Ionospheric response and the impact on GPS positioning accuracy during the Tonga volcano eruption on 15 January 2022

Abstract

The characteristics of ionospheric disturbances and GPS positioning accuracy during the eruption of the Hunga Tonga-Hunga Ha'apai (Abbreviated as 'Tonga' in this paper) on January 15, 2022 are investigated using International GNSS Service (IGS) and Swarm data. Firstly, the comparison of ionospheric responses between on January 15, 2022 and November 5, 2021 is conducted. The result shows that the number of the rate of TEC index (ROTI) values more than 0.5 TECU/min during Tonga Volcano eruption was significantly larger under the same moderate geomagnetic storms. Moreover, the values of Detrend Vertical Total Electron Content (DVTEC) above IGS stations were increased to 0.3–1 TECU on January 15, 2022. An interesting finding is shown that there was a linear corrleation between the DVTEC increment and the distance from the stations to Tonga Volcano. On the contrary, the DVTEC values on November 5, 2021 were all less than 0.1. Secondly, GPS positioning accuracy on January 15, 2022 and November 5, 2021 is analyzed, respectively. The GPS positioning accuracy was declined on January 15, 2022. Even, the GPS positioning errors of some stations were larger than 3 m. By comparision, the GPS positioning errors of the studied IGS stations on November 5, 2021 were all less than 0.2 m. The above comparison result indicates that the Tonga Volcano eruption on January 15, 2022 could affect the GPS positioning accuracy. At the same time, the GPS cycle slips of the studied IGS stations are obviously enhanced during the Tonga Volcano eruption. Finally, the interaction mechanism between the Tonga volcano eruption, ionospheric disturbances and GPS positioning accuracy is discussed and explored.