Global eddy permitting simulations of surface ocean nitrogen, iron, sulfur cycling

The geocycles of N, Fe and S in the ocean are tightly coupled and together exert strong influence on biogeochemistry of the earth system. We investigate this interaction by inserting macro–micronutrient cycling into a high resolution ocean model that realistically represents the general circulation. Simulated chlorophyll distributions reproduce many features of satellite-based measurements of ocean color. Meridional sections through model results and seasonally averaged SeaWiFS data agree reasonably well, both in the oligotrophic gyres and along fronts. Discrepancies are associated in many cases with shelf, ridge or island effects. Dimethyl sulfide peaks and their chlorophyll correlations are similar to those obtained on major oceanographic expeditions. Lack of strong regional relationships between the sulfide and phytoplankton may be partly explained by correspondence between time constants for production and for the traversal of mesoscale transport features. In general the eddies and filaments of tropical instability waves are well represented, including the onset of the 1997–1998 El Niño. North–south shifts of the transition zone chlorophyll front appear prominently in the results.