Gian-Kasper Plattner, Nicolas Gruber, Hartmut Frenzel, and James C. McWilliams, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, USA
We investigate the relationship between annually integrated new and export production for the central Californian marine upwelling system using an eddy-resolving coupled physical-ecosystem-biogeochemical model. We find that when averaged over the annual cycle lateral transport leads to a substantial spatial decoupling of export from new production, with a length-scale of decoupling on the order of 300 km. The decoupling is largely caused by mean horizontal fluxes induced by persistent meso- and submesoscale circulation structures and to a lesser degree by the mean lateral offshore transport induced by Ekman transport. This indicates that the concept of numerically equal new and export production has to be used with great care, particularly in dynamic oceanic environments.