Glacial Landforms and Features
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Surface Mass Balance of Small Glaciers on James Ross Island
Journal of Glaciology (2018), 64(245) 349–361 doi: 10.1017/jog.2018.17 © The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons. org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015 ̌ ̌ ̌ ZBYNEK ENGEL,1* KAMIL LÁSKA,2 DANIEL NÝVLT,2 ZDENEK STACHON2 1Department of Physical Geography and Geoecology, Faculty of Science, Charles University, Praha, Czech Republic 2Department of Geography, Faculty of Science, Masaryk University, Brno, Czech Republic *Correspondence: Zbyněk Engel <[email protected]> ABSTRACT. Two small glaciers on James Ross Island, the north-eastern Antarctic Peninsula, experi- enced surface mass gain between 2009 and 2015 as revealed by field measurements. A positive cumulative surface mass balance of 0.57 ± 0.67 and 0.11 ± 0.37 m w.e. was observed during the 2009–2015 period on Whisky Glacier and Davies Dome, respectively. The results indicate a change from surface mass loss that prevailed in the region during the first decade of the 21st century to predominantly positive surface mass balance after 2009/10. The spatial pattern of annual surface mass-balance distribution implies snow redistribution by wind on both glaciers. The mean equilibrium line altitudes for Whisky Glacier (311 ± 16 m a.s.l.) and Davies Dome (393 ± 18 m a.s.l.) are in accordance with the regional data indicating 200–300 m higher equilibrium line on James Ross and Vega Islands compared with the South Shetland Islands. -
Basal Control of Supraglacial Meltwater Catchments on the Greenland Ice Sheet
The Cryosphere, 12, 3383–3407, 2018 https://doi.org/10.5194/tc-12-3383-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Basal control of supraglacial meltwater catchments on the Greenland Ice Sheet Josh Crozier1, Leif Karlstrom1, and Kang Yang2,3 1University of Oregon Department of Earth Sciences, Eugene, Oregon, USA 2School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China 3Joint Center for Global Change Studies, Beijing 100875, China Correspondence: Josh Crozier ([email protected]) Received: 5 April 2018 – Discussion started: 17 May 2018 Revised: 13 October 2018 – Accepted: 15 October 2018 – Published: 29 October 2018 Abstract. Ice surface topography controls the routing of sur- sliding regimes. Predicted changes to subglacial hydraulic face meltwater generated in the ablation zones of glaciers and flow pathways directly caused by changing ice surface to- ice sheets. Meltwater routing is a direct source of ice mass pography are subtle, but temporal changes in basal sliding or loss as well as a primary influence on subglacial hydrology ice thickness have potentially significant influences on IDC and basal sliding of the ice sheet. Although the processes spatial distribution. We suggest that changes to IDC size and that determine ice sheet topography at the largest scales are number density could affect subglacial hydrology primarily known, controls on the topographic features that influence by dispersing the englacial–subglacial input of surface melt- meltwater routing at supraglacial internally drained catch- water. ment (IDC) scales ( < 10s of km) are less well constrained. Here we examine the effects of two processes on ice sheet surface topography: transfer of bed topography to the surface of flowing ice and thermal–fluvial erosion by supraglacial 1 Introduction meltwater streams. -
Calving Processes and the Dynamics of Calving Glaciers ⁎ Douglas I
Earth-Science Reviews 82 (2007) 143–179 www.elsevier.com/locate/earscirev Calving processes and the dynamics of calving glaciers ⁎ Douglas I. Benn a,b, , Charles R. Warren a, Ruth H. Mottram a a School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK b The University Centre in Svalbard, PO Box 156, N-9171 Longyearbyen, Norway Received 26 October 2006; accepted 13 February 2007 Available online 27 February 2007 Abstract Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the ‘calving problem’ involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. -
Seismic Model Report.Pdf
Scientific Report GEFSC Loan 925 The Character and Extent of subglacial Deformation and its Links to Glacier Dynamics in the Tarfala Basin, northern Sweden Jeffrey Evans, David Graham, and Joseph Pomeroy Polar and Alpine Research Group, Loughborough University ABSTRACT A pilot passive seismology experiment was conducted across the main overdeepening of Storglaciaren in the Tarfala Basin, northern Sweden, in July 2010, to see whether basal microseismic waveforms could be detected beneath a small polythermal arctic glacier and to investigate the spatial and temporal distribution of such waveforms in relation to known glacier flow dynamics. The high ablation rate made it difficult to keep geophones buried and well- coupled to the glacier during the experiment and reduced the number of days of good quality data collection. Event counts and the subsequent characterisation of typical and atypical waveforms showed that the dominant waveforms detected were from near-surface events such as crevassing. Although basal sliding is known to occur in the overdeepening, no convincing examples of basal waveforms were detected, which suggests basal microseismic signals are rare or difficult to detect beneath polythermal glaciers like Storglaciaren, a finding that is consistent with results from alpine glaciers in Switzerland. The data- set could prove useful to glaciologists interested in the dynamics of near-surface events such as crevassing, the opening and closing of englacial water conduits, or temporal and spatial changes in the glacier’s stress field. Background Smith (2006) found that pervasive soft-bed deformation characterised parts of the Rutland Ice Stream in West Antarctica and produced 6 times fewer basal microseismic signals than regions where basal sliding or stick slip movement dominated. -
COLD-BASED GLACIERS in the WESTERN DRY VALLEYS of ANTARCTICA: TERRESTRIAL LANDFORMS and MARTIAN ANALOGS: David R
Lunar and Planetary Science XXXIV (2003) 1245.pdf COLD-BASED GLACIERS IN THE WESTERN DRY VALLEYS OF ANTARCTICA: TERRESTRIAL LANDFORMS AND MARTIAN ANALOGS: David R. Marchant1 and James W. Head2, 1Department of Earth Sciences, Boston University, Boston, MA 02215 [email protected], 2Department of Geological Sciences, Brown University, Providence, RI 02912 Introduction: Basal-ice and surface-ice temperatures are contacts and undisturbed underlying strata are hallmarks of cold- key parameters governing the style of glacial erosion and based glacier deposits [11]. deposition. Temperate glaciers contain basal ice at the pressure- Drop moraines: The term drop moraine is used here to melting point (wet-based) and commonly exhibit extensive areas describe debris ridges that form as supra- and englacial particles of surface melting. Such conditions foster basal plucking and are dropped passively at margins of cold-based glaciers (Fig. 1a abrasion, as well as deposition of thick matrix-supported drift and 1b). Commonly clast supported, the debris is angular and sheets, moraines, and glacio-fluvial outwash. Polar glaciers devoid of fine-grained sediment associated with glacial abrasion include those in which the basal ice remains below the pressure- [10, 12]. In the Dry Valleys, such moraines may be cored by melting point (cold-based) and, in extreme cases like those in glacier ice, owing to the insulating effect of the debris on the the western Dry Valleys region of Antarctica, lack surface underlying glacier. Where cored by ice, moraine crests can melting zones. These conditions inhibit significant glacial exceed the angle of repose. In plan view, drop moraines closely erosion and deposition. -
Inferred Basal Friction and Surface Mass Balance of the Northeast
The Cryosphere, 8, 2335–2351, 2014 www.the-cryosphere.net/8/2335/2014/ doi:10.5194/tc-8-2335-2014 © Author(s) 2014. CC Attribution 3.0 License. Inferred basal friction and surface mass balance of the Northeast Greenland Ice Stream using data assimilation of ICESat (Ice Cloud and land Elevation Satellite) surface altimetry and ISSM (Ice Sheet System Model) E. Larour1, J. Utke3, B. Csatho4, A. Schenk4, H. Seroussi1, M. Morlighem2, E. Rignot1,2, N. Schlegel1, and A. Khazendar1 1Jet Propulsion Laboratory – California Institute of Technology, 4800 Oak Grove Drive MS 300-323, Pasadena, CA 91109-8099, USA 2University of California Irvine, Department of Earth System Science, Croul Hall, Irvine, CA 92697-3100, USA 3Argonne National Lab, Argonne, IL 60439, USA 4Department of Geological Sciences, University at Buffalo, Buffalo, NY, USA Correspondence to: E. Larour ([email protected]) Received: 5 April 2014 – Published in The Cryosphere Discuss.: 8 May 2014 Revised: 9 September 2014 – Accepted: 30 September 2014 – Published: 15 December 2014 Abstract. We present a new data assimilation method within 1 Introduction the Ice Sheet System Model (ISSM) framework that is capa- ble of assimilating surface altimetry data from missions such Global mean sea level (GMSL) rise observations show an as ICESat (Ice Cloud and land Elevation Satellite) into re- overall budget in which freshwater contribution from the po- constructions of transient ice flow. The new method relies on lar ice sheets represents a significant portion (Church and algorithmic differentiation to compute gradients of objective White, 2006, 2011; Stocker et al., 2013), which is actually functions with respect to model forcings. -
The Dynamics and Mass Budget of Aretic Glaciers
DA NM ARKS OG GRØN L ANDS GEO L OG I SKE UNDERSØGELSE RAP P ORT 2013/3 The Dynamics and Mass Budget of Aretic Glaciers Abstracts, IASC Network of Aretic Glaciology, 9 - 12 January 2012, Zieleniec (Poland) A. P. Ahlstrøm, C. Tijm-Reijmer & M. Sharp (eds) • GEOLOGICAL SURVEY OF D EN MARK AND GREENLAND DANISH MINISTAV OF CLIMATE, ENEAGY AND BUILDING ~ G E U S DANMARKS OG GRØNLANDS GEOLOGISKE UNDERSØGELSE RAPPORT 201 3 / 3 The Dynamics and Mass Budget of Arctic Glaciers Abstracts, IASC Network of Arctic Glaciology, 9 - 12 January 2012, Zieleniec (Poland) A. P. Ahlstrøm, C. Tijm-Reijmer & M. Sharp (eds) GEOLOGICAL SURVEY OF DENMARK AND GREENLAND DANISH MINISTRY OF CLIMATE, ENERGY AND BUILDING Indhold Preface 5 Programme 6 List of participants 11 Minutes from a special session on tidewater glaciers research in the Arctic 14 Abstracts 17 Seasonal and multi-year fluctuations of tidewater glaciers cliffson Southern Spitsbergen 18 Recent changes in elevation across the Devon Ice Cap, Canada 19 Estimation of iceberg to the Hansbukta (Southern Spitsbergen) based on time-lapse photos 20 Seasonal and interannual velocity variations of two outlet glaciers of Austfonna, Svalbard, inferred by continuous GPS measurements 21 Discharge from the Werenskiold Glacier catchment based upon measurements and surface ablation in summer 2011 22 The mass balance of Austfonna Ice Cap, 2004-2010 23 Overview on radon measurements in glacier meltwater 24 Permafrost distribution in coastal zone in Hornsund (Southern Spitsbergen) 25 Glacial environment of De Long Archipelago -
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. -
Learning to Speak Like a Glaciologist
Conversational Glaciology Answers Learning to speak like a glaciologist Matching Exercise A sharp knife-edge ridge of high ground that forms between arête two corries where they are cutting back into the rock A form of erosion that is caused by rocks and sediment at the abrasion base of glaciers grinding along the ground beneath acting like a giant sand-paper file to scrape and smooth rocks below Sediment material that is dragged along the base of a glacier bedload or ice sheet, acting to erode the ground beneath A mixture of sands, clays and boulders carried by a glacier and boulder then deposited over a large area clay (till) As ice slowly moves forward it pushes material forwards ahead bulldozing of it like a bulldozer The process whereby blocks of ice collapse and fall from the calving snout of the glacier, often into a glacial lagoon An armchair-shaped rounded hollow in a mountainside that is formed by a combination of glacial erosion, rotational slip and corrie /cwm / freeze-thaw weathering. When the ice melts it leaves a cirque depression in the rock A deep crack found in the surface of an ice-sheet or glacier, crevasse these are often buried under snow and can be incredibly dangerous if unseen A hill landform that is formed by the deposition of glacial till (boulder clay) as a glacier moves, they are usually oval in shape drumlin and their long axis is parallel to the direction of ice The imaginary boundary line between the ablation zone (where equilibrium ice is lost) and accumulation zone (where ice is gained) line The process of material being broken down and worn away, erosion which can happen in various ways, e.g. -
Friction at the Base of a Glacier
WXW::kTi*[[Hl*f,}H Mitteilungen 101 Friction at the base of a glacier Jürg Schweizer Zürich, 1989 Herausgeber: Prof. Dr. D. Vischer Preface Any sliding process depends on the driving and the retaining forces. If the slidlng mass is cfearfy defined and its motion is only due to gravity, the driving forces can easily be de- termined i.e. the component of weight parallel to the slidlng interface. The retaining forces, howeverf are more difficult to eval-uate, since onJ.y crude empirical rel.ations for the as- sessment of the friction exist. fn modern glaci-o]ogy a fot of work is involved in in- vestigating the conditions at the gJ-acier bed and Cetermining the sliding motion of a glacier. The nature and the physical processes 'down at the base give rise to many questlons: Which sort of friction is adequate? What is the influence of the subglacial hydraulics and what role does the debris concen- tratlon of the basal ice play? The author of the present report, Dr. Jürg Schweizer, deals with these questions. He establishes different types of friction for typical bed characteristics and, to a certain extent, derives qualitative anal.ytical solutions. The appli- cation of the friction model of Ha1let requires a numerical treatment using the finite element method. The results show that the debris concentration in the basal ice and the sub- glacial {ater pressure dominate the sliding process. Accordingly thi-s study foll-ows the extensive field observatlons, carried out during the Last years by the glaci- ologicaL section of the VAW, investigating the relation be- tween the sliding velocity and the subgfaciaf water pressure. -
Thermal Structure and Basal Sliding Parametrisation at Pine Island Glacier – a 3-D Full-Stokes Model Study
The Cryosphere, 9, 675–690, 2015 www.the-cryosphere.net/9/675/2015/ doi:10.5194/tc-9-675-2015 © Author(s) 2015. CC Attribution 3.0 License. Thermal structure and basal sliding parametrisation at Pine Island Glacier – a 3-D full-Stokes model study N. Wilkens1,2, J. Behrens3, T. Kleiner2, D. Rippin4, M. Rückamp2, and A. Humbert2,5 1Institute for Geophysics, University of Hamburg, Germany 2Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany 3Numerical Methods in Geosciences, University of Hamburg, Germany 4Environment Department, University of York, Heslington, UK 5Department of Geosciences, University of Bremen, Germany Correspondence to: N. Wilkens ([email protected]) Received: 21 August 2014 – Published in The Cryosphere Discuss.: 16 September 2014 Revised: 16 March 2015 – Accepted: 17 March 2015 – Published: 13 April 2015 Abstract. Pine Island Glacier is one of the fastest changing Park et al., 2013; Helm et al., 2014). Additionally, the cur- glaciers of the Antarctic Ice Sheet and therefore of scientific rently observed mass loss from the Antarctic Ice Sheet is also interest. The glacier holds enough ice to raise the global sea concentrated in the area around PIG (Horwath and Dietrich, level significantly ( ∼ 0.5 m) when fully melted. The ques- 2009; Shepherd et al., 2012). Thus PIG shows an increased tion addressed by numerous modelling studies of the glacier contribution to global sea level rise (Mouginot et al., 2014). focuses on whether the observed changes are a start of an The bed lies below sea level in large areas, making it part uncontrolled and accelerating retreat. -
Sliding Velocity Fluctuations and Subglacial Hydrology Over the Last Two Decades on Argentière Glacier, Mont Blanc Area
Journal of Glaciology (2016), 62(235) 805–815 doi: 10.1017/jog.2016.35 © The Author(s) 2016. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons. org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Sliding velocity fluctuations and subglacial hydrology over the last two decades on Argentière glacier, Mont Blanc area CHRISTIAN VINCENT,1 LUC MOREAU2 1Laboratoire de Glaciologie et Géophysique de l’Environnement, UJF/CNRS, Grenoble, France 2Edytem, CNRS, Université de Savoie, Chambéry, France Correspondence: Christian Vincent <[email protected]> ABSTRACT. The subglacial observatory beneath the Argentière glacier provides a rare opportunity to study the interactions between glacier sliding velocity and subglacial runoff. The sliding velocity has been monitored in this cavity almost continuously since 1997 and the resulting data indicate a decrease in annual sliding velocities over the last two decades. We found close relationships between annual surface velocity, sliding velocity and ice thickness. These relationships indicate that the ice-flow velocity changes do not depend on subglacial water runoff changes at the annual timescale. The seasonal mag- nitudes of sliding also show a decrease over the last two decades. At the seasonal timescale, sliding vel- ocity increases before or simultaneously with the large runoff increase in May, indicating a distributed drainage system. Conversely, at the end of the melt season, sliding velocity continues to decrease after the runoff returns to low winter values. The simultaneous increases of runoff and sliding velocity occur mainly before the spring transition.