Large‐scale ionospheric disturbances during the 17 March 2015 storm: A model‐data comparative study

This paper presents a detailed model‐data comparative study of the 17 March 2015 geomagnetic storm using the high‐resolution version of the thermosphere‐ionosphere‐electrodynamic general circulation model and the total electron content observations from a dense global navigation satellite system network. Driven by time‐dependent high‐latitude ionospheric convection and auroral precipitation inputs, together with an empirically defined subauroral plasma stream (SAPS) field, our simulation reproduce many observed storm‐related ionospheric phenomena, including large‐scale traveling ionospheric disturbances over Europe, the effects of prompt penetration electric field over South and Central America, and the formation of a storm‐enhanced density (SED) plume across the continental United States. Our simulation results reaffirm a number of important characteristics concerning the SED plume: (1) enhanced background ionospheric density is a necessary but not sufficient condition, and enhanced ion drift is required to form the SED plume; (2) the SAPS flow channel does not directly transport the plasma from midnight to postnoon via dusk to form the SED plume, instead, the SED plume is formed at the equatorward and westward edge of the SAPS channel; and (3) the SED plume appears to subcorotate with respect to the Earth.