Patrick Laloyaux

Senior Scientist
Research Department, Earth System Assimilation Section, Data Assimilation Methodology Group

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Patrick Laloyaux leads the research and the development on coupled atmosphere-ocean assimilation which initially targets the production of global 20th century reanalyses, reconstructing the earth's past weather from historical observations. This work is part of the ERA-CLIM2 project funded by the European Commission under the 7th Framework Programme.

He also investigates the benefits of the coupled atmosphere-ocean assimilation for medium-range weather forecasting. This approach has the potential to produce a more consistent coupled ocean-atmosphere analysis, to improve the use of near-surface measurements and to reduce initialisation shocks in coupled forecasts.

More information:

Professional interests: 
  • Coupled atmosphere-ocean assimilation
  • Earth system reanalysis
  • Variational and ensemble assimilation methods
  • Climate change
  • Software architecture
  • Numerical optimisation
Career background: 

Trained as an applied mathematician, he has expertise in optimisation methods for variational problems and in ensemble Kalman filters. He obtained his PhD from the University of Namur (Belgium) conducted in partnership with the European Centre for Research and Advanced Training in Scientific Computation (CERFACS, France). During his PhD, he developed new preconditioning and gradient-free techniques for solving variational problems. He was also a teaching assistant giving tutorials (220 hours/year) to undergraduate and graduate students in programming, scientific computation and numerical optimization.


Peer-reviewed publications

A coupled data assimilation system for climate reanalysis

Quarterly Journal of the Royal Meteorological Society,142:65-78, 2016

Authors: P. Laloyaux, M. Balmaseda, D. Dee, K. Mogensen, P. Janssen

Impact of scatterometer surface wind data in the ECMWF coupled assimilation system

Monthly Weather Review, 2016

Authors: P. Laloyaux, J-N Thépaut, D. Dee

Origin and impact of initialisation shocks in coupled atmosphere-ocean forecasts

Monthly Weather Review, 2016

Authors: D. Mulholland, P. Laloyaux, K. Haines, M. Balmaseda

Derivative-free optimization for large-scale nonlinear data assimilation problems

Quarterly Journal of the Royal Meteorological Society, 140:943-957, 2014

Authors: S. Gratton, P. Laloyaux and A. Sartenaer

A reduced and limited-memory preconditioned approach for the 4D-Var data-assimilation problem

Quarterly Journal of the Royal Meteorological Society, 137(452-466), 2011

Authors : S. Gratton, P. Laloyaux, A. Sartenaer and J. Tshimanga

Other publications

CERA-20C production has started

ECMWF Newsletter, 146, 2016

Authors: P. Laloyaux

Forty years of improving global forecast skill

ECMWF Newsletter, 145, 2015

Authors: P. Laloyaux and L. Bengtsson

CERA: A coupled data assimilation system for climate reanalysis

ECMWF Newsletter, 144, 2015

Authors: P. Laloyaux and D. Dee


thumbnail photo of Patrick Laloyaux
Contact Details:
patrick . laloyauxecmwf . int