Merging of ocean color data from multiple sensors : application to operational oceanography

• Main Author: Pottier, Claire
• Other Authors: Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Véronique GARÇON
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2006
• Subjects: ocean color; weighted averaging; objective analysis; wavelets; Southern Ocean; space data; in situ data; données satellitaires; données in situ; couleur de l'eau; moyenne pondérée; analyse objective; ondelettes; Océan Austral; [SDU.OTHER]Sciences of the Universe [physics]/Other; Antarc*; Antarctic
• Online Access: https://theses.hal.science/tel-00179729; https://theses.hal.science/tel-00179729/document; https://theses.hal.science/tel-00179729/file/Pottier_these_06.pdf

Phytoplankton play an important role in the carbon cycle on Earth, via the carbon dioxide absorption during photosynthesis. If scientific cruises provide high frequency data at high space-time resolution, the observation from space allows a synoptic description and on long periods of chlorophyll-a, the ocean phytoplankton's main pigment. Each space mission measuring ocean color is limited in ocean spatial coverage (satellite tracks, clouds, etc.). The daily spatial coverage may increase significantly by merging datasets from several sensors. The objective of this Ph.D. was to design, develop and test different methods which combine ocean color data, from the American sensors SeaWiFS and MODIS/Aqua, for near real time applications for operational oceanography. Three concepts have been studied : error-weighted averaging (keeps the structures accuracy but uses only existing data), objective analysis (increases spatial coverage but, in return, smoothes the field), and a last new approach based on the wavelets transform (keeps the structures accuracy and increases the spatial coverage). The operationality of these three methods has been demonstrated. The relevance of using combined data was studied by highlighting the dominant modes of oceanic variability in physical and biological dynamics in the Southern Ocean, by using SeaWiFS + MODIS/Aqua combined data from the Antarctic circumpolar belt during the 2002-2006 period. Le phytoplancton joue un rôle important dans le cycle du carbone sur Terre, de par l'absorption du dioxyde de carbone au cours de la photosynthèse. Si les campagnes en mer offrent la possibilité d'acquérir des données à haute fréquence et à fine échelle spatio-temporelle, l'observation spatiale procure une description synoptique et sur de longues périodes de la chlorophylle-a, pigment principal du phytoplancton océanique. Chaque mission satellitaire qui mesure la couleur de l'eau est limitée en couverture océanique (traces du satellite, nuages, etc.). La couverture spatiale journalière peut ...