Calibration of COSMIC Ionospheric Profiles Using Incoherent Scatter Radars

Occultations of GPS satellites as viewed from the COSMIC constellation of satellites can be used to determine the electron density as a function of altitude under certain conditions. Our goal was to examine occultations near incoherent scatter radar sites while calibrated profiles were obtained. In June 2006, three days of incoherent scatter radar data were obtained and compared to occultation data. Of the daytime profiles examined to date, two-thirds were in very good agreement. We are investigating the conditions that led to poor agreement. One possible tool we will use in exploring the role of horizontal gradients is airglow observations. Another is the spatial coverage of the radars themselves. We anticipate six more days of such comparisons in September 2006.