Now showing items 741-760 of 1012

    • Supraglacial ponds regulate runoff from Himalayan debris-covered glaciers 

      Irvine-Fynn, Tristram D.L.; Porter, Philip R.; Rowan, Ann V.; Quincey, Duncan J.; Gibson, Morgan J.; Bridge, Jonathan W.; Watson, C. Scott; Hubbard, Alun Lloyd; Glasser, Neil F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-29)
      Meltwater and runoff from glaciers in High Mountain Asia is a vital freshwater resource for one-fifth of the Earth’s population. Between 13% and 36% of the region’s glacierized areas exhibit surface debris cover and associated supraglacial ponds whose hydrological buffering roles remain unconstrained. We present a high-resolution meltwater hydrograph from the extensively debris-covered Khumbu ...
    • Benthic foraminifera as bio-indicators of chemical and physical stressors in Hammerfest harbor (Northern Norway) 

      Dijkstra, Noortje; Junttila, Juho; Skirbekk, Kari; Carroll, JoLynn; Husum, Katrine; Hald, Morten (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-10-01)
      We investigated benthic foraminiferal assemblages in contaminated sediments in a subarctic harbor of northern Norway to assess their utility as indicators of anthropogenic impacts. Sediments in the harbor are repositories for POPs and heavy metals supplied through discharges from industry and shipping activities. Sediment contaminant concentrations are at moderate to poor ecological quality ...
    • Environmental baselines and reconstruction of Atlantic Water inflow in Bjørnøyrenna, SW Barents Sea, since 1800 CE 

      Dijkstra, Noortje; Junttila, Juho; Sørensen, Steffen Aagaard (Journal article; Tidsskriftartikkel, 2017-10-28)
      Metal concentrations, sediment properties and benthic foraminiferal assemblages were investigated in sediment cores in the SW Barents Sea, to reconstruct environmental baselines and natural variability of Atlantic Water inflow since 1800 CE. Metal concentrations correspond to no effect levels and do not influence the foraminifera. Increased Hg and Pb was linked to inflow of Atlantic Water. The data ...
    • Eurasian ice-sheet dynamics and sensitivity to subglacial hydrology 

      Gudlaugsson, Eythor; Humbert, Angelika; Andreassen, Karin; Clason, Caroline C.; Kleiner, Thomas; Beyer, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-24)
      Ice-stream dynamics are strongly controlled by processes taking place at the ice/bed interface where subglacial water both lubricates the base and saturates any existing, underlying sediment. Large parts of the former Eurasian ice sheet were underlain by thick sequences of soft, marine sediments and many areas are imprinted with geomorphological features indicative of fast flow and wet basal conditions. ...
    • Assessment of offshore wind power potential in the Aegean and Ionian<br> Seas based on high-resolution hindcast model results 

      Soukissian, Takvor; Papadopoulos, Anastasios; Skrimizeas, Panagiotis; Karathanasi, Flora; Axaopoulos, Panagiotis; Avgoustoglou, Evripides; Kyriakidou, Hara; Tsalis, Christos; Voudouri, Antigoni; Gofa, Flora; Katsafados, Petros (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-20)
      In this study long-term wind data obtained from high-resolution hindcast simulations is used to analytically assess offshore wind power potential in the Aegean and Ionian Seas and provide wind climate and wind power potential characteristics at selected locations, where offshore wind farms are at the concept/planning phase. After ensuring the good model performance through detailed validation against ...
    • Possible climate preconditioning on submarine landslides along a convergent margin, Nankai Trough (NE Pacific) 

      Kremer, Katrina; Usman, Muhammed; Satoguchi, Yasufumi; Nagahashi, Yoshitaka; Vadakkepuliyambatta, Sunil; Panieri, Giuliana; Strasser, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-25)
      Submarine landslides are major agents of sediment mass transfer from the shallow to deep sea. Due to their rapid emplacement and tsunamigenic potential, such landslides are significant geohazards for society and off- and on-shore infrastructure. The relationship between climate change and the occurrence of submarine landslides is widely debated. However, there is a lack of continuous long-term ...
    • Methane- and dissolved organic carbon-fueled microbial loop supports a tropical subterranean estuary ecosystem 

      Brankovits, D.; Pohlman, J.W.; Niemann, Helge; Leigh, M.B.; Leewis, M.C.; Becker, K.W.; Iliffe, F.A.; Lehmann, M.F.; Phillips, B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-28)
      Subterranean estuaries extend inland into density-stratified coastal carbonate aquifers containing a surprising diversity of endemic animals (mostly crustaceans) within a highly oligotrophic habitat. How complex ecosystems (termed anchialine) thrive in this globally distributed, cryptic environment is poorly understood. Here, we demonstrate that a microbial loop shuttles methane and dissolved organic ...
    • Derivation of High Spatial Resolution Albedo from UAV Digital Imagery: Application over the Greenland Ice Sheet 

      Ryan, Jonathan C.; Hubbard, Alun Lloyd; Box, Jason E.; Brough, Stephen; Cameron, Karen; Cook, Joseph M.; Cooper, Matthew; Doyle, Samuel H.; Edwards, Arwyn; Holt, Tom; Irvine-Fynn, Tristram; Jones, Christine; Pitcher, Lincoln H.; Rennermalm, Åsa K.; Smith, Laurence C.; Stibal, Marek; Snooke, Neal (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-23)
      Measurements of albedo are a prerequisite for modeling surface melt across the Earth’s cryosphere, yet available satellite products are limited in spatial and/or temporal resolution. Here, we present a practical methodology to obtain centimeter resolution albedo products with accuracies of ±5% using consumer-grade digital camera and unmanned aerial vehicle (UAV) technologies. Our method comprises ...
    • Sedimentology of the Lower Cretaceous at Kikutodden and Keilhaufjellet, southern Spitsbergen: implications for an onshore-offshore link 

      Grundvåg, Sten-Andreas; Olaussen, Snorre (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-10)
      Detailed sedimentological investigations of the Lower Cretaceous succession of southernmost Spitsbergen indicate deposition during a long-term fall and rise in relative sea level. The Rurikfjellet Formation shows an overall regressive development and consists of offshore deposits grading upwards into progradationally stacked shoreface parasequences. The overlying Helvetiafjellet Formation shows a ...
    • Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period 

      Klages, Johann Philipp; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Smith, James; Graham, Alastair G C; Nitsche, F. O.; Frederichs, Thomas; Jernas, Patrycja Ewa; Gohl, Karsten; Wacker, Lukas (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-25)
      Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5–19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions ...
    • Surface water conditions and calcium carbonate preservation in the Fram Strait during marine isotope stage 2, 28.8–15.4 kyr 

      Zamelczyk, Katarzyna; Rasmussen, Tine Lander; Husum, Katrine; Godtliebsen, Fred; Hald, Morten (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-01-14)
      We present a high-resolution record of calcium carbonate preservation alongside the distribution pattern of planktic foraminifera from the Fram Strait. The record covers the marine isotope stage (MIS) 2, 28.8 to 15.4 kyr, including the Last Glacial Maximum (LGM) and the early deglaciation in multidecadal temporal resolution. The investigation is based on the distribution patterns of planktic ...
    • Visualizing tephra deposits and sedimentary processes in the marine environment: The potential of X-ray microtomography 

      Griggs, Adam J.; Davies, Siwan M.; Abbott, Peter M.; Coleman, Mark; Palmer, Adrian P.; Rasmussen, Tine Lander; Johnston, Richard (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-30)
      Localized tephra deposition in marine sequences is the product of many complex primary and secondary depositional processes. These can significantl y influence the potential applicability of tephra depos- its as isochronous marker horizons and current techniques, used in isolation, may be insufficient to fully unravel these processes. Here we demonstrate the innovative application of X-ray ...
    • Water mass exchange between the Nordic Seas and the Arctic Ocean on millennial time scale during MIS 4–2 

      Rasmussen, Tine Lander; Thomsen, Erik; Nielsen, Tove (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      The climate of the last glaciation circa 65,000–25,000 years ago was interrupted by about 15 abrupt temperature fluctuations, the so-called Dansgaard-Oeschger events consisting of warm interstadials and cold stadials recorded in Greenland ice cores. The largest fluctuations occur in the North Atlantic region, but they have been registered over the most of the world. The events are linked to changes ...
    • Pink marine sediments reveal rapid ice melt and Arctic meltwater discharge during Dansgaard-Oeschger warmings 

      Rasmussen, Tine Lander; Thomsen, Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-11-22)
      The climate of the last glaciation was interrupted by numerous abrupt temperature fluctuations, referred to as Greenland interstadials and stadials. During warm interstadials the meridional overturning circulation was active transferring heat to the north, whereas during cold stadials the Nordic Seas were ice-covered and the overturning circulation was disrupted. Meltwater discharge, from ice sheets ...
    • Brine formation in relation to climate changes and ice retreat during the last 15,000 years in Storfjorden, Svalbard, 76–78°N 

      Rasmussen, Tine Lander; Thomsen, Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-10-06)
      Storfjorden, Svalbard, is an area of intense brine formation. The brine is cold, dense, rich in oxygen and CO2, and has reduced pH. Storfjorden is unique because it contains well-preserved agglutinated foraminifera dating back to the beginning of the last deglaciation. We have investigated the distribution of calcareous and agglutinated benthic foraminifera, benthic oxygen and carbon isotopes, ...
    • Cold-seep ostracods from the western Svalbard margin: direct palaeo-indicator for methane seepage? 

      Yasuhara, Moriaki; Sztybor, Kamila; Rasmussen, Tine Lander; Okahashi, Hisayo; Sato, Runa; Tanaka, Hayato (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-05)
      Despite their high abundance and diversity, microfossil taxa adapted to a particular chemosynthetic environment have rarely been studied and are therefore poorly known. Here we report on an ostracod species, Rosaliella svalbardensis gen. et sp. nov., from a cold methane seep site at the western Svalbard margin, Fram Strait. The new species shows a distinct morphology, different from other ...
    • Visualizing and interpreting surface displacement patterns on unstable slopes using multi-geometry satellite SAR interferometry (2D InSAR) 

      Eriksen, Harald Øverli; Lauknes, Tom Rune; Larsen, Yngvar; Corner, Geoffrey D.; Bergh, Steffen G; Dehls, John; Kierulf, Halfdan Pascal (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-05)
      It is well known that satellite radar interferometry (InSAR) is capable of measuring surface displacement with a typical accuracy on the order of millimeters to centimeters. However, when the true deformation vector differs from the satellite line-of-sight (LOS), the sensitivity decreases and interpretation of InSAR deformationmeasurements becomes challenging. By combining displacement data ...
    • Evaluering av automatiske snøskredvarslingsanlegg 

      Lome, Kristin Brandtsegg (Master thesis; Mastergradsoppgave, 2017-12-01)
      Noen veger blir stengt på ubestemt tid på grunn av snøskredfare. Dette er frustrerende for trafikanter og det skaper økonomiske konsekvenser for næringslivet. Statens vegvesen (SVV) har testet ut to teknologier for å detektere og varsle snøskred i sanntid; doppler radar og geofoner. Radaren bruker radiobølger for å måle retning og avstand til et objekt og kan dermed benyttes til å bestemme om skredet ...
    • Deglaciation of the Eurasian ice sheet complex 

      Patton, Henry; Hubbard, Alun Lloyd; Andreassen, Karin; Auriac, Amandine; Whitehouse, Pippa L.; Stroeven, Arjen P.; Shackleton, Calvin; Winsborrow, Monica; Heyman, Jakob; Hall, Adrian M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-14)
      The Eurasian ice sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum with a span of over 4500 km and responsible for around 20 m of eustatic sea-level lowering. Whilst recent terrestrial and marine empirical insights have improved understanding of the chronology, pattern and rates of retreat of this vast ice sheet, a concerted attempt to model the deglaciation of the ...
    • Correspondence: Reply to ‘Challenges with dating weathering products to unravel ancient landscapes’ 

      Fredin, Ola; Viola, Giulio; Zwingmann, Horst; Sørlie, Ronald; Brönner, Marco; Lie, Jan-Erik; Grandal, Else Margrethe; Müller, Axel; Margreth, Annina; Vogt, Christoph; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-15)
      As the title of the correspondence by Fossen et al. suggests, determining the age of landscape elements of the Earth surface is difficult. We thus welcome the opportunity to clarify our arguments on the contentious themes touched upon by Fredin et al.