Dissertations / Theses: 'Ocean currents California Current'

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Tisch, Timothy Daniel. "Seasonal variability of the geostrophic velocity and water mass structure off Point Sur, California." Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241374.

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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, September 1990.
Thesis Advisor(s): Ramp, Steven R. ; Collins, Curtis A. "September 1990." Description based on title screen as viewed on December 21, 2009. DTIC Identifier(s): California Current. Author(s) subject terms: California Current, California Undercurrent, Spiciness Anomaly, Geostrophic Velocity, Water Mass Characteristics. Includes bibliographical references (p. 142-146). Also available in print.

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O'Malley, Colleen M. "The fall transition off Central California in 2002." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FOMalley.pdf.

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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Curtis A. Collins, Mary L. Batteen. Includes bibliographical references (p. 79-80). Also available online.

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Holt, Robert D. "Rip current spacing in relation to wave energetics and directional spreading." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FHolt.pdf.

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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Edward B. Thornton, Timothy Stanton. Includes bibliographical references (p. 59-62). Also available online.

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Legaard, Kasey. "Temporal Variability of Satellite-Derived Chlorophyll and Sea Suface Temperature in the California Current." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/LegaardK2004.pdf.

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Aguilar, Morales Juan. "Subtidal circulation over the upper slope to the west of Monterey Bay, California /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FAguilar.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2003.
Thesis advisor(s): Curtis A. Collins, Reginaldo Durazo. Includes bibliographical references (p. 105-108). Also available online.

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Spence, Luke J. "On the calculation of particle trajectories from sea surface current measurements and their use in satellite sea surface products off the Central California Coast." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FSpence.pdf.

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Thesis (M.S. in Applied Mathematics)--Naval Postgraduate School, December 2007.
Thesis Advisor(s): Giraldo, Francis ; Paduan, Jeffrey. "December 2007." Description based on title screen as viewed on January 18, 2008. Includes bibliographical references (p. 69). Also available in print.

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Konstantinidis, Simon. "C-vector derived three dimensional circulations in Farallones National Marine Sanctuary." Thesis, Monterey, Calif. : Naval Postgraduate School, 1992. http://catalog.hathitrust.org/api/volumes/oclc/52801700.html.

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Morales, Juan Aguilar. "Subtidal circulation over the upper slope to the west of Monterey Bay, California." Thesis, Monterey, California. Naval Postgraduate School, 2003. http://hdl.handle.net/10945/876.

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Moored current meters were used to describe currents over the continental slope off Monterey Bay, California, from March 1998 to March 2003. The water depth at this location was 1800 m and current observations included of 16-88 m, 210- 290 m, 305 m and 1200 m although measurements at 16-88 m were not continuous. Poleward currents dominated the flow between 24 and 305 m. At 305 m the mean flow was 3.9 cm/s toward 334Ê». Surprisingly, at 1200 m the mean flow reversed and was 0.8 cm/s toward 169Ê». The principal axis for the flow at 305 m (1200 m) was 349Ê» (350Ê»), the semi-major axis was 9.4 cm/s (5.8 cm/s) and the semi-minor axis 3.4 (2.0 cm/s). The direction of the principal axis and the mean flow at 1200 m was aligned with the bathymetry to the east of the mooring site. The seasonal cycle at 305 m was dominated by an acceleration of the poleward flow from a minimum near zero on April 15 to maximum, 25 cm/s on July 15. This flow resulted in an increase of temperature at 305 m of 1.2Ê»C due to geostrophic adjustment and a corresponding 10 cm increase in sea level due to steric effects. The acceleration of alongshore flow was out of phase with the alongshore pressure gradient which was greatest in mid- April. At 1200 m, the temperature increase (0.2Ê»C) only lasted from April 15 to June 1 after which equatorward flow increased and temperature decreased. Mesoscale variability dominated the velocity measurements with maximum variance at about 60- day periods. At 305 m, the eddy kinetic energy was greatest (smallest) in October (December), 40 cm2/s2 (4 cm2/s2) while at 1200 m the maximum (minimum) occurred in July (February), 5 cm2/s2 (0.5 cm2/s2). Poleward events were stronger at 305 m while equatorward events were stronger at 1200 m. The three first empirical orthogonal functions explained 90% of the temporal variability of the horizontal currents. The first, second, and third Z-scores represented flow along the principal axis, undercurrent vs. Davidson current, and upwelling modes, respectively. While the seasonal patterns for the first two modes agreed with seasonal variability described above, the seasonal variability of the upwelling mode (6% of the variance) indicated that the waters between 16 and 88 m flowed onshore during the spring and summer upwelling period.
Commander, Mexican Navy

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Feldmeier, Joel W. "Climatic variations of the California current system : application of smart climatology to the coastal ocean /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FFeldmeier.pdf.

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Thesis (M.S. in Meterology and Physical Oceanography)--Naval Postgraduate School, September 2005.
Thesis Advisor(s): Tom Murphree, Robin T. Tokmakian. Includes bibliographical references (p. 137-143). Also available online.

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Buckley, Keith Allen. "Measurements of ocean currents across the continental margin off Pt. Sur, California, in January 1990." Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA246313.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Collins, C. A. Second Reader: Garfield, Newell. "December 1990." Description based on title screen as viewed on April 01, 2010. DTIC Descriptor(s): Velocity, density, ocean currents, water, edges, acoustic waves, inshore areas, surfaces, profiles, California, acoustic equipment, geophysics, hydrographic surveying, doppler effect, east(direction), dropsondes, anomalies DTIC Identifier(s): Ocean currents, *ocean circulation, *oceanographic data, hydrographic surveying, water flow, mass flow, geostrophic currents, AVHRR(advanced very high resolution radiometers), theses, coastal regions, Davidson inshore current, high resolution, radiometers, meteorological satellites, pacific ocean, acoustic measurements, seasonal variations. Author(s) subject terms: Davidson inshore current, California current, California undercurrent, Pt. Sur transection Includes bibliographical references (p. 74-77). Also available in print.

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Robson, Alan J. "Circulation of the California undercurrent near Monterey in May 1989." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237235.

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Thesis (M.S.in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Collins, C. A. Second Reader: Schwing, F. "June 1990." Description based on title screen as viewed on October 21, 2009. DTIC identifier(s): Ocean currents, undercurrents (ocean currents), ocean circulation, ocean bottom topography, velocity, oceanographic data, California current, California undercurrent, North Pacific Ocean, spring season, submarine canyons, theses. Includes bibliographical references (p. 67). Also available in print.

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Taylor, Kelly E. "An investigation of diurnal variability in wind and ocean currents off Huntington Beach, California." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FTaylor.pdf.

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Thesis (M.S. in Meteorology and Oceanography)--Naval Postgraduate School, March 2003.
Thesis advisor(s): Leslie K. Rosenfeld, Carlyle H. Wash. Includes bibliographical references (p. 85-86). Also available online.

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Chumbinho, Rogřio Paulo Antunes. "Kinematics and dynamics of a cyclonic eddy off Pt. Arena, California /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA298587.

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Dissertation (Ph. D. in Physical Oceanography) Naval Postgraduate School, December 1994.
"December 1994." Dissertation supervisor(s): R.L. Haney. Includes bibliographical references (p. 75-79). Also available online.

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McWilliams, Brandon K. "Cuspate shoreline morphology." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FMcWilliams.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2005.
Thesis Advisor(s): Edward Thornton, Timothy Stanton. Includes bibliographical references (p. 53-54). Also available online.

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Negron, Anthony J. "Measurements of ocean currents across the continental margin off Point Sur, California, in March 1989." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/39879.

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Mean currents and density were measured off Point Sur, California in March 1989 using Pegasus and CTD instruments. Velocity, temperature, salinity, and density fields are examined to discern the structure of the California and Davidson currents. Velocities measured by Pegasus are compared to flow fields derived from geostrophy. The Davidson Current flows poleward at the surface in its winter configuration despite northerly winds and coastal upwelling which normally drive the flow subsurface in the summer months.

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Buckley, Keith A. "Measurements of Ocean Currents Across the Continental Margin off Pt. Sur, California, during January 1990." Thesis, Monterey, California: Naval Postgraduate School, 1990. http://hdl.handle.net/10945/43858.

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During the week of 17 to 24 of January, 1990, the R/V Pt. Sur conducted a hydrographic and current survey in the vicinity of Pt. Sur, CA. The ship collected data along a transection across the continental margin which began 2.5 km offshore and extended along parallel 360 20' N. At 1230 W, the transection turned towards the southwest and extended out to a point some 220 km offshore. Data were collected using CTD, PEGASUS (acoustic dropsonde), and ADCP (Acoustic Doppler Current Profiler) instruments.

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Hays, Kevin Austin Samuel. "A water mass analysis of the 1991-1992 El Niño signal in the Farallon Islands Region." Monterey, Calif. : Naval Postgraduate School, 1993. http://catalog.hathitrust.org/api/volumes/oclc/52789316.html.

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Powell, Jesse Russell. "Ocean fronts in the Southern California Current System and their role in structuring zooplankton distributions, diel vertical migration, and size composition." Thesis, University of California, San Diego, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3566029.

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Ocean fronts are dynamic gradients that divide waters with differing hydrographic properties. Fronts also play important ecological roles in structuring plankton distributions, modulating primary and secondary production, and delineating predator foraging areas. Here, I utilize autonomous “ Spray” ocean gliders to describe the spatial and seasonal distribution of deep-water fronts and their impact on the plankton within the Southern California Current System (SCCS).

To test the suitability of the Spray’s 750 kHz acoustic doppler profilers (ADP) for mapping zooplankton distributions, I first present results from a seatruthing study in which I mounted an ADP on a Mocness plankton net. I show that the relative mean volume backscatter (rMVBS) measured by the ADP is correlated with the summed zooplankton cross-sectional area (a proxy for biomass). I also find that the relationship between rMVBS and zooplankton biomass is strongest for zooplankters with an estimated spherical diameter greater than 1.6 mm. Observed rMVBS was best explained by euphausiid and copepod biomass.

From Spray cross-shore sections between October, 2006 and December, 2011, I identified 154 distinct surface layer density fronts. The strongest and most numerous fronts occurred in spring, and were located closer to the coast, whereas summer and fall fronts were found further offshore. Fronts were weakest and least numerous in winter. Across all seasons, fronts structured plankton distributions. Horizontal gradients in physical variables (e.g., surface density, temperature, and salinity) co-varied with horizontal gradients in MVBS and Chl-a fluorescence, and the magnitude of biological gradients was higher at frontal areas compared with non-frontal areas. Frontal areas were also clearly associated with elevated Chl -a and zooplankton acoustic backscatter.

Fronts divided distinct plankton habitats and associated assemblages. Chlorophyll-a fluorescence maxima and euphotic zones were deeper offshore of fronts. The amplitude of diel vertical migration by zooplankton also increased offshore, in association with increased optical transparency in the upper ocean. Additionally, ADP data indicate that zooplankton assemblages change across fronts. I employ an inverse acoustic model to estimate zooplankton size spectra, inferring that larger-bodied zooplankters contributed a greater proportion to overall biomass inshore of these fronts. Vertically-stratified zooplankton samples from both inshore and offshore regions corroborated the model results.

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Conley, Keats. "Settlement Preferences of the Pacific Sea Nettle, Chrysaora fuscescens, and the Socioeconomic Impacts of Jellyfish on Fishers in the Northern California Current." Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13232.

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Few data are available on distribution, abundance, and ecology of scyphozoans in the Northern California Current (NCC). This thesis is divided into four chapters, each of which contributes to our understanding of a different stage of the scyphozoan life history. The first study describes the settlement preferences of Chrysaora fuscescens planulae in the laboratory. Planulae were found to respond to the interaction of substrate and orientation. Artificial substrates were identified as viable habitat for C. fuscescens. In the second chapter, a population of scyphistomae in Charleston, Oregon were identified to species-level using DNA barcoding techniques. The third and fourth chapters focus on the medusa stage of the life history. Using surveys mailed to fishers in the Pacific Region, this study provides baseline data on the types and magnitudes of economic damages caused by jellyfish on different fisheries and helps assess fishers' perceptions of jellyfish population trends in the NCC. This thesis includes previously unpublished co-authored material.

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Sheen, Katy Louise. "Seismic oceanography : imaging the antarctic circumpolar current." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609132.

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Dzwonkowski, Brian. "Surface current analysis of shelf water in the central Mid-Atlantic Bight." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 179 p, 2009. http://proquest.umi.com/pqdweb?did=1697328621&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Woods, John E. "Rip current/cuspate shoreline interactions in Southern Monterey Bay." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FWoods.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2005.
Thesis Advisor(s):Edward Thornton, Timothy Stanton. Includes bibliographical references (p.41-42). Also available online.

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Mitchell, Douglas A. "Upper current structure and variability in the southwestern Japan/East Sea /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3112121.

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Corry, R. A. "Modelling the seasonal variation of the Florida current." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:644edc47-15b5-491f-a2a3-a2c25c864791.

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The linear response of a two layer ocean model to a periodic wind stress curl in the presence of bottom topography has been investigated. For periods much less than the time taken for the wind generated baroclinic Rossby waves to pass over the topography (i.e. 'short' periods), the ocean response is primarily that for a homogeneous ocean and thus strongly modified by topography. For periods much longer than this time (i.e. 'long' periods), the Rossby waves compensate for the effect of topography and the non-topographic Sverdrup balance holds. For the Atlantic at 25°N, the long period limit is of the order of years to decades, so at annual period the non-topographic Sverdrup balance is not applicable. Variations in transport can be forced by a wind stress over varying topography, and by the passage of a coastal baroclinic Kelvin wave over varying topography. The relative importance of the above dynamical considerations for the Florida Current can only be determined from a model calculation involving realistic winds, topography and geography. Such a model calculation has been done with observed Bunker wind stress over a two layer ocean. The predicted variation has a Summer maximum and a Fall minimum, in agreement with the measurements of Niiler and Richardson [1973] and more recent STACS data. The one layer model has been forced by monthly means of ATOLL wind stress for the years 1981-1984. The predicted variation was found not to be in agreement with concurrent STACS measurements. A comparison was made between the Bunker winds and the ATOLL winds via various diagnostics. It was found that the meridional component of the wind, which is crucial to the overall Bunker Summer maximum, is of much reduced importance for the ATOLL winds. This could account for the lack of predicted Summer maxima.

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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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Beal, Lisa M. "Observations of the velocity structure of the Agulhas Current." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242717.

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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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Agarwal, Arpit. "Time-averaged model for longshore current and sediment transport in the surf and swash zones." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 4.62 Mb , 106 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/1428092.

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Mohd, Akhir Mohd Fadzil. "Physical processes along the southern continental shelf and slope of Western Australia." University of Western Australia. School of Environmental Systems Engineering, 2010. http://theses.library.uwa.edu.au/adt-WU2010.0118.

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The circulation along the south coast of Western Australia was examined using field data and numerical modelling. Physical processes in this region, particularly along the continental shelf and slope regions, were poorly understood due to a paucity of field measurements. Data were collected during a research cruise on RV Southern Surveyor (04/2006) during April 2006 consisting of 18 CTD transects from Twilight Cove (126oE) to Cape Leeuwin (115oE) and was augmented by shipborne ADCP data. The field data set provided a detailed understanding of three major current systems: Leeuwin Current (LC), Leeuwin Undercurrent (LU) and Flinders Current (FC). The LC along the south coast exhibits different characteristics when compared to that along the west coast. The LC flows into the colder and lower salinity subantarctic environment of the south coast. This is evident in a strong geopotential gradient off the south-west corner of Australia (Cape Leeuwin) resulting in rapid acceleration of the LC as it reaches a maximum velocity in this region. Numerical modelling studies, using the Regional Ocean Modelling System (ROMS) indicated that wind stress is an important component of the dynamics in this region. This was identified when comparing summer and winter conditions when the winds act in opposite directions, from north-westerly to southeasterly respectively. Along the shelf break and slope, the Flinders Current (FC) interacts with LC. As the dominant current, the FC serves both as a surface and as an undercurrent, transporting sub Antarctic mode water (SAMW). This interconnection the FC and LU can be seen clearly from the salinity, temperature and velocities within the depth range 200-700m postulating a connection between subsurface waters off Tasmania (origin of the Flinders Current) and the tropical Indian Ocean through the Flinders and Leeuwin Undercurrents.

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Sapp, Brian Keith. "Observations of Laboratory Rip Currents." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10453.

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Laboratory experiments of rip current systems are performed in a wave basin with a bar and rip channel geometry at the Ocean Engineering Laboratory at the University of Delaware. The experiments include both in situ water level and velocity measurements and optical visualization of the flow field under a variety of normal-incident wave conditions. Digital video is used to record surface drifters moving through a rip current system. A method is presented that tracks these digitally-recorded drifters into long Lagrangian sequences. The laboratory measurements capture both an Eulerian and Lagrangian description of the rip current system. Time-averaged rip current properties are calculated and analyzed using both in situ and video measurements. From the video, Lagrangian velocities are computed with forward differencing of the low-pass filtered drifter tracks. Wave properties are also estimated using the orbital drifter motions and linear (Airy) wave theory. The effects of various wave conditions on the time-averaged rip current systems are investigated to show that wave height is a critical parameter. Measurements of circulation cells are obtained by spatially averaging the drifter track velocity measurements into a polar grid ranging from 0.25 m to 3.25 m from the center of the cell. Circulation cell features, such as the center of circulation and cell width, are calculated to characterize their response to various wave conditions. Spectral analyses are used to characterize the rip current pulsations in the experimental measurements. Three frequencies are found to be energetic in several of the experiments in the low frequency band: the wave group frequency, a lower frequency, and the interaction of the wave group and lower frequencies. Some experiments have significant energy at each of the three peaks, where others have only one or none. The lower frequency motions have also been found in the video measurements and attributed to rip meandering. Possible causes for the low-frequency pulsations, including wave basin seiching, circulation cell instabilities, and wave-current interaction, are discussed. This thesis adds to previous rip current studies by providing a spatially-large and time-varying perspective of rip current systems as a whole.

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Stahr, Frederick R. "Transport and bottom boundary layer observations of the North Atlantic deep western boundary current at the Blake Outer Ridge /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/10998.

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Winkel, David Patrick. "Influences of mean shear in Florida current on turbulent production by internal waves /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11024.

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Hopkins, Alicia A. "Sensitivity of bottom topography on the dynamics and sound speed structure in the Northern Canary Current System." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FHopkins.pdf.

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Thesis (M.S. in Meterology and Physical Oceanography)--Naval Postgraduate School, December 2006.
Thesis Advisor(s): Mary L. Batteen. "December 2006." Includes bibliographical references (p. 101-105). Also available in print.

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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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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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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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Hickey, Kenneth J. "Ocean surface current estimation using a long-range, single-station, high-frequency ground wave radar." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0008/MQ42394.pdf.

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Ward, Nikole S. "Investigation of Near-Bottom Current Characteristics Along an Open-Ocean Coast." UNF Digital Commons, 2018. https://digitalcommons.unf.edu/etd/827.

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Near-bottom current data was collected over a period of 8 years at the U.S. Army Corps of Engineers Field Research Facility in Duck, North Carolina. This data set consisted of currents measured up to three elevations above the bottom at deployment depths of 5 meters, 8 meters and 13 meters, as well as continuous real-time wind and wave data collected at the pier. The data was collated, quality checked and analyzed to define a climatology of near bottom currents along the study area using current moments. This data set had previously never been available for analysis due to the large amount of effort required to take old computer files and subject them to rigorous processing and quality control. The analyses conducted in this thesis represent the first ever attempt to analyze this type of data on this scale. An initial monthly investigation was conducted at the 8-meter site to determine driving forces of mean currents, and a more in depth seasonal investigation was subsequently completed to quantify the relationships between the cross-shore currents and different forcing mechanisms. Once seasonal trends were established relating mean current to incident wave height, wave steepness and wind speed, an examination of some significant historical events within the study was completed to help link cross-shore current behavior to storm events. Three separate nor’easter events and three significant hurricanes (Bonnie, Dennis and Floyd) were found to produce significant cross-shore currents at the study site. Similar to previous nearshore studies, it was found that the occurrence of onshore winds and wave heights greater than about 1.5 meters produce near-bottom mean currents moving in the offshore direction. Alternatively, when winds are blowing in the offshore direction, waves are still propagating onshore, but mean near-bottom currents tend to be directed in the onshore direction. The importance of vertical current structure within the water column was apparent, even though the instruments’ measurement elevations were all located within the bottom boundary layer. In contrast to the assumption of zero cross-shore velocity at near-coast sites implicit in two-dimensional depth averaged models used in most coastal engineering studies today, it was found that cross-shore near-bottom currents are rarely ever zero. Depth-averaged models inherently assume that currents move as a single block of water throughout the water column. The physical impacts of this misrepresentation of nearshore currents become very significant in predictions of many coastal phenomena, such as storm surge, sediment transport and wave conditions at the coast. When wave heights exceed 2 meters, mean currents tend to be between 0.2-0.5 meters per second in both the onshore and offshore direction, in the opposite direction of the primary forcing at the surface. In some instances, wave heights are low with strong mean currents while wind speeds are high, indicating the driving force in this situation is wind speed. However, there are cases where wave heights are large and mean current values are relatively low, which requires further investigation. Future work will include investigating phenomena that are related to higher-order odd moments of the current statistics, since they are expected to play a critical role in improved understanding of the physics within the nearshore and are very much needed for predictions of coastal evolution under future sea level rise and potential climate change.

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Enriquez, Andres. "An investigation of surface current patterns related to upwelling in Monterey Bay, using high frequency radar /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FEnriquez.pdf.

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40

Enriquez, Andres E. "An investigation of surface current patterns related to upwelling in Monterey Bay, using high frequency radar." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1595.

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Approved for public release; distribution is unlimited
High Frequency (HF) radar backscatter instruments are under development and testing in the marine science and defense science communities for their abilities to remotely sense surface parameters in the coastal ocean over large areas. In the Navy context, the systems provide real-time mapping of ocean surface currents and waves critical to characterization and forecasting of the battlespace environment. In this study, HF radar, aircraft and satellite information were used to investigate and describe surface current in Monterey Bay, California, for a period of ten months, from June 01st, 2003 to March 31st, 2004. A network of five CODAR-type HF radar instruments measured hourly surface currents over the bay. The measurements were averaged over one-hour intervals and total surface velocities were mapped on a grid in the Monterey Bay. From the M1 Buoy located in the middle of the bay, an uninterrupted time series of wind intensity and direction was obtained for the whole period. Major upwelling events were observed during the period of June 14 to June 27, July 4 to July 19, August 8 to August 18 and other upwelling events were observed until late October. These periods of upwelling favorable winds are common during summer with durations of 10 to 20 days. Often they are interrupted by periods of relaxation state of just a few days as the winds veer to the northwest or northeast. Cyclonic circulation cells are developed on shore during upwelling conditions and an anticyclonic circulation in the middle of the bay is observed when the wind shifts to the southwest producing a strong flow out of the bay close to the coastline off Point PioÌ¨s. Downwelling conditions are much common less than upwelling, with occurrences during winter and early fall storms with events lasting between two to five days. When the wind blows to the northeast with an intensity of 4 m/s or more for more than 12 hours, a well developed anticyclonic gyre forms in the middle of the bay. This is associated with a strong current, 35 to 40 cm/s, which flushes out in the southern part of the bay close to the coast off Point PioÌ¨s. This flow reverses when the winds veer to the southwest and enter into the Bay with less intensity.
First Lieutenant, Chilean Navy

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41

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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42

Phillips, Robyn L. "A fine resolution model of the Leeuwin Current System off western and southern Australia." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FPhillips.pdf.

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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, September 2002.
Thesis advisor(s): Mary L. Batteen, Curtis A. Collins. Includes bibliographical references (p. 85-88). Also available online.

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43

Keenlyside, Noel S. 1974. "Improved modelling of zonal currents and SST in the tropical Pacific." Monash University, Dept. of Mathematics and Statistics, 2001. http://arrow.monash.edu.au/hdl/1959.1/9072.

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44

Louw, Gavin Shaun. "Monitoring the dynamics of the Agulhas Current System off Port Edward, Kwazulu-Natal." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/2032.

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Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Oceanography in the Faculty of Applied Sciences at the Cape Peninsula University of Technology
In order to validate remote sensing products and to provide data for model assimilation, a real-time monitoring line consisting of three moorings was deployed across the Agulhas Current off Port Edward, South Africa. This deployment formed part of a Technology and Human Resource for Industry Programme (THRIP) funded initiative to develop a real-time mooring system capable of measuring ocean parameters in the Agulhas Current during 2011. The slope and offshore moorings displayed a distinct stratified regime within the Agulhas Current, a northeastward flowing Agulhas Undercurrent and the southwestward flowing Agulhas Current. Three major reversal events, with northeastward currents occurred on 23 July, 02 September and on 11 October 2011. All current reversals caused a decrease in current velocity. The Agulhas Undercurrent was a persistent feature and average velocities between the line of moorings ranged between 13.38 cm/s and 15.52 cm/s. The results obtained from the mooring systems were consistent in terms of velocity, direction and hydrographic properties of the Agulhas Current as described in previous literature. The low directional variability in the surface layers at the offshore mooring and dominant southwestward flow, except during reversal events indicate the strong influence of the Agulhas Current in this region. The inshore mooring showed less occurrences of the Agulhas Undercurrent if northward flow in the bottom layers was to be considered as signs of the Agulhas Undercurrent. General current characteristics as well as the characterisation of the mesoscale features affecting the coast off Port Edward was accomplished through the use of the in situ moorings. All current reversals encountered were associated with the process of vortex shedding from the Natal Bight. These events may be related to the shedding of the Durban Cyclonic Eddy from its origin in the Natal Bight. Data from the offshore mooring suggested that for monitoring Agulhas Current core dynamics, it was ideally placed as highest surface velocities were measured by this mooring system. The slope mooring recorded highest velocities within the Agulhas Undercurrent and was thus ideally placed to measure the Agulhas Undercurrent’s core. Shelf dynamics were under the influence of the Agulhas Current and northerly current reversals and were aptly recorded by the inshore mooring which was placed on the continental shelf, close to the shelf break.

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45

Boehme, Lars. "The frontal system of the Antarctic Circumpolar Current : marine mammals as ocean explorers." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/687.

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46

Zhang, Yanwu. "Current velocity profiling from an autonomous underwater vehicle with the application of Kalman filtering." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/69202.

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Thesis (S.M. in Oceanographic Engineering)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution); and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (leaves 74-78).
The thesis presents data processing schemes for extracting Earth-referenced current velocity from relative current velocity measurement made by an Acoustic Doppler Current Profiler (ADCP) borne by an Autonomous Underwater Vehicle (AUV). Compared with conventional approaches, current profiling from an AUV platform has advantages including three-dimensional mobility, rapid response, high-level intelligent control, independence from ship motion and weather constraint, and shallow water operation. First, an acausal postprocessing scheme is presented for estimating the AUV's own velocity and removing it from the relative velocity measurement to obtain the true current velocity. Then, a causal scheme for estimating the Earth-referenced current velocity is presented. The causal algorithm is based on an Extended Kalman Filter (EKF) that utilizes the hydrodynamics connecting current velocity to vehicle's motion. In both methods, the raw ADCP measurement is corrected to achieve more accurate current velocity estimate. Field data from the Haro Strait Tidal Front Experiment are processed by both methods. Current velocity estimation results reveal horizontal and vertical velocity structure of the tidal mixing process, and are also consistent with the vehicle's deviated trajectory. The capability of the AUV-borne current profiling system is thus demonstrated.
by Yanwu Zhang.
S.M.in Oceanographic Engineering

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47

Peña-Molino, Beatriz. "Variability in the North Atlantic Deep Western Boundary Current : upstream causes and downstream effects as observed at Line W." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62495.

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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 165-174).
The variability in the DWBC, its connection to the forcing in the northern North Atlantic and interaction with the Gulf Stream were explored from a combination of remote sensing and in-situ measurements in the western North Atlantic. Using satellite altimetry and Sea Surface Temperature (SST) we found evidence of the relation between changes in the Gulf Stream path and the variability in the temperature and velocity fields in the Slope Water. This relation was such that southward shifts of the main axis of the Gulf Stream were preceded by cold temperature anomalies and intensification of the southwestward flow. The analysis of 5.5 years of moored CTD and horizontal velocity data in the DWBC at 69 0W recorded during the period 2002-2008, showed that the variability along the DWBC is linked to changes in the dense water formation regions. The evolution of potential vorticity (PV) at the mooring site, characterized by a transition from deep to upper Labrador Sea Water (LSW), was similar to that observed in the Labrador Sea 6 to 9 years earlier, and imply spreading rates for the LSW that varied over time from 1.5 to 2.5cm/s. The time dependence of the spreading rates was in good agreement with changes in the strength of the DWBC at the mooring site. The evolution of the DWBC transport was explored in more detail from a 5- element moored array, also at 69'W. The results, for the period of 2004-2008, were consistent with the single mooring analysis. The variability measured from the array showed that upper, intermediate and deep water mass layers expand and contract at each other's expense, leading to alternating positive and negative PV anomalies at the upper-LSW, deep-LSW and Overflow Water (OW). Larger DWBC transports were associated with enhanced presence of recently ventilated upper-LSW and OW, rather than deep-LSW. The relative contribution of the different water masses to the observed circulation was investigated by inverting individual PV anomalies isolated from the observations. We found that changes in the depth-integrated circulation were mostly driven by changes in the OW.
by Beatriz Peña-Molino.
Ph.D.

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48

Hanson, Christine Elizabeth. "Oceanographic forcing of phytoplankton dynamics in the coastal eastern Indian Ocean." University of Western Australia. Centre for Water Research, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0033.

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[Truncated abstract] This work was the first large-scale biological oceanographic study to be undertaken in the coastal eastern Indian Ocean adjacent to Western Australia, and covered both northwest (Exmouth Peninsula to the Abrolhos Islands) and southwest (Cape Naturaliste to Cape Leeuwin) regions. The study area was dominated by the Leeuwin Current (LC), an anomalous eastern boundary current that transports tropical water poleward and prevents deep nutrients from reaching the surface by creating large-scale downwelling. Indeed, LC and offshore waters were consistently associated with low nitrate concentrations and low phytoplankton biomass and production (< 200 mg C m-2 d-1). However, the physical forcing of the LC was offset, during the summer months, by upwelling associated with wind-driven inshore countercurrents (Ningaloo and Capes Currents), which provided a mechanism to access high nutrient concentrations normally confined to the base of the LC. ... Limited seasonal investigations off the Capes region of southwestern Australia showed that the winter production scenario can be very different than summer conditions, with strong Leeuwin Current flow that meanders onto the continental shelf and entrains seasonally nutrient-enriched shelf waters. However, production in the LC was still low (≤450 mg C m-2 d-1) due to light limitation resulting from both increased light attenuation and reduced surface irradiance characteristic of the winter months. This investigation provides fundamental knowledge on physical-biological coupling off Western Australia, with implications for fisheries management in view of seasonal and inter-annual variability in the strength of both the Leeuwin Current and inshore countercurrents.

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49

Combes, Vincent. "Upwelling and cross-shelf transport dynamics along the Pacific Eastern Boundary." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34814.

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The upwelling and cross-shelf transport dynamics along the Pacific Eastern Boundary is explored using a high resolution ocean model for the last 60 years. Three ocean circulations have been modeled. From North to South, we investigate the dynamics of the Gulf of Alaska (GOA), the California Current System (CCS) and the Humboldt Current System (HCS, also known as the Peru-Chile Current System). The statistics of coastal waters transport are computed using a model passive tracer, which is continuously released at the coast. By looking at the passive tracer concentration distribution, we find that the Pacific Decadal Oscillation modulates the coastal variability of the GOA, the North Pacific Gyre Oscillation controls the upwelling of the CCS, while the El-Niño Southern Oscillation affects the upwelling of Peru and Chile mainly through coastally trapped Kelvin waves. Results also emphasize the key role of the mesoscale eddies in the offshore transport of coastal waters masses. The passive tracer experiments, performed in this study in the GOA, CCS, and HCS, therefore could provide a dynamical framework to understand the dynamics of the upwelling/downwelling and offshore transport of nutrient rich coastal water and to interpret how it responds to atmospheric forcing. This also could reinforce our interpretation (and therefore predictions) in the changes in vertical and offshore advection of other important biogeochemical quantities, essential in understanding ecosystem variability.

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50

Sutherland, David A. (David Alan). "The East Greenland Coastal Current : its structure, variability, and large-scale impact." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43156.

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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008.
Includes bibliographical references (p. 155-161).
The subtidal circulation of the southeast Greenland shelf is described using a set of high resolution hydrographic and velocity transects occupied in summer 2004. The main feature present is the East Greenland Coastal Current (EGCC), a low-salinity, high velocity jet with a wedge-shaped hydrographic structure characteristic of other surface buoyancy-driven currents. The EGCC was observed along the entire Greenland shelf south of Denmark Strait, while the transect north of the strait showed only a weak shelf flow. This observation, combined with evidence from chemical tracer measurements that imply the EGCC contains a significant Pacific Water signal, suggests that the EGCC is an inner branch of the polar-origin East Greenland Current (EGC). A set of idealized laboratory experiments on the interaction of a buoyant current with a submarine canyon also supported this hypothesis, showing that for the observed range of oceanic parameters, a buoyant current such as the EGC could exhibit both flow across the canyon mouth or into the canyon itself, setting the stage for EGCC formation. Repeat sections occupied at Cape Farewell between 1997 and 2004 show that the along shelf wind stress can also have a strong influence on the structure and strength of the EGCC and EGC on timescales of 2-3 days. Accounting for the wind-induced effects, the volume transport of the combined EGC/EGCC system is found to be roughly constant (-2 Sv) over the study domain, from 68*N to Cape Farewell near 60°N. The corresponding freshwater transport increases by roughly 60% over this distance (59 to 96 mSv, referenced to a salinity of 34.8). This trend is explained by constructing a simple freshwater budget of the EGCC/EGC system that accounts for melt water runoff, melting sea-ice and icebergs, and net precipitation minus evaporation.
(cont.) Variability on inter annual timescales is examined by calculating the Pacific Water content in the EGC/EGCC from 1984-2004 in the vicinity of Denmark Strait. The PW content is found to correlate significantly with the Arctic Oscillation index, lagged by 9 years, suggesting that the Arctic Ocean circulation patterns bring varying amounts of Pacific Water to the North Atlantic via the EGC/EGCC.
by David A. Sutherland.
Ph.D.

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