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Oceanic Engineering, IEEE Journal of

Issue 1 • Date Jan. 2006

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  • Table of contents

    Page(s): c1 - c4
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  • IEEE Journal of Oceanic Engineering publication information

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  • Effects of sound on the marine environment (ESME): an underwater noise risk model

    Page(s): 4 - 7
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    Effects of Sound on the Marine Environment (ESME) is a computer model of the effects of underwater sound on marine life. The modular design behind the ESME model is motivated by the sonar equation, with subcomponent models for characterization of the source, for modeling of sound transmission through a medium, and for receiver properties (e.g., hearing abilities, behavioral responses to sound, and receiver distribution and abundance). Each subcomponent of ESME is intended to capture the current state of understanding in the relevant scientific field and to be capable of being updated as the understanding in the field advances. ESME is envisioned to have three primary applications: 1) retrospective studies of historical data, 2) predictive modeling of anticipated outcomes from a given scenario of sound in a marine environment, and 3) prescriptive guidance for research investments and efforts that will likely have the greatest effect on increasing confidence in decisions about underwater sound use and its effects View full abstract»

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  • A software workbench for estimating the effects of cumulative sound exposure in marine mammals

    Page(s): 8 - 21
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    The U.S. Navy has initiated a multidisciplinary research and development program to study the Effects of Sound on the Marine Environment (ESME). As part of this effort, the Naval Research Laboratory (NRL) is developing a software workbench for estimating the effects of cumulative sound exposure on marine mammals. This paper describes the workbench, and presents some preliminary simulation results. The workbench integrates data sets and computer models contributed by researchers in the areas of oceanography, underwater acoustic propagation, and marine mammal physiology and behavior. Models are incorporated for simulating animal movement, for estimating the received acoustic time series along an animal's track, and for predicting temporary threshold shifts (TTSs) induced by acoustic exposure. TTS predictions are shown to be highly dependent upon both the environmental variables and the movement of the marine mammals View full abstract»

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  • Oceanographic and sound speed fields for the ESME workbench

    Page(s): 22 - 32
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    The authors describe the effort to provide three-dimensional global thermohaline and sound speed fields for use in the effects of sound in the marine environment (ESME) workbench suite of programs. The primary fields used are from the modular ocean data assimilation system (MODAS), developed by Fox et al. The system provides global thermohaline and sound speed fields on a daily basis using environmental inputs from the U.S. Navy as well as remote sensing of sea surface temperature and sea surface height. To examine the MODAS fields, the authors also used data from the Southern California Bight collected by the California Cooperative Fisheries Investigations as well as high-resolution hydrographic data collected over the continental shelf south of New England as part of the shelfbreak PRIMER experiment. MODAS performs well for features such as large-scale boundary currents and eddies but is more limited in resolving features such as shelfbreak and coastal fronts, which have small spatial and temporal correlation scales. Because of the considerable computational needs of other ESME modules and its use as a planning tool, the authors present a pragmatic approach for future applications View full abstract»

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  • Consideration of fine-scale coastal oceanography and 3-D acoustics effects for the ESME sound exposure model

    Page(s): 33 - 48
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    Results and recommendations for evaluating the effects of fine-scale oceanographic scattering and three-dimensional (3-D) acoustic propagation variability on the Effects of Sound on the Marine Environment (ESME) acoustic exposure model are presented. Pertinent acoustic scattering theory is briefly reviewed and ocean sound-speed fluctuation models are discussed. Particular attention is given to the nonlinear and linear components of the ocean internal wave field as a source of sound-speed inhomogeneities. Sound scattering through the mainly isotropic linear internal wave field is presented and new results relating to acoustic scattering by the nonlinear internal wave field in both along and across internal wave wavefront orientations are examined. In many cases, there are noteworthy fine-scale induced intensity biases and fluctuations of order 5-20 dB View full abstract»

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  • Modeling techniques for marine-mammal risk assessment

    Page(s): 49 - 60
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    Propagation modeling in the ocean may be said to be a fairly mature subject, with a number of reliable and efficient acoustic models freely distributed. However, acoustic modeling to predict effects of sound on marine mammals presents some particular challenges. Standard sonar models predict the mean power levels for static receivers. However, marine-mammal researchers have shown a strong interest in being able to predict the actual time series that a moving mammal would experience as it swims through an ensonified ocean. The time series can then be used to directly model auditory models of the mammalian ear. To do this properly requires attention to subtle Doppler effects. The authors present a Gaussian-beam-tracing method that handles all these issues. Another key element needed for such models is the ability to rapidly predict three-dimensional (3-D) acoustic fields for lots of source/receiver combinations. This problem arises in trying to choose optimal locations for navy exercises, considering also a variety of hypothesized mammal-migration patterns. The authors discuss a precomputation approach to solve this problem. Finally, they examine a technique to reduce the computation needed for the one-third octave transmission loss (TL) averages. The one-third octave average is often used as a metric for the assessment of risk to mammals. The brute-force solution to this problem requires propagation modeling at many frequencies in the band. Here, the authors develop a general relationship to replace those frequency averages with much more easily computed range averages. The novelty of this approach relative to the previous range-averaging techniques is that it extends those methods to the range-dependent conditions View full abstract»

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  • Sound sources and levels in the ocean

    Page(s): 61 - 75
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    The standard definitions found in the American National Standards on Acoustics are applied to common sound sources used in both underwater acoustics research and naval sonar system operation. Recommended metrics are quantified for both continuous and transient sources of sound. Standard definitions are reviewed with theoretical sound source models. Requisite metrics are derived and applied to examples of energy sources of sound, such as transients from a small omnidirectional explosive, an air gun, a light bulb, and a dolphin click. A generic quantitative model of surface ship sonar system emissions is developed. Active sonar transmissions are analyzed with the requisite quantitative metrics required to characterize these emissions. These results should be useful in environmental assessments, biological experiments, and the sonar system design View full abstract»

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  • A method for modeling marine mammal movement and behavior for environmental impact assessment

    Page(s): 76 - 81
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    Estimating the impact of anthropogenic sound on marine animals entails consideration of animal location in the vertical and horizontal planes and the behavior of the animal (e.g., breeding, foraging, migration) at the time of sound exposure. To approach more realistic impact estimates, the effects of sound on the marine environment (ESME) model incorporates a simulation program that permits fine-scale control over simulated marine animal (animat) movement and behavior. The simulation program, known as the Marine Mammal Movement and Behavior (3MB) module, provides user control over animats that is scaleable to available information about the species of concern. Movement and behavior is stochastically determined by sampling from distributions describing rates of movement in the horizontal and vertical planes, direction of travel, time at the surface between dives, time at depth, and time in and transition between behavioral states. Influence of behavior over each of the other distributions is permitted. As knowledge of marine animal behavior, movement, and ecology increases, the flexibility and level of control provided by such models will increase the potential for realistic impact estimates View full abstract»

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  • A database for the study of marine mammal behavior: gap analysis, data standardization, and future directions

    Page(s): 82 - 86
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    A relational database that contained published information on the diving behavior and/or movement patterns of marine mammals was compiled to facilitate a modeling effort of the Effects of Sound on the Marine Environment (ESME) program. A total of 448 references from reports, books, and peer-reviewed journal articles were obtained. The metadata describing each animal studied, location of the study, and equipment used were entered into the database as well as empirical data describing the diving behavior and movement patterns of each animal. In total, the database contained 1815 entries from 51 different marine mammal species or subspecies. The majority of animals were seals and sea lions with 1560 entries from 29 individual species. More than half the number of animals studied were from high latitude regions (e.g., Arctic and Antarctic). Other problem areas identified were: 1) Data reduction in summaries, 2) inability to easily summarize qualitative and quantitative data, and 3) lack of standardization in data reporting. A solution is to create a common access data archive where researchers contribute raw published or unpublished geospatially referenced data sets. This would improve access to original data sets with large volumes of data, which, overall, enhances the power to develop robust behavioral or ecological models that could help define critical habitats of marine mammals View full abstract»

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  • Middle-ear stiffness of the bottlenose dolphin tursiops truncatus

    Page(s): 87 - 94
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    Previous research on the cetacean auditory system has consisted mostly of behavioral studies on a limited number of species. Little quantitative physiologic data exists on cetacean hearing. The frequency range of hearing varies greatly across different mammalian species. Differences among species correlate with differences in the middle-ear transfer function. Middle-ear transfer functions depend on the mechanical stiffness of the middle ear and the cochlear input impedance. The purpose of this study was to measure the middle-ear stiffness for the bottlenose dolphin (Tursiops truncatus), a species specialized for underwater high-frequency hearing and echolocation. Middle-ear stiffness was measured with a force probe that applied a known displacement to the stapes and measured the restoring force. The average middle-ear stiffness in ten dolphin ears was 1.37 N/mum, which is considerably higher than that reported for most terrestrial mammals. The relationship between middle-ear stiffness and low-frequency hearing cutoff in Tursiops was shown to be comparable to that of terrestrial mammals View full abstract»

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  • Topographical distribution of lipids inside the mandibular fat bodies of odontocetes: remarkable complexity and consistency

    Page(s): 95 - 106
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    Odontocetes possess unusual and specialized mandibular fat bodies in and around their lower jaws. These tissues have been proposed to facilitate sound reception and are composed of unusual endogenously synthesized lipids. Little is known about how the topographical arrangement of the lipid molecules in these tissues influences sound reception. We examined the lipid composition of the mandibular fat bodies, using a fine-scale approach, on six specimens (representing four odontocete families). We show that odontocete jaw lipids exhibit a complex structural three-dimensional topography. Different odontocetes synthesize and deposit slightly different molecules, but the relative arrangement of the lipids within each head showed marked consistency. Mandibular fats of beaked whales were uniquely dominated by isolauric acid (i-12:0). In contrast, the dolphin and porpoise biosynthesized isovaleric acid (i-5:0), while the pygmy sperm whale deposited medium-length (10-14 carbons) straight-chain lipids. In all heads examined, the shortest and branched-chain ("i") fatty acids were concentrated in the center of the jaw fats, which connect intimately with the ears. We hypothesize that in odontocete jaws, this arrangement may serve to channel an incoming sound to the ears because sound travels slower through shorter branched-chain fatty acids than through longer straight-chain fatty acids View full abstract»

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  • Aerial and acoustic marine mammal detection and localization on navy ranges

    Page(s): 107 - 119
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    Acoustic monitoring and aerial visual surveys of marine mammal activity were conducted simultaneously at the Navy's Pacific Missile Range Facility near Kauai, HI, during times of both high- and low-whale density from February 2002 to March 2003. Specifically, recordings from the range's 24 broadband hydrophones were made during 11 of 16 "in-season" and during six of ten "off-season" aerial surveys. Basic acoustic detections consisted primarily of humpback whale calls and sperm-whale clicks, and those two species were also reported in the visual surveys. The relative number of acoustic detections roughly corresponded with the visual survey results throughout the year. The same acoustic data were also provided to a passive-acoustic-localization algorithm based on acoustic propagation models which generated estimates of sperm-whale movement through the range. The acoustic localizations are in close proximity in space and time to the visual observations of sperm whales. Verification of the model-based localization algorithm's accuracy was demonstrated in a controlled-source experiment at the Navy's Atlantic Undersea Test and Evaluation Center (AUTEC) range in the Bahamas where the recordings of sperm-whale clicks were broadcast and successfully tracked. The localization accuracy of the model-based technique and traditional hyperbolic techniques is compared. These results raise the possibility of using existing Navy assets to detect and track marine mammals, particularly during times when visual sighting conditions are not favorable, in efforts to minimize their exposure to underwater sound View full abstract»

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  • Acoustic detections of blue whale (Balaenoptera musculus) and fin whale (B. physalus) sounds during a SURTASS LFA exercise

    Page(s): 120 - 128
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    Acoustic data collected on the R/V Cory Chouest in February and March 1996 during an active operation of the U.S. Navy's surveillance-towed-array-sensor-system low-frequency-active (LFA) sonar were analyzed for blue whale (Balaenoptera musculus) and fin whale (B. physalus) sounds. Operational monitoring and mitigation protocols were implemented throughout the exercise to reduce the chances of an acoustic impact on marine mammals and sea turtles. The operational schedule did not include intentional "control" periods without transmissions but did include periods when the LFA sonar was not operating for other reasons (e.g., repairs). There were insufficient detections of blue whales for further analysis. Fin whale acoustic detection probabilities were calculated from the postprocessed data. A local-linear-regression analysis was used to compare fin whale detection probabilities from 2065 11-min intervals under conditions when the LFA sonar was and was not transmitting. There was an indication of a slightly higher probability of detecting fin whale sounds during periods when there were no LFA transmissions than during periods with transmissions. This may be the result of the following: 1) Reduced vocal activity by whales in response to LFA transmissions; 2) the effect of the mitigation protocols; or 3) some combination of 1) and 2). The data presently available do not allow one to distinguish definitively between these explanations, mainly because there were not enough data recorded for periods without LFA transmissions View full abstract»

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  • Inferences on seabed acoustics in the East China Sea from distributed acoustic measurements

    Page(s): 129 - 144
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    Low-frequency acoustic data acquired in the central East China Sea basin at two locations are analyzed for the purpose of making inferences on seabed acoustics. Previous geophysical studies indicate that the first sediment layer is composed of a fine to medium sand. The current analysis employs octave-averaged transmission loss (TL) versus range data and pressure time series generated from explosive sources. The TL and time series data were collected in locations separated by about 65 km during the same month of the year. Both locations are near the same longitude, with water depths of 100-120 m. A linear frequency dependence of the attenuation in the 25-800 Hz band, with or without sound speed dispersion, leads to a geoacoustic solution using the TL data consistent with a soft clay, and thus inconsistent with the existing geophysical data. However, seabed representations that allow for a nonlinear frequency dependence of the attenuation, such as a Kramers-Kronig dispersion relationship, a simplified six-parameter Biot description, and an empirical frequency power law of the attenuation, all give similar values of the attenuation as a function of frequency and sediment sound speeds that are consistent with the previous geophysical studies in the area. Geoacoustic solutions obtained with the TL inversions produce reasonably good fits to the measured time series data. Inversions of the time series indicate that the sound speed at the top of the sediment is lower as compared to the values estimated from the location where the TL data were acquired. While the data have significant limitations as to the information they contain on the properties of the seabed, the analysis aids in quantifying the sensitivity of geoacoustic inversion of acoustic data in shallow water littoral regions to assumptions about the frequency dependence of attenuation and sound speed View full abstract»

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  • On shallow-water bottom reverberation frequency dependence

    Page(s): 145 - 155
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    Determinations of bottom scattering strength in the decade below 1 kHz under downward refracting conditions have been made using acoustic reverberation and transmission data from the 2001 East China Sea Asian Seas International Acoustic Experiment (ASIAEX). The measurements were performed using explosive sources and receiving hydrophones in ship-suspended vertical-line arrays. The focus of this paper has been the dependence of bottom scattering strength on the frequency and characterization of the uncertainties associated with the extraction of scattering strength from reverberation. The derived bottom scattering strength gradually rises with frequency from 100-300 Hz and then more rapidly above 300 Hz. A potential explanation suggests that the frequency variation results from two scattering mechanisms, rough layer scattering at the low end of the band and sediment near-surface volume scattering at the high end. The spatial extrapolation of these results is explored by comparing them with similarly derived scattering strengths using data obtained under the Navy's Harsh Environments Program at a somewhat separated site (56 km) under environmental conditions similar to those during ASIAEX. In the ASIAEX analysis, it has been found that the largest source of uncertainty in the scattering-strength frequency dependence arises from persistence of finite-amplitude effects associated with the source signal View full abstract»

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  • System-orthogonal functions for sound speed profile perturbation

    Page(s): 156 - 169
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    Empirical orthogonal functions (EOFs) are typically derived from direct measurements of the sound speed profile (SSP) and they are orthogonal in regard to the statistics of the SSP uncertainty. Viewed from the output end of a particular sonar system, however, the effect of an error in one EOF is usually coupled with the effect of the error in another due to the strongly nonlinear relation between the SSP parameters and the system response. In this paper, a new set of basis functions, orthogonal in regard to sonar performance measure, is developed to characterize SSP perturbations. The performance measure used is the Cramer-Rao bound (CRB) for SSP expansion coefficients derived from a full-field random Gaussian signal model; a closed-form, analytical solution is obtained for both the range-independent and adiabatically range-dependent environments. The derived functions make the CRB matrix diagonal, decoupling the errors in the estimation of the expansion coefficients. Compared to the EOFs, the new set of basis functions depends on both the statistics of the sound speed uncertainty and the sound waveguide propagation property; it incorporates the measurement noise as well. The development makes possible the investigation of the relative significance of the individual basis functions in system response; it also provides a novel framework for optimum acoustic parameterization in adaptive rapid environmental assessment View full abstract»

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  • Multiple-input-multiple-output coherent time reversal communications in a shallow-water acoustic channel

    Page(s): 170 - 178
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    A recent time reversal (TR) experiment demonstrated that multiple foci can be projected from an array of sources to the same range but at different depths. This multiple input/multiple output process can potentially increase the information data rate. This paper presents experimental results of coherent TR communications (binary phase-shift keying, quaternary phase-shift keying, and 8-quadratic-amplitude modulation) at 3.5 kHz with a 1-kHz bandwidth where different messages were sent simultaneously to either two or three different depths at an 8.6-km range in a 105-m-deep water View full abstract»

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  • Experimental detection and reception performance for uplink underwater acoustic communication using a remote, in-air, acousto-optic sensor

    Page(s): 179 - 187
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    Covert communications between underwater and aerial platforms would increase the flexibility of surface and air vehicles engaged in undersea warfare by providing a new netcentric warfare communications capability and could have a variety of commercial and oceanographic applications. Research into an acousto-optic sensor shows promise as a means for detecting acoustic data projected toward the water surface from a submerged platform. The laser-based sensor probes the water surface to detect perturbations caused by an impinging acoustic pressure field. Experimental studies were conducted to demonstrate acousto-optic sensor feasibility for obtaining accurate phase preserved recordings of communication signals across the air-water interface. The recorded surface velocity signals were transferred to an acoustic communications receiver that used conventional acoustic telemetry algorithms such as adaptive equalization to decode the signal. The detected, equalized, and decoded bit error rate performance is presented for hydrostatic and more realistic, hydrodynamic water surface conditions View full abstract»

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  • Autonomous underwater vehicle-based concurrent detection and classification of buried targets using higher order spectral analysis

    Page(s): 188 - 199
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    This paper presents a processing concept for autonomous underwater vehicle (AUV)-based concurrent detection and classification (CDAC) of mine-like objects. In the detection phase, the AUV seeks objects of interest using a simple energy detector combined with a peak tracking mechanism. Upon detection, the processing mechanism changes to a higher order spectral (HOS) classification process. The system is demonstrated through theory, simulation and at-sea experiments to have promise in reducing the false alarm rate of mine detections. The HOS classification mechanism is also shown to have some benefit over classical spectral estimation in all cases. Components of the system concept were also demonstrated live onboard the AUV during the Generic Oceanographic Array Technology Sonar (GOATS 2002) experiment off the coast of Italy, while others are demonstrated using a comprehensive AUV sonar simulation framework View full abstract»

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  • System identification of open-loop maneuvers leads to improved AUV flight performance

    Page(s): 200 - 208
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    The authors focus on demonstrating a simple design procedure for the Odyssey III autonomous underwater vehicle (AUV) flight control system. This procedure can be carried out quickly and routinely to maximize vehicle effectiveness. A hydrodynamic model of the vehicle was first developed from theory and bench-top laboratory tests. Using this initial model, a controller was developed from basic principles. Then, using this initial controller to reach a desired typical operating condition, a very compact set of open-loop maneuvers was performed in the field. The vehicle model was optimized using the Nelder-Mead simplex method, and a revised controller was then implemented and tested successfully View full abstract»

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  • Hypothesis grids: improving long baseline navigation for autonomous underwater vehicles

    Page(s): 209 - 218
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    Navigation continues to fundamentally limit our ability to understand the underwater world. Long baseline navigation uses range measurements to localize a remote vehicle using acoustic time-of-flight estimates. For autonomous surveys requiring high precision navigation, current solutions do not satisfy the performance or robustness requirements. Hypothesis grids represent the survey environment capturing the spatial dependence of acoustic range measurement, providing a framework for improving navigation precision and increasing the robustness with respect to non-Gaussian range observations. Prior association probabilities quantify the measurement quality as a belief that subsequent observations will correspond to the direct-path, a multipath, or an outlier as a function of the estimated location. Such a characterization is directly applicable to Bayesian navigation techniques. The algorithm for creating the representation has three main components: Mixed-density sensor model using Gaussian and uniform probability distributions, measurement classification and multipath model identification using expectation-maximization (EM), and grid-based spatial representation. We illustrate the creation of a set of hypothesis grids, the feasibility of the approach, and the utility of the representation using survey data from the autonomous benthic explorer (ABE) View full abstract»

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  • Improved satellite ground resolution for sea-ice observation using an inversion method and a priori information

    Page(s): 219 - 229
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    The proposals made for improving ground resolution in satellite microwave radiometry primarily seek to sharpen the main beam and refine hardware. However, deformation and changes in electromagnetic characteristics with scanning still significantly affect the antenna patterns of large-aperture antennas. This paper proposes an advanced method with two improvements. The first improvement is related to the method used to obtain a point spreading function (PSF) filter at every spot of interest in the scanning footprint. The method estimates only a typical PSF of the footprint just below the satellite orbit and applies rotation by the angular change that occurs as the footprint moves and rotates with scanning. The second improvement is to introduce a projection onto convex sets (POCS) method into the iterative calculation to solve the inverse problem and to find the most likely estimate of ground information. Two pieces of a priori information are also introduced in the iteration to achieve rapid convergence and reasonable estimation: The brightness temperature of the ground surface is 1) smooth and 2) nonnegative. Correlations between estimated results are also taken between neighboring footprints after retrieval, and convergence is easily attained in the iteration. As no practical satellite data were available, an observational simulation was used as a case study at the lowest frequency (6.9 GHz), which has the poorest resolution. In this case study, ice margins were clearly retrieved by the algorithm when ice floes were 50 km or more apart. Irregularities like ringing, unreasonable undulation, or unreasonable values have occasionally appeared with the current method, but are absent with the proposed improved inversion method used in combination with a POCS method View full abstract»

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Aims & Scope

The IEEE Journal of Oceanic Engineering (ISSN 0364-9059) is published quarterly by the IEEE Oceanic Engineering Society (IEEE OES). The scope of the Journal is the field of interest of the IEEE OES, which encompasses all aspects of science, engineering, and technology that address research, development, and operations pertaining to all bodies of water. This includes the creation of new capabilities and technologies from concept design through prototypes, testing, and operational systems to sense, explore, understand, develop, use, and responsibly manage natural resources.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
N. Ross Chapman
School of Earth & Ocean Sciences
University of Victoria
3800 Finnerty Road
Victoria, BC V8P 5C2 Canada
chapman@uvic.ca