| New Bottom Roughness Calculation from Multibeam Echo Sounders for Mine Warfare |
Sep 2012 |
80 pages |
| Authors:
Patrick J Earls; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
 | Bottom roughness has a significant effect on acoustic backscattering on the ocean bottom. Sonar systems rely on backscattering and shadows to detect objects lying on the seafloor. The seafloor is rather complex, and it can include craters, gullies, seaweed, rocks, sand ridges, tall obstructions, deep holes, and sloping regions. Underwater mines can be hidden near these seafloor features, making detection more difficult. High-resolution (1 m x 1 m) seafloor data ... |
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| The Study of Upper Ocean Stratification that Controls Propagation of Internal Tidal Bores in Coastal Areas |
Jun 2012 |
85 pages |
| Authors:
Kathryn A Yanez; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| Coastal ocean stratification and optical properties have been analyzed over a month period from Moss Landing to Monterey Bay in Monterey, California, during October 2011. This research utilized measurements from four different observing systems: the Tethys long-range propeller-driven autonomous underwater vehicle (AUV); a Spray glider AUV; a SeaHorse moored profiler; and a thermistor chain to evaluate changes in conductivity, pressure, temperature, salinity, and optics over a 4-week time period. Each ... |
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| Theory and Modeling of Internal Wave Generation in Straits |
30 Sep 2011 |
8 pages |
| Authors:
Karl R Helfrich; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF PHYSICAL OCEANOGRAPHY
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| The long-term goal of this research is to improve scientists' understanding of the generation of nonlinear internal tides and waves by stratified flow over sills (e.g,. straits) and shelves and the subsequent evolution of the radiated internal disturbance, with particular emphasis on the role of rotation. The primary objectives will be to connect the generation process with the dynamics of the disintegration of the radiated internal tide into shorter, nonlinear ... |
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| Numerical Investigation of Nonlinear Internal Wave Generation and Breaking in Straits |
30 Sep 2011 |
9 pages |
| Authors:
Sonya Legg; PRINCETON UNIV NJ
|
| The long-term goal of this research is to develop a physical understanding of the processes that lead to mixing in the ocean with the aim of using this understanding to develop parameterizations of mixing suitable for global and regional models. Of particular focus are the mixing induced by tidal flow over topography and the mixing induced by breaking nonlinear internal waves. The primary scientific objective of this study is to ... |
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| Studying the Origin of the Kuroshio with an Array of ADCP-CTD Moorings |
30 Sep 2011 |
4 pages |
| Authors:
Ren-Chieh Lien; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
|
| Our long-term scientific goals are to understand the dynamics and identify the mechanisms of small-scale processes (i.e., internal tides, inertial waves, nonlinear internal waves (NLIWs), and turbulence mixing) in the ocean, and their interaction with mesoscale processes such as western boundary currents. We aim to develop improved parameterizations of mixing for ocean models. In this study, our focus is on the origin of the Kuroshio; the interaction among internal tides, ... |
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| Coastal Ocean Circulation Experiment off Senegal (COCES) |
30 Sep 2011 |
9 pages |
| Authors:
Pierre-Marie Poulain; ISTITUTO NAZIONALE DI OCEANOGRAFIA E DI GEOFISICA SPERIMENTALE SGONICO (ITALY)
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| The long term goals of this research project are 1) To investigate the dynamics of coastal areas dominated by buoyancy input and wind forcing, influenced by complex topography and interacting with the deep ocean. 2) To improve the understanding of coastal marine environmental evolution, with particular emphasis on eddy dynamics. During winter 2010, relatively cold and rich waters prevailed along the coasts of Mauritania and Senegal (12-22 deg N). These ... |
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| Optics, Acoustics and Stress in Situ (OASIS) |
30 Sep 2011 |
9 pages |
| Authors:
John H Trowbridge; Peter Traykovski; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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| To quantify and understand the effects of aggregation dynamics on the distribution of particles in the bottom boundary layer, and to understand how the properties of particles (composition, shape, and internal structure) affect their optical and acoustical properties. Obtain direct measurements of the turbulent Reynolds stress within the centimeters-thick wave boundary layer (WBL). Obtain concurrent velocity, turbulence and seafloor microtopography (bedforms) measurements to constrain the fluid dynamical environment within which ... |
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| Surface Wave Dynamics in the Coastal Zone |
30 Sep 2011 |
6 pages |
| Authors:
Gerbrant van Vledder; ALKYON HYDRAULIC CONSULTANCY AND RESEARCH BV EMMELOORD (NETHERLANDS)
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| The proposed work will contribute to the improvement of existing third-generation (3G) wave models as well as to the development of the next generation of numerical wave modeling capability. The results will be applicable in the coastal zone from deep water up to and including the surf zone. Our efforts will focus on analyzing high quality datasets to support further development of the source terms for triad interactions, depth-induced wave ... |
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| Subinertial Slope-Trapped Waves in the Northeastern Gulf of Mexico |
Jun-2009 |
12 pages |
| Authors:
Z R Hallock; W J Teague; E Jarosz; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Current velocity from moored arrays of acoustic Doppler current profilers (ADCPs) deployed on the outer shelf and slope, south of Mobile Bay in the northeastern Gulf of Mexico, shows evidence of alongslope, generally westward-propagating subinertial baroclinic Kelvin waves with periods of about 16 and 21 days, amplitudes of 5-10 cm/sec, and wavelengths of about 500 km. The observed waves were highly coherent over the slope between about 200 and 500 ... |
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| Acoustic Scattering from Sand Dollars (Dendraster excentricus): Modeling as High Aspect Ratio Oblate Objects and Comparison to Experiment |
Sep-2008 |
|
| Authors:
Gregory C Dietzen; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | Benthic shells can contribute greatly to the scattering variability of the ocean bottom, particularly at low grazing angles. Among the effects of shell aggregates are increased scattering strength and potential subcritical angle penetration of the seafloor. Sand dollars (Dendraster excentricus) occur commonly in the ocean and have been shown to be significant scatters of sound. In order to understand more fully the scattering mechanisms of these organisms, the scattering from ... |
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| Flow Through the Straits of the Philippine Archipelago Simulated by Global HYCOM and EAS NCOM |
Jan-2008 |
11 pages |
| Authors:
Harley E Hurlburt; E J Metzger; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| We plan to collaborate with other DRI participants to better evaluate and understand the dynamics seen in observations and model results within the Philippine Archipelago, a strategic region with numerous straits. Objectives for our DRI participation are (1) high resolution simulations (with and without tides; with and without data assimilation) which provide a larger scale context for the observations, (2) model data comparisons with the measurements, (3) studies of observational ... |
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| RCEX: Rip Current Experiment |
30 SEP 2007 |
6 pages |
| Authors:
Ad Reniers; ROSENSTIEL SCHOOL OF MARINE AND ATMOSPHERIC SCIENCE MIAMI FL DIV OF APPLIED MARINE PHYSICS
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| The long-term goals are to understand surf zone processes related to rip current systems through field observations. Rip currents occur commonly on most beaches and dominate many. In the past decade, it is recognized that beaches with straight and parallel contours are not a stable morphologic configuration whereas more complex beaches, which support the existence of rip current morphology, are stable and more common. The research objectives of the proposed ... |
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| RCEX: Rip Current Experiment |
30 SEP 2007 |
8 pages |
| Authors:
Timothy P. Stanton; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
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| Long term goals are to understand processes that cause the formation and maintenance of quasi-stationary rip channel / shoal systems in the surf zone. It is now recognized that this 3D configuration of the surf zone bathymetry is widespread and more representative than the simpler straight and parallel beaches that have been studied in recent years. A combination of detailed field observations and concurrent numerical modeling of the system are ... |
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| Water Masses in the Monterey Bay during the Summer of 2000 |
19 JAN 2007 |
21 pages |
| Authors:
Alex Warn-Varnas; Avijit Gangopadhyay; J. A. Hawkins; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| Water masses in Monterey Bay are determined from the CTD casts of the Monterey Ocean Observing System (MOOS) Upper-water-column Science Experiment (MUSE) August 2000 dataset. It is shown through cluster analysis that the MUSE 2000 CTD dataset contains 5 water masses. These five water masses are bay surface water (BSW), bay warm water (BWW), bay intermediate water (BIW), subarctic upper water (SUW), and North Pacific deep water (NPDW). The BWW ... |
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| Roughness Spectra and Acoustic Response from a Diver-Manipulated Sea Floor |
18 SEP 2006 |
7 pages |
| Authors:
Kevin B. Briggs; Michael D. Richardson; Kevin L. Williams; Anthony P. Lyons; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
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| A digital stereo photogrammetric system was designed and implemented to measure seafloor roughness in coastal sands. High-resolution images that achieve more than four pixels/millimeter in either the horizontal or vertical dimension are created by two cameras sealed in watertight housings and actuated simultaneously by a scuba diver. A Digital Elevation Model (DEM) of the photographed sea floor is created from digital autocorrelation of left and right paired images. The DEM ... |
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| Evidence of Multimodal Structure of the Baroclinic Tide in the Strait of Gibraltar |
08 SEP 2006 |
7 pages |
| Authors:
A. Vazquez; N. Stashchuk; V. Vlasenko; M. Bruno; A. Izquierdo; P. C. Gallacher; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| The multimodal structure of the baroclinic tides in the Strait of Gibraltar is studied using observations and numerical simulations. Observational data and model results revealed the presence of two types of tidal internal waves generated over Camarinal Sill (CS). One propagates toward the Mediterranean and disintegrates into a series of nonlinear short internal waves with amplitudes of 50 m and more. The second type, behind the first, propagates slower and ... |
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| Predicting the Distribution and Properties of Buried Submarine Topography on Continental Shelves |
30 Sep 2005 |
9 pages |
| Authors:
James P Syvitski; Scott Peckham; COLORADO UNIV AT BOULDER INST OF ARCTIC AND ALPINE RESEARCH
|
| Long-term goals are to compile geological data and develop methods to predict the distribution and properties of features hypothesized to be responsible for sonar geoclutter. Geological structures just beneath the seafloor, such as steep-walled channels, may have high-angle reflecting surfaces that can return false sonar alarms to ships operating in the littoral zone. The major goal is to contribute to the reduction or mitigation of geologic clutter observed on fleet ... |
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| Predicting the Distribution and Properties of Buried Submarine Topography on Continental Shelves |
30 Sep 2005 |
5 pages |
| Authors:
Patricia Wiberg; Alan Howard; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF ENVIRONMENTAL SCIENCES
|
| The long-term goal of the Geoclutter modeling project is to predict the distribution and properties of buried channels that may be responsible for geoclutter on continental margins of interest. The overall objectives of our project are 1) to determine the characteristics of channel features that can form when the present continental shelf is subject to sea-level variations and 2) to determine whether these features would be buried when sea-level returned ... |
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| Seafloor Roughness, Sediment Grain Size, and Temporal Stability |
JUL 2005 |
9 pages |
| Authors:
Kevin B. Briggs; Anthony P. Lyons; Eric Pouliquen; Larry A. Mayer; Michael D. Richardson; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
|
| Measurement of seafloor microtopography is rapidly approaching the status of a standardized element of geoacoustic characterization of the sea floor. With the advent of underwater stereo cameras and, recently, multiple-megapixel digital cameras adapted for underwater use, more investigators are measuring seafloor roughness at high resolution for applications to high-frequency acoustic modeling. An assessment of the methodologies used to characterize seafloor roughness, the parameterizations of the characterization of seafloor roughness, and ... |
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| The Thermohaline Circulation in Semi-Enclosed Marginal Seas |
2005 |
|
| Authors:
Michael A. Spall; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The principles governing the buoyancy-forced circulation within marginal seas, and their exchange with the open ocean, are addressed using a series of idealized numerical models and theory. It is found that small scale mixing of density and momentum near the boundaries plays a central role in the net down-welling within the marginal sea and, at times, in the basin-scale stratification. Bottom topography is also found to be very important for ... |
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| The Use of Hydroacoustic Phases for the Detection of Oceanic Events: Observations and Numerical Modeling |
JUL 2004 |
63 pages |
| Authors:
Catherine DE Groot-Hedlin; Donna Blackman; John Orcutt; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
|
| Hydroacoustic monitoring of the Comprehensive Nuclear Test Ban Treaty (CTBT) requires the ability to detect and locate phenomena that give rise to acoustic signals. An improved understanding of the coupling of seismic energy to acoustic energy is necessary to improve location estimates of earthquakes and volcanic eruptions. Using known variations in near-source bathymetry, the authors demonstrated that scattering of seismic to acoustic energy at a rough seafloor yields the approximate ... |
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| Proceedings, ONR Shallow Water Acoustics 2006 Workshop Applied Physics Laboratory, University of Washington 25-26 September 2003 |
APR 2004 |
20 pages |
| Authors:
Dajun Tang; Nick Makris; James Lynch; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
|
| The Ocean Acoustics Code, Office of Naval Research, sponsored a two- day workshop on shallow water acoustics. The primary purpose of the workshop was to define and identify key basic research problems to be addressed in a field experiment to be conducted in fiscal year 2006. Seventeen scientists attended the workshop. Several researchers contributed poster presentations as well. The report consists of an 18-page workshop summary, 18 PowerPoint presentations, and ... |
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| Mine Burial Experiments at the Martha's Vineyard Coastal Observatory |
03 FEB 2004 |
8 pages |
| Authors:
Peter Traykovski; Michael D. Richardson; John A. Goff; Larry Mayer; Roy Wilkens; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Several experiments to measure the burial of seafloor mines by scour and fill have been conducted at the Woods Hole Oceanographic Institution Martha's Vineyard Coastal Observatory (MVCO). Two sets of mine scour burial experiments were conducted during the winters of 2001-2002 and 2002-2003 with a single optically instrumented mine in the field of view of a rotary sidescan sonar. Sixteen mines were deployed from October 2003 to April of 2004, ... |
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| NPS ARIES Forward Look Sonar Integration |
01-Jan-2004 |
6 pages |
| Authors:
A J Healey; D P Horner; NAVAL POSTGRADUATE SCHOOL MONTEREY CA CENTER FOR AUTONOMOUS UNDERWATER VEHICLE RESEARCH
|
| This work integrated an experimental Blazed Array Forward Looking Sonar (FLS) developed by the University of Washington, Applied Physics Laboratories into the ARIES autonomous underwater vehicle (AUV). Experiments were conducted and data were gathered using this sonar in a variety of environments. The images generated were analyzed to provide information for use in the further development of forward look obstacle detection and avoidance technologies. The year-end goal of the project ... |
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| A Terrain-Following Crystal Grid Finite Volume Ocean Circulation Model |
2004 |
26 pages |
| Authors:
Peter C. Chu; Chenwu Fan; NAVAL POSTGRADUATE SCHOOL MONTEREY CA NAVAL OCEAN ANALYSIS AND PREDICTION LAB
|
| A three-dimensional hydrostatic finite volume ocean model is developed solving the integral dynamical equations. Since the basic (integral) equations are solved for finite volumes rather than grid points, the flux conservation is easily enforced even on arbitrary meshes. Both upwind and high-order combine compact schemes can be incorporated into the model to increase computational stability and accuracy. For abrupt topography, a terrain-following grid discretization is designed to reduce computational errors ... |
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| The Shelf-Edge Environment in the Central East China Sea and Its Impact on Low Frequency Acoustic Propagation |
OCT 2002 |
29 pages |
| Authors:
Steven R. Ramp; Ching-Sang Chiu; Fred Bahr; James Lynch; Tim Duda; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
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| Viewgraphs on presentation of the shelf-edge environment in the Central East China Sea and its impact on low frequency acoustic wave propagation. |
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| Development and Verification of a Comprehensive Community Model for Physical Processes in the Nearshore Ocean |
2002 |
11 pages |
| Authors:
James T. Kirby; John S. Allen; Thomas G. Drake; Steve Elgar; Robert T. Guza; Daniel M. Hanes; Thomas H. Herbers; James M. Kaihatu; George Mellor; H. T. Ozkan-Haller; DELAWARE UNIV NEWARK CENTER FOR APPLIED COASTAL RESEARCH
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| Our goal is to develop a comprehensive, verified community model that predicts nearshore hydrodynamics, sediment transport, and seabed morphology changes given offshore wave conditions and initial bathymetry. The basic scientific objective is to synthesize understanding of physical processes in the nearshore ocean by developing a model for waves and resulting radiation stresses and mass fluxes over evolving coastal bathymetry and currents wave-induced circulation sediment transport and morphological evolution. An additional ... |
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| Evidence from Gravity Anomalies for Interactions of the Marion and Bouvet Hotspots with the Southwest Indian Ridge: Effects of Transform Offsets |
MAR 2001 |
|
| Authors:
Jennifer E. Georgen; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The ultra-slow spreading Southwest Indian Ridge (SWIR) presents a unique environment to study the interactions between hotspots and ridges with highly segmented geometry. Using recently available satellite free-air gravity and shipboard bathymetry data, we obtain mantle Bouguer (MBA) and residual mantle Bouguer anomalies (RMBA) by removing from free-air gravity the attractions of seafloor topography, sediment thickness variations, a reference crust, and theoretically-predicted effects of lithospheric cooling. The Bouvet hotspot, previously ... |
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| A Fine Resolution Model of the Coastal Eastern Boundary Current Systems off Iberia and Morocco |
MAR 2001 |
109 pages |
| Authors:
Antonio S. Martinho; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| To investigate the role of wind forcing, bottom topography and thermohaline gradients on classical as well as unique features in the northern Canary Current system (NCCS), four experiments are conducted with a sigma coordinate primitive equation model. The first experiment, which investigates the pressure gradient force error, shows that velocity errors inherent in three dimensional sigma coordinate models can be successfully reduced from ^1 m/s to less than 0.5 cm/s ... |
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| Circulation in the Vicinity of Descending Overflows |
22 JAN 2001 |
|
| Authors:
Michael A. Spall; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| Analytic and numerical models have been used to study the large-scale circulation and exchange between marginal seas and the open ocean resulting from diapycnal mixing near lateral boundaries. The results indicate that mixing near topography can force strong circulations far from the region of mixing, sometimes extending into an adjacent ocean basin. The exchange between marginal seas and the open ocean will be strongly dependent on whether the marginal sea ... |
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| East Asian Marginal Seas Prediction Using a Coastal Atmosphere-Ocean Coupled System (CAOCS) |
2001 |
4 pages |
| Authors:
Peter C. Chu; Shihua Lu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The South China Sea (SCS), Yellow/East China Sea (YES), and Japan/East Sea (JES) are major East Asian marginal seas (EAMS). The complex topography includes the broad shallows of the Sunda Shelf in the south/southwest of SCS; the continental shelf of the Asian landmass in the north, extending from the Gulf of Tonkin to the YES; deep, elliptical shaped SCS and JES basins, and numerous reef islands and underwater plateaus scattered ... |
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| Global Ocean Modeling and State Estimation in Support of Climate Research |
OCT 1999 |
24 pages |
| Authors:
D. Stammer; R. Bleck; C. Boning; P. Demey; H. Hurlburt; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| During the last decade it has become obvious that the ocean circulation shows vigorous variability on a wide range of time and space scales and that the concept of a "sluggish" and slowly varying circulation is rather elusive. Increasing emphasis has to be put, therefore, on observing the rapidly changing ocean state on time scales ranging from weeks to decades and beyond, and on understanding ... |
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| Dynamical Mechanisms for the South China Sea Seasonal Circulation and Thermohaline Variabilities |
APR 1999 |
22 pages |
| Authors:
Peter C. Chu; Nathan L. Edmons; Chenwu Fan; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The seasonal ocean circulation and the seasonal thermal structure in the South China Sea (SCS) were studied numerically using the Princeton Ocean Model (POM) with 20-km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography. A 16-month control run was performed using climatological monthly mean wind stresses, restoring-type surface salt and heat, and observational oceanic inflow/outflow at the open boundaries. The seasonally averaged effects of isolated forcing ... |
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| Adriatic Sea Surface Temperature: Satellite and Drifter Observations, May to October, 1995 |
MAR 1999 |
102 pages |
| Authors:
Jason A. Vogt; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The Adriatic Sea is the northernmost semi-enclosed basin of the Mediterranean Sea and has been the subject of various oceanographic studies since the 19th century. Substantial changes in water properties (such as temperature) and in circulation, both spatially and temporally (seasonal) occur as a result of extreme forcings by the local winds and by the fresh water discharge by rivers. In recent years, extensive measurements have been made, primarily through ... |
|
| IOC/IASC/IHO Editorial Board for the International Bathymetric Chart of the Arctic Ocean Report of Meeting: Copenhagen, Denmark; October 19-20 1998 |
JAN 1999 |
50 pages |
| Authors:
Ron Macnab; Arne Nielsen; GEOLOGICAL SURVEY OF CANADA DARTMOUTH (NOVA SCOTIA)
|
| Compilation of abstracts and report from the conference/meeting entitled "IOC/IASC/IHO Editorial Board for the International Bathymetric Chart of the Arctic Ocean" held in Copenhagen, Denmark, 19 - 20 October 1998. |
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| Side Scan Sonar Survey of Clinch River and Poplar Creek, Tennessee |
JAN 1999 |
85 pages |
| Authors:
Keith J. Sjostrom; Rodney L. Leist; Thomas S. Harmon Jr.; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| During the 1950s, quantities of chemical materials were released into local waterways in association with nuclear energy research and weapons components production at the Oak Ridge National Laboratory (ORNL). Plans and specifications for studying the distribution and extent of any contamination are presently being prepared by ORNL. The objective of this study is to delineate the characteristics and features of the river bottom topography and sediments along Clinch River and ... |
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| Scattering of High-Frequency Acoustic Energy from Discrete Scatterers on the Seafloor: Glass Spheres and Shells |
1999 |
7 pages |
| Authors:
Michael E. Richardson; Kevin B. Briggs; Kevin L. Williams; Darrell R. Jackson; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Shells and shell debris are common at the water/seafloor interface. Quantifying the scattering from shells is thus important for predicting high frequency backscattering from the seafloor. A backscattering experiment is described in which glass beads (radius equal to 1.75 cm) and shells (largest dimension tip to about 10 cm) were placed near a bottom-mounted sonar and backscattering examined as a function of the number of discrete scatterers Supported by Office ... |
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| Effects of Changing Roughness on Acoustic Scattering: (2) Anthropogenic Changes |
1999 |
9 pages |
| Authors:
Michael E. Richardson; Kevin B. Briggs; Anthony Lyons; Kevin Williams; Darrell Jackson; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Deliberate modification of bottom roughness including smoothing to eliminate centimeter scale natural roughness and raking to induce quasiperiodic roughness was investigated using diver observation, quantification of bottom roughness from Stereo photography, and measurement of acoustic backscattering strength. At 40 kHz. raking perpendicular to the acoustic line-of-sight with a tine spacing equal to one-half wavelength increased scattering by 12-18 dB which decayed to background levels within 24 hours due to biological ... |
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| SeaSoar CTD Observations During the Coastal Mixing and Optics Experiment: R/V Endeavor Cruises from 14 August to 1 September 1996 and 25 April to 15 May 1997 |
OCT 1998 |
502 pages |
| Authors:
R. O'Malley; J. A. Barth; A. Erofeev; J. Fleischbein; P. M. Kosro; OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES
|
| Two physical oceanography cruises on the R/V Endeavor were conducted by the co-PIs Jack Barth and Mike Kosro as part of the ONR-sponsored Coastal Mixing and Optics (CMO) Accelerated Research Initiative. The objective was to rapidly survey a region around 40.5N, 70.5W where a set of moorings and a stationary vessel conducting profiling operations were located. The first cruise took place during a period of strong summer stratification (14 August ... |
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| Evolution of the Continental Slope: Mechanics of Debris Flows and Landscape Evolution Modeling |
30 SEP 1998 |
4 pages |
| Authors:
Gary Parker; MINNESOTA UNIV MINNEAPOLIS ST ANTHONY FALLS HYDRAULIC LAB
|
| My long-term goals are to a) develop a mechanistic understanding of submarine debris flows and associated turbidity currents and b) incorporate this understanding into the broader context of the evolution of the morphology of the continental slope. Objectives can be enumerated as follows: 1) Determine the mechanisms of submarine debris flow runout. 2) Characterize the deposits of submarine debris flows. 3) Characterize and describe tendencies for transition to turbidity currents. ... |
|
| A P-Vector Approach to Absolute Geostrophic Currents in the Adriatic Sea |
MAR 1998 |
89 pages |
| Authors:
Renato L. Pinto; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| With the recent conflict in Bosnia-Herzegovina being in the world news front, the Adriatic Sea has become an important strategic operating area for the North Atlantic Treaty Organization (NATO) and for the U.S. Navy. The NATO Undersea Research Centre located in La Spezia, Italy carried out the Otranto Gap (OGAP) project in 1994 and 1995 to assess the oceanography and bottom geology of the Southern Adriatic. As part of this ... |
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| Structure and Dynamics of the Pacific Upper Mantle |
FEB 1998 |
|
| Authors:
Rafael Katzman; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| A new tomographic technique is employed to investigate the structure and dynamics of the Pacific upper mantle. We invert frequency-dependent travel times residuals of three-component turning and surface waves such as S, SS, SSS, R1 and G1 together with band-center travel times of ScS reverberations for the 2D composite structure in the plane of two Pacific corridors. The model parameters include shear-speed variations throughout the mantle, perturbations to radial shear-wave ... |
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| Pressure/Temperature Logger (PTL) Development and Field Deployment for the Great Bay, NH, Tidal Dynamics Experiment |
JAN 1998 |
|
| Authors:
Carl T. Friedrichs; Wayne D. Spencer; David G. Aubrey; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| During 1992 and 1993 experiments were conducted in the shallow east side of Great Bay, New Hampshire. These experiments were conducted to better understand the morphodynamics and evolutionary tendencies of shallow tidal embayments and intertidal flats. Hardware and software used in the collection of data are described. Discussed also are techniques used to collect data. Six pressure temperature loggers (PTL) and one current meter (TCSWG) were ... |
|
| HF Broadband Time/Frequency Spreading |
Jan 1998 |
5 pages |
| Authors:
Richard L Culver; APPLIED RESEARCH LABORATORY STATE COLLEGE PA
|
| The long-term goal is to provide underwater weapon system designers with a means of testing broadband signals and signal processing algorithms in shallow ocean scenarios where time and frequency (T/F) spread are often significant. This capability is required for sonar signal processing optimization and wideband signal and processor design. The scientific objectives are to measure T/F spread directly along with relevant environmental parameters (primarily wind speed, sound speed profile, and ... |
|
| Modeling the Response of Monterey Bay to Observed and Model Winds and Tidal Forcing |
Jan 1998 |
7 pages |
| Authors:
Le N Ly; Jeffrey D Paduan; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The long-term goals of our project are to improve comprehensive high-resolution numerical models of the coastal ocean circulation for regions with complex bottom topography, coastlines, and multi-scale physical phenomena using enhanced gridding technology, nested open boundary conditions, and ultimately, data assimilation of new observational data types such as surface currents from the Coastal Applications Radar (CODAR). The goals include model validations against observed data. This program seeks to apply new ... |
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| An EM Survey of the New Jersey Continental Shelf |
Jan 1998 |
5 pages |
| Authors:
Rob L Evans; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
|
| Maps of sedimentary physical properties are essential to a complete understanding of processes shaping the continental shelf. We have demonstrated that measurements of electrical resistivity can provide exciting new insights into shelf structure, and aim to make electromagnetic (EM) surveys a routine component of seafloor classification programs. The first objective of this research is to image, in terms of electrical properties, buried paleo-channels within two regions surveyed in 3D by ... |
|
| CoBOP Coral Reefs: Optical Closure of a Coral Reef Submarine Light Field |
Jan 1998 |
5 pages |
| Authors:
Charles S Yentsch; David A Phinney; BIGELOW LAB FOR OCEAN SCIENCES WEST BOOTHBAY HARBOR ME
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| The primary goal for this project is to obtain optical closure of the submarine light field overlying coral reef environments by measuring the basic optical properties of the water column and benthic surfaces. These measurements can also be used to develop remote sensing algorithms for the determination of biomass, diversity and primary production of benthic corals, seagrasses and macroalgal communities. Our objectives are to investigate the time scales of variability ... |
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| Boundary Stress Over Rough Topography |
Jan 1998 |
5 pages |
| Authors:
Parker MacCready; WASHINGTON UNIV SEATTLE SCHOOL OF OCEANOGRAPHY
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| Our long-term goal is to understand the how bottom topography affects oceanic circulation and mixing. This is particularly important in coastal regions, where current interactions with rough slopes can force turbulent mixing and strong eddy and wave activity. In this project I focus on the following question: What scales of bottom roughness are most effective for the creation of bottom form stress? By bottom roughness I mean chiefly the little-explored ... |
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| Airborne Measurement of the Space/Time Properties of Waves in the Coastal Zone |
Jan 1998 |
3 pages |
| Authors:
William J Plant; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| Our long-term goal in this project is to utilize a newly developed airborne microwave technique to monitor the propagation of waves from the deep ocean into the coastal zone. Our scientific objectives are to investigate the generation of forced waves produced by quadratic nonlinearities, the refraction of swell in shallow water, the possibility of determining bottom topography from refraction, and the effects of bottom topography and composition on the reflection ... |
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| High Frequency Bottom Interaction Acoustics in the Atlantic Natural Laboratory |
Jan 1998 |
5 pages |
| Authors:
Ralph A Stephen; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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| The long term objectives of this project are as follows: (1) to develop a numerical technique capable of predicting the low frequency acoustic wave field scattered from geologically realistic models of the bottom/sub-bottom environment; (2) to isolate from the scattering models the physical mechanisms that dominate the long-range reverberation from the seafloor; and (3) to characterize the variations in bottom topography and sub-bottom properties that control the scattering of low ... |
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Reports by Keyword(s)
OCEAN BOTTOM TOPOGRAPHY
