Chapter 12 An overview of temporal and spatial patterns in satellite-derived chlorophyll-a imagery and their relation to ocean processes

Abstract

Abstract Satellite measurements of water-leaving radiance, from which estimates of phytoplankton chlorophyll- a are derived, began with the launch of the Coastal Zone Color Scanner (CZCS) in 1978. Global CZCS data were widely distributed beginning in 1988, providing oceanographers a new tool for studying temporal and spatial variability in surface waters of the global ocean. CZCS imagery, and that from more recently launched sensors, has been extensively used for studies of variability at spatial scales from 10 km to the global ocean and for temporal scales ranging from days to years. Ocean margin waters have particularly strong signatures in chlorophyll- a images, and the imagery has been effectively used to study a wide range of environments, including coastal upwelling systems and river plumes. chlorophyll- a imagery is the only tool for observing the mean-and time-varying components of a biological variable at ocean basin to global ocean scales. Basin-to-global scale composite images are used as input to calculate primary production and to describe and quantify seasonal cycles on a global scale. Such images are also one of the important data sources for understanding how physical processes affect biological distributions on ocean basin and global scales, e.g., the impact of major ocean perturbations such as El Nino. Future sensors, as well as new capabilities to merge data from different sensors, will provide better accuracy and better coverage, thereby extending scientific and other applications in coastal and open ocean waters.