DOCSLIB.ORG

Measurement of Ice Flow Velocities from GPS Positions Logged by Short-Period Seismographs in East Antarctica Lei FU1,2,3, Jingxue GUO4 & Xiaofei CHEN1,2,3*

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measurement of Ice Flow Velocities from GPS Positions Logged by Short-Period Seismographs in East Antarctica Lei FU1,2,3, Jingxue GUO4 & Xiaofei CHEN1,2,3* SCIENCE CHINA Earth Sciences •RESEARCH PAPER• August 2021 Vol.64 No.8: 1381–1389 https://doi.org/10.1007/s11430-021-9765-6 Measurement of ice flow velocities from GPS positions logged by short-period seismographs in East Antarctica Lei FU1,2,3, Jingxue GUO4 & Xiaofei CHEN1,2,3* 1 Shenzhen Key Laboratory of Deep Offshore Oil and Gas Exploration Technology, Southern University of Science and Technology, Shenzhen 518055, China; 2 Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China; 3 Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China; 4 Key Laboratory for Polar Science, MNR, Polar Research Institute of China, Shanghai 200136, China Received January 21, 2021; revised March 8, 2021; accepted March 30, 2021; published online July 8, 2021 Abstract The ice flow velocity is a basic feature of glaciers and ice sheets. Measuring ice flow velocities is very important for estimating the mass balance of ice sheets in the Arctic and Antarctic. Traditional methods for measuring ice flow velocity include the use of stakes, snow pits and on-site geodetic GPS and remote sensing measurement methods. Geodetic GPS measurements have high accuracy, but geodetic GPS monitoring points only sparsely cover the Antarctic ice sheets. Moreover, the resolution and accuracy of ice flow velocities based on remote sensing measurements are low. Although the accuracy of the location data recorded by the navigation-grade GPS receivers embedded in short-period seismographs is not as good as that of geodetic GPS, the ice flow velocity can be accurately measured by these navigation-grade GPS data collected over a sufficiently long period. In this paper, navigation-grade GPS location data obtained by passive seismic observations during the 36th Chinese National Antarctic Research Expedition were used to accurately track the movement characteristics of the ice sheet in the Larsemann Hills of East Antarctica and the Taishan Station area. The results showed that the ice sheet in the two study areas is basically moving northwestward with an average ice flow velocity of approximately 1 m mon−1. The results in the Taishan Station area are basically consistent with the geodetic GPS results, indicating that it is feasible to use the embedded GPS location data from short- period seismographs to track the movement characteristics of ice sheets. The ice flow characteristics in the Larsemann Hills are more complex. The measured ice flow velocities in the Larsemann Hills with a resolution of 200 m help to understand its characteristics. In summary, the ice flow velocities derived from GPS location data are of great significance for studying ice sheet dynamics and glacier mass balance and for evaluating the systematic errors caused by ice sheet movements in seismic imaging. Keywords Short-period seismograph, Antarctic ice sheet, Ice flow velocity, GPS Citation: Fu L, Guo J, Chen X. 2021. Measurement of ice flow velocities from GPS positions logged by short-period seismographs in East Antarctica. Science China Earth Sciences, 64(8): 1381–1389, https://doi.org/10.1007/s11430-021-9765-6 1. Introduction ocean (Fettweis et al., 2017) have increased significantly, and the cloud cover around Greenland (Hofer et al., 2017) Global warming is accelerating the mass loss of the Arctic decreases in summer. These changes have led to surface and Antarctic ice sheets (Oppenheimer, 1998; Chylek et al., runoff (Trusel et al., 2018), the formation and drainage of 2004; Hanna et al., 2005, 2008). In recent decades, the lakes on glaciers (Leeson et al., 2015; Palmer et al., 2015), temperatures of the air (Straneo and Heimbach, 2013) and iceberg collapse (Nick et al., 2012), and glacier retreat (Joughin et al., 2008). Holland et al. (2008) studied the at- mospheric circulation over the North Atlantic and the * Corresponding author: (email: [email protected]). © Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2021 earth.scichina.com link.springer.com 1382 Fu L, et al. Sci China Earth Sci August (2021) Vol.64 No.8 changes in the Jakobshavn Glacier in Greenland and showed During the International Trans-Antarctic Scientific Expedi- that the acceleration of its mass loss was triggered by an tion (ITASE), China conducted 7 ground GPS resurveys increase in the temperature of the subsurface ocean on the from Zhongshan Station to the Dome-A section and carried west coast. Greenland, the Antarctic Peninsula, and parts of out high-precision GPS measurements by the observation West Antarctica are experiencing a moderate mass loss data of the third resurvey phase. Static positioning revealed (approximately 1 mm yr−1 equivalent of sea level rise) that the GPS points along the survey line are moving toward (Hanna et al., 2013); among them, Greenland’s ice loss ac- the northwest (the edge of the ice sheet) at a velocity of counts for the main contributors to global sea level rise. 8–24 m yr−1. Moreover, the closer the points are to the edge Model predictions indicate that in the general trend of cli- of the ice sheet, the faster the velocity, with the maximum mate warming, the mass loss in Greenland will continue reaching 100 m yr−1; at the same time, the flow of the ice (Pattyn et al., 2018). Shepherd et al. (2018) combined sa- sheet is causing a vertical subsidence rate of 0.2 to 1 m yr−1 tellite observations of volume, flow, and gravity changes (Wang et al., 2001). Zhang et al. (2008) used 19 repeated with an ice sheet surface mass balance model and showed GPS observations from Zhongshan Station to the Dome-A that the Antarctic ice sheet lost 27,200±13,900 billion tons section from 1996 to 2006 and calculated that the ice flow between 1992 and 2017, which is equivalent to an average velocity on the section gradually increases from inland to the increase of 7.6±3.9 mm in sea level. coast. The ice flow velocity in Dome-A is less than The ice flow velocity is a basic feature of glaciers and ice 10 m yr−1, while the ice flow velocity in the ice plateau is sheets: it characterizes the rate of ice transport from inland to 8–24 m yr−1, and in some local areas, the ice flow velocity coastal areas, reveals the locations of ice transport channels, reaches 98.2 m yr−1. Furthermore, the direction of ice flow is and reveals how ice blocks evolve over time (Rignot et al., roughly perpendicular to the contour of the ice sheet surface 2011). Measuring ice flow velocity is very important for elevation, mainly directed towards the Lambert Glacier Ba- estimating the mass balance of ice sheets in the Arctic and sin. Antarctic. Traditional ice flow velocity determination However, ground stake and GPS measurements can obtain methods include field in situ and remote sensing measure- only discrete observations in a local area and cannot obtain ments. Field in situ measurements usually utilize stakes, large-area glacier velocity fields; hence, remote sensing snow pits and geodetic Global Positioning System (GPS) measurement methods based on optical or microwave remote data. Dorrer et al. (1969) studied the changes in the ice sheet sensing provide a new way to obtain the entire Antarctic ice flow velocity field by using 103 stakes on a 910-km survey sheet flow velocity field. Remote sensing measurements line across the Ross Ice Shelf in Antarctica. The results mainly use image feature tracking and correlation calculation showed that the rate of separation between the McMurdo Ice principles to calculate the flow velocities of glaciers by Shelf and Ross Ice Shelf is increasing, and almost parallel feature matching (Scambos et al., 1992; Frezzotti et al., movement occurs in the middle of the ice shelf. During the 1998; Chen, 2016). Heid and Kääb (2012) compared and second (1985/1986) and third (1986/1987) Chinese Antarctic analyzed six different feature matching algorithms for scientific expeditions, Xu et al. (1988) set up six glacier Landsat optical images of five glaciers around the world and movement monitoring points using stakes on the Nelson considered that the cross-correlation (CCF-O) and phase Island Glacier in the Antarctic Peninsula and, combined with correlation (COSI-CORR) are two of the most effective optical theodolites, measured the geodetic position and ele- matching methods for global glacier velocity monitoring. vation of each point; they concluded that the glacier is Nevertheless, optical remote sensing is susceptible to the flowing toward the sea at a velocity of 14.6 m yr−1. Mea- constraints of polar night, solar radiation, clouds and fog, surements with stakes have the advantages of simple op- image oversaturation, and matching algorithms; moreover, eration and a low measurement failure rate. However, the its accuracy is relatively low. In contrast, synthetic aperture time interval between repeating measurements is long, and radar (SAR) adopts an active microwave imaging mode that this approach requires considerable logistical support. In can realize all-weather ground observations. Consequently, contrast, GPS measurement technology has the advantages SAR is important for extracting glacier flow velocities and is of acquiring omnidirectional data under all weather condi- the main method employed to estimate glacier velocities at tions with low cost, high efficiency, high precision, etc. present. Goldstein et al. (1993) first estimated the glacier Hence, GPS techniques can be very convenient for the rapid surface velocity of the Antarctic ice sheet based on the co- measurement and real-time monitoring of glacier surface herence of interferometric SAR (InSAR) data. Pattyn and velocities in the Antarctic (Chen, 2016). Manson et al. Derauw (2002) calculated the surface velocity field of the (2000) collected 73 geodetic GPS points along the 2500-m Shirase Glacier by matching the small image cores of two contour line of the Lambert Glacier Basin from 1988 to 1995 complex SAR images; the glacier in the downstream part of and showed that the ice flow velocity at the exit of the glacier the Shirase Basin is close to equilibrium, showing a slight along the GPS point route varies from 0.5 to 63 m yr−1.
Load more

Recommended publications
  • Improved Estimation of the Mass Balance of Glaciers Draining Into the Amundsen Sea Sector of West Antarctica from the CECS/NASA 2002 Campaign
    Annals of Glaciology 39 2004 231 Improved estimation of the mass balance of glaciers draining into the Amundsen Sea sector of West Antarctica from the CECS/NASA 2002 campaign Eric RIGNOT,1 Robert H. THOMAS,2 Pannir KANAGARATNAM,3 Gino CASASSA,4 Earl FREDERICK,5 Sivaprasad GOGINENI,3 William KRABILL,5 Andre`s RIVERA,4 Robert RUSSELL,5 John SONNTAG,5 Robert SWIFT,5 James YUNGEL5 1Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA E-mail: [email protected] 2EG&G Services, NASA Wallops Flight Facility, Building N-159, Wallops Island, VA 23337, USA 3The University of Kansas, 2291 Irving Hill Road, Lawrence, KS 66045-2969, USA 4Centro de Estudios Cientifı´cos, Avenida Arturo Prat 514, Casilla 1469, Valdivia, Chile 5NASA Wallops Flight Facility, Wallops Island, VA 23337, USA ABSTRACT. In November–December 2002, a joint airborne experiment by Centro de Estudios Cientifı´cos and NASA flew over the Antarctic ice sheet to collect laser altimetry and radio-echo sounding data over glaciers flowing into the Amundsen Sea. A P-3 aircraft on loan from the Chilean Navy made four flights over Pine Island, Thwaites, Pope, Smith and Kohler glaciers, with each flight yielding 1.5–2 hours of data. The thickness measurements reveal that these glaciers flow into deep troughs, which extend far inland, implying a high potential for rapid retreat. Interferometric synthetic aperture radar data (InSAR) and satellite altimetry data from the European Remote-sensing Satellites (ERS-1/-2) show rapid grounding-line retreat and ice thinning of these glaciers.
    [Show full text]
  • 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).
    [Show full text]
  • First Exposure Ages from the Amundsen Sea Embayment, West Antarctica: the Late Quaternary Context for Recent Thinning of Pine Island, Smith, and Pope Glaciers
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Electronic Publication Information Center First exposure ages from the Amundsen Sea Embayment, West Antarctica: The Late Quaternary context for recent thinning of Pine Island, Smith, and Pope Glaciers Joanne S. Johnson British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Michael J. Bentley Department of Geography, Durham University, South Road, Durham DH1 3LE, UK and British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Karsten Gohl Alfred-Wegener-Institut für Polar- und Meeresforschung, Postfach 120161, D-27515 Bremerhaven, Germany ABSTRACT Dramatic changes (acceleration, thinning, and grounding-line retreat of major ice streams) in the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS) have been observed dur- ing the past two decades, but the millennial-scale context for these changes is not yet known. We present the fi rst surface exposure ages recording thinning of Pine Island, Smith, and Pope Glaciers, which all drain into the Amundsen Sea. From these we infer progressive thinning of Pine Island Glacier at an average rate of 3.8 ± 0.3 cm yr–1 for at least the past 4.7 k.y., and of Smith and Pope Glaciers at 2.3 ± 0.2 cm yr–1 over the past 14.5 k.y. These rates are more than an order of magnitude lower than the ~1.6 m yr–1 recorded by satellite altimetry for Pine Island Glacier in the period 1992–1996. Similarly low long-term rates (2.5–9 cm yr–1 since 10 ka) have been reported farther west in the Ford Ranges, Marie Byrd Land, but in that area, the same rates of thinning continue to the present day.
    [Show full text]
  • 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.
    [Show full text]
  • Grounding Line Retreat of Pope, Smith, and Kohler Glaciers, West
    Geophysical Research Letters RESEARCH LETTER Grounding line retreat of Pope, Smith, and Kohler Glaciers, 10.1002/2016GL069287 West Antarctica, measured with Sentinel-1a radar Key Points: interferometry data • Sentinel-1 is a breakthrough mission for systematic, widespread, 1 1 1,2 1 2 continued, grounding line mapping B. Scheuchl , J. Mouginot , E. Rignot , M. Morlighem , and A. Khazendar in Antarctica • Pope, Smith, and Kohler Glaciers 1Department of Earth System Science, University of California, Irvine, CA, USA, 2Jet Propulsion Laboratory, California are undergoing major changes. Institute of Technology, Pasadena, California, USA The Grounding line of Smith Glacier continues to retreat at 2 km/yr • Crosson and Dotson Ice Shelves lost many pinning points, which Abstract We employ Sentinel-1a C band satellite radar interferometry data in Terrain Observation with significantly threatens their stability Progressive Scans mode to map the grounding line and ice velocity of Pope, Smith, and Kohler glaciers, in in years to come West Antarctica, for the years 2014–2016 and compare the results with those obtained using Earth Remote Sensing Satellites (ERS-1/2) in 1992, 1996, and 2011. We observe an ongoing, rapid grounding line retreat Supporting Information: of Smith at 2 km/yr (40 km since 1996), an 11 km retreat of Pope (0.5 km/yr), and a 2 km readvance of • Supporting Information S1 Kohler since 2011. The variability in glacier retreat is consistent with the distribution of basal slopes, i.e., fast along retrograde beds and slow along prograde beds. We find that several pinning points holding Correspondence to: Dotson and Crosson ice shelves disappeared since 1996 due to ice shelf thinning, which signal the ongoing B.
    [Show full text]
  • In This Issue
    October 1997 Volume XXXII—Number 2 In this issue... Interim head of the Office of Polar Programs appointed Highlights of the 1997–1998 research season Sea-ice conditions force Cape Roberts drill team to withdraw early Teachers at the Poles U.S. Antarctic Program news RADARSAT: Making a digital mosaic of Antarctica Science notebook: News from For the first time in 160 days, the sun begins to rise over McMurdo Station, Antarctica and beyond Antarctica, on 19 August 1997. Though austral spring is still a month away, the sun's return means resumption of flights to and from the base—and the end of Current Antarctic Literature high- isolation for the 154 Americans who spent the winter at the station. Within days lights of the sunrise, 60 new staff members as well as fresh food, newspapers, and mail were delivered to McMurdo. The rising sun also marks the beginning of a 1997–1998 austral summer field new field season on the southernmost continent. season begins early Glaciological delineation of the dynamic coastline of Antarctica The National Science Foundation (NSF) provides awards for research and edu- Antarctica and sea-level change cation in the sciences and engineering. The awardee is wholly responsible for the conduct of such research and preparation of the results for publication. The Foundation awards of funds for Foundation, therefore, does not assume responsibility for the research findings antarctic projects, 1 October or their interpretation. 1996 through 31 January 1997 The Foundation welcomes proposals from all qualified scientists and engi- neers and strongly encourages women, minorities, and persons with disabili- ties to compete fully in any of the research- and education-related programs described here.
    [Show full text]
  • Widespread, Rapid Grounding Line Retreat of Pine Island, Thwaites, Smith, and Kohler Glaciers, West Antarctica, from 1992 To
    GeophysicalResearchLetters RESEARCH LETTER Widespread, rapid grounding line retreat of Pine Island, 10.1002/2014GL060140 Thwaites, Smith, and Kohler glaciers, West Antarctica, Key Points: from 1992 to 2011 • Fast grounding line retreat of the 1,2 1 1 2 1 entire Amundsen Sea sector of E. Rignot , J. Mouginot , M. Morlighem , H. Seroussi , and B. Scheuchl West Antarctica 1 2 • Observations are a signature of Department of Earth System Science, University of California, Irvine, California, USA, Jet Propulsion Laboratory, a marine ice sheet instability California Institute of Technology, Pasadena, California, USA in Antarctica • This sector of Antarctica will remain the largest contributor to sea Abstract We measure the grounding line retreat of glaciers draining the Amundsen Sea sector of level rise West Antarctica using Earth Remote Sensing (ERS-1/2) satellite radar interferometry from 1992 to 2011. Pine Island Glacier retreated 31 km at its center, with most retreat in 2005–2009 when the glacier ungrounded Supporting Information: from its ice plain. Thwaites Glacier retreated 14 km along its fast flow core and 1 to 9 km along the sides. • Readme • Figure S1 Haynes Glacier retreated 10 km along its flanks. Smith/Kohler glaciers retreated the most, 35 km along its ice • Figure S2–S6 plain, and its ice shelf pinning points are vanishing. These rapid retreats proceed along regions of retrograde • Figure S7 bed elevation mapped at a high spatial resolution using a mass conservation technique that removes • Figure S8 • Figure S9 residual ambiguities from prior mappings. Upstream of the 2011 grounding line positions, we find no major • Figure S10 bed obstacle that would prevent the glaciers from further retreat and draw down the entire basin.
    [Show full text]
  • Accelerated Glacier Melting in West Antar Melting in West Antarctica
    News date: 25h October, 2016 compiled by Dr. Alvarinho J. Luis Accelerated glacier melting in West Antarctica documented Study findings will help improve predictions about global sea level rise Summary: Two new studies have found the fastest ongoing rates of glacier retreat ever observed in West Antarctica and offer an unprecedented look at ice melting on the floating undersides of glaciers. The results highlight how the interaction between ocean conditions and the bedrock beneath a glacier can influence the frozen mass, helping scientists better predict future Antarctica ice loss and global sea level rise. Two new studies by researchers at the Univ. of California and NASA have found the fastest ongoing rates of glacier retreat ever observed in West Antarctica and offer an unprecedented look at ice melting on the floating undersides of glaciers. The results highlight how the interaction between ocean conditions and the bedrock beneath a glacier can influence the frozen mass, helping scientists better predict future Antarctica ice loss and global sea level rise. The studies examined three neighboring glaciers that are melting and retreating at different rates. The Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea embayment in West Antarctica, the part of the continent with the largest decline in ice (see Figure). The primary question is how the Amundsen Sea sector of West Antarctica will contribute to sea level rise in the future, particularly following observations of massive changes in the area over the last two decades. Using satellite data, Scientists continue to measure the evolution of the grounding line of these glaciers, which helps determine their stability and how much mass the glacier is gaining or losing.
    [Show full text]
  • Understanding Antarctic Ice-Stream Flow Using Ice-Flow Models and Geophysical
    Understanding Antarctic ice-stream flow using ice-flow models and geophysical observations David A Lilien A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington 2019 Reading Committee: Ian Joughin, Chair Knut Christianson Benjamin Smith Program Authorized to Offer Degree: Department of Earth and Space Sciences ©Copyright 2019 David A Lilien University of Washington Abstract Understanding Antarctic ice-stream flow using ice-flow models and geophysical observations David A Lilien Chair of the supervisory committee: Dr. Ian R Joughin Department of Earth and Space Sciences Ice streams are the primary pathway by which Antarctic ice is evacuated to the ocean. Because the Antarctic ice sheets lose mass primarily through oceanic melt and calving, ice-stream dynamics exert a primary control on the mass balance of the ice sheets. Thus, changes in melt rates at the ice-sheet margins, or in accumulation in the ice-sheet interiors, affect ice-sheet mass balance on timescales modulated by the response time of the ice streams. Even abrupt changes in melt at the margins can cause ice-stream speedup and resultant thinning lasting millennia, so understanding the upstream propagation of marginally forced changes across timescales is key for understanding the ice sheets’ ongoing contribution to sea-level rise. This dissertation is comprised of three studies that use observations and models to understand changes to Antarctic ice-stream dynamics on timescales from decades to millennia. The first chapter synthesizes remotely sensed observations of Smith, Pope, and Kohler glaciers in West Antarctica to investigate the causes and extent of their retreat.
    [Show full text]
  • Article Is Available Online At
    The Cryosphere, 12, 1415–1431, 2018 https://doi.org/10.5194/tc-12-1415-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Changes in flow of Crosson and Dotson ice shelves, West Antarctica, in response to elevated melt David A. Lilien1,2, Ian Joughin1, Benjamin Smith1, and David E. Shean1,3 1Polar Science Center, Applied Physics Lab, University of Washington, Seattle, Washington, USA 2Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA 3Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA Correspondence: David A. Lilien ([email protected]) Received: 4 November 2017 – Discussion started: 2 January 2018 Revised: 21 March 2018 – Accepted: 24 March 2018 – Published: 19 April 2018 Abstract. Crosson and Dotson ice shelves are two of the 1 Introduction most rapidly changing outlets in West Antarctica, displaying both significant thinning and grounding-line retreat in recent Glaciers in the Amundsen Sea Embayment (ASE) are sus- decades. We used remotely sensed measurements of veloc- ceptible to internal instability triggered by increased ocean ity and ice geometry to investigate the processes controlling melting of buttressing ice shelves and are currently the dom- their changes in speed and grounding-line position over the inant source of sea level rise from Antarctica (Shepherd et past 20 years. We combined these observations with inverse al., 2012). Observations (Rignot et al., 2014) and modeling modeling of the viscosity of the ice shelves to understand (Favier et al., 2014; Joughin et al., 2010, 2014) suggest that how weakening of the shelves affected this speedup.
    [Show full text]
  • Widespread, Rapid Grounding Line Retreat of Pine Island, Thwaites, Smith, and Kohler Glaciers, West Antarctica, from 1992 to 2011
    UC Irvine UC Irvine Previously Published Works Title Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011 Permalink https://escholarship.org/uc/item/0wz826xt Journal Geophysical Research Letters, 41(10) ISSN 0094-8276 Authors Rignot, E Mouginot, J Morlighem, M et al. Publication Date 2014-05-28 DOI 10.1002/2014GL060140 Supplemental Material https://escholarship.org/uc/item/0wz826xt#supplemental License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California GeophysicalResearchLetters RESEARCH LETTER Widespread, rapid grounding line retreat of Pine Island, 10.1002/2014GL060140 Thwaites, Smith, and Kohler glaciers, West Antarctica, Key Points: from 1992 to 2011 • Fast grounding line retreat of the 1,2 1 1 2 1 entire Amundsen Sea sector of E. Rignot , J. Mouginot , M. Morlighem , H. Seroussi , and B. Scheuchl West Antarctica 1 2 • Observations are a signature of Department of Earth System Science, University of California, Irvine, California, USA, Jet Propulsion Laboratory, a marine ice sheet instability California Institute of Technology, Pasadena, California, USA in Antarctica • This sector of Antarctica will remain the largest contributor to sea Abstract We measure the grounding line retreat of glaciers draining the Amundsen Sea sector of level rise West Antarctica using Earth Remote Sensing (ERS-1/2) satellite radar interferometry from 1992 to 2011. Pine Island Glacier retreated 31 km at its center, with most retreat in 2005–2009 when the glacier ungrounded Supporting Information: from its ice plain. Thwaites Glacier retreated 14 km along its fast flow core and 1 to 9 km along the sides.
    [Show full text]
  • Atmosphere-Ocean-Ice Interactions in the Amundsen Sea Embayment
    PUBLICATIONS Reviews of Geophysics REVIEW ARTICLE Atmosphere-ocean-ice interactions in the Amundsen Sea 10.1002/2016RG000532 Embayment, West Antarctica Key Points: John Turner1 , Andrew Orr1 , G. Hilmar Gudmundsson1 , Adrian Jenkins1 , • The glaciers of the Amundsen Sea 2 1 1 Embayment have experienced Robert G. Bingham , Claus-Dieter Hillenbrand , and Thomas J. Bracegirdle remarkable retreat and thinning over 1 2 recent decades British Antarctic Survey, Cambridge, UK, School of GeoSciences, University of Edinburgh, Edinburgh, UK • Intrusions of Circumpolar Deep Water have contributed to the glacier thinning Abstract Over recent decades outlet glaciers of the Amundsen Sea Embayment (ASE), West Antarctica, • The complex atmosphere-ocean-ice have accelerated, thinned, and retreated, and are now contributing approximately 10% to global sea level interactions cannot be simulated in fl the current generation of models rise. All the ASE glaciers ow into ice shelves, and it is the thinning of these since the 1970s, and their ungrounding from “pinning points” that is widely held to be responsible for triggering the glaciers’ decline. These changes have been linked to the inflow of warm Circumpolar Deep Water (CPDW) onto the ASE’s continental shelf. CPDW delivery is highly variable and is closely related to the regional atmospheric Correspondence to: J. Turner, circulation. The ASE is south of the Amundsen Sea Low (ASL), which has a large variability and which has [email protected] deepened in recent decades. The ASL is influenced by the phase of the Southern Annular Mode, along with tropical climate variability. It is not currently possible to simulate such complex atmosphere-ocean-ice Citation: interactions in models, hampering prediction of future change.
    [Show full text]