Observations and transport theory analysis of low frequency, acoustic mode propagation in the Eastern North Pacific Ocean

Chandrayadula, Tarun K.; Colosi, John A.; Worcester, Peter F.; Dzieciuch, Matthew A.; Mercer, James A.; Andrew, Rex K.; Howe, Bruce M.

doi:10.1121/1.4818883

Cited by 14 publications

(8 citation statements)

References 28 publications

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“…The predictions were later verified by experimental observations from LOAPEX (Udovydchenkov et al, 2012). The work by Chandrayadula et al (2013) estimated mode energies and coherences from LOAPEX and compared them to transport theory predictions.…”

Section: Background On Broadband Mode Propagationmentioning

confidence: 65%

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Reduced rank models for travel time estimation of low order mode pulses

Chandrayadula

Wage

Worcester

et al. 2013

The Journal of the Acoustical Society of America

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Mode travel time estimation in the presence of internal waves (IWs) is a challenging problem. IWs perturb the sound speed, which results in travel time wander and mode scattering. A standard approach to travel time estimation is to pulse compress the broadband signal, pick the peak of the compressed time series, and average the peak time over multiple receptions to reduce variance. The peak-picking approach implicitly assumes there is a single strong arrival and does not perform well when there are multiple arrivals due to scattering. This article presents a statistical model for the scattered mode arrivals and uses the model to design improved travel time estimators. The model is based on an Empirical Orthogonal Function (EOF) analysis of the mode time series. Range-dependent simulations and data from the Long-range Ocean Acoustic Propagation Experiment (LOAPEX) indicate that the modes are represented by a small number of EOFs. The reduced-rank EOF model is used to construct a travel time estimator based on the Matched Subspace Detector (MSD). Analysis of simulation and experimental data show that the MSDs are more robust to IW scattering than peak picking. The simulation analysis also highlights how IWs affect the mode excitation by the source.

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Section: Background On Broadband Mode Propagationmentioning

confidence: 65%

“…In addition, CTD measurements were made at each source station. Refer to the work by Chandrayadula et al (2013) for the SSP estimates from the environmental measurements at the array and CTD profiles during LOAPEX.…”

Section: Low Rank Models For Modes In Loapex Datamentioning

confidence: 99%

Reduced rank models for travel time estimation of low order mode pulses

Chandrayadula

Wage

Worcester

et al. 2013

The Journal of the Acoustical Society of America

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“…Previously, theoretical estimates of the cross mode coherence matrix, mean intensity, and time and depth coherence have showed excellent agreement with Monte Carlo simulations in a variety of deep (Colosi and Morozov, 2009;, accepted for publication; Chandrayadula et al, 2012, accepted for publication) and shallow water scenarios at low frequency in the presence of linear and non-linear internal waves. Additionally, Thorsos et al (2004Thorsos et al ( , 2010 have developed a transport theory to explain the evolution of mode coherence by surface scattering mechanisms.…”

Section: Introductionmentioning

confidence: 93%

The effect of surface and linear internal waves on higher order acoustic moments in shallow water

Raghukumar¹,

Colosi²

2013

Proceedings of Meetings on Acoustics

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Acoustic fields in shallow water have a statistical nature due to complex, time-evolving sound speed fields and scattering from rough boundaries. Previously, coupled-mode transport theory [Raghukumar and Colosi (2012)] was applied to high frequency acoustic fluctuations in an environment typical of the Shallow Water 2006 (SW06) experiment on the New Jersey continental shelf. As a consequence of the strong adiabatic component in SW06 propagation, a hybrid approach was used to calculate mode coherences where mode energies from the DozierTappert approach were combined with adiabatic phase terms. Mode energies, coherences and acoustic intensities were examined and it was found that internal and surface waves preferentially couple low and high modes respectively. Here, we extend that study to include higher moments such as scintillation index and shift focus to modes that are coupled by both internal and surface waves. Oceanographic and sea surface measurements are used to constrain the internal wave and sea surface models. The relative importance of linear internal waves and surface scattering effects are studied using transport theory and Monte Carlo simulations.

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“…P. Worcester (SIO) and J. Colosi (NPS) are the guest editors for the special issue. A number of NPAL-related manuscripts have been submitted (Chandrayadula et al, 2012a, b;Colosi, 2012;Colosi et al, 2012a,b;Heaney et al, 2012;Henyey et al, 2012;. The special issue is expected to go to press in early 2013.…”

Section: Work Completedmentioning

confidence: 99%

North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

Worcester¹,

Cornuelle²,

Dzieciuch³

et al. 2012

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The North Pacific Acoustic Laboratory (NPAL) program is intended to improve our understanding of (i) the basic physics of low-frequency, broadband propagation in deep water, including the effects of oceanographic variability on signal stability and coherence, (ii) the structure of the ambient noise field in deep water at low frequencies, and (iii) the extent to which acoustic methods, together with other measurements and coupled with ocean modeling, can yield estimates of the time-evolving ocean state useful for acoustic predictions. The goal is to determine the fundamental limits to signal processing in deep water imposed by ocean processes, enabling advanced signal processing techniques to capitalize on the three-dimensional character of the sound and noise fields. OBJECTIVES A series of deep-water acoustic propagation experiments combining low-frequency, broadband sources with vertical and horizontal receiving arrays were conducted in the North Pacific Ocean during the period 1989 to 2005 as part of what is loosely referred to as the North Pacific Acoustic Laboratory Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

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Observations and transport theory analysis of low frequency, acoustic mode propagation in the Eastern North Pacific Ocean

Cited by 14 publications

References 28 publications

Reduced rank models for travel time estimation of low order mode pulses

Reduced rank models for travel time estimation of low order mode pulses

The effect of surface and linear internal waves on higher order acoustic moments in shallow water

North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

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