Detection and monitoring of algal blooms using SeaWiFS imagery

SeaWiFS (Sea viewing Wide Field of view Sensor) imagery is used to monitor the birth, development and termination of phytoplankton blooms in the north-east Atlantic. Extensive patches of water giving high reflectance of visible light were observed from the beginning of February to the end of July 1998 in the Celtic and Armorican Shelf regions between 45° and 60° N and interpreted as phytoplankton. Eighteen relatively cloud-free SeaWiFS images have been analysed in order to detect the spatial, temporal and spectral development of the blooms within the two study areas. Consistency of the spectral signature and the very high broadband reflectance leads to the conclusion that these are blooms of the widespread coccolithophore Emiliana huxley, although no in situ data during the study period are available to validate this hypothesis. The utility of SeaWiFS data for studying the life history of phytoplankton blooms is confirmed.