[P-EM13] Study of coupling processes in solar-terrestrial system

[PEM13-04] Assessing the performance of a Northeast Asia regional ionosphere specification technique during the 2015 St. Patrick’s day solar storm

*Nicholas Ssessanga¹, Mamoru Yamamoto¹, Susumu Saito² (1.RISH, 2.ENRI)

Keywords:Ground-GNSS-STEC tomography, Ionosonde data assimilation, geomagnetic storm

This paper demonstrates and assesses the capability of the advanced three-dimensional (3-D) regional ionosphere tomography technique, during severe ionospheric conditions. The study area is northeast Asia and Japan centred. Reconstructions are based on total electron content data from a dense ground-based GPS receiver network and parameters from operational ionosondes. We used observations from ionosondes, Swarm satellites and radio occultation (RO) to assess the 3-D picture. Specifically, we focus on St. Patrick’s day solar storm (17–19 March 2015), the most intense in solar cycle 24. During this event, the energy ingested into the ionosphere resulted in Dst and Kp reaching values ~-223 nT and 8, respectively, and the region of interest, the East Asian sector, was characterized by a ~ 60% reduction in electron densities. Results show that the reconstructed densities follow the physical dynamics previously discussed in earlier publications about storm events. Moreover, even when ionosonde data were not available the technique could still provide a consistent picture of the ionosphere vertical structure. Furthermore, analyses show that there is a profound agreement between the RO profiles/in-situ densities and the reconstructions. Therefore, the technique is a potential candidate for applications that are sensitive to ionospheric corrections.