturbance level (5671±1862 cm3) showing higher resilience to disturbance. Detecting effects of extreme events on bioconstructions and associated biota will contribute to the assessment of biodiversity changes and to predict future changes in threatened marine ecosystems.

  6. Habitat correlates of the red panda in the temperate forests of Bhutan.

    Science.gov (United States)

    Dorji, Sangay; Vernes, Karl; Rajaratnam, Rajanathan

    2011-01-01

    Anthropogenic activities and associated global climate change are threatening the biodiversity in the Himalayas against a backdrop of poor knowledge of the region's threatened species. The red panda (Ailurus fulgens) is a threatened mammal confined to the eastern Himalayas, and because of Bhutan's central location in the distributional range of red pandas, its forests are integral to the long-term viability of wild populations. Detailed habitat requirements of the red panda are largely speculative, and there is virtually no ecological information available on this species in Bhutan. Between 2007 and 2009, we established 615 presence/absence plots in a systematic sampling of resident habitat types within Jigme Dorji and Thrumshingla National Parks, Bhutan, to investigate broad and fine-scale red panda habitat associations. Additional locality records of red pandas were obtained from interviewing 664 park residents. Red pandas were generally confined to cool broadleaf and conifer forests from 2,110-4,389 m above sea level (asl), with the majority of records between 2,400-3,700 m asl on south and east-facing slopes. At a finer scale, multivariate analysis revealed that red pandas were strongly associated with old growth Bhutan Fir (Abies densa) forest dominated by a dense cover of Yushania and Arundanaria bamboo with a high density of fallen logs and tree stumps at ground level; a high density of trees, dead snags, and rhododendron shrubs in the mid-storey; and locations that were close to water. Because Bhutan's temperate forests that encompass prime red panda habitat are also integral to human subsistence and socio-economic development, there exists an inadvertent conflict between the needs of people and red pandas. As such, careful sustainable management of Bhutan's temperate forests is necessary if a balance is to be met between the socioeconomic needs of people and the conservation goals for red pandas.

  7. Genome-based comparative analyses of Antarctic and temperate species of Paenibacillus.

    Directory of Open Access Journals (Sweden)

    Melissa Dsouza

    Full Text Available Antarctic soils represent a unique environment characterised by extremes of temperature, salinity, elevated UV radiation, low nutrient and low water content. Despite the harshness of this environment, members of 15 bacterial phyla have been identified in soils of the Ross Sea Region (RSR. However, the survival mechanisms and ecological roles of these phyla are largely unknown. The aim of this study was to investigate whether strains of Paenibacillus darwinianus owe their resilience to substantial genomic changes. For this, genome-based comparative analyses were performed on three P. darwinianus strains, isolated from gamma-irradiated RSR soils, together with nine temperate, soil-dwelling Paenibacillus spp. The genome of each strain was sequenced to over 1,000-fold coverage, then assembled into contigs totalling approximately 3 Mbp per genome. Based on the occurrence of essential, single-copy genes, genome completeness was estimated at approximately 88%. Genome analysis revealed between 3,043-3,091 protein-coding sequences (CDSs, primarily associated with two-component systems, sigma factors, transporters, sporulation and genes induced by cold-shock, oxidative and osmotic stresses. These comparative analyses provide an insight into the metabolic potential of P. darwinianus, revealing potential adaptive mechanisms for survival in Antarctic soils. However, a large proportion of these mechanisms were also identified in temperate Paenibacillus spp., suggesting that these mechanisms are beneficial for growth and survival in a range of soil environments. These analyses have also revealed that the P. darwinianus genomes contain significantly fewer CDSs and have a lower paralogous content. Notwithstanding the incompleteness of the assemblies, the large differences in genome sizes, determined by the number of genes in paralogous clusters and the CDS content, are indicative of genome content scaling. Finally, these sequences are a resource for further

  8. Genome-based comparative analyses of Antarctic and temperate species of Paenibacillus.

    Science.gov (United States)

    Dsouza, Melissa; Taylor, Michael W; Turner, Susan J; Aislabie, Jackie

    2014-01-01

    Antarctic soils represent a unique environment characterised by extremes of temperature, salinity, elevated UV radiation, low nutrient and low water content. Despite the harshness of this environment, members of 15 bacterial phyla have been identified in soils of the Ross Sea Region (RSR). However, the survival mechanisms and ecological roles of these phyla are largely unknown. The aim of this study was to investigate whether strains of Paenibacillus darwinianus owe their resilience to substantial genomic changes. For this, genome-based comparative analyses were performed on three P. darwinianus strains, isolated from gamma-irradiated RSR soils, together with nine temperate, soil-dwelling Paenibacillus spp. The genome of each strain was sequenced to over 1,000-fold coverage, then assembled into contigs totalling approximately 3 Mbp per genome. Based on the occurrence of essential, single-copy genes, genome completeness was estimated at approximately 88%. Genome analysis revealed between 3,043-3,091 protein-coding sequences (CDSs), primarily associated with two-component systems, sigma factors, transporters, sporulation and genes induced by cold-shock, oxidative and osmotic stresses. These comparative analyses provide an insight into the metabolic potential of P. darwinianus, revealing potential adaptive mechanisms for survival in Antarctic soils. However, a large proportion of these mechanisms were also identified in temperate Paenibacillus spp., suggesting that these mechanisms are beneficial for growth and survival in a range of soil environments. These analyses have also revealed that the P. darwinianus genomes contain significantly fewer CDSs and have a lower paralogous content. Notwithstanding the incompleteness of the assemblies, the large differences in genome sizes, determined by the number of genes in paralogous clusters and the CDS content, are indicative of genome content scaling. Finally, these sequences are a resource for further investigations into

  9. Polarized scintillator targets

    Science.gov (United States)

    van den Brandt, B.; Bunyatova, E. I.; Hautle, P.; Konter, J. A.; Mango, S.

    2000-05-01

    The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as "live" polarized targets in nuclear physics experiments.

  10. Polarized scintillator targets

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, B. van den E-mail: vandenbrandt@psi.ch; Bunyatova, E.I.; Hautle, P.; Konter, J.A.; Mango, S

    2000-05-21

    The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as 'live' polarized targets in nuclear physics experiments.

  11. GUIDE FOR POLARIZED NEUTRONS

    Science.gov (United States)

    Sailor, V.L.; Aichroth, R.W.

    1962-12-01

    The plane of polarization of a beam of polarized neutrons is changed by this invention, and the plane can be flipped back and forth quicitly in two directions in a trouble-free manner. The invention comprises a guide having a plurality of oppositely directed magnets forming a gap for the neutron beam and the gaps are spaced longitudinally in a spiral along the beam at small stepped angles. When it is desired to flip the plane of polarization the magnets are suitably rotated to change the direction of the spiral of the gaps. (AEC)

  12. Stress and deformation characteristics of sea ice in a high resolution numerical sea ice model.

    Science.gov (United States)

    Heorton, Harry; Feltham, Daniel; Tsamados, Michel

    2017-04-01

    The drift and deformation of sea ice floating on the polar oceans is due to the applied wind and ocean currents. The deformations of sea ice over ocean basin length scales have observable patterns; cracks and leads in satellite images and within the velocity fields generated from floe tracking. In a climate sea ice model the deformation of sea ice over ocean basin length scales is modelled using a rheology that represents the relationship between stresses and deformation within the sea ice cover. Here we investigate the link between observable deformation characteristics and the underlying internal sea ice stresses and force balance using the Los Alamos numerical sea ice climate model. In order to mimic laboratory experiments on the deformation of small cubes of sea ice we have developed an idealised square domain that tests the model response at spatial resolutions of up to 500m. We use the Elastic Anisotropic Plastic and Elastic Viscous Plastic rheologies, comparing their stability over varying resolutions and time scales. Sea ice within the domain is forced by idealised winds in order to compare the confinement of wind stresses and internal sea ice stresses. We document the characteristic deformation patterns of convergent, divergent and rotating stress states.

  13. Mapping of summer sea ice in the Chukchi Sea using KOMPSAT-5 wide swath SAR images

    Science.gov (United States)

    Han, H.; Kim, H. C.

    2016-12-01

    Synthetic Aperture Radar (SAR) has been widely used for mapping sea ice because it can observe Earth's surface regardless of sun altitudes and weather conditions. Korea Multi-Purpose SATellte-5 (KOMPSAT-5) is South Korea's first satellite equipped with X-band SAR system that provides high-resolution images in various observation modes. In this study, sea ice mapping model based on Random Forest (RF), a rule-based machine learning approach, was developed for KOMPSAT-5 Enhanced Wide (EW) swath SAR data obtained from August to September 2015 in the Chukchi Sea of the Arctic Ocean. All SAR images were acquired in HH-polarization at incidence angle ranging from 17 to 50°. Each SAR image covers the area of 100 km × 100 km. A total of 12 texture features derived from backscattering intensity and grey level co-occurrence matrix (GLCM) were used as input variables for sea ice mapping model. The sea ice mapping model based on the RF produced sea ice map with a grid size of 125 m, with the overall accuracy of 99.2% and the kappa coefficient of 98.5% in the classification of sea ice and open water. Sea ice concentration (SIC) was computed from the RF-derived sea ice maps and compared with that from the observations of two passive microwave sensors— the Special Sensor Microwave Imager/Sounder (SSMIS) and the Advanced Microwave Scanning Radiometer 2 (AMSR2). SSMIS and AMSR2 estimates SIC using the NASA Team (NT) and Turbulence Interaction STudy (ARTIST) Sea Ice (ASI) algorithm, respectively. The SSMIS NT SIC was underestimated in marginal ice zone and compact ice zone, while they were overestimated in sea ice edge. Meanwhile, the AMSR2 ASI SIC was underestimated in compact ice zone and overestimated in other regions. This research was funded by the Korea Polar Research Institute (KOPRI) under the project titled `SaTellite remote sensing on west Antarctic ocean Research (STAR) (PE16040)'.

  14. Groundwater flow modelling of periods with temperate climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Swan, David (Serco Technical Consulting Services (United Kingdom)); Marsic, Niko (Kemakta Konsult AB (Sweden)); Follin, Sven (SF GeoLogic AB (Sweden))

    2010-11-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  15. The Structure of Genetic Diversity in Eelgrass (Zostera marina L.) along the North Pacific and Bering Sea Coasts of Alaska

    Science.gov (United States)

    Talbot, Sandra; Sage, Kevin; Rearick, Jolene; Fowler, Megan C.; Muñiz-Salazar, Raquel; Baibak, Bethany; Wyllie-Echeverria, Sandy; Cabello-Pasini, Alehandro; Ward, David H.

    2016-01-01

    Eelgrass (Zostera marina) populations occupying coastal waters of Alaska are separated by a peninsula and island archipelago into two Large Marine Ecosystems (LMEs). From populations in both LMEs, we characterize genetic diversity, population structure, and polarity in gene flow using nuclear microsatellite fragment and chloroplast and nuclear sequence data. An inverse relationship between genetic diversity and latitude was observed (heterozygosity: R2 = 0.738, P < 0.001; allelic richness: R2 = 0.327, P = 0.047), as was significant genetic partitioning across most sampling sites (θ = 0.302, P < 0.0001). Variance in allele frequency was significantly partitioned by region only in cases when a population geographically in the Gulf of Alaska LME (Kinzarof Lagoon) was instead included with populations in the Eastern Bering Sea LME (θp = 0.128–0.172; P < 0.003), suggesting gene flow between the two LMEs in this region. Gene flow among locales was rarely symmetrical, with notable exceptions generally following net coastal ocean current direction. Genetic data failed to support recent proposals that multiple Zostera species (i.e. Z. japonica and Z. angustifolia) are codistributed with Z. marina in Alaska. Comparative analyses also failed to support the hypothesis that eelgrass populations in the North Atlantic derived from eelgrass retained in northeastern Pacific Last Glacial Maximum refugia. These data suggest northeastern Pacific populations are derived from populations expanding northward from temperate populations following climate amelioration at the terminus of the last Pleistocene glaciation.

  16. Soil phosphorus fractionation as a tool for monitoring dust phosphorus signature underneath a Blue Pine (Pinus wallichiana canopy in a Temperate Forest

    Directory of Open Access Journals (Sweden)

    Mustafa-Nawaz Shafqat

    2016-12-01

    Full Text Available Aims of the study: This study aims (i to monitor the amount of dust deposition during dry season in the moist temperate forest; (ii to study nature of P fractions in the dust samples falling on the trees in the region; (iii to study soil P fractions as influenced by the processes of throughfall and stemflow of a Blue Pine (Pinus wallichiana canopy and to finger print the contribution of dust towards P input in the temperate forest ecosystem. Area of study: The site used for the collection of soil samples was situated at an elevation of 6900 feet above sea levels (temperate forest in Himalaya region in the Thandani area national forest located in the north west of Pakistan. Material and methods:  For soil sampling and processing, three forest sites with three old tree plants per site were selected at approximately leveled plain for surface soil sampling. Two dust samples were collected and analyzed for different physicochemical properties along with different P fractions. First dust sample was collected from a site situated at an elevation of 4000 feet and second one was collected from an elevation of 6500 feet above sea levels. Modified Hedley procedure for the fractionation of P in the dust and soil samples were used. Main results: The input of dust was 43 and 20 kg ha-1 during drier months of the year (September-June at lower and higher elevation sites respectively, and the dust from lower elevation site had relative more all P fractions than the other dust sample. However, HCl-Pi fraction was dominant in both samples. Both labile (water plus NaHCO3 and non-labile (NaOH plus HCl inorganic P (Pi fractions were significantly increased in the surface soil by both stemflow and throughfall compared to the open field soil. The buildup of NaOH and HCl-Pi pools in soils underneath the canopy might prove useful in fingerprinting the contribution of atmospheric dust towards P cycling in this temperate forest. Research highlights: The role of dust in

  17. Coordenadas polares: curvas maravillosas

    OpenAIRE

    Norberto Jaime Chau Pérez; Roy Wil Sánchez Gutiérrez

    2010-01-01

    Se presenta una actividad colaborativa en la que se trabaja el tema coordenadas polares. Se presentan los objetivos de aprendizaje, el desarrollo de la actividad, los conocimientos previos necesarios y recomendaciones para una aplicación posterior.

  18. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  19. Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications

    Science.gov (United States)

    DeWeaver, Eric T.; Bitz, Cecilia M.; Tremblay, L.-Bruno

    This volume addresses the rapid decline of Arctic sea ice, placing recent sea ice decline in the context of past observations, climate model simulations and projections, and simple models of the climate sensitivity of sea ice. Highlights of the work presented here include • An appraisal of the role played by wind forcing in driving the decline; • A reconstruction of Arctic sea ice conditions prior to human observations, based on proxy data from sediments; • A modeling approach for assessing the impact of sea ice decline on polar bears, used as input to the U.S. Fish and Wildlife Service's decision to list the polar bear as a threatened species under the Endangered Species Act; • Contrasting studies on the existence of a "tipping point," beyond which Arctic sea ice decline will become (or has already become) irreversible, including an examination of the role of the small ice cap instability in global warming simulations; • A significant summertime atmospheric response to sea ice reduction in an atmospheric general circulation model, suggesting a positive feedback and the potential for short-term climate prediction. The book will be of interest to researchers attempting to understand the recent behavior of Arctic sea ice, model projections of future sea ice loss, and the consequences of sea ice loss for the natural and human systems of the Arctic.

  20. EDITORIAL: Polarization Optics

    Science.gov (United States)

    Turunen, Jari; Friesem, Asher A.; Friberg, Ari T.

    2004-03-01

    This special issue on Polarization Optics contains one review article and 23 research papers, many of which are based on presentations at the International Commission for Optics Topical Meeting on Polarization Optics, held in Polvijärvi, Finland, between 30 June and 3 July 2003. While this issue should not in any sense be considered as a `proceedings' of this meeting, the possibility of submitting papers to it was widely advertised during the meeting, which was attended by a large fraction of prominent scientists in the field of polarization optics. Thus the quality of papers in this special issue is high. In announcing both the meeting and this special issue, we emphasized that the concept of `polarization optics' should be understood in a wide sense. In fact, all contributions dealing with the vectorial nature of light were welcome. As a result, the papers included here cover a wide range of different aspects of linear and nonlinear polarization optics. Both theoretical and experimental features are discussed. We are pleased to see that the conference and this special issue both reflect the wide diversity of important and novel polarization phenomena in optics. The papers in this special issue, and other recently published works, demonstrate that even though polarization is a fundamental property of electromagnetic fields, interest in it is rapidly increasing. The fundamental relations between partial coherence and partial polarization are currently under vigorous research in electromagnetic coherence theory. In diffractive optics it has been found that the exploitation of the vectorial nature of light can be of great benefit. Fabrication of sophisticated, spatially variable polarization-control elements is becoming possible with the aid of nanolithography. Polarization singularities and the interplay of bulk properties and topology in nanoscale systems have created much enthusiasm. In nonlinear optics, the second harmonic waves generated on reflection and

  1. Polarization Versus Agglomeration

    OpenAIRE

    Martinho, Vítor João Pereira Domingues

    2011-01-01

    The aim of this paper is to analyze the processes of polarization and agglomeration, to explain the mechanisms and causes of these phenomena in order to identify similarities and differences. As the main implication of this study should be noted that both process pretend to explain the concentration of economic activity and population in certain places, through cumulative phenomena, but with different perspectives, in other words, the polarization with a view of economic development and agglo...

  2. Polar Cap Patch Dynamics

    Science.gov (United States)

    2013-04-25

    associated with the rotation of the extreme density may in itself lead to a stronger growth of ionospheric irregularities . These irregularities may...continue to grow all the way across the polar cap. The result is more efficient creation of ionospheric irregularities . Title 4: Motion of polar...the cusp ionosphere over Svalbard to investigate the production of decameter scale irregularities in the electron plasma associated with HF radar

  3. Regulation of osteoclast polarization.

    Science.gov (United States)

    Takahashi, Naoyuki; Ejiri, Sadakazu; Yanagisawa, Shigeru; Ozawa, Hidehiro

    2007-07-01

    Osteoclast function consists of several processes: recognition of mineralized tissues, development of ruffled borders and sealing zones, secretion of acids and proteolytic enzymes into the space beneath the ruffled border, and incorporation and secretion of bone degradation products using the transcytosis system. One of the most important questions concerning osteoclast function is how osteoclasts recognize bone and polarize. During the past decade, new approaches have been taken to investigate the regulation of osteoclast polarization. Attachment of osteoclasts to some proteins containing the Arg-Gly-Asp sequence motif through vitronectin receptors is the first step in inducing the polarization of osteoclasts. Physical properties of bone such as hardness or roughness are also required to induce osteoclast polarity. Osteoclasts cultured even on plastic dishes secrete protons toward the dish surface, suggesting that osteoclasts recognize plastic as a mineralized matrix and secrete protons. This notion was supported by the recent findings that bisphosphonates and reveromycin A were specifically incorporated into polarized osteoclasts cultured even on plastic dishes. On the other hand, a sealing zone, defined as a thick band of actin, is induced in osteoclasts adherent only on an apatite-containing mineralized matrix. These results suggest that osteoclasts recognize physical properties of the mineralized tissue to secrete protons, and also sense apatite itself or components of apatite to form the sealing zone. Here, we review recent findings on the regulation of osteoclast polarization. We also discuss how osteoclasts recognize mineralized tissues to form the sealing zone.

  4. Polarizations on abelian varieties

    Science.gov (United States)

    Silverberg, A.; Zarhin, Yu. G.

    2002-09-01

    Every isogeny class over an algebraically closed field contains a principally polarized abelian variety ([10, corollary 1 to theorem 4 in section 23]). Howe ([3]; see also [4]) gave examples of isogeny classes of abelian varieties over finite fields with no principal polarizations (but not with the degrees of all the polarizations divisible by a given non-zero integer, as in Theorem 1·1 below). In [17] we obtained, for all odd primes [script l], isogeny classes of abelian varieties in positive characteristic, all of whose polarizations have degree divisible by [script l]2. We gave results in the more general context of invertible sheaves; see also Theorems 6·1 and 5·2 below. Our results gave the first examples for which all the polarizations of the abelian varieties in an isogeny class have degree divisible by a given prime. Inspired by our results in [17], Howe [5] recently obtained, for all odd primes [script l], examples of isogeny classes of abelian varieties over fields of arbitrary characteristic different from [script l] (including number fields), all of whose polarizations have degree divisible by [script l]2.

  5. Status of Marine Biodiversity of the China Seas

    Science.gov (United States)

    2013-01-01

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

  6. Status of marine biodiversity of the China seas.

    Directory of Open Access Journals (Sweden)

    J Y Liu

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

  7. Status of marine biodiversity of the China seas.

    Science.gov (United States)

    Liu, J Y

    2013-01-01

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

  8. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  9. Polarization Ratio Determination with Two Identical Linearly Polarized Antennas

    Science.gov (United States)

    2017-01-17

    Fourier transform analysis of 21 measurements with one of the antennas rotating about its axis a circular polarization ratio is derived which can be... transformed into an equivalent linear polarization ratio. A linearly polarized reference antenna is not required. The technique was verified by...systems the polarization ratio of an an- tenna is of interest for potential frequency / polarization re-use. Newell [1] and Joy [2] developed the three

  10. Stimulated electromagnetic emission polarization under different polarizations of pump waves

    OpenAIRE

    E. D. Tereshchenko; R. Y. Yurik; Baddeley, L.

    2015-01-01

    The results of investigations into the stimulated electromagnetic emission (SEE) polarization under different modes of the pump wave polarization are presented. The present results were obtained in November 2012 during a heating campaign utilizing the SPEAR (Space Plasma Exploration by Active Radar) heating facility, transmitting in both O- and X-mode polarization, and a PGI (Polar Geophysical Institute) radio interferometer capable of recording the polarization of the recei...

  11. Predicting 21st-century polar bear habitat distribution from global climate models

    Science.gov (United States)

    Durner, G.M.; Douglas, D.C.; Nielson, R.M.; Amstrup, Steven C.; McDonald, T.L.; Stirling, I.; Mauritzen, Mette; Born, E.W.; Wiig, O.; Deweaver, E.; Serreze, M.C.; Belikov, Stanislav; Holland, M.M.; Maslanik, J.; Aars, Jon; Bailey, D.A.; Derocher, A.E.

    2009-01-01

    Projections of polar bear (Ursus maritimus) sea ice habitat distribution in the polar basin during the 21st century were developed to understand the consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellitecollared polar bears and environmental data (e.g., bathymetry, distance to coastlines, and sea ice) collected from 1985 to 1995 to build resource selection functions (RSFs). RSFs described habitats that polar bears preferred in summer, autumn, winter, and spring. When applied to independent data from 1996 to 2006, the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st-century sea ice concentration projected by 10 general circulation models (GCMs) used in the Intergovernmental Panel of Climate Change Fourth Assessment Report, under the A1B greenhouse gas forcing scenario. Despite variation in their projections, all GCMs indicated habitat losses in the polar basin during the 21st century. Losses in the highest-valued RSF habitat (optimal habitat) were greatest in the southern seas of the polar basin, especially the Chukchi and Barents seas, and least along the Arctic Ocean shores of Banks Island to northern Greenland. Mean loss of optimal polar bear habitat was greatest during summer; from an observed 1.0 million km2 in 1985-1995 (baseline) to a projected multi-model mean of 0.32 million km2 in 2090-2099 (-68% change). Projected winter losses of polar bear habitat were less: from 1.7 million km2 in 1985-1995 to 1.4 million km2 in 2090-2099 (-17% change). Habitat losses based on GCM multi-model means may be conservative; simulated rates of habitat loss during 1985-2006 from many GCMs were less than the actual observed rates of loss. Although a reduction in the total amount of optimal habitat will likely reduce polar bear populations, exact relationships between habitat losses and population demographics remain unknown. Density and energetic

  12. The sea urchin – the ultimate herbivore and biogeographic variability in its ability to deforest kelp ecosystems

    OpenAIRE

    Byrnes, Jarrett E.; Johnson, Ladd E.; Connell, Sean D.; Shears, Nick T.; McMillan, Selena M.; Irving, Andrew; Buschmann, Alejandro H.; Graham, Michael H.; Kinlan, Brian P.

    2013-01-01

    Barren rocky seafloor landscapes, denuded of almost all life by ravenous sea urchins, liberated from their predators, stands as one of the iconic images of trophic cascades in Ecology. While this paradigm has been cited in nearly every temperate rocky reef ecosystem across the globe, there is widespread disagreement as to its generality. Given their biology, sea urchins are clearly one of the ocean’s strongest herbivores in many systems, but where will their impact be strongest? Here we perfo...

  13. Comparative exploration of hydrogen sulfide and water transmembrane free energy surfaces via orthogonal space tempering free energy sampling.

    Science.gov (United States)

    Lv, Chao; Aitchison, Erick W; Wu, Dongsheng; Zheng, Lianqing; Cheng, Xiaolin; Yang, Wei

    2016-03-05

    Hydrogen sulfide (H2 S), a commonly known toxic gas compound, possesses unique chemical features that allow this small solute molecule to quickly diffuse through cell membranes. Taking advantage of the recent orthogonal space tempering (OST) method, we comparatively mapped the transmembrane free energy landscapes of H2 S and its structural analogue, water (H2 O), seeking to decipher the molecular determinants that govern their drastically different permeabilities. As revealed by our OST sampling results, in contrast to the highly polar water solute, hydrogen sulfide is evidently amphipathic, and thus inside membrane is favorably localized at the interfacial region, that is, the interface between the polar head-group and nonpolar acyl chain regions. Because the membrane binding affinity of H2 S is mainly governed by its small hydrophobic moiety and the barrier height inbetween the interfacial region and the membrane center is largely determined by its moderate polarity, the transmembrane free energy barriers to encounter by this toxic molecule are very small. Moreover when H2 S diffuses from the bulk solution to the membrane center, the above two effects nearly cancel each other, so as to lead to a negligible free energy difference. This study not only explains why H2 S can quickly pass through cell membranes but also provides a practical illustration on how to use the OST free energy sampling method to conveniently analyze complex molecular processes. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  14. The old man and the sea.

    Energy Technology Data Exchange (ETDEWEB)

    Geesaman, D. F. (Physics)

    2010-01-01

    The summary of this presentation is: (1) the origin and structure of the sea remain critical themes in the physics of the nucleon and nucleus; (2) We need to push to higher x values and E906/SeaQuest is especially well suited for this. We start this summer and run for two years; (3) The other really key measurement is improved precision in the spin carried by the sea quarks and the spin-correlations in the sea - COMPASS, RHIC, J-PARC, JLAB 12 GeV.; and (4) This is difficult and may require the next generation of polarized Drell-Yan experiments. Whatever we measure, Tony Thomas will have thought of it first and helped stimulate the experiments.

  15. Polarization: A Must for Fusion

    Directory of Open Access Journals (Sweden)

    Guidal M.

    2012-10-01

    Full Text Available Recent realistic simulations confirm that the polarization of the fuel would improve significantly the DT fusion efficiency. We have proposed an experiment to test the persistence of the polarization in a fusion process, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a 3He and a neutron in the final state. The angular distribution of the neutrons and the change in the corresponding total cross section are related to the polarization persistence. The experimental polarization of DT fuel is a technological challenge. Possible paths for Magnetic Confinement Fusion (MCF and for Inertial Confinement Fusion (ICF are reviewed. For MCF, polarized gas can be used. For ICF, cryogenic targets are required. We consider both, the polarization of gas and the polarization of solid DT, emphasizing the Dynamic Nuclear polarization (DNP of HD and DT molecules.

  16. AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature (Tb) Polar Grids V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The AMSR-E/Aqua Level-3 6.25 km daily sea ice product includes 89.0 GHz brightness temperature averages (daily, ascending, and descending) on a 6.25 km polar...

  17. Immigration, dissemination and ecology of Elminius modestus Darwin in the North Sea, especially along the Dutch Coast

    NARCIS (Netherlands)

    Hartog, den C.

    1953-01-01

    In 1947, Bishop was the first to pay attention to the occurrence of the barnacle Elminius modestus Darwin in British waters. This barnacle, which is a native of the coasts of southern and eastern Australia and New Zealand, i.e. of the temperate seas of the southern hemisphere, had been found by him

  18. Photon polarization in np fusion

    CERN Document Server

    Ramachandran, G; Kumar, S P

    2003-01-01

    A model-independent irreducible tensor formalism is developed to discuss photon polarization in np fusion. It is shown that photon polarization arising out of the interference of the dominant isovector M1 amplitude at thermal neutron energies with the small isoscalar M1 and E2 amplitudes can be studied with advantage in suitably designed polarized beam and polarized target experiments, where the neutron and proton polarizations are either opposite to each other or orthogonal to each other. (letter to the editor)

  19. Interspecific variation in total phenolic content in temperate brown algae

    Directory of Open Access Journals (Sweden)

    Anna Maria Mannino

    2017-09-01

    Full Text Available Marine algae synthesize secondary metabolites such as polyphenols that function as defense and protection mechanisms. Among brown algae, Fucales and Dictyotales (Phaeophyceae contain the highest levels of phenolic compounds, mainly phlorotannins, that play multiple roles. Four temperate brown algae (Cystoseira amentacea, Cystoseira compressa, Dictyopteris polypodioides and Padina pavonica were studied for total phenolic contents. Total phenolic content was determined colorimetrically with the Folin-Ciocalteu reagent. Significant differences in total phenolic content were observed between leathery and sheetlike algae and also within each morphological group. Among the four species, the sheet-like alga D. polypodioides, living in the upper infralittoral zone, showed the highest concentration of phenolic compounds. These results are in agreement with the hypothesis that total phenolic content in temperate brown algae is influenced by a combination of several factors, such as growth form, depth, and exposition to solar radiation.

  20. Bifurcation dynamics of the tempered fractional Langevin equation.

    Science.gov (United States)

    Zeng, Caibin; Yang, Qigui; Chen, YangQuan

    2016-08-01

    Tempered fractional processes offer a useful extension for turbulence to include low frequencies. In this paper, we investigate the stochastic phenomenological bifurcation, or stochastic P-bifurcation, of the Langevin equation perturbed by tempered fractional Brownian motion. However, most standard tools from the well-studied framework of random dynamical systems cannot be applied to systems driven by non-Markovian noise, so it is desirable to construct possible approaches in a non-Markovian framework. We first derive the spectral density function of the considered system based on the generalized Parseval's formula and the Wiener-Khinchin theorem. Then we show that it enjoys interesting and diverse bifurcation phenomena exchanging between or among explosive-like, unimodal, and bimodal kurtosis. Therefore, our procedures in this paper are not merely comparable in scope to the existing theory of Markovian systems but also provide a possible approach to discern P-bifurcation dynamics in the non-Markovian settings.

  1. Bifurcation dynamics of the tempered fractional Langevin equation

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Caibin, E-mail: macbzeng@scut.edu.cn; Yang, Qigui, E-mail: qgyang@scut.edu.cn [School of Mathematics, South China University of Technology, Guangzhou 510640 (China); Chen, YangQuan, E-mail: ychen53@ucmerced.edu [MESA LAB, School of Engineering, University of California, Merced, 5200 N. Lake Road, Merced, California 95343 (United States)

    2016-08-15

    Tempered fractional processes offer a useful extension for turbulence to include low frequencies. In this paper, we investigate the stochastic phenomenological bifurcation, or stochastic P-bifurcation, of the Langevin equation perturbed by tempered fractional Brownian motion. However, most standard tools from the well-studied framework of random dynamical systems cannot be applied to systems driven by non-Markovian noise, so it is desirable to construct possible approaches in a non-Markovian framework. We first derive the spectral density function of the considered system based on the generalized Parseval's formula and the Wiener-Khinchin theorem. Then we show that it enjoys interesting and diverse bifurcation phenomena exchanging between or among explosive-like, unimodal, and bimodal kurtosis. Therefore, our procedures in this paper are not merely comparable in scope to the existing theory of Markovian systems but also provide a possible approach to discern P-bifurcation dynamics in the non-Markovian settings.

  2. Frost flowers and sea-salt aerosols over seasonal sea-ice areas in northwestern Greenland during winter–spring

    Directory of Open Access Journals (Sweden)

    K. Hara

    2017-07-01

    Full Text Available Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl−, Mg2+, K+, Ca2+, Br−, and iodine. Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14–3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl−, Br−, and iodine in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS SO42−. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

  3. Frost flowers and sea-salt aerosols over seasonal sea-ice areas in northwestern Greenland during winter-spring

    Science.gov (United States)

    Hara, Keiichiro; Matoba, Sumito; Hirabayashi, Motohiro; Yamasaki, Tetsuhide

    2017-07-01

    Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl-, Mg2+, K+, Ca2+, Br-, and iodine). Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14-3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl-, Br-, and iodine) in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS) SO42-. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine) on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

  4. Round herring (genus Etrumeus) contain distinct evolutionary lineages coincident with a biogeographic barrier along Australia’s southern temperate coastline

    KAUST Repository

    DiBattista, Joseph

    2014-08-28

    Molecular genetic surveys of marine fishes have revealed that some widely distributed species are actually a composite of multiple evolutionary lineages. This is apparent in the round herrings (genus Etrumeus), wherein a globally distributed taxon (Etrumeus sadina Mitchill 1814) has proven to contain at least seven valid taxa, with more likely awaiting discovery. Here, we survey evolutionary lineages of the nominal E. sadina (formerly E. teres, a junior synonym) across the southern temperate zone of Australia, a marine region divided into three biogeographic provinces based primarily on the distribution of intertidal faunas. Results from morphological and mitochondrial DNA data reveal two evolutionary lineages corresponding to eastern and southwestern provinces (d = 0.007 for cytochrome c oxidase subunit I and d = 0.017 for cytochrome b), possibly initiated by the Bassian Isthmus between Australia and Tasmania during low sea-level stands. The Australian round herring is also genetically distinct from the nearest congeneric forms in the Indian and Pacific Oceans, with a corresponding modal difference in gill-raker counts in most cases. Based on these data, we resurrect the title Etrumeus jacksoniensis for the Australian round herring. While the Bassian Isthmus may have initiated the partition of evolutionary lineages within Australia, additional oceanographic and ecological factors must reinforce this separation in order to maintain diagnostic genetic differences along a continuous temperate coastline. © 2014 Springer-Verlag Berlin Heidelberg.

  5. Tropical fishes dominate temperate reef fish communities within western Japan.

    Science.gov (United States)

    Nakamura, Yohei; Feary, David A; Kanda, Masaru; Yamaoka, Kosaku

    2013-01-01

    Climate change is resulting in rapid poleward shifts in the geographical distribution of tropical and subtropical fish species. We can expect that such range shifts are likely to be limited by species-specific resource requirements, with temperate rocky reefs potentially lacking a range of settlement substrates or specific dietary components important in structuring the settlement and success of tropical and subtropical fish species. We examined the importance of resource use in structuring the distribution patterns of range shifting tropical and subtropical fishes, comparing this with resident temperate fish species within western Japan (Tosa Bay); the abundance, diversity, size class, functional structure and latitudinal range of reef fishes utilizing both coral reef and adjacent rocky reef habitat were quantified over a 2 year period (2008-2010). This region has undergone rapid poleward expansion of reef-building corals in response to increasing coastal water temperatures, and forms one of the global hotspots for rapid coastal changes. Despite the temperate latitude surveyed (33°N, 133°E) the fish assemblage was both numerically, and in terms of richness, dominated by tropical fishes. Such tropical faunal dominance was apparent within both coral, and rocky reef habitats. The size structure of the assemblage suggested that a relatively large number of tropical species are overwintering within both coral and rocky habitats, with a subset of these species being potentially reproductively active. The relatively high abundance and richness of tropical species with obligate associations with live coral resources (i.e., obligate corallivores) shows that this region holds the most well developed temperate-located tropical fish fauna globally. We argue that future tropicalisation of the fish fauna in western Japan, associated with increasing coral habitat development and reported increasing shifts in coastal water temperatures, may have considerable positive economic

  6. First description of underwater acoustic diversity in three temperate ponds

    Directory of Open Access Journals (Sweden)

    Camille Desjonquères

    2015-11-01

    Full Text Available The past decade has produced an increased ecological interest in sonic environments, or soundscapes. However, despite this rise in interest and technological improvements that allow for long-term acoustic surveys in various environments, some habitats’ soundscapes remain to be explored. Ponds, and more generally freshwater habitats, are one of these acoustically unexplored environments. Here we undertook the first long term acoustic monitoring of three temperate ponds in France. By aural and visual inspection of a selection of recordings, we identified 48 different sound types, and according to the rarefaction curves we calculated, more sound types are likely present in one of the three ponds. The richness of sound types varied significantly across ponds. Surprisingly, there was no pond-to-pond daily consistency of sound type richness variation; each pond had its own daily patterns of activity. We also explored the possibility of using six acoustic diversity indices to conduct rapid biodiversity assessments in temperate ponds. We found that all indices were sensitive to the background noise as estimated through correlations with the signal-to-noise ratio (SNR. However, we determined that the AR index could be a good candidate to measure acoustic diversities using partial correlations with the SNR as a control variable. Yet, research is still required to automatically compute the SNR in order to apply this index on a large data set of recordings. The results showed that these three temperate ponds host a high level of acoustic diversity in which the soundscapes were variable not only between but also within the ponds. The sources producing this diversity of sounds and the drivers of difference in daily song type richness variation both require further investigation. Such research would yield insights into the biodiversity and ecology of temperate ponds.

  7. Increase in forest growth: new evidences from temperate forests

    Directory of Open Access Journals (Sweden)

    Lingua E

    2010-07-01

    Full Text Available A paper recently published on PNAS provides a new evidence for an increase in forest growth in temperate forests. The possible causes of this process are discussed. The results show a relation between this change in tree growth with the increase in atmospheric CO2 concentration, temperature, and length of growth season. A better understanding of the specific mechanisms involved and the assessment of the consequences on the current and future global changes are needed.

  8. Tropical Fishes Dominate Temperate Reef Fish Communities within Western Japan

    OpenAIRE

    Yohei Nakamura; Feary, David A.; Masaru Kanda; Kosaku Yamaoka

    2013-01-01

    Climate change is resulting in rapid poleward shifts in the geographical distribution of tropical and subtropical fish species. We can expect that such range shifts are likely to be limited by species-specific resource requirements, with temperate rocky reefs potentially lacking a range of settlement substrates or specific dietary components important in structuring the settlement and success of tropical and subtropical fish species. We examined the importance of resource use in structuring t...

  9. Groundwater flow modelling of periods with temperate climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David (Serco Technical Consulting Services (United Kingdom)); Gylling, Bjoern; Marsic, Niko (Kemakta Konsult AB, Stockholm (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  10. The Research and Application of Webpage Temper-proofing System

    OpenAIRE

    Wang Yongquan; Wu Beihua

    2012-01-01

    With the sharp increase of hacking attacks over the last couple of years, web application security has become a key concern. The attack to websites, especially the explosion of webpage interpolating incidents has becomeone of the most serious problems of it. In this paper, the system adopts Web server core embedded technology to imbed tamper detection module and application protection module into the Web server, define correspondingstrategies for temper-proofing, and realize the real-time m...

  11. Computer simulation of quenched and tempered steel properties

    OpenAIRE

    B. Smoljan; D. Iljkić; Novak, H.

    2011-01-01

    Purpose: The algorithm of estimation of mechanical properties based on steel hardness has been established.Design/methodology/approach: Numerical modelling of hardness distribution in as-quenched steel specimen was performed by involving the results of simple experimental test, i.e., Jominy-test. Hardness of quenched and tempered steel has been expressed as function of maximal hardness of actual steel and hardness of actual steel with 50% of martensite in microstructure, according to the time...

  12. First description of underwater acoustic diversity in three temperate ponds

    Science.gov (United States)

    Rybak, Fanny; Depraetere, Marion; Gasc, Amandine; Le Viol, Isabelle; Pavoine, Sandrine; Sueur, Jérôme

    2015-01-01

    The past decade has produced an increased ecological interest in sonic environments, or soundscapes. However, despite this rise in interest and technological improvements that allow for long-term acoustic surveys in various environments, some habitats’ soundscapes remain to be explored. Ponds, and more generally freshwater habitats, are one of these acoustically unexplored environments. Here we undertook the first long term acoustic monitoring of three temperate ponds in France. By aural and visual inspection of a selection of recordings, we identified 48 different sound types, and according to the rarefaction curves we calculated, more sound types are likely present in one of the three ponds. The richness of sound types varied significantly across ponds. Surprisingly, there was no pond-to-pond daily consistency of sound type richness variation; each pond had its own daily patterns of activity. We also explored the possibility of using six acoustic diversity indices to conduct rapid biodiversity assessments in temperate ponds. We found that all indices were sensitive to the background noise as estimated through correlations with the signal-to-noise ratio (SNR). However, we determined that the AR index could be a good candidate to measure acoustic diversities using partial correlations with the SNR as a control variable. Yet, research is still required to automatically compute the SNR in order to apply this index on a large data set of recordings. The results showed that these three temperate ponds host a high level of acoustic diversity in which the soundscapes were variable not only between but also within the ponds. The sources producing this diversity of sounds and the drivers of difference in daily song type richness variation both require further investigation. Such research would yield insights into the biodiversity and ecology of temperate ponds. PMID:26587351

  13. Small Sample Sizes Yield Biased Allometric Equations in Temperate Forests

    OpenAIRE

    Duncanson, L.; Rourke, O.; Dubayah, R.

    2015-01-01

    Accurate quantification of forest carbon stocks is required for constraining the global carbon cycle and its impacts on climate. The accuracies of forest biomass maps are inherently dependent on the accuracy of the field biomass estimates used to calibrate models, which are generated with allometric equations. Here, we provide a quantitative assessment of the sensitivity of allometric parameters to sample size in temperate forests, focusing on the allometric relationship between tree height a...

  14. Tropical fishes dominate temperate reef fish communities within western Japan.

    Directory of Open Access Journals (Sweden)

    Yohei Nakamura

    Full Text Available Climate change is resulting in rapid poleward shifts in the geographical distribution of tropical and subtropical fish species. We can expect that such range shifts are likely to be limited by species-specific resource requirements, with temperate rocky reefs potentially lacking a range of settlement substrates or specific dietary components important in structuring the settlement and success of tropical and subtropical fish species. We examined the importance of resource use in structuring the distribution patterns of range shifting tropical and subtropical fishes, comparing this with resident temperate fish species within western Japan (Tosa Bay; the abundance, diversity, size class, functional structure and latitudinal range of reef fishes utilizing both coral reef and adjacent rocky reef habitat were quantified over a 2 year period (2008-2010. This region has undergone rapid poleward expansion of reef-building corals in response to increasing coastal water temperatures, and forms one of the global hotspots for rapid coastal changes. Despite the temperate latitude surveyed (33°N, 133°E the fish assemblage was both numerically, and in terms of richness, dominated by tropical fishes. Such tropical faunal dominance was apparent within both coral, and rocky reef habitats. The size structure of the assemblage suggested that a relatively large number of tropical species are overwintering within both coral and rocky habitats, with a subset of these species being potentially reproductively active. The relatively high abundance and richness of tropical species with obligate associations with live coral resources (i.e., obligate corallivores shows that this region holds the most well developed temperate-located tropical fish fauna globally. We argue that future tropicalisation of the fish fauna in western Japan, associated with increasing coral habitat development and reported increasing shifts in coastal water temperatures, may have considerable

  15. Physics of polarized targets

    CERN Document Server

    Niinikoski, Tapio

    2014-01-01

    For developing, building and operating solid polarized targets we need to understand several fields of physics that have seen sub stantial advances during the last 50 years. W e shall briefly review a selection of those that are important today. These are: 1) quantum statistical methods to describe saturation and relaxation in magnetic resonance; 2) equal spin temperature model for dy namic nuclear polarization; 3 ) weak saturation during NMR polarization measurement; 4 ) refrigeration using the quantum fluid properties of helium isotopes. These, combined with superconducting magnet technologies, permit today to reach nearly complete pola rization of almost any nuclear spins. Targets can be operated in frozen spin mode in rather low and inhomogeneous field of any orientation, and in DNP mode in beams of high intensity. Beyond such experiments of nuclear and particle physics, applications a re also emerging in macromolecular chemistry and in magnetic resonance imaging. This talk is a tribute to Michel Borghini...

  16. Time Domain Induced Polarization

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest

    2012-01-01

    Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use......%. Furthermore, the presence of low-pass filters in time-domain-induced polarization instruments affects the early times of the acquired decays (typically up to 100 ms) and has to be modeled in the forward response to avoid significant loss of resolution. The developed forward code has been implemented in a 1D...... polarization response when compared to traditional integral chargeability inversion. The quality of the inversion results has been assessed by a complete uncertainty analysis of the model parameters; furthermore, borehole information confirm the outcomes of the field interpretations. With this new accurate...

  17. A lunar polar expedition

    Science.gov (United States)

    Dowling, Richard; Staehle, Robert L.; Svitek, Tomas

    1992-01-01

    Advanced exploration and development in harsh environments require mastery of basic human survival skill. Expeditions into the lethal climates of Earth's polar regions offer useful lessons for tommorrow's lunar pioneers. In Arctic and Antarctic exploration, 'wintering over' was a crucial milestone. The ability to establish a supply base and survive months of polar cold and darkness made extensive travel and exploration possible. Because of the possibility of near-constant solar illumination, the lunar polar regions, unlike Earth's may offer the most hospitable site for habitation. The World Space Foundation is examining a scenario for establishing a five-person expeditionary team on the lunar north pole for one year. This paper is a status report on a point design addressing site selection, transportation, power, and life support requirements.

  18. Convergence, Consilience, and the Evolution of Temperate Deciduous Forests.

    Science.gov (United States)

    Edwards, Erika J; Chatelet, David S; Chen, Bo-Chang; Ong, Jin Yao; Tagane, Shuichiro; Kanemitsu, Hironobu; Tagawa, Kazuki; Teramoto, Kentaro; Park, Brian; Chung, Kuo-Fang; Hu, Jer-Ming; Yahara, Tetsukazu; Donoghue, Michael J

    2017-08-01

    The deciduous habit of northern temperate trees and shrubs provides one of the most obvious examples of convergent evolution, but how did it evolve? Hypotheses based on the fossil record posit that deciduousness evolved first in response to drought or darkness and preadapted certain lineages as cold climates spread. An alternative is that evergreens first established in freezing environments and later evolved the deciduous habit. We monitored phenological patterns of 20 species of Viburnum spanning tropical, lucidophyllous (subtropical montane and warm temperate), and cool temperate Asian forests. In lucidophyllous forests, all viburnums were evergreen plants that exhibited coordinated leaf flushes with the onset of the rainy season but varied greatly in the timing of leaf senescence. In contrast, deciduous species exhibited tight coordination of both flushing and senescence, and we found a perfect correlation between the deciduous habit and prolonged annual freezing. In contrast to previous stepwise hypotheses, a consilience of independent lines of evidence supports a lockstep model in which deciduousness evolved in situ, in parallel, and concurrent with a gradual cooling climate. A pervasive selective force combined with the elevated evolutionary accessibility of a particular response may explain the massive convergence of adaptive strategies that characterizes the world's biomes.

  19. Biochar boosts tropical but not temperate crop yields

    Science.gov (United States)

    Jeffery, Simon; Abalos, Diego; Prodana, Marija; Catarina Bastos, Ana; van Groenigen, Jan Willem; Hungate, Bruce A.; Verheijen, Frank

    2017-05-01

    Applying biochar to soil is thought to have multiple benefits, from helping mitigate climate change [1, 2], to managing waste [3] to conserving soil [4]. Biochar is also widely assumed to boost crop yield [5, 6], but there is controversy regarding the extent and cause of any yield benefit [7]. Here we use a global-scale meta-analysis to show that biochar has, on average, no effect on crop yield in temperate latitudes, yet elicits a 25% average increase in yield in the tropics. In the tropics, biochar increased yield through liming and fertilization, consistent with the low soil pH, low fertility, and low fertilizer inputs typical of arable tropical soils. We also found that, in tropical soils, high-nutrient biochar inputs stimulated yield substantially more than low-nutrient biochar, further supporting the role of nutrient fertilization in the observed yield stimulation. In contrast, arable soils in temperate regions are moderate in pH, higher in fertility, and generally receive higher fertilizer inputs, leaving little room for additional benefits from biochar. Our findings demonstrate that the yield-stimulating effects of biochar are not universal, but may especially benefit agriculture in low-nutrient, acidic soils in the tropics. Biochar management in temperate zones should focus on potential non-yield benefits such as lime and fertilizer cost savings, greenhouse gas emissions control, and other ecosystem services.

  20. Winter climate change: a critical factor for temperate vegetation performance.

    Science.gov (United States)

    Kreyling, Juergen

    2010-07-01

    Winter ecological processes are important drivers of vegetation and ecosystem functioning in temperate ecosystems. There, winter conditions are subject to rapid climate change. The potential loss of a longer-lasting snow cover with implications to other plant-related climate parameters and overwintering strategies make the temperate zone particularly vulnerable to winter climate change. A formalized literature search in the ISI Web of Science shows that plant related research on the effects of winter climate change is generally underrepresented. Temperate regions in particular are rarely studied in this respect, although the few existing studies imply strong effects of winter climate change on species ranges, species compositions, phenology, or frost injury. The generally positive effect of warming on plant survival and production may be counteracted by effects such as an increased frost injury of roots and shoots, an increased insect pest risk, or a disrupted synchrony between plants and pollinators. Based on the literature study, gaps in current knowledge are discussed. Understanding the relative effects of interacting climate parameters, as well as a stronger consideration of shortterm events and variability of climatic conditions is urgent. With respect to plant response, it would be particularly worthwhile to account for hidden players such as pathogens, pollinators, herbivores, or fungal partners in mycorrhization.

  1. Frontiers in alley cropping: Transformative solutions for temperate agriculture.

    Science.gov (United States)

    Wolz, Kevin J; Lovell, Sarah T; Branham, Bruce E; Eddy, William C; Keeley, Keefe; Revord, Ronald S; Wander, Michelle M; Yang, Wendy H; DeLucia, Evan H

    2017-12-08

    Annual row crops dominate agriculture around the world and have considerable negative environmental impacts, including significant greenhouse gas emissions. Transformative land-use solutions are necessary to mitigate climate change and restore critical ecosystem services. Alley cropping (AC)-the integration of trees with crops-is an agroforestry practice that has been studied as a transformative, multifunctional land-use solution. In the temperate zone, AC has strong potential for climate change mitigation through direct emissions reductions and increases in land-use efficiency via overyielding compared to trees and crops grown separately. In addition, AC provides climate change adaptation potential and ecological benefits by buffering alley crops to weather extremes, diversifying income to hedge financial risk, increasing biodiversity, reducing soil erosion, and improving nutrient- and water-use efficiency. The scope of temperate AC research and application has been largely limited to simple systems that combine one timber tree species with an annual grain. We propose two frontiers in temperate AC that expand this scope and could transform its climate-related benefits: (i) diversification via woody polyculture and (ii) expanded use of tree crops for food and fodder. While AC is ready now for implementation on marginal lands, we discuss key considerations that could enhance the scalability of the two proposed frontiers and catalyze widespread adoption. © 2017 John Wiley & Sons Ltd.

  2. Grain boundary diffusion in terms of the tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sibatov, R.T., E-mail: ren_sib@bk.ru [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Svetukhin, V.V. [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Institute of Nanotechnology and Microelectronics of the Russian Academy of Sciences, 115487, 18 Nagatinskaya str., Moscow (Russian Federation)

    2017-06-28

    Mathematical treatment of grain-boundary diffusion based on the model first proposed by Fisher is usually formulated in terms of normal diffusion equations in a two-component nonhomogeneous medium. On the other hand, fractional equations of anomalous diffusion proved themselves to be useful in description of grain-boundary diffusion phenomena. Moreover, the most important propagation regime predicted by Fisher's model demonstrates subdiffusive behavior. However, the direct link between fractional approach and the Fisher model and its modifications has not found yet. Here, we fill this gap and show that solution of fractional subdiffusion equation offers general properties of classical solutions obtained by Whipple and Suzuoka. The tempered fractional approach is a convenient tool for studying precipitation in granular materials as the tempered subdiffusion limited process. - Highlights: • The link connected fractional diffusion approach and Fisher's model of grain-boundary diffusion is derived. • The subdiffusion exponent of grain-boundary diffusion can differ from 1/2. • Nucleation in granular materials is modeled by the process limited by tempered subdiffusion.

  3. Sliding mode controllers for a tempered glass furnace.

    Science.gov (United States)

    Almutairi, Naif B; Zribi, Mohamed

    2016-01-01

    This paper investigates the design of two sliding mode controllers (SMCs) applied to a tempered glass furnace system. The main objective of the proposed controllers is to regulate the glass plate temperature, the upper-wall temperature and the lower-wall temperature in the furnace to a common desired temperature. The first controller is a conventional sliding mode controller. The key step in the design of this controller is the introduction of a nonlinear transformation that maps the dynamic model of the tempered glass furnace into the generalized controller canonical form; this step facilitates the design of the sliding mode controller. The second controller is based on a state-dependent coefficient (SDC) factorization of the tempered glass furnace dynamic model. Using an SDC factorization, a simplified sliding mode controller is designed. The simulation results indicate that the two proposed control schemes work very well. Moreover, the robustness of the control schemes to changes in the system's parameters as well as to disturbances is investigated. In addition, a comparison of the proposed control schemes with a fuzzy PID controller is performed; the results show that the proposed SDC-based sliding mode controller gave better results. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  4. Polar oceans in a changing climate.

    Science.gov (United States)

    Barnes, David K A; Tarling, Geraint A

    2017-06-05

    Most of Earth's surface is blue or white, but how much of each would depend on the time of observation. Our planet has been through phases of snowball (all frozen), greenhouse (all liquid seas) and icehouse (frozen and liquid). Even during current icehouse conditions, the extent of ice versus water has changed considerably between ice ages and interglacial periods. Water has been vital for life on Earth and has driven and been influenced by transitions between greenhouse and icehouse. However, neither the possession of water nor having liquid and frozen seas are unique to Earth (Figure 1). Frozen water oceans on the moons Enceladus and Europa (and possibly others) and the liquid and frozen hydrocarbon oceans on Titan probably represent the most likely areas to find extraterrestrial life. We know very little about life in Earth's polar oceans, yet they are the engine of the thermohaline 'conveyor-belt', driving global circulation of heat, oxygen, carbon and nutrients as well as setting sea level through change in ice-mass balance. In regions of polar seas, where surface water is particularly cold and dense, it sinks to generate a tropic-ward flow on the ocean floor of the Pacific, Atlantic and Indian Oceans. Cold water holds more gas, so this sinking water exports O 2 and nutrients, thereby supporting life in the deep sea, as well as soaking up CO 2 from the atmosphere. Water from mid-depths at lower latitudes flows in to replace the sinking polar surface water. This brings heat. The poles are cold because they receive the least energy from the sun, and this extreme light climate varies on many different time scales. To us, the current warm, interglacial conditions seem normal, yet such phases have represented only ∼10% of Homo sapiens' existence. Variations in Earth's orbit (so called 'Milankovitch cycles') have driven cyclical alternation of glaciations (ice ages) and warmer interglacials. Despite this, Earth's polar regions have been our planet's most

  5. Comparative assessment of single and joint effects of diuron and Irgarol 1051 on Arctic and temperate microalgae using chlorophyll a fluorescence imaging

    KAUST Repository

    Kottuparambil, Sreejith

    2017-02-06

    Ship groundings and ice-breakers can cause pollution of the polar environment with antifouling biocides such as diuron and Irgarol 1051. The present study used pulse amplitude modulated fluorometry to compare single and joint toxicities of diuron and Irgarol 1051 on two freshwater taxa of microalgae (Chlorella and Chlamydomonas) originating from Arctic and temperate regions. 30min acute toxicity tests using chlorophyll a (Chl a) fluorescence revealed that Arctic strains of microalgae were more sensitive to herbicides than their temperate counterparts. Diuron and Irgarol 1051 had equal toxicities in the Arctic species, while Irgarol 1051 was more toxic (EC50=5.55–14.70μgL−1) than diuron (EC50=12.90–>40μgL−1) in the temperate species. Toxicity assessment of various mixtures of diuron and Irgarol 1051 revealed antagonistic, additive, and synergistic effects. Our data suggest that herbicides can adversely affect photosynthesis in Arctic microalgae at relatively low levels, and their impact can increase under complex mixture conditions.

  6. The possibility of tribopair lifetime extending by welding of quenched and tempered stainless steel with quenched and tempered carbon steel

    Directory of Open Access Journals (Sweden)

    V. Marušić

    2015-04-01

    Full Text Available In the conditions of tribocorrosion wear, extending of parts lifetime could be achieved by using stainless steel,which is hardened to sufficiently high hardness. In the tribosystem bolt/ bushing shell/link plate of the bucket elevator transporter conveyor machine, the previously quenched and tempered martensitic stainless steel for bolts is hardened at ≈47 HRC and welded with the quenched and tempered high yield carbon steel for bolts. Additional material, based on Cr-Ni-Mo (18/8/6 is used. The microstructure and hardness of welded samples are tested. On the tensile tester, resistance of the welded joint is tested with a simulated experiment. Dimensional control of worn tribosystem elements was performed after six months of service.

  7. The physics of polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    This course is intended to give a description of the basic physical concepts which underlie the study and the interpretation of polarization phenomena. Apart from a brief historical introduction (Sect. 1), the course is organized in three parts. A first part (Sects. 2 - 6) covers the most relevant facts about the polarization phenomena that are typically encountered in laboratory applications and in everyday life. In Sect. 2, the modern description of polarization in terms of the Stokes parameters is recalled, whereas Sect. 3 is devoted to introduce the basic tools of laboratory polarimetry, such as the Jones calculus and the Mueller matrices. The polarization phenomena which are met in the reflection and refraction of a beam of radiation at the separation surface between two dielectrics, or between a dielectric and a metal, are recalled in Sect. 4. Finally, Sect. 5 gives an introduction to the phenomena of dichroism and of anomalous dispersion and Sect. 6 summarizes the polarization phenomena that are commonly encountered in everyday life. The second part of this course (Sects. 7-14) deals with the description, within the formalism of classical physics, of the spectro-polarimetric properties of the radiation emitted by accelerated charges. Such properties are derived by taking as starting point the Liénard and Wiechert equations that are recalled and discussed in Sect. 7 both in the general case and in the non-relativistic approximation. The results are developed to find the percentage polarization, the radiation diagram, the cross-section and the spectral characteristics of the radiation emitted in different phenomena particularly relevant from the astrophysical point of view. The emission of a linear antenna is derived in Sect. 8. The other Sections are devoted to Thomson scattering (Sect. 9), Rayleigh scattering (Sect. 10), Mie scattering (Sect. 11), bremsstrahlung radiation (Sect. 12), cyclotron radiation (Sect. 13), and synchrotron radiation (Sect. 14

  8. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  9. Arctic and Antarctic sea ice and climate

    Science.gov (United States)

    Barreira, S.

    2014-12-01

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

  10. Climate change threatens polar bear populations: a stochastic demographic analysis.

    Science.gov (United States)

    Hunter, Christine M; Caswell, Hal; Runge, Michael C; Regehr, Eric V; Amstrup, Steve C; Stirling, Ian

    2010-10-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population

  11. Climate change threatens polar bear populations: A stochastic demographic analysis

    Science.gov (United States)

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

    2010-01-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in ?? in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log ??s, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log ??s ' - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic

  12. Recent carbonate sedimentation on Balearic platform: model for temperate-climate carbonate shelves

    Energy Technology Data Exchange (ETDEWEB)

    Fornos, J.; Rodriguez-Perea, A.; Massuti, C.; Pomar, L.; Acosta, J.; Herranz, P.; Sanz, J.L.

    1989-03-01

    Existing models for carbonate sedimentation on continental platforms are derived from the study of modern carbonate platforms in tropical climates. The Balearic platform in the western Mediterranean provides a new model for carbonate sedimentation in a temperature, semiarid climate. On most of the continental shelf around the Balearic Islands, modern sediments are exclusively bioclastic carbonates. Shoreline carbonate sediments are bioclastic sands and muds accumulating in beach-dune systems without significant tidal influence (there are no astronomical tides in the western Mediterranean ). From the upper shoreface to 35 m deep, the sandy bottom is extensively colonized by sea grass (Posidonia oceanica), the rhizomes and roots of which form a rigid entrapment that retains the sediment derived from calcareous organisms living within the sea grass and from calcareous epiphytes living on the stems and leaves. Archeological dating establishes a rate of vertical accretion in this zone of 10/sup 3/ Bubnoff units (1 Bubnoff unit = 1 mm/1000 years). Between depths of 40 and 60 m, carbonate sands are composed predominantly or red-algal fragments. Intensely bioturbated wave ripples occur in environments dominated by laminar red algae (Lithothamnium and Phymatolithon). Below depths of 60 m, coarse sediment produced by rhodolitic and ramose red algae is deposited in areas of tens to hundreds of meters in size. Biogenic buildups up to 2 m high occur in sandy areas as well as in deeper muddy areas. At the same depth in open-platform zones, the bottom topography is characterized by large hummocks several hundred meters across. From the horizontal distribution of facies, it is possible to construct the probable vertical sequence of lithofacies which would characterize carbonates accumulating on a temperate-climate carbonate shelf. Many of these lithofacies are recognized in upper Miocene limestones on the Balearic Islands.

  13. Climate change and the increasing impact of polar bears on bird populations

    Directory of Open Access Journals (Sweden)

    Jouke eProp

    2015-03-01

    Full Text Available The Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard and one in east Greenland. Summer occurrence of polar bears, measured as the probability of encountering bears and the number of days with bear presence, has increased significantly from the 1970/80s to the present. The shifts in polar bear occurrence coincided with trends for shorter sea ice seasons and less sea ice during the spring in the study area. This resulted in a strong inverse relationship between the probability of bear encounters on land and the length of the sea ice season. Within ten years after their first appearance on land, polar bears had advanced their arrival dates by almost 30 days. Direct observations of nest predation showed that polar bears may severely affect reproductive success of the barnacle goose (Branta leucopsis, common eider (Somateria mollissima and glaucous gull (Larus hyperboreus. Nest predation was strongest in years when the polar bears arrived well before hatch, with more than 90% of all nests being predated. The results are similar to findings from Canada, and large-scale processes, such as climate and subsequent habitat changes, are pinpointed as the most likely drivers in various parts of the Arctic. We suggest that the increasing, earlier appearance of bears on land in summer reflects behavioral adaptations by a small segment of the population to cope with a reduced hunting range on sea ice. This exemplifies how behavioral adaptations may contribute to the cascading effects of climate change.

  14. Establishment of primary cell culture from the temperate symbiotic cnidarian, Anemonia viridis.

    Science.gov (United States)

    Barnay-Verdier, Stéphanie; Dall'osso, Diane; Joli, Nathalie; Olivré, Juliette; Priouzeau, Fabrice; Zamoum, Thamilla; Merle, Pierre-Laurent; Furla, Paola

    2013-10-01

    The temperate symbiotic sea anemone Anemonia viridis, a member of the Cnidaria phylum, is a relevant experimental model to investigate the molecular and cellular events involved in the preservation or in the rupture of the symbiosis between the animal cells and their symbiotic microalgae, commonly named zooxanthellae. In order to increase research tools for this model, we developed a primary culture from A. viridis animal cells. By adapting enzymatic dissociation protocols, we isolated animal host cells from a whole tentacle in regeneration state. Each plating resulted in a heterogeneous primary culture consisted of free zooxanthellae and many regular, small rounded and adherent cells (of 3-5 μm diameter). Molecular analyses conducted on primary cultures, maintained for 2 weeks, confirmed a specific signature of A. viridis cells. Further serial dilutions and micromanipulation allowed us to obtain homogenous primary cultures of the small rounded cells, corresponding to A. viridis "epithelial-like cells". The maintenance and the propagation over a 4 weeks period of primary cells provide, for in vitro cnidarian studies, a preliminary step for further investigations on cnidarian cellular pathways notably in regard to symbiosis interactions.

  15. Tropical-temperate interactions over southern Africa simulated by a regional climate model

    Energy Technology Data Exchange (ETDEWEB)

    Vigaud, N.; Pohl, B.; Cretat, J. [UMR 6282 Biogeosciences CNRS/Universite de Bourgogne, Centre de Recherches de Climatologie, Dijon (France)

    2012-12-15

    The Weather Research and Forecasting model (WRF) forced by ERA40 re-analyses, is used to examine, at regional scale, the role of key features of the local atmospheric circulation on the origin and development of Tropical Temperate Troughs (TTTs) representing a major contribution to South African rainfall during austral summer. A cluster analysis applied on 1971-2000 ERA40 and WRF simulated daily outgoing longwave radiation reveals for the November-February season three coherent regimes characteristic of TTTs over the region. Analyses of WRF simulated TTTs suggest that their occurrence is primarily linked with mid-latitude westerly waves and their phasing. Ensemble experiments designed for the case of austral summer 1996/1997 allow to examine the reproducibility of TTT events. The results obtained illustrate the importance of westerly waves phasing regarding the persistence of rain-producing continental TTT events. Moreover, oceanic surface conditions prevailing over the Agulhas current regions of the South West Indian Ocean (SWIO) are also found to influence TTT persistence for regional experiments with an oceanic mixed layer, warmer sea surface temperatures being associated with increased moisture advection from the SWIO where latent heat release is enhanced, favoring baroclinic instability and thus sustaining convection activity locally. (orig.)

  16. Emergent Toxins in North Atlantic Temperate Waters: A Challenge for Monitoring Programs and Legislation

    Directory of Open Access Journals (Sweden)

    Marisa Silva

    2015-03-01

    Full Text Available Harmful Algal Blooms (HAB are complex to manage due to their intermittent nature and their severe impact on the economy and human health. The conditions which promote HAB have not yet been fully explained, though climate change and anthropogenic intervention are pointed as significant factors. The rise of water temperature, the opening of new sea canals and the introduction of ship ballast waters all contribute to the dispersion and establishment of toxin-producing invasive species that promote the settling of emergent toxins in the food-chain. Tetrodotoxin, ciguatoxin, palytoxin and cyclic imines are commonly reported in warm waters but have also caused poisoning incidents in temperate zones. There is evidence that monitoring for these toxins exclusively in bivalves is simplistic and underestimates the risk to public health, since new vectors have been reported for these toxins and as well for regulated toxins such as PSTs and DSTs. In order to avoid public health impacts, there is a need for adequate monitoring programs, a need for establishing appropriate legislation, and a need for optimizing effective methods of analysis. In this review, we will compile evidence concerning emergent marine toxins and provide data that may indicate the need to restructure the current monitoring programs of HAB.

  17. Emergent toxins in North Atlantic temperate waters: a challenge for monitoring programs and legislation.

    Science.gov (United States)

    Silva, Marisa; Pratheepa, Vijaya K; Botana, Luis M; Vasconcelos, Vitor

    2015-03-16

    Harmful Algal Blooms (HAB) are complex to manage due to their intermittent nature and their severe impact on the economy and human health. The conditions which promote HAB have not yet been fully explained, though climate change and anthropogenic intervention are pointed as significant factors. The rise of water temperature, the opening of new sea canals and the introduction of ship ballast waters all contribute to the dispersion and establishment of toxin-producing invasive species that promote the settling of emergent toxins in the food-chain. Tetrodotoxin, ciguatoxin, palytoxin and cyclic imines are commonly reported in warm waters but have also caused poisoning incidents in temperate zones. There is evidence that monitoring for these toxins exclusively in bivalves is simplistic and underestimates the risk to public health, since new vectors have been reported for these toxins and as well for regulated toxins such as PSTs and DSTs. In order to avoid public health impacts, there is a need for adequate monitoring programs, a need for establishing appropriate legislation, and a need for optimizing effective methods of analysis. In this review, we will compile evidence concerning emergent marine toxins and provide data that may indicate the need to restructure the current monitoring programs of HAB.

  18. Polar bear attacks on humans: Implications of a changing climate

    Science.gov (United States)

    Wilder, James; Vongraven, Dag; Atwood, Todd C.; Hansen, Bob; Jessen, Amalie; Kochnev, Anatoly A.; York, Geoff; Vallender, Rachel; Hedman, Daryll; Gibbons, Melissa

    2017-01-01

    Understanding causes of polar bear (Ursus maritimus) attacks on humans is critical to ensuring both human safety and polar bear conservation. Although considerable attention has been focused on understanding black (U. americanus) and grizzly (U. arctos) bear conflicts with humans, there have been few attempts to systematically collect, analyze, and interpret available information on human-polar bear conflicts across their range. To help fill this knowledge gap, a database was developed (Polar Bear-Human Information Management System [PBHIMS]) to facilitate the range-wide collection and analysis of human-polar bear conflict data. We populated the PBHIMS with data collected throughout the polar bear range, analyzed polar bear attacks on people, and found that reported attacks have been extremely rare. From 1870–2014, we documented 73 attacks by wild polar bears, distributed among the 5 polar bear Range States (Canada, Greenland, Norway, Russia, and United States), which resulted in 20 human fatalities and 63 human injuries. We found that nutritionally stressed adult male polar bears were the most likely to pose threats to human safety. Attacks by adult females were rare, and most were attributed to defense of cubs. We judged that bears acted as a predator in most attacks, and that nearly all attacks involved ≤2 people. Increased concern for both human and bear safety is warranted in light of predictions of increased numbers of nutritionally stressed bears spending longer amounts of time on land near people because of the loss of their sea ice habitat. Improved conflict investigation is needed to collect accurate and relevant data and communicate accurate bear safety messages and mitigation strategies to the public. With better information, people can take proactive measures in polar bear habitat to ensure their safety and prevent conflicts with polar bears. This work represents an important first step towards improving our understanding of factors influencing

  19. Acquiring negative polarity items

    NARCIS (Netherlands)

    Lin, J.

    2015-01-01

    Negative Polarity Items (NPIs) are words or expressions that exhibit a restricted distribution to certain negative contexts only. For example, yet is an NPI and must appear in the scope of a negation: Mary has *(not) finished yet. The existence of NPIs such as yet gives rise to a learnability

  20. Polarized structure functions

    NARCIS (Netherlands)

    Mulders, P.J.G.

    2005-01-01

    We discuss the spin structure of quarks in hadrons, in particular the transverse spin polarization or transversity. The most direct way to probe transversity appears to be via azimuthal spin asymmetries. This brings in the role of intrinsic transverse momenta of quarks in hadrons and the study of

  1. Political Competition and Polarization

    DEFF Research Database (Denmark)

    Schultz, Christian

    This paper considers political competition and the consequences of political polarization when parties are better informed about how the economy functions than voters are. Specifically, parties know the cost producing a public good, voters do not. An incumbent's choice of policy acts like a signal...

  2. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  3. Acquisition of Oocyte Polarity.

    Science.gov (United States)

    Clapp, Mara; Marlow, Florence L

    2017-01-01

    Acquisition of oocyte polarity involves complex translocation and aggregation of intracellular organelles, RNAs, and proteins, along with strict posttranscriptional regulation. While much is still unknown regarding the formation of the animal-vegetal axis, an early marker of polarity, animal models have contributed to our understanding of these early processes controlling normal oogenesis and embryo development. In recent years, it has become clear that proteins with self-assembling properties are involved in assembling discrete subcellular compartments or domains underlying subcellular asymmetries in the early mitotic and meiotic cells of the female germline. These include asymmetries in duplication of the centrioles and formation of centrosomes and assembly of the organelle and RNA-rich Balbiani body, which plays a critical role in oocyte polarity. Notably, at specific stages of germline development, these transient structures in oocytes are temporally coincident and align with asymmetries in the position and arrangement of nuclear components, such as the nuclear pore and the chromosomal bouquet and the centrioles and cytoskeleton in the cytoplasm. Formation of these critical, transient structures and arrangements involves microtubule pathways, intrinsically disordered proteins (proteins with domains that tend to be fluid or lack a rigid ordered three-dimensional structure ranging from random coils, globular domains, to completely unstructured proteins), and translational repressors and activators. This review aims to examine recent literature and key players in oocyte polarity.

  4. No More Polarization, Please!

    DEFF Research Database (Denmark)

    Hansen, Mia Reinholt

    and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on motivation, acknowledging the co-existence of intrinsic and extrinsic motivation, the possible interaction...

  5. Highly transparent twist polarizer metasurface

    Science.gov (United States)

    Faniayeu, Ihar; Khakhomov, Sergei; Semchenko, Igor; Mizeikis, Vygantas

    2017-09-01

    A twist polarizer metasurface for polarization rotation by an angle of 90 ° is proposed and realized at microwave frequencies. The metasurface consists of sub-wavelength metallic helices arranged periodically in a single layer and operates in transmission geometry with a nearly unity cross-polarization conversion coefficient at resonance. The structure exhibits low reflectivity R polarization orientation of the incident wave. Moreover, it can operate with high efficiency at oblique incidence angles of up to 35 ° . Such twist polarizer metasurfaces are potentially applicable as electromagnetic/optical isolators and frequency-selective polarization antennas.

  6. Sea Ice Charts of the Russian Arctic in Gridded Format, 1933-2006, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia, produces sea ice charts for safety of navigation in the polar regions and for other...

  7. Sea Ice Charts of the Russian Arctic in Gridded Format, 1933-2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia, produces sea ice charts for safety of navigation in the polar regions and for other...

  8. Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

    Science.gov (United States)

    Hunt, George L.; Drinkwater, Kenneth F.; Arrigo, Kevin; Berge, Jørgen; Daly, Kendra L.; Danielson, Seth; Daase, Malin; Hop, Haakon; Isla, Enrique; Karnovsky, Nina; Laidre, Kristin; Mueter, Franz J.; Murphy, Eugene J.; Renaud, Paul E.; Smith, Walker O.; Trathan, Philip; Turner, John; Wolf-Gladrow, Dieter

    2016-12-01

    We compare and contrast the ecological impacts of atmospheric and oceanic circulation patterns on polar and sub-polar marine ecosystems. Circulation patterns differ strikingly between the north and south. Meridional circulation in the north provides connections between the sub-Arctic and Arctic despite the presence of encircling continental landmasses, whereas annular circulation patterns in the south tend to isolate Antarctic surface waters from those in the north. These differences influence fundamental aspects of the polar ecosystems from the amount, thickness and duration of sea ice, to the types of organisms, and the ecology of zooplankton, fish, seabirds and marine mammals. Meridional flows in both the North Pacific and the North Atlantic oceans transport heat, nutrients, and plankton northward into the Chukchi Sea, the Barents Sea, and the seas off the west coast of Greenland. In the North Atlantic, the advected heat warms the waters of the southern Barents Sea and, with advected nutrients and plankton, supports immense biomasses of fish, seabirds and marine mammals. On the Pacific side of the Arctic, cold waters flowing northward across the northern Bering and Chukchi seas during winter and spring limit the ability of boreal fish species to take advantage of high seasonal production there. Southward flow of cold Arctic waters into sub-Arctic regions of the North Atlantic occurs mainly through Fram Strait with less through the Barents Sea and the Canadian Archipelago. In the Pacific, the transport of Arctic waters and plankton southward through Bering Strait is minimal. In the Southern Ocean, the Antarctic Circumpolar Current and its associated fronts are barriers to the southward dispersal of plankton and pelagic fishes from sub-Antarctic waters, with the consequent evolution of Antarctic zooplankton and fish species largely occurring in isolation from those to the north. The Antarctic Circumpolar Current also disperses biota throughout the Southern Ocean

  9. Polarization-Based Radar Detection in Sea Clutter

    Science.gov (United States)

    2015-02-27

    of incidence: ^ t + kdh/dXp [1 + idh /dXaYV/^ e is in the direction of the E-field in the transverse plane, Ho is the outer surface normal...and with — idh /dXo + k "° " [1 + (d/i/aXo)2]i/2 _ e^ cos 9{ — ^erUr — sin^ 9{ cos Of = -rio • kinc sin df = t- ki (83) e^ cos df - yJerHr

  10. High resolution modelling of the decreasing Arctic sea ice

    DEFF Research Database (Denmark)

    Madsen, K. S.; Rasmussen, T. A. S.; Blüthgen, Jonas

    2012-01-01

    , and secondly oceanic oil drift in ice affected conditions. Both investigations are made with the coupled ocean - sea ice model HYCOM-CICE at 10 km resolution, which is also used operationally at DMI and allows detailed studies of sea ice build-up, drift and melt. To investigate the sea ice decrease of the last......The Arctic sea ice cover has been rapidly decreasing and thinning over the last decade, with minimum ice extent in 2007 and almost as low extent in 2011. This study investigates two aspects of the decreasing ice cover; first the large scale thinning and changing dynamics of the polar sea ice...... decade, we have performed a reanalysis simulation of the years 1990-2011, forced with ERA Interim atmospheric data. Thus, the simulation includes both the period before the recent sea ice decrease and the full period of decrease up till today. We will present our model results of the thinning...

  11. Soil phosphorus fractionation as a tool for monitoring dust phosphorus signature underneath a Blue Pine (Pinus wallichiana) canopy in a Temperate Forest

    Energy Technology Data Exchange (ETDEWEB)

    Shafqat, M.N.; Shahid, S.; Eqani, S.A.M.A.S.; Shah, S.H.; Waseem, A.

    2016-07-01

    Aim of the study: This study aims (i) to monitor the amount of dust deposition during dry season in the moist temperate forest; (ii) to study nature of P fractions in the dust samples falling on the trees in the region; (iii) to study soil P fractions as influenced by the processes of throughfall and stemflow of a Blue Pine (Pinus wallichiana) canopy and to finger print the contribution of dust towards P input in the temperate forest ecosystem. Area of study: The site used for the collection of soil samples was situated at an elevation of 6900 feet above sea levels (temperate forest in Himalaya region) in the Thandani area national forest located in the north west of Pakistan. Material and methods: For soil sampling and processing, three forest sites with three old tree plants per site were selected at approximately leveled plain for surface soil sampling. Two dust samples were collected and analyzed for different physicochemical properties along with different P fractions. First dust sample was collected from a site situated at an elevation of 4000 feet and second one was collected from an elevation of 6500 feet above sea levels. Modified Hedley procedure for the fractionation of P in the dust and soil samples were used. Main results: The input of dust was 43 and 20 kg ha-1 during drier months of the year (September-June) at lower and higher elevation sites respectively, and the dust from lower elevation site had relative more all P fractions than the other dust sample. However, HCl-Pi fraction was dominant in both samples. Both labile (water plus NaHCO3) and non-labile (NaOH plus HCl) inorganic P (Pi) fractions were significantly increased in the surface soil by both stemflow and throughfall compared to the open field soil. The buildup of NaOH and HCl-Pi pools in soils underneath the canopy might prove useful in fingerprinting the contribution of atmospheric dust towards P cycling in this temperate forest. Research highlights: The role of dust in the cycling of P

  12. Mammals of the Sea.

    Science.gov (United States)

    Naturescope, 1986

    1986-01-01

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

  13. $\\mu$-tempered metadynamics: Artifact independent convergence times for wide hills

    CERN Document Server

    Dickson, Bradley M

    2015-01-01

    Recent analysis of well-tempered metadynamics (WTmetaD) showed that it converges without mollification artifacts in the bias potential. Here we explore how metadynamics heals mollification artifacts, how healing impacts convergence time, and whether alternative temperings may be used to improve efficiency. We introduce "$\\mu$-tempered" metadynamics as a simple tempering scheme, inspired by a related mollified adaptive biasing potential (mABP), that results in artifact independent convergence of the free energy estimate. We use a toy model to examine the role of artifacts in WTmetaD and solvated alanine dipeptide to compare the well-tempered and $\\mu$-tempered frameworks demonstrating fast convergence for hill widths as large as $60^{\\circ}$ for $\\mu$TmetaD.

  14. Dilatometric and hardness analysis of C45 steel tempering with different heating-up rates

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2012-01-01

    Full Text Available Modelling of technological processes of heat treatment or welding, involving multiple heat source transitions, requires considering the phenomenon of tempering. In work have been presented results of dilatometric research of hardened C45 steel subjected to tempering. The analysis of the influence of heating rate at the kinetic determined from dilatometric curves has been made. There have also been estimated quantities of transformation expansions and thermal expansion coefficients of hardening and tempering structures (austenite, ferrite, pearlite, martensite and sorbite. The analysis of tempering time influence on the hardness of tempered steel has been made. Functions associating hardness with tempering time (rate of heating-up in technological processes based on short-timed action of a heat source (eg. laser treatment have been suggested.

  15. Enhanced polarization by the coherent heterophase interface between polar and non-polar phases.

    Science.gov (United States)

    Kim, Gi-Yeop; Sung, Kil-Dong; Rhyim, Youngmok; Yoon, Seog-Young; Kim, Min-Soo; Jeong, Soon-Jong; Kim, Kwang-Ho; Ryu, Jungho; Kim, Sung-Dae; Choi, Si-Young

    2016-04-14

    A piezoelectric composite containing the ferroelectric polar (Bi(Na0.8K0.2)0.5TiO3: f-BNKT) and the non-polar (0.94Bi(Na0.75K0.25)0.5TiO3-0.06BiAlO3: BNKT-BA) phases exhibits synergetic properties which combine the beneficial aspects of each phase, i.e., the high saturated polarization (Ps) of the polar phase and the low coercive field (Ec) of the non-polar phase. To understand the origin of such a fruitful outcome from this type of polar/non-polar heterophase structure, comprehensive studies are conducted, including transmission electron microscopy (TEM) and finite element method (FEM) analyses. The TEM results show that the polar/non-polar composite has a core/shell structure in which the polar phase (core) is surrounded by a non-polar phase (shell). In situ electrical biasing TEM experiments visualize that the ferroelectric domains in the polar core are aligned even under an electric field of ∼1 kV mm(-1), which is much lower than its intrinsic coercive field (∼3 kV mm(-1)). From the FEM analyses, we can find that the enhanced polarization of the polar phase is promoted by an additional internal field at the phase boundary which originates from the preferential polarization of the relaxor-like non-polar phase. From the present study, we conclude that the coherent interface between polar and non-polar phases is a key factor for understanding the enhanced piezoelectric properties of the composite.

  16. Habitat degradation affects the summer activity of polar bears

    Science.gov (United States)

    Ware, Jasmine V.; Rode, Karyn D.; Bromaghin, Jeffrey F.; Douglas, David C.; Wilson, Ryan R.; Regehr, Eric V.; Amstrup, Steven C.; Durner, George M.; Pagano, Anthony M.; Olson, Jay; Robbins, Charles T.; Jansen, Heiko T

    2017-01-01

    Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species’ distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50–75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.

  17. Habitat degradation affects the summer activity of polar bears.

    Science.gov (United States)

    Ware, Jasmine V; Rode, Karyn D; Bromaghin, Jeffrey F; Douglas, David C; Wilson, Ryan R; Regehr, Eric V; Amstrup, Steven C; Durner, George M; Pagano, Anthony M; Olson, Jay; Robbins, Charles T; Jansen, Heiko T

    2017-05-01

    Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.

  18. NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6

    NARCIS (Netherlands)

    SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM

    1993-01-01

    Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,

  19. Sea ice contribution to the air-sea CO(2) exchange in the Arctic and Southern Oceans

    DEFF Research Database (Denmark)

    Rysgaard...[], Søren; Bendtsen, Jørgen; Delille, B.

    2011-01-01

    Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO(2) and the subsequent effect on air-sea CO(2) exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air......-sea CO(2) exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO(2) uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO(2) uptake in ice-free polar seas. This sea......-ice driven CO(2) uptake has not been considered so far in estimates of global oceanic CO(2) uptake. Net CO(2) uptake in sea-ice-covered oceans can be driven by; (1) rejection during sea-ice formation and sinking of CO(2)-rich brine into intermediate and abyssal oceanic water masses, (2) blocking of air...

  20. Geomagnetic polarity transitions

    Science.gov (United States)

    Merrill, Ronald T.; McFadden, Phillip L.

    1999-05-01

    The top of Earth's liquid outer core is nearly 2900 km beneath Earth's surface, so we will never be able to observe it directly. This hot, dense, molten iron-rich body is continuously in motion and is the source of Earth's magnetic field. One of the most dynamic manifestations at Earth's surface of this fluid body is, perhaps, a reversal of the geomagnetic field. Unfortunately, the most recent polarity transition occurred at about 780 ka, so we have never observed a transition directly. It seems that a polarity transition spans many human lifetimes, so no human will ever witness the phenomenon in its entirety. Thus we are left with the tantalizing prospect that paleomagnetic records of polarity transitions may betray some of the secrets of the deep Earth. Certainly, if there are systematics in the reversal process and they can be documented, then this will reveal substantial information about the nature of the lowermost mantle and of the outer core. Despite their slowness on a human timescale, polarity transitions occur almost instantaneously on a geological timescale. This rapidity, together with limitations in the paleomagnetic recording process, prohibits a comprehensive description of any reversal transition both now and into the foreseeable future, which limits the questions that may at this stage be sensibly asked. The natural model for the geomagnetic field is a set of spherical harmonic components, and we are not able to obtain a reliable model for even the first few harmonic terms during a transition. Nevertheless, it is possible, in principle, to make statements about the harmonic character of a geomagnetic polarity transition without having a rigorous spherical harmonic description of one. For example, harmonic descriptions of recent geomagnetic polarity transitions that are purely zonal can be ruled out (a zonal harmonic does not change along a line of latitude). Gleaning information about transitions has proven to be difficult, but it does seem