scholarly journals Brief communication: Subglacial lake drainage beneath Isunguata Sermia, West Greenland: geomorphic and ice dynamic effects

2019 ◽  
Vol 13 (10) ◽  
pp. 2789-2796 ◽  
Author(s):  
Stephen J. Livingstone ◽  
Andrew J. Sole ◽  
Robert D. Storrar ◽  
Devin Harrison ◽  
Neil Ross ◽  
...  
Keyword(s):  
Water Bodies ◽  
Lateral Margin ◽  
Dynamic Effects ◽  
Ice Flow ◽  
West Greenland ◽  
Subglacial Lake ◽  
Ice Surface ◽  
Geophysical Investigations ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. We report three active subglacial lakes within 2 km of the lateral margin of Isunguata Sermia, West Greenland, identified by differencing time-stamped ArcticDEM strips. Each lake underwent one drainage–refill event between 2009 and 2017, with two lakes draining in < 1 month in August 2014 and August 2015. The 2015 drainage caused a ∼ 1-month down-glacier slowdown in ice flow and flooded the foreland, aggrading the proglacial channel by 8 m. The proglacial flooding confirms the ice-surface elevation anomalies as subglacial water bodies and demonstrates how their drainage can significantly modify proglacial environments. These subglacial lakes offer accessible targets for geophysical investigations and exploration.

scholarly journals Modeling Antarctic subglacial lake filling and drainage cycles

2016 ◽  
Vol 10 (4) ◽  
pp. 1381-1393 ◽  
Author(s):  
Christine F. Dow ◽  
Mauro A. Werder ◽  
Sophie Nowicki ◽  
Ryan T. Walker
Keyword(s):  
Internal Controls ◽  
Water Volume ◽  
Lake Basin ◽  
Subglacial Lake ◽  
Subglacial Environment ◽  
Ice Surface ◽  
Ice Stream ◽  
Slow Moving ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

scholarly journals Investigating the stability of subglacial lakes with a full Stokes ice-sheet model

2008 ◽  
Vol 54 (185) ◽  
pp. 353-361 ◽  
Author(s):  
Frank Pattyn
Keyword(s):  
Ice Sheet ◽  
Drainage System ◽  
Potential Gradient ◽  
Surface Slope ◽  
Ice Flow ◽  
Subglacial Lake ◽  
Lake Drainage ◽  
Subglacial Lakes ◽  
The Impact ◽  
Subglacial Drainage

AbstractDespite the large amount of subglacial lakes present underneath the East Antarctic ice sheet and the melt processes involved, the hydrology beneath the ice sheet is poorly understood. Changes in subglacial potential gradients may lead to subglacial lake outbursts, discharging excess water through a subglacial drainage system underneath the ice sheet. Such processes can eventually lead to an increase in ice flow. In this paper, a full Stokes numerical ice-sheet model was employed which takes into account the ice flow over subglacial water bodies in hydrostatic equilibrium with the overlying ice. Sensitivity experiments were carried out for small perturbations in ice flow and basal melt rate as a function of ice thickness, general surface slope, ice viscosity and lake size, in order to investigate their influence on the subglacial potential gradient and the impact on subglacial lake drainage. Experiments clearly demonstrate that small changes in surface slope are sufficient to start and sustain episodic subglacial drainage events. Lake drainage can therefore be regarded as a common feature of the subglacial hydrological system and may influence, to a large extent, the present and future behavior of large ice sheets.

scholarly journals Modeling Antarctic subglacial lake filling and drainage cycles

2015 ◽  
Vol 9 (6) ◽  
pp. 6545-6579
Author(s):  
C. F. Dow ◽  
M. A. Werder ◽  
S. Nowicki ◽  
R. T. Walker
Keyword(s):  
High Water ◽  
Water Volume ◽  
Lake Basin ◽  
Subglacial Lake ◽  
Subglacial Environment ◽  
Ice Surface ◽  
Ice Stream ◽  
Drainage Channels ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to determine internal controls on the filling and drainage of subglacial lakes and their impact on ice stream dynamics. Our model outputs suggest that the highly constricted subglacial environment of the ice stream, combined with relatively high rates of water flow funneled from large catchments, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water through the ice stream drives lake growth. As the water body builds up, it too steepens the hydraulic gradient and allows greater flux out of the overdeepened lake basin. Eventually this flux is large enough to create channels that cause the lake to drain. Due to the presence of the channels, the drainage of the lake causes high water pressures around 50 km downstream of the lake rather than immediately in the vicinity of the overdeepening. Following lake drainage, channels again shut down. Lake drainage depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

scholarly journals Ice-dammed lake drainage in west Greenland: Drainage pattern and implications on ice flow and bedrock motion

2017 ◽  
Vol 44 (14) ◽  
pp. 7320-7327 ◽  
Author(s):  
Kristian K. Kjeldsen ◽  
Shfaqat A. Khan ◽  
Anders A. Bjørk ◽  
Karina Nielsen ◽  
Jeremie Mouginot
Keyword(s):  
Drainage Pattern ◽  
Ice Flow ◽  
West Greenland ◽  
Dammed Lake ◽  
Lake Drainage

scholarly journals Filling and drainage of a subglacial lake beneath the Flade Isblink ice cap, northeast Greenland

2022 ◽  
Author(s):  
Qi Liang ◽  
Wanxin Xiao ◽  
Ian Howat ◽  
Xiao Cheng ◽  
Fengming Hui ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Aquifer Storage ◽  
Subglacial Lake ◽  
Ice Cap ◽  
Lake Volume ◽  
Basin Surface ◽  
Multi Temporal ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. The generation, transport, storage and drainage of meltwater beneath the ice sheet play important roles in the Greenland ice sheet (GrIS) system. Active subglacial lakes, common features in Antarctica, have recently been detected beneath GrIS and may impact ice sheet hydrology. Despite their potential importance, few repeat subglacial lake filling and drainage events have been identified under Greenland Ice Sheet. Here we examine the surface elevation change of a collapse basin at the Flade Isblink ice cap, northeast Greenland, which formed due to sudden subglacial lake drainage in 2011. We estimate the subglacial lake volume evolution using multi-temporal ArcticDEM data and ICESat-2 altimetry data acquired between 2012 and 2021. Our long-term observations show that the subglacial lake was continuously filled by surface meltwater, with basin surface rising by up to 55 m during 2012–2021 and we estimate 138.2 × 106 m3 of meltwater was transported into the subglacial lake between 2012 and 2017. A second rapid drainage event occurred in late August 2019, which induced an abrupt ice dynamic response. Comparison between the two drainage events shows that the 2019 drainage released much less water than the 2011 event. We conclude that multiple factors, e.g., the volume of water stored in the subglacial lake and bedrock relief, regulate the episodic filling and drainage of the lake. By comparing the surface meltwater production and the subglacial lake volume change, we find only ~64 % of the surface meltwater successfully descended to the bed, suggesting potential processes such as meltwater refreezing and firn aquifer storage, need to be further quantified.

scholarly journals Lakes and subglacial hydrological networks around Dome C, East Antarctica

2003 ◽  
Vol 37 ◽  
pp. 252-256 ◽  
Author(s):  
Frédérique Rémy ◽  
Laurent Testut ◽  
Benoît Legrésy ◽  
Alessandro Forieri ◽  
Cesido Bianchi ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Flow Regime ◽  
Flow Dynamics ◽  
Ice Flow ◽  
Subglacial Lake ◽  
Radio Echo Sounding ◽  
Fine Structures ◽  
Satellite Radar ◽  
Subglacial Lakes ◽  
Satellite Radar Altimetry

AbstractPrecise topography from European Remote-sensing Satellite radar altimetry and high density of airborne radio-echo sounding in the area surrounding Dome C, Antarctica, show a link between surface features and subglacial lakes. In this paper, we extend the study to fine structures by computing a curvature-based coefficient (cy) related to surface undulations. These coefficient variations reveal many surface undulations, and some elongated features of this parameter seem to link known subglacial lakes. A population of high values of this coefficient, assumed to correspond to transitions between sliding and non-sliding flow regime, strengthen the appearance of a network which would link most of the lakes in the area. The existence of such a network impacts on ice-flow dynamics and on subglacial-lake studies.

scholarly journals The influence of a model subglacial lake on ice dynamics and internal layering

2016 ◽  
Vol 10 (2) ◽  
pp. 751-760 ◽  
Author(s):  
Eythor Gudlaugsson ◽  
Angelika Humbert ◽  
Thomas Kleiner ◽  
Jack Kohler ◽  
Karin Andreassen
Keyword(s):  
Transition Zone ◽  
Deformation Energy ◽  
Internal Layers ◽  
Ice Dynamics ◽  
Subglacial Lake ◽  
Ice Surface ◽  
Ice Flows ◽  
Rapid Transition ◽  
Subglacial Lakes ◽  
Deformational Energy

Abstract. As ice flows over a subglacial lake, the drop in bed resistance leads to an increase in ice velocities and a draw down of isochrones and cold ice. The ice surface flattens as it adjusts to the lack of resisting forces at the base. The rapid transition in velocity induces changes in ice viscosity and releases deformation energy that can raise the temperature locally. Recent studies of Antarctic subglacial lakes indicate that many lakes experience very fast and possibly episodic drainage, during which the lake size is rapidly reduced as water flows out. Questions that arise are what effect this would have on internal layers within the ice and whether such past drainage events could be inferred from isochrone structures downstream. Here, we study the effect of a subglacial lake on ice dynamics as well as the influence that such short timescale drainage would have on the internal layers of the ice. To this end, we use a full Stokes, polythermal ice flow model. An enthalpy-gradient method is used to account for the evolution of temperature and water content within the ice. We find that a rapid transition between slow-moving ice outside the lake, and full sliding over the lake, can release considerable amounts of deformational energy, with the potential to form a temperate layer at depth in the transition zone. In addition, we provide an explanation for a characteristic surface feature commonly seen at the edges of subglacial lakes, a hummocky surface depression in the transition zone between little to full sliding. We also conclude that rapid changes in the horizontal extent of subglacial lakes and slippery patches, compared to the average ice column velocity, can create a traveling wave at depth within the isochrone structure that transfers downstream with the advection of ice, thus indicating the possibility of detecting past drainage events with ice penetrating radar.

Global synthesis of subglacial lakes and their changing role in a warming climate

2021 ◽  
Author(s):  
Stephen Livingstone ◽  
Helgi Björnsson ◽  
Jade Bowling ◽  
Winnie Chu ◽  
Christine Dow ◽  
...  
Keyword(s):  
Global Perspective ◽  
Ice Flow ◽  
Global Database ◽  
Ice Caps ◽  
Subglacial Lake ◽  
Biogeochemical Fluxes ◽  
Lake Formation ◽  
Subglacial Lakes ◽  
Warming World ◽  
Lake Characteristics

&lt;p&gt;Subglacial lakes provide habitats for life and can modulate ice flow, basal hydrology, biogeochemical fluxes and geomorphic activity. They have been identified widely beneath the ice sheets of Antarctica and Greenland, and detected beneath the ice caps on Devon Island and Iceland, and beneath small valley glaciers. Past investigations focussed on lakes beneath individual ice masses. A scientific synthesis of different lake populations has not been made, so a unified understanding of the mechanisms controlling subglacial lake formation, dynamics, and interaction with other parts of the Earth system is lacking. Here, we integrate existing, often disparate data into a global database of subglacial lakes, enabling subglacial lake characteristics and dynamics to be classified. We use this assessment to evaluate how subglacial lakes shape microbial ecosystems and influence ice flow, subglacial drainage, sediment transport and biogeochemical fluxes. Through our global perspective, we examine how subglacial lake characteristics and function depend on the hydrologic, dynamic and mass balance regime of the ice mass beneath which they are located. By applying this synoptic understanding and perspective, we propose a conceptual model for how subglacial lakes and their impacts on the broader environment will change in a warming world.&amp;#160;&lt;/p&gt;

scholarly journals Detecting and Searching for subglacial lakes through airborne radio-echo sounding in Princess Elizabeth Land (PEL), Antarctica

2020 ◽  
Vol 163 ◽  
pp. 04002
Author(s):  
Xiangbin Cui ◽  
Shinan Lang ◽  
Jingxue Guo ◽  
Bo Sun
Keyword(s):  
Remote Sensing ◽  
Ice Sheet ◽  
Extreme Environment ◽  
Ice Flow ◽  
Preliminary Results ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Radio Echo Sounding ◽  
Subglacial Lakes ◽  
Echo Sounding

Over 400 subglacial lakes were discovered in Antarctica through radio-echo sounding (RES) method and remote sensing. Subglacial lakes have significance in lubricating ice-bedrock interface and enhancing ice flow. Moreover, ancient lives may exist in the extreme environment. Since 2015, the “Snow Eagle 601” BT-67 airborne platform has been deployed and applied to map ice sheet and bedrock of Princess Elizabeth Land. One of great motivations of airborne surveys is to detect and search for subglacial lakes in the region. In this paper, we provided preliminary results of RES over both old and new discovered lakes, including Lake Vostok, a potential second large subglacial lake and other lakes beneath interior of the ice sheet in Antarctica.

scholarly journals Basal icequakes during changing subglacial water pressures beneath Gornergletscher, Switzerland

2008 ◽  
Vol 54 (186) ◽  
pp. 511-521 ◽  
Author(s):  
Fabian Walter ◽  
Nicholas Deichmann ◽  
Martin Funk
Keyword(s):  
Seismic Activity ◽  
Water Pressure ◽  
Gps Measurements ◽  
Glacier Surface ◽  
Ice Flow ◽  
Dense Networks ◽  
Ice Surface ◽  
Hydrological System ◽  
Lake Drainage ◽  
The Impact

AbstractUsing dense networks of three-component seismometers installed in direct contact with the ice, the seismic activity of Gornergletscher, Switzerland, was investigated during the summers of 2004 and 2006, as subglacial water pressures varied drastically. These pressure variations are due to the diurnal cycle of meltwater input as well as the subglacial drainage of Gornersee, a nearby marginal ice-dammed lake. Up to several thousand seismic signals per day were recorded. Whereas most icequakes are due to surface crevasse openings, about 200 events have been reliably located close to the glacier bed. These basal events tend to occur in clusters and have signals with impulsive first arrivals. At the same time, basal water pressures and ice-surface velocities were measured to capture the impact of the lake drainage on the subglacial hydrological system and the ice-flow dynamics. Contrary to our expectations, we did not observe an increase of basal icequake activity as the lake emptied, thereby raising the subglacial water pressures close to the flotation level for several days. In fact, the basal icequakes were usually recorded during the morning hours, when the basal water pressure was either low or decreasing. During the high-pressure period caused by the drainage of the lake, no basal icequakes were observed. Furthermore, GPS measurements showed that the glacier surface was lowering during the basal seismic activity. These observations lead us to conclude that such icequakes are connected to the diurnal variation in glacier sliding across the glacier bed.

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