Looking back to September 25, when Valentin Wiener successfully defended his PhD thesis entitled “The Coastal Katabatic Boundary Layer in Antarctica: from In-situ Observation to Representation in Climate Models”, supervised by Christophe Genthon, Alexis Berne, and Étienne Vignon.

Antarctica is swept by the strongest near-surface winds on Earth: the katabatic winds. Originating from the icy deserts of the continent’s interior, these dry winds descend toward the coast, where they sublimate snowfall and transport blown snow toward the ocean. These processes represent a mass loss for the Antarctic ice sheet—an immense reservoir of continental water whose evolution directly influences sea level rise in the context of global warming.

During his PhD, Valentin focused on improving our understanding of the physics of the Antarctic coastal atmospheric boundary layer, a key region where winds, turbulence, and precipitation interact. At the intersection of instrumentation and climate modeling within the project AWACA (Atmospheric WAter Cycle over Antarctica), he designed and deployed a 7-meter meteorological mast in the field, enabling unprecedented observations of turbulence and katabatic flows. These measurements are used to evaluate and calibrate the representation of these winds and precipitation processes in the LMDZ atmospheric circulation model.

His results show that surface roughness plays a major role in the intensity of simulated winds, while turbulence remains challenging to represent. In parallel, the analysis of seven years of coastal precipitation observations from a meteorological radar (MRR) reveals several limitations in the simulation of the vertical structure of the Antarctic coastal boundary layer.

This work paves the way for a better understanding and modeling of surface processes that regulate the mass balance of the Antarctic ice sheet. Congratulations to Valentin for this excellent defense, and best wishes for the future!

Learn more about his work:

• Wiener, V., Roussel, M.-L., Genthon, C., Vignon, É., Grazioli, J., and Berne, A.: A 7-year record of vertical profiles of radar measurements and precipitation estimates at Dumont d’Urville, Adélie Land, East Antarctica, Earth Syst. Sci. Data, 16, 821–836, https://doi.org/10.5194/essd-16-821-2024, 2024.
• Wiener, V., Vignon, É., Caton Harrison, T., Genthon, C., Toledo, F., Canut-Rocafort, G., Meurdesoif, Y., and Berne, A.: An extensive investigation of the ability of the ICOLMDZ model to simulate a katabatic wind event in Antarctica, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-2046, 2025.