SATELLITE OBSERVATIONS OF PHYTOPLANKTON VARIABILITY IN THE EASTERN EQUATORIAL PACIFIC (UPWELLING, PRIMARY PRODUCTION)

The principal objective of this study is to assess the degree to which satellite ocean color observations can be used to improve our understanding of the patterns of biological production in the eastern equatorial Pacific Ocean. Specifically, observations from the Nimbus-7 Coastal Zone Scanner (CZCS) are used to quantify the variability of phytoplankton abundance over a wide range of time and space scales.;The structure and variability of coastal upwelling regions along the Peruvian coast are described through the use of CZCS imagery. A comparison between the patterns of phytoplankton distributions observed in the satellite images and those derived from shipboard observations, reveals that the offshore extent of the region of enhanced phytoplankton concentrations is significantly greater than previously described. In addition, the sharp transition from enhanced to oceanic conditions that is seen in the CZCS images suggests that physical rather than biological factors may control the shape and offshore extent of the region of enhanced phytoplankton abundances. Satellite data are also used to describe the short-term variability of the coastal upwelling system to changes in atmospheric forcing.;This study documents that significant interannual variability in the areal extent of the region of enhanced biological production, referred to as the productive habitat, exists even under non-perturbed (i.e. non-El Nino) conditions. Using some basic assumptions and the quantitative information contained in the CZCS data, it is shown how the increased spatial coverage offered by satellites may significantly reduce the errors associated with regional primary production estimates.;Mesoscale variability of phytoplankton biomass around the Galapagos Islands as well as the spatial extent of the region of enhanced phytoplankton production associated with the islands, is shown to be associated with large-scale oceanic and atmospheric circulation patterns. Satellite ocean color observations are used to document the effect of the 1982-83 El Nino on the distributions and abundances of phytoplankton throughout the eastern equatorial Pacific.