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  • 1
    Online Resource
    Online Resource
    American Meteorological Society ; 1996
    In:  Journal of Physical Oceanography Vol. 26, No. 12 ( 1996-12), p. 2735-2747
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 26, No. 12 ( 1996-12), p. 2735-2747
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 1996
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 2
    Online Resource
    Online Resource
    American Meteorological Society ; 2016
    In:  Journal of Physical Oceanography Vol. 46, No. 12 ( 2016-12), p. 3661-3679
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 46, No. 12 ( 2016-12), p. 3661-3679
    Abstract: A hydrostatic, coupled-mode, shallow-water model (CSW) is described and used to diagnose and simulate tidal dynamics in the greater Mid-Atlantic Bight region. The reduced-physics model incorporates realistic stratification and topography, internal tide forcing from a priori estimates of the surface tide, and advection terms that describe first-order interactions of internal tides with slowly varying mean flow and mean buoyancy fields and their respective shear. The model is validated via comparisons with semianalytic models and nonlinear primitive equation models in several idealized and realistic simulations that include internal tide interactions with topography and mean flows. Then, 24 simulations of internal tide generation and propagation in the greater Mid-Atlantic Bight region are used to diagnose significant internal tide interactions with the Gulf Stream. The simulations indicate that locally generated mode-one internal tides refract and/or reflect at the Gulf Stream. The redirected internal tides often reappear at the shelf break, where their onshore energy fluxes are intermittent (i.e., noncoherent with surface tide) because meanders in the Gulf Stream alter their precise location, phase, and amplitude. These results provide an explanation for anomalous onshore energy fluxes that were previously observed at the New Jersey shelf break and linked to the irregular generation of nonlinear internal waves.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2016
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2019
    In:  The Journal of the Acoustical Society of America Vol. 146, No. 3 ( 2019-09-01), p. 1996-2015
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 146, No. 3 ( 2019-09-01), p. 1996-2015
    Abstract: Three-dimensional (3D) underwater sound field computations have been used for a few decades to understand sound propagation effects above sloped seabeds and in areas with strong 3D temperature and salinity variations. For an approximate simulation of effects in nature, the necessary 3D sound-speed field can be made from snapshots of temperature and salinity from an operational data-driven regional ocean model. However, these models invariably have resolution constraints and physics approximations that exclude features that can have strong effects on acoustics, example features being strong submesoscale fronts and nonhydrostatic nonlinear internal waves (NNIWs). Here, work to predict NNIW fields to improve 3D acoustic forecasts using an NNIW model nested in a tide-inclusive data-assimilating regional model is reported. The work was initiated under the Integrated Ocean Dynamics and Acoustics project. The project investigated ocean dynamical processes that affect important details of sound-propagation, with a focus on those with strong intermittency (high kurtosis) that are challenging to predict deterministically. Strong internal tides and NNIW are two such phenomena, with the former being precursors to NNIW, often feeding energy to them. Successful aspects of the modeling are reported along with weaknesses and unresolved issues identified in the course of the work.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2019
    detail.hit.zdb_id: 1461063-2
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2016
    In:  Ocean Dynamics Vol. 66, No. 10 ( 2016-10), p. 1209-1229
    In: Ocean Dynamics, Springer Science and Business Media LLC, Vol. 66, No. 10 ( 2016-10), p. 1209-1229
    Type of Medium: Online Resource
    ISSN: 1616-7341 , 1616-7228
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
    detail.hit.zdb_id: 2063267-8
    detail.hit.zdb_id: 201122-0
    SSG: 14
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  • 5
    Online Resource
    Online Resource
    Institute of Electrical and Electronics Engineers (IEEE) ; 2010
    In:  IEEE Journal of Oceanic Engineering Vol. 35, No. 4 ( 2010-10), p. 710-721
    In: IEEE Journal of Oceanic Engineering, Institute of Electrical and Electronics Engineers (IEEE), Vol. 35, No. 4 ( 2010-10), p. 710-721
    Type of Medium: Online Resource
    ISSN: 0364-9059 , 1558-1691
    Language: Unknown
    Publisher: Institute of Electrical and Electronics Engineers (IEEE)
    Publication Date: 2010
    detail.hit.zdb_id: 2025369-2
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  • 6
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2009
    In:  The Journal of the Acoustical Society of America Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2305-2305
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2305-2305
    Abstract: Acousticians need a fully four-dimensional (4-D) coastal oceanography model that can provide the soundspeed field down to the internal wave scale. While mesoscale ocean models exist, given the complexities of a full primitive equation (i.e., nonlinear), non-hydrostatic, fine-scale model including internal waves, it may be a decade or more before such a model is available from the mainstream oceanographic community. We pose the possibility of creating a usable approximate 4-D ocean model based on a combination of a powerful acoustics technique, the Weinberg–Burridge vertical modes and horizontal ray solution to the wave equation, and existing primitive-equation ocean models and two-dimensional nonlinear wave equations. In our technique, the local ocean internal wave modes are found, creating a horizontal index of refraction grid for internal-tide ray tracing from identified source points. Broadband internal waves are propagated along the trajectories using the KdV or other appropriate nonlinear wave equation, with internal-tide initialization and interpolation between trajectories. An ocean numerical model with good bathymetry provides the source distribution as well as buoyancy frequency profiles and current profiles, necessary inputs for the internal wave modes and propagation. The initial design for this model as well as examples of its usages for ocean acoustics are presented.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2009
    detail.hit.zdb_id: 1461063-2
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  • 7
    In: Communications Earth & Environment, Springer Science and Business Media LLC, Vol. 2, No. 1 ( 2021-07-27)
    Abstract: Deep-sea polymetallic nodule mining research activity has substantially increased in recent years, but the expected level of environmental impact is still being established. One environmental concern is the discharge of a sediment plume into the midwater column. We performed a dedicated field study using sediment from the Clarion Clipperton Fracture Zone. The plume was monitored and tracked using both established and novel instrumentation, including acoustic and turbulence measurements. Our field studies reveal that modeling can reliably predict the properties of a midwater plume in the vicinity of the discharge and that sediment aggregation effects are not significant. The plume model is used to drive a numerical simulation of a commercial-scale operation in the Clarion Clipperton Fracture Zone. Key takeaways are that the scale of impact of the plume is notably influenced by the values of environmentally acceptable threshold levels, the quantity of discharged sediment, and the turbulent diffusivity in the Clarion Clipperton Fracture Zone.
    Type of Medium: Online Resource
    ISSN: 2662-4435
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 3037243-4
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  • 8
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2509-2509
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2509-2509
    Abstract: The value of acoustic propagation modeling using water-column sound-speed fields from computational physical oceanographic models is well established. With a proper investment in measurements and models it is now possible to make predictions of real-time and future acoustic effects of mesoscale eddies and other structures. This capability depends on properly incorporating data from satellite and in situ instruments into data-assimilative models. Many challenges remain, however. First, mesoscale feature uncertainties are high when data are scarce. Second, models do not fully handle gravity waves (internal and surface) and submesoscale features. The present utility of models is high despite these remaining challenges. For example, models running open-loop or with partial boundary condition and internal constraints will generate realistic fields for acoustics studies that have goals other than sound-field prediction. Recent analyzes of the sound propagation effects, at 50–1000 Hz, of internal waves, fronts, and canyons show that realism can improve studies of transmission loss uncertainty and fluctuation characteristics. As examples, internal-wave curvature affects acoustic beam generation and horizontal interference patterns, and internal-tide amplitude and direction affect shallow-water acoustic mode wavenumbers and attenuation parameters. Acoustic fluctuation effects computed with three-dimensional (3D) acoustic modeling through internal-wave permitting ocean models will be presented.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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  • 9
    In: Journal of Field Robotics, Wiley, Vol. 24, No. 6 ( 2007-06), p. 437-448
    Abstract: The problem of how to optimally deploy a suite of sensors to estimate the oceanographic environment is addressed. An optimal way to estimate (nowcast) and predict (forecast) the ocean environment is to assimilate measurements from dynamic and uncertain regions into a dynamical ocean model. In order to determine the sensor deployment strategy that optimally samples the regions of uncertainty, a Genetic Algorithm (GA) approach is presented. The scalar cost function is defined as a weighted combination of a sensor suite's sampling of the ocean variability, ocean dynamics, transmission loss sensitivity, modeled temperature uncertainty (and others). The benefit of the GA approach is that the user can determine “optimal” via a weighting of constituent cost functions, which can include ocean dynamics, acoustics, cost, time, etc. A numerical example with three gliders, two powered AUVs, and three moorings is presented to illustrate the optimization approach in the complex shelfbreak region south of New England. © 2007 Wiley Periodicals, Inc.
    Type of Medium: Online Resource
    ISSN: 1556-4959 , 1556-4967
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2007
    detail.hit.zdb_id: 2224269-7
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  • 10
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2009
    In:  The Journal of the Acoustical Society of America Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2304-2304
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2304-2304
    Abstract: The dynamic shelfbreak front commonly observed in the continental shelf area has significant impact on underwater sound propagation. Analytical study with an idealized front model has shown that combining inshore refraction from the front and offshore refraction on the sloping shelf, long-range propagating sound on the continental shelf will be trapped by the front and form “whispering gallery” modes on the inshore side of the front. In this paper, numerical propagation simulations with three-dimensional normal mode and parabolic approximation methods are implemented to investigate the acoustic impact of a nearly realistic front model. This front model results from the MIT Multidisciplinary Simulation, Estimation, and Assimilation System which assimilated the field measurements collected during the New Jersey Shelf Shallow Water 2006 experiment. Since the front model captures very well the temporal and spatial variability of the shelfbreak frontal system in the field, the numerical propagation simulations presented here are fairly realistic. Horizontal sound refraction due to the shelfbreak front and (sub)-mesoscale eddies are observed, and causes part of long-range propagating sound energy to be trapped on the shelf area.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2009
    detail.hit.zdb_id: 1461063-2
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