Catherine Gall

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• Type de publi. : Article dans une revue
• Date de publi. : 01/08/2023
• Auteurs : Manon AllaireRola Al-SayeghMorgane MabireAdel HammouteneMatthieu SiebertCharles CaërMathilde CadouxJinghong WanAida HabibMaude Le GallPierre de la GrangeHervé GuillouCatherine PosticValérie ParadisSophie LotersztajnHélène Gilgenkrantz
• Organismes : Centre de recherche sur l'Inflammation CHU Pitié-Salpêtrière [AP-HP] Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Hôpital Beaujon [AP-HP] Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation AP-HP - Hôpital Bichat - Claude Bernard [Paris] Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Qatar University Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] GenoSplice [Paris] ToxAlim Institut Cochin Centre de recherche sur l'Inflammation Hôpital Beaujon [AP-HP] Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris] Centre de recherche sur l'Inflammation Laboratoire d'Excellence Inflamex [Paris]
• Publié dans JHEP Reports Innovation in Hepatology le 07/09/2020

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Résumé : Background & aims: Liver regeneration is a repair process in which metabolic reprogramming of parenchymal and inflammatory cells plays a major role. Monoacylglycerol lipase (MAGL) is an ubiquitous enzyme at the crossroad between lipid metabolism and inflammation. It converts monoacylglycerols into free fatty acids and metabolises 2-arachidonoylglycerol into arachidonic acid, being thus the major source of pro-inflammatory prostaglandins in the liver. In this study, we investigated the role of MAGL in liver regeneration. Methods: Hepatocyte proliferation was studied in vitro in hepatoma cell lines and ex vivo in precision-cut human liver slices. Liver regeneration was investigated in mice treated with a pharmacological MAGL inhibitor, MJN110, as well as in animals globally invalidated for MAGL (MAGL-/-) and specifically invalidated in hepatocytes (MAGLHep-/-) or myeloid cells (MAGLMye-/-). Two models of liver regeneration were used: acute toxic carbon tetrachloride injection and two-thirds partial hepatectomy. MAGLMye-/- liver macrophages profiling was analysed by RNA sequencing. A rescue experiment was performed by in vivo administration of interferon receptor antibody in MAGLMye-/- mice. Results: Precision-cut human liver slices from patients with chronic liver disease and human hepatocyte cell lines exposed to MJN110 showed reduced hepatocyte proliferation. Mice with global invalidation or mice treated with MJN110 showed blunted liver regeneration. Moreover, mice with specific deletion of MAGL in either hepatocytes or myeloid cells displayed delayed liver regeneration. Mechanistically, MAGLHep-/- mice showed reduced liver eicosanoid production, in particular prostaglandin E2 that negatively impacts on hepatocyte proliferation. MAGL inhibition in macrophages resulted in the induction of the type I interferon pathway. Importantly, neutralising the type I interferon pathway restored liver regeneration of MAGLMye-/- mice. Conclusions: Our data demonstrate that MAGL promotes liver regeneration by hepatocyte and macrophage reprogramming. Impact and implications: By using human liver samples and mouse models of global or specific cell type invalidation, we show that the monoacylglycerol pathway plays an essential role in liver regeneration. We unveil the mechanisms by which MAGL expressed in both hepatocytes and macrophages impacts the liver regeneration process, via eicosanoid production by hepatocytes and the modulation of the macrophage interferon pathway profile that restrains hepatocyte proliferation.

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• Type de publi. :
• Date de publi. : 04/07/2023
• Auteurs : Kilian Le GallLaurent LemarchandCatherine Dezan
• Organismes : Equipe Software/HArdware and unKnown Environment inteRactions Equipe Software/HArdware and unKnown Environment inteRactions Equipe Software/HArdware and unKnown Environment inteRactions

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Résumé : L'utilisation de drones pour des tâches d'exploration exige une adaptation dynamique à l'environnement. Une stratégie d'évitement est nécessaire pour éviter les collisions. Notre cas d'étude est un drone flottant exploité pour surveiller une zone portuaire à l'aide d'un lidar. Nous devons définir la route suivie par le drone. Cette mission (suite de waypoints définissant une route) est générée à l'aide d'un algorithme évolutionnaire multi-objectifs (PAES)qui dans le même temps produit une archive de solutions. La qualité de chaque solution est évaluée par deux objectifs à minimiser contradictoires, la distance parcourue et la surface non couverte par le lidar. PAES produit en ensemble de solutions non dominées (une solution est dite dominante par rapport à une autre si ses deux fonctions objectives sont meilleures), considérées comme des bons compromis selon les critères de la mission. Un algorithme décisionnel multicritères (TOPSIS) choisit ensuite la meilleure trajectoire pour la mission. En cours de mission, lorsqu'un obstacle survient, une première stratégie (SPNW) consiste à contourner l'obstacle jusqu'au waypoint suivant en empruntant le chemin le plus court. Toutefois, cette méthode peut conduire le drone à repasser par des zones déjà couvertes. La seconde stratégie (RFA) consiste à réutiliser l'archive PAES. Chacune des solutions qu'elle contient est combinée avec la route et la position courante en évitant l'obstacle. TOPSIS sélectionne ensuite une des combinaisons pour achever la mission. Pour une série de 1000 cas de tests, en comparant les résultats obtenus, on observe que TOPSIS choisit la solution produite par RFA dans 75% des cas. Dans 10% des cas, la solution RFA domine même la solution produite avec SPNW. Cependant SPNW est beaucoup moins coûteux en temps d'exécution (3 ms contre 399 ms pour RFA). En exploitant uniquement une partie de l'archive PAES, il est possible de réduire le temps de calcul de RFA tout en restant compétitif par rapport à SPNW. Par exemple, en exploitant uniquement la moitié de l'archive, TOPSIS choisit encore la solution RFA dans 68% des cas et s'exécute en 206 ms. La solution RFA offre donc une perspective d'optimisation de trajectoire intéressante pour des versions embarquées et temps réel. *. Ce travail est possible grâce au laboratoire commun Thales/Lab-STICC LATERAL.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 27/06/2023
• Auteurs : Kilian Le GallLaurent LemarchandCatherine Dezan
• Organismes : Equipe Software/HArdware and unKnown Environment inteRactions Equipe Software/HArdware and unKnown Environment inteRactions Equipe Software/HArdware and unKnown Environment inteRactions

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Résumé : Autonomous vehicles are well-known for automated tasks that are difficult or dangerous to be performed by human. However, the environment in which those Autonomous Vehicle (AV) are evolving is generally hard to predict. Thus, the challenge is to achieve a predefined mission while adapting AVs to their shifting environment in real time as efficiently as possible. The mission often includes path planning problems, where self-adaptation to terrain modifications is required while maintaining contradictory objectives, such as safety, risk assessment, travelling time or distance or consumed energy. We choose to focus on supervision missions (covering area with a lidar, with pictures, searching, etc) with two objectives: travelled distance (that could later be modeled into time or energy consumption) and covered area. We propose a multiobjective optimization (MOO) framework for a self adaptation of autonomous vehicles, with an offline/online approach, in order to solve covering/monitoring missions. The offline process will predict a initial path for the AV and the online process will be useful for the dynamic path re-planning when obstacles are detected. Our results demonstrate the benefits of reusing the offline pre-computed solutions for the online phase and for dynamic path re-planning.

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Fichiers liés : ssiv2023porto.pdf

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• Type de publi. : Rapport
• Date de publi. : 01/03/2023
• Auteurs : Carlos MorenoCatherine GallDidier ChabaudMarine GarnierMasson IllianFlorent Pratlong
• Organismes : IAE Paris - Sorbonne Business School IAE Paris - Sorbonne Business School IAE Paris - Sorbonne Business School IAE Paris - Sorbonne Business School IAE Paris - Sorbonne Business School Université Paris 1 Panthéon-Sorbonne - École de Management de la Sorbonne

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Fichiers liés : ETI Chair White-Paper-3 EN.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2023
• Auteurs : Josselin BaumardMathieu LesourdChristophe JarryCatherine MerckFrédérique Etcharry-BouyxValérie ChauviréSerge BelliardFrançois OsiurakDidier Le Gall
• Organismes : Centre de Recherche sur les Fonctionnement et les Dysfonctionnements Psychologiques Laboratoire de Neurosciences Intégratives et Cliniques - UFC (UR 481) Maison des Sciences de l'Homme et de l'Environnement Claude Nicolas Ledoux (UAR 3124) Laboratoire de Psychologie des Pays de la Loire Service de neurologie [Rennes] Centre Hospitalier Universitaire d'Angers Service de neurologie [Angers] Department of Neurology, Centre Hospitalier Régional et Universitaire de Rennes Laboratoire de Psychologie Processus de Pensée et Interventions Laboratoire d'Etude des Mécanismes Cognitifs Institut Universitaire de France Laboratoire de Psychologie des Pays de la Loire
• Publié dans Journal of the International Neuropsychological Society le 27/10/2020

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Résumé : Abstract Objective: Semantic tool knowledge underlies the ability to perform activities of daily living. Models of apraxia have emphasized the role of functional knowledge about the action performed with tools (e.g., a hammer and a mallet allow a “hammering” action), and contextual knowledge informing individuals about where to find tools in the social space (e.g., a hammer and a mallet can be found in a workshop). The goal of this study was to test whether contextual or functional knowledge, would be central in the organization of tool knowledge. It was assumed that contextual knowledge would be more salient than functional knowledge for healthy controls and that patients with dementia would show impaired contextual knowledge. Methods: We created an original, open-ended categorization task with ambiguity, in which the same familiar tools could be matched on either contextual or functional criteria. Results: In our findings, healthy controls prioritized a contextual, over a functional criterion. Patients with dementia had normal visual categorization skills (as demonstrated by an original picture categorization task), yet they made less contextual, but more functional associations than healthy controls. Conclusion: The findings support a dissociation between functional knowledge (“what for”) on the one hand, and contextual knowledge (“where”) on the other hand. While functional knowledge may be distributed across semantic and action-related factors, contextual knowledge may actually be the name of higher-order social norms applied to tool knowledge. These findings may encourage researchers to test both functional and contextual knowledge to diagnose semantic deficits and to use open-ended categorization tests.

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Fichiers liés : 2023 Baumard - Manuscript JINS_R2_HAL.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/12/2022
• Auteurs : Sara ThietartAriane BoumendilDominique PateronBertrand GuidetH. ValletBertrand GuidetDominique PateronErwan DebucYouri YordanovAriane BoumendilCaroline ThomasDidier DreyfussJean-Damien RicardPatrick BrunChristophe LeroyYves CohenFrédéric AdnetMaguy WoimantJean-Paul MiraBenoît DoumencKhalil TkuThomas SimilowskiBruno RiouPierre HausfaterSamuel DelermeJean-Pierre QuenotDidier HonnartJean-François TimsitPierrick GuérinFrançoise CarpentierMaxime MaignanFoued MakhlouJean-François PousselYohann PicardFrançois BraunPauline TrognonFrançois FourrierPatrick GoldsteinMarie GirotPierre GosselinFrancesco SantoliPierre CharestanClaire PolyHervé MentecCatherine Le GallKarima SahraouiChristophe BaillardNicolas JavaudBenoît MissetMaité Garrouste-OrgeasOlivier GanansiaFrançois-Xavier RooryckJean Luc AimAbudlrazak El RifaiJean ReignierLaurent Martin-LefevrePhilippe FradinClaire MauriatEmelyne CwicklinskiMichel SlamaHervé DupontChristine AmmiratiJustine GallouMuriel FartoukhMichel DjibrePatrik RayEdwin RouffBertrand SouweineAli Ait HssainJeannot SchmidtDaniel PicFarès MoustafaAlain MercatNicolas LerollePierre-Marie RoyFrédéric BaudPatrick PlaisanceSophie MontagnonBertrand GalichonMichel WolffBruno MourvillierEnrique CasalinoChristophe ChoquetJulien BernardGaëlle JuillienJean-Yves FagonEmmanuel GuerotPhilippe JuvinAnabela PatzakBruno VerdièreVincent IoosMarie-Clément KoukaAudrey BerthoumieuChristian RichardRaphael MauriceSophie SarnelStéphane DiezAntoine Vieillard BaronSébastien BeauneJulie GrenetSylvie AzeradGuillaume LeblancTabassome Simon
• Organismes : CHU Saint-Antoine [AP-HP] CHU Saint-Antoine [AP-HP] CHU Saint-Antoine [AP-HP] CHU Saint-Antoine [AP-HP] Institut Pierre Louis d'Epidémiologie et de Santé Publique Centre d'Immunologie et des Maladies Infectieuses CHU Saint-Antoine [AP-HP] CHU Saint-Antoine [AP-HP] Institut Pierre Louis d'Epidémiologie et de Santé Publique CHU Saint-Antoine [AP-HP] Assistance publique - Hôpitaux de Paris (AP-HP) Institut Pierre Louis d'Epidémiologie et de Santé Publique CHU Saint-Antoine [AP-HP] Institut Pierre Louis d'Epidémiologie et de Santé Publique CHU Saint-Antoine [AP-HP] Musée du Louvre Hôpital Louis Mourier - AP-HP [Colombes] Maladies rénales fréquentes et rares : des mécanismes moléculaires à la médecine personnalisée Hôpital d'instruction des Armées Percy Assistance publique - Hôpitaux de Paris (AP-HP) Hôpital Avicenne [AP-HP] Hôpital Avicenne [AP-HP] SAMU 93 [Bobigny] Marqueurs cardiovasculaires en situation de stress Hôpital Avicenne [AP-HP] Institut Cochin Hôpital Cochin [AP-HP] AP-HP - Hôpital Cochin Broca Hôtel Dieu [Paris] Neurophysiologie Respiratoire Expérimentale et Clinique CHU Pitié-Salpêtrière [AP-HP] Unité de Recherche sur les Maladies Cardiovasculaires, du Métabolisme et de la Nutrition = Research Unit on Cardiovascular and Metabolic Diseases Groupe de recherche clinique Biomarqueurs d’urgence et de réanimation Centre d'Immunologie et des Maladies Infectieuses CHU Dijon Centre d'Investigation Clinique 1432 (Dijon) - Epidemiologie Clinique/Essais Cliniques Département de Médecine d'Urgence - Centre Régional Universitaire des Urgences (CRUU) (CHU de Dijon) AP-HP - Hôpital Bichat - Claude Bernard [Paris] Infection, Anti-microbiens, Modélisation, Evolution Service d'accueil des urgences médicales Université Grenoble Alpes Service de Soins Intensifs [CHR Metz-Thionville] Centre hospitalier régional Metz-Thionville Université Henri Poincaré - Nancy 1 Département Anesthésie-Réanimation, Hôpital Roger Salengro, CHRU de Lille Samu du Nord–pôle de l’urgence [Lille] Department of Emergency [Lille] Institut Fourier Hôpital Robert Ballanger [Aulnay-sous-Bois] Hôpital Robert Ballanger [Aulnay-sous-Bois] Centre Hospitalier Victor Dupouy Centre hospitalier Argenteuil Hôpital Cochin [AP-HP] Hôpital Louis Mourier - AP-HP [Colombes] Centre de référence national des angiœdèmes Université Paris Cité Centre Hospitalier Universitaire de Liège Institut hospitalier Franco-Britannique [Levallois-Perret] Hôpital Saint-Joseph Centre hospitalier universitaire de Nantes
• Publié dans Annals of Intensive Care le 23/10/2020

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Résumé : Abstract Background Little is known about the impact of hospital trajectory on survival and functional decline of older critically ill patients. We evaluate 6-month outcomes after admission to: intensive care units (ICU), intermediate care units (IMCU) or acute medical wards (AMW). Methods Data from the randomised prospective multicentre clinical trial ICE-CUB2 was secondarily analysed. Inclusion criteria were: presenting at emergency departments in critical condition; age ≥ 75 years; activity of daily living (ADL) ≥ 4; preserved nutritional status; and no active cancer. A Cox model was fitted to compare survival according to admission destination adjusting for patient characteristics. Sensitivity analysis using multiple imputation for missing data and propensity score matching were performed. Results Among 3036 patients, 1675 (55%) were women; median age was 85 [81–99] years; simplified acute physiology score (SAPS-3) 62 [55–69]; 1448 (47%) were hospitalised in an ICU, 504 in IMCU (17%), and 1084 (36%) in AMW. Six-month mortality was 629 (44%), 155 (31%) and 489 (45%) after admission in an ICU, IMCU and AMW ( p < 0.001), respectively. In multivariate analysis, AMW admission was associated with worse 6-month survival (HR 1.31, 95% CI 1.04–1.63) in comparison with IMCU admission, after adjusting for age, gender, comorbidities, ADL, SAPS-3 and diagnosis. Survival was not significantly different between patients admitted in an ICU and an IMCU (HR 1.17, 95% CI 0.95–1.46). Sensitivity analysis using multiple imputation for missing data and propensity score matching found similar results. Hospital destination was not significantly associated with the composite criterion loss of 1-point ADL or mortality. Physical and mental components of the 12-Item Short-Form Health Survey were significantly lower in the acute medical ward group (34.3 [27.5–41.7], p = 0.037 and 44.3 [38.6–48.6], p = 0.028, respectively) than in the ICU group (34.7 [28.4–45.3] and 45.5 [40.0–50.0], respectively) and IMCU group (35.7 [29.7–43.8] and 44.5 [39.7–48.4], respectively). Conclusions Admission in an AMW was associated with worse 6-month survival in older critically ill patients in comparison with IMCU admission, with no difference of survival between ICU and IMCU admission. There were no clinically relevant differences in quality of life in each group. These results should be confirmed in specific studies and raise the question of dedicated geriatric IMCUs.

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Fichiers liés : s13613-022-01042-4.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/11/2022
• Auteurs : Quentin DeshoullesMaelenn Le GallS. BenaliJ-M. RaquezCatherine DreannoMael ArhantDaniel PriourS. CerantolaG. StocletPierre‐yves Le Gac
• Organismes : Laboratoire Comportement des Structures en Mer Laboratoire Comportement des Structures en Mer Laboratoire Détection Capteurs et Mesure Laboratoire Comportement des Structures en Mer Laboratoire Comportement des Structures en Mer Laboratoire Comportement des Structures en Mer
• Publié dans Polymer Degradation and Stability le 02/11/2020

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Résumé : The long-term behaviour of PBAT subjected to hydrolytic ageing is investigated in this paper. Samples were aged in water at several temperatures ranging from 80 to 100°C for different durations. Changes in physico-chemical properties were investigated through NMR, GPC, DSC and X-Ray analyses and embrittlement was assessed by tensile tests. It is demonstrated that hydrolysis of PBAT occurs first on the ester group located between the terephthalate and adipate groups leading to a decrease in molar mass. For longer ageing durations, the ester situated within the adipate group undergoes hydrolysis. An increase in crystallinity ratio and a decrease in amorphous layer thickness was observed as consequences of the chain scission process. Finally, a clear change in mechanical behaviour is noted; for the early stages of ageing, the polymer exhibits a ductile behaviour while for longer ageing durations, the polymer is brittle due to a lack of chain entanglement. This transition takes place once the molar mass of PBAT falls below 11 kg/mol, i.e. when a critical molar mass M’c is reached.

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• Type de publi. : Article dans une revue
• Date de publi. : 20/10/2022
• Auteurs : Flavienne BruyantRémi AmirauxMarie-Pier AmyotPhilippe ArchambaultLise ArtigueLucas Bardedo de FreitasGuislain BécuSimon BélangerPascaline BourgainAnnick BricaudEtienne BrouardCamille BrunetTonya BurgersDanielle CalebKatrine ChalutHervé ClaustreVéronique Cornet-BarthauxPierre Vincent CoupelMarine CusaFanny CussetLaeticia DadaglioMarty DavelaarGabriele DeslongchampsCéline DimierJulie DinasquetDany DumontBrent ElseIgor EulaersJoannie FerlandGabrielle FilteauMarie-Hélène ForgetJérôme FortLouis FortierMartí Galí-TapíasMorgane GallinariSvend-Erik GarbusNicole GarciaCatherine Gérikas RibeiroColline GombaultPriscillia GourvilClémence GoyensCindy GrantPierre-Luc GrondinPascal GuillotSandrine HillionRachel HussherFabien JouxHannah Joy-WarrenGabriel JoyalDavid KieberAugustin LafondJosé LagunasPatrick LajeunesseCatherine LalandeJade LarivièreFlorence Le GallKarine LeblancMathieu LeblancJustine LegrasKeith LevesqueKate-Marie LewisEdouard LeymarieAude LeynaertThomas LinkowskiMartine LizotteAdriana Lopes dos SantosClaudie MarecDominique MarieGuillaume MasséPhilippe MassicotteAtsushi MatsuokaLisa MillerSharif MirshakNathalie MorataBrivaëla MoriceauPhilippe-Israël MorinSimon MorissetAnders MosbechAlfonso MucciGabrielle NadaïChristian NozaisIngrid ObernostererTimothe PaireChristos PanagiotopoulosMarie ParenteauNoémie PelletierMarc PicheralBernard QueguinerPatrick RaimbaultJoséphine RasEric RehmLlúcia Ribot LacostaJean-François RontaniBlanche Saint-BéatJulie SansouletNoé SardetCatherine SchmechtigAntoine SciandraRichard SempereCaroline SévignyJordan ToullecMargot TraginJean-Eric TremblayAnnie-Pier TrottierDaniel VaulotAnda VladoiuLei XueGustavo Yunda-GuarinMarcel Babin
• Organismes : Laboratoire d'océanographie de Villefranche Laboratoire d'océanographie de Villefranche LIttoral ENvironnement et Sociétés Institut de la Mer de Villefranche LIttoral ENvironnement et Sociétés Fédération de recherche de Roscoff Station biologique de Roscoff = Roscoff Marine Station Laboratoire d'Océanographie Microbienne Fédération de recherche de Roscoff Station biologique de Roscoff = Roscoff Marine Station Laboratoire d'océanographie de Villefranche Laboratoire d'océanographie de Villefranche Laboratoire d'océanographie de Villefranche Takuvik Joint International Laboratory ULAVAL-CNRS
• Publié dans Earth System Science Data le 23/10/2020

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Résumé : Abstract. The Green Edge project was designed to investigate the onset, life and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in arctic ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the arctic environment will affect it. Green Edge was a large multidisciplinary collaborative project bringing researchers and technicians from 28 different institutions in seven countries, together aiming at understanding these changes and their impacts into the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice-camp and a research vessel in the Baffin Bay, canadian arctic. This paper describes the sampling strategy and the data set obtained from the research cruise, which took place aboard the Canadian Coast Guard Ship (CCGS) Amundsen in spring 2016. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a).

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Fichiers liés : Bruyant et al 2022 ESSD HAL.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/09/2022
• Auteurs : Pauline RivoirePhilomène Le GallAnne-Catherine FavrePhilippe NaveauOlivia Martius
• Organismes : Oeschger Centre for Climate Change Research Institut des Géosciences de l’Environnement Institut des Géosciences de l’Environnement Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] Extrèmes : Statistiques, Impacts et Régionalisation Universität Bern [Bern]
• Publié dans Weather and Climate Extremes le 01/11/2020

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Résumé : Accurate estimation of daily rainfall return levels associated with large return periods is needed for a number of hydrological planning purposes, including protective infrastructure, dams, and retention basins. This is especially relevant at small spatial scales. The ERA-5 reanalysis product provides seasonal daily precipitation over Europe on a 0.25 • ×0.25 • grid (about 27 × 27 [km]). This translates more than 20,000 land grid points and leads to models with a large number of parameters when estimating return levels. To bypass this abundance of parameters, we build on the regional frequency analysis (RFA), a well-known strategy in statistical hydrology. This approach consists in identifying homogeneous regions, by gathering locations with similar distributions of extremes up to a normalizing factor and developing sparse regional models. In particular, we propose a step-bystep blueprint that leverages a recently developed and fast clustering algorithm to infer return level estimates over large spatial domains. This enables us to produce maps of return level estimates of ERA-5 reanalysis daily precipitation over continental Europe for various return periods and seasons. We discuss limitations and practical challenges and also provide a git hub repository. We show that a relatively parsimonious model with only a spatially varying scale parameter can compete well against statistical models of higher complexity.

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Fichiers liés : 1-s2.0-S2212094722000792-main.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/06/2022
• Auteurs : Philomène Le GallAnne-Catherine FavrePhilippe NaveauClémentine Prieur
• Organismes : Institut des Géosciences de l’Environnement Institut des Géosciences de l’Environnement Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] Mathematics and computing applied to oceanic and atmospheric flows
• Publié dans Weather and Climate Extremes le 01/11/2020

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Résumé : Rainfall are subject to local orography features and their intensities can be highly variable. In this context, identifying climatically coherent regions can greatly help interpreting rainfall patterns and improve the inference of return levels. In practice, partitioning a region of interest into homogeneous sub-regions is a delicate statistical task, especially in regards to modeling heavy rainfall features. In this work, our main goal is to propose and study a fast and efficient clustering algorithm. Compared to classical regional frequency analysis techniques, a key aspect is that our algorithm does not rely on the a priori choice of covariates. The proposed numerical scheme is only based on the precipitation dataset at hand, including low, moderate and heavy rainfall. In terms of inference, our approach builds on the easy-to-compute and reliable probability weighted moments commonly used in hydrology. While being in compliance with extreme value theory, we do not impose a parametric form on rainfall distributions and, neither thresholding nor block maxima steps are required in our proposed approach. By construction, our clustering method preserves the scale invariance principle of any classical regional frequency analysis. The performance of our clustering algorithm is assessed on a detailed experimental design based on the extended Generalized Pareto distribution. Sensitivity to the number of clusters is carefully analyzed. We apply our clustering algorithm on Switzerland daily precipitation measured at 191 sites. The found homogeneous regions are consistent with local orography and our approach outperforms the classical regional frequency analysis based on normalized elevation and coordinates as covariates. To complete our analysis of Swiss rainfall, we propose three models based on our clustering outputs. A comparison between our local, semi-regional and regional models indicates that a relatively simple model with two clusters and a spatially varying scale parameter can compete very well against complex models.

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Fichiers liés : 1-s2.0-S221209472200038X-main.pdf

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