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254 results on '"Schlegel, Nicole‐Jeanne"'

1. Harnessing Feature Clustering For Enhanced Anomaly Detection With Variational Autoencoder And Dynamic Threshold

Author

Ale, Tolulope, Schlegel, Nicole-Jeanne, and Janeja, Vandana P.

Subjects
Computer Science - Machine Learning, Computer Science - Information Retrieval
Abstract

We introduce an anomaly detection method for multivariate time series data with the aim of identifying critical periods and features influencing extreme climate events like snowmelt in the Arctic. This method leverages the Variational Autoencoder (VAE) integrated with dynamic thresholding and correlation-based feature clustering. This framework enhances the VAE's ability to identify localized dependencies and learn the temporal relationships in climate data, thereby improving the detection of anomalies as demonstrated by its higher F1-score on benchmark datasets. The study's main contributions include the development of a robust anomaly detection method, improving feature representation within VAEs through clustering, and creating a dynamic threshold algorithm for localized anomaly detection. This method offers explainability of climate anomalies across different regions., Comment: This work was presented at the 2024 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2024, 07-12 July 2024, Athens, Greece

Published
2024

2. The case for a multi-channel polarization sensitive LIDAR for investigation of insolation-driven ices and atmospheres

Author

Brown, Adrian J., Videen, Gorden, Zubko, Evgenij, Heavens, Nicholas, Schlegel, Nicole-Jeanne, Becerra, Patricio, Choi, Young-Jun, Meyer, Colin R., Harrison, Tanya N., Hayne, Paul, Obbard, Rachel W., Michaels, Tim, Wolff, Michael J., Guzewich, Scott, Hu, Yongxiang, Newman, Claire, Grund, Christian J., Sim, Chae Kyung, Buhler, Peter B., Landis, Margaret E., Stubbs, Timothy J., Spiga, Aymeric, and Jha, Devanshu

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

All LIDAR instruments are not the same, and advancement of LIDAR technology requires an ongoing interest and demand from the community to foster further development of the required components. The purpose of this paper is to make the community aware of the need for further technical development, and the potential payoff of investing experimental time, money and thought into the next generation of LIDARs., Comment: 12 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:1406.0030

Published
2020

3. Projected land ice contributions to twenty-first-century sea level rise

Author

Edwards, Tamsin L, Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C, Slater, Donald A, Turner, Fiona E, Smith, Christopher J, McKenna, Christine M, Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M, Larour, Eric, Lipscomb, William H, Payne, Antony J, Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K, Gladstone, Rupert, Golledge, Nicholas R, Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J, Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le clec’h, Sébastien, Lee, Victoria, Leguy, Gunter R, Little, Christopher M, Lowry, Daniel P, Malles, Jan-Hendrik, Martin, Daniel F, Maussion, Fabien, Morlighem, Mathieu, O’Neill, James F, Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F, Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R, Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S, Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D, Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Subjects
Earth Sciences, Physical Geography and Environmental Geoscience, Climate Action, General Science & Technology
Abstract

The land ice contribution to global mean sea level rise has not yet been predicted1 using ice sheet and glacier models for the latest set of socio-economic scenarios, nor using coordinated exploration of uncertainties arising from the various computer models involved. Two recent international projects generated a large suite of projections using multiple models2-8, but primarily used previous-generation scenarios9 and climate models10, and could not fully explore known uncertainties. Here we estimate probability distributions for these projections under the new scenarios11,12 using statistical emulation of the ice sheet and glacier models. We find that limiting global warming to 1.5 degrees Celsius would halve the land ice contribution to twenty-first-century sea level rise, relative to current emissions pledges. The median decreases from 25 to 13 centimetres sea level equivalent (SLE) by 2100, with glaciers responsible for half the sea level contribution. The projected Antarctic contribution does not show a clear response to the emissions scenario, owing to uncertainties in the competing processes of increasing ice loss and snowfall accumulation in a warming climate. However, under risk-averse (pessimistic) assumptions, Antarctic ice loss could be five times higher, increasing the median land ice contribution to 42 centimetres SLE under current policies and pledges, with the 95th percentile projection exceeding half a metre even under 1.5 degrees Celsius warming. This would severely limit the possibility of mitigating future coastal flooding. Given this large range (between 13 centimetres SLE using the main projections under 1.5 degrees Celsius warming and 42 centimetres SLE using risk-averse projections under current pledges), adaptation planning for twenty-first-century sea level rise must account for a factor-of-three uncertainty in the land ice contribution until climate policies and the Antarctic response are further constrained.

Published
2021

4. Understanding of Contemporary Regional Sea‐Level Change and the Implications for the Future

Author

Hamlington, Benjamin D, Gardner, Alex S, Ivins, Erik, Lenaerts, Jan TM, Reager, JT, Trossman, David S, Zaron, Edward D, Adhikari, Surendra, Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D, Bekaert, David PS, Blewitt, Geoffrey, Caron, Lambert, Chambers, Don P, Chandanpurkar, Hrishikesh A, Christianson, Knut, Csatho, Beata, Cullather, Richard I, DeConto, Robert M, Fasullo, John T, Frederikse, Thomas, Freymueller, Jeffrey T, Gilford, Daniel M, Girotto, Manuela, Hammond, William C, Hock, Regine, Holschuh, Nicholas, Kopp, Robert E, Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X, Nerem, R Steven, Nias, Isabel J, Nieves, Veronica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G, Ray, Richard D, Rounce, David R, Schlegel, Nicole‐Jeanne, Seroussi, Hélène, Shirzaei, Manoochehr, Sweet, William V, Velicogna, Isabella, Vinogradova, Nadya, Wahl, Thomas, Wiese, David N, and Willis, Michael J

Subjects
Climate Action, sea level, satellite observations, remote sensing, Physical Sciences, Earth Sciences, Engineering, Meteorology & Atmospheric Sciences
Abstract

Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea-level observing system, the knowledge of regional sea-level change has advanced dramatically in recent years. Satellite measurements coupled with in situ observations have allowed for comprehensive study and improved understanding of the diverse set of drivers that lead to variations in sea level in space and time. Despite the advances, gaps in the understanding of contemporary sea-level change remain and inhibit the ability to predict how the relevant processes may lead to future change. These gaps arise in part due to the complexity of the linkages between the drivers of sea-level change. Here we review the individual processes which lead to sea-level change and then describe how they combine and vary regionally. The intent of the paper is to provide an overview of the current state of understanding of the processes that cause regional sea-level change and to identify and discuss limitations and uncertainty in our understanding of these processes. Areas where the lack of understanding or gaps in knowledge inhibit the ability to provide the needed information for comprehensive planning efforts are of particular focus. Finally, a goal of this paper is to highlight the role of the expanded sea-level observation network-particularly as related to satellite observations-in the improved scientific understanding of the contributors to regional sea-level change.

Published
2020

5. Projecting Antarctica's contribution to future sea level rise from basal ice shelf melt using linear response functions of 16 ice sheet models (LARMIP-2)

Author

Levermann, Anders, Winkelmann, Ricarda, Albrecht, Torsten, Goelzer, Heiko, Golledge, Nicholas R, Greve, Ralf, Huybrechts, Philippe, Jordan, Jim, Leguy, Gunter, Martin, Daniel, Morlighem, Mathieu, Pattyn, Frank, Pollard, David, Quiquet, Aurelien, Rodehacke, Christian, Seroussi, Helene, Sutter, Johannes, Zhang, Tong, Van Breedam, Jonas, Calov, Reinhard, DeConto, Robert, Dumas, Christophe, Garbe, Julius, Gudmundsson, G Hilmar, Hoffman, Matthew J, Humbert, Angelika, Kleiner, Thomas, Lipscomb, William H, Meinshausen, Malte, Ng, Esmond, Nowicki, Sophie MJ, Perego, Mauro, Price, Stephen F, Saito, Fuyuki, Schlegel, Nicole-Jeanne, Sun, Sainan, and van de Wal, Roderik SW

Subjects
Earth Sciences, Oceanography, Physical Geography and Environmental Geoscience, Geology, Climate Action, Atmospheric Sciences, Climate change science, Geoinformatics
Abstract

The sea level contribution of the Antarctic ice sheet constitutes a large uncertainty in future sea level projections. Here we apply a linear response theory approach to 16 state-of-the-art ice sheet models to estimate the Antarctic ice sheet contribution from basal ice shelf melting within the 21st century. The purpose of this computation is to estimate the uncertainty of Antarctica's future contribution to global sea level rise that arises from large uncertainty in the oceanic forcing and the associated ice shelf melting. Ice shelf melting is considered to be a major if not the largest perturbation of the ice sheet's flow into the ocean. However, by computing only the sea level contribution in response to ice shelf melting, our study is neglecting a number of processes such as surface-mass-balance-related contributions. In assuming linear response theory, we are able to capture complex temporal responses of the ice sheets, but we neglect any self-dampening or self-amplifying processes. This is particularly relevant in situations in which an instability is dominating the ice loss. The results obtained here are thus relevant, in particular wherever the ice loss is dominated by the forcing as opposed to an internal instability, for example in strong ocean warming scenarios. In order to allow for comparison the methodology was chosen to be exactly the same as in an earlier study (Levermann et al., 2014) but with 16 instead of 5 ice sheet models. We include uncertainty in the atmospheric warming response to carbon emissions (full range of CMIP5 climate model sensitivities), uncertainty in the oceanic transport to the Southern Ocean (obtained from the time-delayed and scaled oceanic subsurface warming in CMIP5 models in relation to the global mean surface warming), and the observed range of responses of basal ice shelf melting to oceanic warming outside the ice shelf cavity. This uncertainty in basal ice shelf melting is then convoluted with the linear response functions of each of the 16 ice sheet models to obtain the ice flow response to the individual global warming path. The model median for the observational period from 1992 to 2017 of the ice loss due to basal ice shelf melting is 10.2 mm, with a likely range between 5.2 and 21.3 mm. For the same period the Antarctic ice sheet lost mass equivalent to 7.4mm of global sea level rise, with a standard deviation of 3.7mm (Shepherd et al., 2018) including all processes, especially surface-mass-balance changes. For the unabated warming path, Representative Concentration Pathway 8.5 (RCP8.5), we obtain a median contribution of the Antarctic ice sheet to global mean sea level rise from basal ice shelf melting within the 21st century of 17 cm, with a likely range (66th percentile around the mean) between 9 and 36 cm and a very likely range (90th percentile around the mean) between 6 and 58 cm. For the RCP2.6 warming path, which will keep the global mean temperature below 2 °C of global warming and is thus consistent with the Paris Climate Agreement, the procedure yields a median of 13 cm of global mean sea level contribution. The likely range for the RCP2.6 scenario is between 7 and 24 cm, and the very likely range is between 4 and 37 cm. The structural uncertainties in the method do not allow for an interpretation of any higher uncertainty percentiles.We provide projections for the five Antarctic regions and for each model and each scenario separately. The rate of sea level contribution is highest under the RCP8.5 scenario. The maximum within the 21st century of the median value is 4 cm per decade, with a likely range between 2 and 9 cm per decade and a very likely range between 1 and 14 cm per decade.

Published
2020

8. Exploration of Antarctic Ice Sheet 100-year contribution to sea level rise and associated model uncertainties using the ISSM framework

Author

Schlegel, Nicole-Jeanne, Seroussi, Helene, Schodlok, Michael P, Larour, Eric Y, Boening, Carmen, Limonadi, Daniel, Watkins, Michael M, Morlighem, Mathieu, and van den Broeke, Michiel R

Subjects
Climate Action, Oceanography, Physical Geography and Environmental Geoscience, Meteorology & Atmospheric Sciences
Abstract

Estimating the future evolution of the Antarctic Ice Sheet (AIS) is critical for improving future sea level rise (SLR) projections. Numerical ice sheet models are invaluable tools for bounding Antarctic vulnerability; yet, few continental-scale projections of century-scale AIS SLR contribution exist, and those that do vary by up to an order of magnitude. This is partly because model projections of future sea level are inherently uncertain and depend largely on the model's boundary conditions and climate forcing, which themselves are unknown due to the uncertainty in the projections of future anthropogenic emissions and subsequent climate response. Here, we aim to improve the understanding of how uncertainties in model forcing and boundary conditions affect ice sheet model simulations. With use of sampling techniques embedded within the Ice Sheet System Model (ISSM) framework, we assess how uncertainties in snow accumulation, ocean-induced melting, ice viscosity, basal friction, bedrock elevation, and the presence of ice shelves impact continental-scale 100-year model simulations of AIS future sea level contribution. Overall, we find that AIS sea level contribution is strongly affected by grounding line retreat, which is driven by the magnitude of ice shelf basal melt rates and by variations in bedrock topography. In addition, we find that over 1.2 m of AIS global mean sea level contribution over the next century is achievable, but not likely, as it is tenable only in response to unrealistically large melt rates and continental ice shelf collapse. Regionally, we find that under our most extreme 100-year warming experiment generalized for the entire ice sheet, the Amundsen Sea sector is the most significant source of model uncertainty (1032 mm 6σ spread) and the region with the largest potential for future sea level contribution (297 mm). In contrast, under a more plausible forcing informed regionally by literature and model sensitivity studies, the Ronne basin has a greater potential for local increases in ice shelf basal melt rates. As a result, under this more likely realization, where warm waters reach the continental shelf under the Ronne ice shelf, it is the Ronne basin, particularly the Evans and Rutford ice streams, that are the greatest contributors to potential SLR (161 mm) and to simulation uncertainty (420 mm 6spread).

Published
2018

9. Correction to: Firn on ice sheets (Nature Reviews Earth & Environment, (2024), 5, 2, (79-99), 10.1038/s43017-023-00507-9)

Author

Amory, Charles, Buizert, Christo, Buzzard, Sammie, Clerx, Nicole, Culberg, Riley, Dey, Rahul, Drews, Reinhard, Dunmire, Devon, Eayrs, Clare, Hansen, Nicolaj, Humbert, Angelika, Kaitheri, Athul, Keegan, Kaitlin, Kuipers Munneke, Peter, Lhermitte, Stef, Mair, Doug, McDowell, Ian, Mejia, Jessica, Meyer, Colin R., Morris, Elizabeth, Moser, Dorothea, Oraschewski, Falk M., Pearce, Emma, Schlegel, Nicole Jeanne, Schultz, Timm, Simonsen, Sebastian B., Stevens, C. Max, Thomas, Elizabeth R., Thompson-Munson, Megan, Wever, Nander, Amory, Charles, Buizert, Christo, Buzzard, Sammie, Clerx, Nicole, Culberg, Riley, Dey, Rahul, Drews, Reinhard, Dunmire, Devon, Eayrs, Clare, Hansen, Nicolaj, Humbert, Angelika, Kaitheri, Athul, Keegan, Kaitlin, Kuipers Munneke, Peter, Lhermitte, Stef, Mair, Doug, McDowell, Ian, Mejia, Jessica, Meyer, Colin R., Morris, Elizabeth, Moser, Dorothea, Oraschewski, Falk M., Pearce, Emma, Schlegel, Nicole Jeanne, Schultz, Timm, Simonsen, Sebastian B., Stevens, C. Max, Thomas, Elizabeth R., Thompson-Munson, Megan, and Wever, Nander

Abstract

Correction to: Nature Reviews Earth & Environmenthttps://doi.org/10.1038/s43017-023-00507-9, published online 23 January 2024. In the version of the article initially published, in Fig. 5, under “Radar altimeter”, “O(16–160 m)” previously read “O(16–160 km)”. This has now been corrected in the HTML and PDF versions of the article.

Published
2024

10. Correction to: Firn on ice sheets (Nature Reviews Earth & Environment, (2024), 5, 2, (79-99), 10.1038/s43017-023-00507-9)

Author

Sub Dynamics Meteorology, Marine and Atmospheric Research, Amory, Charles, Buizert, Christo, Buzzard, Sammie, Clerx, Nicole, Culberg, Riley, Dey, Rahul, Drews, Reinhard, Dunmire, Devon, Eayrs, Clare, Hansen, Nicolaj, Humbert, Angelika, Kaitheri, Athul, Keegan, Kaitlin, Kuipers Munneke, Peter, Lhermitte, Stef, Mair, Doug, McDowell, Ian, Mejia, Jessica, Meyer, Colin R., Morris, Elizabeth, Moser, Dorothea, Oraschewski, Falk M., Pearce, Emma, Schlegel, Nicole Jeanne, Schultz, Timm, Simonsen, Sebastian B., Stevens, C. Max, Thomas, Elizabeth R., Thompson-Munson, Megan, Wever, Nander, Sub Dynamics Meteorology, Marine and Atmospheric Research, Amory, Charles, Buizert, Christo, Buzzard, Sammie, Clerx, Nicole, Culberg, Riley, Dey, Rahul, Drews, Reinhard, Dunmire, Devon, Eayrs, Clare, Hansen, Nicolaj, Humbert, Angelika, Kaitheri, Athul, Keegan, Kaitlin, Kuipers Munneke, Peter, Lhermitte, Stef, Mair, Doug, McDowell, Ian, Mejia, Jessica, Meyer, Colin R., Morris, Elizabeth, Moser, Dorothea, Oraschewski, Falk M., Pearce, Emma, Schlegel, Nicole Jeanne, Schultz, Timm, Simonsen, Sebastian B., Stevens, C. Max, Thomas, Elizabeth R., Thompson-Munson, Megan, and Wever, Nander

Published
2024

14. Insights into the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertainty

Author

Seroussi, Hélène, primary, Verjans, Vincent, additional, Nowicki, Sophie, additional, Payne, Antony J., additional, Goelzer, Heiko, additional, Lipscomb, William H., additional, Abe-Ouchi, Ayako, additional, Agosta, Cécile, additional, Albrecht, Torsten, additional, Asay-Davis, Xylar, additional, Barthel, Alice, additional, Calov, Reinhard, additional, Cullather, Richard, additional, Dumas, Christophe, additional, Galton-Fenzi, Benjamin K., additional, Gladstone, Rupert, additional, Golledge, Nicholas R., additional, Gregory, Jonathan M., additional, Greve, Ralf, additional, Hattermann, Tore, additional, Hoffman, Matthew J., additional, Humbert, Angelika, additional, Huybrechts, Philippe, additional, Jourdain, Nicolas C., additional, Kleiner, Thomas, additional, Larour, Eric, additional, Leguy, Gunter R., additional, Lowry, Daniel P., additional, Little, Chistopher M., additional, Morlighem, Mathieu, additional, Pattyn, Frank, additional, Pelle, Tyler, additional, Price, Stephen F., additional, Quiquet, Aurélien, additional, Reese, Ronja, additional, Schlegel, Nicole-Jeanne, additional, Shepherd, Andrew, additional, Simon, Erika, additional, Smith, Robin S., additional, Straneo, Fiammetta, additional, Sun, Sainan, additional, Trusel, Luke D., additional, Van Breedam, Jonas, additional, Van Katwyk, Peter, additional, van de Wal, Roderik S. W., additional, Winkelmann, Ricarda, additional, Zhao, Chen, additional, Zhang, Tong, additional, and Zwinger, Thomas, additional

Published
2023
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15. Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century

Author

Briner, Jason P., Cuzzone, Joshua K., Badgeley, Jessica A., Young, Nicolás E., Steig, Eric J., Morlighem, Mathieu, Schlegel, Nicole-Jeanne, Hakim, Gregory J., Schaefer, Joerg M., Johnson, Jesse V., Lesnek, Alia J., Thomas, Elizabeth K., Allan, Estelle, Bennike, Ole, Cluett, Allison A., Csatho, Beata, de Vernal, Anne, Downs, Jacob, Larour, Eric, and Nowicki, Sophie

Published
2020
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23. Insights on the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertainty

Author

Seroussi, Hélène, primary, Verjans, Vincent, additional, Nowicki, Sophie, additional, Payne, Antony J., additional, Goelzer, Heiko, additional, Lipscomb, William H., additional, Abe Ouchi, Ayako, additional, Agosta, Cécile, additional, Albrecht, Torsten, additional, Asay-Davis, Xylar, additional, Barthel, Alice, additional, Calov, Reinhard, additional, Cullather, Richard, additional, Dumas, Christophe, additional, Galton-Fenzi, Benjamin K., additional, Gladstone, Rupert, additional, Golledge, Nicholas R., additional, Gregory, Jonathan M., additional, Greve, Ralf, additional, Hatterman, Tore, additional, Hoffman, Matthew J., additional, Humbert, Angelika, additional, Huybrechts, Philippe, additional, Jourdain, Nicolas C., additional, Kleiner, Thomas, additional, Larour, Eric, additional, Leguy, Gunter R., additional, Lowry, Daniel P., additional, Little, Chistopher M., additional, Morlighem, Mathieu, additional, Pattyn, Frank, additional, Pelle, Tyler, additional, Price, Stephen F., additional, Quiquet, Aurélien, additional, Reese, Ronja, additional, Schlegel, Nicole-Jeanne, additional, Shepherd, Andrew, additional, Simon, Erika, additional, Smith, Robin S., additional, Straneo, Fiametta, additional, Sun, Sainan, additional, Trusel, Luke D., additional, Van Breedam, Jonas, additional, Van Katwyk, Peter, additional, van de Wal, Roderik S. W., additional, Winkelmann, Ricarda, additional, Zhao, Chen, additional, Zhang, Tong, additional, and Zwinger, Thomas, additional

Published
2023
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26. Laser altimetry reveals significant decadal variability of Siple Coast ice streams, West Antarctica in 1997-2023

Author

Csatho, Beata, Schenk, Toni, Narkevic, Ash, van der Veen, Cornelis, Schlegel, Nicole_Jeanne, and Medley, Brooke

Abstract

The Siple Coast ice streams draining the West Antarctica Ice Sheet (WAIS) into the Ross Ice Shelf exhibit significant decadal to millennium-scale variability, including the complete shutdown of the Kamb Ice Stream, suggesting a complex response to a warming climate. Here we present a new elevation change record derived from laser altimetry observations using the Surface Elevation Reconstruction And Change detection (SERAC) method. The high temporal resolution ICESat (2003-2009) and ICESat-2 (2018-present) records were augmented with airborne laser altimetry observations and partitioned into changes due to surface processes - estimated by the GSFC and GEMB FDMs - and ice dynamics. Based on the dynamic thickness change time series, we distinguish local, rapid changes due to active hydrological systems, such as filling and draining subglacial lakes, and regional dynamic thickness changes associated with ice stream slow-down and speed up, which could signal impending stagnation or reactivation. The newly detected rapid local thickness changes indicate that the active subglacial hydrological network extends farther inland to the interior of WAIS than previously thought. Moreover, subglacial lake activity is detected along the Mercer Ice Stream across the Transantarctic Mountains, a pathway connecting the WAIS and EIAS. We further investigate dynamic thickness change patterns by examining ice velocity changes and inferring changes in basal conditions by reconstructing subglacial water routing from REMA DEMs fused with altimetry. Our results provide crucial insight into the processes controlling the Siple Coast ice streams, a vulnerable region with a considerable potential for future sea level rise., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

27. Uncertainty characterisation in ice-sheet mass balance estimates and intercomparisons

Author

Horwath, Martin, Rignot, Eric, Smith, Benjamin E., Schlegel, Nicole-Jeanne, Shepherd, Andrew, Ivins, Erik, and Otosaka, Inès

Abstract

Ice-sheet mass balance is commonly estimated by the input output method, the altimetry method, the gravimetry method, or their combination. All of them are subject to uncertainties, e.g. due to limitations in sampling and resolution, residual calibration issues, and corrections from geophysical models involved. Error budgets have been built for each of them. Intercomparison exercises have been conducted to analyze residual uncertainties, to learn about the implications this may have on our understanding of physical processes controlling the mass balance, and to generate compound estimates. Here we review approaches and discussions on uncertainty characterization related to the Ice-sheet Mass Balance Intercomparison Exercise (IMBIE). We discuss the following problems: First, the target mass balance estimates embrace different temporal scales from monthly to multi-decadal, and embrace different mass balance representations, either as rates of mass change or as mass anomalies w.r.t. a reference state or as volume change converted into mass change. The intercomparison needs to accommodate these representations in a consistent uncertainty characterization framework, and the organizers need to consider what compromises are needed and acceptable to simplify and unify the uncertainty characterization tasks posed to the contributors to the intercomparison. Second, compound estimates need to weight the different contributions. The intercomparison needs to decide how assessed uncertainties should affect the definition of weights and hence of the compound estimates. Discussions on these and other aspects are ongoing within the IMBIE Working Group on Error Budget. Soliciting feedback from the wider community is one aim of this presentation., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

31. Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020

Author

Otosaka, Inès N., primary, Shepherd, Andrew, additional, Ivins, Erik R., additional, Schlegel, Nicole-Jeanne, additional, Amory, Charles, additional, van den Broeke, Michiel R., additional, Horwath, Martin, additional, Joughin, Ian, additional, King, Michalea D., additional, Krinner, Gerhard, additional, Nowicki, Sophie, additional, Payne, Anthony J., additional, Rignot, Eric, additional, Scambos, Ted, additional, Simon, Karen M., additional, Smith, Benjamin E., additional, Sørensen, Louise S., additional, Velicogna, Isabella, additional, Whitehouse, Pippa L., additional, A, Geruo, additional, Agosta, Cécile, additional, Ahlstrøm, Andreas P., additional, Blazquez, Alejandro, additional, Colgan, William, additional, Engdahl, Marcus E., additional, Fettweis, Xavier, additional, Forsberg, Rene, additional, Gallée, Hubert, additional, Gardner, Alex, additional, Gilbert, Lin, additional, Gourmelen, Noel, additional, Groh, Andreas, additional, Gunter, Brian C., additional, Harig, Christopher, additional, Helm, Veit, additional, Khan, Shfaqat Abbas, additional, Kittel, Christoph, additional, Konrad, Hannes, additional, Langen, Peter L., additional, Lecavalier, Benoit S., additional, Liang, Chia-Chun, additional, Loomis, Bryant D., additional, McMillan, Malcolm, additional, Melini, Daniele, additional, Mernild, Sebastian H., additional, Mottram, Ruth, additional, Mouginot, Jeremie, additional, Nilsson, Johan, additional, Noël, Brice, additional, Pattle, Mark E., additional, Peltier, William R., additional, Pie, Nadege, additional, Roca, Mònica, additional, Sasgen, Ingo, additional, Save, Himanshu V., additional, Seo, Ki-Weon, additional, Scheuchl, Bernd, additional, Schrama, Ernst J. O., additional, Schröder, Ludwig, additional, Simonsen, Sebastian B., additional, Slater, Thomas, additional, Spada, Giorgio, additional, Sutterley, Tyler C., additional, Vishwakarma, Bramha Dutt, additional, van Wessem, Jan Melchior, additional, Wiese, David, additional, van der Wal, Wouter, additional, and Wouters, Bert, additional

Published
2023
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32. Insights into the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertainty

Author

Seroussi, Hélène, Verjans, Vincent, Nowicki, Sophie, Payne, Antony J., Goelzer, Heiko, Lipscomb, William H., Abe-Ouchi, Ayako, Agosta, Cécile, Albrecht, Torsten, Asay-Davis, Xylar, Barthel, Alice, Calov, Reinhard, Cullather, Richard, Dumas, Christophe, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Gregory, Jonathan M., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huybrechts, Philippe, Jourdain, Nicolas C., Kleiner, Thomas, Larour, Eric, Leguy, Gunter R., Lowry, Daniel P., Little, Chistopher M., Morlighem, Mathieu, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Reese, Ronja, Schlegel, Nicole Jeanne, Shepherd, Andrew, Simon, Erika, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Trusel, Luke D., Van Breedam, Jonas, Van Katwyk, Peter, van de Wal, Roderik S.W., Winkelmann, Ricarda, Zhao, Chen, Zhang, Tong, Zwinger, Thomas, Seroussi, Hélène, Verjans, Vincent, Nowicki, Sophie, Payne, Antony J., Goelzer, Heiko, Lipscomb, William H., Abe-Ouchi, Ayako, Agosta, Cécile, Albrecht, Torsten, Asay-Davis, Xylar, Barthel, Alice, Calov, Reinhard, Cullather, Richard, Dumas, Christophe, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Gregory, Jonathan M., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huybrechts, Philippe, Jourdain, Nicolas C., Kleiner, Thomas, Larour, Eric, Leguy, Gunter R., Lowry, Daniel P., Little, Chistopher M., Morlighem, Mathieu, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Reese, Ronja, Schlegel, Nicole Jeanne, Shepherd, Andrew, Simon, Erika, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Trusel, Luke D., Van Breedam, Jonas, Van Katwyk, Peter, van de Wal, Roderik S.W., Winkelmann, Ricarda, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Abstract

The Antarctic Ice Sheet represents the largest source of uncertainty in future sea level rise projections, with a contribution to sea level by 2100 ranging from −5 to 43 cm of sea level equivalent under high carbon emission scenarios estimated by the recent Ice Sheet Model Intercomparison for CMIP6 (ISMIP6). ISMIP6 highlighted the different behaviors of the East and West Antarctic ice sheets, as well as the possible role of increased surface mass balance in offsetting the dynamic ice loss in response to changing oceanic conditions in ice shelf cavities. However, the detailed contribution of individual glaciers, as well as the partitioning of uncertainty associated with this ensemble, have not yet been investigated. Here, we analyze the ISMIP6 results for high carbon emission scenarios, focusing on key glaciers around the Antarctic Ice Sheet, and we quantify their projected dynamic mass loss, defined here as mass loss through increased ice discharge into the ocean in response to changing oceanic conditions. We highlight glaciers contributing the most to sea level rise, as well as their vulnerability to changes in oceanic conditions. We then investigate the different sources of uncertainty and their relative role in projections, for the entire continent and for key individual glaciers. We show that, in addition to Thwaites and Pine Island glaciers in West Antarctica, Totten and Moscow University glaciers in East Antarctica present comparable future dynamic mass loss and high sensitivity to ice shelf basal melt. The overall uncertainty in additional dynamic mass loss in response to changing oceanic conditions, compared to a scenario with constant oceanic conditions, is dominated by the choice of ice sheet model, accounting for 52 % of the total uncertainty of the Antarctic dynamic mass loss in 2100. Its relative role for the most dynamic glaciers varies between 14 % for MacAyeal and Whillans ice streams and 56 % for Pine Island Glacier at the end of the century. The

Published
2023

33. Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020

Author

Otosaka, Inès N., Shepherd, Andrew, Ivins, Erik R., Schlegel, Nicole Jeanne, Amory, Charles, Van Den Broeke, Michiel R., Horwath, Martin, Joughin, Ian, King, Michalea D., Krinner, Gerhard, Nowicki, Sophie, Payne, Anthony J., Rignot, Eric, Scambos, Ted, Simon, Karen M., Smith, Benjamin E., Sørensen, Louise S., Velicogna, Isabella, Whitehouse, Pippa L., Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas P., Blazquez, Alejandro, Colgan, William, Engdahl, Marcus E., Fettweis, Xavier, Forsberg, Rene, Gallée, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian C., Harig, Christopher, Helm, Veit, Khan, Shfaqat Abbas, Kittel, Christoph, Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit S., Liang, Chia Chun, Loomis, Bryant D., McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian H., Mottram, Ruth, Mouginot, Jeremie, Nilsson, Johan, Noël, Brice, Pattle, Mark E., Peltier, William R., Pie, Nadege, Roca, Mònica, Sasgen, Ingo, Save, Himanshu V., Seo, Ki Weon, Scheuchl, Bernd, Schrama, Ernst J.O., Schröder, Ludwig, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler C., Vishwakarma, Bramha Dutt, Van Wessem, Jan Melchior, Wiese, David, Van Der Wal, Wouter, Wouters, Bert, Otosaka, Inès N., Shepherd, Andrew, Ivins, Erik R., Schlegel, Nicole Jeanne, Amory, Charles, Van Den Broeke, Michiel R., Horwath, Martin, Joughin, Ian, King, Michalea D., Krinner, Gerhard, Nowicki, Sophie, Payne, Anthony J., Rignot, Eric, Scambos, Ted, Simon, Karen M., Smith, Benjamin E., Sørensen, Louise S., Velicogna, Isabella, Whitehouse, Pippa L., Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas P., Blazquez, Alejandro, Colgan, William, Engdahl, Marcus E., Fettweis, Xavier, Forsberg, Rene, Gallée, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian C., Harig, Christopher, Helm, Veit, Khan, Shfaqat Abbas, Kittel, Christoph, Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit S., Liang, Chia Chun, Loomis, Bryant D., McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian H., Mottram, Ruth, Mouginot, Jeremie, Nilsson, Johan, Noël, Brice, Pattle, Mark E., Peltier, William R., Pie, Nadege, Roca, Mònica, Sasgen, Ingo, Save, Himanshu V., Seo, Ki Weon, Scheuchl, Bernd, Schrama, Ernst J.O., Schröder, Ludwig, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler C., Vishwakarma, Bramha Dutt, Van Wessem, Jan Melchior, Wiese, David, Van Der Wal, Wouter, and Wouters, Bert

Abstract

Ice losses from the Greenland and Antarctic ice sheets have accelerated since the 1990s, accounting for a significant increase in the global mean sea level. Here, we present a new 29-year record of ice sheet mass balance from 1992 to 2020 from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE). We compare and combine 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field. Between 1992 and 2020, the ice sheets contributed 21.0±1.9g€¯mm to global mean sea level, with the rate of mass loss rising from 105g€¯Gtg€¯yr-1 between 1992 and 1996 to 372g€¯Gtg€¯yr-1 between 2016 and 2020. In Greenland, the rate of mass loss is 169±9g€¯Gtg€¯yr-1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86g€¯Gtg€¯yr-1 in 2017 to 444g€¯Gtg€¯yr-1 in 2019 due to large variability in surface mass balance. In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9g€¯Gtg€¯yr-1) and, to a lesser extent, from the Antarctic Peninsula (13±5g€¯Gtg€¯yr-1). East Antarctica remains close to a state of balance, with a small gain of 3±15g€¯Gtg€¯yr-1, but is the most uncertain component of Antarctica's mass balance. The dataset is publicly available at 10.5285/77B64C55-7166-4A06-9DEF-2E400398E452 (IMBIE Team, 2021).

Published
2023

34. Insights into the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertainty

Author

Sub Dynamics Meteorology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Seroussi, Hélène, Verjans, Vincent, Nowicki, Sophie, Payne, Antony J., Goelzer, Heiko, Lipscomb, William H., Abe-Ouchi, Ayako, Agosta, Cécile, Albrecht, Torsten, Asay-Davis, Xylar, Barthel, Alice, Calov, Reinhard, Cullather, Richard, Dumas, Christophe, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Gregory, Jonathan M., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huybrechts, Philippe, Jourdain, Nicolas C., Kleiner, Thomas, Larour, Eric, Leguy, Gunter R., Lowry, Daniel P., Little, Chistopher M., Morlighem, Mathieu, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Reese, Ronja, Schlegel, Nicole Jeanne, Shepherd, Andrew, Simon, Erika, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Trusel, Luke D., Van Breedam, Jonas, Van Katwyk, Peter, van de Wal, Roderik S.W., Winkelmann, Ricarda, Zhao, Chen, Zhang, Tong, Zwinger, Thomas, Sub Dynamics Meteorology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Seroussi, Hélène, Verjans, Vincent, Nowicki, Sophie, Payne, Antony J., Goelzer, Heiko, Lipscomb, William H., Abe-Ouchi, Ayako, Agosta, Cécile, Albrecht, Torsten, Asay-Davis, Xylar, Barthel, Alice, Calov, Reinhard, Cullather, Richard, Dumas, Christophe, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Gregory, Jonathan M., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huybrechts, Philippe, Jourdain, Nicolas C., Kleiner, Thomas, Larour, Eric, Leguy, Gunter R., Lowry, Daniel P., Little, Chistopher M., Morlighem, Mathieu, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Reese, Ronja, Schlegel, Nicole Jeanne, Shepherd, Andrew, Simon, Erika, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Trusel, Luke D., Van Breedam, Jonas, Van Katwyk, Peter, van de Wal, Roderik S.W., Winkelmann, Ricarda, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Published
2023

35. Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020

Author

Sub Dynamics Meteorology, Structural geology and EM, Marine and Atmospheric Research, Otosaka, Inès N., Shepherd, Andrew, Ivins, Erik R., Schlegel, Nicole Jeanne, Amory, Charles, Van Den Broeke, Michiel R., Horwath, Martin, Joughin, Ian, King, Michalea D., Krinner, Gerhard, Nowicki, Sophie, Payne, Anthony J., Rignot, Eric, Scambos, Ted, Simon, Karen M., Smith, Benjamin E., Sørensen, Louise S., Velicogna, Isabella, Whitehouse, Pippa L., Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas P., Blazquez, Alejandro, Colgan, William, Engdahl, Marcus E., Fettweis, Xavier, Forsberg, Rene, Gallée, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian C., Harig, Christopher, Helm, Veit, Khan, Shfaqat Abbas, Kittel, Christoph, Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit S., Liang, Chia Chun, Loomis, Bryant D., McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian H., Mottram, Ruth, Mouginot, Jeremie, Nilsson, Johan, Noël, Brice, Pattle, Mark E., Peltier, William R., Pie, Nadege, Roca, Mònica, Sasgen, Ingo, Save, Himanshu V., Seo, Ki Weon, Scheuchl, Bernd, Schrama, Ernst J.O., Schröder, Ludwig, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler C., Vishwakarma, Bramha Dutt, Van Wessem, Jan Melchior, Wiese, David, Van Der Wal, Wouter, Wouters, Bert, Sub Dynamics Meteorology, Structural geology and EM, Marine and Atmospheric Research, Otosaka, Inès N., Shepherd, Andrew, Ivins, Erik R., Schlegel, Nicole Jeanne, Amory, Charles, Van Den Broeke, Michiel R., Horwath, Martin, Joughin, Ian, King, Michalea D., Krinner, Gerhard, Nowicki, Sophie, Payne, Anthony J., Rignot, Eric, Scambos, Ted, Simon, Karen M., Smith, Benjamin E., Sørensen, Louise S., Velicogna, Isabella, Whitehouse, Pippa L., Geruo, A., Agosta, Cécile, Ahlstrøm, Andreas P., Blazquez, Alejandro, Colgan, William, Engdahl, Marcus E., Fettweis, Xavier, Forsberg, Rene, Gallée, Hubert, Gardner, Alex, Gilbert, Lin, Gourmelen, Noel, Groh, Andreas, Gunter, Brian C., Harig, Christopher, Helm, Veit, Khan, Shfaqat Abbas, Kittel, Christoph, Konrad, Hannes, Langen, Peter L., Lecavalier, Benoit S., Liang, Chia Chun, Loomis, Bryant D., McMillan, Malcolm, Melini, Daniele, Mernild, Sebastian H., Mottram, Ruth, Mouginot, Jeremie, Nilsson, Johan, Noël, Brice, Pattle, Mark E., Peltier, William R., Pie, Nadege, Roca, Mònica, Sasgen, Ingo, Save, Himanshu V., Seo, Ki Weon, Scheuchl, Bernd, Schrama, Ernst J.O., Schröder, Ludwig, Simonsen, Sebastian B., Slater, Thomas, Spada, Giorgio, Sutterley, Tyler C., Vishwakarma, Bramha Dutt, Van Wessem, Jan Melchior, Wiese, David, Van Der Wal, Wouter, and Wouters, Bert

Published
2023

36. Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020

Author

Otosaka, I.N. (author), Shepherd, Andrew (author), Ivins, Erik R. (author), Schlegel, Nicole-Jeanne (author), Amory, Charles (author), Simon, K.M. (author), Schrama, Ernst (author), van der Wal, W. (author), Wouters, B. (author), Otosaka, I.N. (author), Shepherd, Andrew (author), Ivins, Erik R. (author), Schlegel, Nicole-Jeanne (author), Amory, Charles (author), Simon, K.M. (author), Schrama, Ernst (author), van der Wal, W. (author), and Wouters, B. (author)

Abstract

Ice losses from the Greenland and Antarctic ice sheets have accelerated since the 1990s, accounting for a significant increase in the global mean sea level. Here, we present a new 29-year record of ice sheet mass balance from 1992 to 2020 from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE). We compare and combine 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field. Between 1992 and 2020, the ice sheets contributed 21.0±1.9g€¯mm to global mean sea level, with the rate of mass loss rising from 105g€¯Gtg€¯yr-1 between 1992 and 1996 to 372g€¯Gtg€¯yr-1 between 2016 and 2020. In Greenland, the rate of mass loss is 169±9g€¯Gtg€¯yr-1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86g€¯Gtg€¯yr-1 in 2017 to 444g€¯Gtg€¯yr-1 in 2019 due to large variability in surface mass balance. In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9g€¯Gtg€¯yr-1) and, to a lesser extent, from the Antarctic Peninsula (13±5g€¯Gtg€¯yr-1). East Antarctica remains close to a state of balance, with a small gain of 3±15g€¯Gtg€¯yr-1, but is the most uncertain component of Antarctica's mass balance. The dataset is publicly available at 10.5285/77B64C55-7166-4A06-9DEF-2E400398E452 (IMBIE Team, 2021)., Physical and Space Geodesy, Astrodynamics & Space Missions

Published
2023
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41. initMIP-Antarctica: an Ice Sheet Model Initialization Experiment of ISMIP6

Author

Seroussi, Helene, Nowicki, Sophie, Simon, Erika, Abe-Ouchi, Ayako, Albrecht, Torsten, Brondex, Julien, Cornford, Stephen, Dumas, Christophe, Gillet-Chaulet, Fabien, Goelzer, Heiko, Golledge, Nicholas R, Gregory, Jonathan M, Greve, Ralf, Hoffman, Matthew J, Humbert, Angelika, Huybrechts, Philippe, Kleiner, Thomas, Larour, Eric, Leguy, Gunter, Lipscomb, William H, Lowry, Daniel, Mengel, Matthias, Morlighem, Mathieu, Pattyn, Frank, Payne, Anthony J, Pollard, David, Price, Stephen F, Quiquet, Aurélien, Reerink, Thomas J, Reese, Ronja, Rodehacke, Christian B, Schlegel, Nicole-Jeanne, Shepherd, Andrew, Sun, Sainan, Sutter, Johannes, Breedam, Jonas Van, Wal, Roderik S. W. van de, Winkelmann, Ricarda, and Zhang, Tong

Subjects
Geosciences (General)
Abstract

Ice sheet numerical modeling is an important tool to estimate the dynamic contribution of the Antarctic ice sheet to sea level rise over the coming centuries. The influence of initial conditions on ice sheet model simulations, however, is still unclear. To better understand this influence, an initial state intercomparison exercise (initMIP) has been developed to compare, evaluate, and improve initialization procedures and estimate their impact on century-scale simulations. initMIP is the first set of experiments of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), which is the primary Coupled Model Intercomparison Project Phase 6 (CMIP6) activity focusing on the Greenland and Antarctic ice sheets. Following initMIP-Greenland, initMIP-Antarctica has been designed to explore uncertainties associated with model initialization and spin-up and to evaluate the impact of changes in external forcings. Starting from the state of the Antarctic ice sheet at the end of the initialization procedure, three forward experiments are each run for 100 years: a control run, a run with a surface mass balance anomaly, and a run with a basal melting anomaly beneath floating ice. This study presents the results of initMIP-Antarctica from 25 simulations performed by 16 international modeling groups. The submitted results use different initial conditions and initialization methods, as well as ice flow model parameters and reference external forcings. We find a good agreement among model responses to the surface mass balance anomaly but large variations in responses to the basal melting anomaly. These variations can be attributed to differences in the extent of ice shelves and their upstream tributaries, the numerical treatment of grounding line, and the initial ocean conditions applied, suggesting that ongoing efforts to better represent ice shelves in continental-scale models should continue.

Published
2019
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