Stability of Shipborne Quantum Gravimeter in Long-Term Continuous Marine Gravity Measurement

The shipborne quantum gravimeter (SQG) can directly measure absolute gravity values in marine environments. Compared to traditional relative gravimeters, they offer superior stability, require no external reference calibration, and can provide real-time absolute gravity values during long-term measurements. These advantages significantly enhance the efficiency of marine gravity field surveys and improve the quality of the data collected. Current research on marine quantum gravimeters primarily focuses on their short-term accuracy, while studies on their long-term performance remain limited. However, long-term measurement capability is crucial for marine gravity surveys. In this study, a self-developed shipborne quantum gravimeter was used for a 71-day continuous marine absolute gravity measurement campaign to evaluate its performance and long-term stability. Along repeated gravity survey line, the SQG demonstrated an internal coincidence accuracy of 0.42 mGal and an external coincidence accuracy of 0.39 mGal compared with a co-site relative gravimeter. The long-term stability of the SQG was evaluated using multiple moored offshore measurements and a cross-over gravity survey grid. Throughout the entire measurement period, the result before departure and after return differed from the gravity benchmarks by 0.06 mGal and 0.21 mGal, respectively, and a crossing point deviation of 0.76 mGal. These results indicate that the SQG exhibits excellent long-term stability for marine gravity measurements, providing strong supports for establishing offshore absolute gravity benchmarks and obtaining wide range marine gravity maps.