FAQs about the ACO
What is the ACO?
The ALOHA Cabled Observatory (ACO) is a system of hardware and software that extends electric power and the Internet offshore, supporting sustained real-time observations in the deep ocean. The ACO is connected to Oahu, Hawaii by the HAW-4 telecommunications cable transferred to the project by AT&T in 2007.
Where is the ACO?
On June 6th, 2011, the ACO was deployed on the ocean bottom (depth ~ 5 km - 3 miles) at Station (ALOHA), 100 km (60 nautical miles) north of Oahu, Hawaii. Station ALOHA is the site of the long-term Hawaii Ocean Time-series (HOT) open ocean measurement program, visited by research vessels 10-12 times each year since October 1988.
What is there?
There are five modules that are connected together on the seafloor. The Junction Box is connected to the HAW-4 cable and to the Observatory module. Together, they supply 1200 watts of power and 100 Mbs of Ethernet communications to sensor systems on these two modules, and to the other three modules. The other modules are the Camera tripod, the AMM bottom node, and the TAAM mooring. Sensors provide live video of the ocean bottom around the ACO, sound from local and distant sources, currents, pressure, temperature, and salinity.
Why is the ACO there?
It is difficult to make sustained measurements in the deep ocean. Systems lowered on cables from research ships can use power from the ship, but ships (and people) cannot remain on station without reprovisioning. Systems that are moored in the ocean can make measurements for a longer period of time, but they are limited by the battery power that can be contained in pressure-resistant cases. Moored measurements are typically not available until the mooring is recovered a year or more after deployment. With a surface buoy and special subsurface cabling, moorings can transmit limited amounts of data by satellite to shore with relatively little delay. The ACO provides continuous power and fast two-way communications between shore and a variety of oceanographic instruments, allowing scientific research to be done continually. These capabilities allow scientists to modify sampling as we learn more about the ocean environment surrounding the ACO.
Why are sustained deep ocean measurements important?
Deep ocean measurements are important for testing ideas and numerical models of ocean circulation, climate and ecosystem behavior. Long-term changes in the deep ocean are particularly difficult to observe for technical reasons given above, and because short-term variations obscure them.