Dissertations / Theses on the topic 'Ocean mapping'
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Rikoski, Richard J. (Richard James) 1976. "Delayed stochastic mapping." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91338.
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Smith, Christopher Michael 1969. "Integrating mapping and navigation." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50047.
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Jakobsson, Martin. "Mapping the Artic Ocean : bathymetry and Pleistoce paleoceanography /." Stockholm : Department of geology and geochemistry, Stockholm university, 2000. http://catalogue.bnf.fr/ark:/12148/cb409769608.
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Rodriguez-Ortiz, Claudia Doria. "Automated bathymetry mapping using an autonomous surface craft." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39621.
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Kim, SungJoon 1970. "Efficient simultaneous localization and mapping algorithms using submap networks." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33448.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004.Includes bibliographical references (leaves 215-223).
Autonomous mapping of large-scale environments has been a critical challenge confronting researchers in mobile robotics. This thesis investigates two aspects of the large-scale simultaneous localization and mapping (SLAM) problem: (1) the behavior of the covariance matrix in the Kalman filter solution to the linear Gaussian SLAM problem, and (2) the development of new algorithms for efficient large-scale mapping. The key issue motivating study of the linear Gaussian SLAM problem is to understand the behavior of the uncertainty estimates with time. In this thesis, we provide an analysis of the asymptotic behavior of the full covariance SLAM solution. We present a novel generalized closed-form solution to the single degree-of-freedom SLAM problem (known as the MonoRob problem). We examine the cross correlation behavior for the case of observed and non-observed features, and show that a feature must be repeatedly reobserved for it to become fully correlated with other features. Additionally, we provide a new "tight" lower bound for the map uncertainty for a certain class of the MonoRob problem. The second part of the thesis develops new techniques for attacking the scaling problem in SLAM.
(cont.) The work builds on the Constant Time SLAM (CTS) method developed by Newman and Leonard, which is the first SLAM algorithm to achieve global convergence while maintaining consistent error bounds with an 0(1) growth of complexity for the linear Gaussian SLAM problem. Our work makes four contributions: (1) We describe a new algorithm, termed CTS 2.0, that achieves better performance than CTS while maintaining constant-time performance. (2) We present an alternative subnmap network SLAM algorithm, termed Network Optimized SLAM (NOS), that transfers information across submaps in O(n) time to achieve faster convergence than CTS while maintaining its desirable consistency properties. (3) we provide a theoretical and experimental analysis of CTS, CTS 2.0, and NOS and compare all three algorithms with the full covariance solution. (4) We perform an analysis of the erro:cr metrics for measuring the global uncertainty of a SLAM solution, yielding new insights into the behavior of this type of algorithm.
b y SungJoon Jim.
Ph.D.
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Hell, Benjamin. "Mapping bathymetry : From measurement to applications." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-57291.
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Surface elevation is likely the most fundamental property of our planet. In contrast to land topography, bathymetry, its underwater equivalent, remains uncertain in many parts of the World ocean. Bathymetry is relevant for a wide range of research topics and for a variety of societal needs. Examples, where knowing the exact water depth or the morphology of the seafloor is vital include marine geology, physical oceanography, the propagation of tsunamis and documenting marine habitats. Decisions made at administrative level based on bathymetric data include safety of maritime navigation, spatial planning along the coast, environmental protection and the exploration of the marine resources. This thesis covers different aspects of ocean mapping from the collection of echo sounding data to the application of Digital Bathymetric Models (DBMs) in Quaternary marine geology and physical oceanography. Methods related to DBM compilation are developed, namely a flexible handling and storage solution for heterogeneous sounding data and a method for the interpolation of such data onto a regular lattice. The use of bathymetric data is analyzed in detail for the Baltic Sea. With the wide range of applications found, the needs of the users are varying. However, most applications would benefit from better depth data than what is presently available. Based on glaciogenic landforms found in the Arctic Ocean seafloor morphology, a possible scenario for Quaternary Arctic Ocean glaciation is developed. Our findings suggest large ice shelves around parts of the Arctic Ocean during Marine Isotope Stage 6, 130–200 ka. Steered by bathymetry, deep water from the Amerasian Basin of the Arctic Ocean flows over the central Lomonosov Ridge into the Eurasian Basin. This water mass is traced on its continuing way towards Greenland and the Fram Strait. At the Morris Jesup Rise, bathymetry plays an important role in the partial re-circulation of the water into the Amerasian Basin.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Submitted.
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Kim, Kyung Cheol. "Calibration and validation of high frequency radar for ocean surface current mapping." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FKim.pdf.
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Roman, Christopher N. "Self consistent bathymetric mapping from robotic vehicles in the deep ocean." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/39184.
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Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 2005.Bibliography: p. 119-129.
Obtaining accurate and repeatable navigation for robotic vehicles in the deep ocean is difficult and consequently a limiting factor when constructing vehicle-based bathymetric maps. This thesis presents a methodology to produce self-consistent maps and simultaneously improve vehicle position estimation by exploiting accurate local navigation and utilizing terrain relative Measurements. It is common for errors in the vehicle position estimate to far exceed the errors associated with the acoustic range sensor. This disparity creates inconsistency when an area is imaged multiple times and causes artifacts that distort map integrity. Our technique utilizes small terrain "sub-maps" that can be pairwise registered and used to additionally constrain the vehicle position estimates in accordance with actual bottom topography. A delayed state Kalman filter is used to incorporate these sub-map registrations as relative position measurements between previously visited vehicle locations. The archiving of previous positions in a filter state vector allows for continual adjustment of the sub-map locations. The terrain registration is accomplished using a two dimensional correlation and a six degree of freedom point cloud alignment method tailored for bathymetric data.
(cont.) The complete bathymetric map is then created from the union of all sub-maps that have been aligned in a consistent manner. Experimental results from the fully automated processing of a multibeamn survey over the TAG hydrothermal structure at the Mid-Atlantic ridge are presented to validate the proposed method.
by Christopher N. Roman.
Ph.D.
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Dixon, John Patrick. "Found at Sea: Mapping Ships on the Eighteenth-Century Atlantic Ocean." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11696.
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"Found at Sea" is a historical study centered on the Atlantic Ocean. This dissertation employs ships' logbooks in combination with a GIS mapping methodology to address the ocean, itself, as a site for historical developments. Eighteenth-century mariners sailed the ocean in more varied ways than historians have previously described. This dissertation demonstrates that the Atlantic Ocean of the late eighteenth century was a highly-populated, very social, international space. It was normal for a ship to see another ship about half of the days while it was at sea. During peacetime these sightings could lead to friendly exchanges of news, food, and even spare parts in case of emergency. During wartime, shipping patterns adjusted to reflect new trading alliances and the threat of enemy vessels.
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Johannsson, Hordur. "Toward lifelong visual localization and mapping." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82350.
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Thesis (Ph.D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science; and the Woods Hole Oceanographic Institution), 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 171-181).
Mobile robotic systems operating over long durations require algorithms that are robust and scale efficiently over time as sensor information is continually collected. For mobile robots one of the fundamental problems is navigation; which requires the robot to have a map of its environment, so it can plan its path and execute it. Having the robot use its perception sensors to do simultaneous localization and mapping (SLAM) is beneficial for a fully autonomous system. Extending the time horizon of operations poses problems to current SLAM algorithms, both in terms of robustness and temporal scalability. To address this problem we propose a reduced pose graph model that significantly reduces the complexity of the full pose graph model. Additionally we develop a SLAM system using two different sensor modalities: imaging sonars for underwater navigation and vision based SLAM for terrestrial applications. Underwater navigation is one application domain that benefits from SLAM, where access to a global positioning system (GPS) is not possible. In this thesis we present SLAM systems for two underwater applications. First, we describe our implementation of real-time imaging-sonar aided navigation applied to in-situ autonomous ship hull inspection using the hovering autonomous underwater vehicle (HAUV). In addition we present an architecture that enables the fusion of information from both a sonar and a camera system. The system is evaluated using data collected during experiments on SS Curtiss and USCGC Seneca. Second, we develop a feature-based navigation system supporting multi-session mapping, and provide an algorithm for re-localizing the vehicle between missions. In addition we present a method for managing the complexity of the estimation problem as new information is received. The system is demonstrated using data collected with a REMUS vehicle equipped with a BlueView forward-looking sonar. The model we use for mapping builds on the pose graph representation which has been shown to be an efficient and accurate approach to SLAM. One of the problems with the pose graph formulation is that the state space continuously grows as more information is acquired. To address this problem we propose the reduced pose graph (RPG) model which partitions the space to be mapped and uses the partitions to reduce the number of poses used for estimation. To evaluate our approach, we present results using an online binocular and RGB-Depth visual SLAM system that uses place recognition both for robustness and multi-session operation. Additionally, to enable large-scale indoor mapping, our system automatically detects elevator rides based on accelerometer data. We demonstrate long-term mapping using approximately nine hours of data collected in the MIT Stata Center over the course of six months. Ground truth, derived by aligning laser scans to existing floor plans, is used to evaluate the global accuracy of the system. Our results illustrate the capability of our visual SLAM system to map a large scale environment over an extended period of time.
by Hordur Johannsson.
Ph.D.
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Toh, Kwang Yong Daniel. "Evaluation of surface current mapping performance by SeaSonde High Frequency radar through simulations." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Dec%5FToh.pdf.
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Wright, George C. "Validation of high frequency radar used in ocean surface current mapping via in-situ drifting buoys." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FWright.pdf.
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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Paduan, Jeffrey D. "September 2008." Description based on title screen as viewed on November 4, 2008. Includes bibliographical references (p. 85-86). Also available in print.
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Kunz, Clayton Gregory. "Autonomous underwater vehicle navigation and mapping in dynamic, unstructured environments." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71277.
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Thesis (Ph.D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and the Woods Hole Oceanographic Institution), 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 91-98).
This thesis presents a system for automatically building 3-D optical and bathymetric maps of underwater terrain using autonomous robots. The maps that are built improve the state of the art in resolution by an order of magnitude, while fusing bathymetric information from acoustic ranging sensors with visual texture captured by cameras. As part of the mapping process, several internal relationships between sensors are automatically calibrated, including the roll and pitch offsets of the velocity sensor, the attitude offset of the multibeam acoustic ranging sensor, and the full six-degree of freedom offset of the camera. The system uses pose graph optimization to simultaneously solve for the robot's trajectory, the map, and the camera location in the robot's frame, and takes into account the case where the terrain being mapped is drifting and rotating by estimating the orientation of the terrain at each time step in the robot's trajectory. Relative pose constraints are introduced into the pose graph based on multibeam submap matching using depth image correlation, while landmark-based constraints are used in the graph where visual features are available. The two types of constraints work in concert in a single optimization, fusing information from both types of mapping sensors and yielding a texture-mapped 3-D mesh for visualization. The optimization framework also allows for the straightforward introduction of constraints provided by the particular suite of sensors available, so that the navigation and mapping system presented works under a variety of deployment scenarios, including the potential incorporation of external localization systems such as long-baseline acoustic networks. Results of using the system to map the draft of rotating Antarctic ice floes are presented, as are results fusing optical and range data of a coral reef.
by Clayton Gregory Kunz.
Ph.D.
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Ayca, Aykut. "Development Of A Web Gis-based Tsunami Inundation Mapping Service." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614404/index.pdf.
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Tsunamis, as the catastrophic disasters, can cause loss of live and property when they come to the shores. Preparation of emergency plans is essential to reduce the damage. Consequently, any initiative in tsunami modeling and inundation mapping is of vital importance for progressing safety surveillance and maintenance.
In an effort to achieve a thorough analysis of effect of tsunami, it is critical to estimate the geographical extent of possibly affected area and to predict tsunami impacts. The inundation mapping system also must serve to manage the simulation data in a scalable environment to reach end-users in the time of event. For this purpose, in this study, the generation of a Web based Geographic Information System (GIS) to serve inundation maps through web.
The research methodology consists of four main stages: (i) simulating tsunamis based on six different scenarios (ii) processing simulation data through a GIS application(iii) development of web interfaces and implementation of the developed model for Web-GIS application
(iv) verification of the created model for Marmara Sea Region. The proposed system is expected to be an efficient tool for improving inundation mapping efforts for expected tsunamis in Turkey.
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Walter, Matthew R. "Sparse Bayesian information filters for localization and mapping." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46498.
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Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2008.Includes bibliographical references (p. 159-170).
This thesis formulates an estimation framework for Simultaneous Localization and Mapping (SLAM) that addresses the problem of scalability in large environments. We describe an estimation-theoretic algorithm that achieves significant gains in computational efficiency while maintaining consistent estimates for the vehicle pose and the map of the environment.We specifically address the feature-based SLAM problem in which the robot represents the environment as a collection of landmarks. The thesis takes a Bayesian approach whereby we maintain a joint posterior over the vehicle pose and feature states, conditioned upon measurement data. We model the distribution as Gaussian and parametrize the posterior in the canonical form, in terms of the information (inverse covariance) matrix. When sparse, this representation is amenable to computationally efficient Bayesian SLAM filtering. However, while a large majority of the elements within the normalized information matrix are very small in magnitude, it is fully populated nonetheless. Recent feature-based SLAM filters achieve the scalability benefits of a sparse parametrization by explicitly pruning these weak links in an effort to enforce sparsity. We analyze one such algorithm, the Sparse Extended Information Filter (SEIF), which has laid much of the groundwork concerning the computational benefits of the sparse canonical form. The thesis performs a detailed analysis of the process by which the SEIF approximates the sparsity of the information matrix and reveals key insights into the consequences of different sparsification strategies. We demonstrate that the SEIF yields a sparse approximation to the posterior that is inconsistent, suffering from exaggerated confidence estimates.
(cont) This overconfidence has detrimental effects on important aspects of the SLAM process and affects the higher level goal of producing accurate maps for subsequent localization and path planning. This thesis proposes an alternative scalable filter that maintains sparsity while preserving the consistency of the distribution. We leverage insights into the natural structure of the feature-based canonical parametrization and derive a method that actively maintains an exactly sparse posterior. Our algorithm exploits the structure of the parametrization to achieve gains in efficiency, with a computational cost that scales linearly with the size of the map. Unlike similar techniques that sacrifice consistency for improved scalability, our algorithm performs inference over a posterior that is conservative relative to the nominal Gaussian distribution. Consequently, we preserve the consistency of the pose and map estimates and avoid the effects of an overconfident posterior. We demonstrate our filter alongside the SEIF and the standard EKEF both in simulation as well as on two real-world datasets. While we maintain the computational advantages of an exactly sparse representation, the results show convincingly that our method yields conservative estimates for the robot pose and map that are nearly identical to those of the original Gaussian distribution as produced by the EKF, but at much less computational expense. The thesis concludes with an extension of our SLAM filter to a complex underwater environment. We describe a systems-level framework for localization and mapping relative to a ship hull with an Autonomous Underwater Vehicle (AUV) equipped with a forward-looking sonar. The approach utilizes our filter to fuse measurements of vehicle attitude and motion from onboard sensors with data from sonar images of the hull. We employ the system to perform three-dimensional, 6-DOF SLAM on a ship hull.
by Matthew R. Walter.
S.M.
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Baxter, Katrina. "Linking seafloor mapping and ecological models to improve classification of marine habitats : opportunities and lessons learnt in the Recherche Archipelago, Western Australia." University of Western Australia. School of Plant Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0181.
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[Truncated abstract] Spatially explicit marine habitat data is required for effective resource planning and management across large areas, although mapped boundaries typically lack rigour in explaining what factors influence habitat distributions. Accurate, quantitative methods are needed. In this thesis I aimed to assess the utility of ecological models to determine what factors limit the spatial extent of marine habitats. I assessed what types of modeling methods were able to produce the most accurate predictions and what influenced model results. To achieve this, initially a broad scale marine habitat survey was undertaken in the Recherche Archipelago, on the south coast of Western Australia using video and sidescan sonar. Broad and more detailed functional habitats types were mapped for 1054km2 of the Archipelago. Broad habitats included high and low profile reefs, sand, seagrass and extensive rhodolith beds, although considerable variation could be identified from video within these broad types. Different densities of seagrass were identified and reefs were dominated by macroalgae, filter feeder communities, or a combination of both. Geophysical characteristics (depth, substrate, relief) and dominant benthic biota were recorded and then modelled using decision trees and a combination of generalised additive models (GAMs) and generalised linear models (GLMs) to determine the factors influencing broad and functional habitat variation. Models were developed for the entire Archipelago (n=2769) and a subset of data in Esperance Bay (n=797), which included exposure to wave conditions (mean maximum wave height and mean maximum shear stress) calculated from oceanographic models. Additional distance variables from the mainland and islands were also derived and used as model inputs for both datasets. Model performance varied across habitats, with no one method better than the other in terms of overall model accuracy for each habitat type, although prevalent classes (>20%) such as high profile reefs with macroalgae and dense seagrass were the most reliable (Area Under the Curve >0.7). ... This highlighted not only issues of data prevalence, but also how ecological models can be used to test the reliability of classification schemes. Care should be taken when mapping predicted habitat occurrence with broad habitat models. It should not be assumed that all habitats within the type will be defined spatially, as this may result in the distribution of distinctive and unique habitats such as filterfeeders being underestimated or not identified at all. More data is needed to improve prediction of these habitats. Despite the limitations identified, the results provide direction for future field sampling to ensure appropriate variables are sampled and classification schemes are carefully designed to improve descriptions of habitat distributions. Reliable habitat models that make ecological sense will assist future assessments of biodiversity within habitats as well as provide improved data on the probability of habitat occurrence. This data and the methods developed will be a valuable resource for reserve selection models that prioritise sites for management and planning of marine protected areas.
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Jakuba, Michael Vavrousek 1976. "Stochastic mapping for chemical plume source localization with application to autonomous hydrothermal vent discovery." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38931.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2007.Includes bibliographical references (p. 313-325).
This thesis presents a stochastic mapping framework for autonomous robotic chemical plume source localization in environments with multiple sources. Potential applications for robotic chemical plume source localization include pollution and environmental monitoring, chemical plant safety, search and rescue, anti-terrorism, narcotics control, explosive ordinance removal, and hydrothermal vent prospecting. Turbulent flows make the spatial relationship between the detectable manifestation of a chemical plume source, the plume itself, and the location of its source inherently uncertain. Search domains with multiple sources compound this uncertainty because the number of sources as well as their locations is unknown a priori. Our framework for stochastic mapping is an adaptation of occupancy grid mapping where the binary state of map nodes is redefined to denote either the presence (occupancy) or absence of an active plume source. A key characteristic of the chemical plume source localization problem is that only a few sources are expected in the search domain. The occupancy grid framework allows for both plume detections and non-detections to inform the estimated state of grid nodes in the map, thereby explicitly representing explored but empty portions of the domain as well as probable source locations.
(cont.) However, sparsity in the expected number of occupied grid nodes strongly violates a critical conditional independence assumption required by the standard Bayesian recursive map update rule. While that assumption makes for a computationally attractive algorithm, in our application it results in occupancy grid maps that are grossly inconsistent with the assumption of a small number of occupied cells. To overcome this limitation, several alternative occupancy grid update algorithms are presented, including an exact solution that is computationally tractable for small numbers of detections and an approximate recursive algorithm with improved performance relative to the standard algorithm but equivalent computational cost. Application to hydrothermal plume data collected by the autonomous underwater vehicle ABE during vent prospecting operations in both the Pacific and Atlantic oceans verifies the utility of the approach. The resulting maps enable nested surveys for homing-in on seafloor vent sites to be carried out autonomously. This eliminates inter-dive processing, recharging of batteries, and time spent deploying and recovering the vehicle that would otherwise be necessary with survey design directed by human operators.
by Michael V. Jakuba.
Ph.D.
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Kilias, Estelle S. [Verfasser], Katja [Akademischer Betreuer] Metfies, Matthias [Akademischer Betreuer] Ullrich, Ulrich [Akademischer Betreuer] Bathmann, and Eva-Maria [Akademischer Betreuer] Nöthig. "Mapping the Genetic Diversity of Eukaryotic Protists in the Arctic Ocean / Estelle S. Kilias. Betreuer: Katja Metfies. Gutachter: Katja Metfies ; Matthias Ullrich ; Ulrich Bathmann ; Eva-Maria Nöthig." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/108125629X/34.
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Zelenke, Brian Christopher. "An empirical statistical model relating winds and ocean surface currents : implications for short-term current forecasts." Thesis, Connect to the title online, 2005. http://hdl.handle.net/1957/2166.
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Secchin, Nelio Augusto. "Mapeamento de habitats marinhos no banco dos Abrolhos." reponame:Repositório Institucional da UFES, 2011. http://repositorio.ufes.br/handle/10/2008.
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A plataforma continental tropical é composta por um mosaico de megahabitats que suportam uma alta diversidade de habitats, e atualmente vêm sofrendo com as pressões antrópicas. O desenvolvimento e a aplicação de geotecnologias em estudos de mapeamento do substrato marinho vêm proporcionando um aumento no conhecimento dos habitats bentônicos. Importante formação coralínea do Atlântico Sul, a Plataforma dos Abrolhos, não possui informações suficientes que possibilitem uma gestão efetiva. O presente estudo tem com objetivo apresentar uma distribuição espacial e caracterização dos domínios dos principais megahabitats da Plataforma dos Abrolhos. Para tal, foram utilizados dados diretos e indiretos de investigação geológica, com uma combinação metodológica englobando levantamentos de SVL, ecobatímetro monofeixe e ROV, sendo base para uma classificação hierárquica dos megahabitats e integração com dados pretéritos levantados. Alcançando uma representação interpretativa dos tipos de fundo da região estudada (50.500km²), a aplicação metodológica possibilitou gerar uma nova visão para a Plataforma dos Abrolhos. Foram identificados os domínios de megahabitat Recifal (17%), Rodolito (51%), bem como as principais feições de cada um, ocorrendo com variações na distribuição e ocorrência em relação à disposição ao perfil batimétrico. Uma estrutura recifal que ocorre juntamente com o domínio de rodolitos, as Buracas, é um habitat particular que pode ter uma importância significativa para o ecossistema de Abrolhos. A metodologia aplicada foi satisfatória na geração de uma representação da distribuição e descrição de megahabitats marinhos para toda a Plataforma dos Abrolhos. Oferecendo, assim, uma nova abordagem em estudos de delineamento de habitats marinhos aplicados na costa brasileira, sendo importante pela área espacial representada, contida em uma região singular onde havia uma lacuna no conhecimento sobre a distribuição e caracterização deste habitat em toda a sua extensão.
The continental shelf is composed of a tropical mosaic megahabitats that support a high diversity of habitats, and now have suffered from anthropogenic pressures. The development and application of geo-mapping studies of the marine substrate has provided increased knowledge of benthic habitats. The most important coral reef formation of the South Atlantic, Abrolhos Platform, does not have sufficient information to enable effective management. The present study aims at presenting a spatial distribution and characterization of the major fields of the Platform of the Abrolhos' megahabitats. To this end, we used data from direct and indirect geological research, with a combination of surveys covering methodological SSS, and echo sounder, ROV, and the basis for a hierarchical classification of megahabitats and integration with past data collected. Reaching an interpretative representation of the types of background of the region studied (50.500km²), the methodological application was able to generate a new vision for the Platform of the Abrolhos. We identified areas of reef megahabitat (17%), Rhodolite (51%) as well as the main features of each, with variations occurring in the distribution and occurrence in relation to the available bathymetric profile. A reef structures that occurs with the domain Rhodolite, the Buracas, is a particular habitat that may have a significant importance for the ecosystem of Abrolhos. The methodology was applied to generate a satisfactory representation of the distribution and description of marine megahabitats for the entire Abrolhos Platform. Thus offering a new approach to design studies of applied marine habitats along the Brazilian coast, is important for the space represented, contained in a unique region where there was a gap in knowledge about the distribution and characterization of this habitat throughout its length.
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Chenin, Pauline. "Unravelling the impact of inheritance on the Wilson cycle : a combined mapping and numerical modelling approach applied to the North Atlantic rift system." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAH001/document.
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Cette thèse analyse l’impact de l’héritage sur le Cycle de Wilson de l'Atlantique Nord via (1) la cartographie des structures orogéniques, et de l’architecture et l'évolution temporelle des rifts ; (2) une synthèse de l'architecture des systèmes de rift hyper-étendus ; (3) la modélisation numérique de l'effet d'un sous-plaquage magmatique sur un épisode de rift subséquent. Conclusions : (1) Les caractéristiques du rift Nord Atlantique diffèrent significativement entre les lithosphères Calédonienne et Varisque; (2) Deux types extrêmes de systèmes de rift : (a) étroits et immatures, dont la fermeture mène à une orogenèse contrôlée par des processus mécaniques ; et (b) larges et matures, dont les orogenèses sont affectées par des processus magmatiques; (3) Le sous-plaquage mafique de la croûte continentale et/ou l'existence de manteau appauvri à l'aplomb d'une ancienne zone orogénique peut empêcher la réactivation des faiblesses héritées et entraîner le boudinage de la croûte continentaleIn this thesis, I analyse the impact of inheritance on the Wilson Cycle in the North Atlantic: (1) I map the main orogenic structures, the first-order architecture of rift systems and the timing of major rifting events; (2) I synthesise the first-order architecture of rift systems; (3) I study, via numerical modelling, the impact of underplating on subsequent rifting. Conclusions: (1) The characteristics of the North Atlantic rift system vary significantly depending on whether it affects the Caledonian or Variscan orogenic lithosphere; (2) Two end-members for rift systems can be defined : (a) narrow and immature, whose closure results in orogenesis essentially controlled by mechanical processes; (b) wide and mature, whose closure and subsequent orogenesis is largely affected by magmatic processes; (3) Mafic underplating and/or mantle depletion beneath a former orogenic area may prevent the reactivation of the inherited weaknesses and may trigger the boudinage of the continental crust
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Derville, Solène. "Écologie spatiale des baleines à bosse en zone de reproduction : habitats, distribution et mouvements dans le Pacifique Sud." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS374.
Full textAbstract:
Comprendre les facteurs sociaux et environnementaux de la distribution et des mouvements de la mégafaune marine est essentiel à sa conservation. Les cétacés sont des espèces rares et mobiles, dont la gestion nécessite une meilleure compréhension des habitats qu’ils occupent. Cette thèse a eu pour but d’étudier l’écologie spatiale d’une population en danger de baleines à bosse (Megaptera novaeangliae) dans l’océan Pacifique Sud. En utilisant un ensemble de données multidisciplinaires collecté entre 1995 et 2018 en Nouvelle-Calédonie et en Océanie, cette thèse a poursuivi trois objectifs : 1) étudier les meilleures pratiques de modélisation de la distribution des cétacés, 2) acquérir une meilleure compréhension de la distribution, des habitats et des mouvements des baleines à bosse dans leur zone de reproduction d’Océanie, 3) prédire les zones de conservation prioritaires et les menaces potentielles pour les baleines à bosse dans cette région. La modélisation de la distribution d’une grande baleine migratrice à partir de données de recherche non systématique et issues de la science participative a fourni des prédictions de bonne qualité, tant que l’hétérogénéité spatiale de l’échantillonnage et la tendance statistique au surapprentissage étaient correctement prises en compte. Les modèles additifs généralisés ont été privilégiés pour leur équilibre en termes de complexité des relations modélisées, leur rendu écologiquement explicite et leur capacité de transferabilité. Les modèles d’utilisation de l’habitat à différentes échelles spatiales ont révélé une préférence pour une diversité d’habitats peu profonds répartis dans une large gamme de température des eaux en Océanie. Les monts sous-marins et bancs peu profonds ont été identifiés comme d’importants habitats de reproduction et de développement pour les baleineaux. Ces reliefs sous-marins jouent également un rôle clé dans la connectivité au sein et entre les populations. Cette utilisation unique et inattendue de l’habitat pélagique a des conséquences importantes sur la gestion spatiale des baleines à bosse. La prédiction des habitats de reproduction présents et futurs à des échelles multiples fournit une base scientifique pour la désignation de zones de conservation prioritaires et la protection contre les menaces générées par les activités humaines et le changement climatique dans le Pacifique SudUnderstanding the social and environmental drivers of the distribution and movements of marine megafauna is essential to their conservation. Cetaceans are elusive and mobile species, whose management requires an improved understanding of habitat use patterns. This thesis is aimed at investigating the spatial ecology of an endangered population of humpback whales (Megaptera novaeangliae) in the South Pacific Ocean. Using a multidisciplinary dataset collected between 1995 and 2018 in New Caledonia and Oceania, this thesis addressed three objectives, 1) investigate best practices to cetacean species distribution modeling, 2) acquire fundamental knowledge on the distribution, habitats and movements of humpback whales in Oceania breeding grounds, and 3) predict priority conservation areas and potential threats to humpback whales. Modeling the distribution of a migratory large whale from non-systematic visual survey and citizen science data provided valuable space-use predictions when uneven survey effort and statistical overfitting were specifically addressed. Generalized Additive Models were favored for their complexity trade-off, ecological interpretability and transferability. Models of habitat use revealed a preference for a diversity of shallow habitats (low island and atoll lagoons, barrier reef and high island slopes, banks and seamounts) spread over a relatively large thermal range over Oceania. Shallow seamounts and banks were identified as major breeding and nursing habitats and play a key role in the connectivity within and between populations. This unique and unexpected use of pelagic waters has important consequences for the spatial management of humpback whales. The predictions of present and future suitable humpback whale breeding habitats at multiples scales provide science-based evidence for priority conservation areas, and enable mitigation of threats from anthropogenic activities and climate change in the South Pacific
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LU, YA-HSIN, and 呂亞馨. "Implementing Concept Mapping to Evaluate College Students’ Ocean Literacy." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h58qzd.
Full textAbstract:
碩士國立臺灣海洋大學
地球科學研究所
107
The purpose of the study is to understand freshmen in the university regarding marine science concepts by using concept map method (open-ended tasks) and an open-ended question, and to assess their misconceptions about marine science concepts. A survey method was conducted on students from three departments of National Taiwan Ocean University(NTOU),Taiwan. In pre-test,a total of 305 samples was distributed, and a validity count of 294 was returned.In post-test,a total of 140 samples was distributed, and a validity count of 134 was returned.Using questionnaires as research instruments,the data were subject to concept mapping and SPSS statistics.The results of this study were as follows: 1.The answers provided by the students of NTOU with the assistance of propositional concept maps showed the average mark 63.07 out of 150,indicating only a basic understanding of marine science concepts among these students. 2.The first three terms "Submarine Volcano", "Mid-Ocean Ridge", and "Ocean currents" were the most commonly used by students to express marine science concepts. The first term "Submarine Volcano" was 131 times.The other two terms "Mid-Ocean Ridge" and "Ocean currents"appearred 126 and 113 times, respectively. 3.The marine concepts were more knowledge-oriented in the cognitive domain than attitudes and affective domains.We also observed the knowledge-oriented(46.4%), the affective-oriented(16.0%), the attitude-oriented(11.6%), and misconception-oriented(5.2%). 4.The scores of the post-test propositional concept maps were higher than that of pre-test. Therefore, it’s helpful to the ability of marine sciences that students attend in the class of Introduction to Environmental Science Related to Marine. The total scores of ME were t=-3.166,p<0.01, and the total scores of MM was t=-4.092,p<0.001. 5.The marine science concepts we provided were mostly accuracy-oriented.In accuracy-oriented, the scores of CSE was t=-4.752,p<0.001, the scores of CSE was t=-4.814,p<0.001, and the scores of MM was t=-5.950,p<0.001. 6.The three marine words "Submarine Volcano","Oceanic trench" and "Plate" were most frequently misconstrued by students. 7.The most misconceived statement of the marine misconception assessment was "the relative connections of submarine volcanoes, plate, and mid-ocean ridges","salinity of the ocean","depth of the oceanic trench", and "the difference between tides and ocean currents". The study can assist researchers and higher education in improving the quality and effectiveness of infusing marine education into curricula and promote ocean literacy.
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Li, Yun-Wen, and 李允文. "Shallow-Water Acoustic Mapping of Ocean Currents Using Towed Transceivers." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/75360865341812276284.
Full textAbstract:
碩士國立臺灣大學
海洋研究所
104
This study uses four moored {acoustic transceivers (a device consisting of a source and a receiver)} along with one towed by a ship to demonstrate the acoustic mapping of ocean currents with the mobile station in a shallow-water environment. The basic principle of the acoustic mapping for currents is that the difference in the travel times (DTT) of oppositely traveling acoustic signals is proportional to the integrated current velocity along the acoustic ray path. Thus the currents can be estimated with the DTT data. When the towed transceiver is incorporated, the acoustic signal is Doppler-distorted and the DTTs are affected due to the relative instrument motion. Since the transmitted signal, $m$-sequence, is highly sensitive to Doppler, the method based upon the delay-Doppler ambiguity function can determine the Doppler shift and the arrival patterns simultaneously. For the estimation of DTT, the conventional approach using the peak-picking method is subject to the uncertainties in identifying and resolving acoustic rays in the shallow-water environment. Hence, this study proposed a method based on the cross-correlation function (CCF) of the reciprocal arrival patterns. Ideally, the DTT could be obtained by the lag time corresponding to the maximum correlation. However, due to the multiple acoustic arrivals the CCF exhibits multiple peaks with similar heights. To address this issue, we utilize the time-evolving CCFs to select appropriate peaks for the determination of DTT. Using the data collected at Sizhiwan Marine Test Field, Kaohsiung, in September of 2015, the current field was estimated. The towed transceiver in the experiment provided additional reciprocal travel-time data for sensing the water volume at many angles and increased the coverage of the mapping area. Besides augmenting the number of DTT data for the current estimate, some of the data from the towed transceiver are used to validate the estimated field. The experiment site is dominated by the semi-diurnal tidal currents with the principal current direction flowing {along the isobaths}. The time evolution of the estimated current agrees well with the shipboard-ADCP measurements, and the spatial variations are observed when the currents change the direction.
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Gloege, Lucas. "Global Ocean Carbon Dioxide Flux Mapping Techniques: Evaluation, Development, and Discrepancies." Thesis, 2020. https://doi.org/10.7916/d8-j3p1-tf92.
Full textAbstract:
Atmospheric CO₂ is projected to increase for the foreseeable future. The amount of CO₂ that remains in the atmosphere is regulated, in large part, by the ocean. As the long-term response to the changing atmospheric pCO₂ unfolds, the ocean sink will continue to be modified on seasonal to decadal timescales by climate variability and change. The magnitude of this variability is an active area of research. Accurately quantifying this variability is a challenge given the paucity of direct in-situ observations. In order calculate the global air-sea CO₂ sink, ocean pCO₂ needs to be known, or at least accurately estimated, at all locations at regular intervals. Two approaches to estimate air-sea CO₂ flux are, 1) from simulations of the Earth system and 2) data gap-filling mapping techniques. The goals of this thesis are to 1) rigorously quantify errors in a leading pCO₂ and ocean CO₂ sink mapping technique and 2) to evaluate the efficacy of adding Earth system model based estimates of ocean pCO₂ as a first guess into machine learning based mapping techniques. To meet the first goal, we use a suite of Large Ensemble model members as a testbed to evaluate a leading pCO₂ gap-filling approach (SOM-FFN). We find that the SOM-FFN performs well when sufficient data is available, but overestimates Southern Ocean decadal variability by about 39%. To meet our second goal, we incorporate Earth system model pCO₂ output into machine learning techniques either by adding the output as an additional feature or by post-processing the model output by learning the misfit (misfit=observation-model) and correcting for it. We find that blending model output and observations using machine learning marginally improves prediction accuracy. In addition, we discuss the potential of the learned misfits as a new model diagnostic tool, which can be used to visualize spatiotemporal pCO₂ estimates. Taken together, this study has significant implications in the development of carbon monitoring systems, in turn aiding policy making and improving our understanding of the evolution of the air-sea CO₂ sink.
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Wang, Li-Nong, and 王立農. "Refined Doppler Centroid Estimation in Spaceborne SAR For Mapping Ocean Current Velocity." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/60032852448362348548.
Full textAbstract:
碩士國立中央大學
太空科學研究所
99
ADCP(Acoustic Doppler Current Profiler) is the most common method to obtain the ocean current information. However, in order to obtain sufficient spatial resolution of the current-data, it is rather expensive both in time and cost. Theoretically, it is possible to extract the surface target velocity from the Doppler shift embedded in SAR phase history in which the azimuth frequency shift is related to the motion of surface target in the radial direction. In this thesis, Correlation Doppler Estimation(CDE) was used to compute the baseband Doppler centroid by varying window size. The SAR data was acquired by ERS-2 satellite. It should be noted that the Doppler effects due to the satellite altitude variations and Earth rotation, among others, were correctly removed. By doing so, the Doppler shift is carefully checked against relative stationary ground surfaces which basically induce zero Doppler shift. The current velocity is then converted from Doppler shift. It is found that the CDE method is reasonably accurate over the homogeneous scene, like the ocean surface. The larger the window size we used, the lower the standard deviation is at cost of spatial resolution. Experimental results show that detection of the variations of current field using SAR is highly possible at relatively large scale observation.
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Wang, Chien-hsiung, and 王建雄. "Applying Concept Mapping to Explore the Management Strategy for Ocean Freight Forwarders in Taiwan." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5ha2k2.
Full textAbstract:
碩士國立高雄第一科技大學
運籌管理研究所
105
The purpose of this research is to explore management strategy in ocean freight forwarders. There are a large number of ocean freight forwarders, and competition is intense, to avoid price competition, to strengthen the core competence and the integration of resources, and set up appropriate management strategy. We used concept mapping to conduct our study and invited ten experts for brain-storming to extract their professional opinions and ideas with the question of “What are the factors that influence management strategy for ocean freight forwarders?” Then we implemented multivariate statistical analysis to quantify the data. After the analysis, we obtained 21 factors and five clusters, ‘category of products.’,‘service quality’,‘sales core ability’,‘sale core ability’,‘corporate image’,‘financial ability’,The three clusters ‘category of products.’, ‘service quality’,‘sales core ability’ of this research are the most important.The results of this study may provide a reference for ocean freight forwarders to management strategies.
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Tu, Yi-Chen, and 涂以蓁. "A Survey of Curriculum Mapping in Higher Education: Take National Taiwan Ocean University as An Example." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/k25r9b.
Full textAbstract:
碩士國立臺灣海洋大學
教育研究所
101
The purpose of this thesis is to resolve the problems found within the executing of the curriculum map of National Taiwan Ocean University (NTOU), explaining the structure of the NTOU curriculum map through an official faculty’s point of view, and possible paths to be taken in the future. The method of this study is survey research which the target is the administrators in NTOU who is in charge of executing curriculum map. Totally thirteen members were selected from the convenience sampling, and semi structured interview was used to investigate the options and suggestions from the sample members. The results of the research are concluded into six main points: 1.Application of curriculum map is benefit for departments and institutes to review of current curriculum. 2.The support from school members enhances the construction of curriculum map. 3.Curriculum map should be designed to fit the characteristics of schools. 4.Graduate attributes will help students to develop career planning. 5.Executives have limited authority to use curriculum map system, and cause the difficulty of construction. 6.The different cognition of every department and institute executives influences the construction of the curriculum map. According to the results of the research and further discussion, this research provides related advice for future application of curriculum mapping for higher education. Key words: Curriculum Mapping, Higher Education, National Taiwan Ocean University.
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Higginson, Simon. "Mapping and understanding the mean surface circulation of the North Atlantic: Insights from new geodetic and oceanographic measurements." 2012. http://hdl.handle.net/10222/14866.
Full textAbstract:
The mean dynamic topography (MDT) of the ocean is closely related to the mean surface
circulation. The objective of this thesis is to produce estimates of the MDT for the North
Atlantic using newly available data from ocean and gravity observing systems, to evaluate
these new estimates and so improve our understanding of the circulation.
Oceanographic estimates of the MDT are based on the mean temperature and salinity
(TS) fields of the ocean. These are typically averages from sparse observations collected
over many decades. The ocean is a non-stationary system so it is more appropriate to define
the mean for shorter, specific periods. Whilst the Argo observing system has increased the
frequency and resolution of in situ oceanographic measurements, high frequency (eddy)
variability remains. A new technique is described for removing this variability using
satellite altimeter measurements of the sea surface height. A new TS mean is produced,
relating to the period from 2000 to 2007, and this is used to map a new oceanographic
estimate of the MDT using an ocean circulation model.
New geodetic estimates of the MDT are produced using geoid models that incorporate
gravity measurements from the ongoing GRACE and GOCE satellite missions. These
are compared with the new oceanographic estimate and validated against independent
observations such as drifter speeds. The geodetic method produces realistic estimates of
the mean surface circulation, thereby realizing the long time dream of oceanographers to
observe the ocean circulation from space. The new oceanographic estimates are not as
accurate, but the new TS mean contributes to improvements in the performance of ocean
models, a necessary step in understanding and predicting the oceans.
Coastal tide gauges can provide an accurate estimate of the alongshore tilt of the coastal
MDT and this has been used to evaluate the above estimates. Temporal variability of the tilt
along the coast of the South Atlantic Bight is used, with statistical methods and an ocean
circulation model, to identify the processes contributing to the tilt. A new opportunity to
use tide gauges as part of an observing system for the ocean circulation is discussed.
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Kim, Hyun-Seung. "Mapping crustal structure of the Nechako Basin using teleseismic receiver functions." Thesis, 2010. http://hdl.handle.net/1828/3158.
Full textAbstract:
This thesis describes a passive-source seismic mapping project in the Nechako Basin of central British Columbia (BC), Canada, with the ultimate goal of assessing the hydrocarbon and mineral potential of the region. The Nechako Basin has been the focus of limited hydrocarbon exploration since the 1930s. Twelve exploratory wells were drilled; oil stains on drill chip samples and the evidence of gas in drill stem tests attest to some hydrocarbon potential. Seismic data collected in the 1980s were of variable quality due mainly to effects of volcanic cover in this region. For the present study, an array of nine seismic stations was deployed in 2006 and 2007 to sample a wide area of the Nechako Basin and map the sediment thickness, crustal thickness, and overall geometry of the basin. This study utilizes recordings of about 40 distant earthquakes from 2006 to 2008 to calculate receiver functions, and construct S-wave velocity models for each station using the Neighbourhood Algorithm inversion. The surface sediments are found to range in thickness from about 0.8 to 2.7 km, and the volcanic layer below ranges in thickness from 2.3 to 4.7 km. Both sediments and volcanic cover are thickest in the central part of the basin. The average crustal thickness across the basin is about 30-32 km; it is thicker in the northern and western parts of the basin, and thinner in the southern and eastern parts. This study complements other research in this region, such as independent active-source seismic studies and magnetotelluric measurements, by providing site-specific images of the crustal structure down to the Moho and detailed constraints on the S-wave velocity structure.
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Shan-BoYang and 楊善博. "Integrating evolutionary optimization and ocean color semi-analytical model for mapping Secchi disk depth of inland water from high resolution multispectral satellite data." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/zz4aux.
Full textAbstract:
碩士國立成功大學
環境工程學系
105
The measurement of Secchi disk depth to quantify the clarity (transparency) of water is the most direct and fast way, and most of reservoirs in Taiwan which was identified as the eutrophic reservoir because of low transparency. Transparency must be based on science as the background combined the water optical theory and physical model of transparency to explore the impact of domestic reservoir transparency of the key factors. Therefore, this study was corrected the semi-analytical transparency (SA-SD) model to figure out optimum decision variables by using genetic algorithm. After the pattern verification, the log-R2 is 0.73, and drew a comparison between Carlson's experimental algorithm, and the stepwise regression, the log-R2 is 0.07 and 0.71, respectively. The results showed that the SA-SD model of this study have higher accuracy than the general regression models. The remote sensing of inland water body mostly through the empirical relationship method of measuring the transparency in the past. In this study the results found that the domestic reservoir of radiative attenuation coefficient (Kd) and the surface radiation reflectance (rw) which tr and pc wavelength are located in the green band. So this study attempts to use Landsat 8 and Sentinel 2A high resolution multispectral satellite images, using green band Kd and rw as input product through the new transparent physical model for mapping Secchi disk depth of eight reservoirs.
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Idris, Nurul Hazrina. "Development of new retracking methods for mapping sea levels over the shelf areas from satellite alimetry data." Thesis, 2014. http://hdl.handle.net/1959.13/1051125.
Full textAbstract:
Research Doctorate - Doctor of Philosophy (PhD)Through research carried out in the last few years, sea level anomalies (SLAs) from altimeter range measurements have been improved in the near coastal zone between 50-10 km from the coastline using waveform retracking techniques. However, closer than about 10 km from the coastline, the improvement of altimetry data accuracy is still challenging due to the complex nature of the coastal topography and rougher coastal sea states. Although there is a healthy diversity of waveform retracking algorithms that have been beneficial to the coastal community, there is a lack of clear recommendations and guidelines on which retracker should be used under the various conditions. This dissertation presents a waveform retracking system that improves the accuracy of coastal altimetry data through the optimal selection and seamless switching of retrackers. The principles of the system are twofold. The first is to reprocess altimeter waveforms using the optimal retracker, which is sought, based on the analysis from a fuzzy expert system. The second is to minimise the relative offset in the retrieved SLAs caused by switching from one retracker to another, using a neural network. With the retracking system, the risk of assigning the waveform to an inappropriate retracker is minimised by including information about the waveform shapes and statistical features of the retracking results in the fuzzy expert system. The system also reduces inconsistency in the retracked SLAs when switching retrackers by employing the neural network to handle the nonlinear relationship between the retracker and the scattering surface, thus providing seamless transition from the open ocean to coast, or vice versa. The retracking system has been demonstrated to 20 Hz waveforms of Jason-1 and Jason-2/OSTM missions from 2009 to 2011. It has been applied to areas of the Great Barrier Reef in Australia and the Prince William Sound in Alaska. The regional investigations have demonstrated that the retracking system can effectively improve the quality of the altimeter derived SLAs in coastal regions. It reduces the standard deviation of the unretracked sea levels by up to 500 cm for Jason-1 and 300 cm for Jason-2. It extends the SLA profiles further (1-7 km) to the coastline and recovers up to 70% more data than the existing retrackers from the Sensor Geophysical Data Records(SGDR). Comparison with the SLAs from the tide gauges indicates that the SLAs from the retracking system are more reliable than those of from the SGDR products, in the sense that it has a higher (>0.8) temporal correlation and smaller (<17 cm) RMS errors. The retracked SLAs from the retracking system also produce reliable geostrophic velocities as they are consistent with those of the high frequency radar velocities in the Great Barrier Reef region. Comparison with the Regional Ocean Modelling System (ROMS) at Prince William Sound shows good agreement between the SLA patterns from the retracking system and the ROMS. The results obtained in this dissertation, therefore, present a significant improvement in the accuracy and precision of the estimated SLAs and efficiently reduce the altimetry no-data gap in coastal regions. In addition, it also addresses the systematic validation protocol for validating the altimetry retracked SLAs using the HF radar in the region of the Great Barrier Reef, and using the ROMS in the region of Prince William Sound.
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Boyer, Leanna. "Community participation in habitat mapping : learning through the emergence of an eelgrass stewardship network." Thesis, 2006. http://hdl.handle.net/1828/1745.
Full textAbstract:
This thesis explores learning in and through the emergence of a network of communities who participated in the B.C. Coastal Eelgrass Stewardship Project (the Project). I draw on a two-year ethnographic investigation of 20 community groups who were trained to map and monitor eelgrass habitat and carry out education and stewardship-related activities.
People from a multitude of backgrounds, including scientists and non-scientists, and a diversity of places, from small coastal communities to urban centers, worked towards the collective goal of mapping and conserving the extent of eelgrass habitat along the coast. Using cultural-historical activity theory, I develop an alternative framework for understanding learning and change in a network of communities. The collection of three main chapters, shows that learning, emergence, and stabilization of the network arose through the following dialectical relations: individual/collective, social/material, and agency/structure. This thesis shows that viewing and supporting the Project as a dynamic learning network makes it more stable.
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O'Neill, Jennifer D. "Mapping of eelgrass (Zostera marina) at Sidney Spit, Gulf Islands National Park Reserve of Canada, using high spatial resolution remote imagery." Thesis, 2010. http://hdl.handle.net/1828/3207.
Full textAbstract:
The main goal of this thesis was to evaluate the use of high spatial remote imagery to map the location and biophysical parameters of eelgrass in marine areas around Sidney Spit, a part of the Gulf Islands National Park Reserve of Canada (GINPRC). To meet this goal, three objectives were addressed: (1) Define key spectral variables that provide optimum separation between eelgrass and its associated benthic substrates, using in situ hyperspectral measurements, and simulated IKONOS and Landsat 7ETM+ spectral response; (2) evaluate the efficacy of these key variables in classification of the high spatial resolution imagery, AISA and IKONOS, at various levels of processing, to determine the processing methodology that offers the highest eelgrass mapping accuracy; and (3) evaluate the potential of ―value-added‖ classification of two eelgrass biophysical indicators, LAI and epiphyte type.
In situ hyperspectral measurements acquired at Sidney Spit in August 2008 provided four different data sets: above water spectra, below water spectral profiles, water-corrected spectra, and pure endmember spectra. In Chapter 3, these data sets were examined with first derivative analysis to determine the unique spectral variables of eelgrass and associated benthic substrates. The most effective variables in discriminating eelgrass from all other substrates were selected using data reduction statistics: M-statistic analysis and multiple discriminant analyses (MDA). These selected spectral variables enabled eelgrass classification accuracy of 98% when separating six classes on above water data: shallow (< 3 m deep) eelgrass, deep (> 3 m) eelgrass, shallow sand, deep sand, shallow green algae, and spectrally deep water. The variables were located mainly in the green wavelengths, where light penetrates to the greatest depth: the slope from 500 – 530 nm, and the first derivatives at 566 nm, 580 nm, and 602 nm. The same data were classified with 96% accuracy after correcting for the water column, using the ratios 566:600 and 566:710. The only source of confusion for all data sets was between green algae and eelgrass, presumably due to their similar pigment composition. IKONOS and Landsat 7ETM+ simulated datasets performed similarly well, with 92% and 94% eelgrass classification accuracy respectively.
In Chapter 4, the efficacy of the selected features was tested in the classification of airborne hyperspectral AISA imagery and satellite platform multispectral IKONOS imagery, and compared with various other classifiers, both supervised and unsupervised: K-means, minimum distance (MD), linear spectral unmixing (LSU), and spectral angle mapper (SAM). The selected features achieved the highest eelgrass classification accuracies in the study, when combined with atmospheric correction, glint correction, and optically deep water masking. AISA achieved eelgrass producer and user accuracies of 85% in water shallower than 3 m, and 93% in deeper areas. IKONOS achieved 79% for shallow waters and 82% for deep waters. Endmember classification also showed accuracies over 84% and 71% in AISA and IKONOS imagery respectively. Again, the largest source of confusion was between eelgrass and green algae, as well as between exposed vegetation (sea asparagus and green algae) and exposed eelgrass.
Incompatibilities of the automatable processing steps (Tafkaa, LSU and SAM) made automated mapping less accurate than supervised mapping, but suggestions are made toward improvement.
The value-added classification of eelgrass LAI and epiphyte type produced poor results in all cases except one; epiphyte presence / absence could be delineated with 87% accuracy.
Before applying the findings of this study, one must consider the spatial scale of the intended management goal and select imagery with suitable spatial resolution. Tidal variations, as well as seasonal variability in water conditions and eelgrass phenology must also be considered as they may affect classification accuracies.
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Baker, Kirralee Grace. "The direct implications of warming on the phenotype and underlying functional traits of marine phytoplankton." Thesis, 2016. http://hdl.handle.net/10453/90058.
Full textAbstract:
University of Technology Sydney. Faculty of Science.Marine phytoplankton mediate oceanic biogeochemical cycling by linking cellular metabolism with many elemental fluxes including C, N, P and Si. These elemental transformations are physiologically regulated processes that are influenced by phytoplankton phenotypes that change over different spatial and temporal scales. It is expected ocean warming (increasing sea surface temperatures; SST) will alter these patterns because temperature is the primary environmental control governing metabolism and growth in many phytoplankton groups. Whilst research on the effects of warming SST on biogeographical range shifts is advancing, it remains unknown how phytoplankton mediated biogeochemical transformations may be altered. Focusing on patterns in species functional traits (FTs), this thesis applied trait-based approaches in laboratory and field studies to explore how biogeochemically-related FTs vary over environmental gradients. I quantified the thermal performance curves (TPCs) of FTs in representative species from two laboratory-cultured phytoplankton functional types to understand trade-offs associated with thermal acclimation and adaptation. To assess whether these laboratory-based patterns of FT trade-offs and expression were consistent in the field; I replicated a similar TPC experiment with a natural phytoplankton community. Finally, to understand how multiple environmental gradients interact to influence phytoplankton FT expression, I tracked a diatom-specific FT over northern Australia to spatially map the diatom phenotypes present to deduce the likely biogeochemical roles of the species in the region. This thesis demonstrates the importance of understanding the relationship between the duration of thermal exposure, FT expression and trade-offs in regulating the phytoplankton phenotype, as all of these factors differentially affect species’ growth rates (and therefore fitness and biogeography) but also the acquisition of C, N, P and Si, and therefore the marine cycling of these elements. Furthermore, ocean mapping of FTs proves insightful for understanding variability of biogeochemical transformations between different ocean regions by providing a link between cellular and community level processes.
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Silva, Thiago Sanna Freire. "Spatial and temporal variability of macrophyte growth and productivity in the Amazon floodplain." Thesis, 2009. http://hdl.handle.net/1828/1754.
Full textAbstract:
The main objective of the present thesis was to investigate the spatial and temporal variability of macrophyte growth and productivity in the Amazon floodplain, and the possible effects of this variability on the carbon budget of the floodplain.
In Chapter 3, two methods for estimating macrophyte biomass were compared in terms of accuracy and applicability to the Amazon floodplain conditions. Phenotypic variation was large enough to preclude indirect (phenometric) modelling of biomass, while direct sub-sampling was able to account for this variation. Sub-sampling also allowed reduction on the biomass sampling effort, presenting the best trade-off between accuracy and coverage for macrophyte biomass measurements in the Amazon floodplain.
In Chapter 4, annual net primary production (NPP) of macrophytes was estimated for a large lake on the eastern Amazon floodplain, and the uncertainty associated with these measures was assessed, offering a comparison of previous estimates of macrophyte productivity in the Amazon region. Annual net primary production was estimated at 2400 – 3500 g m-2 yr-1, with above water production between 650 – 1100 g m-2 yr-1, and below water production between 1700 and 2600 g m-2 yr-1. Echinochloa polystachya (Poaceae) and Paspalum fasciculatum (Poaceae) were the most productive species, followed by Paspalum repens (Poaceae), Hymenachne amplexicaulis (Poaceae), and Oryza perennis (Poaceae). The four main sources of uncertainty in the estimates were macrophyte taxa, location, sampling design, and lack of measurements of dead material loss.
Chapter 5 presented a new object oriented method for combining radar and optical image time series to characterize seasonal evolution of macrophyte cover for an eastern Amazon floodplain lake. Macrophyte cover varied between 104 and 198 km2 (10% and 20% of total floodplain area, respectively) and exhibited significant changes both seasonally and inter-annually. Two distinct growth strategies were observed: short-lived communities that thrived during low water periods and year-long communities able to survive flooding year-round. Although the majority of the macrophyte carbon fixation derived from the latter, about 17% of macrophyte NPP was attributed to the short-lived communities, which depend directly on the flood levels for a given year. The increased frequency of droughts predicted for the Amazon system could potentially result in an increase on the macrophyte-derived carbon input to the Amazon floodplain.
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Lockett, Daniel Edwin IV. "A Bayesian approach to habitat suitability prediction." Thesis, 2012. http://hdl.handle.net/1957/28788.
Full textAbstract:
For the west coast of North America, from northern California to southern
Washington, a habitat suitability prediction framework was developed to
support wave energy device siting. Concern that wave energy devices may
impact the seafloor and benthos has renewed research interest in the
distribution of marine benthic invertebrates and factors influencing their
distribution. A Bayesian belief network approach was employed for learning
species-habitat associations for Rhabdus rectius, a tusk-shaped marine
infaunal Mollusk. Environmental variables describing surficial geology and
water depth were found to be most influential to the distribution of R. rectius.
Water property variables, such as temperature and salinity, were less
influential as distribution predictors. Species-habitat associations were used to
predict habitat suitability probabilities for R. rectius, which were then mapped
over an area of interest along the south-central Oregon coast. Habitat
suitability prediction models tested well against data withheld for crossvalidation
supporting our conclusion that Bayesian learning extracts useful
information available in very small, incomplete data sets and identifies which
variables drive habitat suitability for R. rectius. Additionally, Bayesian belief
networks are easily updated with new information, quantitative or qualitative,
which provides a flexible mechanism for multiple scenario analyses. The
prediction framework presented here is a practical tool informing marine
spatial planning assessment through visualization of habitat suitability.Graduation date: 2012