Sea Technology

SEP 2012

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Tests and Upgrades for the East China Sea Seafloor Observatory Remote Observation System Monitors Oceanographic Data And Will Serve As Test Bed for New Long-Term Instrumentation By Huiping Xu Professor Yang Yu Ph.D. Student and Rufu Qin Lecturer School of Ocean and Earth Sciences Tongji University Shanghai, China T he East China Sea seafloor experimental observatory, which represents the first step in developing seafloor ob- servation systems in China, was installed near Xiaoqushan Island, 20 kilometers from Yanshan harbor, and began trial operations in April 2009. Upgrades began in October 2011 to transform it into an integrated observation station, with sup- port from the Shanghai Science and Technology Committee. The environmental baseline data for the East China Sea are inadequate, so more research is needed to understand the physical and biogeochemical processes that will help develop environmental prediction models, and spot and survey algal blooms. The observatory is located in an eel fishing area where the average water depth is 15 me- ters. The area is affected by an irregular semidi- urnal tide, which is not far from the deep wa- terway. The sediment is medium to fine sand, and the water is highly turbid because of close proximity to one of the Yangtze River's transpor- tation channels comprising mud and sand. The observatory consists of a submarine fiber- optic composite power cable more than 1 kilo- meter long and a special junction box, which provides power and communication signals to different instruments. Power is continuously sup- plied by the solar panels and batteries on top of the platform, which sits above the water. There are several power interfaces for the sensors: The location of the East China Sea Seafloor Obser- vatory at Xiaoqushan. 56 st / SEPTEMBER 2012 One is for 10-to-48-voltage DC input, and four are for 12-to- 24-voltage DC output, which can supply 10 watts each. The main functions of the junction box are power con- version and supply, data collection, coding, and remotely controlling and managing all equipment. The junction box is installed in a trawl preventer and has three kinds of wa- terproof plugs. It connects to a CTD sensor, turbidity sensor and an acoustic Doppler current profiler (ADCP). Instrumentation Testing and Initial Operations All oceanographic instrumentation designed for the long-term seafloor observatory must pass a series of tests: laboratory, indoor pool, lake water and, finally, a shallow- water experiment in the ocean. There are several lab, indoor and lake testing sites in China, but none are shallow-water test beds. The East China Sea Seafloor Observatory can be modified to serve this function; for instance, by modifying the junction box to handle any kind of sensor and upgrading the renewable power supply system.

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