Evaluating the Predictive and Explanatory Value of Atmospheric Numeri- cal Models: Between Relativism and Objectivism

We discuss the ways in which atmospheric numerical models can be shown to have both predictive and explanatory value. This argument rests largely on the established predictive value of numerical weather forecasts, and can be extended to atmospheric models at largerand smaller scales. We demonstrate that atmospheric modellers have not been particularly critical about the logical basis of model evaluation, and recommend strategic approaches to remedy this. Our suggestions involve the creation of a spatio-temporal scale-dependent and context-relative ordinal scale for model evaluation that must be applied in an a-priori, context-dependent fashion.