Performance comparison of ionospheric models used for GNSS positioning

Kurzfassung

An evaluation of applicability of ionospheric corrections derived from the two global total electron content (TEC) maps, Neustrelitz DLR/GIM and Center for Orbit Determination in Europe CODE/GIM, for mitigation of ionospheric threads in precise GNSS positioning, has been done. Investigations on the both models have been performed in the following empirical approach. Investigation in the domain of coordinates: Processing of selected static GPS data in relative pseudo-kinematic mode, taking ionospheric corrections from the two selected models, to solve for position at every observational epoch. Comparison of the obtained results (time series of coordinates) with precise reference coordinates of the station calculated over a long time period. Investigation in the domain of TEC corrections: Preparation of two time series of interpolated TEC values for the all observation epochs using the CODE- and DLR maps, and calculation of TEC time series from the recorded GPS observations. Comparison and analysis of the all three sets of TEC values. Calculation of the Rate of TEC (ROT) and of scintillation index S4 as indicators of ionospheric irregularities. Analysis of the time series of TEC, ROT, S4 and the pseudo-kinematic station coordinates to detect and identify origin of anomalous signals. Experimental GPS data from the continuously operated station at Kiruna (Sweden) located at the polar region, and Wettzell (Germany)located at mid latitude, have been processed. The paper presents first results of investigations on GPS data recorded during a quiet period and under the presence of ionospheric irregularities. Further investigations are in progress.