| Pan-Arctic Distributions of Continental Runoff in the Arctic Ocean |
11 Jan 2013 |
7 pages |
| Authors:
Cedric G Fichot; Karl Kaiser; Stanford B Hooker; Rainer M Amon; Marcel Babin; Simon Belanger; Sally A Walker; Ronald Benner; SOUTH CAROLINA UNIV COLUMBIA
|
 | Continental runoff is a major source of freshwater, nutrients and terrigenous material to the Arctic Ocean. As such, it influences water column stratification, light attenuation, surface heating, gas exchange, biological productivity and carbon sequestration. Increasing river discharge and thawing permafrost suggest that the impacts of continental runoff on these processes are changing. Here, a new optical proxy was developed and implemented with remote sensing to determine the first pan-Arctic distribution ... |
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| Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility. ESTCP Cost and Performance Report |
Aug 2012 |
64 pages |
| Authors:
ENVIRONMENTAL SECURITY TECHNOLOGY CERTIFICATION PROGRAM OFFICE (DOD) ARLINGTON VA
|
| The goal of the project was to develop and standardize a procedure using field deployable solid phase microextraction (SPME) for the measurement of freely dissolved porewater concentrations of hydrophobic organics and demonstrate the relationship of these measurements to contaminant flux, bioavailability, and bioaccumulation. In situ SPME is a passive sampling approach for measuring hydrophobic organic contaminants in porewater and involves the insertion of a polymer sorbent into the sediments for ... |
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| Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility (User's Manual) |
May 2012 |
18 pages |
| Authors:
Danny Reible; Gui Lotufo; TEXAS UNIV AT AUSTIN DEPT OF CIVIL ENGINEERING
|
| This method is an operating procedure for in-situ measurement of sediment pore water concentrations with solid phase microextraction using polydimethyl siloxane as the extractant. The method is used to assess the mobile and available contaminants in the pore water. Included in this description are procedures for preparation, deployment, retrieval, processing and interpretation of the collected pore water concentrations. The method is applicable to hydrophobic organic contaminants (HOCs) and the focus ... |
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| Alternative Penetrometers to Measure the Near Surface Strength of Soft Seafloor Soils |
30 Sep 2011 |
7 pages |
| Authors:
Mark R Tufenkjian; CALIFORNIA UNIV LOS ANGELES DEPT OF CIVIL ENGINEERING
|
| Develop an alternative penetrometer to accurately measure the undrained shear strength of near surface soft seafloor soils. Further the education of participating undergraduate students by active involvement in research and mentoring activities. In collaboration with the Naval Facilities Engineering Service Center (NFESC) in Port Hueneme, assess the feasibility of using full-flow penetrometer technology to meet Navy requirements. Design, build, and test a full-flow penetrometer that will accurately measure the near ... |
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| Tidal Flats, Muddy Seafloors, Sandy Coasts, and Inlets |
30 Sep 2011 |
11 pages |
| Authors:
Britt Raubenheimer; Steve Elgar; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The long-term goal is to develop field-verified models for the evolution of surface-gravity waves, circulation, sediment transport, and the subsequent morphological response in shallow, coastal waters. The objectives of our studies in FY11 were to analyze observations of currents, waves, and bathymetry on tidal flats, and to develop, test, and improve models for tidal-flat processes. Specific goals related to tidal flats were to investigate the relative importance of riverine and ... |
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| Beaufort Sea Methane Hydrate Exploration: Energy and Climate Change |
27 May 2011 |
34 pages |
| Authors:
Richard B Coffin; L J Hamdan; J P Smith; R Plummer; L Millholland; R Larson; W Wood; NAVAL RESEARCH LAB WASHINGTON DC
|
| This is a geochemical report for the MITAS 1 expedition on the Beaufort Sea during September 2009, aboard the USCG Polar Sea. The overall cruise focus integrated research expertise in coastal ocean geophysics, sediment geochemistry, dissolved and free methane fluxes through the water column and into the atmosphere, sediment and water column microbiology and biogeochemistry, and detailed characterization of the sub-seafloor geology to address the following research topics: (1) Acquire ... |
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| Alternative Penetrometers to Measure the Near Surface Strength of Soft Seafloor Soils |
2011 |
9 pages |
| Authors:
Mark R. Tufenkjian; CALIFORNIA STATE UNIV LOS ANGELES DEPT OF CIVIL ENGINEERING
|
| Long-term goals: Develop an alternative penetrometer to accurately measure the undrained shear strength of near surface soft seafloor soils. Further the education of participating undergraduate students by active involvement in research and mentoring activities. Objectives: In collaboration with the Naval Facilities Engineering Service Center (NFESC) in Port Hueneme, assess the feasibility of using full-flow penetrometer technology to meet Navy requirements. Design, build, and test a full-flow penetrometer that will accurately ... |
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| Alternative Penetrometers to Measure the Near Surface Strength of Soft Seafloor Soils |
2010 |
9 pages |
| Authors:
Mark R. Tufenkjian; CALIFORNIA STATE UNIV LOS ANGELES DEPT OF CIVIL ENGINEERING
|
| Develop an alternative penetrometer to accurately measure the undrained shear strength of near surface soft seafloor soils. Further the education of participating undergraduate students by active involvement in research and mentoring activities. In collaboration with the Naval Facilities Engineering Service Center (NFESC) in Port Hueneme, assess the feasibility of using full-flow penetrometer technology to meet Navy requirements. Design, build, and test a full-flow penetrometer that will accurately measure the near ... |
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| Potential Transport Pathways of Terrigenous Material in the Gulf of Papua |
25 FEB 2006 |
5 pages |
| Authors:
Timothy Keen; Dong S. Ko; R. L. Slingerland; Shelly Riedlinger; Peter Flynn; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| This work discusses potential transport pathways of terrigenous material in the Gulf of Papua (GoP), New Guinea, using Lagrangian tracers as proxies for clay minerals and finer particles. The tracers are transported by currents from the East Asia Seas implementation of the Navy Coastal Ocean Model. The results suggest that clay minerals input from rivers along the northwest coast of the GoP accumulate on the inner shelf with high concentrations ... |
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| Microbial Fuel Cells and Sensors |
01 JUN 2005 |
4 pages |
| Authors:
J. G. Zeikus; MICHIGAN STATE UNIV EAST LANSING DEPT OF BIOCHEMISTRY
|
| This final report presents information on a new generation of graphite electrodes containing iron or manganese that were developed for use in microbial fuel cells and sensor devices. These electrodes were employed to sense chemicals and to produce electricity from sewage sludge and marine sediments. |
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| Environmental Mitigation Ranges around Australia |
FEB 2004 |
|
| Authors:
Paul Clarke; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA) MARITIME OPERATIONS DIV
|
 | URS Australia is currently writing "Environmental Management Plan for Australian Maritime Exercise Areas" for the ADF. To help URS, the MOD within DSTO has modeled the expected received sound pressure levels for a number of different environments and sonar frequencies around Australia. The maximum ranges the sound pressure levels dropped below 182 and 160 dB were then calculated for a number of different sonars operating at levels indicative of or ... |
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| Subduction Dynamics at the Middle America Trench: New Constraints from Swath Bathymetry, Multichannel Seismic Data, and (10)Be |
SEP 2003 |
|
| Authors:
Robyn K. Kelly; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| The cosmogenic radionuclide (10)Be is a unique tracer of shallow sediment subduction in volcanic arcs. The range in (10)Be enrichment in the Central American Volcanic Arc between Guatemala and Costa Rica is not controlled by variations in (10)Be concentrations in subducting sediment seaward of the Middle America Trench. Grain size is the principal control on the sedimentary (10)Be concentrations. (10)Be in fine-grained, terrigenous sediments is diluted by larger grained volcanogenic ... |
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| Sediment Acoustics |
01 DEC 2001 |
7 pages |
| Authors:
R. D. Stoll; LAMONT-DOHERTY EARTH OBSERVATORY PALISADES NY
|
| This grant has funded work aimed primarily at developing a mathematical model to describe geoacoustic and seismic wave propagation in ocean sediments based on the knowledge of certain primitive variables such as porosity and grain-size distribution. The model is based on the classical Biot theory extended to take into account various mechanisms of energy loss that are known to be important in marine sediments. After the initial development of the ... |
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| Backscattering from Bioturbated Sediments at Very High Frequency |
DEC 2001 |
|
| Authors:
E. Pouliquen; A. P. Lyons; N. G. Pace; E. Michelozzi; L. Muzi; SACLANT UNDERSEA RESEARCH CENTRE LA SPEZIA (ITALY)
|
| The environment significantly affects mine hunting system performance. This is especially true in mine hunting conditions to detect low- contrast mines in cluttered environments. Inexact performance predictions result in poor evaluations of mine clearance which, in turn, lead to inaccurate assessments of remaining risk to follow-on forces in the channel or area. This report provides a quantification and understanding of environmental phenomena critical to acoustic backscattering at mine hunting frequency. ... |
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| Object Detection in Oceanic Sediments Using Quadratic Detectors and Wavelets |
OCT 2000 |
16 pages |
| Authors:
Eric Flattem; Maria Kalcic; Andrew Martinez; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Methods for processing parametric broadband sonar returns are presented with the goal of locating buried objects from clutter. A gain correction algorithm based on wavelets is employed to correct for frequency dependent signal losses in multiple frequency bands. Quadratic detectors are designed to filter in time, frequency, and spatial domains simultaneously. These normalized quadratic detectors are shown to successfully isolate regions with similar characteristics by exploiting spectral and temporal features ... |
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| Biot-Based Geoacoustic Investigation of Lake Arkabutla, Mississippi |
AUG 2000 |
116 pages |
| Authors:
Richard G. McGee; Robert F. Ballard Jr.; Rodney L. Leist; EVANS-HAMILTON INC SEATTLE WA
|
| The need exists for development of in situ techniques for more accurately determining site conditions off shore of dams and levees in lakes and reservoirs within hazard areas. This report describes the use of a new data processing approach utilizing a Biot theory approach to assess acoustic sediment interactions in porous, saturated media. Ramifications of the Biot theory may aid engineering in accurately assessing liquefaction potential of ... |
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| Buried Mine Detection and Classification (Research Summary 1996-1999) |
JUL 1999 |
|
| Authors:
A. Maguer; W. L. Fox; B. Zerr; A. Tesei; E. Bovio; SACLANT UNDERSEA RESEARCH CENTRE LA SPEZIA (ITALY)
|
| The applicability of low-frequency sonar (2-16 kHz) to buried mine detection has been investigated. Experiments were performed on sound penetration into sediment, buried target detection and broadband multiple aspect classification. The results of the experiments are given in this report and compared with modelled results. One of the main results is our success in understanding the physical mechanisms contributing to subcritical penetration into sediment. It ... |
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| Coastal Ocean Processes Symposium: A Tribute to William D. Grant |
MAY 1999 |
|
| Authors:
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| This report is a compilation of abstracts distributed at the Coastal Ocean Processes Symposium: A Tribute to William D. Grant at the Woods Hole Oceanographic Institution from September 27-September 30, 1998. |
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| Experimental and Theoretical Studies of Near-Bottom Sediments to Determine Geoacoustic and Geotechnical Properties |
14 DEC 1998 |
5 pages |
| Authors:
R. D. Stoll; R. Flood; E. O. Bautista; LAMONT-DOHERTY EARTH OBSERVATORY PALISADES NY
|
| In a program designed to develop methods for predicting and measuring certain geoacoustic and geotechnical properties of the sediments immediately beneath the sea floor, several new tools were developed to measure in situ properties such as undrained shear strength, shear wave velocity and angle of internal friction. These tools include a motorized penetrometer designed to measure quasi static cone penetration resistance up to depths of two meters into the bottom, ... |
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| Investigations of Sediment Dynamics in STRATAFORM |
30 SEP 1998 |
|
| Authors:
David G. Aubrey; David A. Cacchione; WOODS HOLE GROUP INC FALMOUTH MA
|
| The overall long-term goal of STRATAFORM is to advance our understanding of the development of stratigraphic sequences on continental shelves and slopes. An essential part of this understanding comes from direct measurements of the response of bottom and suspended sediment to oceanic forcing in the study areas. In this project our specific long-term goal is to understand the variability of the sediment response at the seafloor to bottom currents and ... |
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| Hydrodynamic Dampening System for the Precise Measurement of Dynamic Sediment Pore Water Pressure |
08 SEP 1998 |
|
| Authors:
Richard H. Bennett; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A multi-sensor piezometer is disclosed that includes a shaft and an upper chamber. The shaft houses a plurality of porous stones that operatively cooperate with the positive input of respective differential pressure transducers. The multi-sensor piezometer further includes a hydraulic dampening system which eliminates the effect of high frequency surface waves on the precision of the multi-sensor piezometer to measure pore pressures in marine sediments. |
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| Broadband Mine Detection and Classification in Shallow Water |
Jan 1998 |
5 pages |
| Authors:
Peter Kaczkowski; David Moore; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
|
| Our long-term goal is to advance the development of underwater mine reconnaissance sonar for shallow water environments. Specifically, we wish to increase the range at which classification of mine-like returns can be done successfully (low probability of false alarms) and thus increase the reconnaissance area coverage rate. We also wish to improve the detection of buried mines in sandy bottom environments, and to explore the potential of low frequency and ... |
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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 ... |
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| Further Investigation of the Eel River Shelf Resistivity Structure |
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. But there is more work to be done in tying the results of electromagnetic (EM) studies to those of more conventional surveys such as the extensive coring efforts on the Eel River shelf, high-resolution seismic reflection profiling, ... |
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| Spectral Wave Decay Due to Bottom Friction on the Inner Shelf |
Jan 1998 |
7 pages |
| Authors:
Timothy P Stanton; Edward B Thornton; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The long-term goals of this research are to observe and model wave and boundary layer processes to determine wave dissipation in the coastal and nearshore ocean using novel instrumentation techniques. The primary scientific objective of this project is to measure the bottom dissipation of surface gravity waves as they shoal across the continental shelf. Detailed observations of the bottom boundary layer, resolving the thin oscillatory boundary layer, will be made ... |
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| Offset-Vertical Seismic Profiling for Marine Gas Hydrate Exploration -- Is it a Suitable Technique? First Results from ODP Leg 164 |
JUL 1997 |
10 pages |
| Authors:
L. A. Pecher; W. S. Holbrook; R. A. Stephen; H. Hoskins; D. Lizarralde; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS GEOLOGY/ GEOPHYSICS SECTION
|
| Walkaway vertical seismic profiles were acquired during Ocean Drilling Project (ODP) Leg 164 at the Blake Ridge to investigate seismic properties of hydrate-bearing sediments and the zone of free gas beneath them. An evaluation of compressional (P-) wave arrivals Site 994 indicates P-wave anisotropy in the sediment column. We identified several shear (S-) wave arrivals in the horizontal components of the geophone array in the borehole and in data recorded ... |
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| Continuously Logged Sediment Acoustical and Physical Properties Data, R/ V Haakon Mosby Cores, Norwegian/Greenland Sea |
18 APR 97 |
166 pages |
| Authors:
William B. Sawyer; Frederick A. Bowles; Lisa Phelps; Peter R. Vogt; Kathleen Crane; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS GEOLOGY/ GEOPHYSICS SECTION
|
| Sediment cores were collected in the Greenland/Norwegian Sea for the purpose of ground-truthing previously collected sidescan imagery. This report presents the results of shore-based analyses performed on the cores. Interpretive results are not included. The unopened cores were continuously logged at 2-cm intervals for compressional-wave velocity and gamma-ray attenuation. Wet bulk density, porosity, water content, and void ratio were calculated from the attenuation measurements. Analytical results are presented in the ... |
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| Geostatistical and Neural-Net Seafloor Classification at High Resolution and Related Scaling Properties |
21 MAR 97 |
13 pages |
| Authors:
Ute C. Herzfeld; COLORADO UNIV AT BOULDER INST OF ARCTIC AND ALPINE RESEARCH
|
| The objective of my research under this grant is the development of an intelligent system for the automated classification of the seafloor using acoustic data. The work is a contribution to the Acoustical Reverberation Special Research Program (ARSRP). We have developed a method for surface classification, incorporating ideas from the theory of geostatistics (in short, the method has been called Geostatistical classification method). Under this project, we have finalized parameter ... |
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| Environmental Ocean-Bottom Backscattering Strength Based on the Mourad- Jackson Model |
15 FEB 97 |
18 pages |
| Authors:
Ralph N. Baer; David M. Fromm; NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS SYSTEMS BRANCH
|
| Current formulations used by the Navy to model reverberation in active-acoustic-system performance scenarios are heuristic in that they do not include physical descriptors of the environment. Here we investigate a model developed originally by Pierre Mourad and Darrell Jackson of APL/UW for the backscatter component of reverberation that includes environmental descriptors in the form of eight environmental parameters, most of which can be experimentally determined in a given scenario. This ... |
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| Geoacoustic Study of New Jersey Coast from Townsends Inlet to Hereford Inlet |
JUL 96 |
244 pages |
| Authors:
Richard G. McGee; Darla C. McVan; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS HYDRAULICS LAB
|
| A comprehensive geoacoustic study has been performed for a 7-mile stretch of coastline off the coast of New Jersey between Townsends Inlet and Hereford Inlet for the purpose of defining the limits of available granular materials. The work was performed in support of the U.S. Army Engineer District, Philadelphia's, feasibility study for shore protection solutions for the Atlantic coast of New Jersey. Specifically, the objective of this investigation was to ... |
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| Sediment Characterization and Beachfill Borrow Area Assessment of the Delaware Bay Study. Report 1. Identification of Sediment Types Offshore of the Broadkill Beach, Delaware, Area |
JUL 96 |
127 pages |
| Authors:
Donald K. Stauble; Richard G. McGee; COASTAL ENGINEERING RESEARCH CENTER VICKSBURG MS
|
| Erosion is occurring along the shoreline of Delaware Bay, comprising the east coast within the state of New Jersey and the west coast within the state of Delaware. This erosion has resulted in a need to investigate the shallow offshore areas of the bay adjacent to both the Delaware and New Jersey coasts for use as borrow areas for beachfill material. The area is relatively unexplored from a geotechnical standpoint ... |
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| Sediment Penetration of Underwater Mammalian Sonar Signals |
13 JUN 96 |
11 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The objective is characterization of buried target detection by underwater mammalian sonars. To this end, a collaboration has been formed between Applied Research Laboratories, The University of Texas at Austin (AflL:UT) and Naval Command, Control and Ocean Surveillance Center (NRaD), San Diego. ARL:UT brings expertise in the modeling of sediment acoustics, and signal processing. NRaD possesses extensive experience in the training of mammals to locate buried objects, as well as ... |
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| A Model for Bistatic Scattering into Ocean Sediments for Frequencies from 10 - 100 kHz |
JUN 96 |
41 pages |
| Authors:
Kevin L. Williams; Darrell R. Jackson; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
|
| A model is developed for bistatic scattering into ocean sediments by an acoustic source located in the water and a receiver buried in the bottom. The model is closely related to that developed by Jackson (1993) for a source and receiver that were both located in the water and parallels that effort in many regards. In particular, bottom scattering is treated as being due to interface roughness and volume inhomogeneity. ... |
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| Modeled High-Frequency Acoustic Backscattered Levels from Range- Independent and Simplistic Range-Dependent Sand Bottoms |
21 FEB 96 |
17 pages |
| Authors:
Kristen D. Savage; Roger W. Meredith; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Results investigating the effects of variable bottom composition on modeled high-frequency backscattered levels are presented for a typical shallow- water, variable bottom (range-dependent) environment. The modeled environment consisted of a single sound speed profile, a flat sea bottom with range- dependent bottom composition, and a smooth, flat sea surface. Coarse-and fine- grained sandy areas were partitioned in range to create range dependence. Bottom backscattering and reflection loss for each partition ... |
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| 1993-94-95 Kara Sea Field Experiments and Analysis. 1995 Progress Report to ONR Arctic Nuclear Waste Assessment Program |
14 JAN 96 |
89 pages |
| Authors:
G. W. Phillips; R. A. August; S. E. King; D. K. Young; R. H. Bennett; NAVAL RESEARCH LAB WASHINGTON DC
|
| This progress report covers field work and laboratory analysis efforts for quantifying the environmental threat of radioactive waste released in the Arctic seas adjacent to the former Soviet Union and for studying the various transport mechanisms by which this radioactivity could effect populations of the U.S. and other countries bordering the Arctic. We obtained water, sediment, biological samples and oceanographic data from several cruises to the Kara Sea and adjacent ... |
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| Field Measurements of Local Pier Scour in a Tidal Inlet |
DEC 95 |
148 pages |
| Authors:
Wayne O. Walker; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Present design criteria and existing scour prediction models were developed primarily from the study of steady, homogenous, unidirectional flow. These models have been extensively reviewed and fine tuned, and for the riverine environment provide a good basis for the design effort. However, tidal flows are not normally unidirectional. A multitude of hydrodynamic processes affect these inlets and cause the current to alternate and change directions. Wind, waves, storm surge, runoff; ... |
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| NCPA Research Program, FY94 |
31 OCT 95 |
40 pages |
| Authors:
H. E. Bass; A. R. Kolaini; B. Denardo; J. M. Sabatier; JAMIE WHITTEN NATIONAL CENTER FOR PHYSICAL ACOUSTICS UNIVERSITY MS
|
| This report summarizes research performed at the Jamie Whitten National Center for Physical Acoustics during the period June 1, 1994 to May 31, 1995. Research on bubble related ambient noise in the ocean is a continuation of a long term research project into this phenomenon. Experimental investigation of an acoustic soliton is a new effort. The research into attenuation mechanisms in sediments attempts to apply past research expertise in propagation ... |
|
| Bottom Grain Gas and Roughness Technique (BOGGART) Version 1.0: Bottom Backscatter Model User's Guide |
02 OCT 95 |
42 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A use's guide for ARL:UT's marine sediment acoustic backscatter model has been developed. The model, named BOGGART (Bottom Grain Gas and Roughness Technique), is a three-component model which computes the total backscattering strength as an incoherent sum of contributions from three components. They are (1) scattering from sediment grains, (2) scattering from trapped gas bubbles within the sediment, and (3) scattering from interface roughness. The grain scattering is modeled empirically ... |
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| The Effects of Suspension of Cohesive Sediments on Shear Stress and Transport |
21 JUL 95 |
43 pages |
| Authors:
Scott Jenkins; Saima Aijaz; Douglas Inman; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
|
| The variability of rheological properties in fluid-mud suspensions is studied as a function of salinity and sediment concentration. It was found that the steady state shear stress increases exponentially with increasing sediment concentration and increases logarithmically with increasing salinity of the suspension. An analytic model predicting shear stress as a function of electroviscous properties is developed. The model shows that the effect of salts in the suspension is to decrease ... |
|
| Nonlinear Properties of In-Situ Sediment Gas Bubbles |
21 JUL 95 |
61 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
|
| A model for difference frequency backscatter from trapped bubbles in sandy sediments is developed. A nonlinear volume scattering coefficient is computed via a technique similar to that of Ostrovsky and Sutin ('Nonlinear sound scattering from subsurface bubble layers', in Natural Physical Sources of Underwater Sound, B. R. Kerman (ed.), 363-373 (1993)) which treats the case of bubbles surrounded by water. The Biot theory is incorporated to model the acoustics of ... |
|
| Estimation of Bottom Scattering Strength from Measured and Modeled AN/ SQS-53C Reverbation Levels |
JUN 95 |
204 pages |
| Authors:
Gary A. Scanlon; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Hamilton type geoacoustic models were developed for Area Foxtrot, a NUWC test bed for emerging active sonar systems where the surface sediment type is highly spatially variable. Reverberation levels (RL) were modeled using the FEPE propagation model to augment the GSM propagation model because the bottom loss model in GSM did not estimate transmission loss accurately in shallow water. FEPE estimates reveal there is over a 15 dB difference between ... |
|
| Geotechnical Properties of Six Closely Spaced Sites from Eckernfoerde Bay, Germany |
JUN 95 |
7 pages |
| Authors:
K. McCrocklin; M. Mayer; R. Bennett; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
|
| This study was conducted to observe the variability of geotechnical properties of shallow marine sediments collected in close proximity to one another. The sediment found in Eckernfoerde Bay was primarily soft, silty, organic clay. The site for collection was centered around a buoy located at 54 deg 29.88N and 9 deg 59.68E. From this reference point, six sites were chosen to form a circle and from each site 3, 3 ... |
|
| Multiple Scatter Theory of Ocean Sediments |
25 APR 95 |
6 pages |
| Authors:
Nicholas P. Chotiros; Dennis Yelton; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| To develop a new model of acoustic bottom backscatter from sandy sediments, based on a multiple scattering theory approach, and hence, properly explain observed phenomena, including Lambert's rule and frequency dependence of backscattering strength, particularly at shallow grazing angels, for which current theories are at a loss. (MM) |
|
| Southeast Texas Shelf Environment Off Port Isabel, Texas for the AA2 Exercise |
21 MAR 95 |
100 pages |
| Authors:
Bruce R. Gomes; James K. Fulford; George P. Cloy; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| During the fall of 1993, the Airborne Active Adjunct and Advanced Active Sonobuoy Experiment (AA2) was conducted off Port Isabel, Texas. The shelf in this area is dominated by a 9-m layer of clay with interlayered silts, and sands. Along most of the east-west track there is a strong subbottom reflector at an average of 5 m below the seafloor. Its disappearance coincides with higher clay content. North-south track records ... |
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| Geotechnical Site Investigations for Dredging Projects |
JAN 95 |
11 pages |
| Authors:
S. J. Spigolon; Jack Fowler; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| The objective of a geotechnical site investigation for a dredging project is to obtain the most complete and accurate estimate of the location, description, and dredgeability properties of the sediments to be dredged that is possible within the limits of available time and money and of practicality. This technical note offers guidance in the planning of a dredging site investigation and in the methods typically used for underwater geotechnical investigations. ... |
|
| Bottom Backscatter from Trapped Bubbles - II |
01 DEC 94 |
40 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A model for acoustic backscatter from trapped gas bubbles in sandy sediments was described in 'Bottom Backscatter from Trapped Bubbles'. In that model, trapped bubbles were assumed to scatter as if they were free bubbles in open water. In this report, the effects of bubble confinement in sediment pores on the resonance behavior of the bubble are accounted for. This is done by assigning the pore fluid an effective density ... |
|
| West Florida Shelf Environment for the Area Characterization Test I (ACT I) |
08 JUL 94 |
90 pages |
| Authors:
B. R. Gomes; J. E. Matthews; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| During 18 through 27 September 1992, a carefully controlled acoustic exercise, Area Characterization Test 1 (ACT 1) was conducted in the shallow- water West Florida Shelf area known as Florida Middle Ground under the auspices of the Undersea Warfare Office of the Advanced Research Projects Agency. The goal is to develop an acoustic detection capability in adverse ocean environments such as shallow-water areas of continental shelves. To accomplish this, environmental ... |
|
| Fluid Mud and Water Waves: A Brief Review of Interactive Processes and Simple Modeling Approaches |
JUL 94 |
94 pages |
| Authors:
Ashish J. Mehta; Say-Chong Lee; Yigong Li; FLORIDA UNIV GAINESVILLE DEPT OF COASTAL AND OCEANOGRAPHIC ENGINEERING
|
| A review of field and laboratory data indicated that bottom mud can appreciably damp surface water waves in coastal areas. The interactive feature is the ability of waves to fluidize bottom mud and sustain it in a fluidized state as long as the wave action continues. This report reviews iterative procedures and simple model approaches for studying the basics of the interaction between progressive water waves and a compliant mud ... |
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| Acoustic Propagation by Bottom Bounce Mode to the North East of Australia |
JUL 1994 |
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| Authors:
M. W. Lawrence; M. J. Bell; S. Prenc; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)
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| Underwater acoustic propagation measurements have been made to the north east of Australia, primarily in the Coral and Solomon Seas. A few measurements were made in the Tasman Sea. The resulting data set has been analysed to provide acoustic bottom loss as a function of frequency and grazing angle for a range of sites. The experiments and the analysis are described, together with the results. The variability from site to ... |
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| Management of Bottom Sediments Containing Toxic Substances: Proceedings of the U.S./Japan Experts Meetings (15th) Held in San Pedro, California on 19-21 November 1991 |
MAY 94 |
345 pages |
| Authors:
Thomas R. Patin; CORPS OF ENGINEERS FORT BELVOIR VA WATER RESOURCES SUPPORT CENTER
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| The 15th U.S./Japan Meeting on Management of Bottom Sediments Containing Toxic Substances was held 19-21 November 1991 in San Pedro, California. The meeting is held annually through an agreement with the U.S. Army Corps of Engineers and the Japan Ministry of Transport to provide a forum for presentation of papers and in-depth discussion on dredging and disposal of contaminated sediment. Contaminated sediments, Sedimentation, Dredging, Toxicology, Marine deposits. |
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OCEAN BOTTOM SOILS
