Scaling of Instability Time-Scales of Antarctic Outlet Glaciers Based on One-Dimensional Similitude Analysis
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Heterogenous Thinning and Subglacial Lake Activity on Thwaites Glacier, West Antarctica Andrew O
https://doi.org/10.5194/tc-2020-80 Preprint. Discussion started: 9 April 2020 c Author(s) 2020. CC BY 4.0 License. Brief Communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica Andrew O. Hoffman1, Knut Christianson1, Daniel Shapero2, Benjamin E. Smith2, Ian Joughin2 1Department of Earth and Space Sciences, University of Washington, Seattle, 98115, United States of America 5 2Applied Physics Laboratory, University of Washington, 98115, United States of America Correspondence to: Andrew O. Hoffman ([email protected]) Abstract. A system of subglacial laKes drained on Thwaites Glacier from 2012-2014. To improve coverage for subsequent drainage events, we extended the elevation and ice velocity time series on Thwaites Glacier through austral winter 2019. These new observations document a second drainage cycle and identified two new laKe systems located in the western tributaries of 10 Thwaites and Haynes Glaciers. In situ and satellite velocity observations show temporary < 3% speed fluctuations associated with laKe drainages. In agreement with previous studies, these observations suggest that active subglacial hydrology has little influence on Thwaites Glacier thinning and retreat on decadal to centennial timescales. 1 Introduction Although subglacial laKes beneath the Antarctic Ice Sheet were first discovered more than 50 years ago (Robin et al., 1969; 15 Oswald and Robin, 1973), they remain one of the most enigmatic components of the subglacial hydrology system. Initially identified in ice-penetrating radar data as flat, bright specular reflectors (Oswald and Robin, 1973; Carter et al., 2007) subglacial laKes were thought to be relatively steady-state features of the basal hydrology system with little impact on the dynamics of the overlying ice on multi-year timescales. -
A Significant Acceleration of Ice Volume Discharge Preceded a Major Retreat of a West Antarctic Paleo–Ice Stream
https://doi.org/10.1130/G46916.1 Manuscript received 26 August 2019 Revised manuscript received 23 November 2019 Manuscript accepted 26 November 2019 © 2019 Geological Society of America. For permission to copy, contact [email protected]. A signifcant acceleration of ice volume discharge preceded a major retreat of a West Antarctic paleo–ice stream Philip J. Bart1 and Slawek Tulaczyk2 1 Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2 Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064, USA ABSTRACT SEDIMENT AND ICE DISCHARGE For the period between 14.7 and 11.5 cal. (calibrated) kyr B.P, the sediment fux of Bind- FROM THE PALEO–BINDSCHADLER schadler Ice Stream (BIS; West Antarctica) averaged 1.7 × 108 m3 a−1. This implies that BIS ICE STREAM velocity averaged 500 ± 120 m a−1. At a fner resolution, the data suggest two stages of ice Radiocarbon ages from benthic foramin- stream fow. During the frst 2400 ± 400 years of a grounding-zone stillstand, ice stream fow ifera (Bart et al., 2018) (Table 1) indicate that averaged 200 ± 90 m a−1. Following ice-shelf breakup at 12.3 ± 0.2 cal. kyr B.P., fow acceler- the paleo-BIS grounding line had retreated ated to 1350 ± 580 m a−1. The estimated ice volume discharge after breakup exceeds the bal- 70 km from its maximum (LGM) position by ance velocity by a factor of two and implies ice mass imbalance of −40 Gt a−1 just before the 14.7 ± 0.4 cal. -
Education Personal Research Interests Employment
Douglas Reed MacAyeal Department of the Geophysical Sciences The University of Chicago 5734 S. Ellis Ave. HGS 424 Chicago, IL Phone: (773) 702-8027 (o) (773) 752-6078 (h) (773) 702-9505 (f) (224) 500-7775 (c) [email protected] [email protected] last updated: March, 2020 Education 1983 Ph.D. Princeton University, Princeton, NJ Geophysical Fluid Dynamics advisor: Kirk Bryan 1979 M.S. University of Maine, Orono, ME Physics/Glaciology advisor: Robert Thomas 1976 Sc.B. Brown University, Providence, RI Physics Magna cum laude, honors in physics Personal Birth Date: 8 December, 1954; Age: 65 Birth Place: Boston, MA, USA Marital Status: Married, Linda A. MacAyeal (Sparks) Children: Leigh C. (MacAyeal) Kasten (Brown U., Sc.B.; Cornell U., DVM), Hannah R. MacAyeal (U. Penn, B.S., U. Penn Veterinary Medicine, DVM), Evan C. MacAyeal (Carleton College, B.A., Columbia University, Financial Engineering, M.S.) Research Interests The physical processes that determine the evolution of ice and climate on Earth over the past, present and future. Employment Department of the Geophysical Sciences, University of Chicago 1983-Present Professor (Asst. until 1987, Assoc. until 1992 and Full until present) Prior to 1983: I was a graduate student at Princeton University and University of Maine. Awards and Honors • 2019 Seligman Crystal, International Glaciological Society (IGS) • 2013 Nye Lecture, American Geophysical Union (AGU), Fall Meeting • 2010 Goldthwait Award (Polar Medal) of the Byrd Polar Research Center, Ohio State University • 2005 Provost’s Teaching Award of the University of Chicago • 2002 Quantrell Teaching Award of the University of Chicago • 1997 Richardson Medal of the IGS • 1988 James Macelwane Medal of the AGU • 1988 Fellow of the AGU • Antarctic geographic names: MacAyeal Ice Stream, MacAyeal Peak Teaching Experience • GeoSci 242: Geophysical Fluid Dynamics, I. -
Studies of Antarctic Ice Shelf Stability: Surface Melting, Basal Melting, and Ice Flow Dynamics
Studies of Antarctic ice shelf stability: surface melting, basal melting, and ice flow dynamics by Karen E. Alley B.A., Colgate University, 2012 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree of Doctor of Philosophy Department of Geological Sciences 2017 This thesis entitled: Studies of Antarctic ice shelf stability: Surface melting, basal melting, and ice flow dynamics written by Karen E. Alley has been approved for the Department of Geological Sciences James White Ted Scambos Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above-mentioned discipline. ii Alley, Karen Elizabeth (Ph.D., Department of Geological Sciences) Studies of Antarctic ice shelf stability: Surface melting, basal melting, and ice flow dynamics Thesis directed by Senior Research Scientist T.A. Scambos and Professor J.W.C. White Abstract: Floating extensions of ice sheets, known as ice shelves, play a vital role in regulating the rate of ice flow into the Southern Ocean from the Antarctic Ice Sheet. Shear stresses imparted by contact with islands, embayment walls, and other obstructions transmit “backstress” to grounded ice. Ice shelf collapse reduces or eliminates this backstress, increasing mass flux to the ocean and therefore rates of sea level rise. This dissertation presents studies that address three main factors that regulate ice shelf stability: surface melt, basal melt, and ice flow dynamics. The first factor, surface melt, is assessed using active microwave backscatter. -
Did Holocene Climate Changes Drive West Antarctic Grounding Line Retreat and Re-Advance?
https://doi.org/10.5194/tc-2020-308 Preprint. Discussion started: 19 November 2020 c Author(s) 2020. CC BY 4.0 License. Did Holocene climate changes drive West Antarctic grounding line retreat and re-advance? Sarah U. Neuhaus1, Slawek M. Tulaczyk1, Nathan D. Stansell2, Jason J. Coenen2, Reed P. Scherer2, Jill 5 A. Mikucki3, Ross D. Powell2 1Earth and Planetary Sciences, University oF CaliFornia Santa Cruz, Santa Cruz, CA, 95064, USA 2Department oF Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL, 60115, USA 3Department oF Microbiology, University oF Tennessee Knoxville, Knoxville, TN, 37996, USA 10 Correspondence to: Sarah U. Neuhaus ([email protected]) Abstract. Knowledge oF past ice sheet conFigurations is useFul For informing projections of Future ice sheet dynamics and For calibrating ice sheet models. The topology oF grounding line retreat in the Ross Sea Sector oF Antarctica has been much debated, but it has generally been assumed that the modern ice sheet is as small as it has been for more than 100,000 years 15 (Conway et al., 1999; Lee et al., 2017; Lowry et al., 2019; McKay et al., 2016; Scherer et al., 1998). Recent findings suggest that the West Antarctic Ice Sheet (WAIS) grounding line retreated beyond its current location earlier in the Holocene and subsequently re-advanced to reach its modern position (Bradley et al., 2015; Kingslake et al., 2018). Here, we further constrain the post-LGM grounding line retreat and re-advance in the Ross Sea Sector using a two-phase model of radiocarbon input and decay in subglacial sediments From six sub-ice sampling locations. -
The University of Texas at Austin • Jackson School Of
THE UNIVERSITY OF TEXAS AT AUSTIN • JACKSON SCHOOL OF GEOSCIENCES • 2014 NEWSLETTER NEWSLETTER 2014 • GEOSCIENCES OF SCHOOL JACKSON • AUSTIN AT TEXAS OF UNIVERSITY THE Ne2014wsletter Newsletter insidecover_final_outlined.indd 1 9/15/2014 4:07:08 PM CONTENTS 2 WELCOME 3 BRIEFS 18 FIELD EXPERIENCES 20 IN THE NEWS 25 AWARDS & HONORS 29 LIBRARY REPORT 30 SCIENTISTS On the cover: Jackson School of Geosciences research professor Ian Dalziel with Eugenia Sangines at Siccar Point in Scotland. See pages 32 SUMMER FIELD CAMPS 82-83 for more about the 2014 Texas Exes trip. FEATURES 36 OPENING UP Mexico deregulates its state-run oil industry. By Tracy Idell Hamilton 39 PREPPING FOR SPACE A Jackson School geologist trains astronauts for trip to space. By John Williams 42 DISSECTING A GLACIER Research helps reveal Thwaites Glacier’s role in sea level rise. By Tim Green 44 STRIKING IT BIG WITH NANOTECH Scientists unlock the potential of nanotechnology in energy. By Joshua Zaffos 46 LIFELESS WATERS Mississippi River pollution a likely contributor to Gulf dead zone. By John Williams 49 RIDE HIGH AND SEEK Lidar is giving researchers an eagle-eyed view of the land. By Joshua Zaffos 51 BACK FROM TOTTEN The Newsletter, a tradition since 1950, is Ice alters research plans. By Terry Britt published annually for friends and alumni of the Jackson School of Geosciences at the 52 GEOFORCE TURNS 10 University of Texas at Austin. Program introduces high-schoolers to geoscience. By Angela Curtis EDITOR: Anton Caputo 54 A CLASSROOM AT THE EDGE OF THE WORLD ASSOCIATE EDITOR: Melissa Weber Students and professors take a journey to the Arctic. -
I!Ij 1)11 U.S
u... I C) C) co 1 USGS 0.. science for a changing world co :::2: Prepared in cooperation with the Scott Polar Research Institute, University of Cambridge, United Kingdom Coastal-change and glaciological map of the (I) ::E Bakutis Coast area, Antarctica: 1972-2002 ;::+' ::::r ::J c:r OJ ::J By Charles Swithinbank, RichardS. Williams, Jr. , Jane G. Ferrigno, OJ"" ::J 0.. Kevin M. Foley, and Christine E. Rosanova a :;:,..... CD ~ (I) I ("') a Geologic Investigations Series Map I- 2600- F (2d ed.) OJ ~ OJ '!; :;:, OJ ::J <0 co OJ ::J a_ <0 OJ n c; · a <0 n OJ 3 OJ "'C S, ..... :;:, CD a:r OJ ""a. (I) ("') a OJ .....(I) OJ <n OJ n OJ co .....,...... ~ C) .....,0 ~ b 0 C) b C) C) T....., Landsat Multispectral Scanner (MSS) image of Ma rtin and Bea r Peninsulas and Dotson Ice Shelf, Bakutis Coast, CT> C) An tarctica. Path 6, Row 11 3, acquired 30 December 1972. ? "T1 'N 0.. co 0.. 2003 ISBN 0-607-94827-2 U.S. Department of the Interior 0 Printed on rec ycl ed paper U.S. Geological Survey 9 11~ !1~~~,11~1!1! I!IJ 1)11 U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP I-2600-F (2d ed.) U.S. GEOLOGICAL SURVEY COASTAL-CHANGE AND GLACIOLOGICAL MAP OF THE BAKUTIS COAST AREA, ANTARCTICA: 1972-2002 . By Charles Swithinbank, 1 RichardS. Williams, Jr.,2 Jane G. Ferrigno,3 Kevin M. Foley, 3 and Christine E. Rosanova4 INTRODUCTION areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+)), RADARSAT images, and other data where available, to compare Background changes over a 20- to 25- or 30-year time interval (or longer Changes in the area and volume of polar ice sheets are intri where data were available, as in the Antarctic Peninsula). -
Variability in the Mass Flux of the Ross Sea Ice Streams, Antarctica, Over the Last Millennium
Portland State University PDXScholar Geology Faculty Publications and Presentations Geology 1-1-2012 Variability in the Mass Flux of the Ross Sea Ice Streams, Antarctica, over the last Millennium Ginny Catania University of Texas at Austin Christina L. Hulbe Portland State University Howard Conway University of Washington - Seattle Campus Ted A. Scambos University of Colorado at Boulder C. F. Raymond University of Washington - Seattle Campus Follow this and additional works at: https://pdxscholar.library.pdx.edu/geology_fac Part of the Geology Commons Let us know how access to this document benefits ou.y Citation Details Catania. G. A., C.L. Hulbe, H.B. Conway, T.A. Scambos, C.F. Raymond, 2012, Variability in the mass flux of the Ross Sea ice streams, Antarctica, over the last millennium. Journal of Glaciology, 58 (210), 741-752. This Article is brought to you for free and open access. It has been accepted for inclusion in Geology Faculty Publications and Presentations by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Journal of Glaciology, Vol. 58, No. 210, 2012 doi: 10.3189/2012JoG11J219 741 Variability in the mass flux of the Ross ice streams, West Antarctica, over the last millennium Ginny CATANIA,1,2 Christina HULBE,3 Howard CONWAY,4 T.A. SCAMBOS,5 C.F. RAYMOND4 1Institute for Geophysics, University of Texas, Austin, TX, USA E-mail: [email protected] 2Department of Geology, University of Texas, Austin, TX, USA 3Department of Geology, Portland State University, Portland, OR, USA 4Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA 5National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA ABSTRACT. -
The Last Glaciation of Bear Peninsula, Central Amundsen Sea
Quaternary Science Reviews 178 (2017) 77e88 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev The last glaciation of Bear Peninsula, central Amundsen Sea Embayment of Antarctica: Constraints on timing and duration revealed by in situ cosmogenic 14Cand10Be dating * Joanne S. Johnson a, , James A. Smith a, Joerg M. Schaefer b, Nicolas E. Young b, Brent M. Goehring c, Claus-Dieter Hillenbrand a, Jennifer L. Lamp b, Robert C. Finkel d, Karsten Gohl e a British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK b Lamont-Doherty Earth Observatory, Columbia University, Route 9W, Palisades, New York NY 10964, USA c Department of Earth & Environmental Sciences, Tulane University, New Orleans, LA 70118, USA d Lawrence Livermore National Laboratory, Center for Accelerator Mass Spectrometry, 7000 East Avenue Avenue, Livermore, CA 94550-9234, USA e Alfred Wegener Institute for Polar and Marine Research, Postfach 120161, D-27515 Bremerhaven, Germany article info abstract Article history: Ice streams in the Pine Island-Thwaites region of West Antarctica currently dominate contributions to sea Received 6 April 2017 level rise from the Antarctic ice sheet. Predictions of future ice-mass loss from this area rely on physical Received in revised form models that are validated with geological constraints on past extent, thickness and timing of ice cover. 18 October 2017 However, terrestrial records of ice sheet history from the region remain sparse, resulting in significant Accepted 1 November 2017 model uncertainties. We report glacial-geological evidence for the duration and timing of the last glaciation of Hunt Bluff, in the central Amundsen Sea Embayment. -
A Submarine Wall Protecting the Amundsen Sea Intensifies Melting
The Cryosphere, 13, 2317–2324, 2019 https://doi.org/10.5194/tc-13-2317-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Brief communication: A submarine wall protecting the Amundsen Sea intensifies melting of neighboring ice shelves Özgür Gürses1, Vanessa Kolatschek1, Qiang Wang1, and Christian Bernd Rodehacke1,2 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany 2Danish Meteorological Institute, Copenhagen Ø, 2100, Denmark Correspondence: Christian B. Rodehacke ([email protected]) Received: 11 February 2019 – Discussion started: 15 March 2019 Revised: 22 July 2019 – Accepted: 14 August 2019 – Published: 6 September 2019 Abstract. Disintegration of ice shelves in the Amundsen Sea, In Antarctica, remotely sensed, modeled and paleoclima- in front of the West Antarctic Ice Sheet, has the potential tological proxy data indicate that the highest potential sea to cause sea level rise by inducing an acceleration of ice level contribution will come from the West Antarctic Ice discharge from upstream grounded ice. Moore et al. (2018) Sheet (Bamber et al., 2009; Golledge et al., 2013; Joughin proposed that using a submarine wall to block the penetra- and Alley, 2011; Pollard and DeConto, 2009; Sutter et al., tion of warm water into the subsurface cavities of these ice 2016), particularly from the Amundsen Sea sector, where shelves could reduce this risk. We use a global sea ice–ocean the progressive thinning of its ice shelves over the last model to show that a wall shielding the Amundsen Sea be- 2.5 decades has greatly enhanced rates of ice mass loss em- low 350 m depth successfully suppresses the inflow of warm anating from this sector (Pritchard et al., 2012; Rignot et al., water and reduces ice shelf melting. -
Information to Users
Variations In Ice Flow And Glaciers Over Time And Space Item Type Thesis Authors Elsberg, Daniel Harry Download date 24/09/2021 03:40:40 Link to Item http://hdl.handle.net/11122/8657 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. VARIATIONS IN ICE FLOW AND GLACIERS OVER TIME AND SPACE A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Daniel Harry Elsberg, B.S. -
Spatiotemporal Variations in the Surface Velocities of Antarctic Peninsula Glaciers
Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | The Cryosphere Discuss., 8, 5875–5910, 2014 www.the-cryosphere-discuss.net/8/5875/2014/ doi:10.5194/tcd-8-5875-2014 TCD © Author(s) 2014. CC Attribution 3.0 License. 8, 5875–5910, 2014 This discussion paper is/has been under review for the journal The Cryosphere (TC). Spatiotemporal Please refer to the corresponding final paper in TC if available. variations in the surface velocities of Spatiotemporal variations in the surface Antarctic Peninsula glaciers velocities of Antarctic Peninsula glaciers J. Chen et al. J. Chen1,2, C. Q. Ke1,2, and Z. D. Shao1,2 1Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Title Page Nanjing University, Nanjing, 210023, China Abstract Introduction 2Key Laboratory for Satellite Mapping Technology and Applications of State Administration of Surveying, Mapping and Geoinformation of China, Nanjing University, Nanjing, 210023, China Conclusions References Received: 25 October 2014 – Accepted: 2 November 2014 – Published: 25 November 2014 Tables Figures Correspondence to: C. Q. Ke ([email protected]) J I Published by Copernicus Publications on behalf of the European Geosciences Union. J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 5875 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract TCD Velocity is an important parameter for the estimation of glacier mass balance, which directly signals the response of glaciers to climate change. Antarctic ice sheet move- 8, 5875–5910, 2014 ment and the associated spatiotemporal velocity variations are of great significance to 5 global sea level rise. In this study, we estimate Antarctic Peninsula glacier velocities Spatiotemporal using the co-registration of optically sensed images and correlation (hereafter referred variations in the to as COSI-Corr) based on moderate-resolution imaging spectroradiometer Level 1B surface velocities of data (hereafter referred to as MODIS L1B).