Models of the ionosphere, used in applications for the prediction or correction of propagation effects on practical radio systems, are often inadequate in their representation of the structure and development of large-scale features in the electron density. Over northern Europe, characterization of the main trough presents particular problems for such empirical or parameterized models and hence for radio propagation forecasting and ionospheric mapping. Results are presented from a study aimed at investigating the possible role of radio tomographic imaging in adapting models to yield a better representation of the ionosphere over Europe. It is shown that use of radio tomography gives better agreement with actual ionosonde data than can be obtained from any of the models used alone. It is suggested that the technique may have a possible role in the mapping of ionospheric conditions in near-real time for future systems applications.