Space Weather Monitoring by Ground and Space Based GNSS Measurements

Due to the dispersive nature of the ionosphere dual frequency GNSS measurements may effectively be used to derive robust and accurate information of the ionospheric state under quiet and perturbed space weather conditions. Whereas ground based measurements enable mapping of the total ionization of the ionosphere (Total Electron Content - TEC), space based measurements such as radio occultation and navigation measurements onboard CHAMP are powerful to explore the vertical distribution of the ionospheric plasma. Ground and space based GNSS monitoring techniques provide different views on ionospheric perturbation processes. The analyzed storms propagate primarily from high towards low latitudes at the European sector. Analysis of GPS measurements reveals different perturbation types such as large scale ionization fronts or wavelike Traveling Ionospheric Disturbances (TIDs) whose characteristic parameters are discussed. The measurements provide some indications for the action of perturbation driving dynamic forces, e. g. electric field induced plasma uplifting during the onset phase of severe storms. In order to permanently monitor the ionospheric state and in particular to detect and trace space weather effects, a Space Weather Application Center Ionosphere (SWACI) is being established at DLR Neustrelitz. The project shall help GNSS users to overcome problems in navigation data processing related to space weather events. To improve the service, the use of a perturbation index or indices is suggested.