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Data Assimilation and Optimization

The development of data assimilation methods and optimization algorithms is of particular interest for applications in the Earth sciences, aerodynamics and space dynamics.

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Data assimilation deals with the problem of estimating model parameters or model state variables by combining prior estimates and observations, together with information about their uncertainties, in a statistically optimal manner. CERFACS has well-established data assimilation activities in oceanography, atmospheric chemistry, hydrology/hydraulics and wildfires, which are conducted in close collaboration with CERFACS partners, and leading operational centres and research institutes in forecasting and retrospective analysis.

cmaes_mean_meanOptimization concerns the development of numerical algorithms for solving diverse linear and nonlinear problems. It involves studying the properties of the algorithms, such as convergence and complexity, as well as improving their performance through preconditioning techniques. CERFACS develops derivative-based and derivative-free algorithms for a variety of applications including data assimilation, Earth imaging and aerodynamics design.

Accuracy, efficiency, scalability, robustness and practicability are important considerations when designing methods for data assimilation and optimization. To develop effective methods requires a good understanding of the underlying application and problem characteristics.

 

Applications in data assimilation :fig_da_website

Hydrology/hydraulics: Water resource management and flood risk monitoring associated with the dynamics of continental waters are of first importance for public safety and financial . Flood and inundation forecasting relies on numerical modeling tools for hydraulics and hydrology combined with a wide range of observations (in situ and spaceborne). CERFACS is developing in collaboration with EDF, CNES, SCHAPI, CNRM, …, variational and ensemble data assimilation methods based on hydrologic/hydraulic solvers (among whom MASCARET and TELEMAC-2D). These implementations are part of active research activities and of their transfer to operational level.

Wildfires: Real-time prediction of wildfire spread and emissions has been identified as a valuable rsearch objective with direct applications in both fire risk management, fire emergency response and fire-induced environmental impact in the context of climate change. The predictive capability for wildfire behavior at regional scales relies on a semi-empirical modeling of a propagating front (i.e. interface between burnt and unburnt areas) at land surface, which involves biomass, topographical and meteorological data that are embedded with uncertainties. CERFACS is currently developing in collaboration with UMD and SPE an ensemble-based data assimilation system named FIREFLY, in order to sequentially estimate input parameters and the simulated fire front position when fire front position observations are available and thereby to improve the forecast performance of fire spread models.

NEWS

Young PhD day

Brigitte Yzel |  19 February 2020

Cerfacs organizes its 5th edition of the Cerfacs Doctoral Students Day on Monday, May 11, 2020. This day will be an opportunity for each doctoral student to present his or her research subject in front of an audience of Cerfacs researchers but also representatives of our industrial and academic partners, as well as selected external guests. Great novelty this year, 10 students have the privilege to participate in a specific training course such as "My thesis in 180 seconds", in order to present their research topic in French and in simple terms. The day will end with the selection of the : best poster, and the best MT180 presentation.Read more


A researcher of CERFACS guest during the France Culture radio show « La méthode scientifique » this week

superadmin |  20 January 2020

Mélanie Rochoux,  a researcher at Cerfacs working on wildfire spread modeling at the interface between CFD simulations and data science, is invited to the France Culture radio show « La méthode scientifique » next Wednesday to talk about megafires. Who are they? How are they formed? What are their impacts? How science can provide insights? The radio show is on Wednesday, January 22nd at 4:00 pm on the France Culture's channel.Read more

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