A Local Empirical Model of the E and F Region Ionosphere Based on 30 Years of Millstone Hill Incoherent Scatter Radar Data Holt, J. M., S. R. Zhang MIT Haystack Observatory, Route 40, Westford, MA 01886 United States Improved specifications and predictions of the ionosphere/thermosphere system are an important objective of the National Space Weather Program. As a contribution toward meeting this objective, we are developing a series of empirical models of the average behavior and variability of key parameters which characterize the ionosphere/thermosphere system. Here we present a local model of the E and F regions above Millstone Hill (42.6 N, 288.5 W) based on Millstone Hill Incoherent Scatter Radar data from 1970 to the present. The model parameters are electron density, ion temperature, electron temperature, geomagnetic-field-aligned ion drift and electric field. Time resolution is one hour, seasonal resolution is one month, altitude coverage is 100-1000 km and altitude resolution ranges from 5 km in the lower E-region to 300 km in the upper F-region. The model includes solar flux (F10.7) and geomagnetic activity (Ap) dependencies. Software to recover model values as well as a Web interface to the model is available at http://www.openmadrigal.org.