Ionospheric variations during typhoons of autumn 2016

We study variations of total electronic content (TEC) during typhoons, observed in the August-September 2016 in the North-West Pacific Ocean. The TEC data were obtained from phase dual-frequency measurements of GPS/GLONASS ground-based receivers. Using the indexes of ionospheric variability within different period ranges we revealed an increase in the intensity of ionospheric disturbances with periods of internal gravity waves (IGW-variability, from 2 minutes till 4 hours) at the stations located close to the typhoon regions. The most intensive variations are shown to be occurred after passage of the solar terminator and localized near the typhoon boundary. The greatest increase in TEC IGW-variability is recorded during the days of abrupt changes in the cyclones intensity (growth/fall in wind speed).