02/12/2025: – PhD defense of Niels Dutrievoz directed by Cécile AGOSTA
L’objectif de cette thèse est d’améliorer la compréhension du cycle de l’eau atmosphérique en Antarctique en utilisant les isotopes comme traceurs des processus de couche limite et de la dynamique à grande échelle, via une approche combinant observations isotopiques dans la The objective of this thesis is to improve understanding of the atmospheric water cycle in Antarctica by using isotopes as tracers of boundary layer processes and large-scale dynamics, through an approach combining isotopic observations in vapor and modeling with LMDZiso (atmospheric component of the IPSL-CM climate model).
The first part evaluates the model in Antarctica and analyzes the processes controlling the isotopic variability of vapor during summer daily cycles. The results show that these cycles are dominated by air-snow exchanges (sublimation and condensation) on the continental shelf (Concordia), as well as by katabatic advection in coastal areas (Dumont d’Urville). Analysis of an atmospheric river event (December 2018) reveals that the isotopic signal of vapor in the boundary layer cannot be explained solely by synoptic transport and requires consideration of local processes.
The second part focuses on improving snow-vapor isotopic interactions in LMDZ6iso. The introduction of a fractionation scheme during sublimation, a similar formulation for the condensation flux, and an active snow layer approximately 1 cm thick significantly improves the representation of the diurnal cycle of vapor isotopes. Finally, analysis of virtual snow cores reveals the strong isotopic fingerprint in the snow of an atmospheric river event (March 2022), opening up prospects for the study of past extreme events in glacial archives.
Article 1 : https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2590/
Article 2 : https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024JD042073