FORMOSAT-3/COSMIC Observations of the Ionospheric Response to Geomagnetic Activities Characterized by Global Indices

The ionospheric plasma usually responds drastically to severe space weather conditions, signified by strong magnetic field disturbances in the near-Earth environment. The level of disturbances is often well characterized by global indices such as Kp and Dst. Our statistical studies examine the ionospheric electron density under different levels of geomagnetic activities, as characterized by such indices. The studies are based on observations from the GPS occultation experiment (GOX) aboard the six satellites of the FORMOSAT-3/COSMIC mission, a Taiwan-US collaborative project that has been providing, among other data, observations of vertical electron density profiles of the ionosphere up to 800 km altitude since 2006. The focus of our studies is on the statistical change in the F2-layer peak density and its corresponding height, as well as the total electron content (TEC) at the various regions of the global ionosphere due to the effects of geomagnetic disturbances. We discuss the reasons for the spatial and temporal variations in those quantities associated with electron density.