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Application of SWACI products as ionospheric correction for single-point positioning: a comparative study

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In Global Navigation Satellite Systems (GNSS) using L-band frequencies, the ionosphere causes signal delays that correspond with link related range errors of up to 100 m. In a first order approximation the range error is proportional to the total electron content (TEC) of the ionosphere. Whereas this first order range error can be corrected in dual-frequency measurements by a linear combination of carrier phase- or code-ranges of both frequencies, single-frequency users need additional information to mitigate the ionospheric error. This information can be provided by TEC maps deduced from corresponding GNSS measurements or by ionospheric models. In this paper we discuss and compare different ionospheric correction methods for single-frequency users. The focus is on the comparison of the positioning quality using dual-frequency measurements, the Klobuchar model, the NeQuick model, the IGS TEC maps, the Neustrelitz TEC Model (NTCM-GL) and the reconstructed NTCM-GL TEC maps both provided via the ionosphere data service SWACI ( in near real-time. For that purpose, data from different locations covering several days in 2011 and 2012 are investigated, including periods of quiet and disturbed ionospheric conditions. In applying the NTCM-GL based corrections instead of the Klobuchar model, positioning accuracy improvements up to several meters have been found for the European region in dependence on the ionospheric conditions. Further in mid- and low-latitudes the NTCM-GL model provides results comparable to NeQuick during the considered time periods. Moreover, in regions with a dense GNSS ground station network the reconstructed NTCM-GL TEC maps are partly at the same level as the final IGS TEC maps.

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We would like to express our gratitude to the editors and reviewers for their remarks for the improvement of this paper. Additionally we thank IGS, SPIDR and WDC Kyoto for making available high quality GNSS and geo-related data. Further we would like to express our gratitude to the Aeronomy and Radiopropagation Laboratory of the Abdus Salam International Centre for Theoretical Physics Trieste/Italy providing NeQuick version 2.0.2 for scientific purposes. Finally, thanks to our colleagues of DLR’s Institute of Communications and Navigation maintaining provision of GNSS measurements via EVnet and to our colleagues of DLR’s Earth Observation Center supporting the SWACI service.

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Correspondence to David Minkwitz.

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Minkwitz, D., Gerzen, T., Wilken, V. et al. Application of SWACI products as ionospheric correction for single-point positioning: a comparative study. J Geod 88, 463–478 (2014).

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