The real-time distribution of high-latitude ionization can be inferred by monitoring kilovolt electron precipitation. Several space-based spectrophotometric imagers have been designed for this purpose. Assessment of the capabilities of specific satellite sensors requires a model of the spatial distribution of high-latitude electron precipitation and its temporal variation. Because previous statistical models do not indicate the instantaneous spatial distribution of particle precipitation and resultant ionization, we have used an alternative phenomenological approach to model the high-latitude ionosphere. This phenomenological model specifies the instantaneous pattern of high-latitude kilovolt electron precipitation and related quantities such as ionization, conductivity, and auroral luminosities. The model specifies the temporal and spatial variations that occur during auroral substorms, based on the auroral morphology that has been deduced from optical and riometer studies. To illustrate the usefulness of the model for evaluating instrument performance, examples are shown of the simulated response of a satellite-borne X ray imager.