The Dynamics and Mass Budget of Aretic Glaciers
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Internal Geometry and Evolution of Moulins
Journal of Glaciology, Vol. 34, No. 117 , 1988 INTERNAL GEOMETRY AND EVOLUTION OF MOULINS, STORGLACVlREN,~DEN By PER HOLMLUND (Department of Physical Geography, University of Stockholm, S-106 91 Stockholm, Sweden) ABSTRACT. The initial conditions needed for formation of moulins are crevasses and a supply of melt water. Water pouring into a crevasse may fill it until it overflows at the lowest point, which is normally near the margin. However, as the crevasse deepens, it intersects englacial channels through which the water can drain. These channels may be finger-tip tributaries in a dendritic system such as that described by Shreve (1972) and observed by Raymond and Harrison (1975). When the crevasse closes, heat in the melt water 'keeps the connection open and a moulin is formed. The englacial channel enlarges rapidly by melting, utilizing mechanical energy released by the descending water. Descents into moulins, and mapping of structures exposed at the surface after many years of melting, demonstrate that the drainage channels leading down from the bottoms of the moulins have inclinations of 0-45 0 from the vertical. These channels trend in the direction of the original crevasse but appear to be deeper than the expected depth of the crevasse. They have not, even at depths of 50--60 m, become normal to the equipotential planes described by Shreve. INTRODUCTION Fig . 1. Map showing the location of Storglaciiiren. Moulins, or "glacial mills" as they are sometimes called, are one of the more dramatic features of glacier surfaces. point (Schytt, 1968; Hooke and others, 1983), the ice Water plunging into a large moulin presents an awesome surface is presumably impermeable. -
Emplacement of a Silicic Lava Dome Through a Crater Glacier: Mount St Helens, 2004–06
14 Annals of Glaciology 45 2007 Emplacement of a silicic lava dome through a crater glacier: Mount St Helens, 2004–06 Joseph S. WALDER, Richard G. LaHUSEN, James W. VALLANCE, Steve P. SCHILLING United States Geological Survey, Cascades Volcano Observatory, 1300 Southeast Cardinal Court, Vancouver, Washington WA 98683-9589, USA E-mail: [email protected] ABSTRACT. The process of lava-dome emplacement through a glacier was observed for the first time after Mount St Helens reawakened in September 2004. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry and geodetic measure- ments document glacier deformation of an extreme variety, with strain rates of extraordinary magnitude as compared to normal alpine glaciers. Unlike normal temperate glaciers, the crater glacier shows no evidence of either speed-up at the beginning of the ablation season or diurnal speed fluctuations during the ablation season. Thus there is evidently no slip of the glacier over its bed. The most reasonable explanation for this anomaly is that meltwater penetrating the glacier is captured by a thick layer of coarse rubble at the bed and then enters the volcano’s groundwater system rather than flowing through a drainage network along the bed. INTRODUCTION ice bodies have been successively squeezed between the Since October 2004, a lava dome has been emplaced first growing lava dome and the crater walls. through, and then alongside, glacier ice in the crater of Several examples of lava-dome emplacement into ice Mount St Helens, Washington state, US. -
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. -
1961 Climbers Outing in the Icefield Range of the St
the Mountaineer 1962 Entered as second-class matter, April 8, 1922, at Post Office in Seattle, Wash., under the Act of March 3, 1879. Published monthly and semi-monthly during March and December by THE MOUNTAINEERS, P. 0. Box 122, Seattle 11, Wash. Clubroom is at 523 Pike Street in Seattle. Subscription price is $3.00 per year. The Mountaineers To explore and study the mountains, forests, and watercourses of the Northwest; To gather into permanent form the history and traditions of this region; To preserve by the encouragement of protective legislation or otherwise the natural beauty of Northwest America; To make expeditions into these regions in fulfillment of the above purposes; To encourage a spirit of good fellowship among all lovers of outdoor Zif e. EDITORIAL STAFF Nancy Miller, Editor, Marjorie Wilson, Betty Manning, Winifred Coleman The Mountaineers OFFICERS AND TRUSTEES Robert N. Latz, President Peggy Lawton, Secretary Arthur Bratsberg, Vice-President Edward H. Murray, Treasurer A. L. Crittenden Frank Fickeisen Peggy Lawton John Klos William Marzolf Nancy Miller Morris Moen Roy A. Snider Ira Spring Leon Uziel E. A. Robinson (Ex-Officio) James Geniesse (Everett) J. D. Cockrell (Tacoma) James Pennington (Jr. Representative) OFFICERS AND TRUSTEES : TACOMA BRANCH Nels Bjarke, Chairman Wilma Shannon, Treasurer Harry Connor, Vice Chairman Miles Johnson John Freeman (Ex-Officio) (Jr. Representative) Jack Gallagher James Henriot Edith Goodman George Munday Helen Sohlberg, Secretary OFFICERS: EVERETT BRANCH Jim Geniesse, Chairman Dorothy Philipp, Secretary Ralph Mackey, Treasurer COPYRIGHT 1962 BY THE MOUNTAINEERS The Mountaineer Climbing Code· A climbing party of three is the minimum, unless adequate support is available who have knowledge that the climb is in progress. -
Checklist of Lichenicolous Fungi and Lichenicolous Lichens of Svalbard, Including New Species, New Records and Revisions
Herzogia 26 (2), 2013: 323 –359 323 Checklist of lichenicolous fungi and lichenicolous lichens of Svalbard, including new species, new records and revisions Mikhail P. Zhurbenko* & Wolfgang von Brackel Abstract: Zhurbenko, M. P. & Brackel, W. v. 2013. Checklist of lichenicolous fungi and lichenicolous lichens of Svalbard, including new species, new records and revisions. – Herzogia 26: 323 –359. Hainesia bryonorae Zhurb. (on Bryonora castanea), Lichenochora caloplacae Zhurb. (on Caloplaca species), Sphaerellothecium epilecanora Zhurb. (on Lecanora epibryon), and Trimmatostroma cetrariae Brackel (on Cetraria is- landica) are described as new to science. Forty four species of lichenicolous fungi (Arthonia apotheciorum, A. aspicili- ae, A. epiphyscia, A. molendoi, A. pannariae, A. peltigerina, Cercidospora ochrolechiae, C. trypetheliza, C. verrucosar- ia, Dacampia engeliana, Dactylospora aeruginosa, D. frigida, Endococcus fusiger, E. sendtneri, Epibryon conductrix, Epilichen glauconigellus, Lichenochora coppinsii, L. weillii, Lichenopeltella peltigericola, L. santessonii, Lichenostigma chlaroterae, L. maureri, Llimoniella vinosa, Merismatium decolorans, M. heterophractum, Muellerella atricola, M. erratica, Pronectria erythrinella, Protothelenella croceae, Skyttella mulleri, Sphaerellothecium parmeliae, Sphaeropezia santessonii, S. thamnoliae, Stigmidium cladoniicola, S. collematis, S. frigidum, S. leucophlebiae, S. mycobilimbiae, S. pseudopeltideae, Taeniolella pertusariicola, Tremella cetrariicola, Xenonectriella lutescens, X. ornamentata, -
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. -
Perennial Ice and Snow Masses
" :1 i :í{' ;, fÎ :~ A contribution to the International Hydrological' Decade Perennial ice and snow masses A guide for , compilation and assemblage of data for a world inventory unesco/iash " ' " I In this series: '1 Perennial Ice and Snow Masses. A Guide for Compilation and Assemblage of Data for a World Inventory. 2 Seasonal Snow Cower. A Guide for Measurement, Compilation and Assemblage of Data. 3 Variations of Existing Glaciers. A Guide to International Practices for their Measurement.. 4 Antartie Glaciology in the International Hydrological Decade. S Combined Heat, Ice and Water Balances at Selected Glacier Basins. A Guide for Compilation and Assemblage of Data for Glacier Mass Balance ( Measurements. (- ~------------------ ", _.::._-~,.:- r- ,.; •.'.:-._ ': " :;-:"""':;-iij .if( :-:.:" The selection and presentation of material and the opinions expressed in this publication are the responsibility of the authors concerned 'and do not necessarily reflect , , the views of Unesco. Nor do the designations employed or the presentation of the material imply the expression of any opinion whatsoever on the part of Unesco concerning the legal status of any country or territory, or of its authorities, or concerning the frontiers of any country or territory. Published in 1970 by the United Nations Bducational, Scientific and Cultal al OrganIzatIon, Place de Fontenoy, 75 París-r-. Printed by Imprimerie-Reliure Marne. © Unesco/lASH 1970 Printed in France SC.6~/XX.1/A. ...•.•• :. ;'::'~~"::::'??<;~;~8~~~ (,: :;H,.,Wfuif:: Preface The International Hydrological Decade _(IHD) As part of Unesco's contribution to the achieve- 1965-1974was launched hy the General Conference ment of the objectives of, the IHD the General of Unesco at its thirteenth session to promote Conference authorized the Director-General to international co-operation in research and studies collect, exchange and disseminate information and the training of specialists and technicians in concerning research on scientific hydrology and to scientific hydrology. -
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. -
Glacier (And Ice Sheet) Mass Balance
Glacier (and ice sheet) Mass Balance The long-term average position of the highest (late summer) firn line ! is termed the Equilibrium Line Altitude (ELA) Firn is old snow How an ice sheet works (roughly): Accumulation zone ablation zone ice land ocean • Net accumulation creates surface slope Why is the NH insolation important for global ice• sheetSurface advance slope causes (Milankovitch ice to flow towards theory)? edges • Accumulation (and mass flow) is balanced by ablation and/or calving Why focus on summertime? Ice sheets are very sensitive to Normal summertime temperatures! • Ice sheet has parabolic shape. • line represents melt zone • small warming increases melt zone (horizontal area) a lot because of shape! Slightly warmer Influence of shape Warmer climate freezing line Normal freezing line ground Furthermore temperature has a powerful influence on melting rate Temperature and Ice Mass Balance Summer Temperature main factor determining ice growth e.g., a warming will Expand ablation area, lengthen melt season, increase the melt rate, and increase proportion of precip falling as rain It may also bring more precip to the region Since ablation rate increases rapidly with increasing temperature – Summer melting controls ice sheet fate* – Orbital timescales - Summer insolation must control ice sheet growth *Not true for Antarctica in near term though, where it ʼs too cold to melt much at surface Temperature and Ice Mass Balance Rule of thumb is that 1C warming causes an additional 1m of melt (see slope of ablation curve at right) -
Icing Mound on Sadlerochit River, Alaska
Short Papers and Notes ICING MOUND ON SADLERO- Sadlerochithas emerged from the CHIT RIVER, ALASKA* mountains, has arelatively low gra- dient and flows in a broad, braided bed Icing mounds- small to large domes, characterized by manyanastomosing mounds,and ridges resulting from an shallowchannels separated by bare, upwardarching of soiland ice asso- gravelly and bouldery bars (Fig. 2). AS ciated with fields of aufeis - have been is characteristic of all riversof the Arc- described in detailfor Siberia1. Icing tic Slope, the change from a single deep mounds have also been mentioned brief- channel to a braided pattern of many ly inconnection with aufeisfields in shallow channels allows the formation Alaskaby Leffigwell (ref. 2, p. 158) of an aufeis field every year near the and Taber (ref. 3, p. 1528; ref. 4, p. 249), mountain front. During the fall the but there is little descriptive literature shallow channels freeze early and the on this phenomenon in theNorth Amer- obstruction of the resulting ice causes ican Arctic. One such icing mound was the river to overflow its bars;this over- examined briefly by the author on June flow then freezes and by repeated freez- 25,1959 during the course of a trip down ing,overflow and freezingsuccessive the SadlerochitRiver in northeastern layers of ice are built up toform an Alaska (Fig. 1). aufeis field. Another factor contributing Fig. 1. Locationmap, Arctic Slope, Alaska. The SadlerochitRiver rises in the to the formation of large aufeis fields is Franklin Mountains of the eastern a source of water that persists for some Brooks Range and flows northwardin a time after freezingbegins. -
Perennial Ice and Snow Masses
Technical papers in hydrology 1 In this series: 1 Perennial Ice and Snow Masses. A Guide for Compilation and Assemblage of Data for a World Inventory. 2 Seasonal Snow Cower. A Guide for Measurement, Compilation and Assemblage of Data. 3 Variations of Existing Glaciers. A Guide to International Practices for their Measurement. 4 Antartic Glaciology in the International Hydrological Decade. 5 Combined Heat, Ice and Water Balances at Selected Glacier Basins. A Guide for Compilation and Assemblage of Data for Glacier Mass Balance Measurements. A contribution to the International Hydrological Decade Perennial ice and snow masses A guide for compilation and assemblage of data for a world inventory nesco/iash The selection and presentation of material and the opinions expressed in this publication are the responsibility of the authors concerned and do not necessarily reflect the views of Unesco. Nor do the designations employed or the presentation of the material imply the expression of any opinion whatsoever on the part of Unesco concerning the legal status of any country or territory, or of its authorities, or concerning the frontiers of any country or territory. Published in 1970 by the United Nations Educational, Scientific and Cultural Organization, Place de Fontenoy, 75 Paris-7C. Printed by Imprimerie-Reliure Mame. © Unesco/I ASH 1970 Printed in France SC.68/XX.1/A. Preface The International Hydrological Decade (IHD) As part of Unesco's contribution to the achieve 1965-1974 was launched by the General Conference ment of the objectives of the IHD the General of Unesco at its thirteenth session to promote Conference authorized the Director-General to international co-operation in research and studies collect, exchange and disseminate information and the training of specialists and technicians in concerning research on scientific hydrology and to scientific hydrology. -
Historical and Recent Aufeis, the Indigirka River Basin (Russia)
1 Historical and recent aufeis, the Indigirka river basin 2 (Russia) 3 *Olga Makarieva1,2,, Andrey Shikhov3, Nataliia Nesterova2,4, Andrey Ostashov2 4 1Melnikov Permafrost Institute of RAS, Yakutsk 5 2St. Petersburg State University, St. Petersburg 6 3Perm State University, Perm 7 4State Hydrological institute, St. Petersburg 8 RUSSIA 9 *[email protected] 10 Abstract: A detailed spatial geodatabase of aufeis (or naleds in Russian) within the 11 Indigirka River watershed (305 000 km2), Russia, was compiled from historical Russian 12 publications (year 1958), topographic maps (years 1970–1980’s), and Landsat images (year 13 2013-2017). Identification of aufeis by late-spring Landsat images was performed with a semi- 14 automated approach according to Normalized Difference Snow Index (NDSI) and additional 15 data. After this, a cross-reference index was set for each aufeis, to link and compare historical 16 and satellite-based aufeis data sets. 17 The aufeis coverage varies from 0.26 to 1.15% in different sub-basins within the 18 Indigirka River watershed. The digitized historical archive (Cadastre, 1958) contains the 19 coordinates and characteristics of 896 aufeis with total area of 2064 km2. The Landsat-based 20 dataset included 1213 aufeis with a total area of 1287 km2. Accordingly, the satellite-derived 21 total aufeis area is 1.6 times less than the Cadastre (1958) dataset. However, more than 600 22 aufeis identified from Landsat images are missing in the Cadastre (1958) archive. It is 23 therefore possible that the conditions for aufeis formation may have changed from the mid- 24 20th century to the present.