A simple 3-D biogeochemical model is coupled to a dynamical model forced by
weekly winds deduced from ERS1 scatterometer data, to simulate new product
ion in the equation Pacific from April 1992 to June 1995. The biogeochemist
ry is modelled as a nitrate sink modulated by chlorophyll, using nitrate/ch
lorophyll regressions derived from field data. The first simulation was car
ried out assuming that remineralization below the euphotic layer is totally
controlled by sinking particles. In the second simulation, it is shown tha
t the simulation of nitrate and new production by the biogeochemical model
is improved, in comparison with field data, by adding an explicit dissolved
organic nitrogen compartment. In the equatorial band, the model simulates
a nitrate-poor region (low new production) in the fresh warm pool separated
from richer waters of the upwelling region by a salinity front. The zonal
displacement of this salinity/nitrate front is associated with the El Nino-
Southern Oscillation (ENSO). The modelled new production and physics, both
in good agreement with the field data, represent useful tools for the study
of skipjack tuna (Katsuwonus pelamis) forage distribution in the Pacific.