A Method of Estimating Residual Bending Error in GNSS-RO Absolute TEC

Jaehee Chang, Andrew K. Sun, Jihyeok Park, Jiyun Lee, and Jade Morton

Peer Reviewed

Abstract:	Ionospheric refraction and dispersion effects induce residual bending error in the Total Electron Content (TEC) derived from Global Navigation Satellite System (GNSS) radio occultation (RO) measurements. This study proposes a practical method for the direct evaluation of residual bending error in the conventional absolute TEC retrieval. We derive the expression for the residual bending error in absolute TEC, by accounting for refraction residuals in both the carrier phase and pseudorange measurements. Two error components are identified: the altitudinally varying residual bending error from carrier phase TEC, and a constant bias from phase-to-pseudorange leveling. These errors are quantitatively assessed and analyzed by utilizing real observational data from COSMIC-2. Our analysis reveals that the residual bending error is predominantly influenced by vertical TEC gradients and can exceed the level of 10 TEC units (TECU). The findings underscore the need for estimating and correcting residual bending errors to improve the accuracy of absolute TEC retrievals, particularly under high solar activity conditions.
Published in:	Proceedings of the 2025 International Technical Meeting of The Institute of Navigation January 27 - 30, 2025 Hyatt Regency Long Beach Long Beach, California
Pages:	151 - 160
Cite this article:	Chang, Jaehee, Sun, Andrew K., Park, Jihyeok, Lee, Jiyun, Morton, Jade, "A Method of Estimating Residual Bending Error in GNSS-RO Absolute TEC," Proceedings of the 2025 International Technical Meeting of The Institute of Navigation, Long Beach, California, January 2025, pp. 151-160. https://doi.org/10.33012/2025.20005
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