(OMSFC). These data form the basis for environmental assessments to measure seasonal variations associated with monsoon perturbation. The array was positioned to intercept signals from any release from the Arabian Gulf shipping traffic, as well as to monitor parameters essential to water quality assessments meaningful to fisheries (salinity, temperature, oxygen, etc.). It provides detailed information on water motion and density; both are critical to the modeling and prediction of spill behavior. Four seabed nodes are connected to base arrays containing the full suite of sensors mentioned above. A fiber optic cable connects the nodes, and it leaves the water at Abu Bakara, where the data collection, storage and early analyses on the health and performance of the system is constantly monitored. The cabled observatory thus extends about 60 km northeast across the Al Batinah coastal shelf, providing real-time ocean data, which monitors the health and potential threats from natural and possible anthropogenic causes. Closest to shore, designated 1-1, is a stand-alone seabed measurement system sited at a depth of about 65 m. Since the current speed and direction are acoustically measured in thin (2 m Figure 2. Schematic profile of deployment elements. Red boxes are insonified layers of the water column yielding thick) "layers" (cells, or "bins") to a height of 50 m above current speed and direction data. each sensor, 1-1 is monitoring currents in nearly all the water column. The other seven sensor packages are shown in the profile of deployments in Figure 2, and the 50-m in the Northern Arabian Sea. Data from all four layer shown in the water column above each package is autonomous moorings are retrieved annually. sampled for current speed and direction in the red box Cabled seabed observatories are generally considered positioned above the meters (See Figure 3 for an example prototype installations and as such they have not been of current velocity data). Thus array 4-1 and its moored without problems. The Al Batinah deployment has been instruments at two levels above the seabed (and likewise no exception. Electronic systems in the sea are always subthe single moorings above 2-1 and 3-1) provide a real- ject to numerous hazards, and the Batinah systems have time snapshot of water motion in the overlying shelf seen sensor failures, power interruptions and mechanical waters. problems related to complex instruments operating conThe base of each array is housed in a trawl-proof cage, tinuously hundreds of feet below the surface. The cabled which protects all sensors from fishing damage while act- observatory is a prototype, which through troubleshooting as an instrumented tether for the deeper buoyed ing, analyses and repair provide confidence in continued arrays. They weigh about 37,000 pounds (~17,000 kilos) and improved data collection. and are designed to withstand any dragging or other disContinuing interest in the Sultanate of Oman for ocean placement of observatory components. measurements and monitoring for public safety is leading To increase the accuracy of numeric modeling, three to its critical role in developing the ongoing Indian Ocean autonomous moorings were set 60 nm off of Oman's Tsunami Warning System (IOTWS). As a result of the Cape Ras Al Hadd. These arrays are positioned to moni- December 2004 tsunami, 27 nations have joined the tor the currents coming out of the Arabian Gulf, currents IOTWS under a multinational program being directed by coming up the coast from the Red Sea, and within the the Intergovernmental Oceanographic Commission convergence area off the Cape. Another stand-alone array under the United Nations Education, Science and is set off the South Eastern Margin of the Murray Ridge Cultural Organization. www.seadiscovery.com Marine Technology Reporter 35
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