Changes in the Configuration of Ice Stream Flow from the West Antarctic Ice Sheet
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Early Break-Up of the Norwegian Channel Ice Stream During the Last Glacial Maximum
Quaternary Science Reviews 107 (2015) 231e242 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Early break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum * John Inge Svendsen a, , Jason P. Briner b, Jan Mangerud a, Nicolas E. Young c a Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Postbox 7803, N-5020 Bergen, Norway b Department of Geology, University at Buffalo, Buffalo, NY 14260, USA c Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA article info abstract Article history: We present 18 new cosmogenic 10Be exposure ages that constrain the breakup time of the Norwegian Received 11 June 2014 Channel Ice Stream (NCIS) and the initial retreat of the Scandinavian Ice Sheet from the Southwest coast Received in revised form of Norway following the Last Glacial Maximum (LGM). Seven samples from glacially transported erratics 31 October 2014 on the island Utsira, located in the path of the NCIS about 400 km up-flow from the LGM ice front Accepted 3 November 2014 position, yielded an average 10Be age of 22.0 ± 2.0 ka. The distribution of the ages is skewed with the 4 Available online youngest all within the range 20.2e20.8 ka. We place most confidence on this cluster of ages to constrain the timing of ice sheet retreat as we suspect the 3 oldest ages have some inheritance from a previous ice Keywords: Norwegian Channel Ice Stream free period. Three additional ages from the adjacent island Karmøy provided an average age of ± 10 Scandinavian Ice Sheet 20.9 0.7 ka, further supporting the new timing of retreat for the NCIS. -
Ribbed Bedforms in Palaeo-Ice Streams Reveal Shear Margin
https://doi.org/10.5194/tc-2020-336 Preprint. Discussion started: 21 November 2020 c Author(s) 2020. CC BY 4.0 License. Ribbed bedforms in palaeo-ice streams reveal shear margin positions, lobe shutdown and the interaction of meltwater drainage and ice velocity patterns Jean Vérité1, Édouard Ravier1, Olivier Bourgeois2, Stéphane Pochat2, Thomas Lelandais1, Régis 5 Mourgues1, Christopher D. Clark3, Paul Bessin1, David Peigné1, Nigel Atkinson4 1 Laboratoire de Planétologie et Géodynamique, UMR 6112, CNRS, Le Mans Université, Avenue Olivier Messiaen, 72085 Le Mans CEDEX 9, France 2 Laboratoire de Planétologie et Géodynamique, UMR 6112, CNRS, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44322 Nantes CEDEX 3, France 10 3 Department of Geography, University of Sheffield, Sheffield, UK 4 Alberta Geological Survey, 4th Floor Twin Atria Building, 4999-98 Ave. Edmonton, AB, T6B 2X3, Canada Correspondence to: Jean Vérité ([email protected]) Abstract. Conceptual ice stream landsystems derived from geomorphological and sedimentological observations provide 15 constraints on ice-meltwater-till-bedrock interactions on palaeo-ice stream beds. Within these landsystems, the spatial distribution and formation processes of ribbed bedforms remain unclear. We explore the conditions under which these bedforms develop and their spatial organisation with (i) an experimental model that reproduces the dynamics of ice streams and subglacial landsystems and (ii) an analysis of the distribution of ribbed bedforms on selected examples of paleo-ice stream beds of the Laurentide Ice Sheet. We find that a specific kind of ribbed bedforms can develop subglacially 20 from a flat bed beneath shear margins (i.e., lateral ribbed bedforms) and lobes (i.e., submarginal ribbed bedforms) of ice streams. -
Rapid Transport of Ash and Sulfate from the 2011 Puyehue-Cordón
PUBLICATIONS Journal of Geophysical Research: Atmospheres RESEARCH ARTICLE Rapid transport of ash and sulfate from the 2011 10.1002/2017JD026893 Puyehue-Cordón Caulle (Chile) eruption Key Points: to West Antarctica • Ash and sulfate from the June 2011 Puyehue-Cordón Caulle eruption were Bess G. Koffman1,2 , Eleanor G. Dowd1 , Erich C. Osterberg1 , David G. Ferris1, deposited in West Antarctica 3 3 3,4 1 • Depositional phasing and duration Laura H. Hartman , Sarah D. Wheatley , Andrei V. Kurbatov , Gifford J. Wong , 5 6 3,4 4 suggest rapid transport through the Bradley R. Markle , Nelia W. Dunbar , Karl J. Kreutz , and Martin Yates troposphere • Ash/sulfate phasing, ash size 1Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA, 2Now at Department of Geology, Colby distributions, and geochemistry College, Waterville, Maine, USA, 3Climate Change Institute, University of Maine, Orono, Maine, USA, 4School of Earth and distinguish this midlatitude eruption Climate Sciences, University of Maine, Orono, Maine, USA, 5Department of Earth and Space Sciences, University of from low- and high-latitude eruptions Washington, Seattle, Washington, USA, 6New Mexico Bureau of Geology and Mineral Resources, Socorro, New Mexico, USA Supporting Information: • Supporting Information S1 Abstract The Volcanic Explosivity Index 5 eruption of the Puyehue-Cordón Caulle volcanic complex (PCC) in central Chile, which began 4 June 2011, provides a rare opportunity to assess the rapid transport and Correspondence to: deposition of sulfate and ash from a midlatitude volcano to the Antarctic ice sheet. We present sulfate, B. G. Koffman, [email protected] microparticle concentrations of fine-grained (~5 μm diameter) tephra, and major oxide geochemistry, which document the depositional sequence of volcanic products from the PCC eruption in West Antarctic snow and shallow firn. -
A Review of Ice-Sheet Dynamics in the Pine Island Glacier Basin, West Antarctica: Hypotheses of Instability Vs
Pine Island Glacier Review 5 July 1999 N:\PIGars-13.wp6 A review of ice-sheet dynamics in the Pine Island Glacier basin, West Antarctica: hypotheses of instability vs. observations of change. David G. Vaughan, Hugh F. J. Corr, Andrew M. Smith, Adrian Jenkins British Antarctic Survey, Natural Environment Research Council Charles R. Bentley, Mark D. Stenoien University of Wisconsin Stanley S. Jacobs Lamont-Doherty Earth Observatory of Columbia University Thomas B. Kellogg University of Maine Eric Rignot Jet Propulsion Laboratories, National Aeronautical and Space Administration Baerbel K. Lucchitta U.S. Geological Survey 1 Pine Island Glacier Review 5 July 1999 N:\PIGars-13.wp6 Abstract The Pine Island Glacier ice-drainage basin has often been cited as the part of the West Antarctic ice sheet most prone to substantial retreat on human time-scales. Here we review the literature and present new analyses showing that this ice-drainage basin is glaciologically unusual, in particular; due to high precipitation rates near the coast Pine Island Glacier basin has the second highest balance flux of any extant ice stream or glacier; tributary ice streams flow at intermediate velocities through the interior of the basin and have no clear onset regions; the tributaries coalesce to form Pine Island Glacier which has characteristics of outlet glaciers (e.g. high driving stress) and of ice streams (e.g. shear margins bordering slow-moving ice); the glacier flows across a complex grounding zone into an ice shelf coming into contact with warm Circumpolar Deep Water which fuels the highest basal melt-rates yet measured beneath an ice shelf; the ice front position may have retreated within the past few millennia but during the last few decades it appears to have shifted around a mean position. -
Ilulissat Icefjord
World Heritage Scanned Nomination File Name: 1149.pdf UNESCO Region: EUROPE AND NORTH AMERICA __________________________________________________________________________________________________ SITE NAME: Ilulissat Icefjord DATE OF INSCRIPTION: 7th July 2004 STATE PARTY: DENMARK CRITERIA: N (i) (iii) DECISION OF THE WORLD HERITAGE COMMITTEE: Excerpt from the Report of the 28th Session of the World Heritage Committee Criterion (i): The Ilulissat Icefjord is an outstanding example of a stage in the Earth’s history: the last ice age of the Quaternary Period. The ice-stream is one of the fastest (19m per day) and most active in the world. Its annual calving of over 35 cu. km of ice accounts for 10% of the production of all Greenland calf ice, more than any other glacier outside Antarctica. The glacier has been the object of scientific attention for 250 years and, along with its relative ease of accessibility, has significantly added to the understanding of ice-cap glaciology, climate change and related geomorphic processes. Criterion (iii): The combination of a huge ice sheet and a fast moving glacial ice-stream calving into a fjord covered by icebergs is a phenomenon only seen in Greenland and Antarctica. Ilulissat offers both scientists and visitors easy access for close view of the calving glacier front as it cascades down from the ice sheet and into the ice-choked fjord. The wild and highly scenic combination of rock, ice and sea, along with the dramatic sounds produced by the moving ice, combine to present a memorable natural spectacle. BRIEF DESCRIPTIONS Located on the west coast of Greenland, 250-km north of the Arctic Circle, Greenland’s Ilulissat Icefjord (40,240-ha) is the sea mouth of Sermeq Kujalleq, one of the few glaciers through which the Greenland ice cap reaches the sea. -
U.S. Advance Exchange of Operational Information, 2005-2006
Advance Exchange of Operational Information on Antarctic Activities for the 2005–2006 season United States Antarctic Program Office of Polar Programs National Science Foundation Advance Exchange of Operational Information on Antarctic Activities for 2005/2006 Season Country: UNITED STATES Date Submitted: October 2005 SECTION 1 SHIP OPERATIONS Commercial charter KRASIN Nov. 21, 2005 Depart Vladivostok, Russia Dec. 12-14, 2005 Port Call Lyttleton N.Z. Dec. 17 Arrive 60S Break channel and escort TERN and Tanker Feb. 5, 2006 Depart 60S in route to Vladivostok U.S. Coast Guard Breaker POLAR STAR The POLAR STAR will be in back-up support for icebreaking services if needed. M/V AMERICAN TERN Jan. 15-17, 2006 Port Call Lyttleton, NZ Jan. 24, 2006 Arrive Ice edge, McMurdo Sound Jan 25-Feb 1, 2006 At ice pier, McMurdo Sound Feb 2, 2006 Depart McMurdo Feb 13-15, 2006 Port Call Lyttleton, NZ T-5 Tanker, (One of five possible vessels. Specific name of vessel to be determined) Jan. 14, 2006 Arrive Ice Edge, McMurdo Sound Jan. 15-19, 2006 At Ice Pier, McMurdo. Re-fuel Station Jan. 19, 2006 Depart McMurdo R/V LAURENCE M. GOULD For detailed and updated schedule, log on to: http://www.polar.org/science/marine/sched_history/lmg/lmgsched.pdf R/V NATHANIEL B. PALMER For detailed and updated schedule, log on to: http://www.polar.org/science/marine/sched_history/nbp/nbpsched.pdf SECTION 2 AIR OPERATIONS Information on planned air operations (see attached sheets) SECTION 3 STATIONS a) New stations or refuges not previously notified: NONE b) Stations closed or refuges abandoned and not previously notified: NONE SECTION 4 LOGISTICS ACTIVITIES AFFECTING OTHER NATIONS a) McMurdo airstrip will be used by Italian and New Zealand C-130s and Italian Twin Otters b) McMurdo Heliport will be used by New Zealand and Italian helicopters c) Extensive air, sea and land logistic cooperative support with New Zealand d) Twin Otters to pass through Rothera (UK) upon arrival and departure from Antarctica e) Italian Twin Otter will likely pass through South Pole and McMurdo. -
Glacial Processes and Landforms-Transport and Deposition
Glacial Processes and Landforms—Transport and Deposition☆ John Menziesa and Martin Rossb, aDepartment of Earth Sciences, Brock University, St. Catharines, ON, Canada; bDepartment of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada © 2020 Elsevier Inc. All rights reserved. 1 Introduction 2 2 Towards deposition—Sediment transport 4 3 Sediment deposition 5 3.1 Landforms/bedforms directly attributable to active/passive ice activity 6 3.1.1 Drumlins 6 3.1.2 Flutes moraines and mega scale glacial lineations (MSGLs) 8 3.1.3 Ribbed (Rogen) moraines 10 3.1.4 Marginal moraines 11 3.2 Landforms/bedforms indirectly attributable to active/passive ice activity 12 3.2.1 Esker systems and meltwater corridors 12 3.2.2 Kames and kame terraces 15 3.2.3 Outwash fans and deltas 15 3.2.4 Till deltas/tongues and grounding lines 15 Future perspectives 16 References 16 Glossary De Geer moraine Named after Swedish geologist G.J. De Geer (1858–1943), these moraines are low amplitude ridges that developed subaqueously by a combination of sediment deposition and squeezing and pushing of sediment along the grounding-line of a water-terminating ice margin. They typically occur as a series of closely-spaced ridges presumably recording annual retreat-push cycles under limited sediment supply. Equifinality A term used to convey the fact that many landforms or bedforms, although of different origins and with differing sediment contents, may end up looking remarkably similar in the final form. Equilibrium line It is the altitude on an ice mass that marks the point below which all previous year’s snow has melted. -
2006 NSIDC Annual Report
National Snow and Ice Data Center World Data Center for Glaciology, Boulder Annual Report 2006 Supporting Cryospheric Research Since 1976 National Snow and Ice Data Center World Data Center for Glaciology, Boulder Annual Report 2006 Cover image captions (clockwise from upper left) During the IceTrek expedition, team members tow a sled with equipment to install on an Antarctic iceberg. (Courtesy Ted Scambos, NSIDC) This image shows the Beaufort Sea Polynya. A polynya, or area of persistent open water surrounded by ice, appeared during the summer 2006 Arctic sea ice melt season. The polynya is the dark area of open water; to the left is the coastline of Alaska, showing fall foliage color, and to the bottom right is the North Pole. This image is from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, which flies on the NASA Terra and Aqua satellites. (Courtesy NSIDC) Toboggan Glacier, Alaska, in 1909. This image one of a pair of photographs available through the “Repeat Photography of Glaciers” portion of NSIDC’s online Glacier Photograph Collection. These photograph pairs illustrate the dramatic changes that researchers have observed in glaciers worldwide over the past century. (Photograph courtesy of Sidney Paige/USGS Photo Library, available through NSIDC’s online Glacier Photograph Collection). Members of the IceTrek expedition practiced installing their meteorological equipment on this small Antarctic iceberg, nicknamed “Chip,” before installing the equipment permanently on larger icebergs. (Courtesy Ted Scambos, NSIDC) Supporting Cryospheric Research Since 1976 Supporting Cryospheric Research Since 1976 ii Supporting Cryospheric Research Since 1976 Contents Table of Contents Introduction 1 Highlights 3 Data Management at NSIDC 5 Programs 10 The Distributed Active Archive Center (DAAC) 10 The Arctic System Science (ARCSS) Data Coordination Center (ADCC) 14 U.S. -
Siple Dome Ice Reveals Two Modes of Millennial CO2 Change During the Last Ice Age
ARTICLE Received 4 Dec 2013 | Accepted 26 Mar 2014 | Published 29 Apr 2014 DOI: 10.1038/ncomms4723 OPEN Siple Dome ice reveals two modes of millennial CO2 change during the last ice age Jinho Ahn1 & Edward J. Brook2 Reconstruction of atmospheric CO2 during times of past abrupt climate change may help us better understand climate-carbon cycle feedbacks. Previous ice core studies reveal simultaneous increases in atmospheric CO2 and Antarctic temperature during times when Greenland and the northern hemisphere experienced very long, cold stadial conditions during the last ice age. Whether this relationship extends to all of the numerous stadial events in the Greenland ice core record has not been clear. Here we present a high-resolution record of atmospheric CO2 from the Siple Dome ice core, Antarctica for part of the last ice age. We find that CO2 does not significantly change during the short Greenlandic stadial events, implying that the climate system perturbation that produced the short stadials was not strong enough to substantially alter the carbon cycle. 1 School of Earth and Environmental Sciences, Seoul National University, Seoul 151742, Korea. 2 College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA. Correspondence and requests for materials should be addressed to J.A. (email: [email protected]). NATURE COMMUNICATIONS | 5:3723 | DOI: 10.1038/ncomms4723 | www.nature.com/naturecommunications 1 & 2014 Macmillan Publishers Limited. All rights reserved. ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/ncomms4723 ce core records from Greenland reveal a detailed history of the last ice age, marine sediment records indicate shoaled abrupt climate change during the last glacial period. -
Blue Sky Airlines
GPS Support to the National Science Foundation Office of Polar Programs 2001-2002 Season Report GPS Support to the National Science Foundation Office of Polar Programs 2001-2002 Season Report April 15, 2002 Bjorn Johns Chuck Kurnik Shad O’Neel UCAR/UNAVCO Facility University Corporation for Atmospheric Research 3340 Mitchell Lane Boulder, CO 80301 (303) 497-8034 www.unavco.ucar.edu Support funded by the National Science Foundation Office of Polar Programs Scientific Program Order No. 2 (EAR-9903413) to Cooperative Agreement No. 9732665 Cover photo: Erebus Ice Tongue Mapping – B-017 1 UNAVCO 2001-2002 Report Table of Contents: Summary........................................................................................................................................................ 3 Table 1 – 2001-2001 Antarctic Support Provided................................................................................. 4 Table 2 – 2001 Arctic Support Provided................................................................................................ 4 Science Support............................................................................................................................................. 5 Training.................................................................................................................................................... 5 Field Support........................................................................................................................................... 5 Data Processing .................................................................................................................................... -
Ice Stream Formation
Ice stream formation Christian Schoof1, and Elisa Mantelli2 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada 2AOS Program, Princeton University, Princeton, USA November 6, 2020 Abstract Ice streams are bands of fast-flowing ice in ice sheets. We investigate their formation as an example of spontaneous pattern formation, based on positive feedbacks between dissipa- tion and basal sliding. Our focus is on temperature-dependent subtemperate sliding, where faster sliding leads to enhanced dissipation and hence warmer temperatures, weakening the bed further, although we also treat a hydromechanical feedback mechanism that operates on fully molten beds. We develop a novel thermomechanical model capturing ice-thickness scale physics in the lateral direction while assuming the the flow is shallow in the main downstream direction. Using that model, we show that formation of a steady-in-time pattern can occur by the amplification in the downstream direction of noisy basal conditions, and often leads to the establishment of a clearly-defined ice stream separated from slowly-flowing, cold-based ice ridges by narrow shear margins, with the ice stream widening in the downstream direction. We are able to show that downward advection of cold ice is the primary stabilizing mechanism, and give an approximate, analytical criterion for pattern formation. 1 Introduction Ice streams are narrow bands of fast flow within otherwise more slowly-flowing ice sheets, often forming near the margin or grounding line of the ice sheet as outlets that can carry the majority of the ice discharged [1]. Some ice streams are confined to topographic lows that channelize flow [2], but not all, and those that are not controlled by topography may occur in parallel arrays of roughly similar ice streams. -
A Water-Piracy Hypothesis for the Stagnation of Ice Stream C, Antarctica
Annals of Glaciology 20 1994 (: International Glaciological Society A water-piracy hypothesis for the stagnation of Ice Stream C, Antarctica R. B. ALLEY, S. AXANDAKRISHXAN, Ear/h .~)'stem Science Center and Department or Geosciences, The Pennsyfuania State Unil!ersi~y, Universi~)' Park, PA 16802, U.S.A. C. R. BENTLEY AND N. LORD Geopl~)!.\icaland Polar Research Center, UnilJersit] or vVisconsin-Aladison, /vfadison, IYJ 53706, U.S.A. ABSTRACT. \Vatcr piracy by Icc Stream B, West Antarctica, may bave caused neighboring Icc Stream C to stop. The modern hydrologic potentials near the ups'tream cnd of the main trunk o[ Ice Stream C are directing water [rom the C catchment into Ice Stream B. Interruption of water supply from the catchment would have reduced water lubrication on bedrock regions projecting through lubricating basal till and stopped the ice stream in a tCw years or decades, short enough to appear almost instantaneous. This hypothesis explains several new data sets from Ice Stream C and makes predictions that might be testable. INTRODUCTION large challenge to glaciological research. Tn seeki ng to understand it, we may learn much about the behavior of The stability of the West Antarctic ice sheet is related to ice streams. the behavior of the fast-moving ice streams that drain it. ~luch effort thus has been directed towards under- standing these ice streams. The United States program PREVIOUS HYPOTHESES has especially focused on those ice streams :A E) flowing across the Siple Coast into the Ross Ice Shelf Among the The behavior of Ice Stream C has provoked much most surprising discoveries on the Siple Coast icc streams speculation.