Characterization of Ionospheric Disturbances Following Multiple Typhoons Using GPS‐Derived TEC

Abstract

AbstractTyphoon is one of the major hazards in ocean coastal areas, but traditional techniques are inadequate to monitor typhoons due to limited or high‐cost observations, like radio sounding and meteorological radar. Previous studies have found that typhoons can cause ionospheric disturbances, but the relationship and characteristics are still unclear. In this paper, about 400 stations observations of the Global Positioning System (GPS) network in Taiwan are used to extract ionospheric disturbances during multiple typhoons. The detailed characteristics of the ionospheric disturbances are investigated using a fourth‐order Butterworth filter following the 2016 Nepartak, 2019 Lekima, 2019 Mitag, and 2020 Hagupit typhoons. The results show that significant ionospheric disturbances were observed during the typhoons, and the larger disturbances are mostly located 400–1200 km far from the typhoon eye. The estimated horizontal propagation velocity of the ionospheric disturbances is about 127–194 m/s. The locations of the ionospheric disturbances between the typhoon eye and the landfall site are related to the typhoon path. The azimuth distribution of the ionospheric disturbance around the typhoon eye is affected by the GPS elevation angles. At 500–700 km from the typhoon eye, the mean ionospheric disturbances are 0.17 TECU (TEC Unit) and 0.15 TECU for super typhoon Nepartak and Lekima, and 0.13 TECU and 0.18 TECU for typhoon Mitag and Hagupit. The higher the intensity of the typhoon is, the greater the magnitude of the ionospheric disturbance is.