Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay
The slant path delay (SPD) exhibits “nonisotropy” in the horizontal direction, validated by ray tracing. This nonisotropy can cause decimeter-level errors in SPD, yet specific models and influencing factors remain under-researched. This study aims to quantify SPD nonisotropy wi...
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IEEE
2025-01-01
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| Series: | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing |
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| Online Access: | https://ieeexplore.ieee.org/document/10820978/ |
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| author | Ying Xu Hongzhan Zhou Fangzhao Zhang Zaozao Yang Ruozhou Wang |
| author_facet | Ying Xu Hongzhan Zhou Fangzhao Zhang Zaozao Yang Ruozhou Wang |
| author_sort | Ying Xu |
| collection | DOAJ |
| description | The slant path delay (SPD) exhibits “nonisotropy” in the horizontal direction, validated by ray tracing. This nonisotropy can cause decimeter-level errors in SPD, yet specific models and influencing factors remain under-researched. This study aims to quantify SPD nonisotropy with the nonisotropic value (ΔN), which represents the deviation between SPD and average SPD at corresponding elevations. We analyzed the spatiotemporal characteristics of nonisotropic SPD by estimating ΔN at 77 grid points (2019–2021, 1-day interval) and 804 grid points at different altitudes (2019–2021, 90-day interval). Using the IGG- scheme, we developed a nonisotropic SPD model considering azimuth continuity. We validated this model by incorporating VMF1 with horizontal gradient correction and VMF1 with horizontal gradient correction combined with the nonisotropic model into static PPP, tested at 16 IGS stations. Results indicate ΔN depends on time, latitude, altitude, elevation, and azimuth. The model categorizes SPD into positive anisotropy, undetermined isotropy, or negative anisotropy. For the 16 IGS stations, the nonisotropic model reduced the STD by 7.5%, 5.8%, and 2.8% in the E, N, and U directions, respectively, and decreased convergence time by 12.8%, 25.4%, and 1.4%. This confirms the model's effectiveness, offering a valuable tool for accurate SPD estimation and improved navigation under real atmospheric conditions. |
| format | Article |
| id | doaj-art-a2c599983adc413b882b3c9c1e10f198 |
| institution | Kabale University |
| issn | 1939-1404 2151-1535 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing |
| spelling | doaj-art-a2c599983adc413b882b3c9c1e10f1982025-01-28T00:00:24ZengIEEEIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing1939-14042151-15352025-01-01183879389210.1109/JSTARS.2025.352550110820978Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path DelayYing Xu0https://orcid.org/0009-0000-7622-9926Hongzhan Zhou1Fangzhao Zhang2https://orcid.org/0000-0002-2351-3568Zaozao Yang3Ruozhou Wang4College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, ChinaCollege of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, ChinaCollege of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, ChinaCollege of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, ChinaCollege of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, ChinaThe slant path delay (SPD) exhibits “nonisotropy” in the horizontal direction, validated by ray tracing. This nonisotropy can cause decimeter-level errors in SPD, yet specific models and influencing factors remain under-researched. This study aims to quantify SPD nonisotropy with the nonisotropic value (ΔN), which represents the deviation between SPD and average SPD at corresponding elevations. We analyzed the spatiotemporal characteristics of nonisotropic SPD by estimating ΔN at 77 grid points (2019–2021, 1-day interval) and 804 grid points at different altitudes (2019–2021, 90-day interval). Using the IGG- scheme, we developed a nonisotropic SPD model considering azimuth continuity. We validated this model by incorporating VMF1 with horizontal gradient correction and VMF1 with horizontal gradient correction combined with the nonisotropic model into static PPP, tested at 16 IGS stations. Results indicate ΔN depends on time, latitude, altitude, elevation, and azimuth. The model categorizes SPD into positive anisotropy, undetermined isotropy, or negative anisotropy. For the 16 IGS stations, the nonisotropic model reduced the STD by 7.5%, 5.8%, and 2.8% in the E, N, and U directions, respectively, and decreased convergence time by 12.8%, 25.4%, and 1.4%. This confirms the model's effectiveness, offering a valuable tool for accurate SPD estimation and improved navigation under real atmospheric conditions.https://ieeexplore.ieee.org/document/10820978/Global navigation satellite systems (GNSS) tropospheric delayhorizontal gradientsmapping functionnonisotropyray-tracingspatiotemporal properties |
| spellingShingle | Ying Xu Hongzhan Zhou Fangzhao Zhang Zaozao Yang Ruozhou Wang Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Global navigation satellite systems (GNSS) tropospheric delay horizontal gradients mapping function nonisotropy ray-tracing spatiotemporal properties |
| title | Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay |
| title_full | Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay |
| title_fullStr | Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay |
| title_full_unstemmed | Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay |
| title_short | Analysis of Spatiotemporal Properties and Modeling of the Nonisotropy of GNSS Tropospheric Slant Path Delay |
| title_sort | analysis of spatiotemporal properties and modeling of the nonisotropy of gnss tropospheric slant path delay |
| topic | Global navigation satellite systems (GNSS) tropospheric delay horizontal gradients mapping function nonisotropy ray-tracing spatiotemporal properties |
| url | https://ieeexplore.ieee.org/document/10820978/ |
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