Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 58 for “"Gyres"”.
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The importance of dissolved organic nutrients in the biogeochemistry of oligotrophic gyres
… production within two major ocean oligotrophic gyres: the Southern Indian Ocean gyre and the subtropical North Atlantic gyre. <br/>A transect across the Indian ocean at 32°S conducted in March/April 2002 was sampled for dissolved oxygen, inorganic and organic nutrients and phytoplankton pigments …
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Meridional heat transport by wind-driven gyres in the oceanic mixed layer
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989.
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Chaotic advection, mixing, and property exchange in three-dimensional ocean eddies and gyres
This work investigates how a Lagrangian perspective applies to models of two oceanographic flows: an overturning submesoscale eddy and the Western Alboran Gyre. In the first case, I focus on the importance of diffusion as compared to chaotic advection for tracers in this system. Three methods are …
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Chaotic advection, mixing, and property exchange in three-dimensional ocean eddies and gyres
This work investigates how a Lagrangian perspective applies to models of two oceanographic flows: an overturning submesoscale eddy and the Western Alboran Gyre. In the first case, I focus on the importance of diffusion as compared to chaotic advection for tracers in this system. Three methods are …
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Exchanges between hemispheres and gyres : a direct approach to the mean circulation of the equatorial Pacific
An extensive set of new high-quality hydrographic data is assembled in order to determine the mean circulation in the equatorial Pacific, and thus the pathways for cross-equatorial and cross-gyre exchange. Making up the core of the data set are two onetime transpacific zonal sections nominally at …
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Particulate organic carbon and mineral export from the North and South Atlantic gyres : the 234Th/238U disequilibrium approach.
Subtropical ocean gyres are typically characterised by low carbon export into the deep ocean. However, due to their large area, even relatively small average carbon export may be globally significant. Strong correlations observed between deep-sea organic carbon, calcite and opal suggest that …
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Mesoscale variability and mean flow interaction near the Gulf Stream as seen by satellite altimetry and numerical modelling
… eddy vorticity flux drives two counter rotating gyres on either side of the stream. The anisotropy can be important in the eddy vorticity flux, even when its departure from the isotropic case is smalL. Meridional or zonal anisotropies can drive recirculation gyres similar in strength and position …
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Mesoscale variability and mean flow interaction near the Gulf Stream as seen by satellite altimetry and numerical modelling
… eddy vorticity flux drives two counter rotating gyres on either side of the stream. The anisotropy can be important in the eddy vorticity flux, even when its departure from the isotropic case is small. Meridional or zonal anisotropies can drive recirculation gyres similar in strength and position …
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Eddies and friction : removal of vorticity from the wind-driven gyre
… promise for eddy parameterization, eddy-driven gyres rotating opposite the wind, and temporal complexity including basin resonances. I also demonstrate that multiple-gyre calculations have weaker mean circulation than single-gyres with the same viscosity and subtropical forcing. Despite …
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A study of the large scale circulation and water mass formation in the Nordic seas and Arctic Ocean
… dense overflows are the Iceland and Greenland gyres, west of the North Atlantic Current. Aside from the finding that the new circulation scheme is more likely in terms of water mass properties, currents etc., one fundamental problem with the old scheme lies with supplying a substantial …
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Triple oxygen isotopes and oxygen/argon ratio measurements to enhance coastal and open ocean production/respiration comparisons
… a latitudinal transect through the subtropical gyres in the Atlantic Ocean in October/November 2010. G and N were determined at weekly intervals between September 2009 and September 2010 at station L4. Annual N was positive (net autotrophic) at (0.88±0.24) mol m-2 a-1 O2. The triple oxygen …
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Eddy-mean flow interactions in western boundary current jets
… a localized forcing drive mean recirculation gyres through the process of nonlinear rectification; and (ii) a study of the role of eddies in the downstream evolution of a baroclinic jet subject to mixed instabilities. It also includes an observational analysis to characterize eddy-mean flow …
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Investigation of primary productivity along the Atlantic Meridional Transect (50°N to 33°S) through fast repetition rate fluorometry
… of deep chlorophyll maximum in the oligotrophic gyres, e.g. where nitrate was replete, values of Fv/Fm were relatively low at both pre-dawn and mid-day stations. This persistent low value of Fv/Fm at pre-dawn, e.g. after overnight darkness in nitrate replete conditions, leads to the proposition …
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Wind-Induced Exchange in Semi-Enclosed Basins
… transverse component of velocity described three gyres. The main gyre was clockwise (looking downwind) and occupied the entire basin cross-section, as expected from the earth's rotation and the presence of channel walls. The other two gyres were small and localized, and were linked to the lateral …
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Eddy-mean flow interactions in western boundary current jets
… a localized forcing drive mean recirculation gyres through the process of nonlinear rectification; and (ii) a study of the role of eddies in the downstream evolution of a baroclinic jet subject to mixed instabilities. It also includes an observational analysis to characterize eddy-mean flow …
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Studies of climate variability in a simple coupled model
… coupled configurations: an aquaplanet in which gyres are absent, and an aquaplanet in which a ridge extending from pole to pole supports gyres. Empirical Orthogonal Functions (EOFs) are used to explore the main features of variability exhibited by extended integrations of both configurations. In …
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Genes and structural proteins of the phage SYN5 of the marine cyanobacteria, Synechococcus
… photosynthetic cells in the large oligotrophic gyres of the open oceans, and contribute an estimated 30% to the oceanic photosynthetic budget. Cyanophages have been isolated which propagate on many strains of Synechococcus and Prochlorococcus. Cyanophages can effect community structure and …
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Meridional circulation in the tropical North Atlantic
… are characterized by cyclonic recirculation gyres. A paricularly notable result of the deep western basin analysis is the negligible net flow of middle NADW. Although the horizontal circulation patterns described in this study agree well with results from many previous studies, the meridional …
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Automated feature extraction in oceanographic visualization
… automate adaptive sampling. Vortices (eddies and gyres) and upwelling, two typical and important features of the ocean, are studied.
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Prochlorococcus genetic transformation and genomics of nitrogen metabolism
… phytoplankton in the oligotrophic, oceanic gyres where major plant nutrients such as nitrogen (N) and phosphorus (P) are at nanomolar concentrations. Nitrogen availability controls primary productivity in many of these regions. The cellular mechanisms that Prochlorococcus uses to acquire and …
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