Postdoctoral position OT-23168
Postdoctoral Position F/M Multifractal stochastic modeling and downscaling in micro-meteorology
35044
INRAE presentation
The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.
Work environment, missions and activities
The DEDECHAO (DEscente D’Échelle par CHAOs multiplicatif Gaussien) project explores a novel approach to downscaling in micro-meteorology, framed as a Bayesian inverse problem. The goal is to estimate high-resolution (10m) wind speeds based on low-resolution (10km) data, probabilistic simulations, and local measurement assimilation. This method will leverage the Gaussian Multiplicative Chaos (GMC) [1] as a generative model for wind fields, incorporating intermittency in turbulence [1,2] to capture extreme variations in wind speed at small scales. The project has significant implications for agroecological practices, such as improving the dispersion modeling of volatile organic compounds (VOCs) and spores in pest control and epidemic surveillance.
The postdoctoral fellow will contribute to the development of a stochastic, data-driven model capable of generating high-resolution 3D+1 wind velocity fields. The research will focus on coupling coarse-grid mechanistic simulations with high-frequency local data assimilation using ensemble Kalman filtering techniques. A key challenge will be to reproduce the intermittent, multifractal nature of turbulent flows, crucial for accurate dispersion models in agroecology.
Adapt a wavelet-based GMC code for generating intermittent 3D+1 wind velocity fields [3].
Couple GMC with mechanistic simulations through scale symmetries and stochastic transport
Integrate large-scale meteorological data with in-situ measurements through data assimilation techniques.
Validate the model's predictions against high-resolution simulation outputs (from PALM software).
Prepare research papers and present results at scientific conferences.
REFERENCES
B. Castaing, Y. Gagne and E.J. Hopfinger, Velocity probability density functions of high Reynolds number turbulence, Physica D, 46 (1990) 177-200.
L. Chevillard, B. Castaing, A. Arneodo, E. Leveque, J.-F. Pinton and S.G. Roux, A phenomenological theory of Eulerian and Lagrangian velocity fluctuations in turbulent flows, C.R. Physique, 13 (2012), 899-928.
C. Granero-Belinchon, S.G. Roux and N.B. Garnier, Multiscale and anisotropic characterization of images based on complexity: an application to turbulence. Physica D, 459 (2024), 134027.
Training and skills
PhD in applied mathematics, fluid dynamics, atmospheric sciences, or related fields.
Strong expertise in stochastic modeling, turbulence, and numerical simulations.
Experience with data assimilation methods (e.g., ensemble Kalman filtering) and Bayesian inference.
Familiarity with large-scale atmospheric simulations and downscaling techniques.
Proficiency in Python
Experience with high-performance computing is a plus.
INRAE's life quality
By joining our teams, you benefit from (depending on the type of contract and its duration):
- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.
How to apply
I send my CV and my motivation letter
All persons employed by or hosted at INRAE, a public research establishment, are subject to the Civil Service Code, particularly with regard to the obligation of neutrality and respect for the principle of secularism. In carrying out their functions, whether or not they are in contact with the public, they must not express their religious, philosophical or political convictions through their behaviour or by what they wear. > Find out more: fonction publique.gouv.fr website (in French)