Search Results - "Simon, Ehouarn"

Covariance Matrix Estimation for Ensemble-Based Kalman Filters with Multiple Ensembles by Gratton, Serge, Simon, Ehouarn, Titley-Peloquin, David

“…We consider the implementation of ensemble-based Kalman filters (EnKF) in the framework of ensembles of different accuracies and sizes that are smaller than…”
Get full text

Lp‐norm regularization approaches in variational data assimilation by Bernigaud, Antoine, Gratton, Serge, Lenti, Flavia, Simon, Ehouarn, Sohab, Oumaima

“…This article presents a formulation of the 4D‐Var objective function using as a penalty term a Lp‐norm with 1 < p < 2. This approach is motivated by the nature…”
Get full text

Gaussian Anamorphosis for Ensemble Kalman Filter Analysis of SAR-Derived Wet Surface Ratio Observations by Nguyen, Thanh Huy, Ricci, Sophie, Piacentini, Andrea, Simon, Ehouarn, Suquet, Raquel Rodriguez, Luque, Santiago Pena

“…Flood simulation and forecast capability have been greatly improved thanks to advances in data assimilation (DA) strategies incorporating various types of…”
Get full text

Guaranteeing the convergence of the saddle formulation for weakly constrained 4D‐Var data assimilation by Gratton, Serge, Gürol, Selime, Simon, Ehouarn, Toint, Philippe L.

“…This paper discusses convergence issues for the saddle variational formulation of the weakly constrained 4D‐Var method in data assimilation, a method whose…”
Get full text

A note on preconditioning weighted linear least‐squares, with consequences for weakly constrained variational data assimilation by Gratton, Serge, Gürol, Selime, Simon, Ehouarn, Toint, Philippe L.

“…The effect of preconditioning linear weighted least‐squares using an approximation of the model matrix is analyzed. The aim is to investigate from a…”
Get full text

Minimizing convex quadratics with variable precision conjugate gradients by Gratton, Serge, Simon, Ehouarn, Titley‐Peloquin, David, Toint, Philippe L.

“…Summary We investigate the method of conjugate gradients, exploiting inaccurate matrix‐vector products, for the solution of convex quadratic optimization…”
Get full text

A Deep Learning Approach for Estimation of the Nearshore Bathymetry by Benshila, Rachid, Thoumyre, Grégoire, Najar, Mahmoud Al, Abessolo, Grégoire, Almar, Rafael, Bergsma, Erwin, Hugonnard, Guillaume, Labracherie, Laurent, Lavie, Benjamin, Ragonneau, Tom, Simon, Ehouarn, Vieuble, Bastien, Wilson, Dennis

“…Benshila, R.; Thoumyre, G.; Al Najar, M.; Absessolo, G.; Almar, R.; Bergsma, E.; Hugonnard, G.; Labracherie, L.; Lavie, B.; Ragonneau, T.; Simon, E.; Vieuble,…”
Get full text

Neural prediction model for transition onset of a boundary layer in presence of two-dimensional surface defects by Rouviere, Adrien, Pascal, Lucas, Méry, Fabien, Simon, Ehouarn, Gratton, Serge

“…Predicting the laminar to turbulent transition is an important aspect of computational fluid dynamics because of its impact on skin friction. Traditional…”
Get full text

Application of model reduced 4D-Var to a 1D ecosystem model by Pelc, Joanna S., Simon, Ehouarn, Bertino, Laurent, El Serafy, Ghada, Heemink, Arnold W.

“…► Model reduced 4D-Var capable of combined parameter and initial condition calibration for ecosystem. ► Initial condition estimated in the reduced space, which…”
Get full text

Observation thinning in data assimilation computations by Gratton, Serge, Rincon-Camacho, Monserrat, Simon, Ehouarn, Toint, Philippe L.

“…We propose to use an observation-thinning method for the efficient numerical solution of large-scale incremental four- dimensional (4D-Var) data assimilation…”
Get full text

Dealing With Non-Gaussianity of SAR-derived Wet Surface Ratio for Flood Extent Representation Improvement by Nguyen, Thanh Huy, Ricci, Sophie, Piacentini, Andrea, Simon, Ehouarn, Suquet, Raquel Rodriguez, Luque, Santiago Peña

“…IGARSS 2023 - 2023 IEEE International Geoscience and Remote Sensing Symposium, Pasadena, CA, USA, 2023, pp. 1595-1598 Owing to advances in data assimilation,…”
Get full text

Gaussian anamorphosis extension of the DEnKF for combined state parameter estimation: Application to a 1D ocean ecosystem model by Simon, Ehouarn, Bertino, Laurent

“…We consider the problem of combined state–parameter estimations in biased nonlinear models with non-Gaussian extensions of the Deterministic Ensemble Kalman…”
Get full text

A non-linear conjugate gradient in dual space for Lp-norm regularized non-linear least squares with application in data assimilation by Bernigaud, Antoine, Gratton, Serge, Simon, Ehouarn

“…Wanting to minimize a non-linear least squares function penalized with an L p -norm, with p ∈ ( 1 , 2 ) , stemming from a 4DVar formulation of a data…”
Get full text

A non-linear conjugate gradient in dual space for $$L_p$$-norm regularized non-linear least squares with application in data assimilation by Bernigaud, Antoine, Gratton, Serge, Simon, Ehouarn

Get full text

L p ‐norm regularization approaches in variational data assimilation by Bernigaud, Antoine, Gratton, Serge, Lenti, Flavia, Simon, Ehouarn, Sohab, Oumaima

“…Abstract This article presents a formulation of the 4D‐Var objective function using as a penalty term a L p ‐norm with 1 <  p  < 2 . This approach is motivated…”
Get full text

Experiences in multiyear combined state–parameter estimation with an ecosystem model of the North Atlantic and Arctic Oceans using the Ensemble Kalman Filter by Simon, Ehouarn, Samuelsen, Annette, Bertino, Laurent, Mouysset, Sandrine

“…A sequence of one-year combined state–parameter estimation experiments has been conducted in a North Atlantic and Arctic Ocean configuration of the coupled…”
Get full text

A note on preconditioning weighted linear least squares, with consequences for weakly-constrained variational data assimilation by Gratton, Serge, Gürol, Selime, Simon, Ehouarn, Toint, Philippe L

“…Quarterly Journal of the Royal Meteorological Society, vol. 144(172), pp. 934--940, 2018 The effect of preconditioning linear weighted least-squares using an…”
Get full text

An algorithm for the minimization of nonsmooth nonconvex functions using inexact evaluations and its worst-case complexity by Gratton, S., Simon, E., Toint, Ph. L.

“…An adaptive regularization algorithm using inexact function and derivatives evaluations is proposed for the solution of composite nonsmooth nonconvex…”
Get full text

Minimizing convex quadratics with variable precision conjugate gradients by Gratton, Serge, Simon, Ehouarn, Titley-Peloquin, David, Toint, Philippe

“…We investigate the method of conjugate gradients, exploiting inac-curate matrix-vector products, for the solution of convex quadratic op-timization problems…”
Get full text

Online tuning of ocean biogeochemical model parameters using ensemble estimation techniques: Application to a one-dimensional model in the North Atlantic by Gharamti, M.E., Samuelsen, A., Bertino, L., Simon, E., Korosov, A., Daewel, U.

“…Given the recent focus on developing new data assimilation systems for biological models, we present in this study the application of a newly developed…”
Get full text