On the mathematical formulation and parameter estimation of the Norwegian Sea plankton system

The mathematical description of the oceanic plankton system is often charac terised by a simple structure where the major components of the system are governed by the dissolved nutrient concentration N, the phytoplankton bioma ss I: and the zooplankton biomass Z (also known as the NPZ model). The flow s between the variables can be formulated in a variety of ways that, in gen eral, alter the time development of the model. In this study we investigate how the numerical value of model parameters that are hard to determine exp erimentally can be estimated from in situ field observations. By that, we c an assign parameter values to each model Formulation such that they should follow a prescribed time development that is consistent with data. Accordin gly, this gives us a tool to compare model formulations in a consistent way . The study emphasises the importance of analysing the model with respect t o stability and multiple solutions. The study is exemplified using observat ions from Ocean Weather Station Mike (66 degreesN, 2 degreesE) in the Norwe gian Sea, illustrating the need for a proper model formulation in order to reproduce measurements.