Moorings provide oceanographers the means to deploy sensors at fixed depths between the seafloor and the sea surface and to deploy packages that provide vertical profiles at one location by moving up and down along the mooring line/cable or by winching themselves up and down from their point of attachment to the mooring.
An oceanographic mooring is anchored to the seafloor by one of more mooring lines extending upward from one or more anchors to one or more buoyant floats located in the water column or at the sea surface. The mooring line may consist of plastic-jacketed steel wire rope, synthetic line, or electromechanical fiber optic cable with copper conductors. These capable and proven oceanographic platforms are used throughout the OOI.
Types of Moorings
Flanking Moorings are subsurface moorings located at the Global Irminger Sea and Station Papa Arrays, which contain instruments fixed at specific depths along the mooring riser. Flotation spheres for subsurface moorings are located below the sea surface. As they have no surface expression, these moorings communicate and send data to shore via an acoustic link to nearby gliders.
Profiler Moorings are a type of mooring that contain instruments fixed to Profilers that move up and down through the water column. Profilers either track along the mooring riser (wire-following profilers), or include a winch that pays out line of fiber optic cable allowing the profiler, in some cases called the science pod, to move up and down through the water (e.g. Shallow Profilers on the Regional Cabled Array) and in some cases pierce the surface (e.g. Surface Piercing Profilers on the Coastal Array). Instruments also are attached directly to the mooring riser or affixed to an underwater platform on these moorings. Data from RCA moorings are transmitted to shore in real-time via the fiber optic cables. A subset of data for uncabled moorings with surface expressions are transmitted via satellite, however, most of the uncabled data are downloaded following recovery of the moorings each year. More details on profilers can be found here.
A Surface Mooring is a type of mooring that contains a surface buoy floating on the sea surface and instruments located at fixed depths through the water column. The surface buoy provides a platform on which to secure surface instruments, allowing for the collection of data in the air and in the water. Surface Moorings have solar and wind power-generation capabilities, as well as antennas for satellite and line-of-sight communications.
Surface Moorings are located both on Coastal and Global Arrays. Surface Moorings on Coastal Arrays use technology, such as stretch hoses, to allow the mooring to withstand large tidal fluctuations and rough seas while powering/communicating with instruments on the seabed. Global Surface Moorings are designed to withstand rough sea conditions associated with high latitudes and deep, open ocean sites. Surface Moorings are paired with Profiler Moorings in order to allow the comparison of time series data at a few discrete depths within the water column, with high vertical resolution profiler data.