Delineation of seasonal changes of chlorophyll frontal boundaries in Mediterranean Coastal waters with Nimbus-7 Coastal Zone Color Scanner data

Abstract

The seasonal changes in chlorophyll-like pigment distribution in the Northwestern Mediterranean Sea (Gulf of Lions) were monitored during the year 1979. Data were collected from the Coastal Zone Color Scanner (CZCS), carried on the Nimbus-7 satellite. A series of cloud-free images covering the whole year was selected and processed to evaluate chlorophyll-like pigment concentrations. The upwelling subsurface radiance of the ocean ( L ss) was extracted from the apparent upwelling signal reaching the satellite sensor ( L O) using an algorithm removing atmospheric effects. Chlorophyll-like pigment concentration ( C) was then derived from L ss in different wavelengths. Characteristic boundaries between water masses with different phytoplankton content were obtained. The results demonstrate that phytoplankton distribution is a good indicator of seasonal variations of oceanic fronts. Features such as coastal upwellings, cyclonic eddies, or plume of the Rhône river could be monitored.