Tropical cyclone effect on ionosphere parameter variations in Siberia and Far East

We revealed 1-5 h time intervals with higher oscillation energetics along the Norilsk-Irkutsk, Magadan-Irkutsk, and Kha-barovsk-Irkutsk paths (Siberia and Far East) during equinoctial periods (March, September 2005-2011), in November, 2005 and during summers in 2010 and 2011. The data from frequency analysis by maximal observed frequencies (MOF) for the oblique sounding (OS) signals were used. These time intervals may be interpreted as a manifestation of large-scale traveling ionospheric disturbances (TIDs) whose sources are atmospheric internal gravity waves (IGW). By jointly analyzing ionospheric, heliogeomagnetic, atmospheric, and satellite data on tropical cyclones (TCs), we attempted to associate the series of the revealed TIDs with ionospheric responses to TCs that were in effect over the northwestern Pacific during the above periods. A significant increase in wave disturbances on OS paths was established to be noted during active tropical cyclogenesis periods in autumn months. The TID intensity decreases as the OS path medium points move away westward from IGW potential sources. We note different responses of the ionosphere to wave disturbances' passing from the same IGW sources for OS paths under analysis. We estimated the wave disturbance propagation velocity by the delay time of TID passing the medium points of the spaced OS paths. For spring equinox (March, 2005-2011), we also note TID manifestations in MOF temporal variations under quiet heliogeomagnetic conditions and in TC absence, but the intensity of these wave disturbances is significantly lower, than that of autumn seasons for various years.