Missions

Context:
Forests are the second largest terrestrial carbon sink after the oceans. Preserving them is therefore an essential lever for public policy in the fight against climate change [1]. However, they are vulnerable to droughts and heatwaves, which are becoming more frequent and intense as a result of climate change [2], creating conditions conducive to forest dieback [3] and wildland fires. 2023 illustrates their vulnerability with a collapse in the carbon sink of forests and soils by a factor of 3 to 6, due in particular to the severe drought in the Amazon and major wildfires in Canada [4]. France is also experiencing forest dieback [5] and an increased risk of wildland fire, with a possible spread to the west and north of the country [6].
In this context, the objective of the ECOFEU project is to characterize forest dieback and senescence, and to study their impact on forest fire behavior, combining satellite remote sensing observations and modelling of interactions between the surface (vegetation, fire) and the atmosphere in target forest areas. The ECOFEU project is a collaboration between CECI, CNRM and CESBIO.

Description of the ECOFEU project:
The Meso-NH/BLAZE coupled fire-atmosphere model [7-9] simulates the spread of wildland fires and the fire-induced wind, thereby estimating possible scenarios (area, intensity) for a given event. However, wildland fuels are represented in an idealized manner, without accounting for vegetation dynamics (on an annual and seasonal scale), even though this can lead to an accumulation of dead fuels following normal cycles or as a result of extreme weather events, and to higher flammability of vegetation in its different vertical strata (litter, shrub layer, canopy). The ECOFEU project aims to 1) better characterize forest dieback, senescence and their impacts on the dead/living fuel partition dynamically, using remote sensing observations (time series of optical data from Sentinel-2, Landsat-8/9 and SMOS [10] optical data time series) and the SURFEX/ISBA surface model (interactions between soil, vegetation and atmosphere [11]); and 2) characterize the implications of changes in vegetation condition on fire behavior simulated by Meso-NH/BLAZE.

This postdoctorate will be carried out under the supervision of Mélanie Rochoux (CECI) and Patrick Le Moigne (CNRM).

References:
[1] Observatoire des forêts françaises, https://foret.ign.fr/themes/attenuation-effet-de-serre
[2] IPCC AR6 Climate Change 2021: The Physical Science Basis, https://www.ipcc.ch/report/ar6/wg1
[3] Vennetier, M. : Changement climatique et dépérissements forestiers : causes et conséquences, Cahier d'Études n°22, Forêt Environnement et Scoéité, CNRS (2012), https://hal.science/hal-00756083
[4] Friedlingstein et al. Global Carbon Budget 2023, Earth System Science Data, 15(12): 5301-5369 (2023)
[5] Rapport de l'Académie des Sciences, Les forêts françaises face au changement climatique (2023)
[6] Fargeon et al. Projections of fire danger under climate change over France: where do the greatest uncertainties lie?, Climatic Change, 160: 479-493 (2020)
[7] Filippi et al. Simulation of a large wildfire in a coupled fire-atmosphere model, Atmosphere, 9(218) (2018)
[8] Costes et al. Subgrid-scale fire front reconstruction for ensemble coupled atmosphere-fire simulations of the FireFlux I experiment, Fire Safety Journal 126: 103475 (2021)
[9] Couto et al. Numerical investigation of the Pedrógão Grande pyrocumulonimbus using a fire to atmosphere coupled model, Atmospheric Research, 299: 107223 (2024)
[10] Mouret et al. Toward an operational monitoring of oak dieback with multispectral satellite time series: a case study in Centre-Val de Loire Region of France, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 17: 643-659 (2024)
[11] Masson et al. The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of earth surface variables and fluxes, Geoscientific Model Development, 6: 929-960 (2013)

Activities

The work is structured in four steps:
1) Understand the forest fuel modelling in southern France (ongoing PhD thesis by Margaux Peyrot, CNRM/CECI) and adapt it to the Centre-Val de Loire region, for which dieback measurements are already available.
2) Estimate the fuel state of the shrub layer (in particular the dead and living surface load parameter) based on canopy dieback measurements acquired by CESBIO.
3) Update the BLAZE fuel models identified in step 1 that are adapted to the Centre Val de Loire region to account for possible canopy dieback.
4) Run Meso-NH/BLAZE simulations and analyze fire behavior for different levels of dieback (i.e. for different states of the shrub layer).

Skills

We are looking for a dynamic and enthusiastic young researcher to join our wildland fire modeling research group. Candidates must have a recent PhD in atmospheric sciences or fire sciences, ideally with a good understanding of how forest ecosystems work.

Candidates must have a good command of IT and numerical tools. They must be comfortable working in a team. Fluency in spoken and written English is essential.

Work Context

On the topic of wildland fires, CECI and CNRM (National Centre for Meteorological Research) have been working closely together since 2017 and the ANR FIRECASTER project. They benefit from collaborations with the operational services of Météo-France, CNES, INRAE and the National Forestry Office. As part of the ECOFEU project, these collaborations extend to CESBIO, a specialist in spatial remote sensing for forest environments.

CECI is a joint laboratory between the European Centre for Research and Advanced Training in Scientific Computing (Cerfacs), the French National Centre for Scientific Research (CNRS) and the French National Research Institute for Sustainable Development (IRD). It includes 30 to 40 researchers with strong expertise in climate and environmental models ranging from micro-scale to global scale, high-performance computing, complex simulation workflows, statistical learning, and data management. Some of the CECI's research topics focus on extreme events such as heat waves, intense precipitation and droughts, and environmental hazards such as wildfires and floods.

The Higher Education and Research Department of Météo-France comprises approximately 290 permanent staff, 150 temporary staff and 280 students. It includes a research division, in which the CNRM plays a central role under the dual supervision of Météo-France and the CNRS; a higher education division, which includes in particular the National School of Meteorology (ENM), and a partnerships and academic management division. The CNRM's Medium-Scale Meteorology Group (GMME) is structured into research teams working on non-hydrostatic modelling and cloud process parameterization; convective precipitation systems in temperate latitudes; convection and clouds in the tropics; modelling of exchange processes in the soil-plant-atmosphere continuum; characterization of continental surfaces by satellite remote sensing and data assimilation; city-atmosphere exchanges and urban climate.

The postdoctoral fellowship will take place at Météopole (42 avenue Gaspard Coriolis, 31100 Toulouse), where CECI and CNRM are located.

Additional Information

Applicants are asked to send a CV, a cover letter, and the names and e-mail addresses of two professional references through the CNRS job portal (emploi.cnrs.fr). An initial selection phase will be based on the application. Selected applicants will be contacted to an interview early November 2025.
The position will start in January 2026 (flexible).