Anomalous 18.61-Year Nodal Cycles in the Gulf of Tonkin Revealed by Tide Gauges and Satellite Altimeter Records

Understanding nodal tidal characteristics is essential for accurate long-term prediction. Observational evolution of tides mainly based on tide gauge records in coastal areas which are limited time and space, thus impeding coherent determinations basin-wide patterns variability. In this paper, we indicate the potential satellite altimeter data to investigate 18.61-year modulations main constituents Gulf Tonkin. Three gauges multi-source observations (TOPEX/Poseidon, Jason1, Jason2, Jason3) revealed that cycles amplitudes have noticeable deviations from equilibrium theory general, M2 N2 anomalously larger than theoretical values while K2, K1, O1 noticeably smaller values. Compared point-based gauges, can provide features constituents. Although overlapping geographical blocks applied eliminate effect alias originated long-period sampling intervals, estimation minor still questionable. Nevertheless, methods described here a strong foundation future research time-varying dynamics using combination data.