Figure 10. Comparison of sea surface nitrate concentrations, data (+), "Standard" model (solid line), and "NO3 Restoring" model (dotted line). See Table 1 for model descriptions. Since the processes controlling the model nitrate distribution (vertical mixing, isopycnal ventilation, and advection by wind-driven currents) are not well constrained, this aspect of the model performance cannot be used as verification of model integrity. However, the model nitrate distribution must at least resemble the observations, in order to replicate the carbon and oxygen dynamics.