Earth's atmosphere is a dynamic region with a complex interplay of energetic inputs, outputs, and transport mechanisms. A complete understanding of the atmosphere and how various fields within it interact is essential for predicting atmospheric shifts relevant for spaceflight, the evolution of Earth's climate, radio communications, and other practical applications. In-situ observations of a critical altitude region within Earth's atmosphere from 100-200 km in altitude, a subset of a larger 90 – 400 km altitude region deemed the "Thermospheric Gap", are required for constraining atmospheric models of wind, temperature, and density perturbations caused by atmospheric tides. Observations within this region that are sufficient to fully reconstruct and understand the evolution of tides therein are nonexistent. Certain missions have sought to fill portions of this observation gap, including Daedalus which was selected as a candidate for the Earth Explorer program by the European Space Agency in 2018. This study focuses on the design and optimization of a two-satellite, highly elliptical satellite constellation to perform in-situ observations and reconstruction of tidal features in the 100-200 km region. The model atmosphere for retrieving sample data is composed of DE3 and DE2 tidal features from the Climatological Model of the Thermosphere (CTMT) and background winds from the Thermosphere-Ionosphere-Electrodynamic General Circulation Model (TIEGCM). BoTorch, a Bayesian Optimization package for Python, is integrated with the Ansys Systems Tool Kit (STK) to model the constellation's propagation and simulated atmospheric sampling. A least squares fitting algorithm is utilized to fit the sampled data to a known tidal function form. Key results include 14 Pareto optimal solutions for the satellite constellation based on a set of 7 objective functions, 3 constellation input parameters, and a sample set of n = 86. Four of these solutions are discussed in more detail. The first two are the best and second-best options on the Pareto front for sampling and reconstruction of the input tidal fields. The third is the best solution for latitudinal tidal fitting coverage. The fourth is a compromise solution that nearly minimizes delta-v expenditure, while sacrificing some quality in tidal fitting and fitting coverage. / Master of Science / Earth's atmosphere, the envelope of gaseous material surrounding the planet from an altitude of 0 km to approximately 10,000 km, is a dynamic system with a diverse set of energy inputs, outputs, and transfer mechanisms. A complete understanding of the atmosphere and how various fields within it interact is essential for predicting atmospheric shifts relevant for spaceflight, the evolution of Earth's climate, radio communications, and other practical applications. The atmosphere life breathes on Earth's surface evolves in physical and chemical properties, such as temperature, pressure, and composition, as distance from Earth increases. In addition, the atmosphere varies temporally, with shifts in its properties occurring on several timescales, some as short as a few minutes and some on the order of the age of the planet itself. This thesis project seeks to study the optimization of a satellite system to further understand an important source of atmospheric variability – atmospheric tides. Just as the forces of gravity from the moon and sun cause tides in the oceans, the Earth's rotation and the periodic absorption of heat into the atmosphere from the sun cause atmospheric tides. A model atmosphere with a few tides and a background wind is generated to perform simulated tidal sampling. The latitude, longitude, and altitude coordinates of the satellites as they propagate through the atmosphere are used to model samples of the northward and southward atmospheric winds and determine how well the constellation does at regenerating the input tidal data. The integration of several software tools and a Bayesian Optimization algorithm automate the process of finding a range of options for the constellation to best perform the tidal fitting, minimize satellite fuel consumption, and cover as many latitude bands of the atmosphere as possible.

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Kelp forests are highly productive three-dimensional marine ecosystems that provide valuable ecosystem services globally. Along the coast of British Columbia, Macrocystis pyrifera and Nereocystis luetkeana are two key species that form surface-canopies that are vulnerable to both biotic and abiotic drivers; making it imperative to monitor and understand whether these ecosystems are changing in the face of climate change. The monitoring of kelp forests is commonly enhanced by use of remote sensing, which allows researchers to survey large portions of the coast where it would otherwise be difficult to collect data, and to use archived imagery for comparisons of historic and contemporary kelp forest trends. Generally, the remote sensing of kelp surface-canopy relies on differences in the high near-infrared (NIR; 700-1000 nm) signal of kelp and the low NIR signal of water. However, kelp surface-canopy reflectance signals can be affected by submergence under water, caused by oceanographic features like tides and currents, or simply due to differences in the morphology and buoyancy of kelp canopy structures. This submersion may cause uncertainties when estimating the surface-canopy area of kelp beds in remote sensing imagery. This research aims to understand the effects of submersion on the remote sensing of kelp surface-canopy. To address our goal, (i) Nereocystis canopy structures (bulb and blade) were submerged while collecting above-water hyperspectral measurements. The hyperspectral data into the bandwidths of high-resolution multispectral aerial and space-borne sensors and vegetation indices were calculated to understand the kelp detection limits when using shorter red-edge wavelengths (RE; 690-750 nm) instead of the longer NIR wavelengths. The results showed that submerged kelp can be detected deeper in the water column using shorter RE wavelengths compared to the more commonly used NIR wavelengths. Further, (ii) in situ hyperspectral data were also collected for the different surface-canopy structures and compared with UAV imagery, which showed that the buoyancy of the kelp canopy structures at the surface affected the relative magnitude of reflectance in both the RE and NIR and supported the findings of the submersion experiment. The total surface-canopy area derived from classification with both RE and NIR vegetation indices were compared in the UAV imagery, and the RE index detected roughly 18% more kelp than the NIR index, with no differences seen between Macrocystis and Nereocystis, or between high and low tide in beds larger than 150m2. Finally, (iii) to understand how submersion by tides and currents affect the ability to estimate surface-canopy area for both Macrocystis and Nereocystis, surface-canopy area was derived from multispectral unoccupied aerial vehicle (UAV) imagery and compared with in situ tide and current data, which showed that surface-canopy area had a strong negative linear relationship with tidal height at all sites regardless of species. Macrocystis occupied sites where currents were low (<10cm/s) and did not affect the surface-canopy. Therefore, the extent of all Macrocystis beds decreased at a similar rate over their tidal range (22.7 + 2.8%/m). Nereocystis beds occupied a wider range of current speeds (0.0 - 19.0 cm/s), and at sites with high current speeds (> 10 cm/s) increasing current and tidal height decreased surface-canopy area simultaneously, resulting in both a higher and more variable rate of decrease (30.5 + 9.1%/m) with increasing tidal height than Macrocystis. Together, this thesis addressed critical questions related to the effects of kelp submersion on the remote sensing of surface-canopy forming kelps, and we provide recommendation for remote sensors who wish to minimize errors when using remote sensing to map kelp forests. / Graduate

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Vita. / Bibliography: leaves 324-329. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Vita. / Bibliography : leaves 203-209. / by Douglas Scott Luther. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1981. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 95-96. / by Peter Reid Daifuku. / M.S.

When cutting an ice from lakes and ponds gaseous phase displays often ubiquitous bubble textures along the ice thickness. The occurrence of bubbles (enclosures filled with the gas) in ice relates to a content of the dissolved gas in the lake/pond water prior to freezing over the surface. When water freezes, dissolved gases are rejected and redistributed at the ice-water interface, depending on the saturation ratio between the gas and water. If the concentration of dissolved gases surpasses a critical value (as freezing progresses), the water at the interface becomes supersaturated, and gas bubbles nucleate and grow to a visible size along the interface. The bubbles generated at the ice-water interface are either incorporated into the ice crystal as the ice-water interface advances, thus forming gas pores in the ice, or released from the interface. If there is incorporation or release is determined by several factors. The bubbles nucleated at the advancing ice-water interface may be characterized by concentration, shape, and size, which depend on growth rate of ice, the amount of gases dissolved in water, and the particulate content of water. This work focused on the relation between growth rates of the ice and the occurrence of bubbles in the pond ice. I monitored the temperature of the ice formed...

O Porto de Santos está localizado no litoral Paulista, na costa Sudeste do Brasil e é o maior e mais importante porto do país. Desde 1859 vem sofrendo adaptações e modernizações tanto em suas instalações físicas quanto em sua estrutura administrativa. As variáveis com as quais a Engenharia Civil deve lidar podem ser resumidas basicamente aos fenômenos naturais, pois estes determinam como serão projetadas e construídas as estruturas e instalações. Em projetos portuários, diversas características naturais devem ser mensuradas como, por exemplo, ventos, correntes marítimas, incidência de ondas, tipo de solo em que se encontra o porto, as temperaturas médias do local e, sobretudo, o nível do mar. Os mares e oceanos não possuem superfícies estáveis e apresentam cotas que estão em movimentos constantes. Estas variações se dão basicamente por ondas de curto ou longo período. A maré é uma onda de longo período que causa a variação diária do nível do mar. Atualmente é cada vez maior o interesse da comunidade científica pela temática relacionada às variações do nível do mar. Buscando contribuir com o tema, o presente estudo tem como objetivo principal a análise das variações do nível do mar no Porto de Santos ao longo dos últimos 60 anos, utilizando-se de dados coletados nos três marégrafos da região. Foi elaborada a média móvel desta série com a finalidade de detectar alguma variação significativa. A análise dos dados implicou que fossem considerados períodos de 18,61 anos, correspondentes ao intervalo do ciclo de precessão lunar, de modo a eliminar o efeito da variação astronômica no nível do mar. A elevação do nível máximo, médio e mínimo do mar no período de 1953 a 2008, apresentou uma elevação média de 2,5 mm/ano, resultado semelhante a outros estudos. Foram avaliados também o impacto da variação do nível do mar sobre as estruturas portuárias, indicando os efeitos da elevação nas estruturas, nos cais, nos aparelhos de defensa e ancoragem, nos equipamentos de descarga e outros. / Santos Harbor is at São Paulo\'s coast, in Brazil\'s southeast coast and it is the biggest and the most important port of the country. Since 1859 had been suffering adaptations and modernizations in its installations such as in its administrative structure. The variables that Civil Engineering has to deal with can be resumed basically to the natural phenomena because its determines how projected and built the structures will be. In docks projects, several natural characteristics must be measured, as example, winds, ocean currents, waves incidence, kind of soil that supports the harbor\'s structures, the local medium temperatures and, mainly the sea level. The seas and oceans doesn\'t have stables surfaces and shows levels that are in constant movements. These variations are products of short and long period waves. The tide is a long period wave that causes the daily sea level variation. Actually, the interest of the scientific community in sea level variation is increasing. Aiming to contribute with this theme, the present study has as main objective analyzing the sea level variations at Santos Harbor above the last 60 years, using data collected from three tidal gauges in the region. It was applied the moving average of the series to detect some significant variation. The data analysis demanded that the periods of 18,61 years, which corresponds to the interval of the moon precession cycles, was considered to purge the astronomic variation over the sea level. The maximum sea level, average and minimum sea level, in the period of 1953 and 2008 showed an average increase of 2.5 mm/year, which is similar to other studies. It was evaluated the impact of this sea level rise over the port\'s structures, showing the structural effects, over the docks; in the defense and anchorage equipment, unload equipment and others.

Reform ideas, such as results measurement and management, tend to come and go in different ‘tides of reforms’. The purpose of this thesis is to increase our understanding of tides of reforms by identifying and discussing mechanisms that drive the rise, as well as the fall, of management reforms. This is done by studying four so-called ‘results initiatives’ launched at Sida, the Swedish International Development Agency in 1971, 1981, 1998 and 2012. The thesis tries to understand what happened both in Sida’s external environment as well as within the agency prior to the initiation, during implementation and when the four results initiatives fell out of favor. The life of each of the four results initiatives can be understood as having taken place in five phases: 1) the pressure phase, 2) the launch, 3) implementation, 4) point of re-do or die, 5) phase of opening up for something new. During these five phases different internal and external mechanisms contributed to either further institutionalization or to de-institutionalization of the results measurement and management ideas and technologies. It is argued that the need to gain legitimacy can be seen as the main mechanism that has driven the initiation of the results initiatives. During implementation, problems and difficulties arise. It is argued that whilst resistance towards the initiatives, as well as changed external demands, accelerates de-institutionalization, these mechanisms do not explain why the initiatives fall. In turn, the failure to find a standardized reporting category for “results”, the non-use of the results information produced and the fact that the initiatives no longer fulfill the function of providing legitimacy, are mechanisms that lead to the final death of the initiatives. The study concludes that whilst different external pressures can be considered important in initiating reforms, it is mainly internal mechanisms, within the organization, that explain the reason why the initiatives fall. Earlier literature has argued that tides of reforms are driven by hope and optimism to be and to be seen as effective. The findings in this study show that also the solidarity rationale, i.e. the wish to do good for someone else, and the feeling of doing so, drives the reforms. It is moreover argued that the reforms are also driven by fear and other emotions. In general, the occurrence of tides of reforms can be understood by the tension between the two rationales in development aid: solidarity and effectiveness. The study contributes with insights to what happens within an organization and over a longer time perspective when public agencies are faced with conflicting demands. It provides a broader understanding of reasons behind the quest to report on results and also what happens when results are not reportable. Since new and similar reforms will most probably arise in the future, findings from this study ought to be interesting not only in development aid but in all public policy sectors, for any policy maker or practitioner involved in the implementation of such reforms. / <p>Degree: Fil Dr in Economics </p><p>Research funder: Sida, Swedish International Development Agency </p> / The results agenda in Swedish Development Cooperation /SCORE