Ocean Current Sensing Using Integrated Load Cell in the Mooring Line of a Data Buoy

In this article, an attempt has been made to estimate surface ocean current using an integrated load cell in the mooring line of a data buoy. The conventional moored data buoy system uses the Doppler-based single-point current meter (SPCM) for the measurement of surface current speed and direction. The SPCM is expensive and requires higher power, and the performance is affected by the biofouling. The proposed technique solves these challenges by using a load cell as a sensing device which is comparably less expensive and requires less power and the sensor performance is not affected by biofouling. The numerical analysis was carried out by finite-element method using OrcaFlex software. The study reveals that the ocean currents have a significant contribution to the effective mooring load over wind and wave and the errors associated with wind and wave are negligible. It is also observed that the mooring load is maximum near the surface buoy. Hence, the load cell is introduced close to the buoy on the mooring line. From the mooring load cell data collected from a buoy each in the Arabian Sea and the Bay of Bengal, it is found that there is a very strong correlation with surface currents obtained from reference SPCM. It has been observed that during the cyclonic events named Amphan, the correlation coefficient (CC) is found to be as high as 0.95. For the system tested, the threshold current is 0.24 m/s which is necessary to sense current from effective mooring load measurement.