Geostationary satellites as a strategic tool for real-time ionospheric monitoring
Various natural and man-made hazards, including tsunamis, earthquakes or explosions, produce atmospheric internal gravity waves (IGWs), acoustic waves, and acoustic-gravity waves that could vertically propagate to the E and F regions of the ionosphere thereby generating spatial and temporal electron density disturbances known as Travelling Ionospheric Disturbances (TIDs). These ionospheric disturbances are investigated in detail using ionospheric total electron content (TEC) measurements collected by continuously operating ground-based Global Navigation Satellite Systems (GNSS) receivers. The GNSS satellites are usually located in Medium Earth Orbits (MEO) at an approximate altitude of 20,200 kilometers, which yields an orbital period of about 12 hours (in case of the GPS satellites).
The aim of the research is to leverage the VARION (Variometric Approach for Real-Time Ionosphere Observation) algorithm which is able to estimate TEC variations in real-time and already successfully used with MEOs, for geostationary satellites (GEOs). The main advantages of applying the VARION algorithm with GEO observations are the removal of all geometry effects, which may help the TIDs detection, and the ability to provide continuous time series, useful to monitor the ionosphere activity.
Nonetheless, GEOs have lower spatial coverage, indeed they are few GEOs satellites in orbit, even if the increasing of private companies operating in space business and the new Beidou geostationary satellites denote a positive trend in this direction.
In conclusion, VARION application to GEO satellites can improve real-time tsunami TIDs detection and help to separate time/space ionospheric variability, representing at the same time a new challenge for the VARION algorithm.