Articles | Volume 8, issue 2
https://doi.org/10.5194/tc-8-345-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/tc-8-345-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
03 Mar 2014
Research article |
| 03 Mar 2014
A range correction for ICESat and its potential impact on ice-sheet mass balance studies
A. A. Borsa
Scripps Institution of Oceanography, San Diego, California, USA
G. Moholdt
Scripps Institution of Oceanography, San Diego, California, USA
H. A. Fricker
Scripps Institution of Oceanography, San Diego, California, USA
K. M. Brunt
Morgan State University, Baltimore, Maryland, USA
GESTAR, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
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EGUsphere, https://doi.org/10.5194/egusphere-2024-1656, https://doi.org/10.5194/egusphere-2024-1656, 2024
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We measure shoreline change across a 7-km stretch of coastline on the Alaskan Beaufort Sea Coast between 2019–2022 using multispectral imagery from Planet and satellite altimetry from ICESat-2. We find that shoreline change rates are high and variable, and that different shoreline types show distinct patterns of change in shoreline position and topography. We discuss how the observed changes may be driven by both time-varying ocean and air conditions and spatial variations in morphology.
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The Cryosphere, 18, 5173–5206, https://doi.org/10.5194/tc-18-5173-2024, https://doi.org/10.5194/tc-18-5173-2024, 2024
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We develop a method for ice-sheet-scale retrieval of supraglacial meltwater depths using ICESat-2 photon data. We report results for two drainage basins in Greenland and Antarctica during two contrasting melt seasons, where our method reveals a total of 1249 lake segments up to 25 m deep. The large volume and wide variety of accurate depth data that our method provides enable the development of data-driven models of meltwater volumes in satellite imagery.
Marnie B. Bryant, Adrian A. Borsa, Claire C. Masteller, Roger J. Michaelides, Matthew R. Siegfried, Adam P. Young, and Eric J. Anderson
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We measure shoreline change across a 7-km stretch of coastline on the Alaskan Beaufort Sea Coast between 2019–2022 using multispectral imagery from Planet and satellite altimetry from ICESat-2. We find that shoreline change rates are high and variable, and that different shoreline types show distinct patterns of change in shoreline position and topography. We discuss how the observed changes may be driven by both time-varying ocean and air conditions and spatial variations in morphology.
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EGUsphere, https://doi.org/10.5194/egusphere-2024-1704, https://doi.org/10.5194/egusphere-2024-1704, 2024
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The Cryosphere, 17, 4079–4101, https://doi.org/10.5194/tc-17-4079-2023, https://doi.org/10.5194/tc-17-4079-2023, 2023
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We develop a method using ICESat-2 data to measure how Antarctic grounding lines (GLs) migrate across the tide cycle. At an ice plain on the Ronne Ice Shelf we observe 15 km of tidal GL migration, the largest reported distance in Antarctica, dominating any signal of long-term migration. We identify four distinct migration modes, which provide both observational support for models of tidal ice flexure and GL migration and insights into ice shelf–ocean–subglacial interactions in grounding zones.
Fernando S. Paolo, Alex S. Gardner, Chad A. Greene, Johan Nilsson, Michael P. Schodlok, Nicole-Jeanne Schlegel, and Helen A. Fricker
The Cryosphere, 17, 3409–3433, https://doi.org/10.5194/tc-17-3409-2023, https://doi.org/10.5194/tc-17-3409-2023, 2023
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The Cryosphere, 17, 2585–2606, https://doi.org/10.5194/tc-17-2585-2023, https://doi.org/10.5194/tc-17-2585-2023, 2023
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Antarctica's ice shelves (the floating extension of the ice sheet) help regulate ice flow. As ice shelves thin or lose contact with the bedrock, the upstream ice tends to accelerate, resulting in increased mass loss. Here, we use an ice sheet model to simulate the effect of seasonal sea surface height variations and see if we can reproduce observed seasonal variability of ice velocity on the ice shelf. When correctly parameterised, the model fits the observations well.
Anirudha Mahagaonkar, Geir Moholdt, and Thomas V. Schuler
The Cryosphere Discuss., https://doi.org/10.5194/tc-2023-4, https://doi.org/10.5194/tc-2023-4, 2023
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Surface meltwater lakes along the margins of the Antarctic Ice Sheet can be important for ice shelf dynamics and stability. We used optical satellite imagery to study seasonal evolution of meltwater lakes in Dronning Maud Land. We found large interannual variability in lake extents, but with consistent seasonal patterns. Although correlation with summer air temperature was strong locally, other climatic and environmental factors need to be considered to explain the large regional variability.
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The Cryosphere, 14, 4253–4263, https://doi.org/10.5194/tc-14-4253-2020, https://doi.org/10.5194/tc-14-4253-2020, 2020
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Ice on glaciers and ice sheets may melt and pond on ice surfaces in summer months. Detection and observation of these meltwater ponds is important for understanding glaciers and ice sheets, and satellite imagery has been used in previous work. However, image-based methods struggle with deep water, so we used data from the Ice, Clouds, and land Elevation Satellite-2 (ICESat-2) and the Airborne Topographic Mapper (ATM) to demonstrate the potential for lidar depth monitoring.
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The Cryosphere, 14, 3287–3308, https://doi.org/10.5194/tc-14-3287-2020, https://doi.org/10.5194/tc-14-3287-2020, 2020
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The Cryosphere, 13, 2579–2595, https://doi.org/10.5194/tc-13-2579-2019, https://doi.org/10.5194/tc-13-2579-2019, 2019
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In this study, we used a ground-penetrating radar technique to measure melting at high precision under Nivlisen, an ice shelf in central Dronning Maud Land, East Antarctica. We found that summer-warmed ocean surface waters can increase melting close to the ice shelf front. Our study shows the use of and need for measurements in the field to monitor Antarctica's coastal margins; these detailed variations in basal melting are not captured in satellite data but are vital to predict future changes.
Christopher J. Crawford, Jeannette van den Bosch, Kelly M. Brunt, Milton G. Hom, John W. Cooper, David J. Harding, James J. Butler, Philip W. Dabney, Thomas A. Neumann, Craig S. Cleckner, and Thorsten Markus
Atmos. Meas. Tech., 12, 1913–1933, https://doi.org/10.5194/amt-12-1913-2019, https://doi.org/10.5194/amt-12-1913-2019, 2019
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Kelly M. Brunt, Thomas A. Neumann, and Christopher F. Larsen
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This paper provides an assessment of new GPS elevation data collected near the South Pole, Antarctica, that will ultimately be used for ICESat-2 satellite elevation data validation. Further, using the new ground-based GPS data, this paper provides an assessment of airborne lidar elevation data collected between 2014 and 2017, which will also be used for ICESat-2 data validation.
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For the large majority of glaciers and ice caps, there is no information on the thickness of the ice cover. Any attempt to predict glacier demise under climatic warming and to estimate the future contribution to sea-level rise is limited as long as the glacier thickness is not well constrained. Here, we present a two-step mass-conservation approach for mapping ice thickness. Measurements are naturally reproduced. The reliability is readily assessible from a complementary map of error estimates.
Laurence Gray, David Burgess, Luke Copland, Thorben Dunse, Kirsty Langley, and Geir Moholdt
The Cryosphere, 11, 1041–1058, https://doi.org/10.5194/tc-11-1041-2017, https://doi.org/10.5194/tc-11-1041-2017, 2017
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We use surface height data from west Greenland and Devon Ice Cap to check the performance of the new interferometric mode of the ESA CryoSat radar altimeter. The detailed height comparison allows an improved system calibration and processing methodology and measurement of the height of supraglacial lakes which form each summer around the periphery of the Greenland Ice Cap. The advantages of the SARIn mode suggest that future satellite radar altimeters for glacial ice should use this technology.
Kelly M. Brunt, Robert L. Hawley, Eric R. Lutz, Michael Studinger, John G. Sonntag, Michelle A. Hofton, Lauren C. Andrews, and Thomas A. Neumann
The Cryosphere, 11, 681–692, https://doi.org/10.5194/tc-11-681-2017, https://doi.org/10.5194/tc-11-681-2017, 2017
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This manuscript presents an analysis of NASA airborne lidar data based on in situ GPS measurements from the interior of the Greenland Ice Sheet. Results show that for two airborne altimeters, surface elevation biases are less than 0.12 m and measurement precisions are 0.09 m or better. The study concludes that two NASA airborne lidars are sufficiently characterized to form part of a satellite data validation strategy, specifically for ICESat-2, scheduled to launch in 2018.
Kelly M. Brunt, Thomas A. Neumann, Jason M. Amundson, Jeffrey L. Kavanaugh, Mahsa S. Moussavi, Kaitlin M. Walsh, William B. Cook, and Thorsten Markus
The Cryosphere, 10, 1707–1719, https://doi.org/10.5194/tc-10-1707-2016, https://doi.org/10.5194/tc-10-1707-2016, 2016
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This paper highlights results from a 2014 airborne laser altimetry campaign over Alaskan glaciers. The study was conducted in support of a NASA satellite mission (ICESat-2, scheduled to launch in 2017). The study indicates that the planned beam configuration for ICESat-2 is ideal for determining local slope, which is critical for the determination of ice-sheet elevation change. Results also suggest that ICESat-2 will contribute significantly to glacier studies in the mid-latitudes.
P. R. Holland, A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming
The Cryosphere, 9, 1005–1024, https://doi.org/10.5194/tc-9-1005-2015, https://doi.org/10.5194/tc-9-1005-2015, 2015
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Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf's snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a 'compressive arch' in strain rates.
S. P. Carter, H. A. Fricker, and M. R. Siegfried
The Cryosphere Discuss., https://doi.org/10.5194/tcd-9-2053-2015, https://doi.org/10.5194/tcd-9-2053-2015, 2015
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We develop a model that simulated the observed filling and draining of active subglacial lakes in Antarctica that suggests the may occurs by the erosion of channels into deformable subglacial sediments, that then deform shut as lake level declines. This contrasts with ice dammed alpine lakes which drain by channels incised into ice. If active subglacial lakes require deformable sediments to fill and drain as observed, then classic radar-based methods of lake detection may fail to find them.
W. Colgan, W. Abdalati, M. Citterio, B. Csatho, X. Fettweis, S. Luthcke, G. Moholdt, and M. Stober
The Cryosphere Discuss., https://doi.org/10.5194/tcd-8-537-2014, https://doi.org/10.5194/tcd-8-537-2014, 2014
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The Cryosphere Discuss., https://doi.org/10.5194/tcd-7-5433-2013, https://doi.org/10.5194/tcd-7-5433-2013, 2013
Revised manuscript not accepted
C. Nuth, J. Kohler, M. König, A. von Deschwanden, J. O. Hagen, A. Kääb, G. Moholdt, and R. Pettersson
The Cryosphere, 7, 1603–1621, https://doi.org/10.5194/tc-7-1603-2013, https://doi.org/10.5194/tc-7-1603-2013, 2013
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The Cryosphere, 7, 1227–1245, https://doi.org/10.5194/tc-7-1227-2013, https://doi.org/10.5194/tc-7-1227-2013, 2013
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Assessing the potential for ice flow piracy between the Totten and Vanderford glaciers, East Antarctica
Stagnant ice and age modelling in the Dome C region, Antarctica
Polar firn properties in Greenland and Antarctica and related effects on microwave brightness temperatures
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The Cryosphere, 18, 5207–5238, https://doi.org/10.5194/tc-18-5207-2024, https://doi.org/10.5194/tc-18-5207-2024, 2024
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We combined a numerical model with radar measurements in order to determine the age of ice in the Dome C region of Antarctica. Our results show that at the current ice core drilling sites on Little Dome C, the maximum age of the ice is almost 1.5 Ma. We also highlight a new potential drill site called North Patch with ice up to 2 Ma. Finally, we explore the nature of a stagnant ice layer at the base of the ice sheet which has been independently observed and modelled but is not well understood.
Haokui Xu, Brooke Medley, Leung Tsang, Joel T. Johnson, Kenneth C. Jezek, Macro Brogioni, and Lars Kaleschke
The Cryosphere, 17, 2793–2809, https://doi.org/10.5194/tc-17-2793-2023, https://doi.org/10.5194/tc-17-2793-2023, 2023
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Tilly Woods and Ian J. Hewitt
The Cryosphere, 17, 1967–1987, https://doi.org/10.5194/tc-17-1967-2023, https://doi.org/10.5194/tc-17-1967-2023, 2023
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Solar radiation causes melting at and just below the surface of the Greenland ice sheet, forming a porous surface layer known as the weathering crust. The weathering crust is home to many microbes, and the growth of these microbes is linked to the melting of the weathering crust and vice versa. We use a mathematical model to investigate what controls the size and structure of the weathering crust, the number of microbes within it, and its sensitivity to climate change.
Sebastian Hinck, Evan J. Gowan, Xu Zhang, and Gerrit Lohmann
The Cryosphere, 16, 941–965, https://doi.org/10.5194/tc-16-941-2022, https://doi.org/10.5194/tc-16-941-2022, 2022
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Proglacial lakes were pervasive along the retreating continental ice margins after the Last Glacial Maximum. Similarly to the marine ice boundary, interactions at the ice-lake interface impact ice sheet dynamics and mass balance. Previous numerical ice sheet modeling studies did not include a dynamical lake boundary. We describe the implementation of an adaptive lake boundary condition in PISM and apply the model to the glacial retreat of the Laurentide Ice Sheet.
Heiko Goelzer, Brice P. Y. Noël, Tamsin L. Edwards, Xavier Fettweis, Jonathan M. Gregory, William H. Lipscomb, Roderik S. W. van de Wal, and Michiel R. van den Broeke
The Cryosphere, 14, 1747–1762, https://doi.org/10.5194/tc-14-1747-2020, https://doi.org/10.5194/tc-14-1747-2020, 2020
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Future sea-level change projections with process-based ice sheet models are typically driven with surface mass balance forcing derived from climate models. In this work we address the problems arising from a mismatch of the modelled ice sheet geometry with the one used by the climate model. The proposed remapping method reproduces the original forcing data closely when applied to the original geometry and produces a physically meaningful forcing when applied to different modelled geometries.
Heiko Goelzer, Violaine Coulon, Frank Pattyn, Bas de Boer, and Roderik van de Wal
The Cryosphere, 14, 833–840, https://doi.org/10.5194/tc-14-833-2020, https://doi.org/10.5194/tc-14-833-2020, 2020
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In our ice-sheet modelling experience and from exchange with colleagues in different groups, we found that it is not always clear how to calculate the sea-level contribution from a marine ice-sheet model. This goes hand in hand with a lack of documentation and transparency in the published literature on how the sea-level contribution is estimated in different models. With this brief communication, we hope to stimulate awareness and discussion in the community to improve on this situation.
Tanja Schlemm and Anders Levermann
The Cryosphere, 13, 2475–2488, https://doi.org/10.5194/tc-13-2475-2019, https://doi.org/10.5194/tc-13-2475-2019, 2019
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We provide a simple stress-based parameterization for cliff calving of ice sheets. According to the resulting increasing dependence of the calving rate on ice thickness, the parameterization might lead to a runaway ice loss in large parts of Greenland and Antarctica.
Anders Levermann and Johannes Feldmann
The Cryosphere, 13, 1621–1633, https://doi.org/10.5194/tc-13-1621-2019, https://doi.org/10.5194/tc-13-1621-2019, 2019
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Using scaling analysis we propose that the currently observed marine ice-sheet instability in the Amundsen Sea sector might be faster than all other potential instabilities in Antarctica.
Veronika Emetc, Paul Tregoning, Mathieu Morlighem, Chris Borstad, and Malcolm Sambridge
The Cryosphere, 12, 3187–3213, https://doi.org/10.5194/tc-12-3187-2018, https://doi.org/10.5194/tc-12-3187-2018, 2018
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The paper includes a model that can be used to predict zones of fracture formation in both floating and grounded ice in Antarctica. We used observations and a statistics-based model to predict fractures in most ice shelves in Antarctica as an alternative to the damage-based approach. We can predict the location of observed fractures with an average success rate of 84% for grounded ice and 61% for floating ice and mean overestimation error of 26% and 20%, respectively.
Sue Cook, Jan Åström, Thomas Zwinger, Benjamin Keith Galton-Fenzi, Jamin Stevens Greenbaum, and Richard Coleman
The Cryosphere, 12, 2401–2411, https://doi.org/10.5194/tc-12-2401-2018, https://doi.org/10.5194/tc-12-2401-2018, 2018
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The growth of fractures on Antarctic ice shelves is important because it controls the amount of ice lost as icebergs. We use a model constructed of multiple interconnected blocks to predict the locations where fractures will form on the Totten Ice Shelf in East Antarctica. The results show that iceberg calving is controlled not only by fractures forming near the front of the ice shelf but also by fractures which formed many kilometres upstream.
Heiko Goelzer, Sophie Nowicki, Tamsin Edwards, Matthew Beckley, Ayako Abe-Ouchi, Andy Aschwanden, Reinhard Calov, Olivier Gagliardini, Fabien Gillet-Chaulet, Nicholas R. Golledge, Jonathan Gregory, Ralf Greve, Angelika Humbert, Philippe Huybrechts, Joseph H. Kennedy, Eric Larour, William H. Lipscomb, Sébastien Le clec'h, Victoria Lee, Mathieu Morlighem, Frank Pattyn, Antony J. Payne, Christian Rodehacke, Martin Rückamp, Fuyuki Saito, Nicole Schlegel, Helene Seroussi, Andrew Shepherd, Sainan Sun, Roderik van de Wal, and Florian A. Ziemen
The Cryosphere, 12, 1433–1460, https://doi.org/10.5194/tc-12-1433-2018, https://doi.org/10.5194/tc-12-1433-2018, 2018
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We have compared a wide spectrum of different initialisation techniques used in the ice sheet modelling community to define the modelled present-day Greenland ice sheet state as a starting point for physically based future-sea-level-change projections. Compared to earlier community-wide comparisons, we find better agreement across different models, which implies overall improvement of our understanding of what is needed to produce such initial states.
Alex S. Gardner, Geir Moholdt, Ted Scambos, Mark Fahnstock, Stefan Ligtenberg, Michiel van den Broeke, and Johan Nilsson
The Cryosphere, 12, 521–547, https://doi.org/10.5194/tc-12-521-2018, https://doi.org/10.5194/tc-12-521-2018, 2018
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We map present-day Antarctic surface velocities from Landsat imagery and compare to earlier estimates from radar. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and the western Antarctic Peninsula, account for 89 % of the observed increase in ice discharge. In contrast, glaciers draining the East Antarctic have been remarkably stable. Our work suggests that patterns of mass loss are part of a longer-term phase of enhanced flow.
ice sheet volume
Troels Bøgeholm Mikkelsen, Aslak Grinsted, and Peter Ditlevsen
The Cryosphere, 12, 39–47, https://doi.org/10.5194/tc-12-39-2018, https://doi.org/10.5194/tc-12-39-2018, 2018
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The atmospheric temperature increase poses a real risk of ice sheets collapsing. We show that this risk might have been underestimated since variations in temperature will move the ice sheets to the tipping point of destabilization.
We show this by using a simple computer model of a large ice sheet and investigate what happens if the temperature varies from year to year. The total volume of the ice sheet decreases because a cold year followed by an equally warm year do not cancel out.
David E. Shean, Knut Christianson, Kristine M. Larson, Stefan R. M. Ligtenberg, Ian R. Joughin, Ben E. Smith, C. Max Stevens, Mitchell Bushuk, and David M. Holland
The Cryosphere, 11, 2655–2674, https://doi.org/10.5194/tc-11-2655-2017, https://doi.org/10.5194/tc-11-2655-2017, 2017
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We used long-term GPS data and interferometric reflectometry (GPS-IR) to measure velocity, strain rate and surface elevation for the PIG ice shelf – a site of significant mass loss in recent decades. We combined these observations with high-res DEMs and firn model output to constrain surface mass balance and basal melt rates. We document notable spatial variability in basal melt rates but limited temporal variability from 2012 to 2014 despite significant changes in sub-shelf ocean heat content.
Wolfgang Rack, Matt A. King, Oliver J. Marsh, Christian T. Wild, and Dana Floricioiu
The Cryosphere, 11, 2481–2490, https://doi.org/10.5194/tc-11-2481-2017, https://doi.org/10.5194/tc-11-2481-2017, 2017
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Predicting changes of the Antarctic Ice Sheet involves fully understanding ice dynamics at the transition between grounded and floating ice. We map tidal bending of ice by satellite using InSAR, and we use precise GPS measurements with assumptions of tidal elastic bending to better interpret the satellite signal. It allows us to better define the grounding-line position and to refine the shape of tidal flexure profiles.
Christian Schoof, Andrew D. Davis, and Tiberiu V. Popa
The Cryosphere, 11, 2283–2303, https://doi.org/10.5194/tc-11-2283-2017, https://doi.org/10.5194/tc-11-2283-2017, 2017
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We show mathematically and computationally how discharge of ice from ocean-terminating glaciers is controlled by a combination of different forces acting on ice near the grounding line of a glacier and how that combination of forces is affected by the process of iceberg formation, which limits the length of floating ice tongues extending in front of the glacier. We show that a deeper fjord may lead to a longer ice tongue providing greater drag on the glacier, slowing the rate of ice discharge.
Joel Brown, Joel Harper, and Neil Humphrey
The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, https://doi.org/10.5194/tc-11-669-2017, 2017
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We use ground-penetrating radar surveys in conjunction with borehole depth and temperature data to estimate the liquid water content (wetness) of glacial ice in the ablation zone of an outlet glacier on the western side of the Greenland Ice Sheet. Our results show that the wetness of a warm basal ice layer is approximately 2.9 % to 4.6 % in our study region. This high level of wetness requires special attention when modelling ice dynamics or estimating ice thickness in the region.
Lionel Favier, Frank Pattyn, Sophie Berger, and Reinhard Drews
The Cryosphere, 10, 2623–2635, https://doi.org/10.5194/tc-10-2623-2016, https://doi.org/10.5194/tc-10-2623-2016, 2016
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We demonstrate the short-term unstable retreat of an East Antarctic outlet glacier triggered by imposed sub-ice-shelf melt, compliant with current values, using a state-of-the-art ice-sheet model. We show that pinning points – topographic highs in contact with the ice-shelf base – have a major impact on ice-sheet stability and timing of grounding-line retreat. The study therefore calls for improving our knowledge of sub-ice-shelf bathymetry in order to reduce uncertainties in future ice loss.
Alexander A. Robel, Christian Schoof, and Eli Tziperman
The Cryosphere, 10, 1883–1896, https://doi.org/10.5194/tc-10-1883-2016, https://doi.org/10.5194/tc-10-1883-2016, 2016
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Portions of the Antarctic Ice Sheet edge that rest on upward-sloping beds have the potential to collapse irreversibly and raise global sea level. Using a numerical model, we show that changes in the slipperiness of sediments beneath fast-flowing ice streams can cause them to persist on upward-sloping beds for hundreds to thousands of years before reversing direction. This type of behavior is important to consider as a possibility when interpreting observations of ongoing ice sheet change.
Johannes Feldmann and Anders Levermann
The Cryosphere, 10, 1753–1769, https://doi.org/10.5194/tc-10-1753-2016, https://doi.org/10.5194/tc-10-1753-2016, 2016
T. M. Jordan, J. L. Bamber, C. N. Williams, J. D. Paden, M. J. Siegert, P. Huybrechts, O. Gagliardini, and F. Gillet-Chaulet
The Cryosphere, 10, 1547–1570, https://doi.org/10.5194/tc-10-1547-2016, https://doi.org/10.5194/tc-10-1547-2016, 2016
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Ice penetrating radar enables determination of the basal properties of ice sheets. Existing algorithms assume stationarity in the attenuation rate, which is not justifiable at an ice sheet scale. We introduce the first ice-sheet-wide algorithm for radar attenuation that incorporates spatial variability, using the temperature field from a numerical model as an initial guess. The study is a step toward ice-sheet-wide data products for basal properties and evaluation of model temperature fields.
Hongyu Zhu, Noemi Petra, Georg Stadler, Tobin Isaac, Thomas J. R. Hughes, and Omar Ghattas
The Cryosphere, 10, 1477–1494, https://doi.org/10.5194/tc-10-1477-2016, https://doi.org/10.5194/tc-10-1477-2016, 2016
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We study how well the basal geothermal heat flux can be inferred from surface velocity observations using a thermomechanically coupled nonlinear Stokes ice sheet model. The prospects and limitations of this inversion is studied in two and three dimensional model problems. We also argue that a one-way coupled approach for the adjoint equations motivated by staggered solvers for forward multiphysics problems can lead to an incorrect gradient and premature termination of the optimization iteration.
Eythor Gudlaugsson, Angelika Humbert, Thomas Kleiner, Jack Kohler, and Karin Andreassen
The Cryosphere, 10, 751–760, https://doi.org/10.5194/tc-10-751-2016, https://doi.org/10.5194/tc-10-751-2016, 2016
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This paper explores the influence of a subglacial lake on ice dynamics and internal layers by means of numerical modelling as well as simulating the effect of a subglacial drainage event on isochrones. We provide an explanation for characteristic dip and ridge features found at the edges of many subglacial lakes and conclude that draining lakes can result in travelling waves at depth within isochrones, thus indicating the possibility of detecting past drainage events with ice penetrating radar.
T. Hughes, A. Sargent, J. Fastook, K. Purdon, J. Li, J.-B. Yan, and S. Gogineni
The Cryosphere, 10, 193–225, https://doi.org/10.5194/tc-10-193-2016, https://doi.org/10.5194/tc-10-193-2016, 2016
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The Antarctic and Greenland ice sheets are drained primarily by fast ice streams that end as ice shelves if they become afloat. Smooth transitions from slow sheet flow to fast stream flow to confined shelf flow are obtained and applied to Byrd Glacier in Antarctica after two upstream subglacial lakes suddenly drained in 2006, and to Jakobshavn Isbrae in Greenland after a confined ice shelf suddenly disintegrated in 2002. Byrd Glacier quickly stabilized, but Jakobshavn Isbrae remains unstable.
F. Saito, A. Abe-Ouchi, K. Takahashi, and H. Blatter
The Cryosphere, 10, 43–63, https://doi.org/10.5194/tc-10-43-2016, https://doi.org/10.5194/tc-10-43-2016, 2016
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This article, as the title denotes, is a follow-up study of an ice-sheet intercomparison project SeaRISE, which focuses on the response of the Greenland ice sheet to future global warming. The projections of the different SeaRISE prticipants show diversion, which has not been examined in detail to date. This study detects the main sources of the diversion by a number of sensitivity experiments and shows the importance of initialization methods as well as climate forcing methods.
P. Kuipers Munneke, S. R. M. Ligtenberg, B. P. Y. Noël, I. M. Howat, J. E. Box, E. Mosley-Thompson, J. R. McConnell, K. Steffen, J. T. Harper, S. B. Das, and M. R. van den Broeke
The Cryosphere, 9, 2009–2025, https://doi.org/10.5194/tc-9-2009-2015, https://doi.org/10.5194/tc-9-2009-2015, 2015
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The snow layer on top of the Greenland Ice Sheet is changing: it is thickening in the high and cold interior due to increased snowfall, while it is thinning around the margins. The marginal thinning is caused by compaction, and by more melt.
This knowledge is important: there are satellites that measure volume change of the ice sheet. It can be caused by increased ice discharge, or by compaction of the snow layer. Here, we quantify the latter, so that we can translate volume to mass change.
T. Goelles, C. E. Bøggild, and R. Greve
The Cryosphere, 9, 1845–1856, https://doi.org/10.5194/tc-9-1845-2015, https://doi.org/10.5194/tc-9-1845-2015, 2015
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Soot (black carbon) and dust particles darken the surface of ice sheets and glaciers as they accumulate. This causes more ice to melt, which releases more particles from within the ice. This positive feedback mechanism is studied with a new two-dimensional model, mimicking the conditions of Greenland, under different climate warming scenarios. In the warmest scenario, the additional ice sheet mass loss until the year 3000 is up to 7%.
S. H. R. Rosier, G. H. Gudmundsson, and J. A. M. Green
The Cryosphere, 9, 1649–1661, https://doi.org/10.5194/tc-9-1649-2015, https://doi.org/10.5194/tc-9-1649-2015, 2015
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We use a full-Stokes model to investigate the long period modulation of Rutford Ice Stream flow by the ocean tide. We find that using a nonlinear sliding law cannot fully explain the measurements and an additional mechanism, whereby tidally induced subglacial pressure variations are transmitted upstream from the grounding line, is also required to match the large amplitude and decay length scale of the observations.
R. Drews
The Cryosphere, 9, 1169–1181, https://doi.org/10.5194/tc-9-1169-2015, https://doi.org/10.5194/tc-9-1169-2015, 2015
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Floating ice shelves extend the continental ice of Antarctica seawards and mediate ice-ocean interactions. Many ice shelves are incised with channels where basal melting is enhanced. With data and modeling it is shown how the channel geometry depends on basal melting and along-flow advection (also for channels which are not freely floating), and how channel formation imprints the general flow pattern. This opens up the opportunity to map the channel formation from surface velocities only.
P. R. Holland, A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming
The Cryosphere, 9, 1005–1024, https://doi.org/10.5194/tc-9-1005-2015, https://doi.org/10.5194/tc-9-1005-2015, 2015
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Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf's snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a 'compressive arch' in strain rates.
M. Bügelmayer, D. M. Roche, and H. Renssen
The Cryosphere, 9, 821–835, https://doi.org/10.5194/tc-9-821-2015, https://doi.org/10.5194/tc-9-821-2015, 2015
A. Diez and O. Eisen
The Cryosphere, 9, 367–384, https://doi.org/10.5194/tc-9-367-2015, https://doi.org/10.5194/tc-9-367-2015, 2015
A. Diez, O. Eisen, C. Hofstede, A. Lambrecht, C. Mayer, H. Miller, D. Steinhage, T. Binder, and I. Weikusat
The Cryosphere, 9, 385–398, https://doi.org/10.5194/tc-9-385-2015, https://doi.org/10.5194/tc-9-385-2015, 2015
R. Calov, A. Robinson, M. Perrette, and A. Ganopolski
The Cryosphere, 9, 179–196, https://doi.org/10.5194/tc-9-179-2015, https://doi.org/10.5194/tc-9-179-2015, 2015
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Ice discharge into the ocean from outlet glaciers is an important
component of mass loss of the Greenland ice sheet. Here, we present a
simple parameterization of ice discharge for coarse resolution ice
sheet models, suitable for large ensembles or long-term palaeo
simulations. This parameterization reproduces in a good approximation
the present-day ice discharge compared with estimates, and the
simulation of the present-day ice sheet elevation is considerably
improved.
V. Helm, A. Humbert, and H. Miller
The Cryosphere, 8, 1539–1559, https://doi.org/10.5194/tc-8-1539-2014, https://doi.org/10.5194/tc-8-1539-2014, 2014
A. Robinson and H. Goelzer
The Cryosphere, 8, 1419–1428, https://doi.org/10.5194/tc-8-1419-2014, https://doi.org/10.5194/tc-8-1419-2014, 2014
G. R. Leguy, X. S. Asay-Davis, and W. H. Lipscomb
The Cryosphere, 8, 1239–1259, https://doi.org/10.5194/tc-8-1239-2014, https://doi.org/10.5194/tc-8-1239-2014, 2014
I. Joughin, B. E. Smith, D. E. Shean, and D. Floricioiu
The Cryosphere, 8, 209–214, https://doi.org/10.5194/tc-8-209-2014, https://doi.org/10.5194/tc-8-209-2014, 2014
C. P. Borstad, E. Rignot, J. Mouginot, and M. P. Schodlok
The Cryosphere, 7, 1931–1947, https://doi.org/10.5194/tc-7-1931-2013, https://doi.org/10.5194/tc-7-1931-2013, 2013
V. R. Barletta, L. S. Sørensen, and R. Forsberg
The Cryosphere, 7, 1411–1432, https://doi.org/10.5194/tc-7-1411-2013, https://doi.org/10.5194/tc-7-1411-2013, 2013
I. Joughin, S. B. Das, G. E. Flowers, M. D. Behn, R. B. Alley, M. A. King, B. E. Smith, J. L. Bamber, M. R. van den Broeke, and J. H. van Angelen
The Cryosphere, 7, 1185–1192, https://doi.org/10.5194/tc-7-1185-2013, https://doi.org/10.5194/tc-7-1185-2013, 2013
A. Aschwanden, G. Aðalgeirsdóttir, and C. Khroulev
The Cryosphere, 7, 1083–1093, https://doi.org/10.5194/tc-7-1083-2013, https://doi.org/10.5194/tc-7-1083-2013, 2013
J. De Rydt, G. H. Gudmundsson, H. F. J. Corr, and P. Christoffersen
The Cryosphere, 7, 407–417, https://doi.org/10.5194/tc-7-407-2013, https://doi.org/10.5194/tc-7-407-2013, 2013
W. Leng, L. Ju, M. Gunzburger, and S. Price
The Cryosphere, 7, 19–29, https://doi.org/10.5194/tc-7-19-2013, https://doi.org/10.5194/tc-7-19-2013, 2013
F. Gillet-Chaulet, O. Gagliardini, H. Seddik, M. Nodet, G. Durand, C. Ritz, T. Zwinger, R. Greve, and D. G. Vaughan
The Cryosphere, 6, 1561–1576, https://doi.org/10.5194/tc-6-1561-2012, https://doi.org/10.5194/tc-6-1561-2012, 2012
S. Fujita, P. Holmlund, K. Matsuoka, H. Enomoto, K. Fukui, F. Nakazawa, S. Sugiyama, and S. Surdyk
The Cryosphere, 6, 1203–1219, https://doi.org/10.5194/tc-6-1203-2012, https://doi.org/10.5194/tc-6-1203-2012, 2012
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