Statistical modeling of environmental functional data: application to the analyse of oceanographic profiles

• Main Author: Bayle, Séverine
• Other Authors: Biostatistique et Processus Spatiaux (BioSP), Institut National de la Recherche Agronomique (INRA), Université de la Méditerranée (Aix Marseille 2), MONESTIEZ Pascal, NERINI David
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2014
• Subjects: chlorophylle-a; Analyse de données fonctionnelles; Modèle linéaire fonctionnel; spline; krigeage fonctionnel; océan Austral; mésoéchelle; [STAT.AP]Statistics [stat]/Applications [stat.AP]; [SDE.MCG]Environmental Sciences/Global Changes; Antarctic; Austral; Îles Kerguelen; Kerguelen; Southern Ocean; The Antarctic; Antarc*; Antarctique*; Elephant Seals
• Online Access: https://hal.inrae.fr/tel-02797360

To study biogeochemical processes in the Southern Ocean, tags placed on elephant seals allowed to collect during 2009-2010 oceanographic variables profiles (Chlorophyll a (Chl a), temperature, salinity, light) in an area ranging from southern Kerguelen until the Antarctic continent. This thesis focuses on Chl a data as it is contained in photosynthetic organisms and these ones play an essential role in the oceanic carbon cycle. The infrequently collected vertical Chl a proles don't provide a mapping of this variable in this area of the ocean. However, we have light profiles sampled more often. The aim of this thesis was then to develop a methodology for reconstructing indirectly Chl a profiles from light profiles, and that takes into account characteristics of this kind of data that naturally occur as functional data. For this, we adressed the pro les decomposition to rebuild or explanations on splines basis, as well as issues related adjustment. A functional linear model was used to predict Chl a profiles from light profiles derivatives. It was shown that the use of such a model provides a good quality of reconstruction to access high frequency variations of Chl a profiles at fine scale. Finally, a functional kriging interpolation predicted the Chl a concentration during night, as light measurements acquired at that time can't be exploited. In the future, the methodology aims to be applied to any type of functional data. Keywords : Functional Data Analysis, functional linear model, spline, chlorophyll-a, functional kriging, Southern Ocean, mesoscale. Afin d'étudier les processus biogéochimiques de l'Océan Austral, des balises posées sur des éléphants de mer ont permis de récolter en 2009-2010 des profils de variables océanographiques (Chlorophylle a (Chl a), température, salinité, lumière) dans une zone s'étalant du sud des îles Kerguelen jusqu'au continent Antarctique. Cette thèse se penche en particulier sur les données de Chl a, car celle-ci est contenue dans les organismes photosynthétiques qui jouent un ...