GNSS TEC Calibration
TEC data are derived from carrier phase measurements for both GPS or GPS+GLONASS satellite systems.
The basic relation used to calibrate the TEC is as follows:
S Φ = sTEC + βias arc
where:
S Φ is the ionospheric delay from the raw carrier phase observations,
βias is the arc-offset, a constant to be determined for each arc of observations related to a given receiver and satellite pair. βias represents the contribution of receiver and satellites biases (δbR, δbs), and the contribution of any non-zero averaged errors over an arc of observations, e.g. the multipath (<δm>arc).
A two-dimensional thin shell model at 350 km is used to define the mapping function between the slant and vertical TEC. The vertical ionospheric variation is expressed as a function of the modip and the Local Time of the ionospheric pierce points (IPPs).
GNSS TEC Calibration online (On demand service)
Reference: Ciraolo, L., et al. "Calibration errors on experimental slant total electron content (TEC) determined with GPS." Journal of Geodesy 81.2 (2007): 111-120