Development of an expendable current profiler and simulation of passive sources

A common approach to ocean current measurement is to use a motion-induced electric field; this is the basic principle of the expendable current profiler (XCP). However, existing studies into XCPs have not explored indoor simulations of the ocean current environment or the implementation of attitude correction in the hardware. The accuracy of XCPs can be verified via indoor experiments and is affected by the sinking attitude. Therefore, in this study, we develop an XCP to measure ocean information in real time, and we correct the data for different XCP sinking attitudes. Furthermore, we design electromagnetic-induction-based laboratory measurements of simulated dynamic ocean currents. The signals collected by the XCP are linearly related to the copper-plated-power-supply signal. The processed data are compared and the feasibility of extracting ocean current signals via electrodes is verified through laboratory simulations of XCPs. Furthermore, we performed marine experiments in the South China Sea; the results indicate that the system is stable and easy to use. We implemented an expendable conductivity-temperature-depth system at the same location; the curve trends measured by the two probes were consistent, and the maximum error was found to be 0.5 degrees C. We expect this work to improve the quality of ocean current measurements and subsequent monitoring capabilities.