Analysis and Processing of Vibration Interference Error of Oceanic Absolute Gravity Measurement Based on Variational Mode Decomposition

The atomic gravimeter is a very precise device ideal for ocean gravity field measurements. However, noise from various sources in the ocean environment, such as the waves, ship engines, and propeller systems, affects its accuracy. The noise interferes with the vibrations of the atomic gravimeter, which are non-linear and non-smooth. To address this issue, in this study, the variational mode decomposition (VMD) algorithm is proposed to analyze and process the vibration interference. First, the algorithm is used to analyze the amplitude and central frequency of vibration disturbances in dock, mooring, and navigation environments. Second, the measured vibration data and the gravimeter sensitivity function are convolved to obtain the total and each-frequency-band contribution of vibration noise. The findings indicate that, under navigation, the vibration noise is primarily concentrated in frequencies below 1 Hz, representing approximately 99.91% of the overall vibration noise spectrum. Additionally, a prominent peak is evident near 0.2 Hz, displaying an amplitude exceeding 5 Gal, believed to be associated with the rocking motion of the ship. Finally, despite employing vibration compensation, the intricate interference in shipborne gravity measurements leads to residual noise, with amplitudes reaching up to 10 mGal. To improve the quality of ocean absolute gravity data, the VMD algorithm is employed for efficient noise filtering. This research can help optimize the vibration isolation system of the atomic gravimeter and improve the signal-to-noise ratio (SNR) of the measurement data. This will make use of the atomic gravimeter for exploration of marine resources and global gravity field mapping.