Ionospheric Response to the 2015 St. Patrick's Day Storm along the Longitude of 100o E

We studied equatorial and low-latitude ionospheric response to a great geomagnetic storm occurred on the 17 March 2015 using ionosondes and in situ satellite (Swarm). Some interesting ionospheric phenomena including short-term ionospheric positive effect, daytime spread F, and morning Equatorial Ionization Anomaly (EIA) in the topside ionosphere have been presented in our study. We suggested that the short-term ionospheric positive effect at the main stage of this great storm is related to vertical downward transport of plasma or neutral gas; Observations of daytime spread F at low latitudes might be attributed to the diffusion of equatorial ionospheric irregularities in the topside ionosphere along geomagnetic field lines; TIDs might play a significant role for morning EIA-like feature recorded by Swarm B satellite in the topside ionosphere.