Research on the Spatio Temporal Characteristics of  IGS Ionospheric Products

   The research on the temporal and spatial variation of ionosphere has important value for satellite navigation, aerospace and so on. This article uses international GNSS services (IGS) products, analyze the ionospheric temporal and spatial variation. On the time scale, doing the Power spectrum analysis on the loworder spherical harmonic coefficient of (0,0)、(1,0)、(1,1)、(1,-1), and the shorttime Fourier transform of the total vertical electron content (VTEC) in the Beijing area was analyzed. Seasonal analyzes were conducted in Beijing, Accra and Melbourne, the results show that ionospheric changes have obvious annual and semiannual cycles. In the space aspect, the variation rules of the latitude and longitude of the ionosphere delay on the zero meridian and equator are analyzed. The results show that there is a single peak effect in the latitudinal direction, and the peak value in the longitude direction has a delay variation