The topic of the paper is quantitative skill assessment in numerical flow modelling. Conceptual model definition, discretization aspects, quality assessment of the various types of model input data and model validation data, quantitative and objective norms and criteria for validation and assessment of results are discussed. Introductory sections discuss the definition of the concepts and terminology, and the characterization of the types of geophysical data that are used. This is followed by addressing the need for explicit model definition. In a further section we discuss the well-known method of the not formally structured process of calibration and validation by hand through visual inspection of the results, based on knowledge of the processes and insight. The strong potential of the newly available automatic parameter identification techniques to support insight and knowledge is discussed as well. The various aspects are illustrated on the step by step set up and validation of the Dutch Continental Shelf Model. This model is extensively used for simulation of tide and surge on the Northwest European Continental Shelf. The integration of a dedicated version as a module for six-hourly surge forecasting in the automatic production line of the Royal Netherlands Meteorological Institute (KNMI) is discussed next. It serves as a vehicle to illustrate the crucial aspects of elicitation, quantification and actual guaranteeing of skill and quality that is required when one applies a model as an fully operational decision support tool. In the success of such applications the model's extension with data-assimilation schemes and its interfacing with other models which provide input data play a key role. To preserve model integrity and model skill, the automatic input of time varying field data requires a rigorous automatic data-quality screening, however. The paper shows that the concepts and tools for quantitative skill assessment of coastal ocean models — particularly for water levels — exist; conscientious application will lead to a model whose skill can be assessed quite clearly in an explicit, objective and quantified manner.
H Gerritsen, JW de Vries, M Philippart. The Dutch Continental Shelf Model