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Earth, Atmospheric, and Planetary Sciences - Bachelor's degree

Mostrando recursos 1 - 20 de 187

  1. The relationship between Centaur activity and ring formation

    Tigges, Sophia E
    Introduction: Centaurs are small bodies whose orbits lie between those of Jupiter and Neptune (Gehrels, 1999). They are thought to be transition objects that originate in the Kuiper belt and occupy the cis-Neptunian region before potentially becoming Jupiter-family or other short-period comets (Dones, Levison, & Duncan, 1996). Their short dynamical lifetimes are on the order of 106 years (Horner, Evans, & Bailey, 2004) due to their unstable, planet-crossing orbits (Horner, Evans, Bailey, & Asher, 2003). Some Centaurs have been observed to be active, and the bodies in the population of active Centaurs have perihelion distances that are statistically smaller than...

  2. X-ray determination of the solid solubility of silver in cadmium

    Cuthbert, Stuart Verne
    Stuart Verne Cuthbert, Jr.

  3. Trade and the environment : the political economy of CO₂ emission leakage with analysis of the steel and oil sands industries

    Chan, Gabriel Angelo Sherak
    Introduction: In 2007, scientists and governmental officials from around the world contributed to the United Nations-authorized Intergovernmental Panel on Climate Change's (IPCC) Fourth Assessment Report. Through peer-reviewed scientific research and governmental review, the IPCC came to the conclusion that "warming of the climate system is unequivocal," and that "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations." The IPCC Fourth Assessment states that humans have "more likely than not" contributed to the phenomena of more frequent "warm spells/heat waves," larger "area[s] affected by...

  4. Pre-eruptive conditions beneath Medicine Lake Volcano, California, during the Pleistocene epoch

    Hooper, Heather J. (Heather Julie), 1975-
    This investigation uses the variations in composition of lavas and mineralogical evidence to characterize the preeruptive conditions beneath Medicine Lake Volcano (MLV) during the Pleistocene epoch. Prior to this investigation, the Pleistocene lavas of MLV had not been extensively studied because detailed time relations among them were not known. Recent work by Donnelly-Nolan has provided a time framework for relating these lavas, and has afforded us the opportunity to perform this study. Whole rock analyses for major elements, trace elements, and rare earth elements were performed, as well as electron microprobe analyses of individual minerals in the lavas. These analyses...

  5. Using machine learning for hydrocarbon prospecting in Reconcavo Basin, Brazil

    Zhakiya, Elezhan
    Machine Learning techniques are being widely used in Social Sciences to find connections amongst various variables. Machine Learning connects features across different fields that do not seem to have known mathematical relationships with each other. In natural resource prospecting, machine learning can be applied to connect geochemical, geophysical, and geological variables. However, the biggest challenge in machine learning remains obtaining the data to train the ML algorithms. Here, we have applied machine learning on data extracted from maps via image processing. While the overall accuracy of prediction remains as low as 33% at this stage, we see places where the...

  6. A machine-learning approach to aerosol classification for single-particle mass spectrometry

    Christopoulos, Costa (Costa D.)
    Compositional analysis of atmospheric and laboratory aerosols is often conducted via single-particle mass spectrometry (SPMS), an in situ and real-time analytical technique that produces mass spectra on a single particle basis. In this study, machine learning classification algorithms are created using a dataset of SPMS spectra to automatically differentiate particles on the basis of chemistry and size. While clustering methods have been used to group aerosols into broad categories based on similarity, these models do not incorporate known aerosols labels and are not explicitly formulated for classification. Furthermore, traditional methods often rely on a smaller set of well-known, important variables...

  7. The Mercurian magma ocean, first crust, and implications for planetary formation mechanisms

    Brown, Stephanie Marie, S.M. Massachusetts Institute of Technology
    The size of the Mercurian core and the low ferrous iron bearing silicate content of its crust offer constraints on formation models for the planet. Here we consider a bulk composition that allows endogenous formation of the planet's large core, and by processing the mantle through a magma ocean, would produce a low-iron crust. More Earth-like bulk compositions require silicate removal, perhaps by a giant impact, to create the planet's large core fraction. The earliest crusts expected in a giant impact scenario are discussed in comparison to the endogenous model. We find that the endogenous model can produce a large...

  8. The impact of Arctic cloud water and ice on cloud radiative forcing during the Arctic Summer Cloud-Ocean Study in August 2008

    Maroon, Elizabeth A
    The Arctic atmosphere is especially sensitive to changes in climate forcing; however, Arctic processes and feedbacks are not understood well enough to accurately predict how the Arctic environment might change under anthropogenic forcing. Further study of the basic atmospheric processes is needed, especially due to uncertainties in modeling cloud feedbacks. August and September are the months when the Arctic sea surfaces begin to freeze; clouds play an important role in determining when this process begins. In this study, the radiative properties of Arctic stratocumulus are studied by comparing measurements for two days in August 2008 during the Arctic Surface Cloud...

  9. The contact relationship between an large orogenic ultramafic massif and its surrounding units: Beni Bousera northern Morocco

    Piasecki, Alison M
    by Alison Piasecki.

  10. High precision U/Pb geochronology on the Cenomanian Dakota Formation, Utah : implications for paleobotany and the transgression of the Western Interior Seaway preceding Oceanic Anoxic Event 2

    Meyer, Laura (Laura B.)
    The Dakota Formation was deposited during the Cenomanian, a time when the Western Interior Seaway spanned much of North America. The Dakota Formation contains a rich record of plant and animal fossils. Key to understanding their importance, it is imperative to precisely place the Dakota Formation within the geological time scale. Volcanic ash samples interlayed with fossil bearing sandstones of the Dakota were collected from two localities in Westwater, and Henrieville, Utah. Samples were dated using isotope dilution thermal ionization mass spectrometry (ID-TIMS). The samples collected from the Westwater, Utah localities have a weighted mean 206Pb/238U date of 97.656±0.082 Ma,...

  11. A paleomagnetic study of the angrite Sahara 99555

    Slotznick, Sarah Pearl
    Sahara 99555 (SAH 99555) is the oldest dated angrite sample, a rare type of meteorite, and is only ~2 Myr younger than the age of the solar system (1, 2). SAH 99555 shows no post-cooling brecciation or weathering from the parent body, and does not display signs of significant terrestrial weathering. Therefore, paleomagnetic experiments were conducted for the first time on SAH 99555 to discover if it contains a primary paleomagnetism and then to determine a paleointensity estimate and its ferromagnetic mineralogy. Our studies show that the primary ferromagnetic mineral in SAH 99555 is magnetite and there are also some...

  12. U-Pb geochronology of the Acasta Gneiss Complex in Northwest Canada

    Safipour, Roxana G
    The Acasta Gneiss Complex in Northwest Canada contains the oldest dated rocks in the world. The gneisses range in age from 4.03-3.6 Ga, as determined by U-Pb dating of zircons (Bowring and Williams 1999). U-Pb dating of xenocrystic cores in these zircons indicates a cryptic record of continental crust older than 4.0 Ga. In this study, zircons were selected and characterized from thirteen samples of Acasta Gneisses. Many of the zircons contain xenocrystic cores mantled by younger domains. U-Pb geochronological data were collected using laser ablation inductively coupled plasma mass spectrometery (LA-ICPMS). Twelve of the samples show evidence for two...

  13. Paleomagnetism conglomerate test on Archean conglomerate rock from Jack Hills, Australia

    Bowens-Rubin, Rachel
    A paleomagnetism study known as a conglomerate test was run on an Archean sandstone conglomerate rock to determine if the sample contained a remnant magnetization from the time of its formation. Twenty-nine clasts from a thin section of the sample were thermally demagnetized up to a temperature of 395°C. The heating revealed two components of magnetization which were unblocked at low and mid temperatures, revealing a magnetic mineralogy of Pyrrhotite.Eight matrix samples were heated to a temperature of 650°C which revealed two components of magnetization at mid and high temperatures, providing evidence for a magnetic mineralogy of Hematite.The direction of...

  14. A global and tropical quasi-decadal oscillation of the atmosphere and Ocean

    Agard, John Vincent
    An oscillatory, quasi-periodic signal with a period of around 10 years was found in radiosonde- and satellite-measured datasets of lower stratospheric temperature. Power spectrum analysis and Fourier decomposition were used to characterize the temporal and vertical manifestations of the signal, while EOF analyses were used to analyze its spatial characteristics. The oscillation was found to be unrelated to the solar activity cycle, while it displayed coherence with similar oscillatory signals in ENSO, PDO and AMO indices, as well as with a quasi-decadal signal in SST data. Finally, the quasi-decadal signal in lower stratospheric temperature was found to have a small...

  15. Developing proxy radar data with the aid of cloud-to-ground lightning for a nowcasting system

    Munsell, Erin B
    Air traffic managers need up to date nowcast information over the entire CONUS for efficient operations in the National Airspace System. In areas of degraded or no radar coverage, cloud-to-ground lightning (provided by the National Lightning Detection Network) can provide valuable information through the creation of proxy vertically integrated liquid (VIL) and echo tops (ET). To develop these lightning-VIL and lightning-ET relationships, analysis of the lightning and radar data was done in "climate zones" throughout the CONUS, due to the potential for different lightning behavior in different areas of the country. After a quantile analysis revealed differences in the data...

  16. Theoretical detection limits and error reduction for radial velocity observations of an Earth-like exoplanet

    Moberger, Allison L
    The intent of this project was to determine the relationship between the number of radial velocity observations of an Earth-twin exoplanet and the error in the mass calculated from the detected signal. If the planet's period is known through prior transit observations, the mass may be measured by radial velocity more accurately; this project tested and measured the conditions for this error reduction. Simulated sets of radial velocity data taken by HARPS (accurate to 1 m/s) for an Earth-mass planet in a circular, edge-on, 1 AU orbit around a Sun-like star were used with a least-squares fit to measure the...

  17. Mantle thermal evolution of tidally-locked super-earths

    Gelman, Sarah E. (Sarah Eva)
    Most super-Earth (mass < 10M[mathematical symbol]) detection techniques are biased towards massive planets with close-in orbits. A planet's orbital decay timescale decreases with a lower semi-major axis, thereby providing a high probability of detecting exoplanets which are in tidal-lock with their star. We model the effect of fixed stellar flux on an Earth-like planet's mantle convection structure and evolution using an axisymmetric finite element fluid convection code, SSAXC. Three punctuating evolutionary steps have been identified. First, a sequence of three initial downwellings form at the antistellar point, the substellar point, and at the terminator. After approximately 250,000 years, lithospheric instabilities...

  18. Determining the effects of ocean perturbations on marine phytoplankton assemblages

    Foreman, Alan Dean
    The ocean provides a dynamic, constantly changing environment for marine phytoplankton. Understanding the effects of these changes on phytoplankton assemblages is fundamental when trying to anticipate future responses of primary producer's community to long-term environmental changes. In this study, artificial perturbation experiments were successfully performed on natural assemblages of phytoplankton to simulate conditions consistent with ocean acidification and North Pacific Subtropical Gyre (NPSG) upwelling patterns. These experiments demonstrated the feasibility and value of such perturbations in studying phytoplankton responses to environmental forcing.

  19. An overview of the volcano-tectonic hazards of Portland, Oregon, and an assessment of emergency preparedness

    Jordan, Alexandra M
    Portland, Oregon, lies within an active tectonic margin, which puts the city at risk to hazards from earthquakes and volcanic eruptions. The young Juan de Fuca microplate is subducting under North America, introducing not only arc magmatism into the overlying plate, but also interplate and intraplate seismicity related to the subduction zone. Large crustal earthquakes are also probable in Portland because of the oblique strike-slip Portland Hills Fault zone. These hazards create risk to Portland residents and infrastructure because of pre-existing vulnerabilities. Much of Portland's downtown area, including the government and business districts, is at risk of ground shaking infrastructure...

  20. The formation history of Olympus Mons from paleo-topography

    Jozwiak, Lauren M
    The formation of the volcano Olympus Mons, is linked directly to the geodynamic history of both Tharsis, and Mars as a whole. We sought to constrain the bulk formation period using paleo-topographic evidence. On the northeastern edge of the flexural trough, we located a lava flow whose path is radically discordant with current down-slope directions, indicating entrenchment prior to large-scale flexural trough formation. To constrain the end of bulk formation, we used the aureole deposits that surround the flanks of Olympus Mons, and were a consequence of crustal fracture under the weight of Olympus. Applying crater retention age dating to...

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