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2. Bias in modeled Greenland ice sheet melt revealed by ASCAT

Author

Puggaard, Anna, primary, Hansen, Nicolaj, additional, Mottram, Ruth, additional, Nagler, Thomas, additional, Scheiblauer, Stefan, additional, Simonsen, Sebastian B., additional, Sørensen, Louise S., additional, Wuite, Jan, additional, and Solgaard, Anne M., additional

Published
2024
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4. Arctic Freshwater Fluxes from Earth Observation Data

Author

Andersen, Ole B., Nilsen, Karina, Sørensen, Louise S., Skourup, Henriette, Andersen, Natalia H., Nagler, Thomas, Wuite, Jan, Kouraev, Alexei, Zakharova, Elena, Fernandez, Diego, Freymueller, Jeffrey T., Series Editor, Sánchez, Laura, Assistant Editor, Mertikas, Stelios P., editor, and Pail, Roland, editor

Published
2020
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8. Drivers of Seasonal Land‐Ice‐Flow Variability in the Antarctic Peninsula.

Author

Boxall, Karla, Christie, Frazer D. W., Willis, Ian C., Wuite, Jan, Nagler, Thomas, and Scheiblauer, Stefan

Subjects
ICE shelves, EL Nino, SEASONS, SOUTHERN oscillation, OCEAN temperature, ANTARCTIC oscillation
Abstract

Land‐ice flow in Antarctica has experienced multi‐annual acceleration in response to increased rates of ice thinning, ice‐shelf collapse and grounding‐line retreat. Superimposed upon this trend, recent observations have revealed that land‐ice flow in the Antarctic Peninsula exhibits seasonal velocity variability with distinct summertime speed‐ups. The mechanism, or mechanisms, responsible for driving this seasonality are unconstrained at present, yet detailed, process‐based understanding of such forcing will be important for accurately estimating Antarctica's future contributions to sea level. Here, we perform time‐series analysis on an array of remotely sensed, modeled and reanalysis data sets to examine the influence of potential drivers of ice‐flow seasonality in the Antarctic Peninsula. We show that both meltwater presence and ocean temperature act as statistically significant precursors to summertime ice‐flow acceleration, although each elicits an ice‐velocity response after a distinct lag, with the former prompting a more immediate response. Furthermore, we find that the timing and magnitude of these local drivers are influenced by large‐scale climate phenomena, namely the Amundsen Sea Low and the El Niño Southern Oscillation, with the latter initiating an anomalous wintertime ice‐flow acceleration event in 2016. This hitherto unidentified link between seasonal ice flow and large‐scale climatic forcing may have important implications for ice discharge at and beyond the Antarctic Peninsula in the future, depending upon how the magnitude, frequency and duration of such climate phenomena evolve in a warming world. Plain Language Summary: Over the past three decades, the speed of Antarctica's seaward‐flowing glaciers has accelerated, resulting in increased ice mass‐loss to the ocean and corresponding global sea‐level rise. Recent work has found that glaciers in the Antarctic Peninsula also experience changes in their flow speed throughout the year, with faster flow (of up to 15% relative to annual‐averaged rates) occurring during the summertime. The physical processes responsible for controlling this seasonal behavior, however, are unknown. Here, we examine a range of satellite, atmosphere, and ocean records to determine the main environmental drivers of this seasonal response. Our results show that both surface and oceanic processes are important in driving this behavior, but that the influence of surface processes is more immediate than the relatively time‐delayed, or "lagged," effects of the ocean. We also find that both surface and oceanic processes are themselves subject to the influence of larger‐scale climate phenomena, including the El Niño Southern Oscillation. Overall, our results provide new insights into the environmental controls on the recently observed seasonal pattern of ice flow in Antarctica. Key Points: Surface meltwater extent and sea‐ice‐modulated oceanic forcing act as statistically significant precursors to summertime ice‐flow acceleration in the Antarctic PeninsulaSurface meltwater presence and enhanced ocean temperatures presage summertime acceleration with different temporal lead timesA relationship exists between El Niño Southern Oscillation and Antarctic ice‐flow seasonality, with the unprecedented magnitude El Niño event of 2016 driving an anomalous wintertime speed‐up through enhanced local surface and oceanic forcing [ABSTRACT FROM AUTHOR]

Published
2024
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12. Annual mass budget of Antarctic ice shelves, 1997-2021 (WP3 EO Workshop)

Author

Davison, Benjamin, Hogg, Anna, Gourmelen, Noel, Jakob, Livia, Wuite, Jan, Nagler, Thomas, Greene, Chad, Andreasen, Julia, and Engdahl, Marcus

Abstract

This presentation was held at the OCEAN:ICE This presentation was held at the OCEAN:ICE WP3 EO Workshop exploring Antarctic fluxes in observations and climate and ice sheet models. The workshop took place in Copenhagen, Denmark from the 23rd to 24th of May in 2023. Benjamin Davison delivered thispresentation on May 23rd, 2023 during Session 1 of the workshop, Antarctic surface datasets from in-situ and Earth Observations. &nbsp

Published
2023
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13. Arctic Freshwater Fluxes from Earth Observation Data

Author

Andersen, Ole B., primary, Nilsen, Karina, additional, Sørensen, Louise S., additional, Skourup, Henriette, additional, Andersen, Natalia H., additional, Nagler, Thomas, additional, Wuite, Jan, additional, Kouraev, Alexei, additional, Zakharova, Elena, additional, and Fernandez, Diego, additional

Published
2019
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14. Sub-Monthly Mass Change Signal over the llulissat Glacier in Greenland from GRACE-FO Laser Interferometry Data

Author

Jenny, B., Forsberg, René, Jensen, T., Wuite, Jan, Nagler, T., Han, S.-C., Jenny, B., Forsberg, René, Jensen, T., Wuite, Jan, Nagler, T., and Han, S.-C.

Abstract

GRACE(-FO) monthly products are produced routinely using measurements of the orbital motion and the K-Band measurements of the distance between the two satellites. From these solutions, we gained great insight into the water cycle, ice mass balance, and ocean currents for the past twenty years. But what can we do, if we want to study sub­monthly processes? Ghobadi-Far et al. (2022) showed the possibility to use the intersatellite laser ranging measurements on GRACE Follow­On for the analysis of the gravity signal along the orbit. So far, this method has been used to e.g. study the mass change in the Amazon or to study storm surges over the northern sea (Weigelt et. al. 2023). In this study, we focus on the Greenland Ice Sheet and especially the region around Jakobshavn/llulissat glacier.

Published
2023

15. Ocean warming drives rapid dynamic activation of a marine-terminating glacier on the west Antarctic Peninsula

Author

Wallis, Benjamin J., Hogg, Anne E., Meredith, Michael P., Close, Romilly, Hardy, Dominic, McMillan, Malcolm, Wuite, Jan, Nagler, Thomas, Moffat, Carlos, Wallis, Benjamin J., Hogg, Anne E., Meredith, Michael P., Close, Romilly, Hardy, Dominic, McMillan, Malcolm, Wuite, Jan, Nagler, Thomas, and Moffat, Carlos

Abstract

Ice dynamic change is the primary cause of mass loss from the Antarctic Ice Sheet, thus it is important to understand the processes driving ice-ocean interactions and the timescale on which major change can occur. Here we use satellite observations to measure a rapid increase in speed and collapse of the ice shelf fronting Cadman Glacier in the absence of surface meltwater ponding. Between November 2018 and December 2019 ice speed increased by 94 ± 4% (1.47 ± 0.6 km/yr), ice discharge increased by 0.52 ± 0.21 Gt/yr, and the calving front retreated by 8 km with dynamic thinning on grounded ice of 20.1 ± 2.6 m/yr. This change was concurrent with a positive temperature anomaly in the upper ocean, where a 400 m deep channel allowed warm water to reach Cadman Glacier driving the dynamic activation, while neighbouring Funk and Lever Glaciers were protected by bathymetric sills across their fjords. Our results show that forcing by warm ocean water can cause the rapid onset of dynamic imbalance and increased ice discharge from glaciers on the Antarctic Peninsula, highlighting the region’s sensitivity to future climate variability.

Published
2023

17. Ice shelf area and ice shelf area change from Sentinel-1 SAR and Cryosat-2 altimetry data

Author

Floricioiu, Dana, Krieger, Lukas, Wuite, Jan, and Nagler, Thomas

Abstract

Floating ice shelves fringe 74% of Antarctica's coastline, providing a direct link between the ice sheet and the surrounding oceans. A better understanding of Antarctic ice shelves and the physical processes affecting them has been the main objective of ESA’s Polar+ Ice Shelves project. A suite of geophysical products based on Earth Observation datasets from the last decade and modelling has been defined and produced over selected target ice shelves in Antarctica. One of these products, the ice shelf area change, is an important indicator of ice shelf stability in a warming climate, being affected by grounding line retreat as a possible consequence of ice thinning and calving events including ice shelf disintegration or collapse.An ice shelf is bounded at its seaward margin by the calving front while its inland border to the grounded ice of the Antarctic continent is given by the grounding line. Our calving front location is derived from Cryosat-2 swath elevation, while the grounding line is detected as the upper limit of ice shelf tidal flexure from Sentinel-1 and, prior to 2015, ERS-1/2 interferometric data. Time series of complete ice shelf delineations are obtained from the combination of these two products. It is possible to track absolute and relative area change of an ice shelf and additionally to partition the change into the individual contributions induced by the calving front and grounding-line migration. Examples of annual ice shelf perimeters of major ice shelves from 2011 to the present will be shown., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

21. Three different glacier surges at a spot: what satellites observe and what not

Author

Paul, Frank, Piermattei, Livia; https://orcid.org/0000-0003-2814-8659, Treichler, Désirée, Gilbert, Lin, Girod, Luc; https://orcid.org/0000-0003-3627-5885, Kääb, Andreas; https://orcid.org/0000-0002-6017-6564, Libert, Ludivine, Nagler, Thomas; https://orcid.org/0000-0003-1298-8469, Strozzi, Tazio; https://orcid.org/0000-0002-9054-951X, Wuite, Jan; https://orcid.org/0000-0001-9333-1586, Paul, Frank, Piermattei, Livia; https://orcid.org/0000-0003-2814-8659, Treichler, Désirée, Gilbert, Lin, Girod, Luc; https://orcid.org/0000-0003-3627-5885, Kääb, Andreas; https://orcid.org/0000-0002-6017-6564, Libert, Ludivine, Nagler, Thomas; https://orcid.org/0000-0003-1298-8469, Strozzi, Tazio; https://orcid.org/0000-0002-9054-951X, and Wuite, Jan; https://orcid.org/0000-0001-9333-1586

Abstract

In the Karakoram, dozens of glacier surges occurred in the past 2 decades, making the region a global hotspot. Detailed analyses of dense time series from optical and radar satellite images revealed a wide range of surge behaviour in this region: from slow advances longer than a decade at low flow velocities to short, pulse-like advances over 1 or 2 years with high velocities. In this study, we present an analysis of three currently surging glaciers in the central Karakoram: North and South Chongtar Glaciers and an unnamed glacier referred to as NN9. All three glaciers flow towards the same small region but differ strongly in surge behaviour. A full suite of satellites (e.g. Landsat, Sentinel-1 and 2, Planet, TerraSAR-X, ICESat-2) and digital elevation models (DEMs) from different sources (e.g. Shuttle Radar Topography Mission, SRTM; Satellite Pour l’Observation de la Terre, SPOT; High Mountain Asia DEM, HMA DEM) are used to (a) obtain comprehensive information about the evolution of the surges from 2000 to 2021 and (b) to compare and evaluate capabilities and limitations of the different satellite sensors for monitoring surges of relatively small glaciers in steep terrain. A strongly contrasting evolution of advance rates and flow velocities is found, though the elevation change pattern is more similar. For example, South Chongtar Glacier had short-lived advance rates above 10 km yr−1, velocities up to 30 m d−1, and surface elevations increasing by 170 m. In contrast, the neighbouring and 3-times-smaller North Chongtar Glacier had a slow and near-linear increase in advance rates (up to 500 m yr−1), flow velocities below 1 m d−1 and elevation increases up to 100 m. The even smaller glacier NN9 changed from a slow advance to a full surge within a year, reaching advance rates higher than 1 km yr−1. It seems that, despite a similar climatic setting, different surge mechanisms are at play, and a transition from one mechanism to another can occur during a single surge. T

Published
2022

24. The jökulhlaup from the subglacial lake Grímsvötn, beneath Vatnajökull ice cap, in November-December 2021, revealing new insight in to slowly rising jökulhlaups

Author

Magnússon, Eyjólfur, primary, Drouin, Vincent, additional, Pálsson, Finnur, additional, Hannesdóttir, Krista, additional, Belart, Joaquín M. C., additional, Sigurðsson, Gunnar, additional, Wuite, Jan, additional, Jóhanneson, Tómas, additional, Ófeigsson, Benedikt G., additional, Nagler, Thomas, additional, Gudmundsson, Magnús T., additional, Högnadóttir, Thórdís, additional, Parks, Michelle, additional, Roberts, Matthew J., additional, and Berthier, Etienne, additional

Published
2022
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26. 4D Antarctica

Author

Gourmelen, Noel, Malczyk, George, Wearing, Martin, Goldberg, Daniel, Ewart, Martin, Leduc-Leballeur, Marion, Macelloni, Giovanni, Wessel, Birgit, Werder, Mauro, Wuite, Jan, Nagler, Thomas, Shepherd, Andrew, Barletta, Valentina, Forsberg, Rene, Corr, Diamuid, Leeson, Amber, McMillian, Malcom, Rigby, Richard, Hogg, Anna E., Ritz, Catherine, and Picard, Ghislain

Subjects
subglacial, supra-glacial, Earth Observation missions, hydrology, ice-sheet, Anarctica
Published
2022

31. The 4DGreenland project: Greenland hydrology assessment from remote sensing

Author

Sandberg Sørensen, Louise, B. Simonsen, Sebastian, Wintrup, Mai, Andersen, Natalia, Arildsen, Rasmus, Wuite, Jan, Nagler, Thomas, Hetzenecker, Markus, Shepherd, Andrew, Lemmetyinen, Juha, Kontu, Anna, Rautiainen, Kimmo, Roth, Achim, Wessel, Birgit, Leeson, Amber, McMillian, Malcom, Melling, Laura, Corr, Diarmuid, Glen, Emily, Zang, Ce, Fantin, Daniele, Vermeer, Martijn, gourmelen, Noel, Horton, Alex, Karlsson, Nanna, Solgaard, Anne, and Ribeiro, Sofia

Subjects
remote sensing, Hydrology (agriculture), Remote sensing (archaeology), assessment, Greenland, Environmental science, hydrology, Remote sensing
Abstract

The high latitudes of the Northern Hemisphere have experienced the largest regional warming over the last decades. On the Greenland ice sheet, rapid changes are observed in response to temperature increase, with the amount of liquid water at the surface particularly increasing. Understanding Greenland’s ice sheet hydrology is essential to assess its contribution to global sea-level rise in a future warming climate.With the objective of maximizing the use of Earth Observation (EO) data, the European Space Agency (ESA) has funded the 2-year project 4DGreenland (https://4dgreenland.eo4cryo.dk/) to assess and quantify the hydrology of the Greenland ice sheet. The project is focused on dynamic variations in the hydrological components of the ice sheet, and on quantifying the water fluxes between reservoirs including surface melt, supraglacial lakes and rivers, and subglacial melt and lakes. Efforts will focus on a thorough analysis of various components of the hydrological network in selected test regions and their impact on ice sheet flow. 4DGreenland started in September 2020. Here, we will present the project objectives, methods, and show initial results obtained within the project such as a comparison of supraglacial lake depths from optical imagery and ICESat-2 altimetry data, estimation of basal melt water production, and identification and mapping of surface meltwater presence and subglacial lakes from EO data.

Published
2021

33. Mass balance of the Greenland Ice Sheet from 1992 to 2018

Author

Shepherd, Andrew, Ivins, Erik, Rignot, Eric, Smith, Ben, van den Broeke, Michiel, Velicogna, Isabella, Whitehouse, Pippa, Briggs, Kate, Joughin, Ian, Krinner, Gerhard, Nowicki, Sophie, Payne, Tony, Scambos, Ted, Schlegel, Nicole, Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas, Babonis, Greg, Barletta, Valentina R., Bjørk, Anders A., Blazquez, Alejandro, Bonin, Jennifer, Colgan, William, Csatho, Beata, Cullather, Richard, Engdahl, Marcus E., Felikson, Denis, Fettweis, Xavier, Forsberg, Rene, Hogg, Anna E., Gallee, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian, Hanna, Edward, Harig, Christopher, Helm, Veit, Horvath, Alexander, Horwath, Martin, Khan, Shfaqat, Kjeldsen, Kristian K., Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit, Loomis, Bryant, Luthcke, Scott, McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian, Mohajerani, Yara, Moore, Philip, Mottram, Ruth, Mouginot, Jeremie, Moyano, Gorka, Muir, Alan, Nagler, Thomas, Nield, Grace, Nilsson, Johan, Noël, Brice, Otosaka, Ines, Pattle, Mark E., Peltier, W. Richard, Pie, Nadège, Rietbroek, Roelof, Rott, Helmut, Sørensen, Louise Sandberg, Sasgen, Ingo, Save, Himanshu, Scheuchl, Bernd, Schrama, Ernst, Schröder, Ludwig, Seo, Ki-Weon, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler, Talpe, Matthieu, Tarasov, Lev, Jan van de Berg, Willem, van der Wal, Wouter, van Wessem, Melchior, Vishwakarma, Bramha Dutt, Wiese, David, Wilton, David, Wagner, Thomas, Wouters, Bert, Wuite, Jan, Team, The IMBIE, Marine and Atmospheric Research, Sub Dynamics Meteorology, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Andrew Shepherd, Erik Ivin, Eric Rignot, Ben Smith, Michiel van den Broeke, Isabella Velicogna, Pippa Whitehouse, Kate Brigg, Ian Joughin, Gerhard Krinner, Sophie Nowicki, Tony Payne, Ted Scambo, Nicole Schlegel, A Geruo, Cécile Agosta, Andreas Ahlstrøm, Greg Baboni, Valentina R. Barletta, Anders A. Bjørk, Alejandro Blazquez, Jennifer Bonin, William Colgan, Beata Csatho, Richard Cullather, Marcus E. Engdahl, Denis Felikson, Xavier Fettwei, Rene Forsberg, Anna E. Hogg, Hubert Gallee, Alex Gardner, Lin Gilbert, Noel Gourmelen, Andreas Groh, Brian Gunter, Edward Hanna, Christopher Harig, Veit Helm, Alexander Horvath, Martin Horwath, Shfaqat Khan, Kristian K. Kjeldsen, Hannes Konrad, Peter L. Langen, Benoit Lecavalier, Bryant Loomi, Scott Luthcke, Malcolm McMillan, Daniele Melini, Sebastian Mernild, Yara Mohajerani, Philip Moore, Ruth Mottram, Jeremie Mouginot, Gorka Moyano, Alan Muir, Thomas Nagler, Grace Nield, Johan Nilsson, Brice Noël, Ines Otosaka, Mark E. Pattle, W. Richard Peltier, Nadège Pie, Roelof Rietbroek, Helmut Rott, Louise Sandberg Sørensen, Ingo Sasgen, Himanshu Save, Bernd Scheuchl, Ernst Schrama, Ludwig Schröder, Ki-Weon Seo, Sebastian B. Simonsen, Thomas Slater, Giorgio Spada, Tyler Sutterley, Matthieu Talpe, Lev Tarasov, Willem Jan van de Berg, Wouter van der Wal, Melchior van Wessem, Bramha Dutt Vishwakarma, David Wiese, David Wilton, Thomas Wagner, Bert Wouter, Jan Wuite, Marine and Atmospheric Research, and Sub Dynamics Meteorology

Subjects
geography, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Global warming, Greenland ice sheet, Climate change, Glacier, GLACIAL ISOSTATIC-ADJUSTMENT, RELATIVE SEA-LEVEL PETERMANN GLACIER, ELEVATION CHANGE, SURFACE, GRACE, CLIMATE, MODEL, ACCELERATION, ANTARCTICA, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Glacier mass balance, 13. Climate action, Taverne, [SDE]Environmental Sciences, SDG 13 - Climate Action, Environmental science, Climate model, Ice sheet, F840 Physical Geography, Meltwater, 0105 earth and related environmental sciences
Abstract

ArticlePublished: 10 December 2019This is an unedited manuscript that has been accepted for publication. Nature Research are providing this early version of the manuscript as a service to our customers. The manuscript will undergo copyediting, typesetting and a proof review before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers apply.Mass balance of the Greenland Ice Sheet from 1992 to 2018The IMBIE TeamNature (2019)Cite this article6914 Accesses1410 AltmetricMetricsdetailsAbstractIn recent decades, the Greenland Ice Sheet has been a major contributor to global sea-level rise1,2, and it is expected to be so in the future3. Although increases in glacier flow4–6 and surface melting7–9 have been driven by oceanic10–12 and atmospheric13,14 warming, the degree and trajectory of today’s imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet’s volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. Although the ice sheet was close to a state of balance in the 1990s, annual losses have risen since then, peaking at 335 ± 62 billion tonnes per year in 2011. In all, Greenland lost 3,800 ± 339 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.6 ± 0.9 millimetres. Using three regional climate models, we show that reduced surface mass balance has driven 1,971 ± 555 billion tonnes (52%) of the ice loss owing to increased meltwater runoff. The remaining 1,827 ± 538 billion tonnes (48%) of ice loss was due to increased glacier discharge, which rose from 41 ± 37 billion tonnes per year in the 1990s to 87 ± 25 billion tonnes per year since then. Between 2013 and 2017, the total rate of ice loss slowed to 217 ± 32 billion tonnes per year, on average, as atmospheric circulation favoured cooler conditions15 and as ocean temperatures fell at the terminus of Jakobshavn Isbræ16. Cumulative ice losses from Greenland as a whole have been close to the IPCC’s predicted rates for their high-end climate warming scenario17, which forecast an additional 50 to 120 millimetres of global sea-level rise by 2100 when compared to their central estimate.

Published
2020
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41. Mass balance of the Greenland Ice Sheet from 1992 to 2018

Author

Marine and Atmospheric Research, Sub Dynamics Meteorology, Shepherd, Andrew, Ivins, Erik, Rignot, Eric, Smith, Ben, van den Broeke, Michiel, Velicogna, Isabella, Whitehouse, Pippa, Briggs, Kate, Joughin, Ian, Krinner, Gerhard, Nowicki, Sophie, Payne, Tony, Scambos, Ted, Schlegel, Nicole, Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas, Babonis, Greg, Barletta, Valentina R., Bjørk, Anders A., Blazquez, Alejandro, Bonin, Jennifer, Colgan, William, Csatho, Beata, Cullather, Richard, Engdahl, Marcus E., Felikson, Denis, Fettweis, Xavier, Forsberg, Rene, Hogg, Anna E., Gallee, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian, Hanna, Edward, Harig, Christopher, Helm, Veit, Horvath, Alexander, Horwath, Martin, Khan, Shfaqat, Kjeldsen, Kristian K., Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit, Loomis, Bryant, Luthcke, Scott, McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian, Mohajerani, Yara, Moore, Philip, Mottram, Ruth, Mouginot, Jeremie, Moyano, Gorka, Muir, Alan, Nagler, Thomas, Nield, Grace, Nilsson, Johan, Noël, Brice, Otosaka, Ines, Pattle, Mark E., Peltier, W. Richard, Pie, Nadège, Rietbroek, Roelof, Rott, Helmut, Sørensen, Louise Sandberg, Sasgen, Ingo, Save, Himanshu, Scheuchl, Bernd, Schrama, Ernst, Schröder, Ludwig, Seo, Ki-Weon, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler, Talpe, Matthieu, Tarasov, Lev, Jan van de Berg, Willem, van der Wal, Wouter, van Wessem, Melchior, Vishwakarma, Bramha Dutt, Wiese, David, Wilton, David, Wagner, Thomas, Wouters, Bert, Wuite, Jan, Team, The IMBIE, Marine and Atmospheric Research, Sub Dynamics Meteorology, Shepherd, Andrew, Ivins, Erik, Rignot, Eric, Smith, Ben, van den Broeke, Michiel, Velicogna, Isabella, Whitehouse, Pippa, Briggs, Kate, Joughin, Ian, Krinner, Gerhard, Nowicki, Sophie, Payne, Tony, Scambos, Ted, Schlegel, Nicole, Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas, Babonis, Greg, Barletta, Valentina R., Bjørk, Anders A., Blazquez, Alejandro, Bonin, Jennifer, Colgan, William, Csatho, Beata, Cullather, Richard, Engdahl, Marcus E., Felikson, Denis, Fettweis, Xavier, Forsberg, Rene, Hogg, Anna E., Gallee, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian, Hanna, Edward, Harig, Christopher, Helm, Veit, Horvath, Alexander, Horwath, Martin, Khan, Shfaqat, Kjeldsen, Kristian K., Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit, Loomis, Bryant, Luthcke, Scott, McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian, Mohajerani, Yara, Moore, Philip, Mottram, Ruth, Mouginot, Jeremie, Moyano, Gorka, Muir, Alan, Nagler, Thomas, Nield, Grace, Nilsson, Johan, Noël, Brice, Otosaka, Ines, Pattle, Mark E., Peltier, W. Richard, Pie, Nadège, Rietbroek, Roelof, Rott, Helmut, Sørensen, Louise Sandberg, Sasgen, Ingo, Save, Himanshu, Scheuchl, Bernd, Schrama, Ernst, Schröder, Ludwig, Seo, Ki-Weon, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler, Talpe, Matthieu, Tarasov, Lev, Jan van de Berg, Willem, van der Wal, Wouter, van Wessem, Melchior, Vishwakarma, Bramha Dutt, Wiese, David, Wilton, David, Wagner, Thomas, Wouters, Bert, Wuite, Jan, and Team, The IMBIE

Published
2020

42. Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment

Author

Lhermitte, S.L.M. (author), Sun, Sainan (author), Shuman, Christopher (author), Wouters, B. (author), Pattyn, Frank (author), Wuite, Jan (author), Berthier, Etienne (author), Nagler, Thomas (author), Lhermitte, S.L.M. (author), Sun, Sainan (author), Shuman, Christopher (author), Wouters, B. (author), Pattyn, Frank (author), Wuite, Jan (author), Berthier, Etienne (author), and Nagler, Thomas (author)

Abstract

Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica with large consequences for global sea level. Yet, assessing how much and how fast both glaciers will weaken if these changes continue remains a major uncertainty as many of the processes that control their ice shelf weakening and grounding line retreat are not well understood. Here, we combine multisource satellite imagery with modeling to uncover the rapid development of damage areas in the shear zones of Pine Island and Thwaites ice shelves. These damage areas consist of highly crevassed areas and open fractures and are first signs that the shear zones of both ice shelves have structurally weakened over the past decade. Idealized model results reveal moreover that the damage initiates a feedback process where initial ice shelf weakening triggers the development of damage in their shear zones, which results in further speedup, shearing, and weakening, hence promoting additional damage development. This damage feedback potentially preconditions these ice shelves for disintegration and enhances grounding line retreat. The results of this study suggest that damage feedback processes are key to future ice shelf stability, grounding line retreat, and sea level contributions from Antarctica. Moreover, they underline the need for incorporating these feedback processes, which are currently not accounted for in most ice sheet models, to improve sea level rise projections., Mathematical Geodesy and Positioning, Physical and Space Geodesy

Published
2020
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43. Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment

Author

Sub Dynamics Meteorology, Marine and Atmospheric Research, Lhermitte, Stef, Sun, Sainan, Shuman, Christopher, Wouters, Bert, Pattyn, Frank, Wuite, Jan, Berthier, Etienne, Nagler, Thomas, Sub Dynamics Meteorology, Marine and Atmospheric Research, Lhermitte, Stef, Sun, Sainan, Shuman, Christopher, Wouters, Bert, Pattyn, Frank, Wuite, Jan, Berthier, Etienne, and Nagler, Thomas

Published
2020

45. Modelling the climate and surface mass balance of polar ice sheets using RACMO2 - Part 2

Author

van Wessem, J.M., Jan Van De Berg, Willem, Noël, Brice P.Y., van Meijgaard, Erik, Amory, Charles, Birnbaum, Gerit, Jakobs, Constantijn L., Krüger, Konstantin, Lenaerts, Jan T.M., Lhermitte, Stef, Ligtenberg, Stefan R.M., Medley, Brooke, Reijmer, Carleen H., Van Tricht, Kristof, Trusel, Luke D., van Ulft, Lambertus H., Wouters, Bert, Wuite, Jan, Van Den Broeke, Michiel R., Sub Dynamics Meteorology, Marine and Atmospheric Research, Sub Dynamics Meteorology, and Marine and Atmospheric Research

Subjects
lcsh:GE1-350, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, lcsh:QE1-996.5, Antarctic ice sheet, 010502 geochemistry & geophysics, Snow, Atmospheric sciences, 01 natural sciences, Ice shelf, Ice-sheet model, lcsh:Geology, Glacier mass balance, 13. Climate action, Climatology, Snowmelt, Environmental science, Climate model, Ice sheet, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Water Science and Technology, Earth-Surface Processes
Abstract

We evaluate modelled Antarctic ice sheet (AIS) near-surface climate, surface mass balance (SMB) and surface energy balance (SEB) from the updated polar version of the regional atmospheric climate model, RACMO2 (1979–2016). The updated model, referred to as RACMO2.3p2, incorporates upper-air relaxation, a revised topography, tuned parameters in the cloud scheme to generate more precipitation towards the AIS interior and modified snow properties reducing drifting snow sublimation and increasing surface snowmelt. Comparisons of RACMO2 model output with several independent observational data show that the existing biases in AIS temperature, radiative fluxes and SMB components are further reduced with respect to the previous model version. The model-integrated annual average SMB for the ice sheet including ice shelves (minus the Antarctic Peninsula, AP) now amounts to 2229 Gt y−1, with an interannual variability of 109 Gt y−1. The largest improvement is found in modelled surface snowmelt, which now compares well with satellite and weather station observations. For the high-resolution (∼ 5.5 km) AP simulation, results remain comparable to earlier studies. The updated model provides a new, high-resolution data set of the contemporary near-surface climate and SMB of the AIS; this model version will be used for future climate scenario projections in a forthcoming study.

Published
2018

49. An Integrated View of Greenland Ice Sheet Mass Changes Based on Models and Satellite Observations

Author

Mottram, Ruth, primary, B. Simonsen, Sebastian, additional, Høyer Svendsen, Synne, additional, Barletta, Valentina R., additional, Sandberg Sørensen, Louise, additional, Nagler, Thomas, additional, Wuite, Jan, additional, Groh, Andreas, additional, Horwath, Martin, additional, Rosier, Job, additional, Solgaard, Anne, additional, Hvidberg, Christine S., additional, and Forsberg, Rene, additional

Published
2019
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50. An integrated view of greenland ice sheet mass changes based on models and satellite observations

Author

Mottram, Ruth, Simonsen, Sebastian B., Svendsen, Synne Høyer, Barletta, Valentina R., Sørensen, Louise Sandberg, Nagler, Thomas, Wuite, Jan, Groh, Andreas, Horwath, Martin, Rosier, Job, Solgaard, Anne, Hvidberg, Christine S., Forsberg, Rene, Mottram, Ruth, Simonsen, Sebastian B., Svendsen, Synne Høyer, Barletta, Valentina R., Sørensen, Louise Sandberg, Nagler, Thomas, Wuite, Jan, Groh, Andreas, Horwath, Martin, Rosier, Job, Solgaard, Anne, Hvidberg, Christine S., and Forsberg, Rene

Abstract

The Greenland ice sheet is a major contributor to sea level rise, adding on average 0.47 ± 0.23 mm year-1 to global mean sea level between 1991 and 2015. The cryosphere as a whole has contributed around 45% of observed global sea level rise since 1993. Understanding the present-day state of the Greenland ice sheet is therefore vital for understanding the processes controlling the modern-day rates of sea level change and for making projections of sea level rise into the future. Here, we provide an overview of the current state of the mass budget of Greenland based on a diverse range of remote sensing observations to produce the essential climate variables (ECVs) of ice velocity, surface elevation change, grounding line location, calving front location, and gravimetric mass balance as well as numerical modelling that together build a consistent picture of a shrinking ice sheet. We also combine these observations with output from a regional climate model and from an ice sheet model to gain insight into existing biases in ice sheet dynamics and surface mass balance processes. Observations show surface lowering across virtually all regions of the ice sheet and at some locations up to -2.65 m year-1 between 1995 and 2017 based on radar altimetry analysis. In addition, calving fronts at 28 study sites, representing a sample of typical glaciers, have retreated all around Greenland since the 1990s and in only two out of 28 study locations have they remained stable. During the same period, two of five floating ice shelves have collapsed while the locations of grounding lines at the remaining three floating ice shelves have remained stable over the observation period. In a detailed case study with a fracture model at Petermann glacier, we demonstrate the potential sensitivity of these floating ice shelves to future warming. GRACE gravimetrically-derived mass balance (GMB) data shows that overall Greenland has lost 255 ± 15 Gt year-1 of ice o

Published
2019

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