Preferential uptake of over in marine ecosystem models: A simple and more consistent parameterization

Here we present and analyse the behaviour of four different parameterizations of the preferential uptake of NH 4 + over NO 3 − . The first three (Wroblewski–Fasham, Spitz, Hurtt and Armstrong) are commonly used in current marine ecosystem models. However, they show either formulational inconsistencies (e.g. Wroblewski–Fasham), unrealistic features (e.g. Spitz) or structural rigidity (e.g. Hurtt and Armstrong). We therefore suggest a newer parameterization by slightly modifying the Wroblewski–Fasham formulation that easily overcome these deficiencies and could be used in the next generation of marine ecosystem models.