Dissertations / Theses on the topic 'Eastern Pacific Ocean'
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Mickett, John B. "Turbulent entrainment fluxes within the eastern Pacific warm pool /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/11005.
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Prabhakar, Gouri. "Characteristics of Regional Aerosols: Southern Arizona and Eastern Pacific Ocean." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332834.
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Atmospheric aerosols impact the quality of our life in many direct and indirect ways. Inhalation of aerosols can have harmful effects on human health. Aerosols also have climatic impacts by absorbing or scattering solar radiation, or more indirectly through their interactions with clouds. Despite a better understanding of several relevant aerosol properties and processes in the past years, they remain the largest uncertainty in the estimate of global radiative forcing. The uncertainties arise because although aerosols are ubiquitous in the Earth's atmosphere they are highly variable in space, time and their physicochemical properties. This makes in-situ measurements of aerosols vital in our effort towards reducing uncertainties in the estimate of global radiative forcing due to aerosols. This study is an effort to characterize atmospheric aerosols at a regional scale, in southern Arizona and eastern Pacific Ocean, based on ground and airborne observations of aerosols. Metals and metalloids in particles with aerodynamic diameter (Dp) smaller than 2.5μm are found to be ubiquitous in southern Arizona. The major sources of the elements considered in the study are identified to be crustal dust, smelting/mining activities and fuel combustion. The spatial and temporal variability in the mass concentrations of these elements depend both on the source strength and meteorological conditions. Aircraft measurements of aerosol and cloud properties collected during various field campaigns over the eastern Pacific Ocean are used to study the sources of nitrate in stratocumulus cloud water and the relevant processes. The major sources of nitrate in cloud water in the region are emissions from ships and wildfires. Different pathways for nitrate to enter cloud water and the role of meteorology in these processes are examined. Observations of microphysical properties of ambient aerosols in ship plumes are examined. The study shows that there is an enhancement in the number concentration of giant cloud condensation nuclei (Dp>2 μm) in ship plumes relative to the unperturbed background regions over the ocean.
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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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Ceballos, Lina Isabel. "North pacific gyre oscillation synchronizes climate fluctuations in the eastern and western boundary systems." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26552.
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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009.Committee Chair: Di Lorenzo, Emanuele; Committee Member: Bracco, Annalisa; Committee Member: Webster, Peter J.. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Bowman, Katlin L. "MERCURY DISTRIBUTIONS AND CYCLING IN THE NORTH ATLANTIC AND EASTERN TROPICAL PACIFIC OCEANS." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1420818402.
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Palacz, Artur Piotr. "Control Mechanisms in Nutrient Dynamics and Biological Productivity in the Eastern Equatorial Pacific Ocean." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/PalaczA2011.pdf.
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Ferguson, Megan Caton. "Cetacean population density in the Eastern Pacific Ocean : analyzing patterns with predictive spatial models /." Online version in PDF format, 2005. http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Coastal_Marine_Mammal/Ferguson2005dissertation.pdf.
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Thesis (Ph. D.)--University of California, San Diego, 2005.Vita. Includes bibliographical references. Also available online in PDF format via the National Marine Fisheries Service Coastal Marine Mammal Program (CMMP) home page.
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Curtis, Jan. "A case study of explosive cyclogenesis in the eastern Pacific Ocean 14-17 December 1987." Thesis, Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26907.
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Approved for Public release; distribution is unlimitedAn explosive cyclogenesis event that occurred in the eastern Pacific Ocean on 14-17 December 1987 is investigated using the National Meteorological Center (NMC) final analyses and Geostationary Operational Environmental Satellite (GOES) digital imagery. Forecasts for this cyclone by the Navy Operational Global Atmospheric Prediction System (NOGAPS 3.0) and NMC Nested Grid Mesh (NGM) forecasts initialized at 12 UTC 14 December are also evaluated. Quasi-Lagrangian budgets of mass and vorticity are computed to determine the factors responsible for the development of this intense cyclone. The initial surface development occurs within a strong baroclinic zone southeast of a significant short-wave trough aloft. Rapid intensification is accompanied by large cyclonic vorticity advection in the upper troposphere as the surface cyclone moves under the divergent quadrant of a 250mb jet streak. A key element in this development is the superposition between the pre-existing surface low and upper level short-wave trough in a favorable weak static stability environment. These observations support earlier studies that upper level forcing acts as a critical catalyst in initiating eastern ocean explosive development.
http://archive.org/details/casestudyofexplo00curt
Lieutenant Commander, United States Navy
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Brookshire, Brian Neville Jr. "Character of the diatom assemblage spanning a depositional transition in the Eastern Equatorial Pacific Ocean at 6.6 Ma." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1626.
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Approximately 6.6 million years ago in the Eastern Equatorial Pacific a large increase in biogenic mass accumulation rates (MARs) occurred. This increased level of biogenic mass accumulation persisted until about 4.4 Ma at which time levels returned to those similar to before the transition at 6.6 Ma. The exact nature of the change that facilitated this transition in biogenic MARs, however, was not understood. Here we present the results of a study which characterizes the diatom assemblage spanning the depositional transition at 6.6 Ma from sediments taken from ODP Hole 850B. A close inspection of lithology reveals a clear change in lithology from a diatom nannofossil ooze to a nannofossil diatom ooze at 6.6 Ma. This transition is immediately followed by the occurrence of laminated diatom ooze (LDO). Diatom absolute abundance data reveals three levels of productivity associated with pre-transitional, post-transitional, and LDO formational sediments. An increase in the absolute abundance of Thalassionema nitzschioides was the major contributor to the formation of post-transitional, and LDO sediments. The known ecological preferences of this species indicate an overall increase in nutrient availability followed by sporadic changes in nutrient availability. These changes in nutrient availability could be associated with the establishment, or increase in strength, of an upwelling cell and/or the increase in nutrients made available via upwelling due to a shoaling of the thermocline.
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Tonin, Hemerson E., and hemer tonin@flinders edu au. "Atmospheric freshwater sources for eastern Pacific surface salinity." Flinders University. Chemistry, Physics and Earth Sciences, 2006. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20061031.080144.
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The remarkable salinity difference between the upper Pacific and Atlantic Oceans is often explained through net export of water vapour across Central America. To investigate this mechanism a study of salinity signals in the Equatorial Pacific Ocean current system was made looking at responses to fresh water input from two sources (local versus remote - Atlantic Ocean) as well as a combination of the two. Statistical analyses (Empirical Orthogonal Functions, Single Value Decomposition and Wavelet analysis) were used to split the main sources of the atmospheric freshwater input into local and remote contributions and to quantify both contributions. The remote source was assumed to have been transported over Central America from the Atlantic Ocean as an atmospheric freshwater flux, whereas the local source originated in the Pacific Ocean itself. The analysis suggests that 74% of the total variance in precipitation over the tropical eastern Pacific is due to water vapour transport from the Atlantic. It also demonstrates strong influence of ENSO events, with maximum correlation at a two months time lag. During La Ni�a periods the precipitation variance is more closely related to water vapour transport across Central America (the remote source), while during El Ni�o periods it is more closely related to the water vapour transport by Southerly winds along the west coast of South America (the local source). The current and temperature fields provided by the Modular Ocean Model (version 2) were used to study the changes in the salinity field when freshwater was added to or removed from the model. ECMWF ERA-40 data taken from the ECMWF data server was used to determine the atmospheric flux of freshwater at the ocean surface, in the form of evaporation minus precipitation (E-P). The Mixed Layer Depth (MLD) computed from temperature and salinity fields determines to what depth the salinity's dilution/concentration takes place for every grid point. Each MLD was calculated from the results of the previous time step, and the water column was considered well mixed from the surface to this depth. The statistical relationships were used to reconstruct the precipitation over the tropical eastern Pacific. A numerical ocean model, which uses currents and temperature from a global ocean model and is forced by precipitation, was used to study the ocean's response to either the remote or the local source acting in isolation. Through time lag correlation analysis of the sea surface salinity anomalies produced by the variation in the reconstructed precipitation fields, it is found that the anomaly signals of salinity propagate westward along the Equator at a rate of approximately 0.25 m.s-1 (6.1 degrees per month).
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Karnauskas, Kristopher B. "Interannual variability of sea surface temperature in the eastern tropical Pacific Ocean and Central American rainfall." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7706.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Atmospheric and Oceanic Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Brown, Jaclyn Nicole School of Mathematics UNSW. "The kinematics and dynamics of cross-hemispheric flow in the Central and Eastern Equatorial Pacific." Awarded by:University of New South Wales. School of Mathematics, 2005. http://handle.unsw.edu.au/1959.4/20831.
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This thesis concerns two topics: the kinematics of Pacific cross-equatorial flow ??? the location, timing and magnitude of the flow; and their dynamics???what are the driving forces controlling the flow? Despite extensive observations in the central and eastern Pacific, observations of these flows remain contradictory. We use output from an Ocean General Circulation Model (OGCM) viewed from a Lagrangian framework on density layers. This addresses the problem of high variability due to features such as Tropical Instability Waves. The annual mean flow is found to be southward nearly everywhere, east of 140??W. Flow becomes stronger in the second half of the year due to a bolus transport of very light surface water, introduced by Tropical Instability Waves. A Tropical Cell pattern occurs along the equator that does not require diapycnal downwelling. From 160??E to 160??W the annual mean flow is northward, occurring mostly in the mixed layer, appearing to originate partly from the Equatorial Undercurrent surfacing in the east. The northward flow is strongest in March and becomes southward in September. The wind stress and nonlinear terms are shown to be the key driving features, with a prescribed biharmonic Smagorinsky horizontal friction scheme having negligible impact. From 160??E to 160??W, the flow is partly accounted for by an Ekman forcing, with the curl of the nonlinear term providing a crucial additional torque, more than doubling the magnitude in some instances. From 160??W to 120??W the wind stress curl provides a weak southward flow of about 1 Sv, which increases by the nonlinear addition to around 5 Sv. The curl of the steady component of the nonlinear term, derived from annual mean currents, is similar in structure to the total nonlinear term, but higher in magnitude. The structure of the variable term, which was mostly of opposite sign to the steady term, suggests damping occurs in place of friction. While our study is limited to an examination of the model's characteristics, our results provide important clues to the observed flow patterns not resolved by present-day measurements. This study also highlights the importance of time-space variability and both horizontal and vertical density structure in controlling the flow and its feedback on the system.
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Farrar, J. Thomas (John Thomas) 1976. "Air-sea interaction at contrasting sites in the Eastern Tropical Pacific : mesoscale variability and atmospheric convection at 10°N." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39009.
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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), 2007.Includes bibliographical references (p. 153-166).
The role of ocean dynamics in driving air-sea interaction is examined at two contrasting sites on 125°W in the eastern tropical Pacific Ocean using data from the Pan American Climate Study (PACS) field program. Analysis based on the PACS data set and satellite observations of sea surface temperature (SST) reveals marked differences in the role of ocean dynamics in modulating SST. At a near-equatorial site (3°S), the 1997-1998 El Nifio event dominated the evolution of SST and surface heat fluxes, and it is found that wind-driven southward Ekman transport was important in the local transition from El Nifio to La Nifia conditions. At a 10'N site near the summertime position of the Inter-tropical Convergence Zone, oceanic niesoscale motions played an important role in modulating SST at intraseasonal (50- to 100-day) timescales, and the buoy observations suggest that there are variations in surface solar radiation coupled to these mesoscale SST variations. This suggests that the mesoscale oceanic variability may influence the occurrence of clouds. The intraseasonal variability in currents, sea surface height, and SST at the northern site is examined within the broader spatial and temporal context afforded by satellite data.
(cont.) The oscillations have zonal wavelengths of 550-1650 km and propagate westward in a manner consistent with the dispersion relation for first baroclinic mode, free Rossby waves in the presenice of a, mean westward flow. The hypothesis that the intraseasonal variability and its annual cycle are associated with baroclinic instability of the North Equatorial Current is supported by a spatio-temporal correlation between the amplitude of intraseasonal variability and the occurrence of westward zonal flows meeting an approximate necessary condition for baroclinic instability. Focusing on 100N in the eastern tropical Pacific, the hypothesis that mesoscale oceanic SST variability can systematically influence cloud properties is investigated using several satellite data products. A statistically significant relationship between SST and columnar cloud liquid water (CLW), cloud reflectivity, and surface solar radiation is identified within the wavenumber-frequency band corresponding to oceanic Rossby waves. Analysis of seven years of CLW data and 20 years surface solar radiation data indicates that 10-20% of the variance of these cloud-related properties at intraseasonal periods and wavelengths on the order of 100 longitude can be ascribed to SST signals driven by oceanic Rossby waves.
by J. Thomas Farrar.
Ph.D.
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Petty, Kevin R. "The effects of synoptic factors on the intensities of tropical cyclones over the eastern North Pacific Ocean." The Ohio State University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/39803779.html.
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Taylor, Stephen V. "Northerly surface wind events over the eastern North Pacific Ocean spatial distribution, seasonality, atmospheric circulation, and forcing /." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237552.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed December 12, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 126-133).
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Böschen, Tebke [Verfasser]. "Deglacial to Holocene Changes in Eastern Equatorial Pacific Upper‐Ocean Dynamics – Indications from Foraminiferal (Isotope) Geochemistry / Tebke Böschen." Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/1050808398/34.
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Cardenas, Amores Jorge A. "Intraseasonal oscillations over the tropical western Pacific and eastern Indian Ocean for the northern summers of 1989-1991." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA284527.
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Bloomer, Stephen F. "Examination of the potential of seismic reflection data for paleoceanographic studies, case study from the eastern equatorial Pacific Ocean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/NQ65452.pdf.
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Nguyen, Xuan Vy [Verfasser]. "Application of genetic markers for identification of Halophila members and genetic variation of Halophila ovalis from Western Pacific to Eastern Indian Ocean / Xuan Vy Nguyen." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1057897493/34.
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Freund, Madeleine [Verfasser], Martin [Akademischer Betreuer] Visbeck, and Andreas [Gutachter] Oschlies. "Dispersion of a Tracer in the Eastern Tropical South Pacific - an Investigation of Interactions from the Benthic Boundary Layer to the Ocean Interior - / Madeleine Freund ; Gutachter: Andreas Oschlies ; Betreuer: Martin Visbeck." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1210052229/34.
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Kock, Annette [Verfasser]. "Nitrous oxide and hydroxylamine in the eastern tropical Atlantic and Pacific Oceans / Annette Kock." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1020283912/34.
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Bigot, Marianne. "Biogeochimie de la matiere organique dans l'estuaire du huang he et en mer de bohai." Paris 6, 1988. http://www.theses.fr/1988PA066083.
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Etude de l'origine du comportement de la matiere organique dans l'estuaire du huang he et en mer de bohai. Trois environnements sont envisages: le fleuve, la zone de turbidite maximum, la zone marine. Des analyses d'hydrocarbures non aromatiques, d'acides gras, de lactones et d'organochlores sont menees sur les fractions dissoutes et particulaires et le sediment. Les empreintes terrigenes, anthropiques et biologiques sont discutees. L'utilisation de methodes statistiques appliquees aux acides gras permet de comprendre et confirmer l'origine de ces composes. Une evolution de la qualite de l'environnement a ete effectuee. On presente un etat de reference de quelques contaminants organiques dans l'estuaire du huang he
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Torres, Edgar. "Effects of the fishing strategies developed by purse seine fleets on tropical tunas and on associated fauna in the eastern Atlantic and eastern Pacific oceans." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20029/document.
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Les pêcheries de thonidés représentent 7.9% de la production mondiale de produits de la mer. La plupart des stocks de thons sont pleinement exploités, et certains surexploités, et tous font face à une pression de pêche croissante. En raison de l'extension des zones de pêche, les évaluations des stocks dépendent en grande partie des captures commerciales. Toutefois, les données commerciales peuvent varier au cours du temps étant donné que les pêcheurs peuvent investir dans des engins de pêche et de l'équipement, s'établir au large des côtes, ou commencer à pêcher dans de nouvelles zones. Peu d'attention a été portée à la réponse des pêcheurs aux mesures de gestion ou aux conséquences de l'investissement technologique. L'objectif de la présente thèse est d'étudier les effets de stratégies de pêche et les réponses adaptatives des flottes de senneurs sur les thons tropicaux et la faune associée dans l'Océan Atlantic Est et dans l'Océan Pacifique Est. Dans un premier temps, nous montrons comment l'introduction de nouvelles technologies a eu un effet direct en augmentant la puissance de pêche, et un effet indirect en entraînant une modification des zones pêche. Nous étudions les effets de deux fermetures spatio-temporelles sur la dynamique de la flotte de senneurs européens. La première mesure de gestion a diminué les jours où des captures sont réalisées, les carrés avec capture à l'intérieur de la zone partiellement fermée, tandis que la pêche sur DCP a été redistribuée à l'extérieur de la zone et aucun changement n'a pas été enregistré pour la pêche sur banc libre. La seconde fermeture de pêche a entraîné une augmentation de toutes les activités de pêche en dehors de la zone. Dans l'Océan Pacifique Est, la flotte de senneurs mexicains a réagit à la fermeture d'une saison de pêche en diminuant le nombre de jours passés à quai. Par conséquent, le nombre de calées sur bancs associés aux dauphins a augmenté, et les niveaux de capture observés avant la mesure de gestion ont été maintenues. Nous analysons les effets des stratégies de senneurs de l'Union Européenne sur les prises accessoires. Nous mettons en évidence que la composition des espèces de requins capturés sous DCP et les raies capturées sur bancs libres ont changé au cours du temps. Nous estimons également que plusieurs types d'espèces peuvent être capturés par mode de pêcheTuna and tuna-like fisheries represent 7.9% of the global production of marine capture fisheries. Most tuna stocks are fully exploited and some overexploited, facing growing fishing pressures. Due to the extent of fishing grounds, stock assessments depend largely in commercial data, which vary over time because fishermen may invest in fishing technology, expand offshore, or start fishing in different areas. However, little attention has received the responses of fishermen facing management regulations or the effects resulting from technological investment. For these reasons the aim of this study was to investigate the effects of fishing strategies developed by purse seine fleets on tropical tunas and on associated fauna in the eastern Atlantic and eastern Pacific oceans. The continuous introduction of new fishing technology in the French fleet in the 1980s and the 1990s evidenced a direct increase in fishing power when large yellowfin in free-swimming school is targeted and likely an indirect effect by modifying the fishing grounds characterizing FAD-fishing on small size categories. The consequences of the two time-area closures on the spatio-temporal dynamics of the European Union fleet were investigated. The regulation on FADs resulted in a decrease in the days with catch and successful squares inside the restricted area, reallocating FAD-fishing outside the area while no change in free-swimming school fishing was observed. The no-take time-area increased all fishing activities outside the restricted area with apparently no gain in terms of protection of juveniles. In the eastern Pacific as a response to a closed season the Mexican fleet reduced days in port and consequently the number of sets on dolphin-associated schools increased, maintaining the catch levels observed before the regulation. The study of the effects of the EU fleet fishing strategies on bycatch over two time periods showed that the species composition of sharks caught on FADs and may be for rays caught on free-swimming schools changed over time. We also estimated the total number of species that can be potentially be caught by fishing mode
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Roa, Pascuali Carmen Liliana. "Mesoscale structure and dynamics of the tropical tuna's associated-environment in the Indian and the Eastern Pacific Oceans : comparative approach." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTS030.
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Le présent travail a pour but d'étudier la structuration à méso-échelle (de quelques kilomètres à quelques centaines de kilomètres) de l'environnement des trois espèces majeures de thons tropicaux, l'Albacore (Thunnus Albacares;YFT), le Listao (Katsuwonus Pelamis;SKJ) et le thon obèse (Thunnus obesus;BET), pêchés à la seine tournante dans les océans Indien et Pacifique Tropical Est (EPO), en fonction de leur tailles et leur distribution. Ces trois espèces représentent 20% et 13% des prises mondiales respectivement dans les 2 océans. Les prises par callées uniques sont utilisées pour évaluer séparément les caractéristiques environnementales de leur zones de pêche pour trois modes de pêche: sur banc libre (FS), objets flottants naturels (LOG) et sur dispositifs de concentration du poisson (DCP), ceci pour plusieurs tailles d'individus. Préalablement aux analyses, une double méthode statistique et d'expertise est utilisée pour la détection et la classification des fronts thermiques, utilisable à l'échelle des bassins océaniques, tandis que les tourbillons de méso-échelle, cycloniques et anticycloniques sont détectés par la méthode des winding angle. Les distances des prises à ces structures sont ensuite calculées. Nous trouvons que les fronts intenses concernent surtout les régions côtières et les fronts faibles l'océan du large, ce qui permet de prendre en compte des mécanismes de frontogénèse différents pouvant avoir un pouvoir attractif différemment sur les thons. En plus des composantes de méso-échelle, les variables classiques de l’environnement, les variables temporelles et celles liées à la pêche sont utilisées. Nous utilisons le modèle bayésien "Boosted Regression Tree” (BRT) suivant un schéma en 3 phases pour chaque océan pour explorer les réponses du niveau de prise pour chaque espèce et trois modes de pêche. La dominance relative est également explorée pour les prises sur FADs (O. indien) et FADs et FS (EPO) et montre des résultats similaires au niveau de prise. Tous les modèles BRT montrent que le niveau de prise est davantage relié à la variabilité environnementale pour les bancs libres que pour les FADs. Nous mettons en évidence pour la première fois l'importance des structures de méso-échelle sur la définition des habitats des thons, ce qui est confirmé par les faibles niveaux d'explication obtenus par les modèles de type « random », notamment dans l'océan indien. Pour les deux océans, les petits individus sont fortement associés aux tourbillons (distances <200km) tandis que les plus gros individus sont situés plus loin des tourbillons. Une faible influence des fronts thermiques est constatée dans l'Océan Indien tandis que l'opposé est trouvé pour le Pacifique, sauf dans les régions côtières où les forts fronts ont une influence importante. Différentes conditions environnementales sont observées dans des régions précises du Pacifique comme les upwellings côtiers, la bande équatoriale et le dôme du Costa Rica. Contrairement à l'Océan Indien, où les zones de pêches sont relativement homogènes en terme de température et chlorophylle de surface, ces deux paramètres influencent nettement plus la distribution des thons dans le Pacifique. Dans l'Océan Indien, le pourcentage total des contributions relatives par catégories de variables est de 34 % pour les variables de méso-échelle, de 39 % pour les variables classiques et de 27 % pour les autres (temporelles et pêche). Pour le Pacifique Est, même si la méso-échelle est importante (37%) les autres variables dominent en contribution relative (55 % et 8%).Mots clé : Thons tropicaux, taille, Océan Indien, Océan Pacifique Est, environnement, méso-échelle, senne tournante, modes de pêcheThis study provides an approach to the comprehension of the mesoscale structure in the habitat patterns of three major tropical tunas species, yellowfin (Thunnus albacares; YFT), skipjack (Katsuwonus pelamis; SKJ) and bigeye (Thunnus obesus: BET). These species, mainly caught by the purse seiner's fishery worldwide, represent 20% and 13% of the world total production for the Indian and the Eastern Pacific oceans respectively. Single set records from this fishing gear in both, the Indian and in the Eastern Pacific oceans, were used to separately evaluate the environmental characteristics of their fishing grounds for three fishing modes: free school (FS), log (LOG) and fish aggregated devices (FADs) and several individual sizes. Prior to the analyses, a statistical expert-based method was applied to detect and classify thermal fronts at basin scale whereas the anticyclonic and cyclonic eddies are detected, based on the winding angle method. The distances of the catch positions from these structures were then calculated. We found that strong fronts are mostly found in coastal regions and weak fronts in the open ocean. This allows the consideration of the frontal intensity helps to spatially differentiate mechanisms of frontogenesis than may attract tunas. In addition to these mesoscale components, classic, temporal and fishery-related variables were added to describe the fishing environment. We used the Boosted Regression Tree (BRT) method to create a three step modeling scheme for each study area in order to explore the responses of the catch level and size for the different fishing modes, also considering the effect of randomly distributed catch positions, in order to separately estimate the mesoscale effects. The relative dominance of each species is also explored and globally shows similar results than for the catch level. All BRT models show that the catch level was better explained by the environment for free school (FS) than for FADs fishing modes and that the differences in distribution were more important among fish-sizes than among species. We quantify for the first time the strong influence of the mesoscale in determining tuna's habitat, confirmed by the poor explanation obtained in all random models, mainly for the IO. For both oceans, small individual were strongly related with the proximity to mesoscale eddies (<200 km) whereas the larger individuals area found at larger distances. A low influence of mesoscale fronts was found mainly for the Indian ocean whereas the opposite pattern was observed for the EPO, except in the coastal regions where strong fronts become important. Different environmental conditions were observed in well defined sub-regions as the coastal upwelling, the equatorial tongue, and the Costa Rica Dome. Contrarily to the Indian ocean were the fishing grounds are relatively homogeneous in term of Sea Surface Temperature and chlorophyll concentration, these two parameters highly influence the tuna distribution in the EPO. In the Indian Ocean, the total percentages of relative contribution by category of variables for all models were 34% for the mesoscale, 39% for the classical variables and 27% for others (temporal and fisheries related). For the Eastern Pacific, even if mesoscale remains important (37%), the most relevant ones were the classical variables with 55% of the total relative contribution (8% for others). Key word: Tropical tunas, Indian Ocean, Eastern Pacific Ocean, mesoscale, purse seiner, species, fish-size, fishing mode
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Loh, Ai Ning. "Distribution, Partitioning and Fluxes of Dissolved and Particulate Organic Carbon, Nitrogen and Phosphorus in the Eastern North Pacific and Southern Oceans." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539617737.
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Zindler, Cathleen [Verfasser]. "Short-lived trace gases (DMS, isoprene, acetaldehyde and acetone) in the surface waters of the western Pacific and eastern Atlantic Oceans / Cathleen Zindler." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1034822705/34.
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Margalef, Marrasé Olga. "The last 70 kyr of Rano Aroi (Easter island, 27ºS) peat record: New insights for the Central Pacific paleoclimatology." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/146186.
Full textAbstract:
The PhD entitled “Last 70kyr of Rano Aroi (Easter Island, 27ºS) peat record: New insights for Central Pacific paleoclimatology” presents an environmental and climate reconstruction of Easter Island during the last 70.000 years. To accomplish this purpose, two peat cores of 14 and 4 meters have been retrieved from the center and the margin of the Rano Aroi peatland. Facies description and age model allowed us to decipher that the peat started accumulating 70.000 years ago, what means that this is the oldest peat record recovered up to the moment over the Southern Pacific. To investigate changes in the type of accumulated peat we determined total carbon, nitrogen and sulfur (TC, TN, TS) of organic matter as well as stable isotope values of each element (delta13C, delta15N, delta34S). In order to decipher the composition of the mineral content, X-Ray Fluorescence measurements was performed over the cores, obtaining the quantity of Ca, Fe and Ti. Additionally, the concentration of the major, minor and trace elements was determined by spectrometry (ICP-AES). The geochemical approach was complemented by the study of macrofossil (plant or animal remains as seeds or insects) and pollen content, what permitted to reconstruct vegetation changes on the mire and the island. The combination of geochemical and biological proxies defined three main hydric conditions (flood, drought and baseline conditions) of the peatland that have been alternated along Late Pleistocene and Holocene.
During MIS 4 (70 to 60 kyr BP in Rano Aroi), the hydric and environmental conditions in the mire were stable and resembled mire baseline conditions. Open grasslands covered Rano Aroi catchment area and C4 Poaceae dominated the mire. Early MIS 3 (60 to 40 cal kyr BP in Rano Aroi) was marked by the onset of wet events. During the first half of MIS 3 and probably driven by the wetter and warmer conditions Asteraceae and other small trees became gradually more abundant, forming small and scattered forests around the Terevaka volcano, while C3 peat forming plants colonized the Aroi mire. Late MIS 3 was a very dry period, which led to peat oxidation and exposure shortly after 39 cal kyr BP. These conditions changed on early MIS 2 (27.8–19 cal kyr BP). The water table recovered and peat accumulation resumed under C3 plant dominance. The evidence of the onset of deglaciation is concordant with Raraku Lake environmental development and was dated at 17.5 cal kyr BP in both sites. The regional mid-Holocene dry period is well characterized at Rano Aroi from 5 to 2.5 cal kyr BP.
The correlation between Rano Aroi record and other circumpacific sites suggests important changes in the atmospheric or oceanic circulation on Central Pacific during Late Pleistocene. In particular, the Rano Aroi record indicates that the episodes of maximum precipitation over the island correlate with North Atlantic Heinrich stadials and other stadials. During these stadials, the Intertropical Convergence Zone (ITCZ) migrated to the south while the South Pacific Convergence Zone (SPCZ) shifted eastwards provoking the arrival of storm systems over the island. In accordance to this atmospheric and oceanic restructuration, Rano Aroi wet events also correlated with periods of a reduced Sea Surface Temperature (SST) gradient along the Equator. This fact indicates that more humid conditions over the Easter Island region occurred when the Walker circulation was reduced. The Central Pacific climate was also influenced by high latitude dynamics, like the changes in Intermediate Antarctic Water formation and the position of the Southern Westerlies.La tesi titulada: "Last 70kyr of Rano Aroi (Easter Island, 27ºS) peat record: New insights for Central Pacific paleoclimatology" presenta una reconstrucció climàtica i ambiental de l’illa de Pasqua (Rapa Nui) pels darrers 70.000 anys. Per aquest propòsit es van estudiat dos testimonis de 14 i 4 metres, extrets del centre i marge de la torbera de Rano Aroi. Per determinar els canvis en el tipus de torba acumulada es van obtenir els perfils de carboni, nitrogen i sofre total (TC, TN, TS) així com els corresponents isòtops estables (delta13C, delta 15N, delta 4S). La variabilitat en el contingut de Calci, Ferro i Titani (Ca, Fe, Ti) es va obtenir amb mesures de Fluorescència de Rajos X mitjançant core-scanner. Usant espectrometria (ICP-AES) es va determinat la concentració d’elements majoritaris, minoritaris i traça de la fracció inorgànica. El conjunt d’indicadors geoquímics es va complementar amb l’estudi de macrofòssils (restes animals i vegetals com insectes o llavors) i la determinació del contingut pol•línic del registre. La integració de les dades geoquímiques i biològiques ha permès establir tres condicions hídriques (inundació, sequera, condicions de base) de la torbera que s’han anat alternant durant els darrers 70.000 anys. Durant el MIS 4 la vegetació de la conca consistia en amplis prats de Poaceae i la formació de la torba es produïa per acumulació de restes de plantes de tipus C4. L’inici del MIS 3 va estar caracteritzat per l’ocurrència d’episodis de forta precipitació. Durant aquest període, les creixents temperatures i l’elevada precipitació varen afavorir l’establiment d‘Asteraceae formant possiblement petites clapes de bosc al voltant de Rano Aroi. La vegetació de tipus C3 va colonitzar la torbera, tot produint un canvi en la isotopia de carboni present fins a dia d’avui. El final del MIS 3 va ser caracteritzat per un llarg període sec situat en algun moment entre els 39 i els 31 kyr cal BP. A l’inici del MIS 2, la làmina d’aigua de la torbera es va recuperar tot reactivant l’acumulació de torba. L’Holocè es registra com a un període relativament sec, interromput puntualment per un episodi humit als 5.8 kyr cal BP. La correlació de la historia ambiental de Rano Aroi amb altres registres del circumpacific han permès deduir canvis en la circulació oceànica i atmosfèrica del Pacífic Central. En concret, el registre de Rano Aroi indica que els episodis de màxima precipitació de l’illa correlacionen amb períodes estadials freds definits a l’Atlàntic Nord al llarg del darrer cicle glacial. Durant els estadials, la zona de convergència intertropical (ITCZ) es va desplaçar cap el sud mentre que la zona de convergència del Pacífic Sud (SPCZ) va migrar en direcció est. Aquesta reestructuració atmosfèrica va comportar una major arribada de tempestes ciclòniques a l’illa. El clima del Pacífic central també es va veure influenciat per les dinàmiques de altres latituds, com els canvis en la formació d’aigües intermèdies antàrtiques o la posició dels vents meridionals de l’oest.
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Dekaezemacker, Julien. "Etude de la fixation d'azote dans les environnements "déficitaires en azote" : Contribution des diazotrophes unicellulaires et contrôle par la disponibilité nutritive." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4098.
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Ce travail de thèse a pour but d'étudier la fixation d'azote marine dans les environnements riches mais déficitaires en azote (N), comparé au phosphore (P) dans un rapport N:P<16, grâce à l'utilisation d'approches complémentaire en culture in vitro et sur le terrain in situ. La première partie de ce travail a consisté à évaluer la réponse de la fixation d'azote de la cyanobactérie unicellulaire diazotrophe Crocosphaera watsonii face à des concentrations micromolaires en azote inorganique dissous (DIN) supposées inhiber l'activité de fixation d'azote : - suite à un apport sporadique, ou, - après une longue période d'acclimatation. Les résultats de ces études n'ont pas permis d'observer une inhibition des activités de fixation d'azote de cet organisme, laissant supposer que ce processus pourrait être actif dans une zone de l'Océan ayant ces même caractéristiques biogéochimiques : le Sud Est Tropical de l'Océan Pacifique (ETSP). En effet, cette zone est une des trois plus grandes zones de minimum d'oxygène (OMZ) de l'Océan et d'intenses processus de pertes de N (dénitrification et anammox) y ont lieu, résultant en un déficit de N par rapport au P. Des études présumaient que des processus inverses, de gains de N par la fixation d'azote, pourraient y être actifs mais aucune mesure à l'échelle du bassin n'y avait été faite car la fixation d'azote n'était supposée se produire que dans les environnements oligotrophes, comme les gyres subtropicaux. Dans le cadre d'un projet international, des missions océanographiques ont pu avoir lieu dans cette zone en Février 2010 pendant un évènement El Niño et en Mars-Avril 2011 pendant un évènement La NiñaThe objectif of these thesis was to study dinitrogen fixation in marine environments rich but deficient of nitrogen (N) compared to phosphorus (P) in a ratio N:P<16, by using complementary approaches in culture in vitro and in the field in situ. The first part of this work was to evaluate the response of nitrogen-fixing unicellular Cyanobacteria Crocosphaera watsonii faced with micromolar concentrations of dissolved inorganic nitrogen (DIN) supposed to inhibit nitrogen fixation activity : - after sporadic input, or, - after a long period of acclimatization. The results of these studies have failed to observe the inhibition of nitrogen fixation activities of this organism, suggesting that this process could be active in an area of the Ocean with these same biogeochemical characteristics : the Eastern Tropical South Pacific (ETSP). Indeed, this area is one of the three largest oxygen minimum zones (OMZ) of the Ocean, where intense processes of N losses (denitrification and anammox) took place, resulting in a deficit of N compared to P. Studies assumed that the inverse process, gain of N by nitrogen fixation, could be active in the ETSP but no measurements across the basin have been performed because nitrogen fixation was assumed to occur only in oligotrophic environments, such as the subtropical gyres. In the framework of an international project, cruises took place in this area in February 2010 during a El Niño event and in March-April 2011 during a La Niña event. Results of these two cruises have confirmed that nitrogen fixation was unexpectedly active with an intensity comparable to those reported in oligotrophic areas
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Leonardi, Alan P. "Interannual variability in the Eastern subtropical Pacific Ocean." 2000. http://catalog.hathitrust.org/api/volumes/oclc/50069828.html.
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Robertson, Angela K. "EASTERN EQUATORIAL PACIFIC PRODUCTIVITY VIA TWO GEOCHEMICAL PROXIES." Thesis, 2012. http://hdl.handle.net/1805/2740.
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Indiana University-Purdue University Indianapolis (IUPUI)Drivers that influence oceanic productivity are not clearly constrained. However, sea level changes during glacial cycles have been proposed as a potential driver for productivity variations observed over warm and cold climate periods. In order to determine this, additional oceanic paleoproductivity data collection is necessary to estimate the ocean’s feedback in response to a dynamic climate. The eastern equatorial Pacific (EEP) is an ideal site for productivity studies due to its high levels of nutrients and deep upwelling. This research examines the phosphorous and barite geochemisty of four EEP sites while also comparing the sites’ glacial and interglacial productivity variations to the geochemistry and productivity results of an independent central equatorial pacific site. Phosphorus and other elemental data were collected from sites 845, 848, 849, and 853 (ODP Leg 138). Using a Ba/Ti and P/Ti proxy (“excess” proxies), distinct productivity variations during glacial and interglacial periods were observed. While the age model for these sites has been estimated, the observed variations more than likely agree with high productivity during glacial periods and lower productivity during interglacial periods. Central equatorial Pacific cores RR0603-03TC and RR0603-03JC (IODP site survey cruise for Proposal 626) have been used as a reference for geochemical concentration parameters, as well as a comparison tool for productivity variations among the central and eastern sites. The central equatorial geochemistry results provided support for sea level changes driving paleoproductivity variations. The similar variation patterns displayed by the EEP’s geochemical data in this research could provide additional support for this hypothesis.
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Singh, Ajay 1980. "Eastern Equatorial Pacific Ocean Sedimentation: Investigating Constant Flux Proxies." Thesis, 2012. http://hdl.handle.net/1969.1/148258.
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Age-model derived sediment mass accumulation rates (MARs) are consistently higher than 230Th-normalized MARs in the Equatorial Pacific Ocean during the past 25 ka. The offset, being highest in the Panama Basin, suggests sediment redistribution in this region is prominent. I test the hypothesis that downslope transport of sediments from topographically highs that surround the Panama Basin is the cause of higher-than-expected xs230Th inventories in the deeper parts of the basin. There is little difference in xs230Th inventories between the highest and lowest reaches of the basin suggesting that the topographic highs did not serve as a source of xs230Th. A spatial analysis suggests that there may be an enhanced scavenging of xs230Th closest to the equator in productive waters.
To examine whether lateral mixing of productive equatorial waters with adjacent waters delivers xs230Th to the Panama Basin, I measured dissolved 230Th in eight deep-water casts within the Guatemala, Panama, and Peru Basins along a meridional transect at ~86°W. Below 1000 m, the Panama Basin shows the highest deficit (~50%) of 230Th in deep waters assuming a reversible exchange of 230Th between dissolved and sinking particulate matter. Peru Basin waters have a larger range of dissolved 230Th concentrations (7.9-16.5 fg/kg) than that within Panama Basin waters (5.7-7.1 fg/kg). There is a progressive decrease, suggesting advection, in average dissolved deep-water (>1000 m) 230Th concentrations from the southernmost sites in the Peru Basin toward the Panama Basin. My calculations suggest that advected 230Th is between 15-30% of the total 230Th being produced within waters of the Panama Basin itself.
In the Panama Basin, the averaged biogenic barium and opal MARs suggest that productivity was greater during the Holocene (0-13000 years) than that during the last glacial (13000-25000 years) suggesting higher productivity during the Holocene. Uauth, however, is higher in sediments deposited during the last glacial than in those deposited during the Holocene, suggesting that low bottom water oxygen contents rather than respiration of organic matter drives Uauth enrichment. This oxygen depletion during the last glacial suggests that bottom waters were enriched in respired carbon, which, in turn, could be a driver of lower glacial atmosphere pCO2 values.
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Tonin, Hemerson Everaldo. "Atmospheric freshwater sources for eastern Pacific surface salinity." 2006. http://catalogue.flinders.edu.au/local/adt/public/adt-SFU20061031.080144/index.html.
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Mack, Andrew P. "High-frequency internal waves in the upper eastern equatorial Pacific." 1997. http://catalog.hathitrust.org/api/volumes/oclc/41182637.html.
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Thum, Nicolai. "Air-sea heat exchange along the northern sea surface temperature front in the eastern tropical Pacific." Thesis, 2001. http://hdl.handle.net/1957/28703.
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The atmospheric response to the oceanic forcing in the eastern Pacific along
the northern equatorial sea surface temperature (SST) front is investigated in
terms of sensible and latent heat flux during the 6-month period 28 July 1999
through 27 January 2000. Of particular interest is the atmospheric boundary
layer (ABL) response to oceanic Tropical Instability Waves (TIWs) that distort
the SST front during May through January in normal years. In previous studies,
time series of boundary layer properties clearly show the influence of TIWs but
the relationship to spatial patterns of SST and wind stress has been inferred only
from sparse in situ data.
In this study, satellite observations are used to composite in situ data from
moorings to compensate for the lack of a spatially dense mooring array. The variability
in the position of the SST front caused by propagating TIWs enables fixed
mooring locations to measure the atmospheric boundary layer (ABL) response
from a large range of locations relative to the front. The satellite data enable
determination of the precise location of the mooring relative to the front. The
advantage of this strategy is the recurring measurement of the ABL response to
the SST front over the six month period considered here.
The results indicate that the TIW-induced perturbations of sensible and latent
heat flux are spatially shifted in phase towards the east relative to the perturbations
of SST. The maximum fluxes are not centered directly over the warmest
water, but are shifted towards the portion of the frontal region where a disequilibrium
boundary layer is expected due to the advection of colder air from the
equatorial region. The changes of sensible and latent heat fluxes across the SST
front have magnitudes of about 11 Wm⁻² and 126 Wm⁻², respectively.
The sensible and latent heat flux patterns are interpreted in two complementary
ways: (1) as an atmospheric response to the change of oceanic forcing as
air flows across the SST front; and (2) as the atmospheric response to westward
propagating TIWs along the SST front.Graduation date: 2001
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Snoeckx, Hilde. "Late Pleistocene history of ocean-atmosphere interaction in the eastern Equatorial Pacific." 1996. http://catalog.hathitrust.org/api/volumes/oclc/37357033.html.
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Hale, Sarah Beth. "PALEOPRODUCTIVITY VARIATIONS IN THE EASTERN CENTRAL EQUATORIAL PACIFIC OCEAN ON GLACIAL TIMESCALES." Thesis, 2008. http://hdl.handle.net/1805/1671.
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Indiana University-Purdue University Indianapolis (IUPUI)Paleoproductivity records during the late Pleistocene are sparse. The equatorial Pacific and the Southern Ocean are collectively responsible for the majority of the new production in the oceans. The nutrient and carbon mass balances of these regions must be constrained in order to fully understand net global biological productivity on glacial timescales. The geochemistry of two east-central equatorial Pacific Ocean cores (02° 33.48 N; 117° 55.06 W) and (00° 15.42 S; 113° 00.57 W) are used to examine changes in biological productivity due to nutrient upwelling on glacial timescales during the Pleistocene. The cores were recovered in March 2006 on the AMAT03 cruise, a site survey cruise for IODP Proposal 626. The total concentrations of Ca, Ti, Fe, Al, P, Ba, S, Mg, Sr, Zn and Mn were determined by a total sediment digestion followed by analysis by inductively coupled plasma-atomic emission spectrometry (ICP). Original solid forms of P for 34 evenly spaced samples throughout one core were determined using the P Sequential Extraction technique. This study is attempting to compare upwelling and productivity records by determining temporal records of nutrient proxies, using Latimer and Filippelli (2006) which focused on the Southern Ocean. Equatorial upwelling and Southern Ocean upwelling both appear to exhibit strong glacial timescale variability. The P geochemistry results indicate that the P signal is largely biological. The equatorial Pacific evidence, in accordance with Southern Ocean patterns, supports a nutrient budget-driven productivity signal over time. Gabriel M. Filippelli, Ph. D, Committee Chair
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Lee, Dong-kyu. "The linear and non-linear baroclinic instability in the eastern North Pacific." Thesis, 1987. http://hdl.handle.net/1957/27794.
Full textAbstract:
Using a linear quasi-geostrophic model of large scale spiraling flow and vertical density
gradient in the eastern North Pacific, we evaluate the complex dispersion relationships
for quasi-geostrophic waves. Our calculations indicate that the geostrophic circulation
of the eastern North Pacific can locally convert potential energy to mesoscale
kinetic energy on a scale comparable to the observed space and time scale and should
be a source of eddy energy, distant from the eddies spawned by the Kuroshio and near
the topographic features. But the local growth rates by linear stability analysis do not
relate to the observed features of eddy kinetic energy in the eastern ocean; eddy kinetic
energy increases to the south and has a maximum in the subtropical region.
The non-linear baroclinic instability is analyzed using a three-layer quasi-geostrophic
numerical model. Three experiments with different idealized initial mean
flow are performed. Local energetics are calculated to highlight the difference between
the southward return flow and westward return flow regions. It is found that the
boundary flux of mean to eddy kinetic energy conversion is the main differences
between two regions: it is large in the westward return flow region but is small in the
southward return flow region. Two waves with different characteristics are found: the
short waves (periods of 120 days), that propagate to the west and form several wave
trains parallel to the southern boundary, and the long waves (periods of 200 days),
that propagate to the south-west. These two waves are remarkably similar to the
measurements of open ocean eddies at 28°N and 152°W. It is shown that there are high
eddy activities in the southward return flow regions by influxes of eddies from other
areas, but the southward return flow region is vacant in eddies by outflows of the westward
and south-westward propagating waves.Graduation date: 1987
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Wu, Peng 1981. "Interannual variability of tropical cyclone activity over the eastern North Pacific." Thesis, 2006. http://hdl.handle.net/10125/20706.
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Fan, Chen-Shuo, and 范辰碩. "Inter-annual Rainfall Variability of Specific Area In The Eastern Equatorial Pacific Ocean." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/jeeyw7.
Full textAbstract:
碩士國立中央大學
大氣科學學系
105
This research is inspired by Floating City Project which is going to be implemented by American and Netherland Cooperated Institution in 2020. The floating city has been planned to construct over the eastern equatorial Pacific Ocean near Central America in the project. Consider to the future water resource problem of the floating city, this research is dedicated to understand inter-annual precipitation variation over Target Area (6N-12N, 86W-94W) in rainy season. Target Area is actually a place where the floating city would be built in 2020. In this research, climatology rainy season of Target Area has been classified as three periods. Period-1, Period-2 and Period-3 are represent of May-June, July-August and September-October respectively. Wet years and dry years are picked up in each period, then analysis of atmospheric and oceanic gridded datasets would be conducted through composite analysis method according to these wet and dry years. Follow the diagnostic results of moisture budget over Target Area, Period-1 and Period-2 has dry advection and downward motion anomaly contribution for less precipitation in Dry year. Conversely, wet advection and upward motion anomaly contributed for more precipitation in Wet year. With regard to Period-3, contribution intensity of vertical motion anomaly is much higher than Period-1 and Period-2, but for advection term contribution is much less than former two periods. From the results of correlation analysis between global sea surface temperatures (SST) and Target Area precipitation, precipitation has found to have related with Pacific and Atlantic SST. Therefore, this research further applied Empirical Orthogonal Function (EOF) with SST datasets to separate out the most three significant climate oscillation signals of Pacific and Atlantic Ocean. Through correlation and multi-regression analysis of climate oscillation signals and precipitation, Period-1 and Period-2 precipitation are demonstrated that affected by Central Pacific ENSO (CP), Eastern Pacific ENSO (EP) and North Atlantic Oscillation (NAO). When getting into Period-3, precipitation only affected by CP and EP in this time. Especially for Walker Circulation variation during CP and EP events, Atlantic Subtropical High variation during NAO event, these phenomenon are the main cause of vertical motion and advection anomaly contribution, it is also consistent with the diagnostic results of moisture budget.
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Kaupp, Lauren Johanna. "Distributions of dissolved iron and aluminum in the eastern equatorial Pacific : results from the 2004 biocomplexity cruise." Thesis, 2005. http://hdl.handle.net/10125/20796.
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Olson, Robert James. "A bioenergetics analysis of yellowfin tuna (Thunnus albacares) predation in the eastern Pacific Ocean." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23587892.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1990.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 142-154).
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Finney, Bruce Preston. "Paleoclimatic influence on sedimentation and manganese nodule growth during the past 400,000 years at MANOP Site H (eastern equatorial Pacific)." Thesis, 1986. http://hdl.handle.net/1957/26611.
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Yao, Chiou-Ju, and 姚秋如. "Population variation and phylogeography of pantropical spotted dolphin (Stenella attenuata) in western and eastern tropical Pacific Ocean." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/ukd8rg.
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Bemis, Bryan Edwin. "Stable isotopic records of venerid bivalve shells environmental information from the eastern Pacific Ocean and southern Caribbean Sea /." 1992. http://catalog.hathitrust.org/api/volumes/oclc/31747508.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1992.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 53-57).
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Lin, Hsin-Jung, and 林新榮. "Comparison of the fishing effect of Circle and J-style hooks for tuna longline fishery in eastern Pacific Ocean." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/89161504065517257589.
Full textAbstract:
碩士國立高雄海洋科技大學
漁業生產與管理研究所
95
Many studies indicated that a conversion from J-style hook to circle hook might reduce the fishing mortality in tuna longline fishery. But the effects of this change on catch rate of target species were still unclear. To evaluate the effects, we carried out 31 sets of comparative fishing test from 26 April, 2006 to 06 June, 2006 by using a commercial vessel operated in the eastern Pacific Ocean. This study tried to compare the fishing effects on any caught species between using two sizes of traditional tuna hooks (standard Taiwan hook sizes：3.4 and 4.2 inch) and two sizes of circle hooks (size 4.0 and 4.2 inch). Also the bathythermographs were used to record the temperature-depth data during experiments. The suggestions obtained from results are as follows: (1) After the soak time of each type of hook was standardized, catch rates of both Circle hook types (size 4.0 inch and 4.2 inch) for any fishing species had no significant difference (P>0.05). Catch rates for billfishes between using Circle hook (size 4.2 inch) and J-style hook ( size 4.2 inch) has significant difference (P<0.05) while catch rates for other fishing species had no significant difference(P>0.05) between them. (2) All types of hook were more likely to lodge in the mouth for tuna and skipjack species, but other fishing species were more likely to be hooked in the internal position. The possibility of hook lodged in the mouth for any fishing species among using any hook type had no significant difference (P>0.05). It also showed a higher survival rate by using either small hooks (3.4 and 4.2 inch J-style hook) or circle hooks (4.2 inch of Circle and J-style hook). (3) The body lengths of captured bigeye tuna between all hook types were not significant difference (P>0.05). But the body length of yellowfin tuna caught by 3.4 inch J-style hook had longer than those caught by 4.2 inch J-style hook (P<0.05), and it caught by 4.2 inch Circle hook had also longer than those caught by 4.2 inch J-style hook (P<0.01). In this study, the results indicated that a change from 4.2 inch J-style hook to 4.2 inch Circle hook had no significant impact on fishing rates. Furthermore, usage of circle hooks instead of conventional tuna hooks could increase the fishing length for tunas and survival rate at haulback. Therefore, promotion of using circle hook could be extended from offering the training course for fishers in Taiwan tuna longline fishery, and would conform to the trend of international conservation.
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Fu, Shin-Chin, and 傅信欽. "Reproductive biology of skipjack tuna, Katsuwonus pelamis, in the western and central Pacific Ocean and waters off eastern Taiwan." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/24599148657224532133.
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Pedrozo, Raul A. F. "The International Dolphin Conservation Act of 1992 : unreasonable extension of U.S. jurisdiction in the Eastern Tropical Pacific Ocean (ETP) fishery." Thesis, 1993. http://hdl.handle.net/10945/24185.
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Lin, Fu-Chia, and 林富家. "Age and growth of skipjack tuna, Katsuwonus pelamis, in waters off eastern Taiwan and the western and central Pacific Ocean." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/61118788372671946929.
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Wolter, Klaus. "Modes of surface circulation and climate over the Tropical Atlantic, Eastern Pacific, and Indian Oceans." 1987. http://catalog.hathitrust.org/api/volumes/oclc/16799463.html.
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Chen, Hui, and 陳卉. "Population genetic structure and demographic history of blue marlin, Makaira nigricans, in the Pacific and eastern Indian oceans." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/33319298243793606016.
Full textAbstract:
博士國立臺灣大學
海洋研究所
104
Blue marlin (Makaira nigricans) is a species that inhabits tropical, subtropical, and temperate waters worldwide. While blue marlin is economically important for fisheries, there are regions in this species’ distribution where little is known about its population structure. This is especially true in the Pacific Ocean, which yields the largest catch of blue marlin, and in the Indian Ocean, where catch has increased consistently over the years and the area is commonly overfished. Sampled Taiwan local market blue marlin shows two morphological characteristics of thick or thin scales. Phylogenetic analysis for taxonomy by mitochondrial DNA (mtDNA) cytochrome b (cyt b) (1140 bp) and control region (CR) (905 bp), these two morphological characteristics of the blue marlin belong to the same species. A total of 183 blue marlin was collected from three Pacific localities, eastern Pacific (EP) (n= 54), western North Pacific (WNP) (n= 56), and South China Sea (SCS) (n= 40) and one Indian Ocean locality (EI) (n= 33), analysis of mtDNA CR revealed that these are both of the ubiquitous clade. Currently blue marlin in the Pacific and Indian Oceans are managed as two distinct management units (the Western and Central Pacific Fisheries Commission [WCPFC] and the Indian Ocean Tuna Commission [IOTC]). This study investigated the genetic structure of blue marlin population inhabiting the Pacific and eastern Indian Oceans based on mtDNA cyt b and CR sequence variation. The results of pairwise ΦST, hierarchical analysis of molecular variance (AMOVA), and spatial analysis of molecular variance (SAMOVA) all support that there is no population differentiation among eastern Indian and Pacific blue marlin, thereby the population are comprised of a single stock. All eastern Indian and Pacific blue marlin possess high haplotype diversity (h) and low nucleotide diversity (π). Neutrality tests, pairwise mismatch distribution, and Bayesian skyline analysis all indicate that eastern Indian and Pacific blue marlin have undergone a rapid population expansion on the order of 0.30 to 0.74 million years ago. This study demonstrates that blue marlin in the Pacific and eastern Indian Oceans constitute a single genetic stock, which provides very important information for stock assessment purpose and for further conservation and sustainable utilization of this resource.