Integrated modelling of suspended matter in the North Sea

The topic of this paper is the modelling of suspended particulate matter (SPM) patterns and their variation on North Sea scale over the time scale of several months. The modelling results are assessed by a formalized comparison with concentrations derived from NOAA/AVHRR reflectance imagery. The nature of the study is a sensitivity analysis of the various modules forming the integrated SPM model: the hydrodynamic model, the wave model and the SPM transport and erosion-sedimentation model. A Goodness-of-Fit criterion is introduced as a single parameter to quantify the difference between SPM model results and data. Its specification reflects the aim of the model, which in this study is the representation of the seasonal behaviour of SPM patterns, and the determination of the sensitivity to uncertainties in model parameters of the transport model, its inputs and forcing or boundary conditions. This Goodness-of-Fit method is applied to a North Sea wide scale SPM model application in both 2-D and 3-D using a curvilinear grid schematization. Results are presented for the period March-September 1994. The results confirm the suitability of NOAA/AVHRR based data to assess the modelling and the importance of the net volume flux which is input to the SPM model. The uncertainties in the present estimates of inputs from e.g. erosion and dumping, and the erosion-sedimentation model parameters are shown to also have a major impact on the modelling results. The approach using the Goodness-of-Fit criterion as such is shown to lead to an objective and reproducible quantification of the model quality. (C) 2001 Academic Press.