scholarly journals Subglacial Lake Ellsworth: A candidate forin situexploration in West Antarctica

2004 ◽  
Vol 31 (23) ◽  
Author(s):  
Martin J. Siegert ◽  
Richard Hindmarsh ◽  
Hugh Corr ◽  
Andy Smith ◽  
John Woodward ◽  
...  
Keyword(s):  
West Antarctica ◽  
Subglacial Lake

scholarly journals Subglacial Lake CECs: Discovery and in situ survey of a privileged research site in West Antarctica

2015 ◽  
Vol 42 (10) ◽  
pp. 3944-3953 ◽  
Author(s):  
Andrés Rivera ◽  
José Uribe ◽  
Rodrigo Zamora ◽  
Jonathan Oberreuter
Keyword(s):  
West Antarctica ◽  
Subglacial Lake ◽  
Research Site

scholarly journals Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica

2020 ◽  
Vol 14 (12) ◽  
pp. 4603-4609
Author(s):  
Andrew O. Hoffman ◽  
Knut Christianson ◽  
Daniel Shapero ◽  
Benjamin E. Smith ◽  
Ian Joughin
Keyword(s):  
Time Series ◽  
Austral Winter ◽  
West Antarctica ◽  
Subglacial Lake ◽  
Satellite Velocity ◽  
Ice Velocity ◽  
Subglacial Lakes ◽  
Speed Fluctuations ◽  
Lake Systems

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 in 2017/18 and identified two new lake systems located in the western tributaries of 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 thinning and retreat of Thwaites Glacier on decadal to centennial timescales.

scholarly journals Solute sources and geochemical processes in Subglacial Lake Whillans, West Antarctica

Geology ◽  
2016 ◽  
Vol 44 (5) ◽  
pp. 347-350 ◽  
Author(s):  
Alexander B. Michaud ◽  
Mark L. Skidmore ◽  
Andrew C. Mitchell ◽  
Trista J. Vick-Majors ◽  
Carlo Barbante ◽  
...  
Keyword(s):  
Geochemical Processes ◽  
West Antarctica ◽  
Subglacial Lake ◽  
Subglacial Lake Whillans

scholarly journals Development of a clean hot water drill to access Subglacial Lake CECs, West Antarctica

2021 ◽  
pp. 1-13
Author(s):  
Keith Makinson ◽  
Paul G. D. Anker ◽  
Jonathan Garcés ◽  
David J. Goodger ◽  
Scott Polfrey ◽  
...  
Keyword(s):  
Code Of Conduct ◽  
Hot Water ◽  
West Antarctica ◽  
West Antarctic Ice Sheet ◽  
Subglacial Lake ◽  
Subglacial Environment ◽  
West Antarctic ◽  
Scientific Exploration ◽  
Additional Water ◽  
Antarctic Research

Abstract Recent drilling successes on Rutford Ice Stream in West Antarctica demonstrate the viability of hot water drilling subglacial access holes to depths >2000 m. Having techniques to access deep subglacial environments reliably paves the way for subglacial lake exploration beneath the thick central West Antarctic Ice Sheet. An ideal candidate lake, overlain by ~2650 m of ice, identified by Centro de Estudios Científicos (CECs), Chile, has led to collaboration with British Antarctic Survey to access Subglacial Lake CECs (SLCECs). To conform with the Scientific Committee on Antarctic Research code of conduct, which provides a guide to responsible scientific exploration and stewardship of these pristine systems, any access drilling must minimise all aspects of contamination and disturbance of the subglacial environment. To meet these challenges, along with thicker ice and 2000 m elevation, pumping and water treatment systems developed for the Subglacial Lake Ellsworth project, together with new diesel generators, additional water heating and longer drill hose, are currently being integrated with the BEAMISH hot water drill. A dedicated test season near SLCECs will commission the new clean hot water drill, with testing and validation of all clean operating procedures. A subsequent season will then access SLCECs cleanly.

scholarly journals Microbial Community Structure of Subglacial Lake Whillans, West Antarctica

2016 ◽  
Vol 7 ◽  
Author(s):  
Amanda M. Achberger ◽  
Brent C. Christner ◽  
Alexander B. Michaud ◽  
John C. Priscu ◽  
Mark L. Skidmore ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
West Antarctica ◽  
Subglacial Lake ◽  
Subglacial Lake Whillans

scholarly journals Basal melting over Subglacial Lake Ellsworth and its catchment: insights from englacial layering

2020 ◽  
Vol 61 (81) ◽  
pp. 198-205
Author(s):  
Neil Ross ◽  
Martin Siegert
Keyword(s):  
High Resolution ◽  
West Antarctica ◽  
Microbial Life ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Lake Outlet ◽  
Hydrological System ◽  
Subglacial Lakes ◽  
Basal Melting ◽  
Insight Into

AbstractDeep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the northwest parts of the lake as ice, flowing obliquely to the lake axis becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.

scholarly journals Connected subglacial lake activity on lower Mercer and Whillans Ice Streams, West Antarctica, 2003–2008

2009 ◽  
Vol 55 (190) ◽  
pp. 303-315 ◽  
Author(s):  
Helen Amanda Fricker ◽  
Ted Scambos
Keyword(s):  
Water Movement ◽  
Quantitative Information ◽  
West Antarctica ◽  
Ice Streams ◽  
Image Differencing ◽  
Subglacial Lake ◽  
Modis Image ◽  
Hydrologic System ◽  
Image Pairs ◽  
Subglacial Lakes

AbstractWe examine patterns of localized surface elevation change in lower Mercer and Whillans Ice Streams, West Antarctica, which we interpret as subglacial water movement through a system of lakes and channels. We detect and measure the lake activity using repeat-track laser altimetry from ICESat and image differencing from MODIS image pairs. A hydrostatic-potential map for the region shows that the lakes are distributed across three distinct hydrologic regimes. Our analysis shows that, within these regimes, some of the subglacial lakes appear to be linked, with drainage events in one reservoir causing filling and follow-on drainage in adjacent lakes. We also observe changes near ice raft ‘a’ in lower Whillans Ice Stream, and interpret them as evidence of subglacial water and other changes at the bed. The study provides quantitative information about the properties of this complex subglacial hydrologic system, and a relatively unstudied component of ice-sheet mass balance: subglacial drainage across the grounding line.

scholarly journals The "tipping" temperature within Subglacial Lake Ellsworth, West Antarctica and its implications for lake access

2011 ◽  
Vol 5 (2) ◽  
pp. 1003-1020 ◽  
Author(s):  
M. Thoma ◽  
K. Grosfeld ◽  
C. Mayer ◽  
A. M. Smith ◽  
J. Woodward ◽  
...  
Keyword(s):  
Lake Water ◽  
Critical Pressure ◽  
Empirical Equation ◽  
Time Span ◽  
West Antarctica ◽  
Subglacial Lake ◽  
The North ◽  
Temperature Regimes ◽  
Subglacial Lakes ◽  
Semi Empirical

Abstract. We present results from new geophysical data allowing 3-D modelling of the water flow within Subglacial Lake Ellsworth (SLE), West Antarctica. Our simulations indicate that this lake has a novel temperature distribution due to significantly thinner ice than other surveyed subglacial lakes. The critical pressure boundary (tipping depth), established from the semi-empirical Equation of State, defines whether the lake's flow regime is convective or stratified. It passes through SLE and separates different temperature (and flow) regimes on either side of the lake. Our results have implications for the location of proposed access holes into SLE, the choice of which will depend on scientific or operational priorities. If an understanding of subglacial lake water properties and dynamics is the priority, holes are required in a basal freezing area at the North end of the lake. This would be the preferred priority suggested by this paper, requiring temperature and salinity profiles in the water column. A location near the Southern end, where bottom currents are lowest, is optimum for detecting the record of life in the bed sediments; to minimise operational risk and maximise the time span of a bed sediment core, a location close to the middle of the lake, where the basal interface is melting and the lake bed is at its deepest, remains the best choice. Considering potential lake-water salinity and ice-density variations, we estimate the critical tipping depth, separating different temperature regimes within subglacial lakes, to be in about 2900 to 3045 m depth.

scholarly journals A subglacial hydrologic drainage hypothesis for silt sorting and deposition during retreat in Pine Island Bay

2019 ◽  
Vol 60 (80) ◽  
pp. 14-20
Author(s):  
Dustin M. Schroeder ◽  
Emma J. MacKie ◽  
Timothy T. Creyts ◽  
John B. Anderson
Keyword(s):  
Late Holocene ◽  
Water System ◽  
Small Scale ◽  
Alternative Mechanism ◽  
West Antarctica ◽  
Subglacial Lake ◽  
Sediment Deposits ◽  
Flow Speeds ◽  
Subglacial Meltwater ◽  
Continuous Deposition

AbstractLate Holocene sediment deposits in Pine Island Bay, West Antarctica, are hypothesized to be linked to intensive meltwater drainage during the retreat of the paleo-Pine Island Ice Stream after the Last Glacial Maximum. The uppermost sediment units show an abrupt transition from ice-proximal debris to a draped silt during the late Holocene, which is interpreted to coincide with rapid deglaciation. The small scale and fine sorting of the upper unit could be attributed to origins in subglacial meltwater; however the thickness and deposition rate for this unit imply punctuated- rather than continuous-deposition. This, combined with the deposit's location seaward of large, bedrock basins, has led to the interpretation of this unit as the result of subglacial lake outbursts in these basins. However, the fine-scale sorting of the silt unit is problematic for this energetic interpretation, which should mobilize and deposit a wider range of sediment sizes. To resolve this discrepancy, we present an alternative mechanism in which the silt was sorted by a distributed subglacial water system, stored in bedrock basins far inland of the grounding line, and subsequently eroded at higher flow speeds during retreat. We demonstrate that this mechanism is physically plausible given the subglacial conditions during the late Holocene. We hypothesize that similar silt units observed elsewhere in Antarctica downstream of bedrock basins could be the result of the same mechanism.

scholarly journals Subglacial controls on the flow of Institute Ice Stream, West Antarctica

2016 ◽  
Vol 57 (73) ◽  
pp. 19-24 ◽  
Author(s):  
Martin J. Siegert ◽  
Neil Ross ◽  
Jilu Li ◽  
Dustin M. Schroeder ◽  
David Rippin ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Flow Dynamics ◽  
West Antarctica ◽  
Sharp Transition ◽  
Ice Flow ◽  
Subglacial Lake ◽  
Ice Stream ◽  
Grounding Line ◽  
Sloping Bed ◽  
Basal Melting

ABSTRACTThe Institute Ice Stream (IIS) rests on a reverse-sloping bed, extending >150 km upstream into the ~1.8 km deep Robin Subglacial Basin, placing it at the threshold of marine ice-sheet instability. Understanding IIS vulnerability has focused on the effect of grounding-line melting, which is forecast to increase significantly this century. Changes to ice-flow dynamics are also important to IIS stability, yet little is known about them. Here we reveal that the trunk of the IIS occurs downstream of the intersection of three discrete subglacial features; a large ‘active’ subglacial lake, a newly-discovered sharp transition to a zone of weak basal sediments and a major tectonic rift. The border of IIS trunk flow is confined by the sediment on one side, and by a transition between basal melting and freezing at the border with the Bungenstock Ice Rise. By showing how basal sediment and water dictate present-day flow of IIS, we reveal that ice-sheet stability here is dependent on this unusual arrangement.

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