Data/hora: 01/06/2024 07:49:29

Provedor de dados: | 5
País: | France
Título: | Apports des données de la 'couleur de l'eau' à la modélisation couplée physique-biogéochimie en milieu dynamique côtier : Application au Rio de la Plata et au Golfe de Gascogne
Autores: | Huret, Martin.
Data: | 2005-01-28
Ano: | 2005
Palavras-chave: | Parameter estimation; Data assimilation; Suspended Particulate Matter (SPM); Chlorophyll a; Phytoplankton blooms; Physical biogeochemical coupled model; Ocean color; Satellite data; Coastal area; Bay of Biscay; Rio de la Plata; Estimation de paramètres; Assimilation de données; Matières En Suspension (MES); Chlorophylle a; Blooms phytoplanctoniques; Modèle couplé physique biogéochimie; Couleur de l'eau; Donnée satellitale; Milieu côtier; Golfe de Gascogne; Rio de la Plata.
Resumo: | Continental margins play a crucial role in biogeochemical fluxes between the continents and the open ocean. They are also highly sensitive to human perturbations. Primary production is highly dependent on the complex dynamics of these coastal zones, and on the river supply in nutrients, as well as in Suspended Particulate Matter (SPM) which limit light availability. The quantification of the production is a prerequisite in many applications, from the understanding of the role of the coastal ocean in climate change, to eutrophication and fisheries resources issues within the frame of the integrated management of the coastal zone.  Coupled physical-biogeochemical models are useful in studying and monitoring primary production. Because of the numerous complex processes and their non-linear interactions, and of some poorly known parameter values, some errors remain in the simulation of the phytoplankton production  in coastal areas. Together with these models, satellite `ocean color' data is a major monitoring tool for marine ecosystems. Applying empirical algorithms to SeaWiFS data in coastal areas allows the retrieval of the concentration of chlorophyll a as well as of SPM.  This PhD. work shows the benefits of using `ocean color' data to constrain primary production models. Two study areas are investigated : the Rio de la Plata estuary and its continental margin in the Southwest Atlantic Ocean, and the Bay of Biscay in the Northeast Atlantic.   First, the analysis of chlorophyll a concentration data bases for both areas, and of SPM concentration for the Bay of Biscay, reveals major phytoplankton features and processes that should be taken into account in the model formulation. Then a simple five compartments model for the Rio de la Plata, and a more complex one for the Bay of Biscay, have been coupled to the hydrodynamic model MARS-3D of IFREMER. After a first validation step, in which major observed features are reproduced, the models constraint by ocean color data is investigated.   For the Bay of Biscay, surface forcing with satellite SPM concentrations improves the accuracy of light availability and then the simulation of late winter phytoplankton blooms. For both areas, we conducted optimisation experiments for some of the biological parameters. This parameter estimation was done on short spring periods with a global optimisation method, the Evolutive Strategies, applied to the three dimensional coupled model. The minimisation of a cost function describing the data/model misfit on surface chlorophyll a was then possible, leading to a better simulation of spring phytoplankton blooms in the plumes of the Bay of Biscay.   The use of `ocean color' data for assimilation in coupled physical-biogeochemical models is a major issue in optimizing the primary production estimation, in the frame of an operational monitoring of the coastal environnement.
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/2005/these-337.pdf
Editor: | Paul Sabatier Toulouse
Relação: | http://archimer.ifremer.fr/doc/00000/337/
Formato: | application/pdf