Spatiotemporal distribution of ionospheric irregularities over India during St. Patrick’s Day Storm

Abstract

The irregularities formed over the equatorial ionospheric region over the Indian sector have been studied for the first time for the day of the most intense geomagnetic storm of solar cycle-24, which occurred on 17.03.2015, using Rate of TEC Index (ROTI) as the index for the study. These values have been derived using the measurements done with the TEC network receivers of the Indian SBAS system, GAGAN. Spatial and temporal variations of ROTI have been observed and compared to the same parameters on a quiet day with occurrence of nominal scintillation. The latitudinal symmetry of the irregularities for a given local time was evident. It has been found that the ionospheric irregularities formed over this region get immensely enhanced due to the storm in terms of its intensity and spatial extent, as well. The temporal spread of the irregularities has been observed and the statistical variations of the occurrences were compared with respect to those on quiet days. The results have provided few interesting observations including an understanding of the profundity and extensiveness of the irregularities and of the possibilities of consequent scintillation for the navigation signal over Indian region during space weather induced intense geomagnetic disturbances.