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2. Two independent methods for mapping the grounding line of an outlet glacier - An example from the Astrolabe Glacier, Terre Adélie, Antarctica

Author

Le Meur, E, Sacchettini, M, Garambois, S, Berthier, E, Drouet, AS, Durand, G, Young, D, Greenbaum, JS, Holt, JW, Blankenship, DD, Rignot, E, Mouginot, J, Gim, Y, Kirchner, D, De Fleurian, B, Gagliardini, O, and Gillet-Chaulet, F

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

The grounding line is a key element of coastal outlet glaciers, acting on their dynamics. Accurately knowing its position is fundamental for both modelling the glacier dynamics and establishing a benchmark for later change detection. Here we map the grounding line of the Astrolabe Glacier in East Antarctica (66°41' S, 140°05' E), using both hydrostatic and tidal methods. The first method is based on new surface and ice thickness data from which the line of buoyant floatation is found. The second method uses kinematic GPS measurements of the tidal response of the ice surface. By detecting the transitions where the ice starts to move vertically in response to the tidal forcing we determine control points for the grounding line position along GPS profiles. Employing a two-dimensional elastic plate model, we compute the rigid short-term behaviour of the ice plate and estimate the correction required to compare the kinematic GPS control points with the previously determined line of floatation. These two approaches show consistency and lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates from the lines obtained so far from satellite imagery. © Author(s) 2014. CC Attribution 3.0 License.

Published
2014

5. OZCAR: The French Network of Critical Zone Observatories

Author

Gaillardet, J., Braud, I., Hankard, F., Anquetin, S., Bour, O., Dorfliger, N., de Dreuzy, J. R., Galle, Sylvie, Galy, C., Gogo, S., Gourcy, L., Habets, F., Laggoun, F., Longuevergne, L., Le Borgne, T., Naaim-Bouvet, F., Nord, G., Simonneaux, Vincent, Six, D., Tallec, T., Valentin, Christian, Abril, G., Allemand, P., Arenes, A., Arfib, B., Arnaud, L., Arnaud, N., Arnaud, P., Audry, S., Comte, V. B., Batiot, C., Battais, A., Bellot, H., Bernard, E., Bertrand, C., Bessiere, H., Binet, S., Bodin, J., Bodin, X., Boithias, Laurie, Bouchez, J., Boudevillain, B., Moussa, I. B., Branger, F., Braun, Jean-Jacques, Brunet, P., Caceres, B., Calmels, D., Cappelaere, Bernard, Celle-Jeanton, H., Chabaux, F., Chalikakis, K., Champollion, C., Copard, Y., Cotel, C., Davy, P., Deline, P., Delrieu, G., Demarty, Jérome, Dessert, C., Dumont, M., Emblanch, C., Ezzahar, J., Esteves, Michel, Favier, V., Faucheux, M., Filizola, N., Flammarion, P., Floury, P., Fovet, O., Fournier, M., Francez, A. J., Gandois, L., Gascuel, C., Gayer, E., Genthon, C., Gerard, M. F., David, Gilbert, Gouttevin, I., Grippa, M., Gruau, G., Jardani, A., Jeanneau, L., Join, J. L., Jourde, H., Karbou, F., Labat, D., Lagadeuc, Y., Lajeunesse, E., Lastennet, R., Lavado, W., Lawin, E., Lebel, Thierry, Le Bouteiller, C., Legout, C., Lejeune, Y., Le Meur, E., Le Moigne, N., Lions, J., Lucas, A., Malet, J. P., Marais-Sicre, C., Marechal, J. C., Marlin, C., Martin, P., Martins, J., Martinez, Jean-Michel, Massei, N., Mauclerc, A., Mazzilli, N., Molenat, J., Moreira Turcq, Patricia, Mougin, E., Morin, S., Ngoupayou, J. N., Panthou, G., Peugeot, Christophe, Picard, G., Pierret, M. C., Porel, G., Probst, A., Probst, J. L., Rabatel, A., Raclot, Damien, Ravanel, L., Rejiba, F., Rene, P., Ribolzi, Olivier, Riotte, Jean, Riviere, A., Robain, Henri, Ruiz, Laurent, Sanchez-Perez, J. M., Santini, William, Sauvage, S., Schoeneich, P., Seidel, J. L., Sekhar, M., Sengtaheuanghoung, O., Silvera, Norbert, Steinmann, M., Soruco, A., Tallec, G., Thibert, E., Lao, D. V., Vincent, Christine, Viville, D., Wagnon, Patrick, and Zitouna, R.

Subjects
lcsh:GE1-350, lcsh:Geology, lcsh:QE1-996.5, lcsh:Environmental sciences
Abstract

The French critical zone initiative, called OZCAR (Observatoires de la Zone Critique–Application et Recherche or Critical Zone Observatories–Application and Research) is a National Research Infrastructure (RI). OZCAR-RI is a network of instrumented sites, bringing together 21 pre-existing research observatories monitoring different compartments of the zone situated between “the rock and the sky,” the Earth’s skin or critical zone (CZ), over the long term. These observatories are regionally based and have specific initial scientific questions, monitoring strategies, databases, and modeling activities. The diversity of OZCAR-RI observatories and sites is well representative of the heterogeneity of the CZ and of the scientific communities studying it. Despite this diversity, all OZCAR-RI sites share a main overarching mandate, which is to monitor, understand, and predict (“earthcast”) the fluxes of water and matter of the Earth’s near surface and how they will change in response to the “new climatic regime.” The vision for OZCAR strategic development aims at designing an open infrastructure, building a national CZ community able to share a systemic representation of the CZ , and educating a new generation of scientists more apt to tackle the wicked problem of the Anthropocene. OZCAR articulates around: (i) a set of common scientific questions and cross-cutting scientific activities using the wealth of OZCAR-RI observatories, (ii) an ambitious instrumental development program, and (iii) a better interaction between data and models to integrate the different time and spatial scales. Internationally, OZCAR-RI aims at strengthening the CZ community by providing a model of organization for pre-existing observatories and by offering CZ instrumented sites. OZCAR is one of two French mirrors of the European Strategy Forum on Research Infrastructure (eLTER-ESFRI) project.

Published
2018

6. Retrieval of Snow Properties from the Sentinel-3 Ocean and Land Colour Instrument

Author

Kokhanovsky, A. A., Lamare, Maxim, Danne, Olaf, Brockmann, Carsten, Dumont, Marie, Picard, Gishlain, Arnaud, Laurent, Favier, Vincent, Jourdain, Bruno, Le Meur, E., Di Mauro, Biagio, Aoki, Teruo, Niwano, Masashi, Rozanov, Vladimir, Korkin, Sergey, Kipfstuhl, S., Freitag, Johannes, Hörhold, Maria, Zuhr, Alexandra, Vladimirova, Diana O., Faber, A. K., Steen-Larsen, Hans Christian, Wahl, Sonja, Andersen, Jonas K., Vandecrux, B., van As, Dirk, Mankoff, Kenneth D., Kern, Michael, Zege, E., Box, J. E., Kokhanovsky, A. A., Lamare, Maxim, Danne, Olaf, Brockmann, Carsten, Dumont, Marie, Picard, Gishlain, Arnaud, Laurent, Favier, Vincent, Jourdain, Bruno, Le Meur, E., Di Mauro, Biagio, Aoki, Teruo, Niwano, Masashi, Rozanov, Vladimir, Korkin, Sergey, Kipfstuhl, S., Freitag, Johannes, Hörhold, Maria, Zuhr, Alexandra, Vladimirova, Diana O., Faber, A. K., Steen-Larsen, Hans Christian, Wahl, Sonja, Andersen, Jonas K., Vandecrux, B., van As, Dirk, Mankoff, Kenneth D., Kern, Michael, Zege, E., and Box, J. E.

Abstract

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400–1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies—especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.

Published
2019

8. Comment coule ce fleuve?

Author

Vincent, C., Six, D., Berthier, E., Le Meur, E., Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), CHYC, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Cryosphère satelittaire (CRYO), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Nussbaumer Samuel, Deline Philippe, Vincent Christian & Zumbühl Hein, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Published
2012

9. Impact of bedrock description on modeling ice sheet dynamics

Author

Durand, Geoffroy, Gagliardini, O., Favier, L., Zwinger, T., Le Meur, E., EDGe, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), EDGE, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)-Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Scientific Computing Ltd (CSC), European Project: 226375,EC:FP7:ENV,FP7-ENV-2008-1,ICE2SEA(2009), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF)

Subjects
DEM, bedrock, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, ice sheet
Abstract

International audience; Recent glaciological surveys have revealed a significant increase of ice discharge from polar ice caps into the ocean. In parallel, ice flow models have been greatly improved to better reproduce current changes and forecast the future behavior of ice sheets. For these models, surface topography and bedrock elevation are crucial input parameters that largely control the dynamics and the ensuing overall mass balance of the ice sheet. For obvious reasons of inaccessibility, only sparse and uneven bedrock elevation data is available. This raw data is processed to produce Digital Elevation Models (DEMs) on a regular 5 km grid. These DEMs are used to constrain the basal boundary conditions of all ice sheet models. Here, by using a full‐Stokes finite element code, we examine the sensitivity of an ice flow model to the accuracy of the bedrock description. In the context of short‐term ice sheet forecast, we show that in coastal regions, the bedrock elevation should be known at a resolution of the order of one kilometer. Conversely, a crude description of the bedrock in the interior of the continent does not affect modeling of the ice outflow into the ocean. These findings clearly indicate that coastal regions should be prioritized during future geophysical surveys. They also indicate that a paradigm shift is required to change the current design of DEMs describing the bedrock below the ice sheets: they must give users the opportunity to incorporate high‐resolution bedrock elevation data in regions of interest.

Published
2011
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10. Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

Author

Touzeau, A., primary, Landais, A., additional, Stenni, B., additional, Uemura, R., additional, Fukui, K., additional, Fujita, S., additional, Guilbaud, S., additional, Ekaykin, A., additional, Casado, M., additional, Barkan, E., additional, Luz, B., additional, Magand, O., additional, Teste, G., additional, Le Meur, E., additional, Baroni, M., additional, Savarino, J., additional, Bourgeois, I., additional, and Risi, C., additional

Published
2015
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11. Supplementary material to "Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters"

Author

Touzeau, A., primary, Landais, A., additional, Stenni, B., additional, Uemura, R., additional, Fukui, K., additional, Fujita, S., additional, Guilbaud, S., additional, Ekaykin, A., additional, Casado, M., additional, Barkan, E., additional, Luz, B., additional, Magand, O., additional, Teste, G., additional, Le Meur, E., additional, Baroni, M., additional, Savarino, J., additional, Bourgeois, I., additional, and Risi, C., additional

Published
2015
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12. Coupling of ice-shelf melting and buttressing is a key process in ice-sheets dynamics

Author

Gagliardini, O., Durand, Geoffroy, Zwinger, T., Hindmarsh, R. C. A., Le Meur, E., Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Scientific Computing Ltd (CSC), CLIPS, EDGE, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), ANR-06-VULN-0016,DACOTA,Dynamique des glaciers côtiers et rôle sur le bilan de masse global de l'Antarctique zone atelier du glacier de l'Astrolabe, Terre Adélie(2006), European Project: 226375,EC:FP7:ENV,FP7-ENV-2008-1,ICE2SEA(2009), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), ANR‐06‐VULN‐016‐01,ANR‐06‐VULN‐016‐01, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG)

Subjects
Meteorology and Climatology, Glaciology, Cryosphere: Ice shelves, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Cryosphere: Modeling (1952), Cryosphere: Dynamics
Abstract

Increase in ice-shelf melting is generally presumed to have triggered recent coastal ice-sheet thinning. Using a full-Stokes finite element model which includes a proper description of the grounding line dynamics, we investigate the impact of melting below ice shelves. We argue that the influence of ice-shelf melting on the ice-sheet dynamics induces a complex response, and the first naive view that melting inevitably leads to loss of grounded ice is erroneous. We demonstrate that melting acts directly on the magnitude of the buttressing force by modifying both the area experiencing lateral resistance and the ice-shelf velocity, indicating that the decrease of back stress imposed by the ice-shelf is the prevailing cause of inland dynamical thinning. We further show that feedback from melting and buttressing forces can lead to nontrivial results, as an increase in the average melt rate may lead to inland ice thickening and grounding line advance. Citation: Gagliardini, O., G. Durand, T. Zwinger, R. C. A. Hindmarsh, and E. Le Meur (2010), Coupling of ice-shelf melting and buttressing is a key process in ice-sheets dynamics, Geophys. Res. Lett., 37, L14501, doi:10.1029/2010GL043334.

Published
2010
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13. Nouvelle analyse de l'origine de la catastrophe de Tête Rousse

Author

Vincent, C., Garambois, S., Thibert, Emmanuel, Lefèbvre, Eléonore, Le Meur, E., Centre National de la Recherche Scientifique (CNRS), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Irstea Publications, Migration

Subjects
[SDE] Environmental Sciences, OUTBURST FLOOD, 12TH JULY 1892, SAINT GERVAIS LES BAINS, TETE ROUSSE GLACIER, [SDE]Environmental Sciences
Abstract

National audience; On 12th July 1892, a sudden drainage of an internal water pocket from the Tete Rousse glacier caused a large outburst flood, destroying a large part of Saint Gervais village and killing 175 people. Many measurements were carried out at the end of the 19th Century in order to understand the origin of this disaster. The origin of this water pocket remains unclear. In 2007, new extensive measurements relative to the thickness of this glacier, ice temperature, and surface mass balance have been performed. These new dataset with the past measurements have been analysed to give new insights into the origin of this outburst flood.

Published
2009

14. Analysis of the outburst flood from glacier de Tête Rousse in 1892 (Mont Blanc area)

Author

Vincent, C., Garambois, S., Le Meur, E., Thibert, Emmanuel, Centre National de la Recherche Scientifique (CNRS), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Irstea Publications, Migration

Subjects
[SDE] Environmental Sciences, OUTBURST FLOOD, 12TH JULY 1892, SAINT GERVAIS LES BAINS, TETE ROUSSE GLACIER, MONT BLANC, [SDE]Environmental Sciences
Abstract

International audience; On 12th July 1892, a sudden drainage of an internal water pocket from the Tete Rousse glacier caused a large outburst flood, destroying a large part of Saint Gervais village and killing 175 people. Many measurements were carried out at the end of the 19th Century in order to understand the origin of this disaster. The origin of this water pocket remains unclear. In 2007, new extensive measurements relative to the thickness of this glacier, ice temperature, and surface mass balance have been performed. These new dataset with the past measurements have been analysed to give new insights into the origin of this outburst flood.

Published
2009

15. The Prader-Willi syndrome murine imprinting center is not involved in the spatio-temporal transcriptional regulation of the Necdin gene

Author

Watrin, F., Le Meur, E., Roeckel, N., Ripoche, M. A., Dandolo, L., Muscatelli, F., Institut de Biologie du Développement de Marseille (IBDM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Département de génétique médicale [Hôpital de la Timone - APHM], Institut National de la Santé et de la Recherche Médicale (INSERM)- Hôpital de la Timone [CHU - APHM] (TIMONE)-Assistance Publique - Hôpitaux de Marseille (APHM)-Aix Marseille Université (AMU), Institut Cochin (IC UM3 (UMR 8104 / U1016)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM), Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)- Hôpital de la Timone [CHU - APHM] (TIMONE)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Biologie du Développement de Marseille ( IBDM ), Aix Marseille Université ( AMU ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ), Aix Marseille Université ( AMU ) -Assistance Publique - Hôpitaux de Marseille ( APHM ) - Hôpital de la Timone [CHU - APHM] ( TIMONE ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ), Institut Cochin ( UM3 (UMR 8104 / U1016) ), Université Paris Descartes - Paris 5 ( UPD5 ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ), Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), and CONTENSIN, Magali

Subjects
Retroelements, Transcription, Genetic, lcsh:QH426-470, Molecular Sequence Data, Mice, Transgenic, Nerve Tissue Proteins, Genomic Imprinting, Mice, Snurf-Snrpn gene, Antigens, Neoplasm, RNA, Small Nuclear, Prader-Willi syndrome (PWS), [SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN], Animals, Humans, In Situ Hybridization, nervous system, Gene Expression Regulation, Developmental, Nuclear Proteins, Proteins, Embryo, Mammalian, Mice, Inbred C57BL, lcsh:Genetics, [ SDV.BBM.GTP ] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN], [SDV.BBM.GTP] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN], Prader-Willi Syndrome, Research Article
Abstract

Background The human Prader-Willi syndrome (PWS) domain and its mouse orthologue include a cluster of paternally expressed genes which imprinted expression is co-ordinately regulated by an imprinting center (IC) closely associated to the Snurf-Snrpn gene. Besides their co-regulated imprinted expression, two observations suggest that the spatio-temporal expression of these genes could also be co-regulated. First, the PWS genes have all been reported to be expressed in the mouse nervous system. Second, Snurf-Snrpn and its associated IC are the most ancient elements of the domain which later acquired additional functional genes by retrotransposition. Although located at least 1.5 megabases from the IC, these retroposons acquired the same imprinted regulation as Snurf-Snrpn. In this study, we ask whether the IC, in addition to its function in imprinting, could also be involved in the spatio-temporal regulation of genes in the PWS domain. Results We compared the expression pattern of Snurf-Snrpn and C/D-box small nucleolar RNAs (snoRNAs) MBII-85 and MBII-52 to the expression pattern of the two evolutionary related retroposons Ndn and Magel2, in the developing mouse embryo. We show that these genes have highly similar expression patterns in the central nervous system, suggesting that they share a common central nervous system-specific regulatory element. Among these genes, Ndn and Magel2 display the most similar expression patterns. Using transgenic mice containing the Ndn and Magel2 genes, we show that the transgenic Ndn gene whereas not imprinted is correctly expressed. Search for DNase I hypersensitive sites in the Ndn-Magel2 genomic region and comparative genomic analyses were performed in order to identify potential transcriptional cis-regulatory elements. Conclusions These results strongly suggest that paternally expressed genes of the PWS domain share a common central nervous system-specific regulatory element. We proposed that this regulatory element could co-localize with the IC. However, we demonstrate that the IC, if required for imprinted regulation, is not involved in the spatio-temporal regulation of distantly located retrotransposed genes such as the Ndn gene in the PWS domain.

Published
2005
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19. Present-day uplift patterns over Greenland from a coupled ice-sheet/visco-elastic bedrock model

Author

Le Meur, E. and Huybrechts, Philippe

Abstract

We present results from a fully coupled ice/ bedrock model calculation of the Greenland ice sheet and the underlying Earth during the last two glacial cycles.The method treats the mutual interaction between the ice and the bedrock and yields the main glacial-isostatic characteristics of the ice-sheet evolution and thebedrock adjustment since the Last Glacial Maximum. By taking advantage of the splitting of the present-day rate of bed uplift into a viscous and an elasticcomponent, these results allow one to distinguish between the bedrock response to the past and present ice sheet evolution, respectively.

Published
1998

20. Two independent methods for mapping the grounding line of an outlet glacier – example from the Astrolabe Glacier, Terre Adélie, Antarctica

Author

Le Meur, E., primary, Sacchettini, M., additional, Garambois, S., additional, Berthier, E., additional, Drouet, A. S., additional, Durand, G., additional, Young, D., additional, Greenbaum, J. S., additional, Blankenship, D. D., additional, Holt, J. W., additional, Rignot, E., additional, Mouginot, J., additional, Gim, Y., additional, Kirchner, D., additional, de Fleurian, B., additional, Gagliardini, O., additional, and Gillet-Chaulet, F., additional

Published
2013
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24. A comparison of different ways of dealing with isostasy: examples from modeling the Antarctic ice sheet during the last glacial cycle

Author

Le Meur, E. and Huybrechts, Philippe

Abstract

The bedrock isostatic response exerts a strong control on ice sheet dynamics and is therefore always taken into account in ice sheet models. This paperreviews the various methods normally used in the ice-sheet modeling community to deal with the bedrock response and compares these with a moresophisticated full Earth model. Each of these bedrock treatments, five in total, are coupled with a three-dimensional thermomechanical ice sheet model underthe same forcing conditions to simulate the Antarctic ice sheet during the last glacial cycle. The outputs of the simulations are compared on the basis of thetime-dependent behavior for the total ice volume and the mean bedrock elevation during the cycle, and of the present rate of uplift over Antarctica. Thiscomparison confirms the necessity of accounting for the elastic bending of the lithosphere in order to yield realistic bedrock patterns. It furthermoredemonstrates the deficiencies inherent to the diffusion equation in modeling the complex deformation within the mantle. Nevertheless, when characteristicparameters are varied within their range of uncertainty, differences within one single method are often of the same order as those between the variousmethods. This overview finally tries to point out the main advantages and drawbacks of each of these methods and to determine which one is mostappropriate depending on the specific modeling requirements.

Published
1996

31. Effects of a viscoelastic lithosphere on the isostatic bedrock response

Author

Le Meur, E. and Le Meur, E.

Abstract

The lithosphere responds to loading by elastic flexure which is followed by viscous relaxation, the amount of which depends on the stress duration. This study compares results of an Earth model in which the lithosphere is modelled as a purely elastic layer and as a more general viscoelastic solid overlain by a rigid crust. It shows the emergence of a noticeable difference in the short wavelength (1×102–5×102 km) component of the bedrock deformation after loading durations of the order of 105–106 yr assuming a lower lithosphere viscosity of the order of 1023–1024 Pa.s. In particular, for the long-term loading hypothesised to be imposed by the East Antarctic ice sheet, we find that aviscoelasticlithosphere yields a more local deformation pattern to which ice sheet dynamics are highly sensitive. It confirms that modelling of the Antarctic long-term evolution would benefit from a fully coupled ice/bedrock approach in which the lithosphere would be represented by aviscoelastic solid.

Published
2001

32. Dynamical processes involved in the retreat of marine ice sheets

Author

Hindmarsh, Richard C.A., Le Meur, E., Hindmarsh, Richard C.A., and Le Meur, E.

Abstract

Marine ice sheets with mechanics described by the shallow-ice approximation by definition do not couple mechanically with the shelf. Such ice sheets are known to have neutral equilibria. We consider the implications of this for their dynamics and in particular for mechanisms which promote marine ice-sheet retreat. The removal of ice-shelf buttressing leading to enhanced flow in grounded ice is discounted as a significant influence on mechanical grounds. Sea-level rise leading to reduced effective pressures under ice streams is shown to be a feasible mechanism for producing postglacial West Antarctic ice-sheet retreat but is inconsistent with borehole evidence. Warming thins the ice sheet by reducing the average viscosity but does not lead to grounding-line retreat. Internal oscillations either specified or generated via a MacAyeal-Payne thermal mechanism promote migration. This is a noise-induced drift phenomenon stemming from the neutral equilibrium property of marine ice sheets. This migration occurs at quite slow rates, but these are sufficiently large to have possibly played a role in the dynamics of the West Antarctic ice sheet after the glacial maximum. Numerical experiments suggest that it is generally true that while significant changes in thickness can be caused by spatially uniform changes, spatial variability coupled with dynamical variability is needed to cause margin movement.

Published
2001

33. A model computation of the temporal changes of surface gravity and geoidal signal induced by the evolving Greenland ice sheet

Author

Le Meur, E., Huybrechts, Philippe, Le Meur, E., and Huybrechts, Philippe

Abstract

This paper deals with present-day gravity changes inresponse to the evolving Greenland ice sheet. We present a detailedcomputation from a three-dimensionalthermomechanical ice-sheet model which is interactivelycoupled with a self-gravitating spherical visco-elastic bedrock model.The coupled model is run over the last two glacial cycles to yield theloading evolution over time. Based on both the ice-sheet's long-term historyand its modern evolution averaged over thelast 200 years, results are presented of the absolute gravity trend that wouldarise from a ground surveyand of the corresponding geoid rate of change a satellite would see from space.The main results yield ground absolute gravity trends of the order of +/-1 microgal/yr over the ice-free areasand total geoid changes in the range between -0.1 and +0.3 mm/yr.These estimates could help to design futuremeasurement campaigns by revealing areas of strongsignal and/or specific patterns, although there are uncertainties associated withthe parameters adopted for the Earth's rheology and aspects of the ice sheetmodel.Given the instrumental accuracy ofa particular surveying method, these theoretical trends could also be useful toassess the required duration of a measurement campaign. According to our results,the present-day gravitational signal is dominated by the responseto past loading changes rather than current mass changes of the Greenland icesheet.We finally discuss the potential of inferring thepresent-day evolution of the Greenlandice sheet from the geoid rate of change measured by the future geodeticGRACE mission. We find that despite the anticipatedhigh quality data from satellites, such a methodis compromised by the uncertainties in the Earth model,the dominance of isostatic recovery on the current bedrock signal,and other inaccuracies inherent to the method itself.

Published
2001

34. Coupled marine-ice-sheet/Earth dynamics using a dynamically consistent ice-sheet model and a self-gravitating viscous Earth model

Author

Le Meur, E., Hindmarsh, Richard C.A., Le Meur, E., and Hindmarsh, Richard C.A.

Abstract

We use a self-gravitating viscoelastic model of the Earth and a dynamically consistent marine ice-sheet model to study the relationships between marine ice-sheet dynamics, relative sea level, basal topography and bedrock dynamics. Our main conclusion is that sea-level change and lithospheric coupling are likely to have played limited roles in the postglacial retreat of marine ice sheets. The postglacial rise in sea level would only have caused at the most around 100 km of grounding-line retreat for an ice sheet of similar dimensions to the West Antarctic ice sheet, compared with the several hundred km of retreat which has occurred in the Ross Sea. There is no evidence that reverse slopes lead to instability. Incorporating coupling with lithospheric dynamics does not produce markedly different effects. The implication of these studies is that marine ice-sheet retreat is the result of physical mechanisms other than lithospheric coupling and sea-level rise.

Published
2001

36. A comparison of two spectral approaches for computing the Earth response to surface loads

Author

Le Meur, E., Hindmarsh, R.C.A., Le Meur, E., and Hindmarsh, R.C.A.

Abstract

When predicting the deformation of the Earth under surface loads, most models follow the same methodology, consisting of producing a unit response that is then con-volved with the appropriate surface forcing. These models take into account the whole Earth, and are generally spherical, computing a unit response in terms of its spherical harmonic representation through the use of load Love numbers. From these Love numbers, the spatial pattern of the bedrock response to any particular scenario can be obtained. Two different methods are discussed here. The first, which is related to the convolution in the classical sense, appears to be very sensitive to the total number of degrees used when summing these Love numbers in the harmonic series in order to obtain the corresponding Green’s function. We will see from the spectral properties of these Love numbers how to compute these series correctly and how consequently to eliminate in practice the sensitivity to the number of degrees (Gibbs Phenomena). The second method relies on a preliminary harmonic decomposition of the load, which reduces the convolution to a simple product within Fourier space. The convergence properties of the resulting Fourier series make this approach less sensitive to any harmonic cut-off. However, this method can be more or less computationally expensive depending on the loading characteristics. This paper describes these two methods, how to eliminate Gibbs phenomena in the Green’s function method, and shows how the load characteristics as well as the available computational resources can be determining factors in selecting one approach.

Published
2000

41. Predicted present-day evolution patterns of ice thickness and bedrock elevation over Greenland and Antarctica

Author

Huybrechts, Philippe, Le Meur, E., Huybrechts, Philippe, and Le Meur, E.

Abstract

The paper presents a discussion of evolution patterns of present-day changes of ice thickness, surface elevation, and bedrock elevation over the Greenlandand Antarctic continents. These patterns were obtained from calculations with dynamic 3-D thermomechanic ice sheet models which were coupled to aself-gravitating spherical visco-elastic Earth model. The experiments were initialized with simulations over the last two glacial cycles and subsequentlyanalyzed over the last 200 years to obtain the present evolution. The calculations brought to light that the Antarctic ice sheet is still adjusting to the lastglacial-interglacial transition yielding a decreasing ice volume and a rising bedrock elevation of the order of several cm per year. The Greenland ice sheet, onthe other hand, was found to be close to a stationary state with a mean thickness change of only a few mm per year. However, the calculations revealed largespatial differences. Patterns over Greenland are characterized by a small thickening over the ice-sheet interior and a general thinning of the ablation areatogether with a concomitant concentric pattern of rising bedrock elevations around the Greenland margin and a small sinking below central Greenland. InAntarctica, almost all of the changes are concentrated in the West Antarctic ice sheet, which is still retreating at both the Weddell and Ross Sea margins. Overmost of both ice sheets, the surface elevation trend is dominated by ice thickness changes rather than by bedrock elevation changes.

Published
1999

47. Low-frequency radar sounding of ice in East Antarctica and southern Greenland.

Author

MOUGINOT, J., RIGNOT, E., GIM, Y., KIRCHNER, D., and LE MEUR, E.

Subjects
ICE streams, RADAR in aeronautics, WAVELENGTHS, ENVIRONMENTAL impact analysis, COMPARATIVE studies
Abstract

We discuss a decameter-wavelength airborne radar sounder, the Warm Ice Sounding Explorer (WISE), that provides ice thickness in areas where radar signal penetration at higher frequencies is expected to be limited. Here we report results for three campaigns conducted in Greenland (2008, 2009, 2010) and two in Antarctica (2009, 2010). Comparisons with higher-frequency radar data indicate an accuracy of ±55m for ice-thickness measurements in Greenland and ±25m in Antarctica. We also estimate ice thickness of the Qassimiut lobe in southwest Greenland, where few ice-thickness measurements have been made, demonstrating that WISE penetrates in strongly scattering environments. [ABSTRACT FROM AUTHOR]

Published
2014
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