Expert en calcul scientifique

The position is primarily based at the Laboratoire des Sciences du Climat et de l’Environnement (LSCE) on the Plateau de Saclay. Frequent visits to the Laboratoire de Météorologie Dynamique (LMD) in Jussieu are expected.

Mission : Water isotopes (Oxygen 18, Deuterium) in the ocean/atmosphere/biosphere/cryosphere serve as a powerful hydrologic tracer and as an essential proxy to interpret paleoclimatic changes across time scales. They constitute an essential tool to compare field data observations with model simulations as significant advances have been made in earth system models (ESMs) in the last decades to simulate the complete cycle of water isotopes. Although they are or have once been implemented separately in all components (atmosphere, ocean and vegetation/land surface) of the IPSL ESM, a fully-coupled, isotope-enabled version of the IPSL ESM is still lacking.

To overcome this issue, the IPSL is funding an 18-month postdoc position to re-implement water isotopes in the vegetation and land surface model, as part of a bigger initiative to perennially include water isotopes in each component of the IPSL ESM as well as develop a fully-coupled, isotope-enabled version of the ESM. The position may be renewable contingent upon satisfactory performance.

Activités principales :

The successful candidate will be in charge of the reimplementation of water isotopes in the ORCHIDEE land surface and vegetation model, with a focus on the perennial aspect of the implementation. The main task will consist in implementing the transfer of water isotopes in the physically-based 11-layer soil hydrology scheme (describing vertical water diffusion), the enrichment of water isotopes in the leaf and the overall coupling between the different water pools described in ORCHIDEE.

In a second time, the candidate is expected to perform the coupling between ORCHIDEE and the LMDZ atmosphere model to create an essential block of the fully coupled, isotope-enabled, IPSL earth system model.

This work will at both stages be validated against modern water isotope measurements in vegetation, soils and the atmosphere.

Although the core of the initial work is the implementation of water isotopes in ORCHIDEE, scientific applications of the isotope-enabled ORCHIDEE and ORCHIDEE-LMDZ models are expected, pending appropriate progress, resulting in authorship or co-authorship of several scientific papers, notably a reference paper on water isotopes in ORCHIDEE and its validation. Further scientific applications may include hydrological and/or paleo-climate studies.

The candidate will primarily be based at LSCE and will benefit from the expertise of the lab on the ORCHIDEE model and in the coupling between the different components of the IPSL ESM. Frequent visits to LMD will be necessary to ensure appropriate progress. Close interactions with scientists from different IPSL thematic structures will also be pivotal.

Savoir-faire :

- PhD in earth system sciences or computer sciences

- Experience in numerical modelling is necessary; experience with land surface models is desirable

- Good programming skills

- Knowledge of MPI/OpenMP programming is an asset

- Knowledge of the ORCHIDEE model is an asset

- Knowledge of the water isotope cycle in the atmosphere/biosphere is an asset

- Knowledge of the vegetation and soil physics is an asset

Savoir-être :

- Good communication and teamworking skills to ensure appropriate interactions with the different labs are essential