Real-time integrated sea surface height and wave monitoring using a GNSS buoy based on PPP-B2b service

High-precision real-time observation of sea surface height and wave parameters is essential for maritime safety, offshore engineering, disaster warning, and marine resource development. To overcome the high cost and operational complexity of in situ instruments and the limited spatiotemporal resolution of satellite remote sensing, this study proposes a global navigation satellite systems (GNSS) buoy method for integrated sea surface height and wave monitoring using the Beidou global navigation satellite system-3 (BDS-3) B2b service. Orbit, clock, and code bias corrections were used to build a dual-frequency ionosphere-free precise point positioning (PPP) model for precise buoy displacement estimation. Instantaneous sea surface elevation was derived from PPP-estimated buoy height after correcting for antenna geometry, buoy draft depth, and platform tilt, while wave parameters were retrieved using zero-crossing and spectral methods. Experiments included correction analysis, static and dynamic positioning tests, simulated wave tests, and a 24 h marine trial. In the marine experiment, the sea surface height root mean square error (RMSE) was 5.80 cm; significant wave height RMSEs were 3.72 and 4.33 cm; and average wave period RMSEs were 0.0916 and 0.0921 s for the zero-crossing and spectral methods, respectively. These results demonstrate the feasibility of integrated, real-time, and accurate sea surface height and wave monitoring with a PPP-B2b-based GNSS buoy.