Mooring systems for time-series observation for biogeochemistry in the northwestern North Pacific: design, preparation and mooring work

抄録

For the better understanding of carbon cycle in the northwestern North Pacific where rough sea condition frequently refuses oceanographic observation by research vessel, time-series observation for the biogeochemistry with mooring system has been requested strongly. Mutsu Institute for Oceanography (MIO) challenged to deploy the mooring system that is anchored on the sea floor at > 5,000 m depth and its top with automatic instruments is located in the euphotic layer, upper 30–50 m. In order to enable this deployment, behaviors of mooring system such as tilt and depth for instruments during deployment and observation were simulated, and precise lengths of wire and nylon ropes used for mooring systems were measured under the mooring tension on land. Based on these procedures, two types mooring systems were deployed at stations K-1 (51°N, 165°E) and K-3 (39°N, 160°E) in October 2002 and recovered in November 2003. Mooring systems were successfully deployed within 300 m from a "target" points and depths of top of mooring systems could be located between 40–60 m for K-1 mooring and 50–70 m for K-3 mooring as we designed except high current period.