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  • 1
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    Estimate of the bottom compressional wave speed profile in the northeastern South China Sea using "Sources of Opportunity" (2006)
    IEEE
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © IEEE, 2004. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Oceanic Engineering 29 (2004): 1231-1248, doi:10.1109/JOE.2004.834681.
    Description: The inversion of a broad-band "source of opportunity" signal for bottom geoacoustic parameters in the northeastern South China Sea (SCS) is presented, which supplements the towed source and chirp sonar bottom inversions that were performed as part of the Asian Seas International Acoustics Experiment (ASIAEX). This source of opportunity was most likely a "dynamite fishing" signal, which has sufficient low-frequency content (5-500 Hz) to make it complimentary to the somewhat higher frequency J-15-3 towed source (50-260 Hz) signals and the much higher frequency (1-10 kHz) chirp signals. This low frequency content will penetrate deeper into the bottom, thus extending the other inverse results. Localization of the source is discussed, using both a horizontal array for azimuthal steering and the "water wave" part of the pulse arrival for distance estimation. A linear broad-band inverse is performed, and three new variants of the broad-band inverse, based on: 1) the Airy phase; 2) the cutoff frequency; and 3) a range-dependent medium are presented. A multilayer model of the bottom compressional wave speed is obtained, and error estimates for this model are shown, both for the range-independent approximation to the waveguide and for the range-dependent waveguide. Directions for future research are discussed.
    Description: This work was supported by the Office of Naval Research under Grant N0 001 498-1-0413, Grant N00014-00-0931, and Grant N00014-01-0772 and by the National Science Council, Taiwan, R.O.C. under Grant NSC92-2611-E-002-005-CCS.
    Keywords: Broadband geoacoustic inversions ; Shallow water acoustics ; South China Sea
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Merging multiple-partial-depth data time series using objective empirical orthogonal function fitting (2011)
    IEEE
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    Publication Date: 2022-05-25
    Description: Author Posting. © IEEE, 2010. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Oceanic Engineering 35 (2010): 710-721, doi:10.1109/JOE.2010.2052875.
    Description: In this paper, a method for merging partial overlapping time series of ocean profiles into a single time series of profiles using empirical orthogonal function (EOF) decomposition with the objective analysis is presented. The method is used to handle internal waves passing two or more mooring locations from multiple directions, a situation where patterns of variability cannot be accounted for with a simple time lag. Data from one mooring are decomposed into linear combination of EOFs. Objective analysis using data from another mooring and these patterns is then used to build the necessary profile for merging the data, which is a linear combination of the EOFs. This method is applied to temperature data collected at a two vertical moorings in the 2006 New Jersey Shelf Shallow Water Experiment (SW06). Resulting profiles specify conditions for 35 days from sea surface to seafloor at a primary site and allow for reliable acoustic propagation modeling, mode decomposition, and beamforming.
    Description: This work was supported by the U.S. Office of Naval Research (ONR) under Grants N00014-04-1-0146 and N00014-05-1- 0482, theONRPostdoctoral FellowshipAward under Grant N00014-08-1-0204, and by E. Livingston and T. Pawluskiewicz. The work of P. F. J. Lermusiaux and P. J. Haley was supported by the ONR under Grants N00014-07-1-1061, N00014-07-1-0501, and N00014-08-1-1097 to the Massachusetts Institute of Technology.
    Keywords: 2006 Shallow Water Experiment (SW06) ; Empirical orthogonal functions (EOFs) ; Massachusetts Institute of Technology Multidisciplinary Simulation, Estimation, and Assimilation System (MIT-MSEAS) ocean modeling system ; Objective function fitting ; Oceanographic data merging
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Experimental and numerical studies of sound propagation over a submarine canyon northeast of Taiwan (2015)
    IEEE
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    Publication Date: 2022-05-25
    Description: Author Posting. © IEEE, 2015. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Ocean Engineering 40 (2015): 237-249, doi:10.1109/JOE.2013.2294291.
    Description: A study of sound propagation over a submarine canyon northeast of Taiwan was made using mobile acoustic sources during a joint ocean acoustic and physical oceanographic experiment in 2009. The acoustic signal levels (equivalently, transmission losses) are reported here, and numerical models of 3-D sound propagation are employed to explain the underlying physics. The data show a significant decrease in sound intensity as the source crossed over the canyon, and the numerical model provides a physical insight into this effect. In addition, the model also suggests that reflection from the canyon seabed causes 3-D sound focusing when the direction of propagation is along the canyon axis, which remains to be validated in a future experiment. Environmental uncertainties of water sound speed, bottom geoacoustic properties, and bathymetry are addressed, and the implications for sound propagation prediction in a complex submarine canyon environment are also discussed.
    Description: The Quantifying, Predicting and Exploiting (QPE) Uncertainty Initiative Experiment was supported jointly by the National Science Council, Taiwan, under Project NSC98-2623-E002-018-D and the U.S. Office of Naval Research (ONR) under Grant N00014-08-1-0763. The work of Y.-T. Lin was supported by the U.S. ONR under Grants N00014-10-1-0040 and N00014-13-1-0026. The work of T. F. Duda was supported by the U.S. ONR under Grant N00014-11-1-0194.
    Keywords: Acoustics ; Noise ; Numerical models ; Solid modeling ; Sonar equipment ; Underwater vehicles ; Vehicles
    Repository Name: Woods Hole Open Access Server
    Type: Article
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