Job Description
Thesis Subject
El Niño/Southern Oscillation (ENSO) manifests itself by large-scale Sea Surface Temperature (SST) anomalies in the eastern equatorial Pacific Ocean on the order of 1–3°C and with a period of 2-7 years. These anomalies are associated with zonal displacement of the atmospheric rising branch of the Walker circulation and deep convection. Below the surface, the ocean undergoes a strong perturbation of its thermal structure with change in the eastern tropical Pacific upwelling and zonal displacements of the Indo-Pacific warm pool waters. ENSO basin-scale surface temperature fluctuations induce important changes in the tropical circulation and affects meteorological conditions globally through atmospheric teleconnections and is projected to have stronger amplitude with climate change (Vialard et al. 2025 for a review). Recently, the role of precipitation in Extreme El Niño have been recently highlighted.
Precipitation is a key parameter of the global water cycle. It is also one of the most difficult to correctly represent with models due to the number of scales that characterize the phenomena that control them. Tropical precipitations are a consequence of moist convection that is modulated at temporal scales ranging from few minutes to interannual scales and organizing at spatial scales ranging from less than a kilometer to the planetary scale. In addition to its determinant role for continental life, rainfall is thought to have other physical and chemical implications on the global climate. For example, by increasing turbulence and diluting the composition of the ocean interface and directly inject dissolved inorganic carbon, rainfall is responsible for an increase of about 7% of the global ocean carbon uptake (Parc et al. 2024). In addition, recent works showed that the interannual precipitation anomalies in the equatorial Atlantic impact the oceanic mixed layer salinity budget and are responsible for 15% of the interannual Atlantic Meridional Mode (Kataoka et al 2023). Likewise, in the equatorial Pacific they are responsible for 20% of the ENSO sea surface temperature signature (Kataoka et al. in prep.-a). In particular, they selectively enhance the development of extreme El Niño, more than doubling its occurrence. This is the RAINEE mechanism for Rainfall anomaly-induced enhancement of extreme El Niño (Kataoka et al. in prep. a and b).
The primary aims of this PhD are (i) to assess the robustness of the RAINEE mechanism in a multi-model framework and in particular its sensitivity to the model mean state, (ii) to assess its sensitivity to climate change. Further process studies of the RAINEE mechanism or relevance of this mechanism for the CO2 flux anomalies associated with ENSO will then be undertaken depending on the PhD first results. The first step of this PhD is to develop simple process-oriented metrics to evaluate the robustness of the RAINEE mechanism in Coupled Models Intercomparison Project (CMIP) models following the framework of Bellenger et al. (2014) and Planton et al. (2021). These metrics will be then be used to tackle the 2 main aims of the PhD project.
This PhD will take place in Laboratoire de Météorologie Dynamique (LMD) in Ecole Normale Supérieure (ENS) in Paris under the supervision of Hugo Bellenger (CNRS, LMD) and co-supervision of Laurent Bopp (CNRS, LMD) and Takahito Kataoka (Japan Agency for Marine-Earth Science and Technology, JAMSTEC). LMD is part of the Institute Pierre Simon Laplace (IPSL) gathering researchers in meteorology, oceanography, biogeochemistry and climate and is where the IPSL earth system model is being developed.
This PhD is part of a joint-PhD project between CNRS and the University of Tokyo. It therefore implies frequent exchanges with Japanese researchers involved in the project and visit to the Atmosphere and Ocean Research Institute (AORI) in the University of Tokyo
Your Work Environment
The thesis is funded (funding secured) by the French National Center for Scientific Research (CNRS) as part of a joint project with the University of Tokyo. The research will take place at the Laboratory of Dynamic Meteorology, École Normale Supérieure, Paris, France, within the Atmospheric Dynamics and Physics (DPA) and Ocean, Interactions, and Cycles (OIC). The student will be affiliated with the Ile-de-France Doctoral School of Environmental Sciences (ED129).
Constraints and risks
Missions to Japan, to the University of Tokyo, are planned.
Compensation and benefits
Compensation
2300 € gross monthly
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
| Offer reference | UMR8539-HUGBEL-002 |
|---|---|
| CN Section(s) / Research Area | Earth System: superficial envelopes |
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.
