Tide inversion based on GNSS-IR and analysis of barometric correlation under meteorological forcing

Accurate tidal level inversion and tidal response analysis are crucial for marine engineering construction, coastal safety, marine analysis, and climate analysis. In recent years, with the development and improvement of the GNSS, a Global Navigation Satellite System Interferometry Reflectometry (GNSS-IR) tidal level inversion method has been proposed. In the context of GNSS-IR tidal level inversion, research on meteorological forcing based on GNSS-IR, particularly the analysis of the correlation between air pressure and tidal level, has become an extended research area. Related studies have primarily focused on short-term response characteristics during storm surges, while the tidal level-air pressure response under other conditions has not been given much attention. Therefore, this paper aims to analyze the short-term and long-term correlation characteristics between tidal level and air pressure using data during four years from GNSS continuous tracking stations, based on the GNSS-IR tidal level inversion technique. First, considering the presence of significant errors and outliers in the GNSS-IR inversion values, robust estimation is introduced to perform multi-mode and multi-frequency GNSS-IR tidal level inversion fusion to improve accuracy. The results show that after removing height variation errors from the single-signal inversion, the root mean squared error (RMSE) is between 10～16 cm. After performing multi-mode and multi-frequency fusion of the single-signal inversion results, the RMSE reduces to 7～8 cm, improving accuracy by 30%. Next, cross-wavelet analysis of tidal levels and air pressure is conducted. The results reveal that tidal levels are influenced by the short-term meteorological forcing, especially during storm surges. The correlation between tidal level and air pressure is higher in spring and winter, while the correlation is less obvious in summer, which may be related to the local subtropical monsoon climate. Moreover, during extreme meteorological changes like storm surges, the tidal level-air pressure response is rapid. However, under meteorological changes influenced by climate, the tidal level shows a certain degree of response delay to air pressure.