Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter
International audience Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea level rise. The basal conditions exert an important control on the ice dynamics and can be propitious to instabilities in the grounding line position. Because the force balance is non-inertial...
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ftinsu:oai:HAL:hal-03031278v1 2024-04-28T08:01:24+00:00 Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter Gillet-Chaulet, Fabien Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ) Université Grenoble Alpes (UGA) 2020 https://hal.science/hal-03031278 https://hal.science/hal-03031278/document https://hal.science/hal-03031278/file/tc-14-811-2020.pdf https://doi.org/10.5194/tc-14-811-2020 en eng HAL CCSD Copernicus info:eu-repo/semantics/altIdentifier/doi/10.5194/tc-14-811-2020 hal-03031278 https://hal.science/hal-03031278 https://hal.science/hal-03031278/document https://hal.science/hal-03031278/file/tc-14-811-2020.pdf doi:10.5194/tc-14-811-2020 info:eu-repo/semantics/OpenAccess ISSN: 1994-0424 EISSN: 1994-0416 The Cryosphere https://hal.science/hal-03031278 The Cryosphere, 2020, 14 (3), pp.811-832. ⟨10.5194/tc-14-811-2020⟩ [SDE]Environmental Sciences info:eu-repo/semantics/article Journal articles 2020 ftinsu https://doi.org/10.5194/tc-14-811-2020 2024-04-05T00:39:09Z International audience Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea level rise. The basal conditions exert an important control on the ice dynamics and can be propitious to instabilities in the grounding line position. Because the force balance is non-inertial, most ice flow models are now equipped with time-independent inverse methods to constrain the basal conditions from observed surface velocities. However, transient simulations starting from this initial state usually suffer from inconsistencies and are not able to reproduce observed trends. Here, using a synthetic flow line experiment, we assess the performance of an ensemble Kalman filter for the assimilation of transient observations of surface elevation and velocities in a marine ice sheet model. The model solves the shallow shelf equation for the force balance and the continuity equation for ice thickness evolution. The position of the grounding line is determined by the floatation criterion. The filter analysis estimates both the state of the model, represented by the surface elevation, and the basal conditions, with the simultaneous inversion of the basal friction and topography. The idealised experiment reproduces a marine ice sheet that is in the early stage of an unstable retreat. Using observation frequencies and uncertainties consistent with current observing systems, we find that the filter allows the accurate recovery of both the basal friction and topography after few assimilation cycles with relatively small ensemble sizes. In addition it is found that assimilating the surface observations has a positive impact on constraining the evolution of the grounding line during the assimilation window. Using the initialised state to perform century-scale forecast simulations, we show that grounding line retreat rates are in agreement with the reference; however remaining uncertainties in the basal conditions may lead to significant delays in the initiation of the unstable retreat. These results are ... Article in Journal/Newspaper Antarc* Antarctic Ice Sheet The Cryosphere Institut national des sciences de l'Univers: HAL-INSU The Cryosphere 14 3 811 832 |
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Institut national des sciences de l'Univers: HAL-INSU |
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language |
English |
topic |
[SDE]Environmental Sciences |
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[SDE]Environmental Sciences Gillet-Chaulet, Fabien Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
topic_facet |
[SDE]Environmental Sciences |
description |
International audience Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea level rise. The basal conditions exert an important control on the ice dynamics and can be propitious to instabilities in the grounding line position. Because the force balance is non-inertial, most ice flow models are now equipped with time-independent inverse methods to constrain the basal conditions from observed surface velocities. However, transient simulations starting from this initial state usually suffer from inconsistencies and are not able to reproduce observed trends. Here, using a synthetic flow line experiment, we assess the performance of an ensemble Kalman filter for the assimilation of transient observations of surface elevation and velocities in a marine ice sheet model. The model solves the shallow shelf equation for the force balance and the continuity equation for ice thickness evolution. The position of the grounding line is determined by the floatation criterion. The filter analysis estimates both the state of the model, represented by the surface elevation, and the basal conditions, with the simultaneous inversion of the basal friction and topography. The idealised experiment reproduces a marine ice sheet that is in the early stage of an unstable retreat. Using observation frequencies and uncertainties consistent with current observing systems, we find that the filter allows the accurate recovery of both the basal friction and topography after few assimilation cycles with relatively small ensemble sizes. In addition it is found that assimilating the surface observations has a positive impact on constraining the evolution of the grounding line during the assimilation window. Using the initialised state to perform century-scale forecast simulations, we show that grounding line retreat rates are in agreement with the reference; however remaining uncertainties in the basal conditions may lead to significant delays in the initiation of the unstable retreat. These results are ... |
author2 |
Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ) Université Grenoble Alpes (UGA) |
format |
Article in Journal/Newspaper |
author |
Gillet-Chaulet, Fabien |
author_facet |
Gillet-Chaulet, Fabien |
author_sort |
Gillet-Chaulet, Fabien |
title |
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
title_short |
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
title_full |
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
title_fullStr |
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
title_full_unstemmed |
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter |
title_sort |
assimilation of surface observations in a transient marine ice sheet model using an ensemble kalman filter |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal.science/hal-03031278 https://hal.science/hal-03031278/document https://hal.science/hal-03031278/file/tc-14-811-2020.pdf https://doi.org/10.5194/tc-14-811-2020 |
genre |
Antarc* Antarctic Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctic Ice Sheet The Cryosphere |
op_source |
ISSN: 1994-0424 EISSN: 1994-0416 The Cryosphere https://hal.science/hal-03031278 The Cryosphere, 2020, 14 (3), pp.811-832. ⟨10.5194/tc-14-811-2020⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/tc-14-811-2020 hal-03031278 https://hal.science/hal-03031278 https://hal.science/hal-03031278/document https://hal.science/hal-03031278/file/tc-14-811-2020.pdf doi:10.5194/tc-14-811-2020 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/tc-14-811-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
3 |
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811 |
op_container_end_page |
832 |
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1797573150332944384 |