Ensemble quantification of short-term predictability of the ocean fine-scale dynamics
International audience In this contribution, we investigate the predictability properties of the ocean dynamics using an ensemble of medium range numerical forecasts. This question is particularly relevant for ocean dynamics at small scales (< 30 km), where sub-mesoscale dynamics is responsible f...
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ftinsu:oai:HAL:hal-04549971v1 2024-10-06T13:51:16+00:00 Ensemble quantification of short-term predictability of the ocean fine-scale dynamics Leroux, Stéphanie Brankart, Jean-Michel Albert, Aurélie Molines, Jean-Marc Brodeau, Laurent Le Sommer, Julien Penduff, Thierry Brasseur, Pierre 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP) Université Grenoble Alpes (UGA) Online/Vienna, Austria 2021-04 https://hal.science/hal-04549971 https://doi.org/10.5194/egusphere-egu21-12001 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-12001 EGU General Assembly https://hal.science/hal-04549971 EGU General Assembly, Apr 2021, Online/Vienna, Austria. ⟨10.5194/egusphere-egu21-12001⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/conferenceObject Conference papers 2021 ftinsu https://doi.org/10.5194/egusphere-egu21-12001 2024-09-26T15:02:33Z International audience In this contribution, we investigate the predictability properties of the ocean dynamics using an ensemble of medium range numerical forecasts. This question is particularly relevant for ocean dynamics at small scales (< 30 km), where sub-mesoscale dynamics is responsible for the fast evolution of ocean properties. Relatively little is known about the predictability properties of a high resolution model, and hence about the accuracy and resolution that is needed from the observation system used to generate the initial conditions.A kilometric-scale regional configuration of NEMO for the Western Mediterranean (MEDWEST60, at 1/60º horizontal resolution) has been developed, using boundary conditions from a larger North Atlantic configuration at same resolution (eNATL60). This deterministic model has then been transformed into a probabilistic model by introducing innovative stochastic parameterizations of model uncertainties resulting from unresolved processes. The purpose is here primarily to generate ensembles of model states to initialize predictability experiments. The stochastic parameterization is also applied to assess the possible impact of irreducible model uncertainties on the skill of the forecast. A set of three ensemble experiments (20 members and 2 months ) are performed, one with the deterministic model initiated with perturbed initial conditions, and two with the stochastic model, for two different amplitudes of model uncertainty. In all three experiments, the spread of the ensemble is shown to emerge from the small scales (10 km wavelength) and progressively upscales to the largest structures. After two months, the ensemble variance saturates over most of the spectrum (except in the largest scales), whereas the small scales (< 30 km) are fully decorrelated between the different members. These ensemble simulations are thus appropriate to provide a statistical description of the dependence between initial accuracy and forecast accuracy over the full range of ... Conference Object North Atlantic Institut national des sciences de l'Univers: HAL-INSU |
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Institut national des sciences de l'Univers: HAL-INSU |
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ftinsu |
language |
English |
topic |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
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[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography Leroux, Stéphanie Brankart, Jean-Michel Albert, Aurélie Molines, Jean-Marc Brodeau, Laurent Le Sommer, Julien Penduff, Thierry Brasseur, Pierre Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience In this contribution, we investigate the predictability properties of the ocean dynamics using an ensemble of medium range numerical forecasts. This question is particularly relevant for ocean dynamics at small scales (< 30 km), where sub-mesoscale dynamics is responsible for the fast evolution of ocean properties. Relatively little is known about the predictability properties of a high resolution model, and hence about the accuracy and resolution that is needed from the observation system used to generate the initial conditions.A kilometric-scale regional configuration of NEMO for the Western Mediterranean (MEDWEST60, at 1/60º horizontal resolution) has been developed, using boundary conditions from a larger North Atlantic configuration at same resolution (eNATL60). This deterministic model has then been transformed into a probabilistic model by introducing innovative stochastic parameterizations of model uncertainties resulting from unresolved processes. The purpose is here primarily to generate ensembles of model states to initialize predictability experiments. The stochastic parameterization is also applied to assess the possible impact of irreducible model uncertainties on the skill of the forecast. A set of three ensemble experiments (20 members and 2 months ) are performed, one with the deterministic model initiated with perturbed initial conditions, and two with the stochastic model, for two different amplitudes of model uncertainty. In all three experiments, the spread of the ensemble is shown to emerge from the small scales (10 km wavelength) and progressively upscales to the largest structures. After two months, the ensemble variance saturates over most of the spectrum (except in the largest scales), whereas the small scales (< 30 km) are fully decorrelated between the different members. These ensemble simulations are thus appropriate to provide a statistical description of the dependence between initial accuracy and forecast accuracy over the full range of ... |
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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP) Université Grenoble Alpes (UGA) |
format |
Conference Object |
author |
Leroux, Stéphanie Brankart, Jean-Michel Albert, Aurélie Molines, Jean-Marc Brodeau, Laurent Le Sommer, Julien Penduff, Thierry Brasseur, Pierre |
author_facet |
Leroux, Stéphanie Brankart, Jean-Michel Albert, Aurélie Molines, Jean-Marc Brodeau, Laurent Le Sommer, Julien Penduff, Thierry Brasseur, Pierre |
author_sort |
Leroux, Stéphanie |
title |
Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
title_short |
Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
title_full |
Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
title_fullStr |
Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
title_full_unstemmed |
Ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
title_sort |
ensemble quantification of short-term predictability of the ocean fine-scale dynamics |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-04549971 https://doi.org/10.5194/egusphere-egu21-12001 |
op_coverage |
Online/Vienna, Austria |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
EGU General Assembly https://hal.science/hal-04549971 EGU General Assembly, Apr 2021, Online/Vienna, Austria. ⟨10.5194/egusphere-egu21-12001⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-12001 |
op_doi |
https://doi.org/10.5194/egusphere-egu21-12001 |
_version_ |
1812179477500788736 |