The Global Assimilation of Ionospheric Measurements (GAIM) model has been running operationally at the Air Force Weather Agency (AFWA) since January 2007. This is our first true data assimilative capability for space weather. Currently, the GAIM model assimilates three types of data – TEC measured by ground-based GPS receivers, electron density profiles from ground-based ionosondes, and in-situ electron densities measured by DMSP spacecraft. Over the next several years, we will work to mature the modeling capability to assimilate additional data including SSUSI, SSULI, GUVI, and COSMIC data. We will also work to characterize the sensitivity of the model to each of these data sources. This information is important to characterize the confidence in warfighter products produced, and can also be used to justify funding for data.