Missions

Oceanic convection is still poorly understood, while it is one of the main drivers of ocean dynamics. Convection can be penetrative (entraining water beneath the turbulent layer) or non-penetrative. While it is relatively straightforward to formulate conceptual parameterisations of non-penetrating convection in idealised contexts, it remains difficult to extend the formalism to realistic contexts of penetrating convection, even for the latest ocean models. In 2024, we carried out a series of laboratory experiments on the Coriolis platform and are now working to complement this data set with numerical simulations to explore many types of surface forcing and initial conditions. The aim of the postdoc is to combine these observations and model outputs with a robust theoretical framework to build a coherent parameterisation of ocean convection. In autumn 2025, we will conduct a second series of experiments on the Coriolis platform.
The successful candidate will be hosted by the LEGI laboratory (1209-1211 rue de la piscine, 38400 GRENOBLE France) within the MEIGE team and will work in close collaboration with ME Negretti, J Sommeria and B Deremble from the IGE laboratory.
The researcher will analyse data to assess the characteristics of turbulence and energy transfer, and will use tools to diagnose turbulent mixing. Regular meetings with researchers from the project consortium (IGE laboratory and INRIA laboratory in Grenoble) will enable experimental data to be compared with numerical data. The data and tools produced as part of this project will be used to build a convection parameterisation for ocean models.

Activities

- Post-processing and analysis of the data obtained in the June-July 2024 measurement campaign. Coordination needs to be organised with the subject of a PhD student's current thesis (Max Coppin).
-The researcher will focus on the innovative data analysis methods developed at the INRIA laboratory in Grenoble, which is a partner in the project. This should make it possible to identify the structure of convective plumes and associated eddies at the source of the mixing process,
- Participation in the writing of an article on the results of the 2024 campaign,
- Preparation and implementation of a new experimental campaign to be carried out in 2025,
- Analysis and publication of the data from this new campaign.

Skills

The successful candidate should be able to master several techniques, such as particle image velocimetry (PIV), laser-induced fluorescence (LIF), image pre- and post-processing, data analysis and statistics (Python/MATLAB).
Skills required:
- Sound knowledge of fluid mechanics, data processing and theoretical and numerical tools in physics is essential.
- Proven ability to write international scientific articles is required.
- Curiosity, autonomy and a willingness to develop new skills are also required.

Work Context

The Laboratoire des Écoulements Géophysiques et Industriels (LEGI) is a joint research unit (UMR 5519) of the CNRS, Grenoble INP and the Université Grenoble-Alpes (UGA). LEGI carries out a wide range of activities, with a common core of skills: research into fluid mechanics and transfers. The successful candidate will join the MEIGE team, which specialises in geophysical turbulence. The MEIGE team's research in this field is fundamental and focuses on the effects of rotation and stratification on geophysical turbulence and on boundary layer processes in the presence of density stratification (atmospheric or oceanic boundary layers). LEGI's Coriolis platform is the only experimental facility in the world where the combined effects of turbulence, stratification and rotation can be studied in a fully turbulent regime.

Constraints and risks

Use of lasers for the experiments.