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Abstract:
Dual-frequency GNSS receivers can be utilized to estimate the slant total electron content (TEC). Since slant TEC is integrated quantity it depends on the three-dimensional electron density distribution. Nowadays a large number of LEO satellites can provide slant TEC from altitudes between 400 and 1300 km. If occultation measurements are available, the observed altitude regimes can be extended below the F2 peak.
From GNSS slant TEC measurements a global three-dimensional model of the electron density is constructed. This model relies on cubic B-splines in magnetic latitude, magnetic local time and altitude to model the logarithmic electron density. A good coverage in all three dimensions is vital for the reconstruction. The modeled electron density is validated against insitu measurements provided by Swarm and DMSP Langmuir probe measurement. The modeled vertical TEC (vTEC) is validated using Global Ionospheric Maps provided by different processing centers and vTEC observations made by Jason-3.
The satellites included in the estimation are Swarm (A/B/C), GRACE-FO (1/2), COSMIC-2 (1-6), Sentinel (1/3), Jason-3, but also cube-sats, such as the SPIRE satellites. Special emphasis will be put on benefits gained if cube-sat missions are included to investigate the potential of constellations.
