Assimilative Modeling of Mid-Latitude Ionospheric Plasma Plumes during the October 2003 Storm

A significant daytime ionospheric total electron content (TEC) enhancement was observed at middle latitudes by the ground-based and space-borne GPS receivers during the geomagnetic storm on October 30, 2003. This TEC enhancement has been identified as the storm enhanced density (SED). To investigate ionospheric disturbances associated with the SED, GPS data collected from 200 ground stations and two low-Earth-orbiters (CHAMP and IOX) are assimilated into Global Assimilative Ionospheric model (GAIM). For the first time, the assimilative modeling with GPS data reveals 3D ionospheric plasma plumes, i.e., enhanced electron densities showing a plume feature towards higher altitude and latitude. Compared with the quiet-time ionospheric state also obtained by assimilative modeling, the model results show that F-layer densities increase by many hundreds of percent and the layer peak rises more than 200 km at middle latitudes. The plume feature indicates a strong zonal electric field penetration during the storm is likely the cause, which also drives a very significant equatorial- anomaly-like disturbance at middle latitudes seen in the GPS data collected from the CHAMP satellite.