295 / 2023-10-11 14:31:30

Improving the accuracy of GNSS-IR sea surface height measurement based on a novel ionospheric refraction correction optimization method

Ionospheric Refraction Correction Optimization Method,GNSS-IR,SNR,Sea Surface Height

Abstract

Global Navigation Satellite System Interferometry Reflection (GNSS-IR) is a passive remote sensing measurement technology that can obtain high-precision sea surface height data. However, the ionosphere affects the propagation path of GNSS signals, causing the satellite altitude angle to deviate from the true value, resulting in a decrease in the accuracy of GNSS-IR inversion of sea surface height. In response to this issue, this article studies the refraction phenomenon that occurs when GNSS signals pass through the ionosphere, and constructs an ionospheric refraction model that corrects altitude angle errors to improve the accuracy of GNSS-IR sea surface height measurement. Firstly, this article designs a new geometric model for GNSS signal propagation based on the traditional GNSS-IR method to weaken satellite altitude angle errors, and constructs a new ionospheric refraction correction optimization method (IRCOM) that helps improve the accuracy of sea surface altimetry. Secondly, the reliability of the IRCOM method was verified using raw observation data from 6 stations using IRCOM method and tidal level data from tide gauge stations. Inverting the inversion result sequences from 6 stations using IRCOM method and the tide level observation value sequences of the tide gauge station, and evaluate the accuracy of the inversion results. In the inversion results, the lowest RMSE is 7.41 cm (TRRG), the average RMSE is 14.67 cm, the highest correlation coefficient is 0.94 (TAR0), and the average correlation coefficient is 0.88, indicating that the IRCOM method can accurately invert sea surface height. Thirdly, in practical applications, the accuracy of sea surface hight inversion using traditional GNSS-IR and IRCOM methods was compared. The results showed that the RMSE of the IRCOM inversion sequences increased by a maximum of 6.63% (HUE1) compared to the GNSS-IR inversion sequences, with an average increase of 4.91%. The correlation coefficient of the IRCOM inversion sequences increased by a maximum of 20.9% (GOM1) compared to the GNSS-IR inversion sequences, with an average increase of 12.13%. The application results show that the IRCOM method has higher accuracy in sea surface height inversion compared to the GNSS-IR method. The IRCOM algorithm based on the ionospheric refraction model will provide an error optimization model and optimization method reference for future research on the influence of ionospheric refraction and improving the accuracy of sea surface height measurement.