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Groupe de Travail Climat - Mécanique statistique


Le Groupe de Travail Climat - Mecanique Statistique a été créé par l'équipe ESTIMR (Extrèmes : Statistiques, Impacts et Regionalisations) du Laboratoire LSCE et l'équipe SphYNX du  SPEC avec l'objectif de promouvoir les échanges entre les chercheurs qui travaillent à l'interface de ces deux sujets.

La participation est libre, les rencontres sont très informelles. Pour plus d'informations et nous contacter: robin.noyelle[at] &  davide.faranda[at] (site web)

Prochaines Rencontres

- 11/10/2022 - 14h00 Justin Finkel (MIT, USA)

Transition path theory for rare event exploration: elucidating the critical dynamics of polar vortex breakdown 

The weather is said to have "a mind of its own", as a chaotic system with limited predictability. Yet its fluctuations remain largely confined to a familiar probability distribution, to which the built and natural environment is well adapted. More impactful are the extreme, intermittent fluctuations of temperature, moisture, and wind, which can seriously threaten ill-equipped human and ecological communities. Extreme events have "dynamics of their own" which are difficult to quantify because they play out in a far tail of the probability distribution, and so sample sizes are limited in both observations and simulations.

Nonetheless, nononequilibrium statistical mechanics provide some general laws for the progression of rare events. In particular, transition path theory (TPT) formulates the ensemble of rare events as a flow of probability current through a high-dimensional phase space, climbing a landscape called the committor function which quantifies progress toward the event and distinguishes the dominant physical mechanisms at each step. In this talk I will present a TPT analysis of a particular atmospheric phenomenon, sudden stratospheric warming (SSW): a premature collapse of the stratospheric polar vortex whose impacts propagate down to the surface and manifest in midlatitude cold air outbreaks. In an idealized model setting, we use enhanced sampling and coarse-graining to piece together the probability current from a patchwork of short simulations. Equipped with physical features informed by wave-mean flow interaction theory, our data-driven procedure makes precise the role of stochastic forcing in driving the enstrophy transfer from mean flow to waves that destroys the polar vortex, and the altitude dependence of each process. Our computation and visualization methods, we believe, can enhance our understanding of many kinds of extreme events in the climate system.

Rencontres Passées

19/07/2022 Valentin Wendling (Institut de recherche pour le développement, France) "Tipping points in hydrology: observed regional regime shift and
System Dynamics modeling"

13/06/2022 Tommaso Alberti (Istituto di Astrofisica e Planetologia Spazial, Italy): "Chameleon attractors in turbulence"

06/04/2022 Reik Donner (Potsdam Institute for Climate Impact Research, Germany): "Spatiotemporal variability pattterns and teleconnections in the global 
climate system: complex network and causal discovery perspectives"

10/02/2022 Vera Mélinda Galfi (Uppsala University, Sweden): "A large deviation theory-based analysis of persistent atmospheric extreme events"

09/12/2021 Abhishek Harikrishnan (Freie Universität, Berlin): "Geometry and organization of coherent structures in turbulent flows"

21/10/2021 Caroline Wormell (Laboratoire de Probabilités, Statistique et Modélisation, Sorbonne Université, Paris): "Linear response in high-dimensional globally coupled systems"

02/09/2021 Courtney Quinn (CSIRO Oceans and Atmosphere, Hobart AU): "Dynamical analysis of data-driven reduced models for persistent atmospheric states" 
29/06/2021 Lucas Fery (LSCE-SPEC-CEA, France): "Latent Dirichlet Allocation technique for Atmospheric Circulation" 

30/03/2021 Bérengère Podvin (LIMSI, France): "Modèles pour la convection avec rayonnement"
11/01/2021 Valerio Lucarini (University of Reading, UK): "Fingerprinting Heatwaves and Cold Spells and Assessing Their Response to Climate Change using Large Deviation Theory"
05/10/2020 Hugues Faller (SPEC-SphynX,France): "On the nature of intermittency in a turbulent von Kármán flow"    
7/06/2020 Amaury Barral  (SPEC-CEA France): "Peut on simuler le climat avec un ordinateur portable?" 
07/04/2020 Alizee Chemison (LSCE, France)  "Impact of a rapid ice-sheet destabilisation on malaria burden in Africa" 
09-11/03/2020 "Workshop on Energetics and Drivers of Extreme Convective Events" (le lien ouvre le programme et les presentations)

13/02/2020 Vincent Labarre (LSCE-SPEC, France): "Maximum Entropy Production and Coarse Grain in conceptual climate & turbulent models" 

27-29/11/2019 Workshop: "Rencontre distribution des événements extrêmes application a la climatologie"

​​​​​​05/11/2019 Valerio Lucarini (University of Reading, UK): "A New Mathematical Framework for Atmospheric Blocking Events"
28/10/2019 Adriano Gualandi (JPL,NASA,USA): "Geodetic imaging of tectonic deformation: implications for earthquakes predictability"
16/09/2019 Raphaël Raynaud (Dap-CEA,France): "Anisotropie du transport de chaleur entre les pôles et l’équateur dans des modèles de convection dans une coquille sphérique en rotation"

16/04/2019 Sebastien Fromang (Irfu/Dap-CEA,France): "Aquaplanet simulations with Dynamico: the subtle effect of the horizontal dissipation"
07/02/2019 Hugues Faller (SPEC-SphynX,France): "Numerical VS exeprimental stuides of von Karman Flow"
23/11/2018 Ted Shepherd (University of Reading, UK): "Ethics and the construction of regional climate-change information"
08-09/10/2018 Workshop: "Dynamical Systems in Climate Sciences" 
​​​​​​    -Yuzuru Sato (Hokkaido University, Sapporo, Japan) - Stochastic bifurcations in random dynamical systems
    -Francesco Ragone (ENS Lyon, France) - Simulation Simulation of extreme European Heat Waves with rare events algorithms
    -Berengere Dubrulle/Francois Daviaud (SPEC-CNRS-CEA Saclay, France) - Stochastic Chaos in a turbulent swirling flow
    -Nikki Vercauteren (Freie Universitaet Berlin, Germany) - Scale Interactions and anisotropy of turbulence in stable boundary layers
    -Stephane Vannitsem (RMI- Bruxelles, Belgium) - Is ocean surface wind stress key in the long term predictability of the atmosphere
    -Sandro Vaienti/Theo Caby (CPT Marseille, France) - Generalized dimensions as a tool to study the penultimate attractor
    -Davide Faranda (LSCE IPSL CNRS, France) - Dynamical indicators to study atmospheric flows and climate change
25/05/2018 Henri Benisty (Institut d'Optique,France) & Hervé Bercegol (SPEC-SphynX,France): "​​​Statistical mechanics as a tool to understand the role of energy in the economy"
04/04/2018 Valerio Lucarini (UniReading, UK): "Constructing and Testing Parametrizations of Unresolved Processes in GFD"
12/03/2018 Sebastien Fromang (LSCE-CEA,France): "Transition between blocked and zonal flows in a rotating flow with bottom topography"
12/01/2018 Christophe Goupil (LIED, Paris,France): "From thermoelectricity to finite time thermodynamics: a closed loop approach to thermodynamics"
23/11/2017 Yuzuru Sato (Hokkaido University,Japan): "Anomalous diffusion in random dynamical systems"
03/10/2017 Nicholas Moloney (London Mathematical Laboratory,UK): "ELO rating system in Chess"
06/07/2017 Stefan Wieland (SPEC - SphynX,France): "The form of steady states in power transmission grids"
17/05/2017 Emmanuel Mouche (LSCE-CEA,France): "Modelisation des pics de crue comme phenomenes critiques: de la theorie des files d'attente à la physique statistique"
2/02/2017 Alexis Tantet (Uni Hamburg,Germany): "Ergodic Theory of climate: variability, stability and response"
14/12/2016 Carmen Alvarez-Castro (LSCE-CEA,France): "Changes in the atmospheric dynamics leading to West-European heatwaves since 1900."
15/11/2016 Workshop: "Applications of statistical-mechanics and dynamical systems to climate"
21/09/2016  Berengere Dubrulle (SPEC-SphynX,France): "Mieux maîtriser la turbulence : première observation d'événements singuliers de dissipation de l'énergie"
12/07/2016  Didier Paillard (LSCE-CEA,France): "CliMEP : un modèle de climat basé sur la maximisation de la production d'entropie"
13/04/2016  Guillaume Nevo (SPEC-SphynX,France): "Prevision et detection des crises dans les systèmes complexes"
05/02/2016  Yoann Robin (LSCE-CEA,France): "Pistes et Resultats sur l'utilisation de la Distance de Wasserstein"
08/12/2015  Berengere Dubrulle (SPEC-SphynX,France): "Vers une compréhension du principe de maximisation de production d'entropie"
15/10/2015  Hervé Bercegol (SPEC-SphynX,France): "Rayonnement électromagnétique, collisions inélastiques et production d'entropie"
16/06/2015  Pierre Sepulchre (LSCE-CEA,France): "La modélisation des niches écologiques"
23/03/2015  Alexandre Pohl & Gilles Ramstein (LSCE-CEA,France): "Régulations et déregulations du Climat aux grandes échelles de temps"
05/01/2015  Didier Paillard (LSCE-CEA,France) : "les mystères des abysses..." 
#183 - : 25/09/2022
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