Interface-based Support for Model Coupling: Spatial Representation and Compatibility Issues

Model coupling is a nontrivial task that is not adequately supported in existing frameworks. Our long-term goal is to support the fast-prototyping of model couplings, enabling scientists to quickly experiment with a variety of linkings without having to make an upfront investment in reprogramming. The centerpiece of our framework, the Potential Coupling Interface (PCI), must expose all the characteristics of a model that are relevant to model coupling, but what are those characteristics? To explore different couplings, and to identify the relevant model characteristics, we conducted a study of 14 hydrological models and the pairwise couplings between them. We found that the model characteristics relevant to coupling lie in four dimensions: space, time, structure, and data. Models of the same phenomena often had similar characteristics, making it feasible to replace them within a coupling when appropriate for specific sites. We also found that resolving differences along the four dimensions, particularly with respect to space, can be complex.