Accuracy analysis of ground-based GNSS-R sea level monitoring based on multi GNSS and multi SNR

Abstract With the expansion of GNSS applications, Global Navigation Satellite System Reflectometry (GNSS-R) technology has become an essential means for sea level monitoring. The development and improvement of multi-GNSS have brought new opportunities for ground-based GNSS-R sea level inversion research. More than 100 satellites in orbit are expected to improve the time resolution and the reliability of inversion results significantly. And GNSS-R technology is an SNR-based inversion technology. With the opening of different frequency channels of various GNSS systems, more signal-to-noise ratio (SNR) types are available. Therefore, the research on the multi-GNSS sea level inversion was carried out, and the multi signals inversion accuracy was analyzed. Based on the 2017–2019 observation data of the MAYG on the east coast of Africa, the SNR of the navigation satellite signal is used to invert the sea level. The results show that the time resolution of multi-GNSS inversion is significantly improved, and the average number of inversions per day reaches 51. The time interval between the two inversion results is only 18.5 min, which is 2.4 times that of GPS alone. There is a high agreement between the inversion results and the measured values. The root mean square error (RMSE) of the two is 0.36 m, and the correlation coefficient (R) is 0.93. In particular, the BDS of 2019 is monitored. It is concluded that BDS2-GEO is not suitable for coastal altimetry, the monitoring accuracy of BDS2-MEO is better than that of BDS2-IGSO and the monitoring effect of BDS3-MEO is equal to that of BDS2-MEO.