Medium‐scale traveling ionospheric disturbances triggered by Super Typhoon Nepartak (2016)

Abstract

Abstract Two remarkable typhoon‐induced traveling ionospheric disturbances (TIDs) with concentric and northwest‐southeast (NW‐SE) alignments, respectively, associated with concentric gravity waves (CGWs) and ionosphere instabilities possibly seeded by CGWs, were observed in total electron content (TEC) derived from ground‐based Global Navigation Satellite System networks in Taiwan and Japan when the Category 5 Super Typhoon Nepartak approached Taiwan on 7 July 2016. The concentric TIDs (CTIDs) first appear with horizontal phase velocities of ~161–200 m/s, horizontal wavelengths of ~160–270 km, and periods of ~15–22 min during 08:00–11:20 UT. Following the CTIDs, the NW‐SE aligned nighttime medium‐scale TIDs (MSTIDs) are formed on the west edge of the CTIDs over the Taiwan Strait during 11:30–14:00 UT. It is suggested that the MSTIDs are produced by the electrodynamical coupling of Perkins instability and CGW‐induced polarization electric fields. This study proposes connections of typhoon‐induced CTIDs and subsequently occurring MSTIDs in the low‐latitude ionosphere.