Space-Borne GNSS-R Ionospheric Delay Error Elimination by Optimal Spatial Filtering

Zhang, Qiuyang; Yang, Liu; Xia, Junming

doi:10.3390/s20195535

Cited by 5 publications

(2 citation statements)

References 18 publications

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“…Zhang Qiuyang analyzed the corresponding ionospheric delay measurement values in eight different regions of the world in the spaceborne GNSS-R experiment (Zhang et al, 2020a), and the results showed a meter-level accuracy. Among them, the ionospheric delay at a place close to this experimental site shows a fluctuation of about 6 m. In the experiment, Zhang Yun used the international reference ionospheric model to conduct ionospheric correction on the spaceborne GNSS-R altimetry experiment and the delay error was about 15 m (Zhang et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Correction of Atmospheric Delay Error of Airborne and Spaceborne GNSS-R Sea Surface Altimetry

Yan

Zheng

et al. 2022

Front. Earth Sci.

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Improving the measurement accuracy is a necessary condition for sea surface altimetry using the Global Navigation Satellite System Reflectometry (GNSS-R). The ionosphere and troposphere delay the transmission of satellite signals, which directly affect the measuring accuracy. The influence of the atmospheric environment on GNSS-R altimetry differs from different platforms. By analyzing and sorting out the altimetry data of airborne and spaceborne platforms, this paper studies the variation law of signal delay in the altimetry process from the point of view of mathematical geometry, which provides an example for improving the precision of GNSS-R altimetry measurements. Firstly, in order to facilitate data analysis, this paper constructed an altimetry model with the GNSS satellite position, specular reflection point position, receiver position as nodes, classified direct signals, and reflected signals. Secondly, calculate ionospheric puncture point coordinates , and interpolate GIM products provided by IGS using time and puncture point coordinates to obtain the VTEC value in the vertical direction of the puncture point, which was converted into the path direction STEC by projection function, the ionospheric delay of each part was obtained in this way. The tropospheric delay of each part is considered for the along-path component and the geometric component, the delay of along-path component was calculated by the UNB3m model, and the delay of geometric component was calculated by the equation provided by Nikolaidou (Nikolaidou et al., 2021). Thirdly, by comparing the sea surface height inversion results with or without atmospheric delay correction with the mean sea surface height provided by DTU15, the measurement accuracy with atmospheric delay correction is obviously improved. The study results of the influence of atmospheric delay on the altimetry experiments precision error of airborne and spaceborne platforms show that the error magnitude is consistent with the existing literature. In the airborne experiment, the influence of the ionosphere is negligible and the troposphere has sub-meter influence on altimetry results, among which the tropospheric along-path delay component occupies a high proportion. The geometric delay component has a high correlation with the satellite elevation angle and its influence on the measurement accuracy decreases with the elevation angle increase. The effect of this factor can be effectively weakened by setting a high satellite cutoff angle. In the spaceborne experiment, the effect of atmospheric delay on altimetry results fluctuates in the range of 3∼5 m when the satellite elevation angle is greater than 60°. In this paper, the method of calculating signal atmospheric delay through geometric relation to improving the measurement accuracy can provide an example for the atmospheric delay correction of GNSS-R ocean altimetry with high precision and spatial resolution in future research.

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Section: Discussionmentioning

confidence: 99%

Correction of Atmospheric Delay Error of Airborne and Spaceborne GNSS-R Sea Surface Altimetry

Yan

Zheng

et al. 2022

Front. Earth Sci.

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“…The geometric model of altimetry is shown in Figure 4, and the compensation of ionospheric delay and tropospheric delay also needs to be deeply studied. Zhang et al [123] investigated the effect of the ionosphere on spaceborne altimetry and analyzed the optimal value of spatial filtering to eliminate the ionospheric delay in altimetry. Cardellach et al [124] used the GA carrier phase of the GPS and Galileo signals from the CYGNSS data for altimetry, and the results showed that the measurement precision was 3 cm/4.1 cm (median/mean) at a sampling rate of 20 Hz.…”

Section: Spaceborne Sea Surface Altimetry and Land Topography 41 Sea ...mentioning

confidence: 99%

Spaceborne GNSS Reflectometry

Han

et al. 2022

Remote Sensing

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This article presents a review on spaceborne Global Navigation Satellite System Reflectometry (GNSS-R), which is an important part of GNSS-R technology and has attracted great attention from academia, industry and government agencies in recent years. Compared with ground-based and airborne GNSS-R approaches, spaceborne GNSS-R has a number of advantages, including wide coverage and the ability to sense medium- and large-scale phenomena such as ocean eddies, hurricanes and tsunamis. Since 2014, about seven satellite missions have been successfully conducted and a large number of spaceborne data were recorded. Accordingly, the data have been widely used to carry out a variety of studies for a range of useful applications, and significant research outcomes have been generated. This article provides an overview of these studies with a focus on the basic methods and techniques in the retrieval of a number of geophysical parameters and the detection of several objects. The challenges and future prospects of spaceborne GNSS-R are also addressed.

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Multi-GNSS Fusion Real-Time Kinematic Algorithm Based on Extended Kalman Filter Correction Model for Medium-Long Baselines

Xia

Ren

Yuan

et al. 2022

J. Shanghai Jiaotong Univ. (Sci.)

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Space-Borne GNSS-R Ionospheric Delay Error Elimination by Optimal Spatial Filtering

Cited by 5 publications

References 18 publications

Correction of Atmospheric Delay Error of Airborne and Spaceborne GNSS-R Sea Surface Altimetry

Correction of Atmospheric Delay Error of Airborne and Spaceborne GNSS-R Sea Surface Altimetry

Spaceborne GNSS Reflectometry

Multi-GNSS Fusion Real-Time Kinematic Algorithm Based on Extended Kalman Filter Correction Model for Medium-Long Baselines

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