no code implementations • 18 Mar 2023 • Sibo Cheng, Cesar Quilodran-Casas, Said Ouala, Alban Farchi, Che Liu, Pierre Tandeo, Ronan Fablet, Didier Lucor, Bertrand Iooss, Julien Brajard, Dunhui Xiao, Tijana Janjic, Weiping Ding, Yike Guo, Alberto Carrassi, Marc Bocquet, Rossella Arcucci
Data Assimilation (DA) and Uncertainty quantification (UQ) are extensively used in analysing and reducing error propagation in high-dimensional spatial-temporal dynamics.
no code implementations • 17 Nov 2022 • Arthur Filoche, Julien Brajard, Anastase Charantonis, Dominique Béréziat
Variational data assimilation and deep learning share many algorithmic aspects in common.
no code implementations • 4 Sep 2021 • Sébastien Barthélémy, Julien Brajard, Laurent Bertino, François Counillon
Increasing the resolution of a model can improve the performance of a data assimilation system: first because model field are in better agreement with high resolution observations, then the corrections are better sustained and, with ensemble data assimilation, the forecast error covariances are improved.
no code implementations • 26 Apr 2021 • Maike Sonnewald, Redouane Lguensat, Daniel C. Jones, Peter D. Dueben, Julien Brajard, Venkatramani Balaji
Progress within physical oceanography has been concurrent with the increasing sophistication of tools available for its study.
1 code implementation • 9 Dec 2020 • Vincent Bouget, Dominique Béréziat, Julien Brajard, Anastase Charantonis, Arthur Filoche
The network was compared to a similar architecture trained only on radar data, to a basic persistence model and to an approach based on optical flow.
no code implementations • 9 Sep 2020 • Julien Brajard, Alberto Carrassi, Marc Bocquet, Laurent Bertino
Moreover, the attractor of the system is significantly better represented by the hybrid model than by the truncated model.
no code implementations • 17 Jan 2020 • Marc Bocquet, Julien Brajard, Alberto Carrassi, Laurent Bertino
The reconstruction from observations of high-dimensional chaotic dynamics such as geophysical flows is hampered by (i) the partial and noisy observations that can realistically be obtained, (ii) the need to learn from long time series of data, and (iii) the unstable nature of the dynamics.
no code implementations • 6 Jan 2020 • Julien Brajard, Alberto Carassi, Marc Bocquet, Laurent Bertino
The output analysis is spatially complete and is used as a training set by the neural network to update the surrogate model.
no code implementations • 18 Mar 2019 • Julien Brajard, Anastase Charantonis, Jérôme Sirven
In numerical modeling of the Earth System, many processes remain unknown or ill represented (let us quote sub-grid processes, the dependence to unknown latent variables or the non-inclusion of complex dynamics in numerical models) but sometimes can be observed.
no code implementations • 26 Feb 2019 • Ibrahim Ayed, Emmanuel de Bézenac, Arthur Pajot, Julien Brajard, Patrick Gallinari
We consider the problem of forecasting complex, nonlinear space-time processes when observations provide only partial information of on the system's state.