Statistical Analysis of Scintillation Index and ROTI based on Multi-GNSS Data at Chumphon, Thailand

Ionospheric scintillation is caused by the fluctuation of electron density in the ionosphere. Severe ionospheric scintillation can degrade the Global Navigation Satellite System (GNSS) signal quality and performance. In low-latitude region, the phenomenon that may cause the ionospheric scintillation, called equatorial plasma bubble or EPB frequently arise. Rate of TEC change Index (ROTI) is utilized to detect the EPB occurrence. In this work, we aim to determine the relationship between the amplitude scintillation index (S4) and the rate of TEC change index (ROTI) at Chumphon, Thailand. The data are collected from a multi-constellation multifrequency GNSS receiver from 11 November to 31 December 2020. From the analysis, the results show that the percentage of enhanced ROTI and S4 events are 21.57% and 17.65%, respectively. Moreover, the statistical number of simultaneous enhancements of ROTI and S4 show the good correspondence. Refer to GALILEO and BeiDou, the S4 index of low frequency signal is disturbed more frequently than that of high frequency signal. However, this phenomenon cannot be seen in GPS.