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N W Young - One of the best experts on this subject based on the ideXlab platform.
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comparison of microwave backscatter anisotropy parameterizations of the antarctic ice sheet using ascat
IEEE Transactions on Geoscience and Remote Sensing, 2014Co-Authors: Alexander D Fraser, N W Young, Neil AdamsAbstract:The C-band EUMETSAT Advanced Scatterometer (ASCAT) was launched in 2007, and provides backscatter measurements with excellent azimuth and incidence angle diversity in polar regions. C-band backscatter measurements can be used to retrieve near-surface snow/firn properties such as grain size and accumulation rate, however the Antarctic Ice Sheet (AIS) exhibits strong microwave backscatter anisotropy as a function of both incidence and azimuth angles, and this anisotropy must be well understood before such physical parameter retrieval can be accurately performed. This paper presents a detailed comparison of several different parameterizations of both the azimuth and the incidence anisotropy. Parameterizations used here result in residuals similar to the radiometric performance of ASCAT, indicating accurate characterization of the anisotropy. The analysis of these parameterizations provides an insight into the physical mechanisms taking place near the surface of the AIS. 30-day composite maps of several parameters are presented, and discussed in the context of near-surface Glaciology. This anisotropy characterization will form the basis of a technique for extraction of physical parameters of the AIS.
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evidence of a hydrological connection between the ice divide and ice sheet margin in the aurora subglacial basin east antarctica
Journal of Geophysical Research, 2012Co-Authors: A P Wright, N W Young, Duncan A Young, J L Roberts, D M Schroeder, Jonathan L Bamber, Julian A Dowdeswell, A Le M BrocqAbstract:Subglacial hydrology in East Antarctica is poorly understood, yet may be critical to the manner in which ice flows. Data from a new regional airborne geophysical survey (ICECAP) have transformed our understanding of the topography and Glaciology associated with the 287,000 km2 Aurora Subglacial Basin in East Antarctica. Using these data, in conjunction with numerical ice sheet modeling, we present a suite of analyses that demonstrate the potential of the 1000 km-long basin as a route for subglacial water drainage from the ice sheet interior to the ice sheet margin. We present results from our analysis of basal topography, bed roughness and radar power reflectance and from our modeling of ice sheet flow and basal ice temperatures. Although no clear-cut subglacial lakes are found within the Aurora Basin itself, dozens of lake-like reflectors are observed that, in conjunction with other results reported here, support the hypothesis that the basin acts as a pathway allowing discharge from subglacial lakes near the Dome C ice divide to reach the coast via the Totten Glacier.
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digital elevation models for the lambert glacier amery ice shelf system east antarctica from ers 1 satellite radar altimetry
Journal of Glaciology, 2000Co-Authors: H A Fricker, G Hyland, R Coleman, N W YoungAbstract:The Lambert Glacier-Amery Ice Shelf system is a major component of the East Antarctic ice sheet. This paper presents two digital elevation models (DEMs) that have been generated for the Lambert-Amery system from validated European Remote-sensing Satellite (ERS-1) radar altimeter waveform data. The first DEM covers the Amery Ice Shelf only, and was produced using kriging on a 1 km grid. The second is a coarser (5 km) DEM of the entire Lambert-Amcry system, generated via simple averaging procedures. The DEMs provide unprecedented surface elevation information for the Lambert-Amery system and allow new insight into the Glaciology of the region.
Martin J Siegert - One of the best experts on this subject based on the ideXlab platform.
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corrigendum to boundary conditions of an active west antarctic subglacial lake implications for storage of water beneath the ice sheet published in the cryosphere 8 15 24 2014
The Cryosphere, 2014Co-Authors: Martin J Siegert, Neil Ross, Hugh F J Corr, Benjamin Smith, T A Jordan, R Bingham, F Ferraccioli, David M Rippin, A Le M BrocqAbstract:M. J. Siegert1, N. Ross2, H. Corr3, B. Smith4, T. Jordan3, R. G. Bingham5, F. Ferraccioli3, D. M. Rippin6, and A. Le Brocq7 1Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK 2School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK 3British Antarctic Survey, Cambridge CB3 0ET, UK 4Applied Physics Lab, Polar Science Center, University of Washington, Seattle, WA 98105, USA 5School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK 6Environment Department, University of York, York YO10 5DD, UK 7Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK
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the antarctic subglacial lake vostok Glaciology biology and planetology
Eos Transactions American Geophysical Union, 2006Co-Authors: Martin J SiegertAbstract:Igor Zotikov has been involved in Antarctic glaciological research since the 1957–1958 third International Polar Year (IPY). His theoretical analyses of ice flow and heat transfer were important early contributions to our present understanding of the Antarctic Ice Sheet. These contributions were also critical to the eventual appreciation that a large body of water existed beneath the approximately 3.7-kilometer-thick ice column at Vostok Station in central East Antarctica. In his short book, titled The Antarctic Subglacial Lake Vostok: Glaciology, Biology and Planetology, Zotikov reflects on his and his colleagues' 40-year contribution to the story of Lake Vostok's discovery, and to future exploration of subglacial lake environments. While several authors have discussed the history of subglacial lake exploration, accounts have varied. Zotikov provides, in my opinion, the fullest and most balanced explanation of Antarctic subglacial lake discovery available. For this reason alone the book is of great value as a historical resource, although there are some weaknesses. Essentially, the work highlights the fascinating background to a paper by Kapitsa et al. [1996] that led to the recognition of Lake Vostok as a deep-water body capable of supporting unique microorganisms. Since this paper, several international meetings (held in Russia, France, the United Kingdom, and the United States) have been organized to plan for the exploration of subglacial lake environments. This book therefore charts the origin of an exciting and important new area of interdisciplinary science in Antarctica.
A Le M Brocq - One of the best experts on this subject based on the ideXlab platform.
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corrigendum to boundary conditions of an active west antarctic subglacial lake implications for storage of water beneath the ice sheet published in the cryosphere 8 15 24 2014
The Cryosphere, 2014Co-Authors: Martin J Siegert, Neil Ross, Hugh F J Corr, Benjamin Smith, T A Jordan, R Bingham, F Ferraccioli, David M Rippin, A Le M BrocqAbstract:M. J. Siegert1, N. Ross2, H. Corr3, B. Smith4, T. Jordan3, R. G. Bingham5, F. Ferraccioli3, D. M. Rippin6, and A. Le Brocq7 1Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK 2School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK 3British Antarctic Survey, Cambridge CB3 0ET, UK 4Applied Physics Lab, Polar Science Center, University of Washington, Seattle, WA 98105, USA 5School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK 6Environment Department, University of York, York YO10 5DD, UK 7Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK
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evidence of a hydrological connection between the ice divide and ice sheet margin in the aurora subglacial basin east antarctica
Journal of Geophysical Research, 2012Co-Authors: A P Wright, N W Young, Duncan A Young, J L Roberts, D M Schroeder, Jonathan L Bamber, Julian A Dowdeswell, A Le M BrocqAbstract:Subglacial hydrology in East Antarctica is poorly understood, yet may be critical to the manner in which ice flows. Data from a new regional airborne geophysical survey (ICECAP) have transformed our understanding of the topography and Glaciology associated with the 287,000 km2 Aurora Subglacial Basin in East Antarctica. Using these data, in conjunction with numerical ice sheet modeling, we present a suite of analyses that demonstrate the potential of the 1000 km-long basin as a route for subglacial water drainage from the ice sheet interior to the ice sheet margin. We present results from our analysis of basal topography, bed roughness and radar power reflectance and from our modeling of ice sheet flow and basal ice temperatures. Although no clear-cut subglacial lakes are found within the Aurora Basin itself, dozens of lake-like reflectors are observed that, in conjunction with other results reported here, support the hypothesis that the basin acts as a pathway allowing discharge from subglacial lakes near the Dome C ice divide to reach the coast via the Totten Glacier.
Nicholas R Golledge - One of the best experts on this subject based on the ideXlab platform.
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Glaciology and geological signature of the last glacial maximum antarctic ice sheet
Quaternary Science Reviews, 2013Co-Authors: Nicholas R Golledge, Richard H Levy, Robert M Mckay, Christopher J Fogwill, Duanne A White, Alastair G C Graham, James Smith, Clausdieter Hillenbrand, Kathy J LichtAbstract:Dynamical changes in contemporary ice sheets account for significant proportions of their current rates of mass loss, but assessing whether or not these processes are a natural part of ice-sheet evolution requires inference from palaeo-glaciological records. However, a robust mechanism for translating sparse geological data into meaningful interpretations of past glacier dynamics at the continental scale is lacking, since geological archives can be ambiguous, and often their chronology is only poorly constrained. To address this, we combine the interpretation of high-resolution Antarctic ice sheet model results with continent-wide geological evidence pertinent to the dynamical configuration of the ice sheet during the last, and possibly preceding, glacial maxima. We first focus on the thermal regime of the ice sheet, its pattern and velocity of flow, variability in likely subglacial erosion and sediment transport, and how these characteristics evolve during glacial transitions. We show that rapid basal sliding was restricted to discrete outlets that eroded and advected sediment toward and across the continental shelf primarily during the early stages of advance and retreat of the ice sheet, highlighting the need to consider time-transgressive behaviour in the interpretation of geological archives. Secondly, we present new modelling that attempts to improve the fit of our numerical model to geologically-based reconstructions in the Ross Sea. By accounting for locally-enhanced ablation in McMurdo Sound, our new simulation achieves a much closer fit to empirically-derived flow patterns than previously. Growth of the modelled Last Glacial Maximum ice sheet takes place primarily by marine ice accretion in the major embayments, as a consequence of cooler ocean temperatures and reduced sub-ice-shelf melting, and at its maximal extent represents a grounded ice volume excess above present of approximately 8.3 m sea-level equivalent. This figure thus provides an upper bound on the possible Antarctic contribution to deglacial meltwater pulses.
William B Krabill - One of the best experts on this subject based on the ideXlab platform.
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contribution to the Glaciology of northern greenland from satellite radar interferometry
Journal of Geophysical Research, 2001Co-Authors: Eric Rignot, Ian Joughin, S Gogineni, William B KrabillAbstract:Interferometric synthetic aperture radar (InSAR) data from the ERS-1 and ERS-2 satellites are used to measure the surface velocity, topography, and grounding line position of the major outlet glaciers in the northern sector of the Greenland ice sheet. The mass output of the glaciers at and above the grounding line is determined and compared with the mass input. We find that the grounding line output is approximately in balance with the input, except for the three largest glaciers for which the mass loss is 4±3 km3 ice year-1 or 11±8% of the mass input. Along the coast we detect a systematic retreat of the grounding lines between 1992 and 1996 with InSAR, which implies that the outlet glaciers are thinning. The inferred coastal thinning is too large to be explained by a few warm summers. Glacier thinning must be of dynamic origin, that is, caused by spatial and temporal changes in ice velocity. Iceberg production from the glaciers is uncharacteristically low. It accounts for only 8% of the ice discharge to the ocean. About 55% of the ice is lost through basal melting (5-8 m ice year-1 on average) from the underside of the floating glacier tongues that are in contact with warm ocean waters. Mass losses are highest in the first 10 km of floating ice, where ice reaches the greatest depths and basal melting is 3 times larger than on average. Only a small increase in basal melting would suffice to disintegrate the floating glacier tongues. Copyright 2001 by the American Geophysical Union.