Comparison of performance of selected ionospheric models used for GNSS positioning

An evaluation of ionospheric corrections derived from the two global total electron content (TEC) maps, Neustrelitz DLR/GIM and Centre for Orbit Determination in Europe CODE/GIM, for the mitigation of ionospheric threats to precise GNSS positioning, has been carried out. Investigations to both models have been performed using the following empirical approaches:
1) Coordinate Domain: Processing of selected static dual frequency GPS data in relative pseudo-kinematic mode, taking ionospheric corrections from the two selected models, to solve position at every observational epoch. Comparison of the obtained results (time series of co-ordinates) with precise reference coordinates of the station calculated over a long time period.
2) TEC Correction Domain: Calculation of the time series of interpolated TEC values for all observation epochs using both the CODE and DLR maps, and calculation of TEC time series from the recorded GPS observations in single station. Comparison and analysis of all three sets of TEC values.
3) Calculation of the Rate of TEC (ROT) as an indicator of ionospheric irregularities.
4) Analysis of the time series of TEC, ROT and the pseudo-kinematic station coordinates to detect and identify source of anomalous signals.

Experimental GPS data from the continuously operated station at Kiruna (Sweden) located in the polar region, and Wettzell (Germany) located in the mid-latitudes, have been processed. Presents are the first results of investigations on GPS data recorded during a quiet period and under the presence of high ionospheric irregularities. Further investigations are in progress.