It is known that GNSS signals propagating through the Earth’s ionosphere have rapid variation of their amplitude and phase referred as scintillation which is caused by ionospheric irregularities. The spatial and temporal dynamics of the ionospheric fluctuations depends on space weather conditions. Scintillation dominantly occur in the equatorial ionospheric anomaly (EIA) region and in auroral regions. We report the first results on the study of the highand low-latitudes ionospheric irregularities measured from Korea Ionospheric Scintillation Sites (KISS) during the period of the 2015 St. Patrick’s Day storm. In this paper, we present methodology for GNSS ionospheric irregularities related with ionospheric scintillation. The data for the ionospheric irregularities are collected from Kiruna (geographic: 67.9° N, 21.4° E; geomagnetic: 65.2° N 127.3° W) in Sweden in auroral oval and Chuuk (geographic: 7.5° N, 151.9° E; geomagnetic: 0.5° N 136.0° W) in Micronesia in equatorial region. We used GPS ROTI (Rate of TEC Index) values to study the occurrence of TEC fluctuations. The ROTI is defined as the standard deviation over 5 minutes of the rate of TEC change. The ROTI values are calculated over five minute period with running window for each stations. The ROTI values are generally corresponded to the GNSS signal phase fluctuations. We will discuss a mechanism sources for the occurrences and magnitude of GPS TEC fluctuations during the period of geomagnetic storm events.

Keywords: 2015 St Patrick’s day storm, ionospheric irregularities, ROTI

Speaker Jong-Kyun Chung*