Satellites in Low Earth Orbit (LEO) are essential for sounding the topside ionosphere. In this work, we present and validate a data set of Total Electron Content (TEC) and in situ electron density observations from the Gravity Recovery And Climate Experiment (GRACE) and GRACE-Follow-On missions as well as a TEC data set from the CHAllenging Minisatellite Payload mission. Concerning TEC, special emphasis is put to ensure optimal consistency to the already existing Swarm and Gravity field and steady-state ocean circulation explorer (GOCE) TEC data sets. The newly processed satellite missions allow covering two full solar cycles with LEO slant TEC. Furthermore, the twin satellite missions GRACE and GRACE-FO equipped with inter-satellite K-band ranging allows to derive the horizontal TEC and, due to the small inter-satellite distance of the satellite pairs, an approximation for local electron density. However, the derived value of electron density is relative and requires calibration using external information. In this work, the calibration is performed using the IRI-2016 model. Radar observations, as well as in situ electron density observations available from Swarm B Langmuir probes, are used for validation. Conjunctions between satellites are used to validate the TEC time series. The newly derived data set is shown to be highly consistent with the already existing data sets with standard deviations below 3 TECU for TEC (even 1 TECU was reached for low solar flux) and an offset below 7 × 10¹⁰ m⁻³ with a standard deviation near 1 × 10¹¹ m⁻³ for the electron density.

Transient signal loss of the global positioning system (GPS) has been frequently observed by receivers on board the European Space Agency's Swarm mission when the satellites encounter ionospheric plasma irregularities. In this study we provided the first comparison of the GPS signal amplitude degradations from receivers on board low Earth orbiting satellites at different altitudes. Intense carrier phase variations but almost no amplitude fades (less than 2 dB Hz) are observed when the spaceborne receiver lies right inside the ionospheric plasma irregularities, like the case for the Swarm and CHAMP satellites flying at about 400–500 km. This indicates that the strong phase variation, but not the amplitude fades, causes the receivers to stop tracking the GPS signals. When the receiver is located 100–200 km below the slab of plasma irregularities, like the case for the GOCE satellite flying at about 250 km, signal amplitude fades exceeding 10 dB Hz are observed, in addition to strong phase variation. Our results suggest that a considerable distance of the receiver to the plasma irregularity slab is needed to affect the Fresnel diffractive process and further causes GPS signal amplitude fades.