Monterey Bay Aquarium Research Institute

The MARS Ocean Observatory Testbed

Chinese cabled observatory experiment

Testing ocean-observatory instruments to be deployed in the South China Sea
Frame grab of the secondary junction box for the Chinese experiment
This frame grab from ROV video shows the secondary junction box that serves as the hub for the Chinese experiment on the MARS ocean observatory. One of the cables from this junction box leads to the MARS science node. The other two cables lead to the two science experiment packages.

On April 21, 2011, four years and 16 days after MBARI and Tongji University signed an agreement to collaborate on ocean science efforts, the Chinese Ocean Observatory on MARS has become a reality. This experiment consists of three separate instrument packages connected by undersea data/power cables. The system is being deployed to help Chinese researchers develop and test key technologies that will be part of a long-term ocean observatory planned for the South China Sea.

The South China Sea observatory will be used to study marine ecosystems and biodiversity, tidal currents, earthquakes, and other seafloor phenomena. This experiment involves several Chineses research institutions and is supported by the Ministry of Science and Technology of the People's Republic of China. It was initially proposed by a group of researchers from Tongji University, led by Huaiyang Zhou.

The three instrument packages used in this experiment include a secondary junction box, a seawater chemistry monitoring system, and a system for monitoring currents and physical properties of seawater.

The secondary junction box

This secondary junction box is attached to the MARS science node by a 40-meter-long cable on the seafloor. The secondary junction box serves a function similar to that of the MARS science node. It includes 10 wet-mateable ports that can provide power and data connections to individual experiments via seconary seafloor cables.

The secondary junction box is used primarily for electrical-load monitoring and control (e.g. switching instruments on and off) and to provide a standardized clock time for all the instruments attached to its ports. It supplies power to instruments at 48 and 400 volts, and provides ground-fault and over-current protection. Most of the control software for the junction box resides on shore.

Frame grab of the seawater-chemistry monitoring system for the Chinese experiment
This frame grab from ROV video shows the seawater-chemistry package that is part of the Chinese experiment on the MARS ocean observatory. The coiled cable was unspooled and attached to the the secondary junction box.

The seawater-chemistry package

The seafloor-chemistry instrument package is connected by a seafloor cable to the secondary junction box. It includes an system to continuously measure concentrations of various anions in seawater. These anions include chloride, sulfate, and nitrate. A second system collects data from an AMT pH sensor, an oxygen optode, a chlorophyll fluorometer, a METS methane sensor, and an ISUS nitrate sensor.








Frame grab of the ocean-current monitoring system for the Chinese experiment
This frame grab from ROV video shows the ocean-current package that is part of the Chinese experiment on the MARS ocean observatory.The coiled cable was unspooled and attached to the the secondary junction box.

The ocean-current package

Like the seawater-chemistry package, the ocean-current package is hooked up to a port on the secondary junction box. It incorporates several devices for measuring ocean currents, including a 300 kHz RDI acoustic Doppler current profiler (ADCP), a SonTek/YSI acoustic Doppler velocitometer (ADV), and an SBE-19 CTD and SEACAT to measure temperature, salinity and water pressure. It also includes a transmissometer and optical backscatter instrument for measuring the turbidity of seawater.





Last updated: Jul. 25, 2012