engleski

Vernal equinox TEC behaviour in correlation with GPS coordinates’ deviations

Satellite positioning signals’ ionospheric delay presents major single cause of GPS L1 performance degradation, caused by Total Electron Content (TEC) dynamics. Depending on nature of the particular event, TEC processes differ in several timescales, ranging from sudden solar events, solar cycle timescale and storm time periods. In long term, it is assumed that TEC behaviour is governed by Solar Ultra-Violet (UV) flux. TEC regularities have already been modelled, GPS ionospheric model being one of them. Characteristic TEC patterns have been observed in the area of Northern Adriatic (middle latitude region), being the motivation for the conducted research. Three vernal periods were analysed. Computed ionospheric delay was compared with the Klobuchar model. Although TEC showed gradual decrease following the solar cycle decline, several events caused its redistribution and peaking. Simultaneously, latitude and longitude coordinates’ deviations were calculated both with and without ionospheric model correction. Preliminary results showed measurable correlation between ionospheric delay and coordinate deviations’ residuals. Performance of the ionospheric model was discussed in terms of ionospheric delay description, pseudorange corrections and coordinate error mitigation. Modelled and unmodelled coordinate deviation patterns showed measurable correlation in quiet and unsettled periods. During the storm period, trends of patterns showed significant difference in observed values, as discussed. Results are outlined in the final chapter, together with planned continuation of the research.

total electron content, ionospheric model, coordinate deviation patterns, Northern Adriatic Region

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