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Featured researches published by Sébastien Massart.


Monthly Weather Review | 2010

On the Merits of Using a 3D-FGAT Assimilation Scheme with an Outer Loop for Atmospheric Situations Governed by Transport

Sébastien Massart; Benjamin Pajot; A. Piacentini; Olivier Pannekoucke

Abstract Three-dimensional variational data assimilation (3D-Var) with the first guess at appropriate time (FGAT) appears to be an attractive compromise between accuracy and overall computing time. It is computationally cheaper than four-dimensional (4D)-Var as the increment is not propagated back and forth in time by a model, yet the comparison between the model and the observations is still computed at the right observation time. An interesting feature of the 4D-Var is the iterative process known as the outer loop. This outer-loop approach can also be used in conjunction with 3D-FGAT. But it requires the application of the 3D-FGAT analysis increment at the beginning of the assimilation window. The pros and cons of using this unusual 3D-FGAT variant are illustrated in this paper on two applications focused on the transport, one of the main phenomena governing the atmospheric evolution. The first one is the one-dimensional advection of a passive tracer. By three representative situations, it shows the ben...


Nuclear Science and Engineering | 2007

Use of 3D-VAR and Kalman filter approaches for neutronic state and parameter estimation in nuclear reactors

Sébastien Massart; Samuel Buis; Patrick Erhard; Guillaume Gacon

Abstract In this paper, data assimilation (DA) techniques that have proven to be efficient in the fields of meteorological forecast and oceanography are applied to neutronics problems. Two applications, the techniques of which can be used to enhance optimization, are presented: three-dimensional (3-D) neutronic field interpolation in online core monitoring, and parameter estimation in code qualification procedures. First, the main bases of DA theory are shortly presented. Calibration and estimation procedures that are in use today at Electricité de France (EDF) are then briefly introduced. We also analyze the main limitations of these procedures and the potential improvements that the use of various DA techniques can provide. We present the MANARA mock-up, which computes a 3-D field interpolation and has been implemented in PALM, a DA-dedicated coupling platform developed at the Centre Européen de Recerche et de Formation Avancée en Calcul Scientifique (CERFACS). Result validation and comparison with former interpolation procedure CAMARET are also presented. Next, the principles of the KAFEINE mock-up, based on an extended Kalman filter approach, are displayed. This application covers the field of optimal parameter calibration using the in-core measures. In conclusion, these first two applications to neutronics, carried out in partnership between CERFACS and EDF Research and Development, seem very promising, especially considering the new generation of neutronic solvers that are being developed in the frame of the DESCARTES project.


Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2011

Differential influence of instruments in nuclear core activity evaluation by data assimilation

Bertrand Bouriquet; Jean-Philippe Argaud; Patrick Erhard; Sébastien Massart; Angélique Ponçot; Sophie Ricci; Olivier Thual

The global neutronic activity fields of a nuclear core can be reconstructed using data assimilation. Indeed, data assimilation allows to combine both measurements from instruments and information from a model, to evaluate the best possible neutronic activity within the core. We present and apply a specific procedure which evaluates the influence of measures by adding or removing instruments in a given measurement network (possibly empty). The study of various network configurations for the instruments in the nuclear core establishes that the influence of the instruments depends both on the independent instrumentation location and on the chosen network.


Quarterly Journal of the Royal Meteorological Society | 2008

Estimation of the local diffusion tensor and normalization for heterogeneous correlation modelling using a diffusion equation

Olivier Pannekoucke; Sébastien Massart


Atmospheric Chemistry and Physics | 2009

First steps towards the assimilation of IASI ozone data into the MOCAGE-PALM system

Sébastien Massart; Cathy Clerbaux; D. Cariolle; A. Piacentini; Solène Turquety; Juliette Hadji-Lazaro


Quarterly Journal of the Royal Meteorological Society | 2012

Importance of using ensemble estimated background error covariances for the quality of atmospheric ozone analyses

Sébastien Massart; A. Piacentini; Olivier Pannekoucke


Atmospheric Chemistry and Physics | 2010

A linear CO chemistry parameterization in a chemistry-transport model: evaluation and application to data assimilation

M. Claeyman; J.-L. Attié; L. El Amraoui; D. Cariolle; V.-H. Peuch; H. Teyssèdre; B. Josse; P. Ricaud; Sébastien Massart; A. Piacentini; Jean-Pierre Cammas; Nathaniel J. Livesey; Hugh C. Pumphrey; David P. Edwards


Journal of Power and Energy Systems | 2011

Robustness of Nuclear Core Activity Reconstruction by Data Assimilation

Bertrand Bouriquet; Jean-Philippe Argaud; Patrick Erhard; Sébastien Massart; Angélique Ponçot; Sophie Ricci; Olivier Thual


Comptes Rendus Geoscience | 2005

Vers une meilleure représentation de la distribution et de la variabilité de l'ozone atmosphérique par l'assimilation des données satellitaires

Sébastien Massart; D. Cariolle; V.-H. Peuch


Geoscientific Model Development | 2012

Impact of a time-dependent background error covariance matrix on air quality analysis

E. Jaumouillé; Sébastien Massart; A. Piacentini; D. Cariolle; V.-H. Peuch

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A. Piacentini

Centre national de la recherche scientifique

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Sophie Ricci

Centre national de la recherche scientifique

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Olivier Thual

Centre national de la recherche scientifique

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V.-H. Peuch

Centre national de la recherche scientifique

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Cathy Clerbaux

Université libre de Bruxelles

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