Дисертації: "Survival at sea – Indian Ocean"

1

Karunatilleke, Upali. "The law of the sea and the Indian ocean." Thesis, Southampton Solent University, 2004. http://ssudl.solent.ac.uk/775/.

Повний текст джерела

Анотація:

Arvid Pardo, the ambassador of Malta presented a revolutionary concept regarding "the sea bed and the ocean floor" when he warned the United States that it must be treated as a "Common heritage of mankind" otherwise it is an area that could lead to conflict between states leading to wars that would spell the end of humanity. The United States took serious note of the underlying potential truth of this warning, sponsored a number of conventions of the Law of the Sea which led to the adoption of UNCLOS III, which was unique in so many respects but the most notable was, it served as a constitution fot the management of the ocean. Two main functions of the sea, namely fisheries and the prevention of pollution, whether land based or vessel sourced, reseived the attention of the world community that participated at the conference that prompted them to adopt a legal framework to establish a conservation and management programme in relation to both subjects. Coastal states were conferred greater jurisdiction, with an expansion of the territorial sea, contiguous sea and a new concept of a 200 nautical mile exclusive economic zone which specified new rights and obligations to all users of the sea, be they coastal states, flag states, port states or any other user. They had to abide these rights and obligations as part of international law. The implementation of these rights and obligations needed the best scientific evidence and knowledge available as well as the cooperation of competent international organisations. It was further envisaged that regional and sub-regional arrangements would be a benevolent method of implementing and monitoring the rights and obligations of states. It was observed that the northern hemisphere states, particularly in the north Atlantic, north Pacific, the North sea, Balkan sea and the Mediterranean sea realized the advantages of regionalism. They brought results such as controlling pollution in the North sea, an area encircled by industrialized states emitting chemical wastes into the sea, with the adoption of harmonized municipal laws. Another significant achievement was the prevention of oil-spills be legislating for double hulling of vessels. The Indian Ocean is surrounded by 28 states, which are categorized as "developing states in the Third world", with the only exception as Australia. These states acquired large resources of the sea with the adoption of UNCLOS III. But they are yet to identify the rights and obligations devolving on them and to realize that if they adhere to the new law, the management of the ocean affairs would ensure sustainable development and contribute to the war against poverty, which is the greatest challenge. This study has identified how these states could, particularly in regard to the prevention of marine pollution and managing living resources, a regional effort could achieve harmonization of laws and make a concerted effort to maintain scientific standard of management and avoid conflict.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Mellet, Bernice. "Ecological risk assessment of fisheries on sea turtles in the South Western Indian Ocean." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/9957.

Повний текст джерела

Анотація:

The SWIO is an area of great biodiversity and included in the diverse species that occupy the region are five species of sea turtles that include green turtles, hawksbills, leatherbacks, loggerheads and olive ridleys. Despite considerable conservation efforts at sea turtle rookeries in the South Western Indian Ocean, only green and loggerhead turtle populations have shown an increase in population size in recent years (<10 years), whereas leatherbacks remained stable and hawksbills and olive ridleys declined. This begs the question if fisheries (or other offshore pressures) are responsible for slowing the recovery of these populations in the region, and if so, which specific fisheries are responsible for this trend? Several offshore (mostly industrial) and coastal (mostly artisanal) fisheries overlap with sea turtle distribution at sea. Industrial fisheries that are globally known to have a demonstrable impact on sea turtle populations are longline and to a lesser extent purse seine fisheries, whilst prawn trawl, gillnet and beach seine fisheries are coastal fisheries with a known negative impact on sea turtle populations. Holistic conservation strategies should be developed that include both land and sea protection for sea turtle species. It is thus necessary to identify and manage offshore threats including fisheries activities, particularly those fisheries that are showing the highest risk to sea turtle populations. This prompted an investigation into the bycatch rates and mortality of all sea turtle species that occur in the SWIO region in several offshore and coastal fisheries including both industrial (longline, purse seine and prawn trawl) and artisanal (including gillnet and beach seine) fisheries. The specific aims were (i) to identify and quantify the interactions (and if possible mortality) of sea turtle species in fisheries and (ii) to identify vulnerable species/populations to fishing operations using a semi-quantitative Ecological Risk Assessment (ERA) in the form of a Productivity-Susceptibility Analysis (PSA). Published information, online databases and technical reports were used as data sources to establish a database containing essential information regarding fishing effort and sea turtle bycatch in the region. The existing information was used to map fisheries extent and effort within the region, and to perform bycatch calculations. Interactions and mortality rates for sea turtles in five fisheries were quantified using bycatch rates from regional studies. Between 2000 – 2011, industrial longline and purse seine fisheries captured sea turtles at a rate of 4 388 indiv.y-1, with the mortality rate being 189 indiv.y-1. The bulk of these interactions were in the longline industry that captured 4 129 ± 1 376 indiv.y-1, with a corresponding mortality rate of 167 ± 53 indiv.y-1. The most commonly caught species (in longlines) were loggerheads and leatherback turtles, but the greatest impact is expected to be on the leatherback population due to the high interaction rate relative to population size. The bycatch (259 ± 34 indiv.y-1) and mortality (20 ± 2 indiv.y-1) rates of sea turtles in the purse seine fishery was considerably lower than the longline fishery. The purse seine fishery thus does not seem to have a significant impact on sea turtle populations in the SWIO. The impact of all forms of fish aggregation devices were excluded from the analysis as the impacts of these are poorly documented. Coastal prawn trawl, gillnet and beach seine fisheries captured an estimate of between 50 164 - 52 370 indiv.y-1 from 2000-2011. The highest bycatch rate was estimated for gillnet fisheries (40 264 indiv.y-1) followed by beach seine fisheries (9 171 indiv.y-1) and prawn trawl fisheries (at 1089 – 2795 indiv.y-1). The gillnet fishery could be responsible for slowing the recovery rate of green turtle and leatherback populations in the SWIO due to the high capture rates in this fishery compared to the population sizes of the species. Beach seine and prawn trawl fisheries are not expected to be hamper the recovery rate of any of the populations in the SWIO due to the low levels of interactions and low mortality rates compared to the population sizes. There are however very few data available regarding the bycatch of sea turtle species within these fisheries, highlighting the need for further research regarding this. A productivity-Susceptibility Analysis (PSA) was used to evaluate the relative vulnerability of species to fisheries, and is frequently applied in data poor situations. Limited data on sea turtle life history characteristics and population dynamics of species in the SWIO prompted the use of a PSA to determine the species most vulnerable to fisheries in the region. Results of the PSA indicated that gillnet fisheries poses the largest fishery-related threat to sea turtle populations, specifically the green and leatherback populations. The longline fishery that poses a particular threat to the leatherback population in the SWIO is also a particular concern. A cumulative impact assessment (combining fisheries and other threats) indicated that the SWIO leatherback population is extremely vulnerable to the combination of threats that influence this population in the SWIO. Even though individual fisheries may pose a small threat, the cumulative impacts of the fisheries can lead to severe impacts on populations such as slowing the recovery rate of populations. There are however significant data gaps that require attention in order to fully assess the impact of these fisheries on sea turtle populations. Despite the fact that fisheries are not implicated as a mayor reason for the decline in the hawksbill and olive ridley populations in the region, these two species are in decline indicating that there are other factors responsible for the decline not yet identified. It however remains imperative to reduce the mortality from all sources to ensure the continued viability of sea turtle populations in the region.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Fenton, Mia. "Late Quaternary history of Red Sea outflow." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264851.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Hansingo, Kabumbwe. "Sea surface temperature anomalies in the South Indian ocean : observations and atmospheric modelling." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/4860.

Повний текст джерела

Анотація:

Bibliography: leaves 146-155.
Sea surface temperature (SSTs) variations in the South Indian Ocean have been found to influence rainfall over Southern Africa. As one of the modes of South Indian Ocean SST variability, the subtropical South Indian Ocean dipole is observed to be associated with dry and wet summer conditions over Southern Africa. The positive phase of the subtropical South Indian Ocean dipole is characterized by warm SST anomalies in the southwest South Indian Ocean and cool SST anomalies in the southeast. This phase is associated with above average summer rainfall over the subcontinent. The negative phase is associated with dry conditions over Southern Africa and is characterized by cool SST anomalies in the southwest and warm anomalies in the southeast South Indian Ocean. In order to investigate the atmospheric response over Southern Africa to this phenomenon, this study uses the MM5 regional climate model in which the model is forced with a warm pole SST anomaly south of Madagascar.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Keerawella, Gamini Bandara. "The growth of superpower naval rivalry in the Indian Ocean and Sri Lankan response." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28843.

Повний текст джерела

Анотація:

The Indian Ocean has experienced a process of profound change in its political and strategic map since World War II. This began with the British withdrawal from East of Suez, and was followed by the entry of the superpowers into the Indian Ocean, the growth of superpower naval rivalry, and the proliferation of security problems of the states in the region. The essence of these developments is the transformation of the Indian Ocean from the stability of one-power domination to the instability of superpower rivalry. The thesis examines the process of this transformation and the Sri Lankan response from a historical perspective. The transformation of the power structure in the Indian Ocean was essentially an outcome of the changes in power configurations in world politics. The growth of superpower rivalry in the Indian Ocean must be understood in relation to the evolution of political, economic, and strategic interests of the superpowers, advances in weapons systems and naval technology, and political developments in the region. The superpower naval rivalry has three interrelated elements, viz, naval deployments, weapons deals, and jockeying for bases/logistic support in the region. It evolves in three phases: from 1968 to the 1973 oil crisis; from the oil crisis to 1978; and since 1978. There are definite linkages between superpower naval rivalry and the conflict patterns in the region. The states in the region count on the superpowers for their security because of the inherent weaknessess of the ruling elites in the region, the limits of their security options, and economic dependence. The invariable outcome is a chain reaction resulting in military pacts, puppet governments, political supression, and proxy war, which forms the texture of the international politics of the Indian Ocean region. Sri Lankan responses to superpower naval rivalry can be explained in relation to the geo-political framework of her strategic thinking, and her internal political and economic processes. In the period 1948-56, Sri Lanka identified herself with the British defence structure in the Indian Ocean. With the changes introduced by the M.E.P. regime, non-alignment became the foreign policy approach of Sri Lanka after 1956. In accordance with the growth of superpower naval presence, Sri Lanka became more sensitive to Indian Ocean strategic issues in the 1960s. After 1970, Sri Lankan policy towards the Indian Ocean took a more coherent form and was designed to balance two considerations - first, at the sub-regional level, how to deal with India; and at the Indian Ocean level, how to check superpower naval rivalry and the increasing militarization of the Indian Ocean. This was reflected in Sri Lanka's proposal for an Indian Ocean Peace Zone (IOPZ). After 1977, under the changed internal and international situation, Sri Lanka soft-pedalled her earlier more articulated position regarding superpower naval riavlry in the Indian Ocean.
Arts, Faculty of
History, Department of
Graduate

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Senan, Retish. "Intraseasonal Variability Of The Equatorial Indian Ocean Circulation." Thesis, Indian Institute Of Science, 2004. https://etd.iisc.ac.in/handle/2005/297.

Повний текст джерела

Анотація:

Climatological winds over the equatorial Indian Ocean (EqlO) are westerly most of the year. Twice a year, in April-May ("spring") and October-December ("fall"), strong, sustained westerly winds generate eastward equatorial jets in the ocean. There are several unresolved issues related to the equatorial jets. They accelerate rapidly to speeds over lms"1 when westerly wind stress increases to about 0.7 dyne cm"2 in spring and fall, but decelerate while the wind stress continues to be westerly; each jet is followed by westward flow in the upper ocean lasting a month or longer. In addition to the semi-annual cycle, the equatorial winds and currents have strong in-traseasonal fluctuations. Observations show strong 30-60 day variability of zonal flow, and suggest that there might be variability with periods shorter than 20 days in the central EqlO. Observations from moored current meter arrays along 80.5°E south of Sri Lanka showed a distinct 15 day oscillation of equatorial meridional velocity (v) and off-equatorial zonal velocity (u). Recent observations from current meter moorings at the equator in the eastern EqlO show continuous 10-20 day, or biweekly, oscillations of v. The main motivation for the present study is to understand the dynamics of intraseasonal variability in the Indian Ocean that has been documented in the observational literature. What physical processes are responsible for the peculiar behavior of the equatorial jets? What are the relative roles of wind stress and large scale ocean dynamics? Does intraseasonal variability of wind stress force intraseasonal jets? What is the structure and origin of the biweekly variability? The intraseasonal and longer timescale variability of the equatorial Indian Ocean circulation is studied using an ocean general circulation model (OGCM) and recent in Abstract ii situ observations. The OGCM simulations are validated against other available observations. In this thesis, we document the space-time structure of the variability of equatorial Indian Ocean circulation, and attempt to find answers to some of the questions raised above. The main results are based on OGCM simulations forced by high frequency reanalysis and satellite scatterometer (QuikSCAT) winds. Several model experiments with idealized winds are used to interpret the results of the simulations. In addition to the OGCM simulations, the origin of observed intraseasonal anomalies of sea surface temperature (SST) in the eastern EqlO and Bay of Bengal, and related air-sea interaction, are investigated using validated satellite data. The main findings of the thesis can be summarized as: • High frequency accurate winds are required for accurate simulation of equatorial Indian Ocean currents, which have strong variability on intraseasonal to interannual time scales. • The variability in the equatorial waveguide is mainly driven by variability of the winds; there is some intraseasonal variability near the western boundary and in the equatorial waveguide due to dynamic instability of seasonal "mean" flows. • The fall equatorial jet is generally stronger and longer lived than the spring jet; the fall jet is modulated on intraseasonal time scales. Westerly wind bursts can drive strong intraseasonal equatorial jets in the eastern EqlO during the summer monsoon. • Eastward equatorial jets create a westward zonal pressure gradient force by raising sea level, and deepening the thermocline, in the east relative to the west. The zonal pressure force relaxes via Rossby wave radiation from the eastern boundary. • The zonal pressure force exerts strong control on the evolution of zonal flow; the decel eration of the eastward jets, and the subsequent westward flow in the upper ocean in the presence of westerly wind stress, is due to the zonal pressure force. • Neither westward currents in the upper ocean nor subsurface eastward flow (the ob served spring and summer "undercurrent") requires easterly winds; they can be gener ated by equatorial adjustment due to Kelvin (Rossby) waves generated at the western (eastern) boundary. • The biweekly variability in the EqlO is associated with forced mixed Rossby-gravity (MRG) waves generated by intraseasonal variability of winds. The biweekly MRG wave in has westward and upward phase propagation, zonal wavelength of 3000-4500 km and phase speed of 4 m s"1; it is associated with deep off equatorial upwelling/downwelling. Intraseasonal SST anomalies are forced mainly by net heat flux anomalies in the central and eastern EqlO; the large northward propagating SST anomalies in summer in the Bay of Bengal are due to net heat flux anomalies associated with the monsoon active-break cycle. Coherent variability in the atmosphere and ocean suggests air-sea interaction.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Senan, Retish. "Intraseasonal Variability Of The Equatorial Indian Ocean Circulation." Thesis, Indian Institute Of Science, 2004. http://hdl.handle.net/2005/297.

Повний текст джерела

Анотація:

Climatological winds over the equatorial Indian Ocean (EqlO) are westerly most of the year. Twice a year, in April-May ("spring") and October-December ("fall"), strong, sustained westerly winds generate eastward equatorial jets in the ocean. There are several unresolved issues related to the equatorial jets. They accelerate rapidly to speeds over lms"1 when westerly wind stress increases to about 0.7 dyne cm"2 in spring and fall, but decelerate while the wind stress continues to be westerly; each jet is followed by westward flow in the upper ocean lasting a month or longer. In addition to the semi-annual cycle, the equatorial winds and currents have strong in-traseasonal fluctuations. Observations show strong 30-60 day variability of zonal flow, and suggest that there might be variability with periods shorter than 20 days in the central EqlO. Observations from moored current meter arrays along 80.5°E south of Sri Lanka showed a distinct 15 day oscillation of equatorial meridional velocity (v) and off-equatorial zonal velocity (u). Recent observations from current meter moorings at the equator in the eastern EqlO show continuous 10-20 day, or biweekly, oscillations of v. The main motivation for the present study is to understand the dynamics of intraseasonal variability in the Indian Ocean that has been documented in the observational literature. What physical processes are responsible for the peculiar behavior of the equatorial jets? What are the relative roles of wind stress and large scale ocean dynamics? Does intraseasonal variability of wind stress force intraseasonal jets? What is the structure and origin of the biweekly variability? The intraseasonal and longer timescale variability of the equatorial Indian Ocean circulation is studied using an ocean general circulation model (OGCM) and recent in Abstract ii situ observations. The OGCM simulations are validated against other available observations. In this thesis, we document the space-time structure of the variability of equatorial Indian Ocean circulation, and attempt to find answers to some of the questions raised above. The main results are based on OGCM simulations forced by high frequency reanalysis and satellite scatterometer (QuikSCAT) winds. Several model experiments with idealized winds are used to interpret the results of the simulations. In addition to the OGCM simulations, the origin of observed intraseasonal anomalies of sea surface temperature (SST) in the eastern EqlO and Bay of Bengal, and related air-sea interaction, are investigated using validated satellite data. The main findings of the thesis can be summarized as: • High frequency accurate winds are required for accurate simulation of equatorial Indian Ocean currents, which have strong variability on intraseasonal to interannual time scales. • The variability in the equatorial waveguide is mainly driven by variability of the winds; there is some intraseasonal variability near the western boundary and in the equatorial waveguide due to dynamic instability of seasonal "mean" flows. • The fall equatorial jet is generally stronger and longer lived than the spring jet; the fall jet is modulated on intraseasonal time scales. Westerly wind bursts can drive strong intraseasonal equatorial jets in the eastern EqlO during the summer monsoon. • Eastward equatorial jets create a westward zonal pressure gradient force by raising sea level, and deepening the thermocline, in the east relative to the west. The zonal pressure force relaxes via Rossby wave radiation from the eastern boundary. • The zonal pressure force exerts strong control on the evolution of zonal flow; the decel eration of the eastward jets, and the subsequent westward flow in the upper ocean in the presence of westerly wind stress, is due to the zonal pressure force. • Neither westward currents in the upper ocean nor subsurface eastward flow (the ob served spring and summer "undercurrent") requires easterly winds; they can be gener ated by equatorial adjustment due to Kelvin (Rossby) waves generated at the western (eastern) boundary. • The biweekly variability in the EqlO is associated with forced mixed Rossby-gravity (MRG) waves generated by intraseasonal variability of winds. The biweekly MRG wave in has westward and upward phase propagation, zonal wavelength of 3000-4500 km and phase speed of 4 m s"1; it is associated with deep off equatorial upwelling/downwelling. Intraseasonal SST anomalies are forced mainly by net heat flux anomalies in the central and eastern EqlO; the large northward propagating SST anomalies in summer in the Bay of Bengal are due to net heat flux anomalies associated with the monsoon active-break cycle. Coherent variability in the atmosphere and ocean suggests air-sea interaction.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Wachenfeld, David R. "Aspects of the behaviour and ecology of Red Sea and Indian Ocean triggerfishes (Balistidae)." Thesis, University of York, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359305.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Hamilton, Brett Russell. "Analysis and characterisation of ciguatoxins present in fish of the Indian Ocean, the Pacific Ocean, and the Caribbean Sea /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17143.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Preston, Anthony. "Southern African rainfall variability and Indian Ocean sea surface temperatures : an observational and modelling study." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411052.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Eriksson, Hampus. "Managing sea cucumber fisheries and aquaculture : Studies of social-ecological systems in the Western Indian Ocean." Doctoral thesis, Stockholms universitet, Systemekologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75515.

Повний текст джерела

Анотація:

Collecting sea cucumbers to supply the high value Chinese dried seafood market is a livelihood activity available to many people in the Western Indian Ocean (WIO), making it an important part of local economies. These fisheries are generally not successfully managed and tropical sea cucumber fisheries show continuing signs of decline. This thesis takes a social-ecological systems approach to guide better management of sea cucumber fisheries and aquaculture in the WIO. Papers 1 and 2 analyse the fishery situation in Zanzibar and find that in the absence of effective management institutions and income alternatives among fishers, leading to dependence, there are unsustainable expanding processes. Paper 3 compares the unmanaged fishery in Zanzibar to the highly controlled situation in Mayotte. In Mayotte, a protection effect is evident and the commercial value of stocks is significantly higher than in Zanzibar. The analysis of the situation in Mayotte demonstrates the importance of matching the fishery – management temporal scales through prepared and adaptive management to avoid processes that reinforce unsustainable expansion. Paper 4 analyses sea cucumber community spatial distribution patterns at a coastal seascape-scale in Mayotte establishing baseline patterns of habitat utilization and abundance, which can be used as reference in management. Paper 5 reviews the potential for sea cucumber aquaculture in the WIO. The review illustrates that this activity, which is currently gaining momentum, does so based on inflated promises and with significant social-ecological risks. Emphasis for improvements is, in this thesis, placed on the importance of prepared and adaptive institutions to govern and control expanding processes of the fishery. These institutional features may be achieved by increasing the level of knowledge and participation in governance and by integration of sea cucumber resources management into higher-level policy initiatives.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

CARAGNANO, ANNALISA. "Lithopyllum spp. as proxy of climate variability in the nw indian ocean." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41553.

Повний текст джерела

Анотація:

A previously unexplored subfamily of coralline algae, the Lithophylloideae, was investigated as potential paleoclimatic archive. For the first time, seasonal changes in Mg/Ca, Li/Ca and Ba/Ca composition of Lithophyllum spp. from the Gulf of Aden (Balhaf, Yemen), the Arabian Sea (Socotra, Yemen), and the South of Red Sea (Kamaran, Yemen) were investigated by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For the first time in coralline algae, the Li/Ca composition was analyzed and showed a highly significant and positive correlation with Mg/Ca and SST. Monthly algal Mg/Ca and Li/Ca variations indicate a positive correlation with sea water temperature (SST). Although no correlation between monthly algal Ba/Ca and local (SST) was found, fluctuations in Ba/Ca indicate the influence of nutrients introduced by seasonal upwelling, and record an increase of sediment at the sampling sites. From the age model of Mg/Ca the annual algal extension rates were measured in all specimens of Lithophyllum spp., and they resulted highly variable, mainly influenced by light and occasional burial. The elementary ratio of Mg/Ca, Li/Ca and Ba/Ca, and annual extension rate were successfully used in historical reconstruction of the climate and oceanographic variability of the study area.

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Berry, Amanda Susan. "Solid-state speciation and sea-water solubility studies and trace metal chemistry of the Indian Ocean aerosol." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314539.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Le, Blanc Jean-Luc. "The role of the Indian Ocean in the global climate system : the propagation of Indian Ocean Kelvin waves in the Indonesian Seas and their influence on western Pacific sea level variability." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402544.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Mathew, Johan. "Margins of the Market: Trafficking and the Framing of Free Trade in the Arabian Sea, 1870s to 1960s." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10535.

Повний текст джерела

Анотація:

My dissertation traces how the interplay of trafficking and regulation shaped free trade in the Arabian Sea. It explores trafficking in the littoral region stretching from western India to the Swahili Coast, as it evolved under colonial regulation. British officials wanted commercial practices in the Arabian Sea to conform to their perception of free trade, but their dedication to laissez-faire policies prevented them from intervening directly in trade. But smuggling provided the perfect justification for intervention. Colonial regulation focused on four illicit arenas that structured free trade: labor, security, finance and transportation. The suppression of the slave trade would produce wage labor. The suppression of the arms traffic would eliminate violence from trade. The regulation of currency arbitrage would create a stable monetary standard. Finally, the regulation of shipping would develop a transportation system which could incorporate distance into the calculation of price. Yet these regulatory efforts were frustrated by merchant networks which exploited the gaps in the enforcement of these regulations. Merchants co-opted regulators, circumvented regulations and evaded policing in order to structure transactions to their own advantage. Thus my dissertation demonstrates how free trade in the Arabian Sea was framed through this intricate interplay of trafficking and regulation.
History

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Wall-Palmer, Deborah. "Response of pteropod and related faunas to climate change and ocean acidification." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1398.

Повний текст джерела

Анотація:

Recent concern over the effects of ocean acidification upon calcifying organisms in the modern ocean has highlighted the aragonitic shelled thecosomatous pteropods as being at a high risk. Laboratory studies have shown that increased pCO2, leading to decreased pH and low carbonate concentrations, has a negative impact on the ability of pteropods to calcify and maintain their shells. This study presents the micropalaeontological analysis of marine cores from the Caribbean Sea, Mediterranean Sea and Indian Ocean. Pteropods, heteropods and planktic foraminifera were picked from samples to provide palaeoenvironmental data for each core. Determination of pteropod calcification was made using the Limacina Dissolution Index (LDX) and the average shell size of Limacina inflata specimens. Pteropod calcification indices were compared to global ice volume and Vostok atmospheric CO2 concentrations to determine any associations between climate and calcification. Results show that changes in surface ocean carbonate concentrations throughout the Late Pleistocene did affect the calcification of thecosomatous pteropods. These effects can be detected in shells from marine sediments that are located well above the aragonite lysocline and have not undergone post-depositional dissolution. The results of this study confirm the findings of laboratory studies, showing a decrease in calcification during interglacial periods, when surface ocean carbonate concentrations were lower. During glacial periods, calcification was enhanced due to the increased availability of carbonate. This trend was found in all sediments studied, indicating that the response of pteropods to past climate change is of global significance. These results demonstrate that pteropods have been negatively affected by oceanic pH levels relatively higher and changing at a lesser rate than those predicted for the 21st Century. Results also establish the use of pteropods and heteropods in reconstructing surface ocean conditions. The LDX is a fast and appropriate way of determining variations in surface water carbonate saturation. Abundances of key species were also found to constrain palaeotemperatures better than planktic foraminifera, a use which could be further developed.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Mihut, Dona. "Breakup and mesozoic seafloor spreading between the Australian and Indian plates." Phd thesis, Department of Geology and Geophysics, 1997. http://hdl.handle.net/2123/8940.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Yu, Zhaojie. "Quaternary Indian and East Asian monsoon reconstructions and their impacts on weathering and sediment transport to the ocean." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS189.

Повний текст джерела

Анотація:

L'objectif principal de cette thèse est de restituer l'évolution passée des moussons asiatiques au cours du Quaternaire et d’en évaluer leurs impacts sur l’érosion continentale et les transferts sédimentaires terre-mer, à partir de l’étude de carottes marines collectées dans la Baie du Bengale, l'ouest de la mer des Philippines et la mer d'Arabie. La stratégie scientifique mise en œuvre implique des analyses minéralogiques (argiles), sédimentologiques (granulométrie laser) et géochimiques (⁸⁷Sr/⁸⁶Sr et εNd) afin de restituer les zones sources sédimentaires, les conditions d’érosion et de transfert sédimentaires à l’océan. Les analyses de la concentration en élément des terres rares et des valeurs de l’εNd ont également été faites sur des échantillons d’eau de mer et de foraminifères collectés dans la Baie du Bengale afin de contraindre l’utilisation de ce traceur dans un contexte de très forts changements saisonniers de débit des fleuves Himalayens. Cette stratégie nous a permis, entre autre, de restituer les précipitations de mousson du domaine ouest tropical Pacific au cours du Quaternaire et d’établir un lien avec l’évolution à long terme de la dynamique de circulation méridienne de type ENSO. Nous avons également apporté de nouvelles contraintes sur l’utilisation du traceur εNd dans les foraminifères de la Baie du Bengale en vue d’en restituer la dynamique passée de l’érosion himalayenne
The main objective of this PhD study is to reconstruct the evolution of the Asian monsoons during the Quaternary and their impacts on the continental erosion and sedimentary transfers from land to sea by the investigation of sediments cores collected in the Northern Bay of Bengal, the western Philippines Sea and the Arabian Sea. The implemented scientific strategy involves mineralogical (clay size fraction), sedimentological (grain-size laser) and geochemical (⁸⁷Sr/⁸⁶Sr and εNd) analyses in order to establish sedimentary sources, conditions of erosion and transfer of sediments to the Ocean. The analyses of the concentration of Rare Earth Elements (REE) and εNd were also made on seawater and foraminifera samples to better constrain the εNd as a proxy of weathering in a context of strong seasonal variations of sediment discharges by Himalayan rivers. Clay mineralogy and laser grain-size analyses have been conducted on sediments from core MD06-3050 collected on the Benham Rise (Philippines Sea). Siliciclastic grain-size results indicate variations of the relative proportion of three grain-size sub-populations corresponding to eolian dusts (EM2 about 9-11 μm) and Luzon rivers inputs (EM1 about 2-5 μm and EM3 about 19-25 μm). The long-term evolutions of the EM1/EM2 and smectite/(illite+chlorite) ratios permit to reconstruct variations of the contribution of detrital material deriving from the volcanic arc of Luzon and rainfall intensity of this tropical region. At long time scale, periods of intensification of monsoon rainfall on Luzon are associated to a reduction of precipitation on central China. These periods are also associated to an increase of the zonal gradient of sea surface temperatures on the equatorial Pacific Ocean suggesting a strengthening of El Niña conditions. These results highlight for the first time a strong role of the dynamics of the meridian circulation of ENSO on the long-term changes of rainfall of the tropical western Pacific during the Quaternary. In the Arabian Sea, clay mineralogy, siliciclastic grain-size, ⁸⁷Sr/⁸⁶Sr ratio and εNd were analysed on Quaternary sediments of the IODP site U1457. Our results suggest a change in the relative proportions of sediments from the Deccan Trapps (smectite) and the Indus river (mainly illite and chlorite). Variability of sedimentary sources and sediment transport (turbidites activity) to the Indus Fan have been reconstructed and attributed to monsoon rainfall and the sea level variations. The concentrations of REE combined with εNd were analysed on seawater samples collected in June 2012 along a North-South cross section in the Bay of Bengal. We highlighted from normalized REE patterns that the contributions of dissolved REE from the Ganges-Brahmaputra river system was the main source of the dissolved REE of surface waters of the Bay of Bengal, whereas the desorption of lithogenic particles dominate the dissolved REE of the intermediate and deep waters masses. We then revalued the residence time of the dissolved REE in the Bay of Bengal. A comparison of εNd, obtained just before the increase of the Ganges-Brahmaputra river discharge inferred by Indian monsoon rainfall, with the results obtained by Singh and al. (2012) for seawater samples collected after the peak of river discharge, allowed us to highlight for the first time a seasonal variability of seawater εNd of the Bay of Bengal. εNd have been analysed on planktonic foraminiferas of core MD77-176 located at 1375 m water depth to reconstruct for the first time the seawater εNd record of the intermediate waters masses of northern Bay of Bengal for the last 27 kyr. This new seawater εNd record of the Northern Bay of Bengal give us new constrain for this proxy already used to reconstruct past changes of the Himalayan weathering

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Amollo, Joseph Odhiambo. "Aspects of sea level variability in the southwest Indian Ocean and the east coast of Africa - (latitude 0-35°S and from the coast to 60°E)." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/14100.

Повний текст джерела

Анотація:

Analysis of tide gauge sea level observations of varying durations in the southwest Indian Ocean and the East coast of Africa (Lamu, Mombasa, Zanzibar, Durban, Port La Rue and Port Louis) show variability which are related to global, regional time scales, local weather and climatic changes, oceanographic and hydrological forcing that manifest in both short and long time scales. The investigations on the tide gauge sea level observations are conducted through the separation of the total sea level measurements into the contributing components (tides and residuals) using a Matlab in built software (t-tide). Short time scale sea level variability in the southwest Indian Ocean is due to the effects of tides which exhibit tidal range variations with latitude and shelf width, storm surges resulting from tropical cyclones passage especially in the mid-latitude region, atmospheric pressure fluctuations over the surface of the sea and local wind fields. Sea surface temperature variations during summer and winter result in differential heating of the ocean surface and contribute to the observed sea level variability at seasonal time scale especially in the region 25°S and southwards where the temperature differences are large. The equatorial region is characterized by a near constant sea surface temperature that sustains thermal expansion of the upper layer of the ocean water throughout the year. Monsoon periods show significant and variable wind speeds that impact on sea level variability in the southwest Indian Ocean and the East coast of Africa and are greatest during the summer monsoon (from June to August). On longer time scales (Interannual and decadal), sea level variations in this region is mostly influenced by the El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). During the 1997/98 El Nino event, the sea levels are significantly higher than normal at the coast and the islands. During the 2000/2001 La Nina, the sea levels are significantly lower than normal at the coasts in the southwest Indian Ocean. Indian Ocean Dipole effects are significant in the southwest Indian Ocean during the period 2006 through to 2008 and are more enhanced in 2007. The annual highest sea levels in this region are influenced by the year to year changes in weather pattern and the perigean cycle of the tides on a 4.4 year period but their secular trends are not statistically significant.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Ranasinghage, Pradeep Nalaka. "Holocene Coastal Development in Southeastern-Eastern Sri Lanka: Paleo-Depositional Environments and Paleo-coastal Hazards." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1286816740.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Regenberg, Anke [Verfasser]. "Climate variability in the Eastern Indian Ocean during marine isotope stage 3 : high-resolution proxy studies from the Timor Sea / Anke Dürkop." Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1019982810/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Catry, Thibault. "Magma injections and destabilization of basaltic volcanoes : A numerical study : Application to La Reunion (Indian ocean, France) and Stromboli (Tyrrhenian sea, Italy)." Phd thesis, Université de la Réunion, 2011. http://tel.archives-ouvertes.fr/tel-00805509.

Повний текст джерела

Анотація:

Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Catry, Thibault <1985&gt. "Magma injections and destabilization of basaltic volcanoes: a numerical study. Application to La Reunion (Indian ocean, France) and Stromboli (Tyrrhenian sea, Italy)." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3904/1/thibault_catry_tesi.pdf.

Повний текст джерела

Анотація:

Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Catry, Thibault <1985&gt. "Magma injections and destabilization of basaltic volcanoes: a numerical study. Application to La Reunion (Indian ocean, France) and Stromboli (Tyrrhenian sea, Italy)." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3904/.

Повний текст джерела

Анотація:

Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

King, Nicola Jane. "Deep-sea demersal ichthyofauna of contrasting localities - Mid-Atlantic Ridge, Nazaré Canyon (North Atlantic Ocean) and Crozet Plateau (Southern Indian Ocean) - with special references to the abyssal grenadier, Coryphaenoides (Nematonurus) armatus (Hector, 1875)." Thesis, University of Aberdeen, 2006. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602325.

Повний текст джерела

Анотація:

The first observations of deep-demersal scavenging fishes are presented from three regions of the world’s oceans with contrasting overlying productivity: the Mid-Atlantic Ridge (MAR) and Nazaré Canyon, Northeast Atlantic Ocean, and the Crozet Plateau, Southern Indian Ocean. The MAR is the most significant topographic feature of the North Atlantic Ocean and is under the influence of a sub-polar front with increased productivity to the north. Twenty-two taxa were photographed at bait; 14 at 42°N and 17 over two transects at 51 and 53°N respectively. Decreases in biodiversity across the 51°N transect compared to the 42 and 53°N transects, support the hypothesis that 48°N - 52°N is a region of faunal change in demersal fish assemblages in the North Atlantic Ocean. The Nazaré Canyon is a large submarine canyon intersecting the Iberian continental margin which received high levels of organic matter from local upwelling and terrigenous sources. Nine fish species were photographed at the baited ROBIO lander at all depths within the canyon. It is hypothesised that the increased organic input positively influences benthic food supply within the canyon, supporting elevated populations of scavenging fauna. The Crozet Plateau is situated in the southern reaches of the Indian Ocean, where the abyssal seafloor (ca. 4200 m) received differing levels of surface-derived organic enrichment. Demersal ichthyofaunal biodiversity, abundance and biomass were sampled by a trawl at a eutrophic site (M5) and oligotrophic site (M6). Demersal fish species richness, abundance and biomass were greater at M5 compared to M6, and dominated by Macrouridae. However, overall results were not significant, leading to the conclusion that the rattail fishes are transient between sites. Six species new to science were collected and are described herein (one Ophidiid, three Liparidae and two Zoarcidae), as well as several other rare specimens of Ophidiid and Zoarcid.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Thomas, Alexander Llewellyn. "Variations in past and present ocean circulation assessed with U-series nuclides." Thesis, University of Oxford, 2006. http://ora.ox.ac.uk/objects/uuid:31d15cab-d817-438b-bba0-551921704fa7.

Повний текст джерела

Анотація:

This thesis considers the use of two U-series nuclides – 231 Pa and 230 Th – as proxies for studying ocean circulation. A total of six water-column profiles of 231 Pa, 230 Th, and 232 Th have been measured from two regions of the southwestern Indian Ocean: the Madagascar and Mascarene Basins; and the southeastern continental margin of South Africa. Measurement by MC-ICP-MS of 10 litre water samples is possible for samples with as little as 4 and 2 fg of 231 Pa and 230 Th and yields typical uncertainties of 6% and 14% respectively. These profiles show that the scavenging and advection histories of water masses can affect their 231 Pa concentration, with distinct variations superimposed on a general increase in concentration with depth due to reversible scavenging. A 1D particle scavenging model is used to show that sedimentary (231 Paxs /230 Thxs )0 is most representative of the (231 Pa/230 Th) of the bottom most water mass at any one locality, although in turn this water mass (231 Pa/230 Th) will be dependent not only on its advection and scavenging history but also the 231 Pa and 230 Th concentrations of the overlying water masses during advection. Acknowledgment that sedimentary (231 Paxs /230 Thxs )0 is “set” by the bottommost water mass is important for interpretation of scenarios where changes in depth of circulation, as well as circulation strength, may have occurred. A record of sedimentary (231 Paxs /230 Thxs )0 has been recovered from a 6 m Kasten core from the Mascarene Basin covering the past 140 ka, in order to reconstruct flow of AABW into the basin. The (231 Paxs /230 Thxs )0 measured is below the production ration of 0.093 and shows no significant variation. This indicates that (231 Paxs /230 Thxs )0 is sensitive to changes in particle productivity and circulation at this location and that there has been little or no change in either environmental variable over the last full interglacial-glacial cycle. This finding is in contrast to other ocean basins, particularly the North Atlantic, where large changes in circulation are observed.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Yoon, Hong-Joo. "La variation du niveau de la mer sur la région d'Amsterdam-Gozet-Kerguelen au sud de l'océan indien." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10092.

Повний текст джерела

Анотація:

L'objectif de cette these est d'ameliorer la connaissance des variations du niveau de la mer et des circulations oceaniques dans cette region, il s'agit d'observer et de comprendre les variations du niveau de la mer, de valider les mesures d'altimetrie satellitaire (topex/poseidon et ers 1) et de determiner les transports au cca. Ce travail a ete mene en particulier dans le cadre du reseau international gloss (global sea level system) pour la surveillance de l'evolution a long terme du niveau de la mer, et dans le cadre du projet international woce (world ocean circulation experiment), incluant la mission satellitaire franco-americaine de topex/poseidon. Cette etude a permis des informations sur le niveau de la mer et la circulation generale dans cette region : le niveau de la mer moyen sur tout le domaine donne une pente negative de 2 mm/an entre 1993 et 1995 et il y a l'existence d'un meandre permanent le long du front subtropical dans le courant circumpolaire antarctique.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Urvois, Marc. "Apports de l'estimation geostatistique de l'epaisseur des unites metalliferes dans la comprehension des mecanismes de mise en place des sediments de la fosse atlantis ii (mer rouge)." Orléans, 1987. http://www.theses.fr/1987ORLE2049.

Повний текст джерела

Анотація:

Cette approche geostatistique menee sur les deux niveaux sulfures (su::(1) et su::(2)) et sur le niveau oxyde (co) montre que la repartition n'est pas aleatoire. L'analyse comparative des cartes isopaques met en evidence des similitudes entre su::(2) et co et une distribution distincte entre su::(1) et su::(2), indiquant par la que la repartition des sediments est independante des conditions d'oxydo-reduction du milieu. Les teneurs en elements de base (zn, cu, fe, mn, s sulfure) sont etudiees a travers leur moyenne ponderee, par unite lithologique et par bassin. Elles montrent une migration des sources dans l'espace et le temps depuis le nord de la fosse lors du depot de su::(1), vers le sud pendant celui de su::(2). Les teneurs en elements chalcophiles dans le bassin sud-ouest, region actuelle des emergences, sont systematiquement superieures a celles du reste de la fosse. Le developpement d'un panache en milieu oxygene conduit a la precipitation preponderante d'oxydes et a la formation du niveau oxyde (co). A l'inverse, des episodes moins intenses correspondent au piegeage du fluide hydrothermal dans les saumures et au depot des niveaux sulfures (su::(1) et su::(2))

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Sjöberg, Niklas B. "Eel migration - results from tagging studies with relevance to management." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-113829.

Повний текст джерела

Анотація:

In response to the drastic decline of the European eel (Anguilla anguilla (L.)) fisheries have been reduced and elvers are stocked in areas where natural abundances are low. Are these measures adequate? To answer different aspects of this question, we have analysed more than a century of eel tagging, using both traditional and more novel capture – recapture analyses. Based on these long-term data, we have evaluated the impact of the Swedish eel coastal fisheries using Survival analysis. Our analysis indicates that the fishing mortality just prior the 2009 fishing restrictions were in the order of 10%. More recent tagging programs have focused on issues related to the fate of stocked fish. If and how they migrate out of the Baltic Sea and further on towards the Atlantic Ocean. Both earlier and our new studies reveal that all eels recaptured on the Swedish East Coast, no matter of their origin, migrate at a reasonable speed and direction towards the outlets of the Baltic Sea. Even though it is sometimes difficult to determine their origin, our analyses indicate that stocked fish were scarce among the recaptures. In an experiment on the Swedish West Coast, we knew the individuals’ origin (stocked or wild) and they had similar migration patterns. In contrast, silver eel in Lake Mälaren – assumed to have been stocked as elvers or bootlace eels – seemed to have difficulties in finding the outlets. Instead they overwintered and lost weight. However, weight losses are also significant among non-stocked individuals in the Baltic Sea, both if they overwinter and if they appear to be on their way out from the area. It remains an open question whether eels from the Baltic region in general, and whether the overwintered fish in particular, manage to reach the spawning area in the Atlantic Ocean. Based on current knowledge, I advocate invoking the precautionary approach and to concentrate Swedish eel stockings to the West Coast and allow the young fish to spread out on their own.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Abou, Karaki Najib. "Synthese et carte sismotectonique des pays de la bordure orientale de la mediterranee : sismicite du systeme de failles du jourdain-mer morte." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13067.

Повний текст джерела

Анотація:

Realisation d'une carte sismotectonique (echelle 1:1 000 000) fondee sur la sismicite historique et instrumentale, la tectonique active, le volcanisme et les aspects geophysiques. Cette carte, concue sur support numerique, est evolutive et modifiable en temps reel. Les premiers mecanismes focaux de la zone du golfe d'aquaba et des failles du carmel sont proposes, accompagnes des relocalisations des trois crises recentes dans cette zone. Une distribution epicentrale en anneau de sismicite est mise en evidence dans la partie centrale de la vallee du jourdain. Les taux de recurrence pour les segments de la faille du jourdain sont calcules. On met l'accent sur les erreurs chronologiques, de localisation et d'interpretation de la sismicite

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Kotarba-Morley, Anna Maria. "The Port of Berenike Troglodytica on the Red Sea : a landscape-based approach to the study of its harbour and its role in Indo-Mediterranean trade." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:dc80167b-8b1e-499d-9b7c-038e10b2e782.

Повний текст джерела

Анотація:

The port site of Berenike Troglodytica - located on the Egyptian Red Sea coast - served the spice and incense routes that linked the Mediterranean World (specifically the Roman Empire) to India, Southern Arabia and East Africa. In the Greco-Roman period the site was at the cutting edge of what was then the embryonic global economy, ideally situated as a key node connecting Indian Ocean and Mediterranean trade for almost 800 years. It is now located in an arid, marginal, hostile environment but the situation must have been very different 2300 years ago, at the time of its founding. At the time of elephant-hunting trips during the Hellenistic period before the inception of its important role in the global markets of the day in the Roman period Berenike would have to have looked much different to what we can now imagine. What was it like then, when the first prospectors visited this location at the time of Ptolemy II? Why this particular place, and this particular landscape setting seemed such a propitious location for the siting of an important new harbour? Given the importance of the port over almost a millennium it is perhaps surprising that very little is known about the different factors impacting on the foundation, evolution, heyday and subsequent decline of the city; or the size, shape, and capacity of its harbour. The intention of this research is to address this shortfall in our knowledge, to examine the drivers behind the rise and fall of this port city, and to explore the extent to which the dynamics of the physical landscape were integral to this story. Using an innovative Earth Science approach, changes in the archaeological 'coastscape' have been reconstructed and correlated with periods of occupation and abandonment of the port, shedding light on the nature, degree and directionality of human-environment interactions at the site. This work has revealed profound changes in the configuration of the coastal landscape and environment (including the sea level) during the lifespan of Berenike, highlighting the ability of people to exploit changes in their immediate environment, and demonstrating that, ultimately, the decline of the port was partly due to these landscape dynamics. To further explore these themes the landscape reconstructions have been supplemented by semi-quantitative analyses of a suite of variables likely to influence the initial siting of new ports of trade. These have shown that although the site of Berenike was ideal in terms of its coastal landscape potential, possessing a natural sheltered bay and lagoon system, the choice of location was not solely influenced by its environmental conditions. Additionally, a detailed review of vessels that plied Red Sea and Indian Ocean routes is presented here in order to better understand the design and functioning of Berenike's harbour. This serves the purpose of identifying unifying features that provide more detail about the size and draught of vessels and the potential capacity of the harbour basin. By using this multi-scalar approach it has been possible to reconstruct the 'coastscape' of the site through the key periods of its occupancy and those phases immediately before and after its operation. This has wide-ranging implications for researchers studying ancient ports along this trade network as a larger database will tease out more details about how influential the landscape was in the initial siting of the port and its subsequent use and decline.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Bouffaut, Léa. "Detection and classification in passive acoustic contexts : application to blue whale low-frequency signals Passive stochastic matched filter for Antarctic blue whale call detection, in The Journal of the Acoustical Society of America 144 (2), 2018 Baleen whale distribution and seasonal occurrence revealed by an ocean bottom seismometer network in the Western Indian Ocean, in Deep Sea Research Part II: Topical Studies in Oceanography 161, March 2019." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0057.

Повний текст джерела

Анотація:

L’analyse des grands volumes de données générés par la surveillance par acoustique passive long-terme et continue des baleines bleues (BW) est améliorée par la détection automatisée des signaux d’intérêt. Le travail présenté dans cette thèse s’attaque au problème de la détection et classification de signaux stéréotypés dans un contexte passif basse fréquence où les signaux sont modifiés par le canal de propagation, bruités et où le SNR varie continuellement. Les méthodes développées sont appliquées à des enregistrements issus d’OBS déployés dans l'océan Indien occidental.Premièrement, le filtrage adapté stochastique (SMF) est étendu au contexte passif en adaptant l’estimation du bruit et du SNR. Ce filtre est appliqué avec succès pour la détection des calls de baleine bleue antarctique et est comparé aux MF et Z-detector sur données annotées présentant de nombreux bruits et d’importantes variations du SNR. Les excellentes performances du SMF passif permettent d’augmenter la portée de détection jusqu'à 100 km en présence de bruit de bateau.La détection simultanée de différentes espèces s’appuie sur un schéma de reconnaissance de formes où les signaux tonaux de BW sont extraits, caractérisés et classifiés pour la transcription automatique des chants.Les signaux ainsi identifiés sont ensuite reconstruits avec des formes d'onde distinctes reproduisant les chants sous-jacents. Le succès de la reconstruction repose sur la qualité de la détection de tonales: le détecteur de crêtes est choisi pour son efficacité. Les résultats d'apprentissage et la première application non supervisée de la transcription ont révélé des résultats prometteurs et son utilité pour l’analyse multi-espèces
The analysis of the large volumes of data resulting from continuous and long-term monitoring efforts of blue whales (BWs) benefits from the automated detection of target signals. This thesis investigates the challenging problem of the detection and classification of stereotyped signals in a low-frequency passive acoustic context where (1) signals traveling long distances are deteriorated by the propagation channel, (2) overlapping noises interfere and, (3) SNRs vary continuously. Developed methods are applied to recordings from ocean bottom seismometers deployed in the western Indian Ocean.First, the stochastic matched filter (SMF) is adapted to the passive context by overcoming noise estimation and estimating the SNR automatically. This filter is successfully applied to the detection of Antarctic blue whales calls and is compared to the MF and the Z-detector on an annotated ground-truth dataset exhibiting various SNRs and noises. The passive SMF showed better performances, increasing the detection range up to 100 km in the presence of ship noise.The problematic of the detection of concurrently calling species is addressed based on a pattern recognition development for the automatic transcription of BW songs where, tonal signals are extracted, characterized, and classified. The hence identified signals are then reconstructed as separate waveforms reconstructing of the underlying songs. The success of the reconstruction relies on the quality of the tonal detector: the ridge detector was chosen for its efficiency. Training and unsupervised application revealed promising results of the proposed transcription method and its utility for multi-species analysis

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Omar, Youssouf Moussa. "Etude de l'habitat épipélagique du Golfe de Tadjourah (Djibouti) : structures de variabilité et processus qui les gouvernent." Thesis, Brest, 2016. http://www.theses.fr/2016BRES0017/document.

Повний текст джерела

Анотація:

L’objectif de cette thèse est d’étudier les caractéristiques physiques et biogéochimiques de l’habitat épipélagique (0-200 m), ses variabilités spatio-temporelles et les processus qui les gouvernent dans le Golfe de Tadjourah (Djibouti). L’analyse spectrale singulière (SSA) et la fonction empirique orthogonale (EOF) sont appliquées à deux jeux des données satellitales dérivées du radiomètre AVHRR_MetopA et des capteurs de la couleur de l’océan (Modis et Meris). Cette analyse statistique montre que les variabilités de la température de la surface de la mer (SST) et de la concentration de la chlorophylle a (CHLa) sont essentiellement expliquées par les cycles annuels et semi-annuels. Le cycle annuel de la SST montre l’alternance des eaux chaudes d’avril à octobre et des eaux froides de novembre à mars. Le cycle semi-annuel indique une légère baisse de la SST entre juillet et aout, particulièrement à l’ouest du golfe. Pour la CHLa, la variabilité est entièrement représentée par le cycle annuel. Celui-ci indique l’enrichissement des eaux du large avec un fort gradient côte-large de juillet à novembre et une tendance inverse de décembre à juin. En outre, l’analyse spectrale singulière multi-canal (M-SSA) et la fonction de corrélation croisée avec fenêtre de 120 jours, appliquées à l’ensemble des paramètres océanique (SST et CHLa) et atmosphériques (Vent, Température et humidité spécifique de l’air) révèlent que le cycle annuel de la SST est relié aux flux de chaleur à l’interface air-mer. En revanche, le refroidissement des eaux durant juillet-aout associé au pic de la CHLa, a été attribué au phénomène d’upwelling. Dans la seconde partie, afin d’élucider l’influence océanique sur la SST et la CHLa, les structures thermohalines and biogéochemiques de la couche supérieure (0-200 m) sont étudiées à l’aide des données collectées durant juillet-aout 2013, septembre 2013 et Février 2014. Les résultats montrent qu’en juillet-aout, la couche superficielle se composait d’une couche de mélange (CM) s’étendant sur environ 20-30 m de profondeur, suivie d’une thermocline localisée entre 30 and 50 m. La CM était réduite à l’ouest et au sud-est du golfe où le gradient thermique et la CHLa étaient plus élevées proche de la surface. En septembre, cette stratification persistait mais la CM était plus chaude et salée. En Février, la CM s’étendait sur environ 120 m de profondeur et la thermocline était moins prononcée. La comparaison des courants mesurés avec les courants de dérive d’ekman et les courants géostrophiques ont révélé que les structures thermohalines et biogéochimiques sont influencées par les vents de moussons du Sud-Ouest (MSO) et du Nord-Est (MNE). Les MSO qui soufflent de juin à aout, déplacent les eaux de surface du Golfe de Tadjourah vers le Golfe d’Aden et induisent la remontée des eaux profondes à l’ouest et l’intrusion par le nord-est des eaux salée de la thermocline. Celle-ci se rapproche de la surface particulièrement à l’ouest où elle se mélange avec les eaux de surface. En revanche, les vents de moussons du nord-est (MNE) prédominants de novembre à mai, emmènent les eaux froides vers le Golfe de Tadjourah. Le mélange convectif profond épaissit la CM. Cette thèse montre que les vents de moussons et leur renverse saisonnière jouent un rôle crucial dans la stratification de la colonne d’eau et que la topographie du bassin influence et module leurs effets. Durant l’été, la forme en cuvette du bassin et la pente continentale plus allongée à l’ouest favorise l’upwelling à l’ouest du golfe où les anomalies de la SST et de fortes concentrations de la CHLa ont été observées
The objective of this thesis is to study the physical and biogeochemical characteristics of the pelagic habitat (0-200m), its spatio-temporal variability and the processes that govern them in the Gulf of Tadjourah (Djibouti).Singular spectrum analysis (SSA) and empirical orthogonal function (EOF) were applied to two data sets derived from AVHRR_MetopA radiometry and sea colour sensors (Modis and Meris). These statistical analysis shows that the variability of sea surface temperature (SST) and chlorophyll a concentration (CHLa) are mainly explained by annual and semi-annual cycles. The annual cycle of SST consists of an alternation between warmer (April to October) and cooler (November to March) surface water. The semi-annual cycle shows a slight drop of SST between July and August, particularly in the west of the gulf. For the CHLa, the variability is fully dominated by the annual cycle indicating summer enrichment of seashore water (July-November) with a strong seaward gradient which is reversed from October to May. Multichannel spectrum analysis (M-SSA) and cross correlation function analysis applied to the oceanic (SST, CHL-a) and atmospheric parameters (wind speed, air temperature and humidity) showed that the annual cycle of SST is connected to heat flux at the air-sea interface, while the summer drop of SST and its associated CHL-a increase were attributed to upwelling. In the second part, in order to elucidate this oceanic influence on SST and CHL-a, the vertical thermohaline and biogeochemical structures of the upper layer (0-200 m) were studied using high-resolution hydrographic data collected in July-August 2013, September 2013 and February 2014. During summer, the superficial layer consisted of the mixed layer (ML) extending to a depth of about 20-30 m, followed by the thermocline located between 30 and 50 m depth. The ML was thicker in the west and the southeast where the thermal gradient and chlorophyll a concentrations were particularly high. During September, this stratification persisted but the ML became warmer and saltier and the thermocline moved slightly deeper. In February, the ML extended to about 120 m, and the thermocline was less pronounced. A comparison of the directly measured currents to the wind induced Ekman currents and to geostrophic current profiles revealed that the thermohaline and the biogeochemical features were related to the southeast and northeast monsoon winds (SWM & NEM). Between June and August, the SWM drives surface water from the Gulf of Tadjourah to the Gulf of Aden and thus induces the westward intrusion of high salinity thermocline water from the Gulf of Aden. This near surface flow mixes surface waters in the extreme west of the Gulf of Tadjourah. In contrast, the NEM which blow from September to May, bring cold water toward the Gulf of Tadjourah and thickens the ML through convective mixing. Our thesis shows that the monsoon winds and their seasonal reversal play a crucial role in the stratification of the water column, but that their effects are additionally influenced by basin topography. During summer the bowl-shape of the basin and its elongated slope in the west enhance the upwelling in this area where negative sea surface temperature anomalies and high chlorophyll a concentrations were observed

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Low, Michael Christopher. "Empire of the Hajj pilgrims, plagues, and pan-Islam under British surveillance,1865-1926 /." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-07082007-174715/.

Повний текст джерела

Анотація:

Thesis (M.A.)--Georgia State University, 2007.
Stephen H. Rapp, committee chair; Donald M. Reid, committee member. Electronic text (210 p. : ill. (some col.), maps, facsim.) : digital, PDF file. Description based on contents viewed Dec. 20, 2007; title from file title page. Includes bibliographical references (p. 192-210).

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Armand, Leanne. "The use of diatom transfer functions in estimating sea-surface temperature and sea-ice in cores from the southeast Indian Ocean." Phd thesis, 1997. http://hdl.handle.net/1885/143822.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

DeBlander, Evan F. "Relationship between tropical Atlantic Sea surface temperature variability and southern Indian Ocean tropical cyclones." Thesis, 2012. http://hdl.handle.net/1957/29750.

Повний текст джерела

Анотація:

Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social impact of tropical cyclones, it is important to investigate how an Atlantic-Indian Ocean connection may be affecting tropical cyclone behavior in the southern Indian Ocean. In this study, the International Best Track Archive for Climate Stewardship (IBTrAC) tropical cyclone database is used to derive metrics of tropical cyclone behavior, which are then compared with indices of tropical Atlantic SST variability representing Atlantic Niño, and Benguela Niño events. Changes in tropical Atlantic SSTs are found to coincide with significant differences in tropical cyclone activity for portions of the southern Indian Ocean. In addition, for these same regions, tropical Atlantic SST variability is associated with changes in large-scale atmospheric conditions, including steering flow, low level vorticity, and humidity, typically associated with tropical cyclogenesis, and tropical cyclone track. The changes in steering flow related to both indices of Atlantic SST anomaly are reproduced by an atmospheric model. The changes in steering flow are also found to be linked to changes in TC translational velocity, and TC tracking. These findings indicate a possible link between tropical Atlantic conditions and cyclone activity in the Indian Ocean mediated through a teleconnection between tropical Atlantic SSTs and large scale atmospheric conditions over the southern Indian Ocean. The teleconnection related to the Benguela Niño region of SST variability was found to consist of a Rossby wave initiated off the coast of South America, and propagating into the Indian Ocean, thereby influencing several atmospheric variables, including steering flow. The teleconnection related to the Atlantic Niño region of SST variability was not well defined, although there was some evidence of a Walker circulation anomaly extending from the equatorial Atlantic over the continent of Africa, and influencing SIO steering flow.
Graduation date: 2012

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Muller, Anne. "Deep-sea sediment core and coral reconstructions of the Late Quaternary paleoceanography of the eastern Indian Ocean." Phd thesis, 2002. http://hdl.handle.net/1885/151776.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Khasenye, Valentine Ochanda. "An integrated approach towards vulnerability assessment of climate-change induced sea level rise along the Kenyan coast." Thesis, 2017. https://hdl.handle.net/10539/24595.

Повний текст джерела

Анотація:

A dissertation submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, in partial fulﬁlment of the requirements for the degree of Doctor of Philosophy.
Currently, 48% and 71% of the infrastructure for Mombasa and Lamu respectively falls within the Low Elevation Coastal Zones (LECZ) of less than 10m thus highlighting their extreme vulnerability under the pessimistic sea-level-rise (SLR). Based on the primary objective of assessing the impacts of climate-change-induced SLR for the two island cities, this study finds that by the end of this century, close to 50% of Mombasa Island and almost 71% of Lamu Island fall under threat of inundation from SLR enhanced storm surges of a one storm surge in 100 years. The study objectives were to assess initial SLR vulnerability levels for the Kenyan coast, analyse status quo vulnerability perceptions and awareness, co-produce mitigation and adaptation policy options and produce an integrated vulnerability assessment atlas and manual for SLR along coastal cities, with participatory processes as a key component. SLR scenario modelling using GIS techniques (and guided by Intergovernmental Panel on Climate Change IPCC) under two SLR scenarios of Regional Concentration Pathways (RCP 2.6 and RCP 8.5), was applied to estimate the spatial extent, population, and infrastructure under threat. Participatory Action Planning (PAR) based on a mini-charrette was used to analyse status quo perception and awareness of SLR and related impacts followed by co-creation of adaptation and mitigation strategies. Under RCP 2.6 (optimistic-scenario) the simulation findings indicate that exposure level to the 1:100 storm surge for Mombasa County at 4m elevation falls between 433,300 and 2.5 million people and over US$9.1 billion in assets exposed by 2090. Under RCP 8.5 (pessimistic-scenario) for Lamu, the exposure level of between 37,200 and 480,400 people and over US$ 648 million in infrastructure/assets is exposed by 2090. Under increased urbanization, vulnerability for both Mombasa and Lamu increases to over 2.6 million inhabitants and US$ 14.5 Billion and US$ 1.2 Billion respectively by 2090 under RCP 8.5. The participatory process showed improvement in the awareness of SLR impacts by participants in both islands and thus constituted the basis of co-production of adaptation and mitigation strategies as well as finalisation of the vulnerability atlases of the island cities. Keywords: Sea-level-rise, vulnerability assessment, climate change, Kenyan coast and coastal planning.
GR2018

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Bharathraj, G. N. "Bay of Bengal Freshwater in the tropical Indian Ocean." Thesis, 2006. https://etd.iisc.ac.in/handle/2005/4977.

Повний текст джерела

Анотація:

The annual total continental runoff into the Bay of Bengal (BoB) is more than half the runoff into the entire tropical Indian Ocean. The net freshwater (FW) content in the Bay of Bengal mixed layer increases from a minimum of 6200 km3 in May to a maximum of 8700 km3 in November. For steady state freshwater balance, there has to be a net transport of around 0.11 Sv (1 Sv = 106 m3s−1) out of the Bay. This large transport of freshwater has a significant influence on regional hydrological balance. In this thesis, we investigate the seasonal pathways of BoB freshwater based on climatological observations. In order to trace the movement of BoB freshwater in the tropical Indian Ocean, we remove the influence of local precipitation minus evaporation by subtracting seasonal P-E from FW at each point. Although this recipe does not remove advected rainwater for simplicity we call the difference “runoff water” (RW), as the major source of this water is continental runoff as well as freshwater from the Indonesian Throughflow (ITF). The datasets used in this work are (1) World Ocean Atlas 2001 Salinity and Temperature (2) Satellite-gauge merged precipitation from GPCP and CMAP (3) SOC and COADS evaporation (4) Surface currents from WOCE drifters (5) Dai and Trenberth River Runoff Data (6)SK197 Cruise data from north Bay in October 2003 (7) NIOT Buoy observations, including DS1 thermistor chain data and (8) Sea Surface Temperature from TRMM Microwave Imager (TMI). Estimates suggest that the net annual input of freshwater into the Bay (from runoff plus rain minus evaporation) is more than 4000 km3. The upper ocean freshwater content is highest in the north Bay in the post monsoon season. We also study the effect of the upper ocean freshwater pool on ocean cooling due to cyclones in the north Bay. We find two principal pathways for the export of freshwater out of the northern Bay of Bengal. These pathways had been identified in previous model studies. However, most models underestimate the true reach of Bay of Bengal freshwater because model mixing is unrealistically large. The two pathways are as follows: (1) The western pathway, during November-May. Observations, and a few model studies using passive tracers and drifters, suggest that runoff water from the north Bay flows down the east coast of India in the East India Coastal Current (EICC) and into the eastern Arabian Sea around Sri Lanka during November-December. Later in winter, water from south Bay flows past Sri Lanka in the Northeast Monsoon Current (NMC) (January-February). We see BoB freshwater in the Arabian Sea up to 15 0N along the west coast of India in February, with RW decreasing gradually to the north. Bay runoff spreads in the southern Arabian Sea up to the coast of Africa by May. Upper ocean currents around the Lakshadweep high and smaller vortices (January-April) might then carry the BoB water west. (2) The eastern pathway, during the second half of the year, carries BoB freshwater south. The surface water flows along the Indonesian coast, joins the Indonesian Throughflow and flows west in the surface south equatorial current (SEC), in agreement with some model results. High space and time resolution sea surface temperature (SST) from satellite shows that premonsoon cyclones cool SST in the Arabian Sea(AS) and the southern Bay of Bengal by up to 50C, but post monsoon cyclones do not cool the north Bay by more than 10C. In situ data is used to examine the possible reasons for the small SST cooling in the north Bay, even under strong post-monsoon cyclones. The cyclone of June 1998 in the eastern AS passed within 200 km of the NIOT mooring DS1. The thermistor chain on DS1 showed strong thermal stratification in the upper ocean before the storm developed. The cyclone deepened the mixed layer from about 10 m or less to about 70 m. The potential energy input to the upper ocean is about 11,000 Jm−2. We do not have similar subsurface temperature profiles, recording the influence of a cyclone in the north Bay. We use CTD data from Sagar Kanya cruise SK197 in October 2003 and ask the question: What would happen to north Bay SST if 11,000 Jm−2 of potential energy were supplied by a cyclone to mix the upper ocean? We find that the mixed layer would deepen from about 10 m to 40 m, but this would not lead to significant SST cooling because the isothermal layer is around 40 m deep. This suggests that vertical mixing due to post monsoon cyclones does not lead to SST cooling of the north Bay because (a) salinity stratification resists deep vertical mixing, and (b) the sub mixed layer water is warm. Therefore, the observed cooling of under 10C must be mainly due to evaporation.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Behara, Ambica. "Effect of Rainfall and River Discharge on the North Indian Ocean." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/4102.

Повний текст джерела

Анотація:

In the north Indian Ocean, the Bay of Bengal (BoB or bay) and the Eastern Arabian Sea (EAS) receive a huge amount of rainfall during summer. Several rivers along their boundaries discharge enormous amounts of freshwater into the coastal regions. Strong near-surface stratification induced by rainfall and river discharge has been linked to warmer sea surface temperature (SST) of the BoB, which forms as a favourable ground for the formation and intensification of the monsoon disturbances during summer. In this thesis, the influence of rainfall and river discharge on the dynamics and thermo-dynamics of the BoB and the EAS is studied using an ocean general circulation model (OGCM). We use an eddy-permitting Indian Ocean model based on MOM4p1 (Modular Ocean Model version 4.1), with a horizontal resolution of 26 km. The vertical resolution of the model varies from 5 m in the top 60 m and the resolution gradually decreases with depth below 60m. The upper ocean hydrography and circulation of the north Indian Ocean is reproduced very well by the model. Individual and combined effects of rainfall and river discharge on the BoB is investigated using the model. A set of four sensitivity experiments, forced with same air-sea heat flux, but retaining either river runoff or rainfall or both are carried out. These experiments show that the river water is exported out of the bay along the western boundary during winter and rain water along the eastern boundary during summer. Runoff leads to a large ( >3 psu) decrease in salinity in the northern bay during summer and along the western boundary during winter, with a weaker contribution from rainfall. The East Indian Coastal Current strengthens by 10 15 cm sec 1 during winter owing to river discharge. The SST response to freshwater forcing shows large vi spatial variations with eastern bay showing higher differences. The north-western bay warms by 1.5 C in the presence of freshwater during summer, due to greater heat absorption within a shallow mixed layer (ML). This warming is caused in nearly equal proportions by rain and river water in early summer, but the contribution by river water dominates during peak and withdrawal phases of the summer monsoon. North-eastern bay, in contrast, is cooler by 1.5 3 C in the presence of freshwater, caused primarily by river runoff, owing to the winter cooling over a thin ML. Temperature inversions form due to surface cooling of a river strati ed layer during winter in the northwestern bay and due to radiation penetrating below the ML during summer in the northeastern bay. The west coast of India and the adjoining EAS is one of the high rainfall zones of Indian summer monsoon. The summer monsoon rainfall in this region is about 1036 km3, which is comparable to that of the Ganga-Brahmaputra river system. We have investigated the impact of EAS rainfall on the Arabian Sea salinity with a suite of experiments using the model. The role of low-salinity water originating in the BoB on reducing the EAS salinity has also been examined. The sea surface salinity (SSS) of EAS decreases progressively from June to September by 0.5 to 1 psu. A numerical experiment that isolates the e ect of EAS rainfall suggests that this SSS decrease is due to local rainfall. The spatial pattern of SSS decrease, however, is influenced by the prevailing West India Coastal Current. The SST in the southern EAS cools by 0.5 C in response to EAS rainfall freshening during summer. The SST cooling in the presence of salinity stratification is attributed to the enhanced upwelling along the southwest coast of India. In the southeastern Arabian Sea, during winter, the SSS decreases by about 1.5 psu. This freshening is caused by rainfall during the early winter in the southwestern BoB between 6 15 N. Neither rainfall to the north of 15 N nor river runoff into the BoB contribute much to the SEAS freshening during winter. The northern bay has been known to remain warm (>28.5 C), which favour the deep atmospheric convection, during summer. The study has been able to identify the individual and combined effects of rainfall and river discharge on the northern BoB. The near-surface salinity stratification allows the northwestern bay to remain warmer during the summer. The cooling in the northeastern bay, in the presence of freshwater forcing, points out the significance of ocean-atmosphere coupling along the eastern boundary of the bay. The local rainfall maintains the surface salinity of EAS below 36 psu throughout the year. Interestingly, the summer monsoon upwelling along the southwest coast of India is stronger in the presence of near-surface stratification induced by the EAS rainfall. The possible implications of this strong upwelling in response to local rainfall and river discharge along the west coast of India on its ecological system needs to be studied.
CSIR HOOFS

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Parampil, Sindu Raj. "Observed Subseasonal Variability Of Temperarture And Salinity In The Tropical Indian Ocean." Thesis, 2011. https://etd.iisc.ac.in/handle/2005/2040.

Повний текст джерела

Анотація:

Subseasonal variability of tropical Indian Ocean sea surface temperature is thought to influence the active-break cycle of the Asian monsoon. There are several open questions related to the role of surface fluxes, large-scale ocean circulation and subsurface ocean processes in the subseasonal variability of upper ocean temperature. We present a unified study of the subseasonal (2-90 day) variability of surface heat flux and upper ocean temperature and salinity throughout the tropical Indian Ocean in all seasons. We focus on the relation between surface fluxes and ocean response using a new satellitebased daily heat flux. The role of ocean processes (advection, entrainment and mixing) in determining SST variability is diagnosed from the daily satellite SST. Before the onset of the summer monsoon, sea surface temperature (SST) of the north Indian Ocean warms to 30-32oC. Climatological mean mixed layer depth in spring (March-May) is 10-20 m, and net surface heat flux (Qnet) is 80-100 Wm􀀀2 into the ocean. It has been suggested that observed spring SST warming is small mainly due to (a) penetrative flux of solar radiation through the base of the mixed layer (Qpen), (b) advective cooling by upper ocean currents and (c) entrainment of sub-mixed layer cool water. We estimate the role of the first two processes in SST evolution from a two-week ARMEX experiment in April-May 2005 in the the southeastern Arabian Sea. The upper ocean is stratified by salinity and temperature, and mixed layer depth is shallow (6 to 12 m). Current speed at 2 m depth is high even under light winds. Currents within the mixed layer are quite distinct from those at 25 m. On subseasonal scales, SST warming is followed by rapid cooling. The cooling occurs although the ocean gains heat at the surface - Qnet is about 105 Wm􀀀2 in the warming phase, and 25 Wm􀀀2 in the cooling phase; penetrative loss Qpen, is 80 Wm􀀀2 and 70 Wm􀀀2. In the warming phase, SST rises mainly due to heat absorbed within the mixed layer, i.e. Qnet minus Qpen; Qpen, reduces the rate of SST warming by a factor of three. In the second phase, SST cools rapidly because (a) Qpen, is larger than Qnet, and (b) advective cooling is _85 Wm􀀀2. A calculation using time-averaged heat fluxes and mixed layer depth suggests that diurnal variability of fluxes and upper ocean stratification tends to warm SST on subseasonal time scale. Buoy and satellite data suggest that a typical premonsoon intraseasonal SST cooling event occurs under clear skies and weak winds, when the ocean is gaining heat. In this respect, premonsoon SST cooling in the north Indian ocean is different from that due to MJO or monsoon ISO. As a follow-up to ARMEX, we use a short dataset from a field campaign in the premonsoon north Bay of Bengal to study diurnal variability of SST. In addition to the standard meteorological and hydrographic parameters measured from shipborne instruments and buoy sensors, we obtained a two-hourly record of subsurface sunlight profiles. Heat fluxes are seen to drive the SST warming during the day while both advection and entrainment/mixing are important during the night. The simple heat balance based on heat flux shows that it drives the diurnal cycle of SST, though ocean processes contribute towards night time cooling; this has been confirmed using the Price-Weller-Pinkel mixing model forced by heat flux and wind stress. A similar analysis for mixed layer salinity revealed that the salt balance in the region is dominated by advection rather than freshwater flux or entrainment/mixing. Buoy and satellite data show pronounced subseasonal oscillations of sea surface temperature (SST) in the summertime north Indian Ocean. The SST oscillations are forced mainly by surface heat flux associated with the active-break cycle of the south Asian summer monsoon. The input of freshwater (FW) from summer rain and rivers to the Bay is large, but not much is known about subseasonal salinity variability. We use 2002-2007 observations from Argo floats with 5-day repeat cycle to study the subseasonal response of temperature and salinity to surface heat and freshwater flux in the central Bay of Bengal and central Arabian Sea. Estimates of surface heat and freshwater flux are based on daily satellite data sampled along the float trajectory. We find that intraseasonal variability (ISV) of mixed layer temperature is mainly a response to net surface heat flux minus penetrative radiation during the summer monsoon season. In winter and spring, however, temperature variability appears to be mainly due to ocean processes rather than local heat flux. Variability of mixed layer freshwater content is generally independent of local surface flux (precipitation minus evaporation) in all seasons. There are occasions when intense monsoon rainfall leads to local freshening, but these are rare. The large subseasonal fluctuations observed in FW appear to be due to advection, suggesting that freshwater from rivers and rain moves in eddies or filaments. We have developed a new daily satellite-based heat flux dataset for the tropical Indian Ocean (30oE 􀀀 120oE; 30oS 􀀀 30oN); satellite data include surface air temperature and relative humidity from the Atmospheric Infrared Sounder (AIRS). On the seasonal scale (> 90 days) the flux compares reasonably well with climatologies and other daily data. On the subseasonal scale, our flux product has realistic behaviour relative to buoy data at validation sites. An important result is that ocean processes (advection, entrainment/detrainment, mixing at the base of the mixed layer) cool the tropical Indian Ocean SST by 8oC over the year. The largest contribution of ocean processes (_20oC SST cooling over the year) is in the western equatorial Indian Ocean. Ocean processes generally cool the upper ocean in all seasons and all regions, except in boreal winter, when they warm the north Indian Ocean. This is likely due to entrainment of warm sub-mixed layer water in regions of inversions. On subseasonal (2-90 days) scales, the contribution of air temperature and humidity to latent heat flux is roughly equal to the contribution from wind speed variability: Another interesting finding is that the contribution of air temperature and humidity increases away from the equator. One of the most important contributions of this thesis is the demonstration that tropical Indian Ocean SST has a coherent response to intraseasonal changes in heat flux associated with organised convection in the summer hemisphere. SST responds to flux in (i) the northeast Indian Ocean during May-October and (ii) the 15oS-5oN region during November-April. In the winter hemisphere and in regions with no organised convection, it is ocean processes and not fluxes which drive the subseasonal changes in SST. This result suggests that SST ISV feeds back to organise and sustain organised convection in the tropical atmosphere.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Parampil, Sindu Raj. "Observed Subseasonal Variability Of Temperarture And Salinity In The Tropical Indian Ocean." Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/2040.

Повний текст джерела

Анотація:

Subseasonal variability of tropical Indian Ocean sea surface temperature is thought to influence the active-break cycle of the Asian monsoon. There are several open questions related to the role of surface fluxes, large-scale ocean circulation and subsurface ocean processes in the subseasonal variability of upper ocean temperature. We present a unified study of the subseasonal (2-90 day) variability of surface heat flux and upper ocean temperature and salinity throughout the tropical Indian Ocean in all seasons. We focus on the relation between surface fluxes and ocean response using a new satellitebased daily heat flux. The role of ocean processes (advection, entrainment and mixing) in determining SST variability is diagnosed from the daily satellite SST. Before the onset of the summer monsoon, sea surface temperature (SST) of the north Indian Ocean warms to 30-32oC. Climatological mean mixed layer depth in spring (March-May) is 10-20 m, and net surface heat flux (Qnet) is 80-100 Wm 2 into the ocean. It has been suggested that observed spring SST warming is small mainly due to (a) penetrative flux of solar radiation through the base of the mixed layer (Qpen), (b) advective cooling by upper ocean currents and (c) entrainment of sub-mixed layer cool water. We estimate the role of the first two processes in SST evolution from a two-week ARMEX experiment in April-May 2005 in the the southeastern Arabian Sea. The upper ocean is stratified by salinity and temperature, and mixed layer depth is shallow (6 to 12 m). Current speed at 2 m depth is high even under light winds. Currents within the mixed layer are quite distinct from those at 25 m. On subseasonal scales, SST warming is followed by rapid cooling. The cooling occurs although the ocean gains heat at the surface - Qnet is about 105 Wm 2 in the warming phase, and 25 Wm 2 in the cooling phase; penetrative loss Qpen, is 80 Wm 2 and 70 Wm 2. In the warming phase, SST rises mainly due to heat absorbed within the mixed layer, i.e. Qnet minus Qpen; Qpen, reduces the rate of SST warming by a factor of three. In the second phase, SST cools rapidly because (a) Qpen, is larger than Qnet, and (b) advective cooling is _85 Wm 2. A calculation using time-averaged heat fluxes and mixed layer depth suggests that diurnal variability of fluxes and upper ocean stratification tends to warm SST on subseasonal time scale. Buoy and satellite data suggest that a typical premonsoon intraseasonal SST cooling event occurs under clear skies and weak winds, when the ocean is gaining heat. In this respect, premonsoon SST cooling in the north Indian ocean is different from that due to MJO or monsoon ISO. As a follow-up to ARMEX, we use a short dataset from a field campaign in the premonsoon north Bay of Bengal to study diurnal variability of SST. In addition to the standard meteorological and hydrographic parameters measured from shipborne instruments and buoy sensors, we obtained a two-hourly record of subsurface sunlight profiles. Heat fluxes are seen to drive the SST warming during the day while both advection and entrainment/mixing are important during the night. The simple heat balance based on heat flux shows that it drives the diurnal cycle of SST, though ocean processes contribute towards night time cooling; this has been confirmed using the Price-Weller-Pinkel mixing model forced by heat flux and wind stress. A similar analysis for mixed layer salinity revealed that the salt balance in the region is dominated by advection rather than freshwater flux or entrainment/mixing. Buoy and satellite data show pronounced subseasonal oscillations of sea surface temperature (SST) in the summertime north Indian Ocean. The SST oscillations are forced mainly by surface heat flux associated with the active-break cycle of the south Asian summer monsoon. The input of freshwater (FW) from summer rain and rivers to the Bay is large, but not much is known about subseasonal salinity variability. We use 2002-2007 observations from Argo floats with 5-day repeat cycle to study the subseasonal response of temperature and salinity to surface heat and freshwater flux in the central Bay of Bengal and central Arabian Sea. Estimates of surface heat and freshwater flux are based on daily satellite data sampled along the float trajectory. We find that intraseasonal variability (ISV) of mixed layer temperature is mainly a response to net surface heat flux minus penetrative radiation during the summer monsoon season. In winter and spring, however, temperature variability appears to be mainly due to ocean processes rather than local heat flux. Variability of mixed layer freshwater content is generally independent of local surface flux (precipitation minus evaporation) in all seasons. There are occasions when intense monsoon rainfall leads to local freshening, but these are rare. The large subseasonal fluctuations observed in FW appear to be due to advection, suggesting that freshwater from rivers and rain moves in eddies or filaments. We have developed a new daily satellite-based heat flux dataset for the tropical Indian Ocean (30oE 120oE; 30oS 30oN); satellite data include surface air temperature and relative humidity from the Atmospheric Infrared Sounder (AIRS). On the seasonal scale (> 90 days) the flux compares reasonably well with climatologies and other daily data. On the subseasonal scale, our flux product has realistic behaviour relative to buoy data at validation sites. An important result is that ocean processes (advection, entrainment/detrainment, mixing at the base of the mixed layer) cool the tropical Indian Ocean SST by 8oC over the year. The largest contribution of ocean processes (_20oC SST cooling over the year) is in the western equatorial Indian Ocean. Ocean processes generally cool the upper ocean in all seasons and all regions, except in boreal winter, when they warm the north Indian Ocean. This is likely due to entrainment of warm sub-mixed layer water in regions of inversions. On subseasonal (2-90 days) scales, the contribution of air temperature and humidity to latent heat flux is roughly equal to the contribution from wind speed variability: Another interesting finding is that the contribution of air temperature and humidity increases away from the equator. One of the most important contributions of this thesis is the demonstration that tropical Indian Ocean SST has a coherent response to intraseasonal changes in heat flux associated with organised convection in the summer hemisphere. SST responds to flux in (i) the northeast Indian Ocean during May-October and (ii) the 15oS-5oN region during November-April. In the winter hemisphere and in regions with no organised convection, it is ocean processes and not fluxes which drive the subseasonal changes in SST. This result suggests that SST ISV feeds back to organise and sustain organised convection in the tropical atmosphere.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Rodd, William. "Geopolitical impact of China's search for energy on the Indian Ocean and South China Sea." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-304425.

Повний текст джерела

Анотація:

This thesis examines the geopolitical consequences of China's search for energy resources on the Indian Ocean and South China Sea. It provides a brief outline of the energy situation of the world as a whole, specifically how it is becoming a more globalized and singular market. This change is occurring at the same time as a pronounced shift away from the traditional measurements of 'power' towards 'softer' more subtle definitions. There is a brief section outlining the geopolitical teachings of Alfred T. Mahan, specifically how he advocated seapower primarily for the purpose of providing the stability and security necessary for trade. Chinese analysts have been embracing the teachings of Mahan, but also interpreting them in a way that justifies the naval buildup Beijing has been embarking on in recent years. The paper briefly looks at the potential sources that China could turn to meet its energy needs, but concludes that it will have to rely on oil for the foreseeable future. It then attempts to define overall Chinese interests, specifically how nearly all of these relate somehow to energy security, thus underlining the importance of this topic to leaders in Beijing. The last half of the work delves into a geopolitical analysis of the Indian Ocean and South China Sea, and how militarization in the...

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Ormston, Robert. "The growth of the Indian navy : what is India up to?" Thesis, 1991. http://hdl.handle.net/1885/144423.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Bishara, Fahad Ahmad. "A Sea of Debt: Histories of Commerce and Obligation in the Indian Ocean, c. 1850-1940." Diss., 2012. http://hdl.handle.net/10161/5497.

Повний текст джерела

Анотація:

This dissertation is a legal history of debt and economic life in the Indian Ocean during the nineteenth and early-twentieth century. It draws on materials from Bahrain, Muscat, Bombay, Zanzibar and London to examine how members of an ocean-wide commercial society constructed relationships of economic mutualism with one another by mobilizing debt and credit. It further explores how they expressed their debt relationships through legal idioms, and how they mobilized commercial and legal instruments to adapt to the emergence of modern capitalism in the region.

At the same time, it looks at the concomitant development of an Indian Ocean-wide empire of law centered at Bombay, and explores how this Indian Ocean contractual culture encountered an Anglo-Indian legal regime that conceived of legal documents in a radically different way. By mobilizing written deeds in imaginative ways, and by strategically accessing British courts, Indian Ocean merchants were able to shape the contours of this growing legal regime.

Most broadly, the dissertation argues that law and courts became increasingly central to economic life in the Indian Ocean, and that economic actors in the region employed a wide range of different legal strategies in adapting to a changing world of commerce. In the Indian Ocean, as elsewhere, the histories of commerce and law were inextricably intertwined.

Dissertation

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Shiau, Yi-Jang, and 蕭義璋. "Shipping Routes in the Northern Indian Ocean – South China Sea Regions and Associated Impacts from Monsoon." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/90281613381217649508.

Повний текст джерела

Анотація:

碩士
國立高雄海洋科技大學
海事資訊科技研究所
99
Abstract Navigational safety and efficiency are the main objectives of navigation. Among numerous factors, the meteorological factors and marine weather are the most prominent and direct indicators, and are used to adjust shipping routes. This research focuses on the impacts and effects that the seasonal changes have on the Indian Ocean and the South China Sea seaways based on meteorological phenomena such as winds, waves and ocean currents. International Comprehensive Ocean–Atmosphere Data (ICOADS), International marine Meteorological Archives (IMMA), and the ocean current data acquired from OSCAR (Ocean Surface Current Analyses – Real time) website are cited for this research. Meteorological Environment Data from National Centers for Environment Prediction (NCEP) and National Center for Atmospheric Research (NCAR) are used to analyze on overall marine climate and environment affecting shipping routes. The following are the results from this research: (1) In the Northern Indian Ocean, the major routes connecting between Asia, Europe and Middle East formed a triangle shipping routes. During the summer monsoon season, strong waves in the Gulf of Aden area forces ships to change its course to other alternative routes. Due to this strong wind, ships elect to sail along north of Socotra Island to prevent potential navigational hazards caused by the high waves from the southern sea area. (2) In the South China Sea, the leading ship routes travel between the Southeast Asia and the Northeast Asia. In winter period, ship navigation are affected by strong monsoon, therefore, navigate along the adjacent coastal area to avoid strong winds and waves. (3) In the Southern Asia Sea area, the key shipping routes travel across the Bay of Bengal. In summer, due to the strong southwest monsoon, the ships travel from east to west should choose the northern sea area or navigate along the coastal line to minimize the impacts on navigation efficiency. (4) Based on the comprehensive meteorological data analysis collected from navigational observation, various data and navigation records are integrated to analyze the changes of ship routes and modify ship routes according to the seasonal changes associating with winds, waves and ocean currents. Keywords: Northern Indian Ocean, South China Sea, Monsoon, Shipping routes.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Marshall, John Francis. "Decadal-scale, high resolution records of sea surface temperature in the eastern Indian and south western Pacific Oceans from proxy records of the strontium/calcium ratio of massive porites corals." Phd thesis, 2000. http://hdl.handle.net/1885/147107.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Riskas, Kimberly Anne. "Addressing sources of data deficiency for sea turtles and fisheries in the Indian Ocean and Southeast Asia." Thesis, 2017. https://researchonline.jcu.edu.au/64402/1/JCU_64402_Riskas_2017_thesis.pdf.

Повний текст джерела

Анотація:

Marine turtle populations worldwide are threatened by a number of anthropogenic activities, of which fishing is unquestionably one of the most harmful. Though the effects of fisheries mortality have been documented across species, gear types and regions, management intervention remains constrained by data limitations even in well-monitored fisheries in developed nations. The issue of illegal, unreported and unregulated (IUU) fishing introduces further uncertainty into fisheries management regimes, with a lack of understanding of how IUU fishing activities affect marine turtle populations. For both legal and IUU fisheries, such data deficiencies hinder the development of targeted mitigation strategies for reducing fisheries-related injury and mortality of marine turtles. I chose to examine specific issues of data deficiency for marine turtles and fisheries in the Indian Ocean and Southeast Asia region (IOSEA), an area identified as having critical data needs for multiple fleet types and turtle populations. I began by demonstrating the need for cross-jurisdictional assessment of turtle bycatch in legal, regulated fisheries. I evaluated the cumulative patterns of turtle bycatch in Australia using longitudinal datasets from commercial fisheries in three separate management jurisdictions (Chapter 2). The results of this chapter point to potential cumulative impacts to vulnerable turtle populations (i.e. leatherback and olive ridley) arising from interactions with multiple fisheries. Spatial analysis revealed a bycatch 'hotspot' in the Gulf of Carpentaria, where commercial fisheries impact multiple turtle species and genetic stocks. These results illustrate the need to set cumulative, cross-jurisdictional bycatch quotas for marine turtles, and to evaluate turtle bycatch at the population level instead of separately within individual fisheries. I also stress the need for timely collaboration between management agencies in order to implement effective, biologically relevant management strategies for marine turtles and other vulnerable taxa. Next, I evaluated IUU fishing as a threat to marine turtles in the IOSEA (Chapter 3). The unlawful nature of IUU fishing makes it difficult to study directly and thus required gathering data from outside traditional bureaucratic reporting frameworks. Using the expert elicitation technique, I determined that IUU fishing is likely to have potentially significant impacts on marine turtle populations in the IOSEA through targeted exploitation, use of prohibited gears and international wildlife trafficking. IUU fishing activities were found to vary in nature and magnitude on sub-regional scales, with Southeast Asia emerging as an area of concern due to the targeted exploitation and trafficking of marine turtles by IUU vessels. This chapter constitutes the first expert consensus characterising IUU fishing as a serious threat to marine turtles. These results indicate a demonstrable need to strengthen monitoring, control and surveillance (MCS) efforts and to employ regional coordination to help build capacity in lessdeveloped nations. To complement the broad-scale assessment of IUU fishing performed in Chapter 3, I then examined IUU fishing dynamics relating to marine turtles within the Southeast Asia subregion (Chapter 4). During interviews with commercial fishers in two Malaysian states (i.e. Terengganu and Sabah), I found that the root causes of IUU fishing differ considerably between states, as do the dynamics of marine turtle capture and trade. This chapter also provides evidence linking IUU fishing vessels to the direct capture, trade and transshipment of marine turtles in Malaysia; such activities are likely to occur in other nations throughout the IOSEA, particularly where underlying situational factors are similar. Given these statespecific differences in IUU fishing practices and motivations, I conclude that the enforcement response must be similarly nuanced in order to address the varying drivers of IUU fishing in each state context. Further, an international, collaborative and pluralistic regulatory approach is needed to reduce IUU fishing and wildlife trafficking, as these are interconnected facets of a broader issue of unlawful marine resource extraction. As IUU fishing persists despite the large number of political instruments and initiatives aimed at eliminating it, an examination of the barriers to effective policy implementation and enforcement is needed. To address this need, I designed a structured survey for officials working in marine conservation, fisheries management and enforcement throughout the IOSEA (Chapter 5). Survey results indicate that while IUU fishing is considered a management priority throughout the IOSEA, on-ground action is hindered by scale mismatches and capacity shortfalls. Among management agencies in the IOSEA, there is a mismatch between the acknowledgement that inter-agency collaboration is important and the reported degree of its implementation. These results also identified a number of knowledge gaps that managers believed would be useful in reducing the incidence of IUU fishing and marine turtle exploitation. I emphasise that decentralised fisheries management strategies have the potential to develop targeted, locally-based solutions, and also present an opportunity for much-needed data-gathering. Finally, drawing partly on the results of Chapter 4, I conclude that improvements in MCS measures must develop alongside advances in understanding of the drivers and barriers present in each local context. Based on the combined results of my interdisciplinary thesis, legal and IUU fisheries interact with marine turtles in a number of ways that have consequences for the survival of turtle populations. Existing national and international instruments are not sufficiently equipped to tackle the variety of fishing-related threats to marine turtles, and instead will require adoption of cross-jurisdictional, pluralistic and potentially decentralised management approaches in order to enact change at the level of individual fishers. In Chapter 6, I emphasise the value of my approach for evaluating widespread, complex and data-limited threats, and that my contribution informs management efforts for both fisheries and marine turtles. I then conclude the thesis by identifying avenues for useful future research.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Putri, Mutiara Rachmat [Verfasser]. "Study of ocean climate variability (1959 - 2002) in the eastern Indian Ocean, Java Sea and Sunda Strait using the HAMburg shelf ocean model / vorgelegt von Mutiara Rachmat Putri." 2005. http://d-nb.info/974465585/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Punt, Charli-Ann. "Stories of liminal voyage in the Indian Ocean: Michael Ondaatje's The Cat's Table & Abdulrazak Gurnah's By the Sea." Thesis, 2014.

Знайти повний текст джерела

Анотація:

Thesis (M.A.)--University of the Witwatersrand, Faculty of Humanities, African Literature, 2013
This thesis explores two stories of voyage in the Indian Ocean. These stories are Michael Ondaatje’s The Cat’s Table and Abdulrazak Gurnah’s By the Sea. The Indian Ocean has taken its place as an important emerging area of study as it provides a unique vantage point from which to view the emerging phenomena of the Global South. The story of voyage is useful as it seems to encompass some of the crucial features and themes of the Indian Ocean world. This thesis suggests that voyages operate within a liminal space in both novels. The concept of liminality refers to a state which operates between stable states of being. In both novels the liminal space of voyage can be regarded as an ideological organizing principle which gives particular shape to the meaning expressed in the novels.

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Survival at sea – Indian Ocean"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями