Total Electron Content

GPS dual-frequency measurements are used for the total electron content (TEC) calculation applying a computational procedure based on the ‘geometry-free’ combination of the GPS code and phase measurements for resolving the ambiguities. Receiver and satellite group delays are estimated by modelling the slant TEC with a simple polynomial depending on latitude and local time. The conversion to vertical TEC is performed by assuming the standard ionospheric thin-shell model at a mean ionospheric height of 350 km. The estimated accuracy is within 2-3 TECU .

The operational service provides the vertical TEC calculated from GPS measurements at the following stations: