| Digital Nautical Chart |
NOV 92 |
9 pages |
| Authors:
James A. Hammack; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
 | As the Navy's lead laboratory in Mapping, Charting and Geodesy, the Naval Research Laboratory (NRL) was tasked by the Defense Mapping Agency (DMA) to develop a draft product specification for a Digital Nautical Chart (DNC) database. This paper describes the DNC database design, intended use, and prototype production schedule as of mid 1992. The DNC database is intended to be used in the Navigation Sensor System Interface (NAVSSI) aboard U.S. ... |
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| Understanding Global Climate Change with Ocean Acoustic Tomography and Models |
NOV 92 |
10 pages |
| Authors:
John L. Spiesberger; Daniel E. Frye; Harley E. Hurlburt; Mark A. Johnson; James J. O'Brien; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Paleoclimate inferred from the Vostok ice core provides tantalizing evidence that increases in atmospheric CO2 are dynamically linked with increases in atmospheric temperature (Jouzel et al., 1987; Barnola et al., 1987; Genthon et al., 1987). However, the mechanisms responsible for the temporal and spatial scales of the accompanying temperature change are not understood because, in part, the ocean's role is not well understood. New technology is required to see inside ... |
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| A Study of Pulse Scattering in a Waveguide |
26 Oct 1992 |
5 pages |
| Authors:
Michael K Broadhead; Michael F Werby; Hassan B Ali; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| The problem of the scattering of a continuous acoustic wave(CW)from a submerged object in a waveguide has received extensive treatment in the frequency domain, where phenomena associated with the resonant behavior of the object have been studied in detail. This paper concentrates on the time-domain interpretation of the scattering problem. Computation of the scattered field from an incident pulse, which requires calculations for many frequencies, is performed using a new ... |
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| A Large Moored Tripod Structure for the Deep Ocean |
21 OCT 92 |
11 pages |
| Authors:
Martin G. Fagot; Richard C. Swenson; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| A large, moored tripod oceanographic measurement was fabricated and deployed in the deep ocean. The structure was 5100 m high with a base footprint of 6190 m, all suspended by a single 6150-lb buoyant float. The three 6200-m- long legs contained environmental measurement instrumentation in the top 2150 m of each leg. A lightweight cable design facilitated storage, deployment, and retrieval of more than 27,700 m (15 nmi) of cable ... |
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| Critical Frequencies in Scattering from Submerged Elastic Shells |
Oct-1992 |
8 pages |
| Authors:
Michael F Werby; Hassan B Ali; Michael K Broadhead; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| In the process of scattering from submerged elastic shells, it is possible to excite many types of resonances. Among these are the lowest order symmetric and antisymmetric Lamb modes, and the waterborne waves, such as the pseudo-Stoneley resonances and the higher order symmetric and antisymmetric Lamb modes Si and Ai (i = 1, 2, 3, ...). the frequency at which these originate are referred to as critical frequencies. We establish ... |
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| An Assessment of the Effects of Sound Speed Fluctuations on Sound Propagation in Shallow Water Using a Perturbation Method |
Oct 1992 |
8 pages |
| Authors:
Michael F Werby; Hassan B Ali; Michael K Broadhead; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Scintillations in the intensity of an acoustic signal are a common feature of propagation of sound in the sea, manifesting temporal variability in the index of refraction (sound velocity) of the medium. In this paper, a recently developed high-order perturbation method is described and applied to the problem of sound propagation in the sea. The method uses a canonical solution (sound speed profile) to form a set of basis functions ... |
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| Least-Squares Time-Delay Estimation for Transient Signals in a Multipath Environment |
JUL 1992 |
10 pages |
| Authors:
R. J. Vaccaro; C. S. Ramalingam; D. W. Tufts; R. L. Field; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| The problem of estimating the arrival times of overlapping ocean- acoustic signals from a noisy received waveform that consists of scaled and delayed replicas of a deterministic transient signal is considered. It is assumed that the transmitted signal and the number of paths in the multipath environment are known, and an algorithm is developed that gives least-squares estimates of the amplitude and time delay of each path. A method is ... |
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| Finding Mesoscale Ocean Structures with Mathematical Morphology |
27 JUN 1992 |
11 pages |
| Authors:
Suzanne M. Lea; Matthew Lybanon; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| We introduce a technique to aid in interpreting infrared satellite images of the North Atlantic Ocean Gulf Stream region. Present interpretive methods are largely manual, require significant effort, and are highly dependent on the interpreter's skill. Our quasiautomated technique is based on mathematical morphology, specifically the image transformations of opening and closing, which are defined in terms of erosion and dilation. The implementation performs successive openings and closings at increasing ... |
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| Classification of Elastic Objects by Active Sonar in the Vicinity of Shallow Sea Boundaries |
APR 1992 |
15 pages |
| Authors:
Guillermo C. Gaunaurd; Michael F. Werby; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Active sonar classification of submerged elastic structures becomes increasingly difficult when the structure is close to the bottom or surface of the sea. The backscattering cross-section (BSCS) of any target, which is relatively simpler to determine in deep waters, away from boundaries, becomes substantially distorted as the structure approached either one of these environmental boundaries. Near these interfaces the classification methodology based on echo resonances that we have used in ... |
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| Digital Nautical Chart |
FEB 1992 |
12 pages |
| Authors:
James A. Hammack; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| The Defense Mapping Agency (DMA) has tasked the Naval Oceanographic and Atmospheric Research Laboratory (NOARL) to develop a product specification for a Digital Nautical Chart (DNC) database. The DNC will be used by the Department of Defense in nautical Electronic Chart Display and Information Systems. This paper will describe the structure and content of the DNC database. The DNC database will be implemented in DMA's Vector Product Format (VPF). VPF ... |
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| Physical Optics and Rigid/Soft Approximations to Forward Scattering by Elastic Shells |
92 |
14 pages |
| Authors:
Jacob George; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Our numerical results demonstrate that both Fraunhofer and Fresnel diffractions provide good approximations to forward scattering by elastic spherical shells and rigid/soft spheres, for nondimensional frequency values 20 |
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| Implementation of Custom Colors in the DECwindows Environment |
1992 |
9 pages |
| Authors:
Stephanie A. Myrick; Maura C. Lohrenz; Perry B. Wischow; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| This paper describes the implementation of user-defined, or custom, colors in the DECwindows environment. Custom colors can be used to augment the standard color set that is associated with the hardware colormap. The custom color set that is included in this paper consists of 240 distinct colors, each of which is comprised of red, green, and blue intensities. Intensify levels range from zero (no intensity) to 255 (maximum intensity). The ... |
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| Model Diffuse Attenuation Coefficient Profiles |
1992 |
6 pages |
| Authors:
L. Estep; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Light transport through water is controlled by the properties of dissolved substances, particulate matter, and water itself. The rate at which the light field decays can be measured by optical instrumentation and parameterized by the apparent optical property of the water, the diffuse attenuation coefficient, k. The diffuse attenuation coefficient is known to vary with depth near the surface. However, as the light field penetrates to greater depths, the value ... |
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| Sea Ice Altimetry |
1992 |
26 pages |
| Authors:
Florence M. Fetterer; Mark R. Drinkwater; Kenneth C. Jezek; Seymour W. Laxon; Robert G. Onstott; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Using altimeter data for quantitative information about sea ice is an idea with relatively few proponents. Often the poor spatial sampling given by the altimeter's single-point measurements along widely spaced ground tracks and the difficulty of interpreting altimeter pulse echoes over ice are cited as reasons to avoid altimetry. It is becoming evident, however, that altimetry may be able to make unique measurements. For instance, the altimeter data record reveals ... |
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| The Use of Satellite Observations in Ice Cover Simulations |
1992 |
21 pages |
| Authors:
Ruth H. Preller; John E. Walsh; James A. Maslanik; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| The combination of numerical models and observational data can provide a unique tool for studying the complex interactions of the atmosphere, the ice, and the ocean. The formulation of numerical ice and coupled ice-ocean- atmosphere models is based on our knowledge of dynamic and thermodynamic principles and how they relate to observed ice conditions. Field experiments such as the Arctic Ice Dynamics Experiment (AIDJEX) Pritchard, 1980 and the Marginal Ice ... |
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| Multispectral Image Enhancement Reveals Kuwaiti Oil Plumes |
1992 |
7 pages |
| Authors:
Thomas F. Lee; James Clark; Maureen Thompson; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Absorbing of incoming solar radiation at visible wavelengths, oil smoke is nearly invisible over water on many environmental satellite images. To improve the detectability of smoke, the authors construct bispectral composites from images from the NOAA Advanced Very High Resolution Radiometer (AVHRR). These composites are constructed from a ratio between AVHRR channels 1 and 2. While neither channel by itself shows smoke overwater, the ratio image often depicts smoke quite ... |
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| Electrochemical Techniques Applied to Studies of Microbiologically Influenced Corrosion (MIC) |
1992 |
16 pages |
| Authors:
Florian Mansfeld; Brenda Little; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Electrochemical techniques including measurements of corrosion potential, redox potential, polarization resistance, electrochemical impedance, electrochemical noise, polarization curves, and electrochemical hydrogen permeation techniques have been applied to studies of microbiologically influenced corrosion (MIC). Applications include evaluation of MIC of metals exposed to seawater, fresh water, demineralized water, process chemicals, food stuffs, soils, aircraft fuels, human plasma, and sewage. In this review electrochemical data from laboratory and field applications are presented and ... |
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| Dependence of Ocean Heating on the Distribution of Spectral Irradiance in the North Atlantic |
1992 |
12 pages |
| Authors:
Robert A. Arnone; Gregory E. Terrie; Paul J. Martin; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Subsurface heating rates from visible solar irradiance were computed for the North Atlantic for May 1979 during the period of the spring bloom. The visible spectrum between 400 and 700 nm accounts for a substantial fraction, about 43%, of the total solar irradiance at the sea surface, and comprises most of the solar irradiance that penetrates more than a meter into the sea. The mean monthly spectral diffuse attenuation coefficients ... |
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| Spectral and Spatial Variability of Solar Irradiance in the North Atlantic |
1992 |
15 pages |
| Authors:
Gregory E. Terrie; Robert A. Arnone; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| A model to predict the monthly solar irradiance incident at the ocean surface has been developed at seven wavelengths across the visible spectrum (390,440,490,540,590,640, and 690 nm). The model incorporates specific monthly climatological databases of aerosols, ozone, and percent cloud cover derived from satellite observation for the North Atlantic from May 1979. The variations in the spectral irradiance fields in the North Atlantic are shown to be highly spatially variable ... |
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| Hydrographic Section Across the Kuroshio Near 35 Degrees N, 143 Degrees E |
15 APR 1984 |
13 pages |
| Authors:
W. J. Teague; A. M. Shiller; Z. R. Hallock; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| A closely spaced conductivity-temperature-depth/hydrographic section was conducted off the east coast of Japan in July 1992. The southeastward section crossed the Japan Trench and the Kuroshio in the vicinity of the Kashima 1 seamount. Vertical sections of temperature, salinity, density, oxygen, and nutrients are discussed in conjunction with the movement and interleaving of water masses. Complicated vertical and horizontal mixings of water masses are inferred from the temperature and salinity ... |
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| An Expert Systems Technology Approach to Maintenance Proficiency |
54 |
8 pages |
| Authors:
Portia J. Harris; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Traditional maintenance training curricula use paper technical manuals to teach 'tricks of the trade' in corrective and preventive maintenance which require multiple adjustments, lengthy calibrations and labor intensive test/checkout procedures. Rotation often delays personnel assignment to a platform which requires these maintenance skills. The non-availability of skilled maintenance personnel poses a tremendous threat to readiness conditions for mission critical equipment. In order to best support the Navy's maintenance requirements and ... |
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