ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006.

The ALOHA cabled observatory

F. K. Duennebier¹, M. D. Tremblay², D. Harris³, J. Jolly³, D. Copson³, J. Babinec³, W Doi³, R. Lukas⁴, D. M. Karl⁴

¹Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822

²Consultant, 1305 Gully Rd, Neptune, NJ 07753

³Engineering Support Facility, SOEST, University of Hawaii, Honolulu, HI 96822

⁴Department of Oceanography, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822

The Hawaii-4 electro-optical telecommunications cable passes within 12 km of Station ALOHA, a site where more than 15 years of oceanographic data have been collected on monthly cruises. This cable, retired from commercial service in 1994, will be utilized to provide power and communications to an oceanographic observatory at Station ALOHA. Installation of the observatory will proceed in two phases, with the cable being cut, terminated and moved to Station ALOHA in 2006, and a "Proof Module" will be installed to verify communications and provide initial data. The observatory proper will be installed on the ocean floor with the JASON II ROV in 2007. Communications for the ALOHA Cabled Observatory (ACO) will be supported by a novel protocol being developed for observatories utilizing SL-280 and SL-560 retired systems. More than 35,000 km of cable using these systems are installed in the Pacific basin alone. The new protocol will conform to the restrictions imposed by the original system, but will be far cheaper to implement than the original format. The initial implementation of this protocol at ACO will provide a 100 Mbit Ethernet channel for observatory use on one fiber pair. More than 1 kW of power will be provided to the observatory by the 1.6 A constant-current supply. Initial sensors on the proof module will include a hydrophone and absolute pressure sensor. The hydrophone, sampled at more than 60 ksamples/s, will have a bandwidth from 0.01 Hz to over 25 kHz. It will thus detect sounds from earthquakes and wave energy to whales and acoustic modems. The pressure sensor will detect tides and tsunami, When the main observatory is installed in 2007, experimenters will be able to connect sensors directly to the observatory on the ocean floor using wet-mateable connectors providing a data link and power to experiment systems, or acoustically, providing a relatively low-rate real-time data link from experiments.