Articles | Volume 15, issue 3
Research article 01 Apr 2021
Research article | 01 Apr 2021
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery
Corinne L. Benedek and Ian C. Willis
No articles found.
Rebecca Dell, Neil Arnold, Ian Willis, Alison Banwell, Andrew Williamson, Hamish Pritchard, and Andrew Orr
The Cryosphere, 14, 2313–2330,Short summary
A semi-automated method is developed from pre-existing work to track surface water bodies across Antarctic ice shelves over time, using data from Sentinel-2 and Landsat 8. This method is applied to the Nivlisen Ice Shelf for the 2016–2017 melt season. The results reveal two large linear meltwater systems, which hold 63 % of the peak total surface meltwater volume on 26 January 2017. These meltwater systems migrate towards the ice shelf front as the melt season progresses.
Lindsey I. Nicholson, Michael McCarthy, Hamish D. Pritchard, and Ian Willis
The Cryosphere, 12, 3719–3734,Short summary
Ground-penetrating radar of supraglacial debris thickness is used to study local thickness variability. Freshly emergent debris cover appears to have higher skewness and kurtosis than more mature debris covers. Accounting for debris thickness variability in ablation models can result in markedly different ice ablation than is calculated using the mean debris thickness. Slope stability modelling reveals likely locations for locally thin debris with high ablation.
Andrew G. Williamson, Alison F. Banwell, Ian C. Willis, and Neil S. Arnold
The Cryosphere, 12, 3045–3065,Short summary
A new approach is presented for automatically monitoring changes to area and volume of surface lakes on the Greenland Ice Sheet using Landsat 8 and Sentinel-2 satellite data. The dual-satellite record improves on previous work since it tracks changes to more lakes (including small ones), identifies more lake-drainage events, and has higher precision. The results also show that small lakes are important in ice-sheet hydrology as they route more surface run-off into the ice sheet than large lakes.
Related subject area
Discipline: Ice sheets | Subject: GreenlandBasal traction mainly dictated by hard-bed physics over grounded regions of GreenlandThe GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 1: Projections of the Greenland ice sheet evolution by the end of the 21st centuryThe cooling signature of basal crevasses in a hard-bedded region of the Greenland Ice SheetLast glacial ice sheet dynamics offshore NE Greenland – a case study from Store Koldewey TroughLarge and irreversible future decline of the Greenland ice sheetGrSMBMIP: intercomparison of the modelled 1980–2012 surface mass balance over the Greenland Ice SheetThe firn meltwater Retention Model Intercomparison Project (RetMIP): evaluation of nine firn models at four weather station sites on the Greenland ice sheetEvaluation of a new snow albedo scheme for the Greenland ice sheet in the Regional Atmospheric Climate Model (RACMO2)Surface velocity of the Northeast Greenland Ice Stream (NEGIS): assessment of interior velocities derived from satellite data by GPSIntercomparison of surface meltwater routing models for the Greenland ice sheet and influence on subglacial effective pressuresSensitivity of Greenland ice sheet projections to spatial resolution in higher-order simulations: the Alfred Wegener Institute (AWI) contribution to ISMIP6 Greenland using the Ice-sheet and Sea-level System Model (ISSM)Impact of updated radiative transfer scheme in RACMO2.3p3 on the surface mass and energy budget of the Greenland ice sheetThe future sea-level contribution of the Greenland ice sheet: a multi-model ensemble study of ISMIP6Present-day and future Greenland Ice Sheet precipitation frequency from CloudSat observations and the Community Earth System ModelThe added value of high resolution in estimating the surface mass balance in southern GreenlandHorizontal ice flow impacts the firn structure of Greenland's percolation zoneBrief communication: CESM2 climate forcing (1950–2014) yields realistic Greenland ice sheet surface mass balanceUnprecedented atmospheric conditions (1948–2019) drive the 2019 exceptional melting season over the Greenland ice sheetCalving event size measurements and statistics of Eqip Sermia, Greenland, from terrestrial radar interferometryBrief communication: Evaluation of the near-surface climate in ERA5 over the Greenland Ice SheetAlgal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedoRelating regional and point measurements of accumulation in southwest GreenlandSurface mass balance downscaling through elevation classes in an Earth system model: application to the Greenland ice sheetBrief communication: Subglacial lake drainage beneath Isunguata Sermia, West Greenland: geomorphic and ice dynamic effectsThe surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet's surface mass balanceSubmarine melt as a potential trigger of the North East Greenland Ice Stream margin retreat during Marine Isotope Stage 3Firn data compilation reveals widespread decrease of firn air content in western GreenlandIncreased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusionsVelocity response of Petermann Glacier, northwest Greenland, to past and future calving eventsSeasonal to decadal variability in ice discharge from the Greenland Ice SheetA new surface meltwater routing model for use on the Greenland Ice Sheet surfaceBrief communication: Impact of the recent atmospheric circulation change in summer on the future surface mass balance of the Greenland Ice SheetBrief communication: Recent changes in summer Greenland blocking captured by none of the CMIP5 modelsDynamic changes in outlet glaciers in northern Greenland from 1948 to 2015Processes influencing heat transfer in the near-surface ice of Greenland's ablation zoneSimulation of the future sea level contribution of Greenland with a new glacial system modelSeasonal mass variations show timing and magnitude of meltwater storage in the Greenland Ice SheetA constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoesGreenland Ice Mapping Project: ice flow velocity variation at sub-monthly to decadal timescalesObservations and modelling of algal growth on a snowpack in north-western GreenlandSeasonal monitoring of melt and accumulation within the deep percolation zone of the Greenland Ice Sheet and comparison with simulations of regional climate modelingBrief communication: Improved simulation of the present-day Greenland firn layer (1960–2016)Simulating ice thickness and velocity evolution of Upernavik Isstrøm 1849–2012 by forcing prescribed terminus positions in ISSM
Nathan Maier, Florent Gimbert, Fabien Gillet-Chaulet, and Adrien Gilbert
The Cryosphere, 15, 1435–1451,Short summary
In Greenland, ice motion and the surface geometry depend on the friction at the bed. We use satellite measurements and modeling to determine how ice speeds and friction are related across the ice sheet. The relationships indicate that ice flowing over bed bumps sets the friction across most of the ice sheet's on-land regions. This result helps simplify and improve our understanding of how ice motion will change in the future.
Aurélien Quiquet and Christophe Dumas
The Cryosphere, 15, 1015–1030,Short summary
We present here the GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for CMIP6 for Greenland. The project aims to quantify the ice sheet contribution to global sea level rise for the next century. We show an important spread in the simulated Greenland ice loss in the future depending on the climate forcing used. Mass loss is primarily driven by atmospheric warming, while oceanic forcing contributes to a relatively smaller uncertainty in our simulations.
Ian E. McDowell, Neil F. Humphrey, Joel T. Harper, and Toby W. Meierbachtol
The Cryosphere, 15, 897–907,Short summary
Ice temperature controls rates of internal deformation and the onset of basal sliding. To identify heat transfer mechanisms and englacial heat sources within Greenland's ablation zone, we examine a 2–3-year continuous temperature record from nine full-depth boreholes. Thermal decay after basal crevasses release heat in the near-basal ice likely produces the observed cooling. Basal crevasses in Greenland can affect the basal ice rheology and indicate a potentially complex basal hydrologic system.
Ingrid Leirvik Olsen, Tom Arne Rydningen, Matthias Forwick, Jan Sverre Laberg, and Katrine Husum
The Cryosphere, 14, 4475–4494,Short summary
We present marine geoscientific data from Store Koldewey Trough, one of the largest glacial troughs offshore NE Greenland, to reconstruct the ice drainage pathways, ice sheet extent and ice stream dynamics of this sector during the last glacial and deglaciation. The complex landform assemblage in the trough reflects a dynamic retreat with several periods of stabilization and readvances, interrupting the deglaciation. Estimates indicate that the ice front locally retreated between 80–400 m/year.
Jonathan M. Gregory, Steven E. George, and Robin S. Smith
The Cryosphere, 14, 4299–4322,Short summary
Melting of the Greenland ice sheet as a consequence of global warming could raise global-mean sea level by up to 7 m. We have studied this using a newly developed computer model. With recent climate maintained, sea level would rise by 0.5–2.5 m over many millennia due to Greenland ice loss: the warmer the climate, the greater the sea level rise. Beyond about 3.5 m it would become partially irreversible. In order to avoid this outcome, anthropogenic climate change must be reversed soon enough.
Xavier Fettweis, Stefan Hofer, Uta Krebs-Kanzow, Charles Amory, Teruo Aoki, Constantijn J. Berends, Andreas Born, Jason E. Box, Alison Delhasse, Koji Fujita, Paul Gierz, Heiko Goelzer, Edward Hanna, Akihiro Hashimoto, Philippe Huybrechts, Marie-Luise Kapsch, Michalea D. King, Christoph Kittel, Charlotte Lang, Peter L. Langen, Jan T. M. Lenaerts, Glen E. Liston, Gerrit Lohmann, Sebastian H. Mernild, Uwe Mikolajewicz, Kameswarrao Modali, Ruth H. Mottram, Masashi Niwano, Brice Noël, Jonathan C. Ryan, Amy Smith, Jan Streffing, Marco Tedesco, Willem Jan van de Berg, Michiel van den Broeke, Roderik S. W. van de Wal, Leo van Kampenhout, David Wilton, Bert Wouters, Florian Ziemen, and Tobias Zolles
The Cryosphere, 14, 3935–3958,Short summary
We evaluated simulated Greenland Ice Sheet surface mass balance from 5 kinds of models. While the most complex (but expensive to compute) models remain the best, the faster/simpler models also compare reliably with observations and have biases of the same order as the regional models. Discrepancies in the trend over 2000–2012, however, suggest that large uncertainties remain in the modelled future SMB changes as they are highly impacted by the meltwater runoff biases over the current climate.
Baptiste Vandecrux, Ruth Mottram, Peter L. Langen, Robert S. Fausto, Martin Olesen, C. Max Stevens, Vincent Verjans, Amber Leeson, Stefan Ligtenberg, Peter Kuipers Munneke, Sergey Marchenko, Ward van Pelt, Colin R. Meyer, Sebastian B. Simonsen, Achim Heilig, Samira Samimi, Shawn Marshall, Horst Machguth, Michael MacFerrin, Masashi Niwano, Olivia Miller, Clifford I. Voss, and Jason E. Box
The Cryosphere, 14, 3785–3810,Short summary
In the vast interior of the Greenland ice sheet, snow accumulates into a thick and porous layer called firn. Each summer, the firn retains part of the meltwater generated at the surface and buffers sea-level rise. In this study, we compare nine firn models traditionally used to quantify this retention at four sites and evaluate their performance against a set of in situ observations. We highlight limitations of certain model designs and give perspectives for future model development.
Christiaan T. van Dalum, Willem Jan van de Berg, Stef Lhermitte, and Michiel R. van den Broeke
The Cryosphere, 14, 3645–3662,Short summary
The reflectivity of sunlight, which is also known as albedo, is often inadequately modeled in regional climate models. Therefore, we have implemented a new snow and ice albedo scheme in the regional climate model RACMO2. In this study, we evaluate a new RACMO2 version for the Greenland ice sheet by using observations and the previous model version. RACMO2 output compares well with observations, and by including new processes we improve the ability of RACMO2 to make future climate projections.
Christine S. Hvidberg, Aslak Grinsted, Dorthe Dahl-Jensen, Shfaqat Abbas Khan, Anders Kusk, Jonas Kvist Andersen, Niklas Neckel, Anne Solgaard, Nanna B. Karlsson, Helle Astrid Kjær, and Paul Vallelonga
The Cryosphere, 14, 3487–3502,Short summary
The Northeast Greenland Ice Stream (NEGIS) extends around 600 km from its onset in the interior of Greenland to the coast. Several maps of surface velocity and topography in Greenland exist, but accuracy is limited due to the lack of validation data. Here we present results from a 5-year GPS survey in an interior section of NEGIS. We use the data to assess a list of satellite-derived ice velocity and surface elevation products and discuss the implications for the ice stream flow in the area.
Kang Yang, Aleah Sommers, Lauren C. Andrews, Laurence C. Smith, Xin Lu, Xavier Fettweis, and Manchun Li
The Cryosphere, 14, 3349–3365,Short summary
This study compares hourly supraglacial moulin discharge simulations from three surface meltwater routing models. Results show that these models are superior to simply using regional climate model runoff without routing, but different routing models, different-spatial-resolution DEMs, and parameterized seasonal evolution of supraglacial stream and river networks induce significant variability in diurnal moulin discharges and corresponding subglacial effective pressures.
Martin Rückamp, Heiko Goelzer, and Angelika Humbert
The Cryosphere, 14, 3309–3327,Short summary
Estimates of future sea-level contribution from the Greenland ice sheet have a large uncertainty based on different origins. We conduct numerical experiments to test the sensitivity of Greenland ice sheet projections to spatial resolution. Simulations with a higher resolution unveil up to 5 % more sea-level rise compared to coarser resolutions. The sensitivity depends on the magnitude of outlet glacier retreat. When no retreat is enforced, the sensitivity exhibits an inverse behaviour.
Christiaan T. van Dalum, Willem Jan van de Berg, and Michiel R. van den Broeke
The Cryosphere Discuss.,
Revised manuscript accepted for TCShort summary
Absorption of solar radiation is often limited to the surface in regional climate models. Therefore, we have implemented a new radiative transfer scheme in the model RACMO2, which allows for internal heating and improves the surface reflectivity. Here, we evaluate its impact on the surface mass and energy budget and (sub)surface temperature, by using observations and the previous model version for the Greenland ice sheet. New results match better with observations and introduces subsurface melt.
Heiko Goelzer, Sophie Nowicki, Anthony Payne, Eric Larour, Helene Seroussi, William H. Lipscomb, Jonathan Gregory, Ayako Abe-Ouchi, Andrew Shepherd, Erika Simon, Cécile Agosta, Patrick Alexander, Andy Aschwanden, Alice Barthel, Reinhard Calov, Christopher Chambers, Youngmin Choi, Joshua Cuzzone, Christophe Dumas, Tamsin Edwards, Denis Felikson, Xavier Fettweis, Nicholas R. Golledge, Ralf Greve, Angelika Humbert, Philippe Huybrechts, Sebastien Le clec'h, Victoria Lee, Gunter Leguy, Chris Little, Daniel P. Lowry, Mathieu Morlighem, Isabel Nias, Aurelien Quiquet, Martin Rückamp, Nicole-Jeanne Schlegel, Donald A. Slater, Robin S. Smith, Fiamma Straneo, Lev Tarasov, Roderik van de Wal, and Michiel van den Broeke
The Cryosphere, 14, 3071–3096,Short summary
In this paper we use a large ensemble of Greenland ice sheet models forced by six different global climate models to project ice sheet changes and sea-level rise contributions over the 21st century. The results for two different greenhouse gas concentration scenarios indicate that the Greenland ice sheet will continue to lose mass until 2100, with contributions to sea-level rise of 90 ± 50 mm and 32 ± 17 mm for the high (RCP8.5) and low (RCP2.6) scenario, respectively.
Jan T. M. Lenaerts, M. Drew Camron, Christopher R. Wyburn-Powell, and Jennifer E. Kay
The Cryosphere, 14, 2253–2265,
Willem Jan van de Berg, Erik van Meijgaard, and Lambertus H. van Ulft
The Cryosphere, 14, 1809–1827,Short summary
In times of increasing computer power, atmospheric models that estimate the surface mass balance of the Greenland can be run with increasing resolution. However, at which resolution is the error no longer determined by the lacking resolution but by model shortcomings? In this manuscript we show that for the majority of the southern part of the Greenland Ice Sheet, our study area, a model resolution of 20 km is sufficient although finer model resolutions are still beneficial.
Rosemary Leone, Joel Harper, Toby Meierbachtol, and Neil Humphrey
The Cryosphere, 14, 1703–1712,Short summary
Horizontal ice flow transports the firn layer of Greenland’s Percolation Zone as it undergoes burial by accumulation. Here we show that the firn density and temperature fields can reflect horizontal advection of the firn column across climate gradients, the magnitude of which varies around the ice sheet. Further, time series of melt features in ice cores from the percolation zone can contain a signature from ice motion that should not be conflated with that from climate change.
Brice Noël, Leonardus van Kampenhout, Willem Jan van de Berg, Jan T. M. Lenaerts, Bert Wouters, and Michiel R. van den Broeke
The Cryosphere, 14, 1425–1435,Short summary
We present a reconstruction of historical (1950–2014) surface mass balance of the Greenland ice sheet using the Community Earth System Model (CESM2; ~111 km) to force a high-resolution regional climate model (RACMO2; ~11 km), which is further refined to 1 km spatial resolution. For the first time, an Earth-system-model-based product, assimilating no observations, can reconstruct realistic historical ice sheet surface mass balance as well as the mass loss acceleration that started in the 1990s.
Marco Tedesco and Xavier Fettweis
The Cryosphere, 14, 1209–1223,Short summary
Unprecedented atmospheric conditions occurring in the summer of 2019 over Greenland promoted new record or close-to-record values of mass loss. Summer of 2019 was characterized by an exceptional persistence of anticyclonic conditions that enhanced melting.
Andrea Walter, Martin P. Lüthi, and Andreas Vieli
The Cryosphere, 14, 1051–1066,Short summary
Glacier calving plays a key role in the dynamic mass loss of ocean-terminating glaciers in Greenland. Source areas and volumes of 900 individual calving events were analysed for size and timing related to environmental forcings. We found that calving volume distribution and style vary along the calving front and are controlled by the water depth and front geometry. We suggest that in deep water both oceanic melt and subaquatic calving contribute substantially to the frontal mass loss.
Alison Delhasse, Christoph Kittel, Charles Amory, Stefan Hofer, Dirk van As, Robert S. Fausto, and Xavier Fettweis
The Cryosphere, 14, 957–965,Short summary
The ERA5 reanalysis of the ECMWF replaced the ERA-Interim in August 2019 and has never been evaluated over Greenland. The aim was to evaluate the performance of ERA5 to simulate the near-surface climate of the Greenland Ice sheet (GrIS) against ERA-Interim and regional climate models with the help of in situ observations from the PROMICE dataset. We also highlighted that polar regional climate models are still a useful tool to study the GrIS climate compared to ERA5.
Andrew J. Tedstone, Joseph M. Cook, Christopher J. Williamson, Stefan Hofer, Jenine McCutcheon, Tristram Irvine-Fynn, Thomas Gribbin, and Martyn Tranter
The Cryosphere, 14, 521–538,Short summary
Albedo describes how much light that hits a surface is reflected without being absorbed. Low-albedo ice surfaces melt more quickly. There are large differences in the albedo of bare-ice areas of the Greenland Ice Sheet. They are caused both by dark glacier algae and by the condition of the underlying ice. Changes occur over centimetres to metres, so satellites do not always detect real albedo changes. Estimates of melt made using satellite measurements therefore tend to be underestimates.
Achim Heilig, Olaf Eisen, Martin Schneebeli, Michael MacFerrin, C. Max Stevens, Baptiste Vandecrux, and Konrad Steffen
The Cryosphere, 14, 385–402,Short summary
We investigate the spatial representativeness of point observations of snow accumulation in SW Greenland. Such analyses have rarely been conducted but are necessary to link regional-scale observations from, e.g., remote-sensing data to firn cores and snow pits. The presented data reveal a low regional variability in density but snow depth can vary significantly. It is necessary to combine pits with spatial snow depth data to increase the regional representativeness of accumulation observations.
Raymond Sellevold, Leonardus van Kampenhout, Jan T. M. Lenaerts, Brice Noël, William H. Lipscomb, and Miren Vizcaino
The Cryosphere, 13, 3193–3208,Short summary
We evaluate a downscaling method to calculate ice sheet surface mass balance with global climate models, despite their coarse resolution. We compare it with high-resolution climate modeling. Despite absence of fine-scale simulation of individual energy and mass contributors, the method provides realistic vertical SMB gradients that can be used in forcing of ice sheet models, e.g., for sea level projections. Also, the climate model simulation is improved with the method implemented interactively.
Stephen J. Livingstone, Andrew J. Sole, Robert D. Storrar, Devin Harrison, Neil Ross, and Jade Bowling
The Cryosphere, 13, 2789–2796,Short summary
We report three new subglacial lakes close to the ice sheet margin of West Greenland. The lakes drained and refilled once each between 2009 and 2017, with two lakes draining in < 1 month during August 2014 and August 2015. The 2015 drainage caused a ~ 1-month down-glacier slowdown in ice flow and flooded the foreland, significantly modifying the braided river and depositing up to 8 m of sediment. These subglacial lakes offer accessible targets for future investigations and exploration.
Aku Riihelä, Michalea D. King, and Kati Anttila
The Cryosphere, 13, 2597–2614,Short summary
We used a 1982–2015 time series of satellite observations to examine changes in surface reflectivity (albedo) of the Greenland Ice Sheet. We found notable decreases in albedo over most of the ice sheet margins in July and August, particularly over the west coast and between 2000 and 2015. The results indicate that significant melt now occurs in areas 50 to 100 m higher up the ice sheet relative to the early 1980s. The albedo decrease is consistent and covarying with modelled ice sheet mass loss.
Ilaria Tabone, Alexander Robinson, Jorge Alvarez-Solas, and Marisa Montoya
The Cryosphere, 13, 1911–1923,Short summary
Recent reconstructions show that the North East Greenland Ice Stream (NEGIS) retreated away from its present-day position by 20–40 km during MIS-3. Atmospheric and external forcings were proposed as potential causes of this retreat, but the role of the ocean was not considered. Here, using a 3-D ice-sheet model, we suggest that oceanic warming is sufficient to induce a retreat of the NEGIS margin of many tens of kilometres during MIS-3, helping to explain this conundrum.
Baptiste Vandecrux, Michael MacFerrin, Horst Machguth, William T. Colgan, Dirk van As, Achim Heilig, C. Max Stevens, Charalampos Charalampidis, Robert S. Fausto, Elizabeth M. Morris, Ellen Mosley-Thompson, Lora Koenig, Lynn N. Montgomery, Clément Miège, Sebastian B. Simonsen, Thomas Ingeman-Nielsen, and Jason E. Box
The Cryosphere, 13, 845–859,Short summary
The perennial snow, or firn, on the Greenland ice sheet each summer stores part of the meltwater formed at the surface, buffering the ice sheet’s contribution to sea level. We gathered observations of firn air content, indicative of the space available in the firn to retain meltwater, and find that this air content remained stable in cold regions of the firn over the last 65 years but recently decreased significantly in western Greenland.
Marilena Oltmanns, Fiammetta Straneo, and Marco Tedesco
The Cryosphere, 13, 815–825,Short summary
By combining reanalysis, weather station and satellite data, we show that increases in surface melt over Greenland are initiated by large-scale precipitation events year-round. Estimates from a regional climate model suggest that the initiated melting more than doubled between 1988 and 2012, amounting to ~28 % of the overall melt and revealing that, despite the involved mass gain, precipitation events are contributing to the ice sheet's decline.
Emily A. Hill, G. Hilmar Gudmundsson, J. Rachel Carr, and Chris R. Stokes
The Cryosphere, 12, 3907–3921,Short summary
Floating ice tongues in Greenland buttress inland ice, and their removal could accelerate ice flow. Petermann Glacier recently lost large sections of its ice tongue, but there was little glacier acceleration. Here, we assess the impact of future calving events on ice speeds. We find that removing the lower portions of the ice tongue does not accelerate flow. However, future iceberg calving closer to the grounding line could accelerate ice flow and increase ice discharge and sea level rise.
Michalea D. King, Ian M. Howat, Seongsu Jeong, Myoung J. Noh, Bert Wouters, Brice Noël, and Michiel R. van den Broeke
The Cryosphere, 12, 3813–3825,Short summary
We derive the first continuous record of total ice discharged from all large Greenland outlet glaciers over the 2000–2016 period, resolving a distinct pattern of seasonal variability. We compare these results to glacier retreat and meltwater runoff and find that while runoff has a limited impact on ice discharge in summer, long-term changes in discharge are highly correlated to retreat. These results help to better understand Greenland outlet glacier sensitivity over a range of timescales.
Kang Yang, Laurence C. Smith, Leif Karlstrom, Matthew G. Cooper, Marco Tedesco, Dirk van As, Xiao Cheng, Zhuoqi Chen, and Manchun Li
The Cryosphere, 12, 3791–3811,Short summary
A high-resolution spatially lumped hydrologic surface routing model is proposed to simulate meltwater transport over bare ice surfaces. In an ice-covered catchment, meltwater is routed by slow interfluve flow (~10−3–10−4 m s−1) followed by fast open-channel flow (~10−1 m s−1). Seasonal evolution of supraglacial stream-river networks substantially alters the magnitude and timing of moulin discharge with implications for subglacial hydrology and ice dynamics.
Alison Delhasse, Xavier Fettweis, Christoph Kittel, Charles Amory, and Cécile Agosta
The Cryosphere, 12, 3409–3418,Short summary
Since the 2000s, an atmospheric circulation change (CC) gauged by a negative summer shift in the North Atlantic Oscillation has been observed, enhancing surface melt over the Greenland Ice Sheet (GrIS). Future GrIS surface mass balance (SMB) projections are based on global climate models that do not represent this CC. The model MAR has been used to show that previous estimates of these projections could have been significantly overestimated if this current circulation pattern persists.
Edward Hanna, Xavier Fettweis, and Richard J. Hall
The Cryosphere, 12, 3287–3292,Short summary
The latest/recent generations of global climate models do not simulate the recent (last 30 years) increase in atmospheric high pressure over Greenland in summer but rather projects decreasing pressure. This difference between climate models and observations raises serious questions about the ability of the models to accurately represent future changes in Greenland climate and ice-sheet mass balance. There are also likely effects on climate predictions downstream, e.g. over Europe.
Emily A. Hill, J. Rachel Carr, Chris R. Stokes, and G. Hilmar Gudmundsson
The Cryosphere, 12, 3243–3263,Short summary
The dynamic behaviour (i.e. acceleration and retreat) of outlet glaciers in northern Greenland remains understudied. Here, we provide a new long-term (68-year) record of terminus change. Overall, recent retreat rates (1995–2015) are higher than the last 47 years. Despite region-wide retreat, we found disparities in dynamic behaviour depending on terminus type; grounded glaciers accelerated and thinned following retreat, while glaciers with floating ice tongues were insensitive to recent retreat.
Benjamin H. Hills, Joel T. Harper, Toby W. Meierbachtol, Jesse V. Johnson, Neil F. Humphrey, and Patrick J. Wright
The Cryosphere, 12, 3215–3227,Short summary
At its surface, an ice sheet is closely connected to the climate. Assessing heat transfer between near-surface ice and the overlying atmosphere is important for understanding how the ice sheet is melting at the surface. We measured ice temperature within 20 m of the surface of the Greenland Ice Sheet. Resulting ice temperatures are warmer than the air, a peculiar result which implies the role of some nonconductive heat transfer processes such as latent heating by refreezing meltwater.
Reinhard Calov, Sebastian Beyer, Ralf Greve, Johanna Beckmann, Matteo Willeit, Thomas Kleiner, Martin Rückamp, Angelika Humbert, and Andrey Ganopolski
The Cryosphere, 12, 3097–3121,Short summary
We present RCP 4.5 and 8.5 projections for the Greenland glacial system with the new glacial system model IGLOO 1.0, which incorporates the ice sheet model SICOPOLIS 3.3, a model of basal hydrology and a parameterization of submarine melt of outlet glaciers. Surface temperature and mass balance anomalies from the MAR climate model serve as forcing delivering projections for the contribution of the Greenland ice sheet to sea level rise and submarine melt of Helheim and Store outlet glaciers.
Jiangjun Ran, Miren Vizcaino, Pavel Ditmar, Michiel R. van den Broeke, Twila Moon, Christian R. Steger, Ellyn M. Enderlin, Bert Wouters, Brice Noël, Catharina H. Reijmer, Roland Klees, Min Zhong, Lin Liu, and Xavier Fettweis
The Cryosphere, 12, 2981–2999,Short summary
To accurately predict future sea level rise, the mechanisms driving the observed mass loss must be better understood. Here, we combine data from the satellite gravimetry, surface mass balance, and ice discharge to analyze the mass budget of Greenland at various temporal scales. This study, for the first time, suggests the existence of a substantial meltwater storage during summer, with a peak value of 80–120 Gt in July. We highlight its importance for understanding ice sheet mass variability
Thomas M. Jordan, Christopher N. Williams, Dustin M. Schroeder, Yasmina M. Martos, Michael A. Cooper, Martin J. Siegert, John D. Paden, Philippe Huybrechts, and Jonathan L. Bamber
The Cryosphere, 12, 2831–2854,Short summary
Here, via analysis of radio-echo sounding data, we place a new observational constraint upon the basal water distribution beneath the Greenland Ice Sheet. In addition to the outlet glaciers, we demonstrate widespread water storage in the northern and eastern ice-sheet interior, a notable feature being a "corridor" of basal water extending from NorthGRIP to Petermann Glacier. The basal water distribution and its relationship with basal temperature provides a new constraint for numerical models.
Ian Joughin, Ben E. Smith, and Ian Howat
The Cryosphere, 12, 2211–2227,Short summary
We describe several new ice velocity maps produced using Landsat 8 and Copernicus Sentinel 1A/B data. We focus on several sites where we analyse these data in conjunction with earlier data from this project, which extend back to the year 2000. In particular, we find that Jakobshavn Isbræ began slowing substantially in 2017. The growing duration of these records will allow more robust analyses of the processes controlling fast flow and how they are affected by climate and other forcings.
Yukihiko Onuma, Nozomu Takeuchi, Sota Tanaka, Naoko Nagatsuka, Masashi Niwano, and Teruo Aoki
The Cryosphere, 12, 2147–2158,Short summary
Snow algal bloom can substantially increase melt rates of the snow due to the effect of albedo reduction on the snow surface. In this study, the temporal changes in algal abundance on the snowpacks of Greenland Glacier were studied in order to reproduce snow algal growth using a numerical model. Our study demonstrates that a simple numerical model could simulate the temporal variation in snow algal abundance on the glacier throughout the summer season.
Achim Heilig, Olaf Eisen, Michael MacFerrin, Marco Tedesco, and Xavier Fettweis
The Cryosphere, 12, 1851–1866,Short summary
This paper presents data on temporal changes in snow and firn, which were not available before. We present data on water infiltration in the percolation zone of the Greenland Ice Sheet that improve our understanding of liquid water retention in snow and firn and mass transfer. We compare those findings with model simulations. It appears that simulated accumulation in terms of SWE is fairly accurate, while modeling of the individual parameters density and liquid water content is incorrect.
Stefan R. M. Ligtenberg, Peter Kuipers Munneke, Brice P. Y. Noël, and Michiel R. van den Broeke
The Cryosphere, 12, 1643–1649,Short summary
Firn is the transitional product between fresh snow and glacier ice, and a 10-100 m thick layer covers the Greenland ice sheet. It has the capacity to store meltwater and thereby mitigate runoff to the ocean. Using a model and improved atmospheric forcing, we simulate firn density and temperature that agrees well with observations from firn cores. Especially in the regions with substantial melt, and therefore the most sensitive to a warming climate, the results improved significantly.
Konstanze Haubner, Jason E. Box, Nicole J. Schlegel, Eric Y. Larour, Mathieu Morlighem, Anne M. Solgaard, Kristian K. Kjeldsen, Signe H. Larsen, Eric Rignot, Todd K. Dupont, and Kurt H. Kjær
The Cryosphere, 12, 1511–1522,Short summary
We investigate the effect of neglecting calving on Upernavik Isstrøm, West Greenland, between 1849 and 2012. Our simulation is forced with observed terminus positions in discrete time steps and is responsive to the prescribed ice front changes. Simulated frontal retreat is needed to obtain a realistic ice surface elevation and velocity evolution of Upernavik. Using the prescribed terminus position change we gain insight to mass loss partitioning during different time periods.
Alley, R., Dupont, T., Parizek, B., and Anandakrishnan, S.: Access of surface meltwater to beds of sub-freezing glaciers: preliminary insights, Ann. Glaciol., 40, 8–14, 2005. a
Box, J. and Ski, K.: Remote sounding of Greenland supraglacial melt lakes: implications for subglacial hydraulics, J. Glaciol., 53, 257–265, 2007. a
Dieser, M., Broemsen, E., Cameron, K., King, G., Achberger, A., Choquette, K., Hagedorn, B., Sletten, R., Junge, K., and Christner, B.: Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet, ISME J., 8, 2305, https://doi.org/10.1038/ismej.2014.59, 2014. a
Dow, C., Kulessa, B., Rutt, I., Tsai, V., Pimentel, S., Doyle, S., Van As, D., Lindbäck, K., Pettersson, R., Jones, G., and Hubbard, A.: Modeling of subglacial hydrological development following rapid supraglacial lake drainage, J. Geophys. Res.-Earth, 120, 1127–1147, 2015. a
Doyle, S. H., Hubbard, A. L., Dow, C. F., Jones, G. A., Fitzpatrick, A., Gusmeroli, A., Kulessa, B., Lindback, K., Pettersson, R., and Box, J. E.: Ice tectonic deformation during the rapid in situ drainage of a supraglacial lake on the Greenland Ice Sheet, The Cryosphere, 7, 129–140, https://doi.org/10.5194/tc-7-129-2013, 2013. a, b
Dunmire, D., Lenaerts, J., Banwell, A., Wever, N., Shragge, J., Lhermitte, S., Drews, R., Pattyn, F., Hansen, J., Willis, I., Miller, J., and Keenan, E.: Observations of buried lake drainage on the Antarctic Ice Sheet, Geophys. Res. Lett., 47, e2020GL087970, https://doi.org/10.1029/2020GL087970, 2020. a
ESA: Sentinel-1, available at: https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/, last access: 23 March 2021. a
Hawkings, J., Wadham, J., Tranter, M., Telling, J., Bagshaw, E., Beaton, A., Simmons, S., Chandler, D., Tedstone, A., and Nienow, P.: The Greenland Ice Sheet as a hot spot of phosphorus weathering and export in the Arctic, Global Biogeochem. Cy., 30, 191–210, 2016. a
Hewitt, I.: Seasonal changes in ice sheet motion due to melt water lubrication, Earth Planet. Sci. Lett., 371, 16–25, 2013. a
Hoffman, M., Perego, M., Andrews, L., Price, S., Neumann, T., Johnson, J., Catania, G., and Lüthi, M.: Widespread moulin formation during supraglacial lake drainages in Greenland, Geophys. Res. Lett., 45, 778–788, 2018. a
Johansson, A. M. and Brown, I. A.: Observations of supra-glacial lakes in west Greenland using winter wide swath Synthetic Aperture Radar, Remote Sens. Lett., 3, 531–539, 2012. a
Koenig, L., Miège, C., Forster, R., and Brucker, L.: Initial in situ measurements of perennial meltwater storage in the Greenland firn aquifer, Geophys. Res. Lett., 41, 81–85, 2014. a
Koenig, L. S., Lampkin, D. J., Montgomery, L. N., Hamilton, S. L., Turrin, J. B., Joseph, C. A., Moutsafa, S. E., Panzer, B., Casey, K. A., Paden, J. D., Leuschen, C., and Gogineni, P.: Wintertime storage of water in buried supraglacial lakes across the Greenland Ice Sheet, The Cryosphere, 9, 1333–1342, https://doi.org/10.5194/tc-9-1333-2015, 2015. a
Koziol, C., Arnold, N., Pope, A., and Colgan, W.: Quantifying supraglacial meltwater pathways in the Paakitsoq region, West Greenland, J. Glaciol., 63, 464–476, 2017. a
Lamarche-Gagnon, G., Wadham, J., Lollar, B., Arndt, S., Fietzek, P., Beaton, A., Tedstone, A., Telling, J., Bagshaw, E., Hawkings, J., Kohler, T., Zarsky, J., Mowlem, M., Anesio, A., and Stibal, M.: Greenland melt drives continuous export of methane from the ice-sheet bed, Nature, 565, 73–77, 2019. a
Leeson, A., Shepherd, A., Sundal, A., Johansson, A., Selmes, N., Briggs, K., Hogg, A., and Fettweis, X.: A comparison of supraglacial lake observations derived from MODIS imagery at the western margin of the Greenland ice sheet, J. Glaciology, 59, 1179–1188, 2013. a
Liang, Y., Colgan, W., Lv, Q., Steffen, K., Abdalati, W., Stroeve, J., Gallaher, D., and Bayou, N.: A decadal investigation of supraglacial lakes in West Greenland using a fully automatic detection and tracking algorithm, Remote Sens. Environ., 123, 127–138, 2012. a
Lüthje, M., Pedersen, L., Reeh, N., and Greuell, W.: Modelling the evolution of supraglacial lakes on the West Greenland ice-sheet margin, J. Glaciol., 52, 608–618, 2006. a
Moussavi, M., Abdalati, W., Pope, A., Scambos, T., Tedesco, M., MacFerrin, M., and Grigsby, S.: Derivation and validation of supraglacial lake volumes on the Greenland Ice Sheet from high-resolution satellite imagery, Remote Sens. Environ., 183, 294–303, 2016. a
Noh, M. and Howat, I.: Automated stereo-photogrammetric DEM generation at high latitudes: Surface Extraction with TIN-based Search-space Minimization (SETSM) validation and demonstration over glaciated regions, GISci. Remote Sens., 52, 198–217, 2015. a
Pimentel, S. and Flowers, G.: A numerical study of hydrologically driven glacier dynamics and subglacial flooding, P. R. Soc. A, 467, 537–558, 2010. a
Pope, A., Scambos, T. A., Moussavi, M., Tedesco, M., Willis, M., Shean, D., and Grigsby, S.: Estimating supraglacial lake depth in West Greenland using Landsat 8 and comparison with other multispectral methods, The Cryosphere, 10, 15–27, https://doi.org/10.5194/tc-10-15-2016, 2016. a, b, c, d, e, f, g, h
Porter, C., Morin, P., Howat, I., Noh, M., Bates, B., Peterman, K., Keesey, S., Schlenk, M., Gardiner, J., Tomko, K., Willis, M., Kelleher, C., Cloutier, M., Husby, E., Foga, S., Nakamura, H., Platson, M., Wethington, M., Williamson, C., Bauer, G., Enos, J., Arnold, G., Kramer, W., Becker, P., Doshi, A., D’Souza, C., Cummens, P., Laurier, F., and Bojesen, M.: ArcticDEM, V1, https://doi.org/10.7910/DVN/OHHUKH, Harvard Dataverse, V1, 2018. a, b
Russell, A.: Supraglacial lake drainage near Sendre Strømjjord, Greenland, J. Glaciol., 39, 431–433, 1993. a
Shade, A., Peter, H., Allison, S., Baho, D., Berga, M., Bürgmann, H., Huber, D., Langenheder, S., Lennon, J., Martiny, J., Matulich, K., Schmidt, T., and Handelsman, J.: Fundamentals of microbial community resistance and resilience, Front. Microbiol., 3, 417, https://doi.org/10.3389/fmicb.2012.00417, 2012. a
U.S. Geological Survey: Landsat 8, available at: https://www.usgs.gov/core-science-systems/nli/landsat/landsat-8?qt-science_support_page_related_con=0#qt-science_support_page_related_con, last access: 23 March 2021. a
Wangchuk, S., Bolch, T., and Zawadzki, J.: Towards automated mapping and monitoring of potentially dangerous glacial lakes in Bhutan Himalaya using Sentinel-1 Synthetic Aperture Radar data, Int. J. Remote Sens., 40, 4642–4667, 2019. a
Werder, M., Hewitt, I., Schoof, C., and Flowers, G.: Modeling channelized and distributed subglacial drainage in two dimensions, J. Geophys. Res.-Earth, 118, 2140–2158, 2013. a
White, A., Mueller, D., and Copland, L.: Reconstructing hydrographic change in Petersen Bay, Ellesmere Island, Canada, inferred from SAR imagery, Remote Sens. Environ., 165, 1–13, 2015. a
The surface of the Greenland Ice Sheet contains thousands of surface lakes. These lakes can deliver water through cracks to the ice sheet base and influence the speed of ice flow. Here we look at instances of lakes draining in the middle of winter using the Sentinel-1 radar satellites. Winter-draining lakes can help us understand the mechanisms for lake drainages throughout the year and can point to winter movement of water that will impact our understanding of ice sheet hydrology.
The surface of the Greenland Ice Sheet contains thousands of surface lakes. These lakes can...