Numerical analysis for a combined space-time discretization of air-sea exchanges and their parameterizations
Speciality : Mathématiques Appliquées
23/11/2022 - 14:00 Simon Clement (UGA) Bâtiment IMAG - Auditorium
Numerical models of the ocean and atmosphere are essential for the understanding of the associated geophysical phenomena. The coupling of these models plays a key role for a wide range of time scales (diurnal cycle, tropical cyclone, global climate...) where it is necessary to represent the interactions between the ocean and the atmosphere. The implementation of the coupling is generally done only partially and introduces a numerical error that should be minimized. For this purpose, iterative coupling methods and their convergence speed are considered here, the current practices being often equivalent to a single iteration. A difficulty in the mathematical convergence analysis of coupling methods is the presence of a surface layer between the ocean and the atmosphere. This specificity justifies studying the convergence at the discrete level (i.e. taking into account some implementation choices) rather than at the continuous level. Moreover, the parameterizations of the surface layer are based on assumptions which are not mathematically enforced within the models. This thesis proposes to consolidate the coherence between the computation of turbulent flows in the surface layer and the discretizations of the equations describing the ocean and the atmosphere. The analysis of the surface boundary layer within the ocean-atmosphere coupling is carried out here using a hierarchy of models allowing to obtain both mathematical results and the replication of numerical behaviors of interest.
- Eric Blayo (UGA )
- Florian Lemarié (UGA )