Comparative study of GPS-TEC smoothing techniques

The availability of permanent global positioning system (GPS) stations makes the ionosphere monitoring and space weather studies more attainable. In order to obtain precise ionosphere total electron content (TEC) measurements, a smoothing technique has to be used. The objective of this research is to examine the accuracy and performance of two different TEC smoothing techniques; the carrier phase smoothed code and code levelled carrier phase techniques. GPS data from three stations in North America, located in different latitudes, are used. The accuracy of the smoothed TEC is compared with international GNSS service global ionospheric maps (IGS-GIM) and national oceanic and atmospheric administration (NOAA) ionospheric maps. The results reveal that the accuracy of the estimated TEC from the phase-smoothed code method depends upon the quality of data, number of observations used in the smoothing interval, receiver and satellite differential code biases (DCB). The levelled carrier phase method produces more calibrated TEC, however, with the influence of the systematic errors and the differential code biases.