We are currently utilizing the Parameterized Real-Time Ionospheric Specification Model (PRISM) as a platform for deriving real-time regional ionospheric specification. This application involves supporting PRISM with a limited set of real-time sensor input and obtaining from PRISM a specification of ionospheric densities over a region extending to a radius of 2000--3000 km. In the initial work on this effort we have examined both data assimilation and model validation techniques, on a regional basis. We seek improved techniques for regional ionospheric specification using primarily GPS and ionosonde data as model input and mechanisms for both after-the-fact and real-time assessment of the quality of the resulting specification. We will examine, for one region, data selection and application, data quality and accuracy, and approaches for obtaining a figure of merit on the specification product. We will present some results from a short regional test of these methods and discuss issues involved in generalizing to larger studies and other regions. ¿ 2001 American Geophysical Union