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1
Patoux, Jérôme. "Frontal wave development over the Southern Ocean /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/10067.
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Konstantinou, Nikolaos. "Ocean mixed layer response to gap wind scenarios." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FKonstantinou.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, December 2006.Thesis Advisor(s): Qing Wang, Roland W. Garwood. "December 2006." Includes bibliographical references (p. 61-62). Also available in print.
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Zeng, Lixin. "The verification and application of satellite scatterometer winds /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10077.
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Fei, Chen-Yang. "Vortex-induced vibrations of structural members in natural winds." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36006.
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Kennedy, Richard A. "A numerical study of the forcing mechanisms of the Leeuwin current system /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FKennedy.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2002.Thesis advisor(s): Mary L. Batteen, Curtis A. Collins. Includes bibliographical references (p. 93-96). Also available online.
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Byars, Beverly J. "Variation of the drag coefficient with wind and wave state." Thesis, Monterey, Calif. : Naval Postgraduate School, 1985. http://catalog.hathitrust.org/api/volumes/oclc/52763691.html.
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Duhaut, Thomas H. A. "Wind-driven circulation : impact of a surface velocity dependent wind stress." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101117.
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The use of an ocean surface velocity dependent wind stress is examined in the context of a 3-layer double-gyre quasigeostrophic wind-driven ocean circulation model. The new wind stress formulation results in a large reduction of the power input by the wind into the oceanic circulation. This wind stress is proportional to a quadratic function of Ua--u o, where Ua is the wind at 10m above the ocean surface and uo is the ocean surface current. Because the winds are typically faster than the ocean currents, the impact of the ocean surface velocity on the wind stress itself is relatively small. However, the power input is found to be greatly reduced with the new formulation. This is shown by simple scaling argument and numerical simulations in a square basin. Our results suggest that the wind power input may be as much as 35% smaller than is typically assumed.The ocean current signature is clearly visible in the scatterometer-derived wind stress fields. We argue that because the actual ocean velocity differs from the modeled ocean velocities, care must be taken in directly applying scatterometer-derived wind stress products to the ocean circulation models. This is not to say that the scatterometer-derived wind stress is not useful. Clearly the great spatial and temporal coverage make these data sets invaluable. Our point is that it is better to separate the atmospheric and oceanic contribution to the stresses.
Finally, the new wind stress decreases the sensitivity of the solution to the (poorly known) bottom friction coefficient. The dependence of the circulation strength on different values of bottom friction is examined under the standard and the new wind stress forcing for two topographic configurations. A flat bottom and a meridional ridge case are studied. In the flat bottom case, the new wind stress leads to a significant reduction of the sensitivity to the bottom friction parameter, implying that inertial runaway occurs for smaller values of bottom friction coefficient. The ridge case also gives similar results. In the case of the ridge and the new wind stress formulation, no real inertial runaway regime has been found over the range of parameters explored.
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Kunkee, David Bryan. "Polarimetric millimeter-wave thermal emission from anisotropic water surfaces : application to remote sensing of ocean surface wind direction." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/14689.
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Wu, Zhaohua. "Thermally driven surface winds in the tropics /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/10075.
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Cheon, Woo Geunn. "Impact of the Southern ocean winds on sea-ice - ocean interaction and its associated global ocean circulation in a warming world." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3029.
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Harden, Benjamin. "Barrier winds off Southeast Greenland and their impact on the ocean." Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/39451/.
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Li, Huimin. "Global observations of ocean surface winds and waves using spaceborne synthetic aperture radar measurements." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2019. http://www.theses.fr/2019IMTA0138/document.
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Les radars à synthèse d'ouverture (SAR) spatioportés ont fait la preuve de leur valeur inestimable dans l'observation des vents et des vagues océaniques mondiaux. Les images SAR acquises par plusieurs capteurs sont utilisées, notamment Sentinel-1 (S-1), Envisat/ASAR, Gaofen-3 et Radarsat-2. Cette thèse passe en revue les paramètres SAR couramment utilisés dans la première partie. Une série d'étapes d'étalonnage sont nécessaires pour obtenir un NRCS approprié et une évaluation du NRCS est effectuée pour le mode d'onde S-1 (WV). Il s'avère que WV est mal calibré et est donc recalibré pour obtenir un NRCS précis. Il a été démontré que la coupure de l'azimut est complémentaire du NRCS et peut expliquer l'impact de l'état de la mer sur l'extraction du vent. D'après les produits SAR entièrement polarimétriques disponibles, la coupure de l'azimut varie considérablement en fonction des polarisations. La transformation actuelle de la cartographie SAR est suffisante pour interpréter la coupure azimutale copolarisée, mais pas pour la polarisation croisée. Compte tenu des limites de l'imagerie SAR, un nouveau paramètre est proposé et défini en fonction du spectre croisé de l'image SAR, appelé MACS. La partie imaginaire de MACS est une quantité signée par rapport à la direction du vent. Compte tenu de cette dépendance, on s'attend à ce qu'un algorithme indépendant de récupération du vent en bénéficie. L'ampleur du MACS peut aider à estimer la fonction de modulation de la cartographie SAR. De plus, la MACS donne également des résultats prometteurs en ce qui concerne les études globales sur les vagues. Les signatures globales du MACS à différentes longueurs d'onde sont bien représentatives de la distribution spatiale et saisonnière des vents. Les MACS des vagues longues montrent des valeurs plus élevées sur les trajectoires des tempêtes alors que les vagues plus courtes sont principalement dans les vents des trader. Ces résultats devraient aider à évaluer les résultats du modèle et compléter les études ultérieures sur le climat spectral global des vaguesSpaceborne synthetic aperture radar (SAR) has been demonstrated invaluable in observing the global ocean winds and waves. SAR images acquired by multiple sensors are employed, including Sentinel-1(S-1), Envisat/ASAR, Gaofen-3 and Radarsat-2. This thesis reviews the commonly used SAR parameters (NRCS and azimuth cutoff) in the first part. A series of calibration steps are required to obtain a proper NRCS and assessment of NRCS is carried out for S-1wave mode (WV). It turns out that WV is poorly calibrated and is thus re-calibrated to obtain accurate NRCS. Azimuth cut off is demonstrated to be complementary to NRCS and can account for the sea state impact on the wind retrieval. Based on the available fully polarimetric SAR products, azimuth cut off is found to vary greatly with polarizations. The present SAR mapping transformation is sufficient to interpret the co-polarized azimuth cut off, while not for the cross-polarization. With the limitations of SAR imaging in mind, a new parameter is proposed and defined based on the SAR image cross-spectra, termed as MACS. The imaginary part of MACS is found to be a signed quantity relative to the wind direction. Given this dependence, an independent wind retrieval algorithm is expected to benefit. The magnitude of MACS is able to aid for estimate of modulation function of SAR mapping. In addition, MACS also gives promising results regarding the global wave studies. The global signatures of MACS at various wave lengths are well representative of the winds distributions, spatially and seasonally. MACS of long waves shows greater values over the storm tracks while the shorter waves are mostly within the trader winds. These results are expected to help evaluate the model outputs and complement further studies of the global wave spectral climate. Data continuity in the coming 10 years shall extend the study towards longer duration
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Meuleners, Michael Joseph. "A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2007.0134.
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Piepmeier, Jeffrey R. "Remote sensing of ocean wind vectors by passive microwave polarimetry." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15027.
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Lee, Hyong Sun. "The Coastal Ocean Response to Strong Offshore Winds in the Gulfs of Tehuantepec and Papagayo." NSUWorks, 1990. http://nsuworks.nova.edu/occ_stuetd/79.
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Four ocean models are used to investigate the response of the coastal ocean to strong offshore winds: a linear 11/2-layer model, a linear 21/2-layer model, a nonlinear 11/2-layer model and a nonlinear 21/2-layer model. The nonlinear models include thermodynamics and entrainment, the latter allowing cool lower-layer water to move into the upper layer. The models are forced by wind stress fields similar in structure to the intense winter-time, mountain-pass jets (~20 dyne/cm2) that appear in the Gulfs of Tehuantepec and Papagayo and blow directly offshore for periods of 3 - 10 days. Analytic and numerical solutions are arranged in a hierarchy of increasing dynamical complexity in order to illustrate the important physical processes. They compare favorably with observations in several ways, including the large sea-level drop at the coast and the fast westward propagation speeds of anticyclones.
While the wind strengthens there is an ageostrophic current (not Ekman drift) that is directed offshore. This offshore drift forces coastal upwelling, thereby lowering the local sea level and sea surface temperature (SST). Although the drop in sea level at the coast can be large and rapid, none of this signal propagates poleward as an upwelling-favorable coastally trapped wave. While the wind weakens the ageostrophic current is directed onshore, and consequently the coastal ocean readjusts toward its initial state. Throughout the wind event, cyclonic and anticyclonic gyres spin up offshore on either side of the jet axis due to Ekman pumping. Entrainment cools SST offshore on and to the right (looking onshore) of the jet axis, and virtually eliminates the cyclonic gyre. The advection terms intensify the anticyclonic gyre and give it a more circular shape. After a wind event, the anticyclonic gyre propagates westward due to β. In all the 11/2-layer solutions, its propagation speed is less than observed values. In the 21/2-layer solutions, however, the Tehuantepec gyre moves westward and southward at a speed of 7.5 km/day and Papagayo gyre propagates westward at 12.8 km/day, both close to observed speeds.
The coastal sea-level drop is enhanced by several factors: horizontal mixing, advection of the upper-layer thickness field h, enhanced forcing, coastal geometry, and the existence of a second active layer in the 21/2-layer model. Horizontal mixing enhances the sea-level drop because the coastal boundary layer is actually narrower with mixing; consequently, the interface below the upper-layer must rise farther to balance the volume of water that is displaced offshore. Advection of h intensifies upwelling by carrying regions of shallow h offshore. The forcing τ/h is enhanced near the coast where h is thin. When the coastal geometry includes a bay, the wind has an alongshore component that intensifies upwelling at the apex of the bay. Finally, in analytic solutions to the 21/2-layer model the presence of two baroclinic modes increases the sea-level drop to some degree; in numerical solutions the maximum sea-level drop also increases because it is not as severely limited as it is in the 11/2-layer model. Of these factors the strengthened forcing τ/h has by far the largest effect on the magnitude of the drop, and when all of them are included the resulting maximum drop is -30.0 cm, close to observed values.
To investigate the processes that influence the propagation speeds of anticyclones, several test wind-forced calculations as well as additional numerical experiments with isolated eddies were carried out. Solutions to dynamically simpler versions of the 11/2-layer model show that the speed is increased both by β-induced self-advection and by larger h at the center of the gyre, both factors measuring the strength of the gyre circulation. Solutions to the 21/2-layer model indicate that the lower-layer flow field advects the gyres westward and southward, significantly increasing their propagation speed. Solutions with isolated eddies confirm that self-advection enhances the propagation speed of 11/2-layer anticyclones, and indicate that it is advection by a wind-forced background circulation that increases the speed of 21/2-layer anticyclones.
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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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Schillinger, Douglas J. "Wind speed estimates and precipitation detection using ambient sound in the ocean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ55540.pdf.
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ADISSI, FLÁVIA. "THE CONTRIBUTION OF OCEAN DRIFTERS AND NUMERICAL SIMULATIONS OF OCEAN CURRENTS AND WINDS IN SUPPORT OF THE TERRITORIAL PLANNING: THE CASE OF GUANABARA BAY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27618@1.
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Este trabalho aborda a questão da movimentação e acúmulo do lixo flutuante
na Baía de Guanabara e contextualiza a problemática da poluição da Baía e seu
entorno a partir de diversos temas inter-relacionados, como: o uso dos derivadores
e a sua analogia com o lixo flutuante; a existência de projetos que têm ajudado no
rastreamento do lixo flutuante na Baía a partir do mapeamento de correntes
superficiais e ventos; o saneamento da bacia hidrográfica da Baía, a qualidade da
água de seus afluentes e a análise da população que reside no seu entorno; o
entendimento de uma visão mais humanista e ecológica no redesenho das cidades
e também programas internacionais de revitalização de corpos d água degradados.
Dentro deste contexto, são feitas reflexões e análises integradas a partir de uma
modelagem da probabilidade de transporte de resíduos da Baía e da paisagem
encontrada em seu entorno, através da utilização de produtos cartográficos. Tais
análises consideram os dados levantados nos quatro mapas que são apresentados,
de forma a prover uma visão mais ampla e integrada do espelho d água e também
do entorno da Baía. O objetivo deste trabalho foi entender como o espaço territorial
e a ocupação urbana do entorno da Baía podem impactar a poluição do espelho
d água da Baía e por ela serem impactados de forma a contribuir com programas de
despoluição. Foi feito então um recorte em quatro regiões e realizada uma análise
integrada para cada, de forma a prover um melhor entendimento a partir da
exemplificação. A análise integrada proporciona uma visão mais abrangente da
questão da poluição, auxiliando os gestores dos programas de despoluição a
encontrarem relevantes informações para priorizar as ações a serem tomadas.This work approaches the issue of the movement and accumulation of floating litter in the Guanabara Bay, in Rio de Janeiro, Brazil. It contextualizes the problem of the pollution in the Bay and surroundings, and it does so from several different interrelated issues, such as the use of ocean drifters and their analogy with the floating litter; the existence of projects that have been helping in the tracking of the floating litter in the Bay from the mapping of the surface currents and the winds; the sanitation efforts in the hydrographic basin of the Bay; the quality of the water in the rivers that debouch into the Bay and a better understanding of the population that live in the area; the necessity of a more humanistic and ecological view in the planning of those cities; and also international programs to revitalize degraded water bodies. One of the objectives of this dissertation is to understand how the territorial space and the urban occupation of the Bay s surroundings can impact the pollution in the Bay and be impacted by that pollution. So the entire region was divided in four areas and an integrated analysis was made for each area so that a better understanding could be provided by exemplification. Such integrated analysis provides a more comprehensive view of the pollution problem and helps the depollution program officers to find relevant information and better prioritize actions. The Guanabara Bay plays a strategic role not only around the towns and cities that are part of its hydrographic basins, but in the whole state of Rio de Janeiro and also the entire country. It is one of the most important marine ecosystems from the social, economic and environmental points of view. It is located in the Rio de Janeiro city metropolitan area, with the Brazilian coast s largest population concentration (about 10 million people, or 80 percent of the state s population). A national security area, the Bay shelters two naval bases, one navy shipyard, the Rio de Janeiro Port (the second largest in the country, with more than 2 thousand ship moorings annually), two airports (Antonio Carlos Jobim, and Santos Dumont), and other shipyards and marinas. The Guanabara Bay is also way for innumerous cargo and passenger ferryboats, fishing boats, and other boats for leisure and tourism. The water in the Bay is also used for water sports and aquaculture (fish farming). (KJERFVE, 1997; BERGAMO, 2006 apud CARVALHO, 2011).
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EL-Nimri, Salem. "AN IMPROVED MICROWAVE RADIATIVE TRANSFER MODEL FOR OCEAN EMISSIVITY AT HURRICANE FORCE SURFACE WIND SPEED." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2523.
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An electromagnetic model for predicting the microwave blackbody emission from the ocean surface under the forcing of strong surface winds in hurricanes is being developed. This ocean emissivity model will be incorporated into a larger radiative transfer model used to infer ocean surface wind speed and rain rate in hurricanes from remotely sensed radiometric brightness temperature. The model development is based on measurements obtained with the Stepped Frequency Microwave Radiometer (SFMR), which routinely flys on the National Oceanic and Atmospheric Administration's hurricane hunter aircraft. This thesis presents the methods used in the wind speed model development and validation results for wind speeds up to 70 m/sec. The ocean emissivity model relates changes in measured C-band radiometric brightness temperatures to physical changes in the ocean surface. These surface modifications are the result of the drag of surface winds that roughen the sea surface, produce waves, and create white caps and foam from the breaking waves. SFMR brightness temperature measurements from hurricane flights and independent measurements of surface wind speed are used to define empirical relationships between microwave brightness temperature and surface wind speed. The wind speed model employs statistical regression techniques to develop a physics-based ocean emissivity model dependent on geophysical parameters, such as wind speed and sea surface temperature, and observational parameters, such as electromagnetic frequency, electromagnetic polarization, and incidence angle.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
20
Meuleners, Michael Joseph. "A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system." University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0134.
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[Truncated abstract] The study of eastern ocean boundary currents has been principally restricted to the Pacific and Atlantic ocean regions. The traditional view of the circulation near eastern ocean boundaries is that upwelling-favourable winds force surface waters offshore, leading to upwelling of cold, nutrient-rich subsurface water at the coast, the formation and offshore advection of a coastal front, and the generation of alongshore currents, generally having an equatorward surface flow and a poleward undercurrent. The eastern ocean boundary system of the southern Indian Ocean, off the west coast of Australia, is unique compared with these regions because a warm, poleward surface flow, known as the Leeuwin Current, dominates the dynamics over the continental shelf. Satellite imagery has shown the Leeuwin Current consists of a complex system of meanders, jet-like streams, and eddies, and has a seasonal and interannual variability. The oceanic circulation of the region between Carnarvon (latitude 25°S) and Jurien Bay (latitude 31°S) was examined using observational and remotely sensed data in conjunction with a detailed numerical modelling study. The model was validated using in situ ADCP and CTD data, and the horizontal eddy viscosity parameterization was tested against field observations. ... The resulting offshore meander grew laterally, shallowed, and closed to form an anticlockwise eddy to the original clockwise eddy’s south, forming a characteristic LC eddy pair (dipole). The model demonstrated the LC and Leeuwin Undercurrent (LUC) coupling played an important role in the onset of eddies at both sites. When an energy diagnostic scheme was used, the dominant instability process linked to the anticlockwise eddy’s development at site 1 was a mixed mode barotropic and baroclinic instability. The baroclinic instability’s source was the available potential energy stored within the mean lateral density gradient. The LC’s meandering southerly flow interacting with the LUC’s northerly subsurface flow generated the horizontal shear that sourced the barotropic instability. The dominant instability process at site 2 was baroclinic in origin. Possible links between the eddy field dynamics and the shelfslope region’s alongshore topographic variability were considered. The results of a suite of five model runs, differing only in the specification of bottom topography, were contrasted to investigate the effects. Except for the expected alongshore variability, delay in the onset of instabilities, varying growth rates, and some differences in the dominant wavebands’ mesoscale patterns, the overall impression was the response was similar.
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Wargula, Anna (Anna Elizabeth). "Wave-, wind-, and tide-driven circulation at a well-mixed ocean inlet." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111741.
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Thesis: Ph. D. in Mechanical and Oceanographic Engineering, Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-104).
The effects of waves, wind, and bathymetry on tidal and subtidal hydrodynamics at unstratified, shallow New River Inlet, NC, are evaluated using field observations and numerical simulations. Tidal flows are ebb-dominated (-1.5 to 0.6 m/s, positive is inland) inside the main (2 to 5 m deep) channel on the (1 to 2 m deep) ebb shoal, owing to inflow and outflow asymmetry at the inlet mouth. Ebb-dominance of the flows is reduced during large waves (> 1 m) owing to breaking-induced onshore momentum flux. Shoaling and breaking of large waves cause depression (setdown, offshore of the ebb shoal) and super-elevation (setup, on the shoal and in the inlet) of the mean water levels, resulting in changes to the cross-shoal pressure gradient, which can weaken onshore flows. At a 90-degree bend 800-m inland of the inlet mouth, centrifugal acceleration owing to curvature drives two-layered cross-channel flows (0.1 to 0.2 m/s) with surface flows going away from and bottom flows going toward the bend. The depth-averaged dynamics are tidally asymmetric. Subtidal cross-channel flows are correlated (r² > 0.5) with cross-channel wind speed, suggesting that winds are enhancing and degrading the local-curvature induced two-layer flow, and driving three-layer flow.
by Anna Wargula.
Ph. D. in Mechanical and Oceanographic Engineering
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Alsweiss, Suleiman Odeh. "An improved ocean vector winds retrieval approach using C- and Ku-band scatterometer and multi-frequency microwave radiometer measurements." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4832.
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The analysis of these satellite data provided confidence in the capability of the simulation to generate realistic active/passive measurements at the top of the atmosphere. Results are very encouraging, and they show that the new algorithm can retrieve accurate ocean surface wind speeds in realistic hurricane conditions using the rain corrected Ku-band scatterometer measurements. They demonstrate the potential to improve wind measurements in extreme wind events for future wind scatterometry missions such as the proposed GCOM-W2.; This dissertation will specifically address the issue of improving the quality of satellite scatterometer retrieved ocean surface vector winds (OVW), especially in the presence of strong rain associated with tropical cyclones. A novel active/passive OVW retrieval algorithm is developed that corrects Ku-band scatterometer measurements for rain effects and then uses them to retrieve accurate OVW. The rain correction procedure makes use of independent information available from collocated multi-frequency passive microwave observations provided by a companion sensor and also from simultaneous C-band scatterometer measurements. The synergy of these active and passive measurements enables improved correction for rain effects, which enhances the utility of Ku-band scatterometer measurements in extreme wind events. The OVW retrieval algorithm is based on the next generation instrument conceptual design for future US scatterometers, i.e. the Dual Frequency Scatterometer (DFS) developed by NASA's Jet Propulsion Laboratory. Under this dissertation research, an end-to-end computer simulation was developed to evaluate the performance of this active/passive technique for retrieving hurricane force winds in the presence of intense rain. High-resolution hurricane wind and precipitation fields were simulated for several scenes of Hurricane Isabel in 2003 using the Weather Research and Forecasting (WRF) Model. Using these numerical weather model environmental fields, active/passive measurements were simulated for instruments proposed for the Global Change Observation Mission- Water Cycle (GCOM-W2) satellite series planned by the Japanese Aerospace Exploration Agency. Further, the quality of the simulation was evaluated using actual hurricane measurements from the Advanced Microwave Scanning Radiometer and SeaWinds scatterometer onboard the Advanced Earth Observing Satellite-II (ADEOS-II).ID: 029810202; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 108-111).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
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Luke, Jeremy Blaine. "High Resolution Wind Retrieval for SeaWinds on QuikSCAT." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd220.pdf.
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Fenlason, Joel W. "Accuracy of tropical cyclone induced winds using TYDET at Kadena AB." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FFenlason.pdf.
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Fletcher, Andrew S. "An Implementation of Field-Wise Wind Retrieval for Seawinds on QuikSCAT." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/69.
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Field-wise wind estimation (also known as model-based wind estimation) is a sophisticated technique to derive wind estimates from radar backscatter measurements. In contrast to the more traditional method known as point-wise wind retrieval, field-wise techniques estimate wind field model parameters. In this way, neighboring wind vectors are jointly estimated, ensuring consistency. This work presents and implementation for field-wise wind retrieval for the SeaWinds scatterometer on the QuikSCAT satellite.
Due to its sophistication, field-wise wind retrieval adds computational complexity and intensity. The tradeoffs necessary for practical implementations are examined and quantified. The Levenberg-Marquardt algorithm for minimizing the field-wise objective function is presented. As the objective function has several near-global local minima, several wind fields represent ambiguous wind field estimates. A deterministic method is proposed to ensure sufficient ambiguities are obtained. An improved method for selecting between ambiguous wind field estimates is also proposed.
With a large set of Sea-Winds measurements and estimates available, the σ° measurement statistics are examined. The traditional noise model is evaluated for accuracy. A data-driven parameterization is proposed and shown to effectively estimate measurement bias and variance. The parameterized measurement model is used to generate Cramer-Rao bounds on estimator performance. Using the Cramer-Rao bound, field-wise and point-wise performances are compared.
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Walton, M. Patrick. "Concepts for Rapid-refresh, Global Ocean Surface Wind Measurement Evaluated Using Full-System Parametric Extrema Modeling." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9157.
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Satellite wind vector data is integral to atmospheric models and forecasts. Currently, the limited refresh rate of global wind vector measurement systems makes it difficult to observe diurnal variation of mesoscale processes. Using advancements in the underlying subsystem technologies, new satellite wind scatterometers may be possible that increase temporal resolution, among other performance metrics. I propose a method for parametrically modeling the extreme performance range of a complex system. I use this method to develop a model of the space of possible satellite wind scatterometer designs. I validate the model using point designs of heritage scatterometers. Finally, I present two example concepts for constellations of cooperative satellite wind scatterometers capable of measuring global ocean surface vector winds every hour for the same total cost as a single heritage scatterometer.
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Spencer, Michael W. "A Methodology for the Design of Spaceborne Pencil-Beam Scatterometer Systems." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/76.
Full textAbstract:
Spaceborne scatterometer instruments are important tools for the remote sensing of the Earth's environment. In addition to the primary goal of measuring ocean winds, data from scatterometers have proven useful in the study of a variety of land and cryopshere processes as well. Several satellites carrying scatterometers have flown in the last two decades. These previous systems have been "fan-beam" scatterometers, where multiple antennas placed in fixed positions are used. The fan-beam scatterometer approach, however, has disadvantages which limit its utility for future missions. An alternate approach, the conically-scanning "pencil-beam" scatterometer technique, alleviates many of the problems encountered with earlier systems and provides additional measurement capability. Due to these advantages, the pencil-beam approach has been selected by NASA as the basis for future scatterometer missions. Whereas the fan-beam approach is mature and well understood, there is need for a fundamental study of the unique aspects of the pencil-beam technique.
In this dissertation, a comprehensive treatment of the design issues associated with pencil-beam scatterometers is presented. A new methodology is established for evaluating and optimizing the performance of conically-scanning radar systems. Employing this methodology, key results are developed and used in the design of the SeaWinds instrument - NASA's first pencil-beam scatterometer. Further, the theoretical framework presented in this study is used to propose new scatterometer techniques which will significantly improve the spatial resolution and measurement accuracy of future instruments.
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Blodgett, Jeffrey Richard. "Analysis, Validation, and Improvement of High-Resolution Wind Estimates from the Advanced Scatterometer (ASCAT)." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5614.
Full textAbstract:
The standard L2B ocean wind product from the Advanced Scatterometer (ASCAT) is retrieved as a 25 km product on a 12.5 km grid. Ultra-high resolution (UHR) processing allows ASCAT wind retrieval on a high-resolution 1.25 km grid. Ideally, such a high-resolution sample grid provides wind information down to a 2.5 km scale, allowing better analysis of winds with high spatial variability such as those in near-coastal regions and storms. Though the wind field is sampled on a finer grid, the actual data resolution needs to be validated. This thesis provides an analysis and validation of ASCAT UHR wind estimates in order to determine the improvement in resolution compared to the L2B product. This is done using analysis tools such as statistics, the power spectrum, and derivative fields, and through comparison to other high-resolution data such as synthetic aperture radar (SAR). The improvement of UHR wind retrieval is also explored by reducing ambiguity selection errors and correcting for contamination of wind vectors near land. Results confirm that ASCAT UHR winds contain high-resolution information that is not present in the L2B product. The resolution improvement is difficult to quantify due to a lack of truth data. Nevertheless, there is evidence to suggest that the resolution is improved by at least a factor of three to 10 km, and perhaps down to 3 or 4 km. It is found through comparison of UHR and SAR winds that (1) both products have common fine-scale features, (2) their comparative statistics are similar to that of L2B and SAR, suggesting that the high resolution content agrees just as well as the low resolution content because the comparison is performed at a finer scale (3) both products have derivative fields that match well, (4) the UHR product benefits from high-resolution direction information, and (5) the UHR product matches better the expected spectral properties of ocean winds. For the UHR processing improvement methods, the model-based improvement of UHR ambiguity selection allows obvious ambiguity errors to be found and corrected, increases the self-consistency of the wind field, and causes the spectrum to better follow a power law at high wavenumbers. The removal of land-contamination from near-coastal wind vectors allows accurate wind retrieval much closer to land and greater visibility of high-resolution wind features near the coast.
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Halterman, Richard Ryan. "Observation and Tracking of Tropical Cyclones Using Resolution Enhanced Scatterometry." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1062.
Full textAbstract:
The QuikSCAT scatterometer provides global daily coverage of oceanic near-surface vector winds. Recently, algorithms have been developed to enhance the spatial resolution of QuikSCAT winds from 25~km to 2.5~km posting. These ultra-high resolution winds are used, in comparison with standard L2B data product winds, to observe and track tropical cyclones. Resolution enhanced winds are found to provide additional storm structure such as inner core size and structure and the presence of multiple eyewalls compared with standard resolution winds. The 2.5~km winds are also able to observe storms nearer to the shore than 25~km winds. An analysis of circulation center locatability with each resolution wind field is performed. Center fixes with enhanced resolution winds are nearer the National Hurricane Center best-track positions than are standard resolution center fixes. A data and image set of every tropical cyclone worldwide observed by Seawinds on QuikSCAT or SeaWinds on ADEOS II from 1999 through 2005 is generated and made available to the scientific community at http://scp.byu.edu.
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Spiro, Jaeger Gualtiero Victor Rudi. "Stratified and stirred : monsoon freshwater in the Bay of Bengal." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122332.
Full textAbstract:
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-121).
Submesoscale ocean dynamics and instabilities, with characteristic scales 0.1-10 kin, can play a critical role in setting the ocean's surface boundary layer thickness and associated density stratification. Submesoscale instabilities contribute to lateral stirring and tracer dispersal. These dynamics are investigated in the Bay of Bengal, motivated by the upper ocean's potentially coupled interactions with Monsoon winds and convection. The region's excess precipitation and runoff generates strong salinity gradients that typically set density fronts and stratification in the upper 50 m. Since we cannot synoptically measure currents containing fast-evolving and oscillating components across the submesoscale range, we instead analyze passive tracer distributions (spice = density-compensated temperature (T) and salinity (S) anomalies), identifying signatures of flows and testing dynamical theories.
The analysis is based on over 9000 vertical profiles of T and S measured along ~4800 km of ship tracks in the Bay of Bengal during ASIRI and MISO-BOB expeditions in 2013, 2015, and 2018. Observations in the surface mixed layer reveal ~1 km scale-selective correlation of surface T and S, with compensation reducing cross-front density gradients by ~50%. Using a process study ocean model, we show this is caused by submesoscale instabilities slumping fronts, plus surface cooling over the resultant enhanced salinity stratification, potentially thwarting the forward cascade of energy. In the stratified interior, we present a spectral analysis of horizontal spice variance statistics from wavenumber k ~0.01 cpkm to ~1 cpkm. At scales <10 km, stratified layers that are closer to the surface exhibit redder passive tracer spectra (power spectra k⁻³, gradient spectra k⁻¹) than predicted by quasi-geostrophic or frontogenetic theories.
Complimentary observations reveal spice patterns with multiple, parallel, ~10 m thin layers, crossing isopycnals with O(10⁻⁴) slopes, coherent over at least 30-80 kin, with coincident layers of stratification anomalies. Comparison with shear measurements, and a numerical process study, suggest that both submesoscale sheared eddies, and thin near-inertial waves, form such layers. Fast formation timescales and large aspect ratios suggest they enhance horizontal mixing by shear dispersion, reducing variance at ~1-10 km scales.
by Gualtiero Victor Rudi Spiro Jaeger.
Ph. D.
Ph.D. Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution)
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Zedler, Sarah E. "Strong wind forcing of the ocean." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3273808.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed October 2, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 121-127).
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Yelland, Margaret J. "Wind stress over the open ocean." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/55375/.
Full textAbstract:
An automatic inertial dissipation system was used during three cruises of the RRS Discovery in the Southern Ocean to obtain a large data set of open-ocean wind stress estimates. The wind speed varied from near-calm to 26 m/s, and the sea-air temperature differences ranged from -8 to +4°C. It is shown that, under unstable atmospheric conditions, the assumption of a balance between local production and dissipation of turbulent kinetic energy is false, and that the sign and magnitude of the imbalance, !D, depends critically on both stability, z / L , and wind speed, U10N: !D = z L 0.5 " U 10N 6.5 # $ % & ' ( z / L < 0 Application of this empirical term increased the wind stress values obtained under unstable conditions, and brought them into agreement with the data obtained under neutral conditions. The flow of air around the RRS Discovery was simulated in three dimensions using a computational fluid dynamics model. The vertical displacement and the acceleration of the air flow reaching the anemometer site were quantified. The results were used to correct the measured drag coefficient, CD10N , and wind speed estimates. The resulting mean wind stress to wind speed relationship: 1000 CD10N = 0.53 + 0.064U10N 6 !U10N ! 26 m/ s confirmed those obtained by Smith (1980) and Large and Pond (1981). Wave measurement suggested that the sea state was not, on average, fully developed for wind speeds above 12 m/s. However, contrary to findings from other studies, no persistent anomalies in the drag coefficient were detected despite the range of conditions and sea states encountered. It is shown that the wave-age dependent wind stress formulae, derived by previous authors from data obtained over shallow water, do not apply to open ocean conditions.
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Lee, Kwang Hyun. "Responses of floating wind turbines to wind and wave excitation." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33564.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.Includes bibliographical references (leaf 55).
The use of wind power has recently emerged as a promising alternative to conventional electricity generation. However, space requirements and public pressure to place unsightly wind turbines out of visual range make it desirable to move large wind farms offshore and into deeper coastal waters. A necessary step for the deployment of wind turbines into deeper waters is the development of floating platform systems. This thesis will present a general technical description of two concept designs for floating wind turbine systems, and make a preliminary evaluation of their performance in wind and waves. A new approach to computing the nonlinear wave excitation is also presented.
by Kwang Hyun Lee.
S.M.
34
Davidson, Fraser. "Wind driven circulation in Trinity and Conception Bays /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0020/NQ47495.pdf.
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Kalmikov, Alexander G. "Modeling wind forcing in phase resolving simulation of nonlinear wind waves." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/57791.
Full textAbstract:
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), 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 148-152).
Wind waves in the ocean are a product of complex interaction of turbulent air flow with gravity driven water surface. The coupling is strong and the waves are non-stationary, irregular and highly nonlinear, which restricts the ability of traditional phase averaged models to simulate their complex dynamics. We develop a novel phase resolving model for direct simulation of nonlinear broadband wind waves based on the High Order Spectral (HOS) method (Dommermuth and Yue 1987). The original HOS method, which is a nonlinear pseudo-spectral numerical technique for phase resolving simulation of free regular waves, is extended to simulation of wind forced irregular broadband wave fields. Wind forcing is modeled phenomenologically in a linearized framework of weakly interacting spectral components of the wave field. The mechanism of wind forcing is assumed to be primarily form drag acting on the surface through wave-induced distribution of normal stress. The mechanism is parameterized in terms of wave age and its magnitude is adjusted by the observed growth rates. Linear formulation of the forcing is adopted and applied directly to the nonlinear evolution equations. Development of realistic nonlinear wind wave simulation with HOS method required its extension to broadband irregular wave fields. Another challenge was application of the conservative HOS technique to the intermittent non-conservative dynamics of wind waves. These challenges encountered the fundamental limitations of the original method. Apparent deterioration of wind forced simulations and their inevitable crash raised concerns regarding the validity of the proposed modeling approach. The major question involved application of the original HOS low-pass filtering technique to account for the effect of wave breaking. It was found that growing wind waves break more frequently and violently than free waves.
(cont.) Stronger filtering was required for stabilization of wind wave simulations for duration on the time scale of observed ocean evolution. Successful simulations were produced only after significant sacrifice of resolution bandwidth. Despite the difficulties our modeling approach appears to suffice for reproduction of the essential physics of nonlinear wind waves. Phase resolving simulations are shown to capture both - the characteristic irregularity and the observed similarity that emerges from the chaotic motions. Energy growth and frequency downshift satisfy duration limited evolution parameterizations and asymptote Toba similarity law. Our simulations resolve the detailed kinematics and the nonlinear energetics of swell, windsea and their fast transition under wind forcing. We explain the difference between measurements of initial growth driven by a linear instability mechanism and the balanced nonlinear growth. The simulations validate Toba hypothesis of wind-wave nonlinear quasi-equilibrium and confirm its function as a universal bound on combined windsea and swell evolution under steady wind.
by Alexander G. Kalmikov.
S.M.
36
Whitford, Dennis James. "Wind and wave forcing of longshore currents across a barred beach." Thesis, Monterey, Calif. : Naval Postgraduate School, 1988. http://catalog.hathitrust.org/api/volumes/oclc/52803820.html.
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Kukulka, Tobias. "The effect of breaking waves on a coupled model of wind and ocean surface waves." View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3248233.
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Kiss, Andrew Elek. "Dynamics of laboratory models of the wind-driven ocean circulation." View thesis entry in Australian Digital Theses Program, 2000. http://thesis.anu.edu.au/public/adt-ANU20011018.115707/index.html.
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Scott, Nicholas Vicente. "Observations of the wind-wave spectrum and steep wave statistics in open ocean waters." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3103724.
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Horstmann, Jochen. "Measurement of ocean wind fields with synthetic aperture radar." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=965193853.
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Whitney, Claudia S. "Modeling the tropical ocean response to westerly wind forcing." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23969.
Full textAbstract:
Approved for public release; distribution is unlimitedA primitive equation ocean general circulation model, with mixed layer physics, has been developed and applied to an investigation of the equatorial ocean. The major physical problem addressed with this model is the response of the upper ocean to westerly wind events, such as those that occur during tropical cyclones and during El Nino events. In the model development phase, several configurations of the mixed layer physics, domain size, and wind stress were tested. The best overall simulations were produced when both Richardson number dependent mixing and a bulk mixed layer model were included. Small model domains were found to be especially sensitive to the prescribed lateral boundary conditions and wind stress. Smaller domains required more realistic wind stress fields in order to achieve reasonable current structures. In addition, the off-equatorial currents were particularly responsive to changes in the zonal gradient of the wind stress. The final configuration of the model produces realistic simulations of climatological threedimensional temperature and current structures in the equatorial ocean. In the model application phase, synoptically varying winds for the tropical Pacific were used to force the model. The winds came from the Navy's Operational Global Atmospheric Prediction System's (NOGAPS) daily analyses for the 1991-92 El Nino, which included several strong westerly wind events. The strong temporal and spatial variability in these winds produced complex fluctuations of the model's temperatures, currents, and internal waves, including reversals of the South Equatorial Current and equatorially trapped Kelvin waves. Model verification was performed by comparison with an observational study of in situ equatorial Pacific buoy data. This comparison showed that synoptic scale variations in the wind stress are needed to simulate the ocean's strong responses to westerly wind events.
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Klima, Kelly. "Effects of variable wind stress on ocean heat content." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45788.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008.Includes bibliographical references (p. 82-86).
Ocean heat content change (ocean heat uptake) has an important role in variability of the Earth's heat balance. The understanding of which methods and physical processes control ocean heat uptake needs improvement in order to better understand variability in the Earth's heat balance, improve the simulation of present-day climate, and improve the understanding and projection of future climate. Wind stress can play a strong role in ocean heat uptake on all timescales, and short timescale wind stress effects have not been well studied in the literature. This study for the first time examines short timescale spatial and temporal patterns of global variable wind stress datasets in a coupled atmosphere-ocean climate model. NCEP wind stress dataset was characterized for years 1978 to 2007. NCEP monthly means and monthly standard deviations are of the same magnitude, and strong wind stress events (tropical cyclones) are observed. A variety of metrics cannot reliably identify significant timescales or spatial patterns of the variable wind stress. Model behavior with and without variable wind stress is studied. This study uses the MIT IGSM, a 4°x 11 vertical level zonal atmospheric model coupled at the four hour timestep to a 20x2.50x22 vertical level ocean model with the K profile parameterization. Ocean properties in a no forcing scenario are sensitive to variable wind stress. In a weak forcing scenario (observed forcing over the last century), ocean properties are sensitive to variable wind stress, and internal modes of variability (such as an equatorial Pacific oscillation) are observed. In a global warming scenario (1% CO2 rise per year or a business as usual emissions scenario), the strong forcing overwhelms the more subtle responses due to the differences in variable wind stress forcing. Regardless of forcing, the high frequency variable wind stress (monthly or less) variable wind stresses can force a low frequency response. Hence the major source of annual variability of the MOC in this coarse resolution model is surface wind variability.
by Kelly Klima.
S.M.
43
Loveday, Benjamin. "Modelling wind-driven inter-ocean exchange in the greater Agulhas with the regional ocean modelling system." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/8805.
Full textAbstract:
Includes bibliographical references.Two Regional Ocean Modelling System configurations, AGIO and ARC112, are developed to investigate (1) the structure of the Agulhas leakage, (2) the dynamical link between the leakage and the Agulhas Current, and (3) the sensitivity of this link to changes in the regional wind field. Both configurations span the Indian Ocean and South East Atlantic Ocean (29° W - 115° E, 48.25° S - 7.5° N) at 1/4° resolution. ARC112 includes a two-way, AGRIF nested, 1/12° child domain, encapsulating the Agulhas retroflection (0° E - 40° E, 45.5° S - 29.5° S). Model evaluation shows that the basin-scale circulation patterns of the South Indian Ocean are appropriately captured. Western boundary transports match those derived from in situ hydrography, though source region fluxes exceed those observed. Both configurations exhibit inertially governed retroflections and produce Agulhas rings with eddy kinetic energy patterns consistent with those derived from altimetry. Improved topography in ARC112 yields a retroflection position and leakage value closer to observations. Dominant regional water masses are captured, but discrepancies in their distributions remain, especially in highly turbulent areas. The interannual variability of upper ocean heat content is well captured, and Indian Ocean dipole modes are appropriately expressed. Leakage is shown to be confined to the top 1500 m. Flux estimates, derived using complementary Eulerian passive tracer and Lagrangian virtual float techniques, converge where retroflection position is more accurate. Eddy flux, isolated using an Okubo-Weiss parameterisation, contributes only 1/3 to the total flux at the GoodHope line, with a 2:1 anticyclone to cyclone ratio. The remaining intra-ring flux occurs due to mixing between rings in the Cape Basin thermocline, which contains up to 50% Indian Ocean waters. Using a hybrid-criteria eddy-tracking scheme, ARC112i is shown to represent all three recently identified eddy paths, producing an accurate number of rings and cyclones with trajectories and radii that mirror observations, despite higher simulated speeds. A multi-decadal strengthening of the eddy component of Agulhas leakage is ascribed to increases in anti-cyclone speed and cyclone size. Linear changes in trade wind intensity, imposed through a series of idealised wind stress anomalies, concomitantly modulate Agulhas Current transport. The leakage flux response to changing western boundary current inertia is minimal, decreasing with higher resolution. Large changes in eddy kinetic energy are associated with small leakage anomalies, suggesting that the former is a poor leakage proxy. Initially, the leakage responds linearly to increasing westerly wind intensity, but increased mixing between the Agulhas Return Current and Antarctic Circumpolar Current reduces inter-basin flux as the latter adjusts. Consequently, it is suggested that Agulhas Current and leakage magnitude may, to a degree, vary independently, and that multi-decadal trends in the region may be a function of the wind forcing used. Equatorward shifts in the zero line of wind-stress curl drive a small leakage increase, counter to proposed palaeoceanographic mechanism where leakage is implied to reduce under these conditions.
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Rudge, Daniel, and Chen-Yang Fei. "Response of structural members to wind-induced vortex shedding." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/12836.
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Qin, Wenting. "Application of the spectral wave model SWAN in Delaware Bay." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 4.68 Mb., 130 p, 2005. http://proquest.umi.com/pqdlink?did=1037889341&Fmt=7&clientId=8331&RQT=309&VName=PQD.
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Yu, Xuri. "Dynamics of seasonal and interannual variability in the equatorial Pacific." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11065.
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Blencoe, David Guy. "Impact of high resolution wind fields on coastal ocean models." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA397471.
Full textAbstract:
Thesis (M.S. in Meteorology and Oceanography) Naval Postgraduate School, Sept. 2001.Thesis advisor: Paduan, Jeff. "September 2001." Includes bibliographical references (p. 67-69). Also available online.
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Kiss, Andrew Elek, and Andrew Kiss@anu edu au. "Dynamics of laboratory models of the wind-driven ocean circulation." The Australian National University. Research School of Earth Sciences, 2001. http://thesis.anu.edu.au./public/adt-ANU20011018.115707.
Full textAbstract:
This thesis presents a numerical exploration of the dynamics governing
rotating flow driven by a surface stress in the " sliced cylinder " model
of Pedlosky & Greenspan (1967) and Beardsley (1969), and its close
relative, the " sliced cone " model introduced by Griffiths & Veronis
(1997). The sliced cylinder model simulates the barotropic wind-driven
circulation in a circular basin with vertical sidewalls, using a depth
gradient to mimic the effects of a gradient in Coriolis parameter. In the
sliced cone the vertical sidewalls are replaced by an azimuthally uniform
slope around the perimeter of the basin to simulate a continental slope.
Since these models can be implemented in the laboratory, their dynamics
can be explored by a complementary interplay of analysis and numerical
and laboratory experiments. ¶
In this thesis a derivation is presented of a generalised
quasigeostrophic formulation which is valid for linear and moderately
nonlinear barotropic flows over large-amplitude topography on an f-plane,
yet retains the simplicity and conservation properties of the standard
quasigeostrophic vorticity equation (which is valid only for small depth
variations). This formulation is implemented in a numerical model based
on a code developed by Page (1982) and Becker & Page (1990). ¶
The accuracy of the formulation and its implementation are confirmed by
detailed comparisons with the laboratory sliced cylinder and sliced cone
results of Griffiths (Griffiths & Kiss, 1999) and Griffiths & Veronis
(1997), respectively. The numerical model is then used to provide insight
into the dynamics responsible for the observed laboratory flows. In the
linear limit the numerical model reveals shortcomings in the sliced cone
analysis by Griffiths & Veronis (1998) in the region where the slope and
interior join, and shows that the potential vorticity is dissipated in an
extended region at the bottom of the slope rather than a localised region
at the east as suggested by Griffiths & Veronis (1997, 1998). Welander's
thermal analogy (Welander, 1968) is used to explain the linear
circulation pattern, and demonstrates that the broadly distributed
potential vorticity dissipation is due to the closure of geostrophic
contours in this geometry. ¶
The numerical results also provide insight into features of the flow at
finite Rossby number. It is demonstrated that separation of the western
boundary current in the sliced cylinder is closely associated with a
" crisis " due to excessive potential vorticity dissipation in the viscous
sublayer, rather than insufficient dissipation in the outer western
boundary current as suggested by Holland & Lin (1975) and Pedlosky
(1987). The stability boundaries in both models are refined using the
numerical results, clarifying in particular the way in which the western
boundary current instability in the sliced cone disappears at large
Rossby and/or Ekman number. A flow regime is also revealed in the sliced
cylinder in which the boundary current separates without reversed flow,
consistent with the potential vorticity " crisis " mechanism. In addition
the location of the stability boundary is determined as a function of the
aspect ratio of the sliced cylinder, which demonstrates that the flow is
stabilised in narrow basins such as those used by Beardsley (1969, 1972,
1973) and Becker & Page (1990) relative to the much wider basin used by
Griffiths & Kiss (1999). ¶
Laboratory studies of the sliced cone by Griffiths & Veronis (1997)
showed that the flow became unstable only under anticyclonic forcing. It
is shown in this thesis that the contrast between flow under cyclonic and
anticyclonic forcing is due to the combined effects of the relative
vorticity and topography in determining the shape of the potential
vorticity contours. The vorticity at the bottom of the sidewall smooths
out the potential vorticity contours under cyclonic forcing, but distorts
them into highly contorted shapes under anticyclonic forcing. In
addition, the flow is dominated by inertial boundary layers under
cyclonic forcing and by standing Rossby waves under anticyclonic forcing
due to the differing flow direction relative to the direction of Rossby
wave phase propagation. The changes to the potential vorticity structure
under strong cyclonic forcing reduce the potential vorticity changes
experienced by fluid columns, and the flow approaches a steady free
inertial circulation. In contrast, the complexity of the flow structure
under anticyclonic forcing results in strong potential vorticity changes
and also leads to barotropic instability under strong forcing. ¶
The numerical results indicate that the instabilities in both models
arise through supercritical Hopf bifurcations. The two types of
instability observed by Griffiths & Veronis (1997) in the sliced cone are
shown to be related to the western boundary current instability and
" interior instability " identified by Meacham & Berloff (1997). The
western boundary current instability is trapped at the western side of
the interior because its northward phase speed exceeds that of the
fastest interior Rossby wave with the same meridional wavenumber, as
discussed by Ierley & Young (1991). ¶
Numerical experiments with different lateral boundary conditions are also
undertaken. These show that the flow in the sliced cylinder is
dramatically altered when the free-slip boundary condition is used
instead of the no-slip condition, as expected from the work of Blandford
(1971). There is no separated jet, because the flow cannot experience a
potential vorticity " crisis " with this boundary condition, so the western
boundary current overshoots and enters the interior from the east. In
contrast, the flow in the sliced cone is identical whether no-slip,
free-slip or super-slip boundary conditions are applied to the horizontal
flow at the top of the sloping sidewall, except in the immediate vicinity
of this region. This insensitivity results from the extremely strong
topographic steering near the edge of the basin due to the vanishing
depth, which demands a balance between wind forcing and Ekman pumping on
the upper slope, regardless of the lateral boundary condition. The
sensitivity to the lateral boundary condition is related to the
importance of lateral friction in the global vorticity balance. The
integrated vorticity must vanish under the no-slip condition, so in the
sliced cylinder the overall vorticity budget is dominated by lateral
viscosity and Ekman friction is negligible. Under the free-slip condition
the Ekman friction assumes a dominant role in the dissipation, leading to
a dramatic change in the flow structure. In contrast, the much larger
depth variation in the sliced cone leads to a global vorticity balance in
which Ekman friction is always dominant, regardless of the boundary
condition.
49
Walkington, Ian A. "Wind and bouyancy driven models of sub-tropical ocean gyres." Thesis, Keele University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397658.
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Miller, Michael W. (Michael William). "A spaceborne microwave radiometer design for ocean wind remote sensing." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39388.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 60-61).
by Michael W. Miller.
M.Eng.