Performance of GNSS Global Ionospheric Modeling Augmented by LEO Constellation

Abstract

The Low-Earth-Orbiting (LEO) satellite has a fast motion and thus contributes to rapid changes in satellite geometric distribution, which can effectively mitigate multipath effects and offer more available observations. Recently, some studies have investigated LEO-augmented Global Navigation Satellite System (GNSS) positioning and navigation. However, the study of LEO-augmented global ionospheric modeling was not yet available. In this paper, we present the performance and accuracy of global ionospheric model augmented by LEO constellation for the first time. Based on the three kinds of designed LEO constellations with 60, 96, and 192 satellite simulation data, the results show that LEO observations can expand the coverage and increase the density of ionospheric pierce points (IPPs). Meanwhile, the density of IPPs becomes higher with an increasing number of LEO satellites. When the cutoff elevation is set to 40°, the IPP distribution of GNSS+LEO is still better than that of GNSS-only at 10°. This way the cutoff elevation angle of the GNSS measurements can be increased, since the mapping function error and the multipath effects are reduced. Furthermore, the performances of global ionosphere maps based on the observations of GNSS-only and GNSS+LEO scenarios are evaluated. Compared with GNSS-only, the minimum and maximum bias can be reduced from −18.1 to −7.0 total electron content unit and from 12.6 to 6.4 total electron content unit, respectively, and the root-mean-square values with LEO constellations of 60, 96, and 192 satellites improve by 35.9%, 46.5%, and 50%, respectively. Key Points:• LEO satellite was utilized for global ionosphere modeling • LEO satellite observations can fill the gap of missing spatial and temporal values in existing GNSS-based ionospheric modeling • By combining LEO constellation and Multi-GNSS simulated datasets, higher accuracy and higher spatial model can be achieved

Electron Density Reconstruction by Ionospheric Tomography From the Combination of GNSS and Upcoming LEO Constellations

“…The detailed processing strategies of the constellation simulation and the ionospheric observation simulation have been introduced by Ren et al. (2020b). In this study, the ground‐based STEC observations of LEO and GNSS satellites are simulated by using the IRI‐2016 model, and the LEO satellite constellation is designed to consist of 192 polar‐orbiting satellites.…”

“…Due to the sparse and unevenly distributed GNSS‐tracking stations worldwide, however, conventional GIMs can only achieve a lower accuracy with a mean precision of 2–8 total electron content unit (TECU), especially in ocean areas (Chen et al., 2017; Hernández‐Pajares et al., 2017; Ren et al., 2020a, 2020b; Yuan and Ou, 2002). As a result, typical multisource data such as satellite altimetry, radio occultation from LEO satellites and Doppler Orbitography, and Radio‐positioning Integrated by Satellite instrument (DORIS) are integrated into GNSS data providing an increase of VTEC accuracy (Alizadeh et al., 2011; Chen et al., 2014; Dettmering et al., 2011; Hernández‐Pajares et al., 2020; Ren et al., 2020b, 2021; Todorova et al., 2008; Yao et al., 2018). The results showed that the accuracy of GIMs has been improved to make up the deficiencies of the existing GIMs by adding space‐based data.…”

“…Ren et al. (2020a, 2020b) also presented the GNSS‐based global ionospheric modeling results augmented by LEO satellite constellations for a 2D ionospheric model. Nevertheless, the study of the ionospheric electron density reconstruction by using GNSS and LEO satellite constellations data is not available currently.…”

LEO Constellation-Augmented Multi-GNSS for 3D Water Vapor Tomography

“…Once all the constellations are completed, the number of available LEO satellites would be in the tens of thousands [20]. Some of these LEO constellations can provide navigation augmentation services, which can contribute to precision point position (PPP) ambiguity solving, shorten convergence time [21,22], and improve the accuracy of the ionospheric model [23,24]. Compared with GNSS, LEO satellites have some of the following characteristics: lower orbits, stronger signals, less interference, longer trajectories across the sky in the same time, and faster geometry changes.…”

Assessment and Validation of Three Ionospheric Models (IRI‐2016, NeQuick2, and IGS‐GIM) From 2002 to 2018

“…With the increasing number of Low Earth orbit (LEO) satellites in the near future, 3D ionosphere model will play an essential role in GNSS global ionospheric modeling augmented by LEO satellites (Ren et al, 2020). The increasing demand for ionospheric and space geodetic applications makes it of particular importance to assess the performance of the 3D ionospheric models from different aspects for the long‐term comprehensively.…”