Recent Improvements to Global Plasmasphere Ionosphere Density (GPID) Model and Comparisons with Satellite Plasmaspheric Observations P. A. Webb, R. F. Benson NASA/GSFC, Greenbelt, Maryland 20771 B. W. Reinisch University of Massachusetts at Lowell, Lowell, Massachusetts 01854 The presentation will cover the recent development that has occurred with the Global Plasmasphere Ionosphere Density (GPID) model, a dynamic global model of the plasmasphere. GPID was originally developed to estimate the plasmaspheric contribution to total electron content (TEC) measurements obtained from ground-based receivers derived from radio signals transmitted from Global Position System (GPS) satellites. Results of comparisons with plasmaspheric TEC obtained from Low Earth Orbit (LEO) satellites equipped with GPS receivers will be shown. The Radio Plasma Imager (RPI) carried by NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite can determine the local electron densities from passive measurements, as well as magnetic field-aligned electron-density profiles calculated from active soundings. Examples of comparisons of both these types of RPI observations with the predictions made by GPID will be presented. These comparisons will include examples where RPI observations have lead to improvements in GPID. _______________ To be presented at the 2002 Spring A.G.U. Meeting, Washington, D.C., U.S.A., 28-31 May 2002