The Impact of Different Ocean Tide Loading Models on GNSS Estimated Zenith Tropospheric Delay Using Precise Point Positioning Technique

Abstract

Global navigation satellite systems (GNSSs) have become an important tool to derive atmospheric products, such as the total zenith tropospheric delay (ZTD) and precipitable water vapor (PWV) for weather and climate studies. The ocean tide loading (OTL) effect is one of the primary errors that affects the accuracy of GNSS-derived ZTD/PWV, which means the study and choice of the OTL model is an important issue for high-accuracy ZTD estimation. In this study, GNSS data from 1 January 2019 to 31 January 2019 are processed using precise point positioning (PPP) at globally distributed stations. The performance of seven widely used global OTL models is assessed and their impact on the GNSS-derived ZTD is investigated by comparing them against the ZTD calculated from co-located radiosonde observations. The results indicate that the inclusion or exclusion of the OTL effect will lead to a difference in ZTD of up to 3–15 mm for island stations, and up to 1–2 mm for inland stations. The difference of the ZTD determined with different OTL models is quite small, with a root-mean-square (RMS) value below 1.5 mm at most stations. The comparison between the GNSS-derived ZTD and the radiosonde-derived ZTD indicates that the adoption of OTL models can improve the accuracy of GNSS-derived ZTD. The results also indicate that the adoption of a smaller cutoff elevation, e.g., 3° or 7°, can significantly reduce the difference between the ZTDs determined by GNSS and radiosonde, when compared against a 15° cutoff elevation. Compared to the radiosonde-derived ZTD, the RMS error of GNSS-derived ZTD is approximately 25–35 mm at a cutoff elevation of 15°, and 15–25 mm when the cutoff elevation is set to 3°.

Tropospheric Delay Correction of VLBI Stations for the Real‐Time Trajectory Determination of the Chang'E‐5 Spacecraft

“…Additionally, ray‐tracing (Hobiger et al., 2008) through the numerical weather model is adopted when extreme accuracy is required (Duev et al., 2012; Nafisi et al., 2012). Meanwhile, the ground‐based Global Positioning System (GPS) technique is available to estimate different parameters to characterize tropospheric variability (H. Li et al., 2014; Kačmařík et al., 2017; Mao et al., 2021; S. Li et al., 2021; Zhang et al., 2020). Tropospheric delay has been corrected using GPS technique in the postprocessing VLBI technique of the SELENE satellite, with the Niell mapping function (Liu et al., 2009; Niell, 1996).…”