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Wang Z.,Texas A&M University | DiMarco S.F.,Texas A&M University | Stossel M.M.,Texas A&M University | Zhang X.,Texas A&M University | And 2 more authors.
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2012

In June 2007, tropical Cyclone Gonu passed over an ocean observing system consisting of a deep autonomous mooring system in the northern Arabian Sea and a shallow cabled mooring system in the Sea of Oman. Gonu was the largest cyclone known to have occurred in the Arabian Sea and to strike the Arabian Peninsula. The instruments on the moorings continuously recorded water velocities, temperature, conductivity, pressure, dissolved oxygen (DO) and turbidity at multiple depths and at hourly intervals during the storm.Near-inertial oscillations at all moorings from thermocline to seafloor are coincident with the arrival of Gonu. Sub-inertial oscillations with periods of 2-10 day are recorded at the post-storm relaxation stage of Gonu, primarily in the thermocline of the deep array and at the onshore regions of the shallow array. These oscillations consist of warm, saline water masses, likely originating from the Persian Gulf. Prominent 12.7-day sub-inertial waves, measured at a station ~300. km offshore, are bottom-intensified and have characteristics of baroclinic topographically trapped waves. Theoretical results from a topographically trapped wave model are in a good agreement with the observed 12.7-day waves at Murray Ridge. The wavelength of the 12.7-day waves is about 590. km calculated from the dispersion relationship. Further analysis suggests that a resonant standing wave is responsible for trapping the 12.7-day wave energy inside the Sea of Oman basin. The observational results reported here are the first measurements of deepwater responses to a tropical cyclone in the Sea of Oman/Arabian Sea. Our study demonstrates the utility of sustained monitoring for studying the impact of extreme weather events on the ocean. © 2012 Elsevier Ltd. Source


Sano T.,National Museum of Nature and Science | Sakuyama T.,Japan Agency for Marine - Earth Science and Technology | Ingle S.,University of Southampton | Ingle S.,Lighthouse R and D Enterprises Inc. | And 2 more authors.
Geochemistry, Geophysics, Geosystems | Year: 2011

A continuous section from extrusive lavas, through sheeted dikes, and uppermost gabbros recovered from Integrated Ocean Drilling Program Hole 1256D provides important information regarding magma plumbing systems beneath superfast spreading ridges. Petrological examination demonstrates that a model of fractional crystallization from a magma of composition similar to one of the more primitive gabbros in a shallow (∼50-100 MPa) melt lens reasonably explains mineral and whole rock compositions of many lavas and dikes. Elevated concentrations of trace elements in some rocks appear to have resulted from mixing between primitive magma and highly evolved magma. About half of the dike samples have more evolved Fe-rich compositions than the extrusive lava samples. Magma densities of the Fe-rich dikes are a little higher (∼30 kg/m 3) than those of lavas, suggesting that these dike magmas would not reach the surface. Mineralogical investigations reveal that both lavas and dikes contain oscillatory zoned plagioclase xenocrysts, implying magma mixing caused by successive episodes of fractionation and magma replenishment in the melt lens. The plagioclase xenocrysts contain high-Anorthite sections [An: 100 × Ca/(Ca+Na) in mole percent] whose compositions are not in equilibrium with host liquids. The high-An sections were likely crystallized when primitive magmas with high CaO/Na2O were injected in the melt lens. Since the oscillatory zoned plagioclase generally forms crystal clots, they were probably accumulated in a mush zone. The petrographical examination favors a model suggesting that injection of primitive magma into the melt lens broke the mush zone and pushed out the oscillatory zoned plagioclase. Copyright 2011 by the American Geophysical Union. Source


Du Vall K.,Lighthouse R and D Enterprises Inc. | Ingle S.,Lighthouse R and D Enterprises Inc. | Snider J.,Lighthouse R and D Enterprises Inc. | Dimarco S.F.,Texas A&M University
OCEANS'11 - MTS/IEEE Kona, Program Book | Year: 2011

As the global population grows and becomes increasingly dependent on the ocean's resources, monitoring its physical and environmental conditions is more critical than ever: port authorities may wish to know tidal and current velocity information in order to schedule and guide shipping traffic; offshore drilling operators need real-time current velocities to determine the safety of their operations and to avoid costly delays; government ministries use knowledge of physical and biological conditions to manage and monitor the health of their fisheries resources and protect the people that use the ocean for recreation and income; coastal communities can greatly benefit from advance warning of approaching tsunamis; and coastal developers are often required to assess the impact of their developments on coastal water flow and quality. Ocean observation is clearly important to the modern world, yet many key regions of the ocean remain virtually uncharacterized and unmonitored. One such region is the northern Arabian Sea and the Sea of Oman. Since 2003, Lighthouse has worked to develop, install, and operate cutting-edge, real-time ocean observing and monitoring systems off the coast of the Sultanate of Oman. © 2011 MTS. Source


Dimarco S.F.,Texas A&M University | Wang Z.,Texas A&M University | Jochens A.,Texas A&M University | Stoessel M.,Texas A&M University | And 4 more authors.
Eos | Year: 2012

An ocean observatoryconsisting of a real-time, cabled array in the Sea of Oman and an internally recording, autonomous mooring array recently upgraded to a cabled array in the northern Arabian Seacelebrated more than 2500 days of continuous operation in July 2012. The observatory, which measures a range of properties, such as water current velocities, temperature, salinity, pressure, dissolved oxygen, and turbidity, is part of the Lighthouse Ocean Research Initiative (LORI) project [du Vall et al., 2011], which was designed as a pilot project and installed in 2005 in the region off Abu Bakara (Figures 1a and 1b). The initial goal of the project was to prove that an in situ, cabled ocean observatory can return high-quality scientific data on a real-time basis over longer time periods than conventional moored systems. That same year, an autonomous array was deployed off Ras al Hadd and on Murray Ridge in the Arabian Sea (Figure 1a). © 2012. American Geophysical Union. All Rights Reserved. Source


Ingle S.,Lighthouse R and D Enterprises Inc. | Belabbassi L.,Lighthouse R and D Enterprises Inc. | Du Vall K.,Lighthouse R and D Enterprises Inc. | Potter D.,Lighthouse R and D Enterprises Inc. | And 2 more authors.
OCEANS 2012 MTS/IEEE: Harnessing the Power of the Ocean | Year: 2012

In recent years, there have been several major initiatives to install fiber-optic cabled ocean observatories in the United States, Canada, Japan, and Europe. Lighthouse has operated a fiber-optic cabled ocean observing system off the northern coast of the Sultanate of Oman for seven years: the Lighthouse Ocean Research Initiative (LORI) I. In early 2010, a second cabled system was installed farther to the south, LORI II. LORI II is comprised of three, 2500-m-long moored arrays each equipped with eight Doppler current profilers and additional environmental sensors. The moorings sit along the 3000 m bathymetric line, so the uppermost current Doppler profiler uses a low frequency (75 kHz) to capture velocities and acoustic backscatter for the uppermost 500 m of the water column. Lighthouse had significant experience operating a cabled array in shallower water (<1350 m) and had deployed and recovered autonomous arrays from the same locations as the cabled LORI II instruments several times in the past and thus confidence was high the system would operate as installed. After deployment, the quality of the raw data was very good with nearly all of the installed sensors reporting; but by year two, communication with two of the moorings had been lost. The cause of the problem has been tentatively identified. Herein, we discuss the research, development, installation, and operation of LORI II over the past two and a half years, scientific results from LORI II data, and the lessons learned from seven years of successful operation of the LORI I cabled system, all of which will be incorporated in a new-and-improved, science-driven, cabled LORI II design. © 2012 IEEE. Source

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