Research on ocean-current-prediction-based virtual mooring strategy for the portable underwater profilers

The Argo Global Ocean Observing Network has remained the preeminent ocean observation network worldwide. Since the Argo buoys lack freedom of lateral movement, their wave-following working characteristics prevent them from completing the long-term observations in the designated sea area. Long-term monitoring of desig-nated waters is often required, for example, to study the impacts of seabed mining on the marine environment in the surrounding sea area. To solve this problem, a portable underwater profiler (PUP) that combines the func-tionalities of profiling buoys and underwater gliders was devised. The PUP employs a center of gravity adjust-ment mechanism utilizing the double-weight block approach, enabling the pitch angle adjustment within-90 degrees to 0 degrees. Remarkably, the PUP weighs only 11.25 kg, meeting the requirements for rapid deployment. Furthermore, the prediction method of the ocean current velocity was optimized by employing the full-depth-averaged ocean current velocity instead of the depth-averaged ocean current velocity. To ensure continuous observation oper-ations of the PUP within designated sea areas, a horizontal displacement correction strategy (HDCS) based on the virtual mooring concept is proposed. The effectiveness of the HDCS has been preliminarily validated through simulations and further confirmed through lake trials conducted in Qiandao Lake.