Quantifying Global Plasmaspheric Images With in situ Observations M.B. Moldwin Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences, UCLA, Los Angeles CA 90095-1567 USA B.R. Sandel Lunar and Planetary Laboratory,University of Arizona, Tucson AZ M.F. Thomsen and R.C. Elphic Los Alamos National Laboratory, Los Alamos NM Simultaneous IMAGE EUV plasmaspheric images and Magnetospheric Plasma Analyzer (MPA) data from the Los Alamos National Laboratory's geosynchronous satellites are combined to understand plasmaspheric behavior and to quantify the global images. A brief review of the understanding of the plasmasphere as learned from in situ observations prior to the launch of IMAGE is given to place the results presented here into context. _______________ Space Science Reviews, in press, 2003