Scientific Computing Engineer (M/F) – Coupled Physical–Biogeochemical Modelling in the Mediterranean

Job Description

Missions

Project background
This recruitment is part of the Priority Research Programme (PPR) Ocean & Climate, jointly led by CNRS and Ifremer. The programme was established by the French government for a seven-year period (2021–2028) to address research challenges related both to advances in climate and ecological knowledge and to issues concerning the blue economy, law, geostrategy, integrated socio-ecosystem management, and societal well-being.
More specifically, this recruitment is carried out within the framework of the Riomar project, which aims to improve understanding of the impact of climate change and anthropogenic pressures on the functioning of marine coastal ecosystems in the northwestern Mediterranean during the 21st century. One of the five study areas investigated in the project is the Gulf of Lion shelf.
The Gulf of Lion is an oceanic margin characterized by high primary productivity within an oligotrophic sea (Bosc et al., 2004). This high productivity results from riverine nutrient inputs, winter mixing between surface waters and underlying waters (Many et al., 2021), and wind-induced upwelling processes (Fraysse et al., 2014), which promote the upward transport of nutrients into the euphotic layer. The Gulf of Lion is also influenced by the Northern Current, a branch of the Mediterranean general circulation (Petrenko et al., 2008).
The Mediterranean Sea is one of the regions most vulnerable to climate change and is subject to strong anthropogenic pressures (Durrieu de Madron et al., 2011). The main questions addressed are: what are and what will be the impacts of changes in temperature, stratification, and river inputs (discharge and nutrient concentrations) on the Gulf of Lion shelf during the 21st century with regard to (1) the functioning of the planktonic ecosystem, (2) dissolved oxygen dynamics, and (3) carbonate system dynamics? What is the impact of the increasing frequency and intensity of extreme events on these dynamics?
The project aims to implement realistic and climate simulations at high resolution (finer than 400 m), using the Symphonie circulation model (Marsaleix et al., 2008) and the Eco3M-S biogeochemical model (Ulses et al., 2023), both developed at OMP. The project will be conducted within the development team of these hydrodynamic and biogeochemical models, which has extensive expertise in modelling the Gulf of Lion.

Main duties
The proposed position aims to investigate the impact of climate change and anthropogenic modifications of river inputs on the functioning of the planktonic ecosystem and on biogeochemical cycles in the Mediterranean.
The work will involve assessing changes in phytoplankton growth, carbon cycling (primary production, carbon export to the seafloor, and air-sea exchanges), and dissolved oxygen dynamics (ventilation and air-sea exchanges). To this end, regional high-resolution coupled physical-biogeochemical simulations will be implemented and used for the historical period 1990–2020 and the future period 2020–2100 based on the SSP5-8.5 scenario, at two spatial scales: (1) the entire Mediterranean basin at a resolution of 6–8 km, and (2) the northwestern region at a resolution finer than 450 m (for which only the periods 2030–2050 and 2080–2100 will be simulated). Sensitivity experiments to nutrient inputs will also be carried out. Historical simulations will be compared with observations for validation and improvement purposes.
Coupled Symphonie/MUSTANG sediment transport simulations may also be developed in order to assess the impact of sediment and nutrient resuspension on biogeochemical cycles.

Activity

The work proposed within the framework of this position will consist of:

- Implementing a historical run and the SSP5-8.5 scenario using the coupled physical-biogeochemical models NEMO-Eco3MS and Symphonie-Eco3MS. Historical runs will be carried out for the period 1990–2015 at the two spatial scales of the Mediterranean basin (low-resolution model) and the northwestern basin (high-resolution model). The SSP5-8.5 scenario will be implemented for the period 2015–2100 at the Mediterranean basin scale, and for the periods 2030–2050 and 2080–2100 at the northwestern basin scale.
- Evaluating the results of the historical simulation through comparisons with in situ and satellite observations. Biases will be quantified through comparison with realistic simulations. Sensitivity tests may be performed on the parameterizations (e.g. primary production) and parameters (e.g. sinking velocity, remineralization rate) of the biogeochemical model.
- Assessing the impacts of climate change on biogeochemical fluxes and combined extreme events through the analysis of trends and differences between future periods and the historical period.
- Implementing a sediment transport model for the Gulf of Lion. Depending on the results obtained from the first two tasks, a sediment transport simulation will be developed for the high-resolution configuration over the period 1990–2023, using the coupled Symphonie-MUSTANG model.

Your Profil

Skills

- Master's degree (MSc, 5-year university degree) or Engineering degree
- Experience in oceanography would be appreciated
- Experience in numerical modelling and data processing
- Programming skills and proficiency with analysis tools (Fortran, Python, Matlab, or similar)
- Ability to work collaboratively
- Autonomy and organizational skills

Your Work Environment

LEGOS is a Joint Research Unit (Unité Mixte de Recherche) involving the University of Toulouse, CNES, CNRS-INSU, and IRD, and comprises approximately 130 staff members. It conducts multidisciplinary research on the Earth's environmental system, drawing on expertise in physical oceanography, marine geochemistry and biogeochemistry, hydrology, and glaciology.

The engineer will join the ECOLA team at LEGOS. This team has strong expertise in high-resolution coupled physical, biogeochemical, and sediment transport modelling. Weekly meetings will be organized to discuss the progress of the project.

Compensation and benefits

Compensation

between 2 496.98 € and 3 706.14 €

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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