Performance of various predicted GNSS global ionospheric maps relative to GPS and JASON TEC data
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When using predicted total electron content (TEC) products to generate preliminary real-time global ionospheric maps (GIMs), validation of these ionospheric predicted products is essential. In this study, we evaluate the accuracy of five predicted GIMs, provided by the international GNSS service (IGS), over continental and oceanic regions during the period from September 2009 to September 2015. Over continental regions, the GPS TEC data collected from 41 IGS continuous tracking stations are used as a reference data set. Over oceanic regions, the TEC data from the JASON altimeter are used for comparison. An initial performance comparison between the IGS combined final GIM product and the predicted GIMs is also included in this study. The evaluation results show that the predicted GIMs produced by CODE outperform the other predicted GIMs for all three validation results. The accuracy of the 1-day predicted GIMs, produced by the IGS associate analysis centers (IAACs), is higher than that of the 2-day predicted GIMs. Compared to the 2-day UPC predicted GIMs, the 2-day ESA predicted GIMs are observed to have slightly worse performances over ocean regions and better positioning performances over continental regions.
KeywordsGNSS Total electron content (TEC) Predicted global ionospheric maps (GIMs) JASON altimeter
Many thanks are due to the IGS for providing access to the ionospheric GIM products. This work was supported by the National Key Research Program of China “Collaborative Precision Positioning Project” (No. 2016YFB0501900), China Natural Science Funds (No. 41231064, 41674022, 41704038, 41574033 and 41621091), and the State Key Laboratory of Geodesy and Earth’s Dynamics (SKLGED2017-3-1-EZ).
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