Assessing ionospheric response during some strong storms in solar cycle 24 using various data sources

We present an analysis of a regional ionospheric response during six strong storms (-200\ nT\ <=Dst<=-100\ nT) that occurred in 2012 for the geographic latitudinal coverage of 10\textdegreeS\textendash40\textdegreeS within a longitude sector of 10\textdegreeE\textendash40\textdegreeE. Although these storms occurred during the same solar activity period and were all coronal mass ejection driven, their impacts and associated features on the ionosphere have been found different due to different contributing factors to their driving mechanisms. With the exception of one case, the rest of the storm periods were characterized by positive storm effects during the main and (or) recovery phases with varying physical mechanisms including low-latitude electrodynamics, neutral composition changes, and traveling ionospheric disturbances (TIDs). The common result to all the analyzed strong storms was the presence of large-scale TIDs during the storm main phases. Using total electron content data derived from the Global Navigational Satellite System (GNSS) observations and radio occultation (RO) electron density data on a regional scale, we have attempted to investigate meridional and vertical propagation of TIDs simultaneously during the strong storms. We have showed that it is possible to identify vertical motion of TIDs using RO data in cases when equatorward TIDs, as revealed by GNSS total electron content data, are present. RO results were compared to ionosonde data, and both data sources gave vertical velocities below 100\ m/s of the associated TIDs.