Deployment of mobile and real-time deep seafloor observatory

Mobility, expandability, replaceability, and real-time data transmission capability are key functions for the prospective observatory on seafloor to realize interdisciplinary in-situ continuous ocean observations with a variety of spatial and temporal scale coverage. Put this new approach on a firm footing, JAMSTEC developed a mobile seafloor observatory test bed called AOS (Adaptable Observation System) as an equipment fit in to the branching interface equipped in the latest submarine cable connected earthquake observation system. In 2001, the first AOS sea trial was carried out by JAMSTEC research vessels and underwater exploring system (such as towed vehicles and ROVs). The mobile observatory was successfully set up in the predetermined area which approximately 6km far from a branching interface in the backbone cable system. The components of AOS was recovered on land for inspect and maintenance after the end of first trial, and set it up again to another observation site in 2004. The evaluation of reliability of observatory and verification of major seafloor scientific instruments related technologies are being implemented in this trial. The engineering approach and observation technique demonstrated in these sea trials are essential to realize sophisticated 4-dimentional seafloor observation network in the future. This paper summarized the results of trials and discusses the approach to establish the solution for these engineering difficulties.