BIOLOGICAL-PHYSICAL COUPLING IN THE CENTRAL EQUATORIAL PACIFIC DURINGTHE ONSET OF THE 1997-98 EL-NINO

Perturbations to phytoplankton biomass associated with the onset of th e 1997-98 El Nino event are described and explained using physical and bio-optical data from moorings in the central equatorial Pacific. The physical progression of El Nino onset is depicted, from reversal of t he trade winds in the western equatorial Pacific, through eastward pro pagation of equatorially trapped Kelvin waves and advection of waters from the nutrient-poor western equatorial warm pool. Fluctuations in c hlorophyll and quantum yield of fluorescence are tightly coupled to th ermocline variations.