Oceans cover 71% Oceans cover 71% surface of the earth and are rich in oil and gas resources, marine living resources, renewable energy, mineral resources. The depths of the oceans are often thought of as a silent world, but that was never the case, and oceans have become noisier as human technologies have advanced. Humans have not only added noise to the ocean; they have also eliminated natural sounds. One of the primary noise sources is sonar. Sonar technology is widely used in fish detection, ocean floor mapping, and vehicle navigation. The noise in the ocean dramatically affects the animal’s survival and breaks marine ecological balance. Herein, underwater wireless optical communication (UWOC) and fiber communication and sensing (FC&S) technologies are proposed to minimize the acoustic noise in the ocean. Compared to noisy, powerful acoustic communication technology, UWOC has the merit of silence and takes advantage of high bandwidth, high transmission speed, and power efficiency. Multi-functions FC&S system turns the submarine telecommunication cable network into sensor network. UWOC and underwater FC&S technology can boost the development of Underwater Internet of things (UIoT) by establish large-scale underwater sensor networks. This dissertation aims to investigate and address noisy ocean issues and build large-scale underwater sensor networks by optical communication and sensing technology. The dissertation proposes using UWOC and FC&S technology to replace the conventional acoustic communication technology and reduce the noise in the ocean. UWOC helps achieve high-speed wireless communications between sensors, vehicles, and even humans for UIoT. The significant challenges of developing UWOC systems are the complex underwater environment's attenuation, scattering, and turbulence effects. This dissertation studied the turbulence effects on the UWOC system’s performance and addressed the pointing-acquisition-and-tracking issues. The diffuse-line-of-sight configuration and scintillating-fiber-based detector help the mobile UWOC systems relieve the strict requirements on PAT. FC&S technology is proposed to build underwater communication and sensor networks. Studies pave the way for UIoT and keep ocean silent. Such modality is much sought-after for implementing robust UWOC links in a complex oceanic environment, building large-scale sensor networks across the oceans, and minimizing noise pollution in the ocean.

<p>The aim of this thesis was to estimate and possibly quantify ocean flow by utilizing conventional and novel observational methods as well as model results. Motionally induced voltages, from a cable-based observational system in the Baltic Sea, were analysed to determine their utility for ocean monitoring. The data set was examined as regards the influence of single- and multi-layer flow. Correlation analyses undertaken in the first study showed that the geoelectric installation is capable of providing good estimates of the net flow across the Visby-Västervik transect. The second study focused on possible effects of multi-layer flow on the signal. Comparisons were made with tidal-gauge geostrophic flow estimates, and a good agreement was found, except for a few brief winter periods characterized by significant discrepancies. The velocity fields from a three-dimensional model showed that these events coincided with strong surface and bottom currents, and hence the attenuated voltage signal was suggested as being caused by the non-uniform velocity distribution.</p><p>The third study dealt with the deep-water flow through the Understen-Märket trench. Observational data indicated that this flow could be described by applying hydraulic theory. Since the passage is narrow compared to the internal Rossby radius of deformation, rotational effects could be neglected to lowest order. The theoretical predictions proved to agree well with the observational results.</p><p>The final study examined the effects of the heat flux and the wind forcing on the circulation in Bahía de Concepción, Chile, where three field surveys were undertaken during the extended austral summer 2002. Hydrographic and current measurements were compared to local tidal-gauge records. Rough estimates of the barotropic and the baroclinic flow across the transect indicated an unusual vortex circulation during periods of weak wind forcing and strong surface heating; results which were corroborated by numerical simulations.</p>

The aim of this thesis was to estimate and possibly quantify ocean flow by utilizing conventional and novel observational methods as well as model results. Motionally induced voltages, from a cable-based observational system in the Baltic Sea, were analysed to determine their utility for ocean monitoring. The data set was examined as regards the influence of single- and multi-layer flow. Correlation analyses undertaken in the first study showed that the geoelectric installation is capable of providing good estimates of the net flow across the Visby-Västervik transect. The second study focused on possible effects of multi-layer flow on the signal. Comparisons were made with tidal-gauge geostrophic flow estimates, and a good agreement was found, except for a few brief winter periods characterized by significant discrepancies. The velocity fields from a three-dimensional model showed that these events coincided with strong surface and bottom currents, and hence the attenuated voltage signal was suggested as being caused by the non-uniform velocity distribution. The third study dealt with the deep-water flow through the Understen-Märket trench. Observational data indicated that this flow could be described by applying hydraulic theory. Since the passage is narrow compared to the internal Rossby radius of deformation, rotational effects could be neglected to lowest order. The theoretical predictions proved to agree well with the observational results. The final study examined the effects of the heat flux and the wind forcing on the circulation in Bahía de Concepción, Chile, where three field surveys were undertaken during the extended austral summer 2002. Hydrographic and current measurements were compared to local tidal-gauge records. Rough estimates of the barotropic and the baroclinic flow across the transect indicated an unusual vortex circulation during periods of weak wind forcing and strong surface heating; results which were corroborated by numerical simulations.

An approximate of the Green's function can be obtained by taking the cross-correlation of ambient noise that has been simultaneously recorded on separate sensors. This method is applied for two experiments, which illustrate the advantages and challenges of this technique. The first experiment is in the ultrasonic regime [5-30] MHz and uses capacitive micromachined ultrasonic transducer arrays to image the near field and compares the passive imaging to the conventional pulse-echo imaging. Both the array and target are immersed in a fluid with the sensors recording the fluid's random thermal-mechanical motion as the ambient noise. The second experiment is a passive ocean monitoring experiment, which uses spatiotemporal filtering to rapidly extract coherent arrivals between two vertical line arrays. In this case the ambient noise in the frequency band [250 1500] Hz is dominated by non-stationary shipping noise. For imaging purposes, the cross-correlation needs to extract the Green's function so that the imaging can be done correctly. While for monitoring purposes, the important feature is the change in arrivals, which corresponds to the environment changing. Results of both experiments are presented along with the advantages of this passive method over the more accepted active methods.

The history of Newfoundland is intimately tied to its relationship with the sea, to its island status and its consequent cultural isolation, to its reliance on fishing and more recently oil. But it is also one of tides - of prosperity and loss, migration and resettlement, of occupation and erasure. This research is an investigation into the nature of mutable landscapes – shifting settlements, resources and infrastructures. It is recognized that the needs of each community and the resources of each environment are diverse in type and supply. The spatialization of an energy infrastructure has the opportunity to link, in a dynamic system, the ecological, political, cultural, and historical constituents atomized communities. It has the potential to be a dynamic system that forces a presence in the everyday lives of a cultural habitat. This investigation tests the possibility for a contemporary energy infrastructure, usually hidden from the cultural landscape, to become a physically and culturally pronounced manifestation of a layered historical narrative. This work exhumes histories of Newfoundland and uncovers omnipresent themes of mutability, shifting, movement, and transience, presenting the history of Newfoundland as a fluctuating story of the sea. These stories not only frame the historical spatializations of Newfoundland’s population, its infrastructures, and economies through various media, but they also simultaneously outline the social and economic deficiencies of modern approaches to developing the island. Structured chronologically, the research forms the basis for an investigation into new ideas for an infrastructure off the southern coast of Newfoundland. This design project exemplifies themes of shifting and movement through a mobile, water-based energy, research, and cultural infrastructure. It is situated off the southern coast of Newfoundland and engages both the land and the sea. This thesis does not try to tame, resolve, or control the sea. The sea is always itself, ordered by its own cycles of tides, currents and ecologies. One can really only synchronize the relationships between land and sea.

The history of Newfoundland is intimately tied to its relationship with the sea, to its island status and its consequent cultural isolation, to its reliance on fishing and more recently oil. But it is also one of tides - of prosperity and loss, migration and resettlement, of occupation and erasure. This research is an investigation into the nature of mutable landscapes – shifting settlements, resources and infrastructures. It is recognized that the needs of each community and the resources of each environment are diverse in type and supply. The spatialization of an energy infrastructure has the opportunity to link, in a dynamic system, the ecological, political, cultural, and historical constituents atomized communities. It has the potential to be a dynamic system that forces a presence in the everyday lives of a cultural habitat. This investigation tests the possibility for a contemporary energy infrastructure, usually hidden from the cultural landscape, to become a physically and culturally pronounced manifestation of a layered historical narrative. This work exhumes histories of Newfoundland and uncovers omnipresent themes of mutability, shifting, movement, and transience, presenting the history of Newfoundland as a fluctuating story of the sea. These stories not only frame the historical spatializations of Newfoundland’s population, its infrastructures, and economies through various media, but they also simultaneously outline the social and economic deficiencies of modern approaches to developing the island. Structured chronologically, the research forms the basis for an investigation into new ideas for an infrastructure off the southern coast of Newfoundland. This design project exemplifies themes of shifting and movement through a mobile, water-based energy, research, and cultural infrastructure. It is situated off the southern coast of Newfoundland and engages both the land and the sea. This thesis does not try to tame, resolve, or control the sea. The sea is always itself, ordered by its own cycles of tides, currents and ecologies. One can really only synchronize the relationships between land and sea.