A Double-Node Star Network Coastal Ocean Observatory

Abstract

A coastal cabled ocean observatory network with two observation nodes (first phase) along a 150-km electrical/optical submarine cable, supporting tens of scientific packages and up to hundreds of sensors, is under development in China, which is also China’s first attempt at constructing a long-term, large-scale ocean observatory network. Each node consists of one primary junction box (JB) and several secondary JBs that provide standardized ports for secondary JBs or scientific packages, respectively, through wet-mateable connections. The power system introduces bus topology for the primary nodes and star topology for all subnodes while the communication system adopts two separated and nonrepeated star topologies. In August 2013, the first primary node equipped with two scientific instruments deployed in the South China Sea 75 km offshore and at a 200-m depth. The node, however, failed in only 1 h due to a dry-mate connector breakdown and short caused by seawater, which prevented the high-voltage converter from properly starting up. Lessons learned from this failure and future plans are presented herein.