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1. Modulation of the occurrence of heat waves over the Euro-Mediterranean region by the intensity of the Atlantic Multidecadal Variability

Author

Qasmi, Saïd, Sanchez-Gomez, Emilia, Ruprich-Robert, Yohan, Boé, Julien, and Cassou, Christophe

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

The influence of the Atlantic Multidecadal Variability (AMV) and its amplitude on the Euro-Mediterranean summer climate is studied in two climate models, namely CNRM-CM5 and EC-Earth3P. Large ensembles of idealized experiments have been conducted in which North Atlantic sea surface temperatures (SSTs) are relaxed towards different amplitudes of the observed AMV anomalies. In agreement with observations, during a positive phase of the AMV both models simulate an increase (decrease) of temperature and a decrease (increase) of precipitation over the Mediterranean basin (northern half of Europe). An increase in the number of heat wave (HW) days is also found over the continental Mediterranean region. In terms of atmospheric circulation, an anomalous ridge (trough) over the Mediterranean basin (northern Europe) induces a thermodynamical response explaining the increase in the occurrence of HW. The anticyclonic anomaly over the Mediterranean basin is associated with drier soils and a reduction of cloud cover, which concomitantly induce a decrease (increase) of the latent (sensible) heat flux and an increase of the downward radiative fluxes over lands. The source mechanisms leading to the mid-troposphere anomalies over North Atlantic and its adjacent continents are discussed. It is found that both the tropical and extra-tropical parts of the AMV modulate the atmospheric circulation over the Euro-Atlantic region. The number of HW days increases linearly with the amplitude of the AMV. However, the strength of this relationship differs between the models, and depends on their intrinsic biases, raising questions regarding the robustness of the mechanisms of teleconnections associated with the AMV., Comment: submitted to Journal of Climate

Published
2020
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2. Teleconnection processes linking the intensity of the Atlantic Multidecadal Variability to the climate impacts over Europe in boreal winter

Author

Qasmi, Saïd, Cassou, Christophe, and Boé, Julien

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

The teleconnection between European climate and Atlantic Multidecadal Variability (AMV) remains difficult to isolate in observations because of internal variability and anthropogenically-forced signals. Using model sensitivity experiments proposed within the CMIP6/DCPP-C framework, the wintertime AMV/Europe teleconnection is investigated in large ensembles of pacemaker-type simulations in the CNRM-CM5 global circulation model. To evaluate the sensitivity of the model response to the AMV amplitude, experiments with AMV-forcing pattern multiplied by 2 and 3 (hereafter 2xAMV and 3xAMV, respectively) are performed in complement to the reference ensemble (1xAMV). Based on a flow analog method, the AMV-forced atmospheric circulation is found to cool down the European continent, whereas the residual signal, mostly including thermodynamical processes, contributes to warming. In 1xAMV, both terms cancel each other, explaining the overall weak AMV-forced atmospheric signal. In 2xAMV and 3xAMV, the thermodynamical contribution overcomes the dynamical cooling and is responsible for milder and wetter conditions. The thermodynamical term includes the advection of warmer and more humid oceanic air penetrating inland and the modification of surface radiative fluxes linked to (i) altered cloudiness and (ii) snow-cover reduction acting as a positive feedback with the AMV amplitude. The dynamical anomalous circulation combines (i) a remote response to enhanced diabatic heating acting as a Rossby-wave source in the western tropical Atlantic and (ii) a local response associated with warmer SST over the subpolar gyre favorizing an anomalous High. The weight between the tropical-extratropical processes and associated feedbacks is speculated to partly explain the nonlinear sensibility of the response to the AMV-forcing amplitude, challenging thus the use of the so-called pattern-scaling technique., Comment: 34 pages, 8 figures, submitted to Journal of Climate

Published
2019
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3. Pluri-annual Water Budget on the Seine Basin: Past, Current and Future Trends

Author

Flipo, Nicolas, Gallois, Nicolas, Labarthe, Baptiste, Baratelli, Fulvia, Viennot, Pascal, Schuite, Jonathan, Rivière, Agnès, Bonnet, Rémy, Boé, Julien, Hutzinger, Otto, Founding Editor, Barceló, Damià, Series Editor, Kostianoy, Andrey G., Series Editor, de Boer, Jacob, Editorial Board Member, Garrigues, Philippe, Editorial Board Member, Gu, Ji-Dong, Editorial Board Member, Jones, Kevin C., Editorial Board Member, Knepper, Thomas P., Editorial Board Member, Negm, Abdelazim M., Editorial Board Member, Newton, Alice, Editorial Board Member, Nghiem, Duc Long, Editorial Board Member, Garcia-Segura, Sergi, Editorial Board Member, Flipo, Nicolas, editor, Labadie, Pierre, editor, Lestel, Laurence, editor, Alligant, S., With Contri. by, Alliot, F., With Contri. by, Anglade, J., With Contri. by, Ansart, P., With Contri. by, Ayrault, S., With Contri. by, Azimi, S., With Contri. by, Baratelli, F., With Contri. by, Barjhoux, I., With Contri. by, Barles, S., With Contri. by, Beaudoin, N., With Contri. by, Belliard, J., With Contri. by, Benedetti, M. F., With Contri. by, Berthe, T., With Contri. by, Beslagic, S., With Contri. by, Bigot-Clivot, A., With Contri. by, Billen, G., With Contri. by, Blanchard, M., With Contri. by, Blanchoud, H., With Contri. by, Boé, J., With Contri. by, Bonnard, M., With Contri. by, Bonnet, R., With Contri. by, Boust, D., With Contri. by, Bressy, A., With Contri. by, Briand, C., With Contri. by, Brignon, J.-M., With Contri. by, Budzinski, H., With Contri. by, Carré, C., With Contri. by, Chevreuil, M., With Contri. by, Chong, N., With Contri. by, Collard, F., With Contri. by, Cordier, M.-A., With Contri. by, Dedourge-Geffard, O., With Contri. by, Derenne, S., With Contri. by, Deroubaix, J.-F., With Contri. by, Desportes, A., With Contri. by, Dris, R., With Contri. by, Eschbach, D., With Contri. by, Esculier, F., With Contri. by, Euzen, A., With Contri. by, Gallois, N., With Contri. by, Flipo, N., With Contri. by, Garnier, J., With Contri. by, Gasperi, J., With Contri. by, Gateuille, D., With Contri. by, Geffard, A., With Contri. by, Gelabert, A., With Contri. by, Gob, F., With Contri. by, Goffin, A., With Contri. by, Goutte, A., With Contri. by, Groleau, A., With Contri. by, Guigon, E., With Contri. by, Guillon, S., With Contri. by, Guo, Y., With Contri. by, Habets, F., With Contri. by, Haghe, J.-P., With Contri. by, Labadie, P., With Contri. by, Labarthe, B., With Contri. by, Le Noë, J., With Contri. by, Le Pichon, C., With Contri. by, Léonard, J., With Contri. by, Lestel, L., With Contri. by, Lorgeoux, C., With Contri. by, Louis, Y., With Contri. by, Lucas, F. S., With Contri. by, Marescaux, A., With Contri. by, Mary, B., With Contri. by, Matar, Z., With Contri. by, Meybeck, M., With Contri. by, Mignolet, C., With Contri. by, Moilleron, R., With Contri. by, Mouchel, J.-M., With Contri. by, Moulin, L., With Contri. by, Muresan, B., With Contri. by, Nguyen, P. T., With Contri. by, Oziol, L., With Contri. by, Palos-Ladeiro, M., With Contri. by, Parlanti, E., With Contri. by, Passy, P., With Contri. by, Petit, F., With Contri. by, Puech, T., With Contri. by, Queyrel, W., With Contri. by, Raimonet, M., With Contri. by, Riviére, A., With Contri. by, Rocher, V., With Contri. by, Schott, C., With Contri. by, Schuite, J., With Contri. by, Seguin, L., With Contri. by, Servais, P., With Contri. by, Silvestre, M., With Contri. by, Soares-Pereira, C., With Contri. by, Tales, E., With Contri. by, Tallec, G., With Contri. by, Tassin, B., With Contri. by, Teil, M.-J., With Contri. by, Théry, S., With Contri. by, Thevenot, D., With Contri. by, Thieu, V., With Contri. by, Tournebize, J., With Contri. by, Tramoy, R., With Contri. by, Treilles, R., With Contri. by, Varrault, G., With Contri. by, Viennot, P., With Contri. by, Vilmin, L., With Contri. by, and Wurtzer, S., With Contri. by

Published
2021
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10. Past long-term summer warming over western Europe in new generation climate models : role of large-scale atmospheric circulation

Author

Boe, Julien, Terray, Laurent, Moine, Marie-Pierre, Valcke, Sophie, Bellucci, Alessio, Drijfhout, Sybren, Haarsma, Rein, Lohmann, Katja, Putrasahan, Dian A., Roberts, Chris, Roberts, Malcom, Scoccimarro, Enrico, Seddon, Jon, Senan, Retish, Wyser, Klaus, Boe, Julien, Terray, Laurent, Moine, Marie-Pierre, Valcke, Sophie, Bellucci, Alessio, Drijfhout, Sybren, Haarsma, Rein, Lohmann, Katja, Putrasahan, Dian A., Roberts, Chris, Roberts, Malcom, Scoccimarro, Enrico, Seddon, Jon, Senan, Retish, and Wyser, Klaus

Published
2020
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11. Impact of Higher Spatial Atmospheric Resolution on Precipitation Extremes Over Land in Global Climate Models

Author

Bador, Margot, Boe, Julien, Terray, Laurent, Alexander, Lisa, V, Baker, Alexander, Bellucci, Alessio, Haarsma, Rein, Koenigk, Torben, Moine, Marie-Pierre, Lohmann, Katja, Putrasahan, Dian A., Roberts, Chris, Roberts, Malcolm, Scoccimarro, Enrico, Schiemann, Reinhard, Seddon, Jon, Senan, Retish, Valcke, Sophie, Vanniere, Benoit, Bador, Margot, Boe, Julien, Terray, Laurent, Alexander, Lisa, V, Baker, Alexander, Bellucci, Alessio, Haarsma, Rein, Koenigk, Torben, Moine, Marie-Pierre, Lohmann, Katja, Putrasahan, Dian A., Roberts, Chris, Roberts, Malcolm, Scoccimarro, Enrico, Schiemann, Reinhard, Seddon, Jon, Senan, Retish, Valcke, Sophie, and Vanniere, Benoit

Published
2020
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12. Climate change impacts on tree ranges: model intercomparison facilitates understanding and quantification of uncertainty

Author

Cheaib, Alissar, Badeau, Vincent, Boe, Julien, Chuine, Isabelle, Delire, Christine, Dufrene, Eric, Francois, Christophe, Gritti, Emmanuel S., Legay, Myriam, Page, Christian, Thuiller, Wilfried, Viovy, Nicolas, Leadley, Paul, Ecologie Systématique et Evolution (ESE), Université Paris-Sud - Paris 11 (UP11)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Ecologie et Ecophysiologie Forestières [devient SILVA en 2018] (EEF), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), Sci Univers CERFACS, URA 1875, Centre National de la Recherche Scientifique (CNRS), Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Université Paul-Valéry - Montpellier 3 (UPVM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut de Recherche pour le Développement (IRD [France-Sud]), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA), Université Joseph Fourier - Grenoble 1 (UJF)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Paul-Valéry - Montpellier 3 (UM3), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université Paul-Valéry - Montpellier 3 (UM3)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)

Subjects
Fagus sylvatica, MORTALITY, [SDV]Life Sciences [q-bio], Quercus petraea, PLANT GEOGRAPHY, species range, GLOBAL VEGETATION MODELS, PREDICTIONS, Pinus sylvestris, vegetation model intercomparison, EUROPEAN FOREST ECOSYSTEMS, Quercus ilex, CARBON, DISTRIBUTIONS, WATER, Climate change, BIODIVERSITY, France, Quercus robur, DROUGHT
Abstract

Model-based projections of shifts in tree species range due to climate change are becoming an important decision support tool for forest management. However, poorly evaluated sources of uncertainty require more scrutiny before relying heavily on models for decision-making. We evaluated uncertainty arising from differences in model formulations of tree response to climate change based on a rigorous intercomparison of projections of tree distributions in France. We compared eight models ranging from niche-based to process-based models. On average, models project large range contractions of temperate tree species in lowlands due to climate change. There was substantial disagreement between models for temperate broadleaf deciduous tree species, but differences in the capacity of models to account for rising CO2 impacts explained much of the disagreement. There was good quantitative agreement among models concerning the range contractions for Scots pine. For the dominant Mediterranean tree species, Holm oak, all models foresee substantial range expansion.

Published
2012
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13. Régimes de temps et désagrégation d'échelle

Author

Boe, Julien and Terray, Laurent

Abstract

Weather regimes and downscaling. Hydrological processes are characterized by time and spatial scales which strongly differ from those explicitly solved by climate models used in the framework of the fourth intergovernmental panel for climate change (IPCC) report. Many different statistical and/ or dynamical techniques have been developed to perform the downscaling process (going from a few hundred kilometres to resolution of five to twenty kilometres). Here we present a downscaling methodology based on weather regimes and its application to hydrological changes in France during the 21st century. We review the conceptual framework and the advantages of the method as well as the associated assumptions and uncertainties., Les échelles de temps et d’espace caractéristiques des processus hydrologiques différent fortement de celles résolues par les modèles climatiques utilisés pour les scénarios réalisés dans le cadre du 4ème rapport du groupe intergouvernemental d’experts sur l’évolution du climat (GIEC). De nombreuses techniques dynamique et/ou statistique ont été développées pour effectuer ce transfert d’échelle. Nous présentons une nouvelle méthode de désagrégation d’échelle basée sur les régimes de temps et son application à l’étude des scénarios hydro-climatiques futurs pour les grands bassins versant français. Nous montrerons le cadre conceptuel et les avantages de cette nouvelle méthode pour un certain nombre d’applications ainsi que les hypothèses et les incertitudes associées., Boe Julien, Terray Laurent. Régimes de temps et désagrégation d'échelle. In: Variations climatiques et hydrologie. Le climat, ses variations séculaires et ses changements pronostiqués : quel impact sur l'hydrologie (ressources en eau et évènements rares, étiages - crues). 29èmes Journées de l'Hydraulique. Congrès de la Société Hydrotechnique de France. Lyon, 27-28 mars 2007. 2007.

Published
2007

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