CNFGG thesis prize awarded to Arthur Avenas
French National Committee for Geodesy and Geophysics (CNFGG) thesis prize in the Geophysics category awarded to :
Arthur Avenas, UMR LOPS, for his thesis entitled ‘Tropical cyclone dynamics revealed by satellite observations of surface wind speed: the major contribution of the surface wind structure near the core’, prepared at the École nationale supérieure Mines-Télécom Atlantique Bretagne Pays de Loire and defended on 28 March 2024.
‘Tropical cyclone dynamics revealed by satellite observations of surface wind speeds: the major contribution of the surface wind structure near the core’.
Despite advances in the prediction of tropical cyclone tracks and wind speeds in the outer region, the numerical representation of the strongest winds associated with the most intense events remains an open question, mainly due to the small size of the cyclone core and the difficulty in understanding and resolving the turbulent exchanges between the ocean and atmosphere. Observational limitations have long hampered accurate measurements of the ocean surface near the core region in extreme wind conditions, while geostationary satellites help characterise cloud patterns but do not provide direct information on the air-sea interface. Recently, synthetic aperture radar (SAR) has emerged as a promising satellite technology capable of producing high-resolution two-dimensional measurements of wind speeds at the ocean surface, thanks to new acquisition modes and algorithmic developments. Given these new observational opportunities, we are exploring the contribution of near-core structural features, only discernible through high-resolution instruments, to cyclone dynamics. Using a simple theoretical framework and examining its consistency with SAR measurements, we demonstrate that surface winds near the core control the evolution of the cyclone wind structure. The framework developed illustrates how future measurements of ocean-atmosphere boundary layer characteristics could benefit from short- and long-term monitoring of tropical cyclones.
