Joint analysis of temperature and ocean colour satellite images for mesoscale activities in the Gulf of Biscay

Abstract

In the framework of the Ocean Colour European Archive Network (OCEAN) programme of the European Commission and the European Space Agency, a joint team composed of ACRI, GM-Images and Ecole des Mines de Paris proposed to analyse jointly Coastal Zone Color Scanner (CZCS) (chlorophyll) and Advanced Very High Resolution Radiometer (AVHRR) (temperature) data in order to study mesoscale dynamics features in the Gulf of Biscay. A large archive of AVHRR data, between 1978-1990, was analysed with the support of EPSHOM (Etablissement Principal du Service Hydrographique et Oceanographique de la Marine), together with about one hundred pairs of AVHRR and CZCS images. The method used to process AVHRR and CZCS data is presented in this paper. Interesting oceanographic results have been obtained. Mesoscale features such as eddies and plumes have been observed and detailed. Thestructures have been identified and classified according to an accurate typology. The appearance and evolution of mushroom-like structures have been noted, which may promote a high efficiency in the mixing of water masses. The benefit of the fusion of images is discussed. Although the locations of structures observed in both image types differ perceptibly, the increased number of observations leads to better mapping and monitoring of the features, both in space and time.