Articles | Volume 15, issue 8
https://doi.org/10.5194/tc-15-3655-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-15-3655-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 Aug 2021
Research article |
| 06 Aug 2021
| 06 Aug 2021
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model
Tamara Annina Gerber
CORRESPONDING AUTHOR
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Christine Schøtt Hvidberg
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Sune Olander Rasmussen
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Steven Franke
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Giulia Sinnl
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Aslak Grinsted
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Daniela Jansen
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Dorthe Dahl-Jensen
Section for the Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Centre for Earth Observation Science, University of Manitoba, Winnipeg, Canada
Related authors
Tamara Annina Gerber, David A. Lilien, Niels F. Nymand, Daniel Steinhage, Olaf Eisen, and Dorthe Dahl-Jensen
The Cryosphere, 19, 1955–1971, https://doi.org/10.5194/tc-19-1955-2025, https://doi.org/10.5194/tc-19-1955-2025, 2025
Short summary
Short summary
This study examines how anisotropic scattering and birefringence affect radar signals in ice sheets. Using data from northeast Greenland, we show that anisotropic scattering – driven by subtle ice crystal orientation changes – dominates the azimuthal power response. We find a strong link between scattering strength, orientation, and stratigraphy. This suggests anisotropic scattering can reveal crystal fabric orientation and differentiate ice units from distinct climatic periods.
Ole Zeising, Tamara Annina Gerber, Olaf Eisen, M. Reza Ershadi, Nicolas Stoll, Ilka Weikusat, and Angelika Humbert
The Cryosphere, 17, 1097–1105, https://doi.org/10.5194/tc-17-1097-2023, https://doi.org/10.5194/tc-17-1097-2023, 2023
Short summary
Short summary
The flow of glaciers and ice streams is influenced by crystal fabric orientation. Besides sparse ice cores, these can be investigated by radar measurements. Here, we present an improved method which allows us to infer the horizontal fabric asymmetry using polarimetric phase-sensitive radar data. A validation of the method on a deep ice core from the Greenland Ice Sheet shows an excellent agreement, which is a large improvement over previously used methods.
Steven Franke, Daniela Jansen, Tobias Binder, John D. Paden, Nils Dörr, Tamara A. Gerber, Heinrich Miller, Dorthe Dahl-Jensen, Veit Helm, Daniel Steinhage, Ilka Weikusat, Frank Wilhelms, and Olaf Eisen
Earth Syst. Sci. Data, 14, 763–779, https://doi.org/10.5194/essd-14-763-2022, https://doi.org/10.5194/essd-14-763-2022, 2022
Short summary
Short summary
The Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland. In order to better understand the past and future dynamics of the NEGIS, we present a high-resolution airborne radar data set (EGRIP-NOR-2018) for the onset region of the NEGIS. The survey area is centered at the location of the drill site of the East Greenland Ice-Core Project (EastGRIP), and radar profiles cover both shear margins and are aligned parallel to several flow lines.
Josephine Yolanda Lindsey-Clark, Aslak Grinsted, Baptiste Vandecrux, and Christine Schøtt Hvidberg
EGUsphere, https://doi.org/10.5194/egusphere-2025-2516, https://doi.org/10.5194/egusphere-2025-2516, 2025
This preprint is open for discussion and under review for The Cryosphere (TC).
Short summary
Short summary
We present a new method to improve estimates of snowfall across Greenland, a crucial factor in predicting sea-level rise. Current climate models often misrepresent snowfall patterns, resulting in significant long-term errors. By using two million observations, our method corrects model errors and produces more accurate snowfall maps. The improved maps can help to reduce uncertainty in sea-level rise projections and enhance understanding of Greenland’s proximity to critical melting thresholds.
Steven Franke, Mara Neudert, Veit Helm, Arttu Jutila, Océane Hames, Niklas Neckel, Stefanie Arndt, and Christian Haas
EGUsphere, https://doi.org/10.5194/egusphere-2025-2657, https://doi.org/10.5194/egusphere-2025-2657, 2025
This preprint is open for discussion and under review for The Cryosphere (TC).
Short summary
Short summary
Our research explored how icebergs affect the distribution of snow and flooding on Antarctic coastal sea ice. Using aircraft-based radar and laser scanning, we found that icebergs create thick snow drifts on their wind-facing sides and leave snow-free zones in their lee. The weight of these snow drifts often causes the ice below to flood, forming slush. These patterns, driven by wind and iceberg placement, are crucial for understanding sea ice changes and improving climate models.
Tamara Annina Gerber, David A. Lilien, Niels F. Nymand, Daniel Steinhage, Olaf Eisen, and Dorthe Dahl-Jensen
The Cryosphere, 19, 1955–1971, https://doi.org/10.5194/tc-19-1955-2025, https://doi.org/10.5194/tc-19-1955-2025, 2025
Short summary
Short summary
This study examines how anisotropic scattering and birefringence affect radar signals in ice sheets. Using data from northeast Greenland, we show that anisotropic scattering – driven by subtle ice crystal orientation changes – dominates the azimuthal power response. We find a strong link between scattering strength, orientation, and stratigraphy. This suggests anisotropic scattering can reveal crystal fabric orientation and differentiate ice units from distinct climatic periods.
Charlotte M. Carter, Steven Franke, Daniela Jansen, Chris R. Stokes, Veit Helm, John Paden, and Olaf Eisen
EGUsphere, https://doi.org/10.5194/egusphere-2025-1743, https://doi.org/10.5194/egusphere-2025-1743, 2025
Short summary
Short summary
The landscapes beneath actively fast-flowing ice in Greenland have not been explored in detail, as digital elevation models do not have a high enough resolution to see these subglacial features. We use swath radar imaging to visualise these landforms at a high resolution, revealing a landscape that would usually be assumed to be indicative of faster ice flow than the current velocities. Interpretation of the landscape also gives an indication of the properties of the bed beneath the ice stream.
Naoko Nagatsuka, Kumiko Goto-Azuma, Kana Nagashima, Koji Fujita, Yuki Komuro, Motohiro Hirabayashi, Jun Ogata, Kaori Fukuda, Yoshimi Ogawa-Tsukagawa, Kyotaro Kitamura, Ayaka Yonekura, Fumio Nakazawa, Yukihiko Onuma, Naoyuki Kurita, Sune Olander Rasmussen, Giulia Sinnl, Trevor James Popp, and Dorthe Dahl-Jensen
EGUsphere, https://doi.org/10.5194/egusphere-2025-1522, https://doi.org/10.5194/egusphere-2025-1522, 2025
Preprint archived
Short summary
Short summary
We present the first continuous records of dust size, composition, and temporal variations in potential sources from the northeastern Greenland ice core (EGRIP) over the past 100 years. Using a multi-proxy provenance approach based on individual particle analysis, we identify the primary dust sources as the Asian (Gobi) and African (Sahara) deserts. Our findings show shifts in their contributions since the 1970s–1980s, highlighting the effectiveness of this approach during low dust periods.
Steven Franke, Daniel Steinhage, Veit Helm, Alexandra M. Zuhr, Julien A. Bodart, Olaf Eisen, and Paul Bons
The Cryosphere, 19, 1153–1180, https://doi.org/10.5194/tc-19-1153-2025, https://doi.org/10.5194/tc-19-1153-2025, 2025
Short summary
Short summary
The study presents internal reflection horizons (IRHs) over an area of 450 000 km² from western Dronning Maud Land, Antarctica, spanning 4.8–91 ka. Using radar and ice core data, nine IRHs were dated and correlated with volcanic events. The data enhance our understanding of the ice sheet's age–depth architecture, accumulation, and dynamics. The findings inform ice flow models and contribute to Antarctic-wide comparisons of IRHs, supporting efforts toward a 3D age–depth ice sheet model.
Chloe A. Brashear, Tyler R. Jones, Valerie Morris, Bruce H. Vaughn, William H. G. Roberts, William B. Skorski, Abigail G. Hughes, Richard Nunn, Sune Olander Rasmussen, Kurt M. Cuffey, Bo M. Vinther, Todd Sowers, Christo Buizert, Vasileios Gkinis, Christian Holme, Mari F. Jensen, Sofia E. Kjellman, Petra M. Langebroek, Florian Mekhaldi, Kevin S. Rozmiarek, Jonathan W. Rheinlænder, Margit H. Simon, Giulia Sinnl, Silje Smith-Johnsen, and James W. C. White
Clim. Past, 21, 529–546, https://doi.org/10.5194/cp-21-529-2025, https://doi.org/10.5194/cp-21-529-2025, 2025
Short summary
Short summary
We use a series of spectral techniques to quantify the strength of high-frequency climate variability in northeastern Greenland to 50 000 ka before present. Importantly, we find that variability consistently decreases hundreds of years prior to Dansgaard–Oeschger warming events. Model simulations suggest a change in North Atlantic sea ice behavior contributed to this pattern, thus providing new information on the conditions which preceded abrupt climate change during the Last Glacial Period.
Paul Dirk Bons, Yuanbang Hu, Maria-Gema Llorens, Steven Franke, Nicolas Stoll, Ilka Weikusat, Julien Wetshoff, and Yu Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2024-3817, https://doi.org/10.5194/egusphere-2024-3817, 2025
Short summary
Short summary
What causes folds in ice layers from the km-scale down to the scale visible in drill core? Classical buckle folding due to variations in viscosity between layers, or the effect of mechanical anisotropy of ice due to an alignment of the crystal-lattice planes? Comparison of power spectra of folds in ice, a biotite schist, and numerical simulations show that folding in ice is due to the mechanical anisotropy, as there is no characteristic fold scale that would result from buckle folding.
Jonathan Ortved Melcher, Sune Halkjær, Peter Ditlevsen, Peter L. Langen, Guido Vettoretti, and Sune Olander Rasmussen
Clim. Past, 21, 115–132, https://doi.org/10.5194/cp-21-115-2025, https://doi.org/10.5194/cp-21-115-2025, 2025
Short summary
Short summary
We introduce a new model that simulates Dansgaard–Oeschger events, dramatic and irregular climate shifts within past ice ages. The model consists of simplified equations inspired by ocean current dynamics. We fine-tune this model to capture the Dansgaard–Oeschger events with unprecedented accuracy, providing deeper insights into past climate patterns. This helps us understand and predict complex climate changes, aiding future climate change resilience efforts.
Frédéric Parrenin, Marie Bouchet, Christo Buizert, Emilie Capron, Ellen Corrick, Russell Drysdale, Kenji Kawamura, Amaëlle Landais, Robert Mulvaney, Ikumi Oyabu, and Sune Olander Rasmussen
Geosci. Model Dev., 17, 8735–8750, https://doi.org/10.5194/gmd-17-8735-2024, https://doi.org/10.5194/gmd-17-8735-2024, 2024
Short summary
Short summary
The Paleochrono-1.1 probabilistic dating model allows users to derive a common and optimized chronology for several paleoclimatic sites from various archives (ice cores, speleothems, marine cores, lake cores, etc.). It combines prior sedimentation scenarios with chronological information such as dated horizons, dated intervals, stratigraphic links and (for ice cores) Δdepth observations. Paleochrono-1.1 is available under an open-source license.
Emma Pearce, Dimitri Zigone, Coen Hofstede, Andreas Fichtner, Joachim Rimpot, Sune Olander Rasmussen, Johannes Freitag, and Olaf Eisen
The Cryosphere, 18, 4917–4932, https://doi.org/10.5194/tc-18-4917-2024, https://doi.org/10.5194/tc-18-4917-2024, 2024
Short summary
Short summary
Our study near EastGRIP camp in Greenland shows varying firn properties by direction (crucial for studying ice stream stability, structure, surface mass balance, and past climate conditions). We used dispersion curve analysis of Love and Rayleigh waves to show firn is nonuniform along and across the flow of an ice stream due to wind patterns, seasonal variability, and the proximity to the edge of the ice stream. This method better informs firn structure, advancing ice stream understanding.
Robert G. Bingham, Julien A. Bodart, Marie G. P. Cavitte, Ailsa Chung, Rebecca J. Sanderson, Johannes C. R. Sutter, Olaf Eisen, Nanna B. Karlsson, Joseph A. MacGregor, Neil Ross, Duncan A. Young, David W. Ashmore, Andreas Born, Winnie Chu, Xiangbin Cui, Reinhard Drews, Steven Franke, Vikram Goel, John W. Goodge, A. Clara J. Henry, Antoine Hermant, Benjamin H. Hills, Nicholas Holschuh, Michelle R. Koutnik, Gwendolyn J.-M. C. Leysinger Vieli, Emma J. Mackie, Elisa Mantelli, Carlos Martín, Felix S. L. Ng, Falk M. Oraschewski, Felipe Napoleoni, Frédéric Parrenin, Sergey V. Popov, Therese Rieckh, Rebecca Schlegel, Dustin M. Schroeder, Martin J. Siegert, Xueyuan Tang, Thomas O. Teisberg, Kate Winter, Shuai Yan, Harry Davis, Christine F. Dow, Tyler J. Fudge, Tom A. Jordan, Bernd Kulessa, Kenichi Matsuoka, Clara J. Nyqvist, Maryam Rahnemoonfar, Matthew R. Siegfried, Shivangini Singh, Verjan Višnjević, Rodrigo Zamora, and Alexandra Zuhr
EGUsphere, https://doi.org/10.5194/egusphere-2024-2593, https://doi.org/10.5194/egusphere-2024-2593, 2024
Short summary
Short summary
The ice sheets covering Antarctica have built up over millenia through successive snowfall events which become buried and preserved as internal surfaces of equal age detectable with ice-penetrating radar. This paper describes an international initiative to work together on this archival data to build a comprehensive 3-D picture of how old the ice is everywhere across Antarctica, and how this will be used to reconstruct past and predict future ice and climate behaviour.
Nicolas Stoll, Ilka Weikusat, Daniela Jansen, Paul Bons, Kyra Darányi, Julien Westhoff, Mária-Gema Llorens, David Wallis, Jan Eichler, Tomotaka Saruya, Tomoyuki Homma, Martyn Drury, Frank Wilhelms, Sepp Kipfstuhl, Dorthe Dahl-Jensen, and Johanna Kerch
EGUsphere, https://doi.org/10.5194/egusphere-2024-2653, https://doi.org/10.5194/egusphere-2024-2653, 2024
Short summary
Short summary
A better understanding of ice flow requires more observational data. The EastGRIP core is the first ice core through an active ice stream. We discuss crystal orientation data to determine the present deformation regimes. A comparison with other deep ice cores shows the unique properties of EastGRIP and that deep ice originates from the Eemian. We further show that the overall plug flow of NEGIS is characterised by many small-scale variations, which remain to be considered in ice-flow models.
Mikkel Langgaard Lauritzen, Anne Munck Solgaard, Nicholas Mossor Rathmann, Bo Møllesøe Vinther, Aslak Grindsted, Brice Noël, Guðfinna Aðalgeirsdóttir, and Christine Schøtt Hvidberg
EGUsphere, https://doi.org/10.5194/egusphere-2024-2223, https://doi.org/10.5194/egusphere-2024-2223, 2024
Short summary
Short summary
We study the Holocene period, which started about 11,700 years ago, through 841 computer simulations to better understand the history of the Greenland Ice Sheet. We accurately match historical surface elevation records, verifying our model. The simulations show that an ice bridge that used to connect the Greenland ice sheet to Canada collapsed around 4,900 years ago and still influences the ice sheet. Over the past 500 years, the Greenland ice sheet has contributed 12 millimeters to sea levels.
Aslak Grinsted, Nicholas Mossor Rathmann, Ruth Mottram, Anne Munck Solgaard, Joachim Mathiesen, and Christine Schøtt Hvidberg
The Cryosphere, 18, 1947–1957, https://doi.org/10.5194/tc-18-1947-2024, https://doi.org/10.5194/tc-18-1947-2024, 2024
Short summary
Short summary
Ice fracture can cause glacier crevassing and calving. These natural hazards can also modulate the flow and evolution of ice sheets. In a new study, we use a new high-resolution dataset to determine a new failure criterion for glacier ice. Surprisingly, the strength of ice depends on the mode of deformation, and this has potential implications for the currently used flow law of ice.
Johannes Lohmann, Jiamei Lin, Bo M. Vinther, Sune O. Rasmussen, and Anders Svensson
Clim. Past, 20, 313–333, https://doi.org/10.5194/cp-20-313-2024, https://doi.org/10.5194/cp-20-313-2024, 2024
Short summary
Short summary
We present the first attempt to constrain the climatic impact of volcanic eruptions with return periods of hundreds of years by the oxygen isotope records of Greenland and Antarctic ice cores covering the last glacial period. A clear multi-annual volcanic cooling signal is seen, but its absolute magnitude is subject to the unknown glacial sensitivity of the proxy. Different proxy signals after eruptions during cooler versus warmer glacial stages may reflect a state-dependent climate response.
Naoko Nagatsuka, Kumiko Goto-Azuma, Koji Fujita, Yuki Komuro, Motohiro Hirabayashi, Jun Ogata, Kaori Fukuda, Yoshimi Ogawa-Tsukagawa, Kyotaro Kitamura, Ayaka Yonekura, Fumio Nakazawa, Yukihiko Onuma, Naoyuki Kurita, Sune Olander Rasmussen, Giulia Sinnl, Trevor James Popp, and Dorthe Dahl-Jensen
EGUsphere, https://doi.org/10.5194/egusphere-2023-1666, https://doi.org/10.5194/egusphere-2023-1666, 2023
Preprint archived
Short summary
Short summary
We present a new high-temporal-resolution record of mineral composition in a northeastern Greenland ice-core (EGRIP) over the past 100 years. The ice core dust composition and its variation differed significantly from a northwestern Greenland ice core, which is likely due to differences in the geological sources of the dust. Our results suggest that the EGRIP ice core dust was constantly supplied from Northern Eurasia, North America, and Asia with minor contribution from Greenland coast.
Sune Olander Rasmussen, Dorthe Dahl-Jensen, Hubertus Fischer, Katrin Fuhrer, Steffen Bo Hansen, Margareta Hansson, Christine S. Hvidberg, Ulf Jonsell, Sepp Kipfstuhl, Urs Ruth, Jakob Schwander, Marie-Louise Siggaard-Andersen, Giulia Sinnl, Jørgen Peder Steffensen, Anders M. Svensson, and Bo M. Vinther
Earth Syst. Sci. Data, 15, 3351–3364, https://doi.org/10.5194/essd-15-3351-2023, https://doi.org/10.5194/essd-15-3351-2023, 2023
Short summary
Short summary
Timescales are essential for interpreting palaeoclimate data. The data series presented here were used for annual-layer identification when constructing the timescales named the Greenland Ice-Core Chronology 2005 (GICC05) and the revised version GICC21. Hopefully, these high-resolution data sets will be useful also for other purposes.
Alice C. Frémand, Peter Fretwell, Julien A. Bodart, Hamish D. Pritchard, Alan Aitken, Jonathan L. Bamber, Robin Bell, Cesidio Bianchi, Robert G. Bingham, Donald D. Blankenship, Gino Casassa, Ginny Catania, Knut Christianson, Howard Conway, Hugh F. J. Corr, Xiangbin Cui, Detlef Damaske, Volkmar Damm, Reinhard Drews, Graeme Eagles, Olaf Eisen, Hannes Eisermann, Fausto Ferraccioli, Elena Field, René Forsberg, Steven Franke, Shuji Fujita, Yonggyu Gim, Vikram Goel, Siva Prasad Gogineni, Jamin Greenbaum, Benjamin Hills, Richard C. A. Hindmarsh, Andrew O. Hoffman, Per Holmlund, Nicholas Holschuh, John W. Holt, Annika N. Horlings, Angelika Humbert, Robert W. Jacobel, Daniela Jansen, Adrian Jenkins, Wilfried Jokat, Tom Jordan, Edward King, Jack Kohler, William Krabill, Mette Kusk Gillespie, Kirsty Langley, Joohan Lee, German Leitchenkov, Carlton Leuschen, Bruce Luyendyk, Joseph MacGregor, Emma MacKie, Kenichi Matsuoka, Mathieu Morlighem, Jérémie Mouginot, Frank O. Nitsche, Yoshifumi Nogi, Ole A. Nost, John Paden, Frank Pattyn, Sergey V. Popov, Eric Rignot, David M. Rippin, Andrés Rivera, Jason Roberts, Neil Ross, Anotonia Ruppel, Dustin M. Schroeder, Martin J. Siegert, Andrew M. Smith, Daniel Steinhage, Michael Studinger, Bo Sun, Ignazio Tabacco, Kirsty Tinto, Stefano Urbini, David Vaughan, Brian C. Welch, Douglas S. Wilson, Duncan A. Young, and Achille Zirizzotti
Earth Syst. Sci. Data, 15, 2695–2710, https://doi.org/10.5194/essd-15-2695-2023, https://doi.org/10.5194/essd-15-2695-2023, 2023
Short summary
Short summary
This paper presents the release of over 60 years of ice thickness, bed elevation, and surface elevation data acquired over Antarctica by the international community. These data are a crucial component of the Antarctic Bedmap initiative which aims to produce a new map and datasets of Antarctic ice thickness and bed topography for the international glaciology and geophysical community.
Giulia Sinnl, Florian Adolphi, Marcus Christl, Kees C. Welten, Thomas Woodruff, Marc Caffee, Anders Svensson, Raimund Muscheler, and Sune Olander Rasmussen
Clim. Past, 19, 1153–1175, https://doi.org/10.5194/cp-19-1153-2023, https://doi.org/10.5194/cp-19-1153-2023, 2023
Short summary
Short summary
The record of past climate is preserved by several archives from different regions, such as ice cores from Greenland or Antarctica or speleothems from caves such as the Hulu Cave in China. In this study, these archives are aligned by taking advantage of the globally synchronous production of cosmogenic radionuclides. This produces a new perspective on the global climate in the period between 20 000 and 25 000 years ago.
Ole Zeising, Tamara Annina Gerber, Olaf Eisen, M. Reza Ershadi, Nicolas Stoll, Ilka Weikusat, and Angelika Humbert
The Cryosphere, 17, 1097–1105, https://doi.org/10.5194/tc-17-1097-2023, https://doi.org/10.5194/tc-17-1097-2023, 2023
Short summary
Short summary
The flow of glaciers and ice streams is influenced by crystal fabric orientation. Besides sparse ice cores, these can be investigated by radar measurements. Here, we present an improved method which allows us to infer the horizontal fabric asymmetry using polarimetric phase-sensitive radar data. A validation of the method on a deep ice core from the Greenland Ice Sheet shows an excellent agreement, which is a large improvement over previously used methods.
Niccolò Maffezzoli, Eliza Cook, Willem G. M. van der Bilt, Eivind N. Støren, Daniela Festi, Florian Muthreich, Alistair W. R. Seddon, François Burgay, Giovanni Baccolo, Amalie R. F. Mygind, Troels Petersen, Andrea Spolaor, Sebastiano Vascon, Marcello Pelillo, Patrizia Ferretti, Rafael S. dos Reis, Jefferson C. Simões, Yuval Ronen, Barbara Delmonte, Marco Viccaro, Jørgen Peder Steffensen, Dorthe Dahl-Jensen, Kerim H. Nisancioglu, and Carlo Barbante
The Cryosphere, 17, 539–565, https://doi.org/10.5194/tc-17-539-2023, https://doi.org/10.5194/tc-17-539-2023, 2023
Short summary
Short summary
Multiple lines of research in ice core science are limited by manually intensive and time-consuming optical microscopy investigations for the detection of insoluble particles, from pollen grains to volcanic shards. To help overcome these limitations and support researchers, we present a novel methodology for the identification and autonomous classification of ice core insoluble particles based on flow image microscopy and neural networks.
Steven Franke, Alfons Eckstaller, Tim Heitland, Thomas Schaefer, and Jölund Asseng
Polarforschung, 90, 65–79, https://doi.org/10.5194/polf-90-65-2022, https://doi.org/10.5194/polf-90-65-2022, 2022
Short summary
Short summary
For over 45 years, teams composed of scientists, technicians, doctors, and cooks have been wintering in Antarctica in the service of German Antarctic research. They thus form a cornerstone of long-term scientific measurements in this remote and unique place with regard to future scientific investigations. In this article, we highlight the research being conducted at the permanently crewed Neumayer Station III and its predecessors and the role of the overwinterers in this research endeavour.
Vjeran Višnjević, Reinhard Drews, Clemens Schannwell, Inka Koch, Steven Franke, Daniela Jansen, and Olaf Eisen
The Cryosphere, 16, 4763–4777, https://doi.org/10.5194/tc-16-4763-2022, https://doi.org/10.5194/tc-16-4763-2022, 2022
Short summary
Short summary
We present a simple way to model the internal layers of an ice shelf and apply the method to the Roi Baudouin Ice Shelf in East Antarctica. Modeled results are compared to measurements obtained by radar. We distinguish between ice directly formed on the shelf and ice transported from the ice sheet, and we map the spatial changes in the volume of the locally accumulated ice. In this context, we discuss the sensitivity of the ice shelf to future changes in surface accumulation and basal melt.
Alfons Eckstaller, Jölund Asseng, Erich Lippmann, and Steven Franke
Geosci. Instrum. Method. Data Syst., 11, 235–245, https://doi.org/10.5194/gi-11-235-2022, https://doi.org/10.5194/gi-11-235-2022, 2022
Short summary
Short summary
We present a mobile and self-sufficient seismometer station concept for operation in polar regions. The energy supply can be adapted as required using the modular cascading of battery boxes, wind generators, solar cells, or backup batteries, which enables optimum use of limited resources. Our system concept is not limited to the applications using seismological stations. It is a suitable system for managing the power supply of all types of self-sufficient measuring systems in polar regions.
Falk M. Oraschewski and Aslak Grinsted
The Cryosphere, 16, 2683–2700, https://doi.org/10.5194/tc-16-2683-2022, https://doi.org/10.5194/tc-16-2683-2022, 2022
Short summary
Short summary
Old snow (denoted as firn) accumulates in the interior of ice sheets and gets densified into glacial ice. Typically, this densification is assumed to only depend on temperature and accumulation rate. However, it has been observed that stretching of the firn by horizontal flow also enhances this process. Here, we show how to include this effect in classical firn models. With the model we confirm that softening of the firn controls firn densification in areas with strong horizontal stretching.
Giulia Sinnl, Mai Winstrup, Tobias Erhardt, Eliza Cook, Camilla Marie Jensen, Anders Svensson, Bo Møllesøe Vinther, Raimund Muscheler, and Sune Olander Rasmussen
Clim. Past, 18, 1125–1150, https://doi.org/10.5194/cp-18-1125-2022, https://doi.org/10.5194/cp-18-1125-2022, 2022
Short summary
Short summary
A new Greenland ice-core timescale, covering the last 3800 years, was produced using the machine learning algorithm StratiCounter. We synchronized the ice cores using volcanic eruptions and wildfires. We compared the new timescale to the tree-ring timescale, finding good alignment both between the common signatures of volcanic eruptions and of solar activity. Our Greenlandic timescales is safe to use for the Late Holocene, provided one uses our uncertainty estimate.
Julien Westhoff, Giulia Sinnl, Anders Svensson, Johannes Freitag, Helle Astrid Kjær, Paul Vallelonga, Bo Vinther, Sepp Kipfstuhl, Dorthe Dahl-Jensen, and Ilka Weikusat
Clim. Past, 18, 1011–1034, https://doi.org/10.5194/cp-18-1011-2022, https://doi.org/10.5194/cp-18-1011-2022, 2022
Short summary
Short summary
We present a melt event record from an ice core from central Greenland, which covers the past 10 000 years. Our record displays warm summer events, which can be used to enhance our understanding of the past climate. We compare our data to anomalies in tree ring width, which also represents summer temperatures, and find a good correlation. Furthermore, we investigate an outstandingly warm event in the year 986 AD or 991 AD, which has not been analyzed before.
Ann-Sofie Priergaard Zinck and Aslak Grinsted
The Cryosphere, 16, 1399–1407, https://doi.org/10.5194/tc-16-1399-2022, https://doi.org/10.5194/tc-16-1399-2022, 2022
Short summary
Short summary
The Müller Ice Cap will soon set the scene for a new drilling project. To obtain an ice core with stratified layers and a good time resolution, thickness estimates are necessary for the planning. Here we present a new and fast method of estimating ice thicknesses from sparse data and compare it to an existing ice flow model. We find that the new semi-empirical method is insensitive to mass balance, is computationally fast, and provides good fits when compared to radar measurements.
Jiamei Lin, Anders Svensson, Christine S. Hvidberg, Johannes Lohmann, Steffen Kristiansen, Dorthe Dahl-Jensen, Jørgen Peder Steffensen, Sune Olander Rasmussen, Eliza Cook, Helle Astrid Kjær, Bo M. Vinther, Hubertus Fischer, Thomas Stocker, Michael Sigl, Matthias Bigler, Mirko Severi, Rita Traversi, and Robert Mulvaney
Clim. Past, 18, 485–506, https://doi.org/10.5194/cp-18-485-2022, https://doi.org/10.5194/cp-18-485-2022, 2022
Short summary
Short summary
We employ acidity records from Greenland and Antarctic ice cores to estimate the emission strength, frequency and climatic forcing for large volcanic eruptions from the last half of the last glacial period. A total of 25 volcanic eruptions are found to be larger than any eruption in the last 2500 years, and we identify more eruptions than obtained from geological evidence. Towards the end of the glacial period, there is a notable increase in volcanic activity observed for Greenland.
Steven Franke, Daniela Jansen, Tobias Binder, John D. Paden, Nils Dörr, Tamara A. Gerber, Heinrich Miller, Dorthe Dahl-Jensen, Veit Helm, Daniel Steinhage, Ilka Weikusat, Frank Wilhelms, and Olaf Eisen
Earth Syst. Sci. Data, 14, 763–779, https://doi.org/10.5194/essd-14-763-2022, https://doi.org/10.5194/essd-14-763-2022, 2022
Short summary
Short summary
The Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland. In order to better understand the past and future dynamics of the NEGIS, we present a high-resolution airborne radar data set (EGRIP-NOR-2018) for the onset region of the NEGIS. The survey area is centered at the location of the drill site of the East Greenland Ice-Core Project (EastGRIP), and radar profiles cover both shear margins and are aligned parallel to several flow lines.
Paul D. Bons, Tamara de Riese, Steven Franke, Maria-Gema Llorens, Till Sachau, Nicolas Stoll, Ilka Weikusat, Julien Westhoff, and Yu Zhang
The Cryosphere, 15, 2251–2254, https://doi.org/10.5194/tc-15-2251-2021, https://doi.org/10.5194/tc-15-2251-2021, 2021
Short summary
Short summary
The modelling of Smith-Johnson et al. (The Cryosphere, 14, 841–854, 2020) suggests that a very large heat flux of more than 10 times the usual geothermal heat flux is required to have initiated or to control the huge Northeast Greenland Ice Stream. Our comparison with known hotspots, such as Iceland and Yellowstone, shows that such an exceptional heat flux would be unique in the world and is incompatible with known geological processes that can raise the heat flux.
David A. Lilien, Daniel Steinhage, Drew Taylor, Frédéric Parrenin, Catherine Ritz, Robert Mulvaney, Carlos Martín, Jie-Bang Yan, Charles O'Neill, Massimo Frezzotti, Heinrich Miller, Prasad Gogineni, Dorthe Dahl-Jensen, and Olaf Eisen
The Cryosphere, 15, 1881–1888, https://doi.org/10.5194/tc-15-1881-2021, https://doi.org/10.5194/tc-15-1881-2021, 2021
Short summary
Short summary
We collected radar data between EDC, an ice core spanning ~800 000 years, and BELDC, the site chosen for a new
oldest icecore at nearby Little Dome C. These data allow us to identify 50 % older internal horizons than previously traced in the area. We fit a model to the ages of those horizons at BELDC to determine the age of deep ice there. We find that there is likely to be 1.5 Myr old ice ~265 m above the bed, with sufficient resolution to preserve desired climatic information.
Aslak Grinsted and Jens Hesselbjerg Christensen
Ocean Sci., 17, 181–186, https://doi.org/10.5194/os-17-181-2021, https://doi.org/10.5194/os-17-181-2021, 2021
Short summary
Short summary
As we warm our planet, oceans expand, ice on land melts, and sea levels rise. On century timescales, we find that the sea level response to warming can be characterized by a single metric: the transient sea level sensitivity. Historical sea level exhibits substantially higher sensitivity than model-based estimates of future climates in authoritative climate assessments, implying recent projections could well underestimate the likely sea level rise by the end of this century.
Helle Astrid Kjær, Patrick Zens, Ross Edwards, Martin Olesen, Ruth Mottram, Gabriel Lewis, Christian Terkelsen Holme, Samuel Black, Kasper Holst Lund, Mikkel Schmidt, Dorthe Dahl-Jensen, Bo Vinther, Anders Svensson, Nanna Karlsson, Jason E. Box, Sepp Kipfstuhl, and Paul Vallelonga
The Cryosphere Discuss., https://doi.org/10.5194/tc-2020-337, https://doi.org/10.5194/tc-2020-337, 2021
Manuscript not accepted for further review
Short summary
Short summary
We have reconstructed accumulation in 6 firn cores and 8 snow cores in Northern Greenland and compared with a regional Climate model over Greenland. We find the model underestimate precipitation especially in north-eastern part of the ice cap- an important finding if aiming to reconstruct surface mass balance.
Temperatures at 10 meters depth at 6 sites in Greenland were also determined and show a significant warming since the 1990's of 0.9 to 2.5 °C.
Ikumi Oyabu, Kenji Kawamura, Kyotaro Kitamura, Remi Dallmayr, Akihiro Kitamura, Chikako Sawada, Jeffrey P. Severinghaus, Ross Beaudette, Anaïs Orsi, Satoshi Sugawara, Shigeyuki Ishidoya, Dorthe Dahl-Jensen, Kumiko Goto-Azuma, Shuji Aoki, and Takakiyo Nakazawa
Atmos. Meas. Tech., 13, 6703–6731, https://doi.org/10.5194/amt-13-6703-2020, https://doi.org/10.5194/amt-13-6703-2020, 2020
Short summary
Short summary
Air in polar ice cores provides information on past atmosphere and climate. We present a new method for simultaneously measuring eight gases (CH4, N2O and CO2 concentrations; isotopic ratios of N2 and O2; elemental ratios between N2, O2 and Ar; and total air content) from single ice-core samples with high precision.
Seyedhamidreza Mojtabavi, Frank Wilhelms, Eliza Cook, Siwan M. Davies, Giulia Sinnl, Mathias Skov Jensen, Dorthe Dahl-Jensen, Anders Svensson, Bo M. Vinther, Sepp Kipfstuhl, Gwydion Jones, Nanna B. Karlsson, Sergio Henrique Faria, Vasileios Gkinis, Helle Astrid Kjær, Tobias Erhardt, Sarah M. P. Berben, Kerim H. Nisancioglu, Iben Koldtoft, and Sune Olander Rasmussen
Clim. Past, 16, 2359–2380, https://doi.org/10.5194/cp-16-2359-2020, https://doi.org/10.5194/cp-16-2359-2020, 2020
Short summary
Short summary
We present a first chronology for the East Greenland Ice-core Project (EGRIP) over the Holocene and last glacial termination. After field measurements and processing of the ice-core data, the GICC05 timescale is transferred from the NGRIP core to the EGRIP core by means of matching volcanic events and common patterns (381 match points) in the ECM and DEP records. The new timescale is named GICC05-EGRIP-1 and extends back to around 15 kyr b2k.
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, https://doi.org/10.5194/tc-14-3487-2020, https://doi.org/10.5194/tc-14-3487-2020, 2020
Short summary
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.
James E. Lee, Edward J. Brook, Nancy A. N. Bertler, Christo Buizert, Troy Baisden, Thomas Blunier, V. Gabriela Ciobanu, Howard Conway, Dorthe Dahl-Jensen, Tyler J. Fudge, Richard Hindmarsh, Elizabeth D. Keller, Frédéric Parrenin, Jeffrey P. Severinghaus, Paul Vallelonga, Edwin D. Waddington, and Mai Winstrup
Clim. Past, 16, 1691–1713, https://doi.org/10.5194/cp-16-1691-2020, https://doi.org/10.5194/cp-16-1691-2020, 2020
Short summary
Short summary
The Roosevelt Island ice core was drilled to investigate climate from the eastern Ross Sea, West Antarctica. We describe the ice age-scale and gas age-scale of the ice core for 0–763 m (83 000 years BP). Old ice near the bottom of the core implies the ice dome existed throughout the last glacial period and that ice streaming was active in the region. Variations in methane, similar to those used as evidence of early human influence on climate, were observed prior to significant human populations.
Cited articles
Ageta, Y., Azuma, N., Fujii, Y., Fujino, K., Fujita, S., Furukawa, T., Hondoh, T., Kameda, T., Kamiyama, K., Katagiri, K., Kawada, K., Kawamura, T., Kobayashi, S., Mae, S., Maeno, H., Miyahara, T., Motoyama, H., Nakayama, Y., Naruse, R., Nishio, F., Saitoh, K., Saitoh, T., Shimbori, K., Shiraiwa, T., Shoji, H., Takahashi, A., Takahashi, S., Tanaka, Y., Yokoyama, K., and Watanabe, O.: Deep ice-core drilling at Dome Fuji and glaciological studies in east Dronning Maud Land, Antarctica, Ann. Glaciol., 27, 333–337, https://doi.org/10.3189/1998aog27-1-333-337, 1998. a
Aizen, V. B., Aizen, E. M., Joswiak, D. R., Fujita, K., Takeuchi, N., and Nikitin, S. A.: Climatic and atmospheric circulation pattern variability from ice-core isotope/geochemistry records (Altai, Tien Shan and Tibet), Ann. Glaciol., 43, 49–60, https://doi.org/10.3189/172756406781812078, 2006. a
Alley, R. B., Bolzan, J. F., and Whillans, I. M.: Polar firn densification and grain growth, Ann. Glaciol., 3, 7–11, https://doi.org/10.3189/S0260305500002433, 1982. a
Alley, R. B., Meese, D. A., Shuman, C. A., Gow, A. J., Taylor, K. C., Grootes, P. M., White, J. W., Ram, M., Waddington, E. D., Mayewski, P. A., and Zielinski, G. A.: Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event, Nature, 362, 527–529, https://doi.org/10.1038/362527a0, 1993. a
Alley, R. B., Pollard, D., Parizek, B. R., Anandakrishnan, S., Pourpoint, M., Stevens, N. T., MacGregor, J. A., Christianson, K., Muto, A., and Holschuh, N.: Possible Role for Tectonics in the Evolving Stability of the Greenland Ice Sheet, J. Geophys. Res.-Earth, 124, 97–115, https://doi.org/10.1029/2018JF004714, 2019. a, b
Andersen, J. K., Kusk, A., Boncori, J. P. M., Hvidberg, C. S., and Grinsted, A.: Improved ice velocity measurements with Sentinel-1 TOPS interferometry, Remote Sens.-Basel, 12, 1–22, https://doi.org/10.3390/rs12122014, 2020. a, b, c
Andersen, K. K., Azuma, N., Barnola, J. M., Bigler, M., Biscaye, P., Caillon, N., Chappellaz, J., Clausen, H. B., Dahl-Jensen, D., Fischer, H., Flückiger, J., Fritzsche, D., Fujii, Y., Goto-Azuma, K., Grønvold, K., Gundestrup, N. S., Hansson, M., Huber, C., Hvidberg, C. S., Johnsen, S. J., Jonsell, U., Jouzel, J., Kipfstuhl, S., Landais, A., Leuenberger, M., Lorrain, R., Masson-Delmotte, V., Miller, H., Motoyama, H., Narita, H., Popp, T., Rasmussen, S. O., Raynaud, D., Rothlisberger, R., Ruth, U., Samyn, D., Schwander, J., Shoji, H., Siggard-Andersen, M. L., Steffensen, J. P., Stocker, T., Sveinbjörnsdóttir, A. E., Svensson, A., Takata, M., Tison, J. L., Thorsteinsson, T., Watanabe, O., Wilhelms, F., and White, J. W.: High-resolution record of Northern Hemisphere climate extending into the last interglacial period, Nature, 431, 147–151, https://doi.org/10.1038/nature02805, 2004. a, b, c
Andersen, K. K., Svensson, A., Johnsen, S. J., Rasmussen, S. O., Bigler, M., Röthlisberger, R., Ruth, U., Siggaard-Andersen, M. L., Peder Steffensen, J., Dahl-Jensen, D., Vinther, B. M., and Clausen, H. B.: The Greenland Ice Core Chronology 2005, 15–42 ka. Part 1: constructing the time scale, Quaternary Sci. Rev., 25, 3246–3257, https://doi.org/10.1016/j.quascirev.2006.08.002, 2006. a
Aschwanden, A., Fahnestock, M. A., and Truffer, M.: Complex Greenland outlet glacier flow captured, Nat. Commun., 7, 1–8, https://doi.org/10.1038/ncomms10524, 2016. a
Barbante, C., Barnola, J. M., Becagli, S., Beer, J., Bigler, M., Boutron, C., Blunier, T., Castellano, E., Cattani, O., Chappellaz, J., Dahl-Jensen, D., Debret, M., Delmonte, B., Dick, D., Falourd, S., Faria, S., Federer, U., Fischer, H., Freitag, J., Frenzel, A., Fritzsche, D., Fundel, F., Gabrielli, P., Gaspari, V., Gersonde, R., Graf, W., Grigoriev, D., Hamann, I., Hansson, M., Hoffmann, G., Hutterli, M. A., Huybrechts, P., Isaksson, E., Johnsen, S., Jouzel, J., Kaczmarska, M., Karlin, T., Kaufmann, P., Kipfstuhl, S., Kohno, M., Lambert, F., Lambrecht, A., Lambrecht, A., Landais, A., Lawer, G., Leuenberger, M., Littot, G., Loulergue, L., Lüthi, D., Maggi, V., Marino, F., Masson-Delmotte, V., Meyer, H., Miller, H., Mulvaney, R., Narcisi, B., Oerlemans, J., Oerter, H., Parrenin, F., Petit, J. R., Raisbeck, G., Raynaud, D., Röthlisberger, R., Ruth, U., Rybak, O., Severi, M., Schmitt, J., Schwander, J., Siegenthaler, U., Siggaard-Andersen, M. L., Spahni, R., Steffensen, J. P., Stenni, B., Stocker, T. F., Tison, J. L., Traversi, R., Udisti, R., Valero-Delgado, F., Van Den Broeke, M. R., Van De Wal, R. S., Wagenbach, D., Wegner, A., Weiler, K., Wilhelms, F., Winther, J. G., and Wolff, E.: One-to-one coupling of glacial climate variability in Greenland and Antarctica, Nature, 444, 195–198, https://doi.org/10.1038/nature05301, 2006. a
Beyer, S., Kleiner, T., Aizinger, V., Rückamp, M., and Humbert, A.: A confined–unconfined aquifer model for subglacial hydrology and its application to the Northeast Greenland Ice Stream, The Cryosphere, 12, 3931–3947, https://doi.org/10.5194/tc-12-3931-2018, 2018. a
Bons, P. D., Jansen, D., Mundel, F., Bauer, C. C., Binder, T., Eisen, O., Jessell, M. W., Llorens, M. G., Steinbach, F., Steinhage, D., and Weikusat, I.: Converging flow and anisotropy cause large-scale folding in Greenland's ice sheet, Nat. Commun., 7, 1–6, https://doi.org/10.1038/ncomms11427, 2016. a
Bons, P. D., de Riese, T., Franke, S., Llorens, M.-G., Sachau, T., Stoll, N., Weikusat, I., Westhoff, J., and Zhang, Y.: Comment on “Exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream” by Smith-Johnsen et al. (2020), The Cryosphere, 15, 2251–2254, https://doi.org/10.5194/tc-15-2251-2021, 2021. a, b
Buchardt, S. L. and Dahl-Jensen, D.: Estimating the basal melt rate at NorthGRIP using a Monte Carlo technique, Ann. Glaciol., 45, 137–142, https://doi.org/10.3189/172756407782282435, 2007. a, b
Burgess, E. W., Forster, R. R., Box, J. E., Mosley-Thompson, E., Bromwich, D. H., Bales, R. C., and Smith, L. C.: A spatially calibrated model of annual accumulation rate on the Greenland Ice Sheet (1958–2007), J. Geophys. Res.-Earth, 115, 1–14, https://doi.org/10.1029/2009JF001293, 2010. a
Byers, K. J., Harish, A. R., Seguin, S. A., Leuschen, C. J., Rodriguez-Morales, F., Paden, J., Arnold, E. J., and Hale, R. D.: A modified wideband dipole antenna for an airborne VHF ice-penetrating radar, IEEE T. Instrum. Meas., 61, 1435–1444, https://doi.org/10.1109/TIM.2011.2181780, 2012. a
Catania, G., Hulbe, C., and Conway, H.: Grounding-line basal melt rates determined using radar-derived internal stratigraphy, J. Glaciol., 56, 545–554, https://doi.org/10.3189/002214310792447842, 2010. a
Christianson, K., Parizek, B. R., Alley, R. B., Horgan, H. J., Jacobel, R. W., Anandakrishnan, S., Keisling, B. A., Craig, B. D., and Muto, A.: Ice sheet grounding zone stabilization due to till compaction, Geophys. Res. Lett., 40, 5406–5411, https://doi.org/10.1002/2013GL057447, 2013. a, b
Christianson, K., Peters, L. E., Alley, R. B., Anandakrishnan, S., Jacobel, R. W., Riverman, K. L., Muto, A., and Keisling, B. A.: Dilatant till facilitates ice-stream flow in northeast Greenland, Earth Planet. Sc. Lett., 401, 57–69, https://doi.org/10.1016/j.epsl.2014.05.060, 2014. a, b
Crameri, F.: Scientific colour maps, Zenodo [code], https://doi.org/10.5281/zenodo.4153113, 2020. a
Crameri, F., Shephard, G. E., and Heron, P. J.: The misuse of colour in science communication, Nat. Commun., 11, 1–10, https://doi.org/10.1038/s41467-020-19160-7, 2020. a
Cuffey, K. M. and Clow, G. D.: Temperature, accumulation, and ice sheet elevation in central Greenland through the last deglacial transition, J. Geophys. Res.-Oceans, 102, 26383–26396, https://doi.org/10.1029/96JC03981, 1997. a, b
Cuffey, K. M. and Paterson, W. S. B.: The physics of glaciers, Butterworth-Heinemann/Elsevier, Amsterdam, 4th Edn., 2010. a
Dahl-Jensen, D., Johnsen, S. J., Hammer, C. U., Clausen, H. B., and Jouzel, J.: Past Accumulation rates derived from observed annual layers in the GRIP ice core from Summit, Central Greenland, Ice in the Climate System, 112, 517–532, https://doi.org/10.1007/978-3-642-85016-5_29, 1993. a, b
Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G. D., Johnsen, S. J., Hansen, A. W., and Balling, N.: Past temperatures directly from the Greenland ice sheet, Science, 282, 268–271, https://doi.org/10.1126/science.282.5387.268, 1998. a
Dahl-Jensen, D., Gundestrup, N., Gogineni, S. P., and Miller, H.: Basal melt at NorthGRIP modeled from borehole, ice-core and radio-echo sounder observations, Ann. Glaciol., 37, 207–212, https://doi.org/10.3189/172756403781815492, 2003. a
Dansgaard, W.: Stable isotopes in precipitation, Tellus, 16, 436–468, https://doi.org/10.3402/tellusa.v16i4.8993, 1964. a
Dansgaard, W., Clausen, H. B., Gundestrup, N., Hammer, C. U., Johnsen, S. F., Kristinsdottir, P. M., and Reeh, N.: A new Greenland deep ice core, Science, 218, 1273–1277, https://doi.org/10.1126/science.218.4579.1273, 1982. a, b
Delaygue, G. and Bard, E.: An Antarctic view of Beryllium-10 and solar activity for the past millennium, Clim. Dynam., 36, 2201–2218, https://doi.org/10.1007/s00382-010-0795-1, 2011. a
Eicher, O., Baumgartner, M., Schilt, A., Schmitt, J., Schwander, J., Stocker, T. F., and Fischer, H.: Climatic and insolation control on the high-resolution total air content in the NGRIP ice core, Clim. Past, 12, 1979–1993, https://doi.org/10.5194/cp-12-1979-2016, 2016. a
Eisen, O., Wilhelms, F., Steinhage, D., and Schwander, J.: Improved method to determine radio-echo sounding reflector depths from ice-core profiles of permittivity and conductivity, J. Glaciol., 52, 299–310, https://doi.org/10.3189/172756506781828674, 2006. a
Fahnestock, M., Bindschadler, R., Kwok, R., and Jezek, K.: Greenland Ice Sheet surface properties and ice dynamics from ERS-1 SAR imagery, Science, 262, 1530-1534, https://doi.org/10.1126/science.262.5139.1530, 1993. a, b
Fahnestock, M., Abdalati, W., Joughin, I., Brozena, J., and Gogineni, P.: High geothermal heat flow, basal melt, and the origin of rapid ice flow in central Greenland, Science, 294, 2338–2342, https://doi.org/10.1126/science.1065370, 2001. a, b, c, d
Finkel, R. C. and Nishiizumi, K.: Beryllium 10 concentrations in the Greenland Ice Sheet Project 2 ice core from 3–40 ka, J. Geophys. Res.-Oceans, 102, 26699–26706, https://doi.org/10.1029/97JC01282, 1997. a
Franke, S., Jansen, D., Binder, T., Dörr, N., Helm, V., Paden, J., Steinhage, D., and Eisen, O.: Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream, Ann. Glaciol., 61, 143–153, https://doi.org/10.1017/aog.2020.12, 2020. a
Franke, S., Jansen, D., Beyer, S., Neckel, N., Binder, T., Paden, J., and Eisen, O.: Complex basal conditions and their influence on ice flow at the onset of the Northeast Greenland Ice Stream, J. Geophys. Res.-Earth, 126, e2020JF005689, https://doi.org/10.1029/2020jf005689, 2021a. a, b
Franke, S., Jansen, D., Binder, T., Paden, J. D., Dörr, N., Gerber, T., Miller, H., Dahl-Jensen, D., Helm, V., Steinhage, D., Weikusat, I., Wilhelms, F., and Eisen, O.: Airborne ultra-wideband radar sounding over the shear margins and along flow lines at the onset region of the Northeast Greenland Ice Stream, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2021-91, in review, 2021b. a, b, c, d, e
Fudge, T. J., Steig, E. J., Markle, B. R., Schoenemann, S. W., Ding, Q., Taylor, K. C., McConnell, J. R., Brook, E. J., Sowers, T., White, J. W., Alley, R. B., Cheng, H., Clow, G. D., Cole-Dai, J., Conway, H., Cuffey, K. M., Edwards, J. S., Lawrence Edwards, R., Edwards, R., Fegyveresi, J. M., Ferris, D., Fitzpatrick, J. J., Johnson, J., Hargreaves, G., Lee, J. E., Maselli, O. J., Mason, W., McGwire, K. C., Mitchell, L. E., Mortensen, N., Neff, P., Orsi, A. J., Popp, T. J., Schauer, A. J., Severinghaus, J. P., Sigl, M., Spencer, M. K., Vaughn, B. H., Voigt, D. E., Waddington, E. D., Wang, X., and Wong, G. J.: Onset of deglacial warming in West Antarctica driven by local orbital forcing, Nature, 500, 440–444, https://doi.org/10.1038/nature12376, 2013. a
Fudge, T. J., Lilien, D. A., Koutnik, M., Conway, H., Stevens, C. M., Waddington, E. D., Steig, E. J., Schauer, A. J., and Holschuh, N.: Advection and non-climate impacts on the South Pole Ice Core, Clim. Past, 16, 819–832, https://doi.org/10.5194/cp-16-819-2020, 2020. a, b
Gardner, A. S., Fahnestock, M. A., and Scambos, T. A.: ITS_LIVE Regional Glacier and Ice Sheet Surface Velocities, National Snow and Ice Data Center [data set], https://doi.org/10.5067/6II6VW8LLWJ7, 2020. a
Gogineni, S., Tammana, D., Braaten, D., Leuschen, C., Akins, T., Legarsky, J., Kanagaratnam, P., Stiles, J., Allen, C., and Jezek, K.: Coherent radar ice thickness measurements over the Greenland ice sheet, J. Geophys. Res.-Atmos., 106, 33761–33772, https://doi.org/10.1029/2001JD900183, 2001. a
Gow, A. J., Ueda, H. T., and Garfield, D. E.: Antarctic ice sheet: Preliminary results of first core hole to bedrock, Science, 161, 1011–1013, https://doi.org/10.1126/science.161.3845.1011, 1968. a
Greene, C. A., Gwyther, D. E., and Blankenship, D. D.: Antarctic Mapping Tools for Matlab, Comput. Geosci., 104, 151–157, https://doi.org/10.1016/j.cageo.2016.08.003, 2017. a
Grinsted, A. and Dahl-Jensen, D.: A Monte Carlo-tuned model of the flow in the NorthGRIP area, Ann. Glaciol., 35, 527–530, https://doi.org/10.3189/172756402781817130, 2002. a, b, c, d
Hammer, C. U.: Acidity of Polar Ice Cores in Relation to Absolute Dating, Past Volcanism, and Radio–Echoes, J. Glaciol., 25, 359–372, https://doi.org/10.3189/s0022143000015227, 1980. a
Harrison, C. H.: Radio Echo Sounding of Horizontal Layers in Ice, J. Glaciol., 12, 383–397, https://doi.org/10.3189/s0022143000031804, 1973. a
Herron, M. M. and Langway, C. C.: Firn densification: an empirical model, J. Glaciol., 25, 373–385, https://doi.org/10.1017/S0022143000015239, 1980. a
Holschuh, N., Christianson, K., and Anandakrishnan, S.: Power loss in dipping internal reflectors, imaged using ice-penetrating radar, Ann. Glaciol., 55, 49–56, https://doi.org/10.3189/2014AoG67A005, 2014. a
Holschuh, N., Lilien, D. A., and Christianson, K.: Thermal Weakening, Convergent Flow, and Vertical Heat Transport in the Northeast Greenland Ice Stream Shear Margins, Geophys. Res. Lett., 46, 8184–8193, https://doi.org/10.1029/2019GL083436, 2019. a
Hvidberg, C. S., Keller, K., Gundestrup, N. S., Tscherning, C. C., and Forsberg, R.: Mass balance and surface movement of the Greenland ice sheet at summit, Central Greenland, Geophys. Res. Lett., 24, 2307–2310, https://doi.org/10.1029/97GL02280, 1997. a
Hvidberg, C. S., Grinsted, A., Dahl-Jensen, D., Khan, S. A., Kusk, A., Andersen, J. K., Neckel, N., Solgaard, A., Karlsson, N. B., Kjær, H. A., and Vallelonga, P.: Surface velocity of the Northeast Greenland Ice Stream (NEGIS): assessment of interior velocities derived from satellite data by GPS, The Cryosphere, 14, 3487–3502, https://doi.org/10.5194/tc-14-3487-2020, 2020. a, b
Jacobel, R. W., Gades, A. M., Gottschling, D. L., Hodge, S. M., and Wright, D. L.: Interpretation of radar-detected internal layer folding in West Antarctic ice streams, J. Glaciol., 39, 528–537, https://doi.org/10.1017/s0022143000016427, 1993. a
Jansen, D., Franke, S., Binder, T., Paden, J. D., Steinhage, D., Helm, V., and Eisen, O.: AWI UWB radar data along ice flow upstream of the EGRIP drill site at the onset region of the Northeast Greenland Ice Stream, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.914258, 2020. a, b, c
Johnsen, S. J., Clausen, H. B., Dansgaard, W., Fuhrer, K., Gundestrup, N., Hammer, C. U., Iversen, P., Jouzel, J., Stauffer, B., and Steffensen, J. P.: Irregular glacial interstadials recorded in a new Greenland ice core, Nature, 359, 311–313, https://doi.org/10.1038/359311a0, 1992. a
Joughin, I., Fahnestock, M., MacAyeal, D., Bamber, J. L., and Gogineni, P.: Observation and analysis of ice flow in the largest Greenland ice stream, J. Geophys. Res.-Atmos., 106, 34021–34034, https://doi.org/10.1029/2001JD900087, 2001. a
Jouzel, J., Alley, R. B., Cuffey, K. M., Dansgaard, W., Grootes, P., Hoffmann, G., Johnsen, S. J., Koster, R. D., Peel, D., Shuman, C. A., Stievenard, M., Stuiver, M., and White, J.: Validity of the temperature reconstruction from water isotopes in ice cores, J. Geophys. Res.-Oceans, 102, 26471–26487, https://doi.org/10.1029/97JC01283, 1997. a
Keisling, B. A., Christianson, K., Alley, R. B., Peters, L. E., Christian, J. E., Anandakrishnan, S., Riverman, K. L., Muto, A., and Jacobel, R. W.: Basal conditions and ice dynamics inferred from radar-derived internal stratigraphy of the northeast Greenland ice stream, Ann. Glaciol., 55, 127–137, https://doi.org/10.3189/2014AoG67A090, 2014. a, b, c, d, e, f, g
Khan, S. A., Kjær, K. H., Bevis, M., Bamber, J. L., Wahr, J., Kjeldsen, K. K., Bjørk, A. A., Korsgaard, N. J., Stearns, L. A., Van Den Broeke, M. R., Liu, L., Larsen, N. K., and Muresan, I. S.: Sustained mass loss of the northeast Greenland ice sheet triggered by regional warming, Nat. Clim. Change, 4, 292–299, https://doi.org/10.1038/nclimate2161, 2014. a, b, c
Lawver, L. A. and Müller, R. D.: Iceland hotspot track, Geology, 22, 311–314, https://doi.org/10.1130/0091-7613(1994)022<0311:IHT>2.3.CO;2, 1994. a
Letréguilly, A., Reeh, N., and Huybrechts, P.: The Greenland ice sheet through the last glacial-interglacial cycle, Palaeogeography, Palaeoclimatology, Palaeoecology, 90, 385–394, https://doi.org/10.1016/S0031-0182(12)80037-X, 1991. a
Leysinger Vieli, G. J., Martín, C., Hindmarsh, R. C., and Lüthi, M. P.: Basal freeze-on generates complex ice-sheet stratigraphy, Nat. Commun., 9, 1–13, https://doi.org/10.1038/s41467-018-07083-3, 2018. a
Lorius, C., Jouzel, J., Ritz, C., Merlivat, L., Barkov, N. I., Korotkevich, Y. S., and Kotlyakov, V. M.: A 150,000-year climatic record from Antarctic ice, Nature, 316, 591–596, https://doi.org/10.1038/316591a0, 1985. a
MacGregor, J. A., Fahnestock, M. A., Catania, G. A., Paden, J. D., Prasad Gogineni, S., Young, S. K., Rybarski, S. C., Mabrey, A. N., Wagman, B. M., and Morlighem, M.: Radiostratigraphy and age structure of the Greenland Ice Sheet, J. Geophys. Res.-Earth, 120, 212–241, https://doi.org/10.1002/2014JF003215, 2015. a
MacGregor, J. A., Fahnestock, M. A., Catania, G. A., Aschwanden, A., Clow, G. D., Colgan, W. T., Gogineni, S. P., Morlighem, M., Nowicki, S. M., Paden, J. D., Price, S. F., and Seroussi, H.: A synthesis of the basal thermal state of the Greenland Ice Sheet, J. Geophys. Res.-Earth, 121, 1328–1350, https://doi.org/10.1002/2015JF003803, 2016. a, b, c
Marcott, S. A., Bauska, T. K., Buizert, C., Steig, E. J., Rosen, J. L., Cuffey, K. M., Fudge, T. J., Severinghaus, J. P., Ahn, J., Kalk, M. L., McConnell, J. R., Sowers, T., Taylor, K. C., White, J. W., and Brook, E. J.: Centennial-scale changes in the global carbon cycle during the last deglaciation, Nature, 514, 616–619, https://doi.org/10.1038/nature13799, 2014. a
Marshall, S. J. and Cuffey, K. M.: Peregrinations of the Greenland Ice Sheet divide in the last glacial cycle: Implications for central Greenland ice cores, Earth Planet. Sc. Lett., 179, 73–90, https://doi.org/10.1016/S0012-821X(00)00108-4, 2000. a
Meese, D. A., Gow, A. J., Alley, R. B., Zielinski, G. A., Grootes, P. M., Ram, M., Taylor, K. C., Mayewski, P. A., and Bolzan, J. F.: The Greenland Ice Sheet Project 2 depth-age scale: Methods and results, J. Geophys. Res.-Oceans, 102, 26411–26423, https://doi.org/10.1029/97JC00269, 1997. a
Metropolis, N., Rosenbluth, A. W., Rosenbluth, M. N., Teller, A. H., and Teller, E.: Equation of state calculations by fast computing machines, J. Chem. Phys., 21, 1087–1092, https://doi.org/10.1063/1.1699114, 1953. a, b
Millar, D.: Acidity levels in ice sheets from radio echo-sounding, Ann. Glaciol., 3, 199–203, https://doi.org/10.3189/S0260305500002779, 1982. a
Mojtabavi, S., Wilhelms, F., Cook, E., Davies, S. M., Sinnl, G., Skov Jensen, M., Dahl-Jensen, D., Svensson, A., Vinther, B. M., Kipfstuhl, S., Jones, G., Karlsson, N. B., Faria, S. H., Gkinis, V., Kjær, H. A., Erhardt, T., Berben, S. M. P., Nisancioglu, K. H., Koldtoft, I., and Rasmussen, S. O.: A first chronology for the East Greenland Ice-core Project (EGRIP) over the Holocene and last glacial termination, Clim. Past, 16, 2359–2380, https://doi.org/10.5194/cp-16-2359-2020, 2020. a, b, c, d, e, f, g
Morlighem, M., Williams, C. N., Rignot, E., An, L., Arndt, J. E., Bamber, J. L., Catania, G., Chauché, N., Dowdeswell, J. A., Dorschel, B., Fenty, I., Hogan, K., Howat, I., Hubbard, A., Jakobsson, M., Jordan, T. M., Kjeldsen, K. K., Millan, R., Mayer, L., Mouginot, J., Noël, B. P., O'Cofaigh, C., Palmer, S., Rysgaard, S., Seroussi, H., Siegert, M. J., Slabon, P., Straneo, F., van den Broeke, M. R., Weinrebe, W., Wood, M., and Zinglersen, K. B.: BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation, Geophys. Res. Lett., 44, 11,051–11,061, https://doi.org/10.1002/2017GL074954, 2017. a
Mosegaard, K.: Resolution analysis of general inverse problems through inverse Monte Carlo sampling, Inverse Probl., 14, 405, 1998. a
Mosegaard, K. and Tarantola, A.: Monte Carlo sampling of solutions to inverse problems, J. Geophys. Res., 100, 12431 –12447, https://doi.org/10.1029/94jb03097, 1995. a
Mottram, R., Simonsen, S. B., Svendsen, S. H., Barletta, V. R., Sørensen, L. S., Nagler, T., Wuite, J., Groh, A., Horwath, M., Rosier, J., Solgaard, A., Hvidberg, C. S., and Forsberg, R.: An integrated view of greenland ice sheet mass changes based on models and satellite observations, Remote Sens.-Basel, 11, 1–26, https://doi.org/10.3390/rs11121407, 2019. a
NEEM Community members, Dahl-Jensen, D., Albert, M., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Chuchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davis, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L., Gfeller, G., Gkinis, V., Gogineni, S., Goto-Azuma, K., Grinsted, A., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C., Iizuka, Y., Jenk, T., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, S., Kjær, H. A., Koutnik, M., Kuramoto, T., Köhler, P., Laepple, T., Landais, A., Langen, P., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lippenkov, V., Mirtinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnel, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A. J., Paden, J., Panton, C., Pattyn, F., Petit, J. R., Pol, K., Popp, T., Possnert, G., Prié, F., Prokopiou, M., Quique, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Roeckeman, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A., Schwander, J., Schüpbach, S., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, D., Stocker, T., Stowasser, C., Sturevik, A. S., Sturges, B., Sveinbjörnsdottir, A., Svensson, A., Tison, J.-L., Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, M., Witrant, E., Wolff, E., Xiao, C., and Zheng, J.: Eemian interglacial reconstructed from a Greenland folded ice core, Nature, 493, 489–494, https://doi.org/10.1038/nature11789, 2013. a
Paren, J. G. and Robin, G. D. Q.: Internal Reflections in Polar Ice Sheets, J. Glaciol., 14, 251–259, https://doi.org/10.3189/s0022143000021730, 1975. a
Parrenin, F., Barnola, J.-M., Beer, J., Blunier, T., Castellano, E., Chappellaz, J., Dreyfus, G., Fischer, H., Fujita, S., Jouzel, J., Kawamura, K., Lemieux-Dudon, B., Loulergue, L., Masson-Delmotte, V., Narcisi, B., Petit, J.-R., Raisbeck, G., Raynaud, D., Ruth, U., Schwander, J., Severi, M., Spahni, R., Steffensen, J. P., Svensson, A., Udisti, R., Waelbroeck, C., and Wolff, E.: The EDC3 chronology for the EPICA Dome C ice core, Clim. Past, 3, 485–497, https://doi.org/10.5194/cp-3-485-2007, 2007. a
Petit, J. R., Raynaud, D., Basile, I., Chappellaz, J., Davisk, M., Ritz, C., Delmotte, M., Legrand, M., Lorius, C., Pe, L., and Saltzmank, E.: Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica, Nature, 399, 429–436, https://doi.org/10.1038/20859, 1999. a, b
Porter, C., Morin, P., Howat, I., Noh, M.-J., 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, Michael, J., 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, https://doi.org/10.7910/DVN/OHHUKH, 2018. a
Raisbeck, G. M., Yiou, F., Jouzel, J., and Stocker, T. F.: Direct north-south synchronization of abrupt climate change record in ice cores using Beryllium 10, Clim. Past, 3, 541–547, https://doi.org/10.5194/cp-3-541-2007, 2007. a
Rasmussen, S., Seierstad, I., Andersen, K. K., Bigler, M., Dahl-Jensen, D., and Johnsen, S.: Synchronization of the NGRIP, GRIP, and GISP2 ice cores across MIS 2 and palaeoclimatic implications, Quaternary Sci. Rev., 27, 18–28, https://doi.org/10.1016/j.quascirev.2007.01.016, 2008. a, b
Rasmussen, S. O., Andersen, K. K., Svensson, A. M., Steffensen, J. P., Vinther, B. M., Clausen, H. B., Siggaard-Andersen, M. L., Johnsen, S. J., Larsen, L. B., Dahl-Jensen, D., Bigler, M., Röthlisberger, R., Fischer, H., Goto-Azuma, K., Hansson, M. E., and Ruth, U.: A new Greenland ice core chronology for the last glacial termination, J. Geophys. Res.-Atmos., 111, 1–16, https://doi.org/10.1029/2005JD006079, 2006. a, b
Rasmussen, S. O., Abbott, P. M., Blunier, T., Bourne, A. J., Brook, E., Buchardt, S. L., Buizert, C., Chappellaz, J., Clausen, H. B., Cook, E., Dahl-Jensen, D., Davies, S. M., Guillevic, M., Kipfstuhl, S., Laepple, T., Seierstad, I. K., Severinghaus, J. P., Steffensen, J. P., Stowasser, C., Svensson, A., Vallelonga, P., Vinther, B. M., Wilhelms, F., and Winstrup, M.: A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core, Clim. Past, 9, 2713–2730, https://doi.org/10.5194/cp-9-2713-2013, 2013. a, b, c
Rasmussen, S. O., Bigler, M., Blockley, S. P., Blunier, T., Buchardt, S. L., Clausen, H. B., Cvijanovic, I., Dahl-Jensen, D., Johnsen, S. J., Fischer, H., Gkinis, V., Guillevic, M., Hoek, W. Z., Lowe, J. J., Pedro, J. B., Popp, T., Seierstad, I. K., Steffensen, J. P., Svensson, A. M., Vallelonga, P., Vinther, B. M., Walker, M. J. C., Wheatley, J. J., and Winstrup, M.: A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy, Quaternary Sci. Rev., 106, 14–28, https://doi.org/10.1016/j.quascirev.2014.09.007, 2014. a
Raynaud, D., Chappellaz, J., Ritz, C., and Martinerie, P.: Air content along the Greenland Ice Core Project core: A record of surface climatic parameters and elevation in central Greenland, J. Geophys. Res.-Oceans, 102, 26607–26613, https://doi.org/10.1029/97JC01908, 1997. a
Rignot, E. and Mouginot, J.: Ice flow in Greenland for the international polar year 2008–2009, Geophys. Res. Lett., 39, 1–7, https://doi.org/10.1029/2012GL051634, 2012. a
Riverman, K. L., Alley, R. B., Anandakrishnan, S., Christianson, K., Holschuh, N. D., Medley, B., Muto, A., and Peters, L. E.: Enhanced Firn Densification in High-Accumulation Shear Margins of the NE Greenland Ice Stream, J. Geophys. Res.-Earth, 124, 365–382, https://doi.org/10.1029/2017JF004604, 2019. a
Robin, G. d. Q. and Millar, D. H. M.: Flow Of Ice Sheets In The Vicinity Of Subglacial Peaks, Ann. Glaciol., 3, 290–294, https://doi.org/10.3189/s0260305500002949, 1982. a
Robin, G. d. Q., Evans, S., and Bailey, J. T.: Interpretation of radio echo sounding in polar ice sheets, Philos. T. R. Soc. S.-A, 265, 437–505, https://doi.org/10.1098/rsta.1969.0063, 1969. a
Salamatin, A. N., Lipenkov, V. Y., Barkov, N. I., Jouzel, J., Petit, J. R., and Raynaud, D.: Ice core age dating and paleothermometer calibration based on isotope and temperature profiles from deep boreholes at Vostok Station (East Antarctica), J. Geophys. Res.-Atmos., 103, 8963–8977, https://doi.org/10.1029/97JD02253, 1998. a
Seierstad, I. K., Abbott, P. M., Bigler, M., Blunier, T., Bourne, A. J., Brook, E., Buchardt, S. L., Buizert, C., Clausen, H. B., Cook, E., Dahl-Jensen, D., Davies, S. M., Guillevic, M., Johnsen, S. J., Pedersen, D. S., Popp, T. J., Rasmussen, S. O., Severinghaus, J. P., Svensson, A., and Vinther, B. M.: Consistently dated records from the Greenland GRIP, GISP2 and NGRIP ice cores for the past 104ka reveal regional millennial-scale δ18O gradients with possible Heinrich event imprint, Quaternary Sci. Rev., 106, 29–46, https://doi.org/10.1016/j.quascirev.2014.10.032, 2014. a, b
Simonsen, S. B. and Sørensen, L. S.: Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry, Remote Sens. Environ., 190, 207–216, https://doi.org/10.1016/j.rse.2016.12.012, 2017. a, b
Smith-Johnsen, S., de Fleurian, B., Schlegel, N., Seroussi, H., and Nisancioglu, K.: Exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream, The Cryosphere, 14, 841–854, https://doi.org/10.5194/tc-14-841-2020, 2020a. a
Smith-Johnsen, S., Schlegel, N. J., de Fleurian, B., and Nisancioglu, K. H.: Sensitivity of the Northeast Greenland Ice Stream to Geothermal Heat, J. Geophys. Res.-Earth, 125, 1–14, https://doi.org/10.1029/2019JF005252, 2020b. a
Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Rasmussen, S. O., Röthlisberger, R., Steffensen, J. P., and Vinther, B. M.: The Greenland ice core chronology 2005, 15–42 ka. Part 2: comparison to other records, Quaternary Sci. Rev., 25, 3258–3267, https://doi.org/10.1029/2005JD006079, 2006. a
Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin, F., Rasmussen, S. O., Röthlisberger, R., Seierstad, I., Steffensen, J. P., and Vinther, B. M.: A 60 000 year Greenland stratigraphic ice core chronology, Clim. Past, 4, 47–57, https://doi.org/10.5194/cp-4-47-2008, 2008. a
Vallelonga, P., Christianson, K., Alley, R. B., Anandakrishnan, S., Christian, J. E. M., Dahl-Jensen, D., Gkinis, V., Holme, C., Jacobel, R. W., Karlsson, N. B., Keisling, B. A., Kipfstuhl, S., Kjær, H. A., Kristensen, M. E. L., Muto, A., Peters, L. E., Popp, T., Riverman, K. L., Svensson, A. M., Tibuleac, C., Vinther, B. M., Weng, Y., and Winstrup, M.: Initial results from geophysical surveys and shallow coring of the Northeast Greenland Ice Stream (NEGIS), The Cryosphere, 8, 1275–1287, https://doi.org/10.5194/tc-8-1275-2014, 2014. a, b
Vinther, B., Buchardt, S., Clausen, H., Dahl-Jensen, D., Johnsen, S., Fisher, D., Koerner, R., Raynaud, D., Lipenkov, V., Andersen, K. K., Blunier, T., Rasmussen, S. O., Steffensen, J. P., and Svensson, A. M.: Holocene thinning of the Greenland ice sheet, Nature, 461, 385–388, https://doi.org/10.1038/nature08355, 2009.
a
Vinther, B. M., Clausen, H. B., Johnsen, S. J., Rasmussen, S. O., Andersen, K. K., Buchardt, S. L., Dahl-Jensen, D., Seierstad, I. K., Siggaard-Andersen, M.-L., Steffensen, J. P., Svensson, A., Olsen, J., and Heinemeier, J.: A synchronized dating of three Greenland ice cores throughout the Holocene, J. Geophys. Res.-Atmos., 111, D13102, https://doi.org/10.1029/2005JD006921, 2006. a
Waddington, E. D., Neumann, T. A., Koutnik, M. R., Marshall, H. P., and Morse, D. L.: Inference of accumulation-rate patterns from deep layers in glaciers and ice sheets, J. Glaciol., 53, 694–712, https://doi.org/10.3189/002214307784409351, 2007. a, b, c
Walker, M., Johnes, S., Rasmussen, S. O., Popp, T., Steffensen, J.-P.,
Gibbard, P., Hoek, W., Lowe, J., Andrews, J., Björck, S., Cwynar, L. C.,
Hughen, K., Kershaw, P., Kromer, B., Litt, T., Lowe, D. J., Nakagawa, T.,
Newnham, R., and Schwander, J.: Formal definition and dating of the GSSP
(Global Stratotype Section and Point) for the base of the Holocene using the
Greenland NGRIP ice core, and selected auxiliary records, J. Quaternary Sci.,
24, 3–17, https://doi.org/10.1002/jqs.1227, 2009. a
Weertman, J.: Sliding–no sliding zone effect and age determination of ice cores, Quaternary Res., 6, 203–207, https://doi.org/10.1016/0033-5894(76)90050-8, 1976. a, b, c
Whillans, I. M.: Radio-echo layers and the recent stability of the West Antarctic ice sheet, Nature, 264, 152–155, https://doi.org/10.1038/264152a0, 1976. a, b
Whillans, I. M. and Johnsen, S. J.: Longitudinal variations in glacial flow: theory and test using data from the Byrd Station strain network, Antarctica, J. Glaciol., 29, 78–97, https://doi.org/10.1017/S0022143000005165, 1983. a, b
Wolovick, M. J., Creyts, T. T., Buck, W. R., and Bell, R. E.: Traveling slippery patches produce thickness-scale folds in ice sheets, Geophys. Res. Lett., 41, 8895–8901, https://doi.org/10.1002/2014GL062248, 2014. a
Yiou, F., Raisbeck, G. M., Baumgartner, S., Beer, J., Hammer, C., Johnsen, S., Jouzel, J., Kubik, P. W., Lestringuez, J., Stiévenard, M., Suter, M., and Yiou, P.: Beryllium 10 in the Greenland Ice Core Project ice core at Summit, Greenland, J. Geophys. Res.-Oceans, 102, 26783–26794, https://doi.org/10.1029/97JC01265, 1997. a
Zeising, O. and Humbert, A.: Indication of high basal melting at the EastGRIP drill site on the Northeast Greenland Ice Stream, The Cryosphere, 15, 3119–3128, https://doi.org/10.5194/tc-15-3119-2021, 2021. a, b, c
Short summary
We simulate the ice flow in the onset region of the Northeast Greenland Ice Stream to determine the source area and past accumulation rates of ice found in the EastGRIP ice core. This information is required to correct for bias in ice-core records introduced by the upstream flow effects. Our results reveal that the increasing accumulation rate with increasing upstream distance is predominantly responsible for the constant annual layer thicknesses observed in the upper 900 m of the ice core.
We simulate the ice flow in the onset region of the Northeast Greenland Ice Stream to determine...
