Julie Deshayes

Julie Deshayes
French National Centre for Scientific Research | CNRS · Laboratoire de physique des océans (LPO)

PhD

About

66
Publications
14,232
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3,702
Citations
Citations since 2016
35 Research Items
3035 Citations
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20162017201820192020202120220200400600
20162017201820192020202120220200400600
20162017201820192020202120220200400600

Publications

Publications (66)
Article
Traditional general circulation models, or GCMs—that is, three-dimensional dynamical models with unresolved terms represented in equations with tunable parameters—have been a mainstay of climate research for several decades, and some of the pioneering studies have recently been recognized by a Nobel prize in Physics. Yet, there is considerable deba...
Article
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The trustworthiness of neural networks is often challenged because they lack the ability to express uncertainty and explain their skill. This can be problematic given the increasing use of neural networks in high stakes decision‐making such as in climate change applications. We address both issues by successfully implementing a Bayesian Neural Netw...
Article
Full-text available
The seasonal variability of Agulhas Current properties is not well understood because there have been few data collected during austral winter. Here we analyze 8 repeat hydrographic sections that have been collected across the Agulhas Current at 34°S over the past decade, including the first full‐depth winter surveys of the Agulhas Current, collect...
Preprint
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The objective of this study is to evaluate the potential for History Matching (HM) to tune a climate system with multi-scale dynamics. By considering a toy climate model, namely, the two-scale Lorenz96 model and producing experiments in perfect-model setting, we explore in detail how several built-in choices need to be carefully tested. We also dem...
Article
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The Atlantic Meridional Overturning Circulation (AMOC) is a crucial element of the Earth climate. It is a complex circulation system difficult to monitor and to model. There is considerable debate regarding its evolution over the last century as well as large uncertainty about its fate at the end of this century. We depict here the progress since t...
Article
Full-text available
Greenland ice sheet experienced an intensive melting in the last century, especially in the 1920s and over the last decades. The supplementary input into the ocean could disrupt the freshwater budget of the North Atlantic. Simultaneously, some signs of a recent weakening of the Atlantic Meridional Overturning Circulation (AMOC) have been reported....
Article
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Some of the new generation CMIP6 models are characterised by a strong temperature increase in response to increasing greenhouse gases concentration¹. At first glance, these models seem less consistent with the temperature warming observed over the last decades. Here, we investigate this issue through the prism of low-frequency internal variability...
Article
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The Institut Pierre‐Simon Laplace Climate Modeling Center has produced an ensemble of extended historical simulations using the IPSL‐CM6A‐LR climate model. This ensemble (referred to as IPSL‐EHS) is composed of 32 members over the 1850–2059 period that share the same external forcings but differ in their initial conditions. In this study, we assess...
Article
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Plain Language Summary Evaluating current and future risks for natural and human systems associated with climate change is largely based on numerical simulations performed with models of the climate system, which includes the atmosphere, the land, the ocean, the cryosphere, and the oceanic and terrestrial biosphere. Various steps are involved in th...
Preprint
Full-text available
Greenland ice sheet experienced an intensive melting in the last century, especially in the 1920s and over the last decades. The supplementary input into the ocean could disrupt the freshwater budget of the North Atlantic. Simultaneously, some signs of a recent weakening of the Atlantic Meridional Overturning Circulation (AMOC) have been reported....
Presentation
Full-text available
Ce document synthétise la démarche de réflexion et d'élaboration du vote au sein du LOCEAN visant à réduire l'empreinte carbone de nos activités, de octobre 2018 à septembre 2020.
Article
Full-text available
Ocean biogeochemical models are key tools for both scientific and operational applications. Nevertheless the cost of these models is often expensive because of the large number of biogeochemical tracers. This has motivated the development of multi-grid approaches where ocean dynamics and tracer transport are computed on grids of different spatial r...
Article
Full-text available
We investigate in this paper the sensitivity of the representation of the Denmark Strait overflow produced by a regional z-coordinate configuration of NEMO (version 3.6) to the horizontal and vertical grid resolutions and to various numerical and physical parameters. Three different horizontal resolutions, 1∕12, 1∕36, and 1/60∘, are respectively us...
Article
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Abstract This study presents the global climate model IPSL‐CM6A‐LR developed at Institut Pierre‐Simon Laplace (IPSL) to study natural climate variability and climate response to natural and anthropogenic forcings as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). This article describes the different model components, t...
Poster
Full-text available
Infographie réalisée en Juillet 2020 pour préparer le vote sur le réduction de l'empreinte carbone de septembre.
Article
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To investigate the role of tides in Weddell Sea ocean‐ice shelf melt interactions, and resulting consequences for ocean properties and sea ice interactions, we develop a regional ocean‐sea ice model configuration, with time‐varying ocean boundary and atmospheric forcing, including the deep open ocean (at 2.5–4 km horizontal resolution), the southwe...
Article
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The physical oceanographic environment, water mass characteristics, and distribution in the area adjacent to Larsen C Ice Shelf (LCIS) are investigated using hydrographic data collected during the 2019 Weddell Sea Expedition. The results shed light on the ocean conditions adjacent to a thinning LCIS, on a continental shelf that is a source region f...
Preprint
Full-text available
Abstract. Ocean biogeochemical models are key tools for both scientific and operational applications. Nevertheless the cost of running these models is often expensive because of the large number of biogeochemical tracers. This has motivated the development of multi-grid approaches where ocean dynamics and tracer transport are computed on grids of d...
Preprint
Full-text available
Abstract. We investigate in this paper the sensitivity of the representation of the Denmark Strait overflow produced by a regional z-coordinate configuration of NEMO (version 3.6) to the horizontal and vertical grid resolutions and to various numerical and physical parameters. Three different horizontal resolutions, 1/12°, 1/36° and 1/60°, are used...
Article
Full-text available
Abstract This study introduces CNRM‐ESM2‐1, the Earth system (ES) model of second generation developed by CNRM‐CERFACS for the sixth phase of the Coupled Model Intercomparison Project (CMIP6). CNRM‐ESM2‐1 offers a higher model complexity than the Atmosphere‐Ocean General Circulation Model CNRM‐CM6‐1 by adding interactive ES components such as carbo...
Article
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Abstract This paper describes the main characteristics of CNRM‐CM6‐1, the fully coupled atmosphere‐ocean general circulation model of sixth generation jointly developed by Centre National de Recherches Météorologiques (CNRM) and Cerfacs for the sixth phase of the Coupled Model Intercomparison Project 6 (CMIP6). The paper provides a description of e...
Article
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Preindustrial control simulations with the third Hadley Centre Global Environmental Model, run in the Global Coupled configuration 3.1 of the Met Office Unified Model (HadGEM3‐GC3.1) are presented at two resolutions. These are N216ORCA025, which has a horizontal resolution of 60 km in the atmosphere and 0.25° in the ocean, and N96ORCA1, which has a...
Article
Full-text available
Preindustrial control simulations with the third Hadley Centre Global Environmental Model, run in the Global Coupled configuration 3.1 of the Met Office Unified Model (HadGEM3‐GC3.1) are presented at two resolutions. These are N216ORCA025, which has a horizontal resolution of 60 km in the atmosphere and 0.25° in the ocean, and N96ORCA1, which has a...
Article
Full-text available
Small pelagic fish play a significant role in regulating the foraging activities and population trends of marine top predators in upwelling ecosystems, yet there is little information on oceanographic drivers of fish assemblages at temporal and spatial scales relevant to their predators. The survival of the Endangered African penguin Spheniscus dem...
Article
Correlations between temperature and velocity fluctuations are a significant contribution to the North Atlantic meridional heat transport, especially at the northern boundary of the subtropical gyre. In satellite observations and in a numerical model at 7/8° resolution, a localized pattern of positive eddy heat flux is found northwest of the Gulf S...
Article
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Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat and salt and hence global climate. Quantifying Agulhas leakage is challen...
Article
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The Ocean Model Intercomparison Project (OMIP) is an endorsed project in the Coupled Model Intercomparison Project Phase 6 (CMIP6). OMIP addresses CMIP6 science questions, investigating the origins and consequences of systematic model biases. It does so by providing a framework for evaluating (including assessment of systematic biases), understandi...
Article
Full-text available
The Ocean Model Intercomparison Project (OMIP) aims to provide a framework for evaluating, understanding, and improving the ocean and sea-ice components of global climate and earth system models contributing to the Coupled Model Intercomparison Project Phase 6 (CMIP6). OMIP addresses these aims in two complementary manners: (A) by providing an expe...
Article
Full-text available
Large differences in the Atlantic meridional overturning circulation (AMOC) exhibited between the available ocean models pose problems as to how they can be interpreted for climate policy. A novel Lagrangian methodology has been developed for use with ocean models that enables a decomposition of the AMOC according to its source waters of subduction...
Article
In the mid 1990s, the North Atlantic subpolar gyre has shown a dramatic warming event that has been thoroughly investigated from observations and numerical simulations. Some studies suggest that it was due to an interannual, wind-driven weakening and shrinking of the gyre that facilitated the penetration of warm Atlantic Water, the weakening of the...
Article
Atmospheric weather regimes are a promising alternative to the modes of variability traditionally used to assess the impacts of atmospheric variability on the oceanic circulation in the North Atlantic. Indeed, they preserve the spatial asymmetry of the dominant mode of variability, the North Atlantic Oscillation. Using numerical simulations and tid...
Article
The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air-sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensified. This is opposite to the relationship of freshening caus...
Article
Full-text available
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12 • resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global anal-ysis of the salinity balance in relation to surface water fluxes, without defining a "freshwater anomaly" based on an arbi...
Article
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12° resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global analysis of the salinity balance in relation to surface water fluxes, without defining a "freshwater anomaly" based on an arbitr...
Article
Previous studies have shown that low horizontal resolution (of the order of 1°) ocean models, hence climate models, are not able to adequately represent boundary currents nor mesoscale processes which affect the dynamics and thermohaline circulation of the ocean. While the effect of mesoscale eddies can be parameterized in low resolution models, bo...
Poster
Full-text available
In the mid-90s, the North-Atlantic subpolar gyre has shown a dramatic warming that has been attributed to changes in the large-scale atmospheric variability. This warming has often been attributed to an abrupt change in the North-Atlantic Oscillation, from highly positive in 1995 to highly negative in 1996. However, decadal prediction experiments s...
Article
A new framework is proposed for investigating the atmospheric forcing of North Atlantic Ocean circulation. Instead of using classical modes of variability, such as the North Atlantic Oscillation (NAO) or the east Atlantic pattern, the weather regimes paradigm was used. Using this framework helped avoid problems associated with the assumptions of or...
Article
Full-text available
This study analyses the impact on the oceanic mean state of the evolution of the oceanic component (NEMO) of the climate model developed at Institut Pierre Simon Laplace (IPSL-CM), from the version IPSL-CM4, used for third phase of the Coupled Model Intercomparison Project (CMIP3), to IPSL-CM5A, used for CMIP5. Several modifications have been imple...
Article
Full-text available
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12° resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global analysis of the salinity balance in relation with surface water fluxes, without defining a "freshwater anomaly" based on an arbi...
Article
Subtropical mode waters are characterized by low potential vorticity (PV) and so the mechanisms by which PV is extracted from the ocean by air–sea interaction are of great relevance to our understanding of how mode waters are formed. This study analyzes those mechanisms by comparing the magnitude and spatial patterns of surface PV fluxes of diabati...
Article
All climate models predict a freshening of the North Atlantic at high latitude that may induce an abrupt change of the Atlantic Meridional Overturning Circulation (hereafter AMOC) if it resides in the bistable regime, where both a strong and a weak state coexist. The latter remains uncertain as there is no consensus among observations and ocean rea...
Article
A new version of the general circulation model CNRM-CM has been developed jointly by CNRM-GAME (Centre National de Recherches Météorologiques—Groupe d’études de l’Atmosphère Météorologique) and Cerfacs (Centre Européen de Recherche et de Formation Avancée) in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The p...
Conference Paper
The spatial distribution of salinity in the world ocean is governed by the ocean circulation that transports salt from evaporative subtropical regions to precipitation-dominated regions (at high latitudes and in the tropics). Observations suggest that in a steady state, up to 30. 106 kg/s of salt must be carried by circulation cells with correlated...
Article
Before performing any procedure or initiating early intervention on children in lacteal dentition, it is crucial to closely investigate a few key elements of the cranial base of the child. A first step of diagnostics is needed - the classification of the dysharmony ie its squelettal and/or functional element - before we prescribe a major orthopedic...
Article
A new version of the general circulation model CNRM-CM has been developed jointly by CNRM-GAME (Centre National de Recherches Météorologiques-Groupe d'Etudes de l'AtmosphSre Météorologique) and Cerfacs (Centre Européen de Recherche et de Formation Avancée) in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The p...
Article
Full-text available
Interannual variability of subtropical sea-surface-height (SSH) anomalies, estimated by satellite and tide-gauge data, is investigated in relation to wintertime daily North-Atlantic weather regimes. Sea-level anomalies can be viewed as proxies for the subtropical gyre intensity because of the intrinsic baroclinic structure of the circulation. Our r...
Article
Full-text available
1] The meridional transport of salt in the Atlantic ocean is an important process for climate, controlling the stability of the meridional overturning circulation. The contribution of transient eddies to this transport is quantified in an eddy resolving North Atlantic model at 1/12 resolution (NATL12), and compared with lower resolution North-Atlan...
Article
Full-text available
A new version of the general circulation model CNRM-CM has been developed jointly by CNRM-GAME (Centre National de Recherches Météorologiques—Groupe d’études de l’Atmosphère Météorologique) and Cerfacs (Centre Européen de Recherche et de Formation Avancée) in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The p...
Presentation
Full-text available
The first mode of atmospheric variability in the North-Atlantic is the so-called North-Atlantic Oscillation (NAO), which, for its positive (negative) phase, corresponds to the simultaneous strengthening (weakening) of the Icelandic Low and Azores High. The NAO impact on ocean circulation has been thoroughly studied in literature; however, littlle i...