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Number of documents

43

CV de Julien Brajard


My work is in the field of remote sensing, inverse modelling, machine learning and data assimilation.

The objective is to propose new methodologies in order to extract knowledge from data and physical systems, 

more specifically in oceanography.

 

Those methodologies were apply to estimate and forecast key variables and their associated uncertainty in the ocean such as 

phytoplankton and surface currents. The methodologies developed were

using remote sensing data (satellite sensors).

 

Key words : Machine learning, statistical methods, remotesensing, oceanography, computer science


Journal articles21 documents

  • Jules Guillot, Guillaume Koenig, Kadi Minbashian, Emmanuel Frénod, Héléne Flourent, et al.. Partial differential equations for oceanic artificial intelligence. ESAIM: Proceedings and Surveys, EDP Sciences, 2021, 70, pp.137-146. ⟨10.1051/proc/202107009⟩. ⟨hal-03265258⟩
  • Maike Sonnewald, Redouane Lguensat, Daniel C. Jones, Peter D. Dueben, Julien Brajard, et al.. Bridging observations, theory and numerical simulation of the ocean using machine learning. Environmental Research Letters, IOP Publishing, 2021, 16 (7), pp.073008. ⟨10.1088/1748-9326/ac0eb0⟩. ⟨hal-03311328⟩
  • Georges Baaklini, Leila Issa, Milad Fakhri, Julien Brajard, Gina Fifani, et al.. Blending drifters and altimetric data to estimate surface currents: Application in the Levantine Mediterranean and objective validation with different data types. Ocean Modelling, Elsevier, 2021, 166, pp.101850. ⟨10.1016/j.ocemod.2021.101850⟩. ⟨hal-03329128⟩
  • Vincent Bouget, Dominique Béréziat, Julien Brajard, Anastase Alexandre Charantonis, Arthur Filoche. Fusion of Rain Radar Images and Wind Forecasts in a Deep Learning Model Applied to Rain Nowcasting. Remote Sensing, MDPI, 2021, 13 (2), pp.246. ⟨10.3390/rs13020246⟩. ⟨hal-03112093⟩
  • Khalil Yala, N'Dèye Niang, Julien Brajard, Carlos Mejia, Mory Ouattara, et al.. Estimation of phytoplankton pigments from ocean-color satellite observations in the Senegalo–Mauritanian region by using an advanced neural classifier. Ocean Science, European Geosciences Union, 2020, 16 (2), pp.513-533. ⟨10.5194/os-16-513-2020⟩. ⟨hal-02904148⟩
  • Julien Brajard, Alberto Carrassi, Marc Bocquet, Laurent Bertino. Combining data assimilation and machine learning to emulate a dynamical model from sparse and noisy observations: A case study with the Lorenz 96 model. Journal of computational science, Elsevier, 2020, 44, pp.101171. ⟨10.1016/j.jocs.2020.101171⟩. ⟨hal-03147335⟩
  • Éric Machu, Xavier Capet, Philippe Estrade, Siny Ndoye, Julien Brajard, et al.. First Evidence of Anoxia and Nitrogen Loss in the Southern Canary Upwelling System. Geophysical Research Letters, American Geophysical Union, 2019, 46 (5), pp.2619-2627. ⟨10.1029/2018GL079622⟩. ⟨hal-02067752⟩
  • Marc Bocquet, Julien Brajard, Alberto Carrassi, Laurent Bertino. Data assimilation as a learning tool to infer ordinary differential equation representations of dynamical models. Nonlinear Processes in Geophysics, European Geosciences Union (EGU), 2019, 26 (3), pp.143-162. ⟨10.5194/npg-26-143-2019⟩. ⟨hal-02517929⟩
  • Hector-Simon Benavidès Pinjosovsky, Sylvie Thiria, Catherine Ottlé, Julien Brajard, Fouad Badran, et al.. Variational assimilation of land surface temperature within the ORCHIDEE Land Surface Model Version 1.2.6. Geoscientific Model Development, European Geosciences Union, 2017, 10 (1), pp.85-104. ⟨10.5194/gmd-10-85-2017⟩. ⟨hal-01492602⟩
  • K.R. Mangalaa, Damien Cardinal, Julien Brajard, D.B. Rao, N.S. Sarma, et al.. Silicon cycle in Indian estuaries and its control by biogeochemical and anthropogenic processes. Continental Shelf Research, Elsevier, 2017, 148, pp.64-88. ⟨10.1016/j.csr.2017.08.011⟩. ⟨hal-01651900⟩
  • Leila Issa, Julien Brajard, Milad Fakhri, Daniel Hayes, Laurent Mortier, et al.. Modelling surface currents in the Eastern Levantine Mediterranean using surface drifters and satellite altimetry. Ocean Modelling, Elsevier, 2016, 104, pp.1-14. ⟨10.1016/j.ocemod.2016.05.006⟩. ⟨hal-01357669⟩
  • Pacôme Eberhart, Julien Brajard, Pierre Fortin, Fabienne Jézéquel. High Performance Numerical Validation using Stochastic Arithmetic . Reliable Computing, Springer Verlag, 2015, 21, pp.35-52. ⟨hal-01254446⟩
  • Ousmane Farikou, Salam Sawadogo, Awa Niang, Daouda Diouf, Julien Brajard, et al.. Inferring the seasonal evolution of phytoplankton groups in the Senegalo-Mauritanian upwelling region from satellite ocean-color spectral measurements. Journal of Geophysical Research. Oceans, Wiley-Blackwell, 2015, 120 (9), pp.6581--6601. ⟨10.1002/2015JC010738⟩. ⟨hal-01507522⟩
  • Ousmane Farikou, Salam Sawadogo, Niang Awa, Julien Brajard, Carlos Mejia. Multivariate analysis of the Senegalo-Mauritanien area by merging satellite remote sensing ocean color and SST observations. Journal of Research in Environmental and Earth Sciences, Knowledge Journals 2013, ⟨10.19026/RJEES.5.5733⟩. ⟨hal-02079429⟩
  • Daouda Diouf, Awa Niang, Julien Brajard, Michel Crépon, Sylvie Thiria. Retrieving aerosol characteristics and sea-surface chlorophyll from satellite ocean color multi-spectral sensors using a neural-variational method. Remote Sensing of Environment, Elsevier, 2013, 130, pp.74 - 86. ⟨10.1016/j.rse.2012.11.002⟩. ⟨hal-01495282⟩
  • Julien Brajard, Richard Santer, Michel Crépon, Sylvie Thiria. Atmospheric correction of MERIS data for case-2 waters using a neuro-variational inversion. Remote Sensing of Environment, Elsevier, 2012, 126, pp.51 - 61. ⟨10.1016/j.rse.2012.07.004⟩. ⟨hal-01495015⟩
  • Fouad Badran, Mohamed Berrada, Julien Brajard, Michel Crépon, Charles Sorror, et al.. Inversion of satellite ocean colour imagery and geoacoustic characterization of seabed properties: Variational data inversion using a semi-automatic adjoint approach. Journal of Marine Systems, Elsevier, 2008, 69 (1-2), pp.126--136. ⟨10.1016/j.jmarsys.2007.02.018⟩. ⟨hal-01507523⟩
  • Julien Brajard, Cyril Moulin, Sylvie Thiria. Atmospheric correction of SeaWiFS ocean color imagery in the presence of absorbing aerosols off the Indian coast using a neuro-variational method. Geophysical Research Letters, American Geophysical Union, 2008, 35, pp.20604. ⟨10.1029/2008GL035179⟩. ⟨hal-00752788⟩
  • Julien Brajard, Awa Niang, Salam Sawadogo, Frank Fell, Richard Santer, et al.. Estimating aerosol parameters above the ocean from MERIS observations using topological maps. International Journal of Remote Sensing, Taylor & Francis, 2007, 28 (3-4), pp.781--795. ⟨10.1080/01431160600821101⟩. ⟨hal-01507524⟩
  • Julien Brajard, Cédric Jamet, Cyril Moulin, Sylvie Thiria. Validation of a neuro-variational inversion of ocean colour images. Advances in Space Research, Elsevier, 2006, 38 (10), pp.2169-2175. ⟨10.1016/j.asr.2006.03.039⟩. ⟨hal-00750296⟩
  • Julien Brajard, Cédric Jamet, Cyril Moulin, Sylvie Thiria. Use of a neuro-variational inversion for retrieving oceanic and atmospheric constituents from satellite ocean colour sensor: Application to absorbing aerosols. Neural Networks, Elsevier, 2006, 19, pp.178-185. ⟨10.1016/j.neunet.2006.01.015⟩. ⟨hal-00122477⟩

Conference papers18 documents

  • Arthur Filoche, Dominique Béréziat, Julien Brajard, Anastase Alexandre Charantonis. Variational assimilation of Geophysical images leveraging deep learning tools. ORASIS 2021, Centre National de la Recherche Scientifique [CNRS], Sep 2021, Saint Ferréol, France. ⟨hal-03339674⟩
  • Georges Baaklini, Leila Issa, Julien Brajard, Milad Fakhri, Milena Menna, et al.. Mesoscale Activity in the Eastern Mediterranean: Blending Altimetry with in situ observations. EGU General assembly 2020, May 2020, virtual, Zimbabwe. ⟨10.5194/egusphere-egu2020-20407⟩. ⟨hal-03082863⟩
  • Arthur Filoche, Julien Brajard, Anastase Alexandre Charantonis, Dominique Béréziat. Completing physics-based models by learning hidden dynamics through data assimilation. NeurIPS 2020, workshop AI4Earth, Dec 2020, Vancouver (virtual), Canada. ⟨hal-03004938⟩
  • Julien Brajard, Anastase Alexandre Charantonis, Jérôme Sirven. Can a neural network learn a numerical model ?. EGU General Assembly, Apr 2018, Vienne, Austria. ⟨hal-02067473⟩
  • Pacôme Eberhart, Baptiste Landreau, Julien Brajard, Pierre Fortin, Fabienne Jézéquel. Improving CADNA Performance on GPUs. 2018 IEEE International Parallel and Distributed Processing Symposium Workshops (IPDPSW), May 2018, Vancouver, Canada. pp.1016-1025, ⟨10.1109/IPDPSW.2018.00156⟩. ⟨hal-01858537⟩
  • Julien Brajard, Anastase Alexandre Charantonis, Frédéric Jourdin. Predicting Ocean Dynamics through Machine Learning: Application on Sea-Surface Suspended Particulate Mater. American Meteorological Society Annual Meeting 2017, American Meteorological Society, Jan 2017, Seattle, United States. ⟨hal-01477182⟩
  • Yala Khalil, Julien Brajard, Michel Crépon, Éric Machu, Ndèye Niang. Determination of phytoplankton groups from space: application to senegalo-mauritanean upwelling. EGU General Assembly, 2016, Vienne, Austria. pp.15098. ⟨hal-01507521⟩
  • Pacôme Eberhart, Julien Brajard, Pierre Fortin, Fabienne Jézéquel. Estimation of Round-off Errors in OpenMP Codes. IWOMP 2016 - 12th International Workshop on OpenMP, Riken AICS, Oct 2016, Nara, Japan. pp.3-16, ⟨10.1007/978-3-319-45550-1_1⟩. ⟨hal-01380131⟩
  • Julien Brajard, Jérôme Sirven, Olivier Talagrand. Ensemble variational data assimilation with a shallow-water model: preliminary results. EGU General Assembly, Apr 2016, Vienne, Austria. pp.14836. ⟨hal-01507519⟩
  • Pacôme Eberhart, Julien Brajard, Pierre Fortin, Fabienne Jézéquel. Towards high performance stochastic arithmetic. 16th international symposium on Scientific Computing, Computer Arithmetic and Validated Numerics (SCAN 2014), Sep 2014, Würzburg, Germany. pp.47-48. ⟨hal-01217244⟩
  • Ymane Taoufiq, Ousmane Farikou, Séverine Alvain, Julien Brajard, Michel Crépon, et al.. Determination of phytoplankton groups from ocean color spectral measurements in the Senegalo-Mauritanian upwelling. Ocean Optics, The Oceanography Society (TOS), Oct 2014, Portland, Maine, United States. ⟨hal-01191676⟩
  • Julien Brajard, Pei Li, Fabienne Jézéquel, Hector-Simon Benavidès Pinjosovsky, Sylvie Thiria. Numerical Validation of Data Assimilation Codes Generated by the YAO Software. SIAM Annual Meeting, Jul 2013, San Diego, California, United States. ⟨hal-01216453⟩
  • Julien Brajard, Daouda Diouf, Hector-Simon Benavidès Pinjosovsky, Michel Crépon, Richard Santer, et al.. Neuro-Variational Inversion Applied to Ocean Color Remote Sensing. American Meteorological Society Annual Meeting, 2012, La Nouvelle Orléans, United States. ⟨hal-00750316⟩
  • Anastase Alexandre Charantonis, Sylvie Thiria, Cyril Moulin, Julien Brajard. Inversion of sea surface data to retrieve the vertical distribution of phytoplankton using a statistical methodology. Congrès European Geophysical Union, 2011, Vienne, Austria. ⟨hal-00750248⟩
  • Mohamed Berrada, Julien Brajard, Charles Deltel, Michel Crépon, Fouad Badran, et al.. Variational data assimilation in NEMO using YAO. Congrès European Geophysical Union, 2011, Vienne, Austria. ⟨hal-00750253⟩
  • Daouda Diouf, Sylvie Thiria, Awa Niang, Julien Brajard, Michel Crépon. Retrieving aerosol characteristics from satellite ocean color multi-spectral sensors using a neural-variational method. NCTA 2011 : NCTA- International Conference on Neural Computation Theory and Applications, 2011, Paris, France. ⟨hal-00750307⟩
  • Anastase Alexandre Charantonis, Julien Brajard, Cyril Moulin, Fouad Badran, Sylvie Thiria. Inverse method for the retrieval of ocean vertical profiles using self-organizing maps and hidden Markov models - Application on Ocean Colour Satellite Image Inversion. NCTA 2011 : NCTA- International Conference on Neural Computation Theory and Applications, 2011, Paris, France. ⟨hal-00750300⟩
  • Daouda Diouf, Julien Brajard, Awa Niang, Salam Sawadogo, Michel Crépon, et al.. Atmospheric correction and chlorophyll-a restitution in presence of Saharan dusts. Congrès European Geophysical Union, 2011, Vienne, Austria. ⟨hal-00750241⟩

Poster communications1 document

  • Leila Issa, Julien Brajard, Milad Fakhri, Laurent Mortier, Pierre-Marie Poulain. Modeling Surface Currents in the Eastern Levantine Mediterranean. EGU General Assembly Conference, Apr 2015, Vienna, Austria. 17, pp.8888. ⟨hal-01191755⟩

Book sections1 document

  • Daouda Diouf, Awa Niang, Julien Brajard, Salam Sawadogo, Michel Crépon, et al.. Spatial Distribution of Aerosol Optical Thickness Retrieved from SeaWiFS Images by a Neural Network Inversion over the West African Coast. Aerosols-Science and Case Studies, InTech, 2016, 978-953-51-2843-4. ⟨10.5772/65874⟩. ⟨hal-01507520⟩

Preprints, Working Papers, ...2 documents

  • Ibrahim Ayed, Emmanuel de Bézenac, Arthur Pajot, Julien Brajard, Patrick Gallinari. Learning Dynamical Systems from Partial Observations. 2019. ⟨hal-02418376⟩
  • Luigi Nardi, Julien Brajard, Sylvie Thiria, Fouad Badran, Pierre Fortin. Automatic generation of parallel and coherent code using the YAO variational data assimilation framework. 2016. ⟨hal-00783328v2⟩