Couplage des observations spatiales dynamiques et biologiques pour la restitution des circulations océaniques : une approche conjointe par assimilation de données altimétriques et de traceurs
A noter que cette thèse a été réalisé au sein de l’équipe MEOM. C’est donc un mémoire LEGI / LGGE.
Abstract
High resolution sensors of tracers such as the Sea Surface Temperature or the Ocean Color reveal small structures at the submesoscale, which are not seen by altimetry. Therefore, this thesis explores the feasibility of using tracer information at the submesoscales to complement the control of ocean dynamic fields that emerge from altimeter data analysis at larger scales. To do so, an image data assimilation strategy (i.e. inversion of images) is developed in which a cost-function is built that minimizes the misfits between image of submesoscale flow structure and tracer images. In the present work, we have chosen as an image of submesoscale flow structure the Finite-Size Lyapunov Exponents (FSLE). This method has been successfully tested on several areas using tracer and altimetric observations from space A high resolution physico-biogeochemical coupled model of process and a high resolution realistic model of the Solomon sea have been used to assess the error associated with the inversion and the efficiency of the correction on the oceanic circulation. These results show the benefits of the joint use of tracer image and altimetric data for the control of ocean circulations.
Key words :
Oceanic circulation, Submesoscale, Remote Sensing, Altimetry, Tracers observations, Ocean color, Numerical modeling, Lyapunov Exponents, Data Assimilation.