Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000. / Includes bibliographical references (p. 246-256). / Observations of the vertical structure of stratospheric planetary waves reveal a large variety of structures, and a variability both on seasonal and on daily time scales. The extent to which linear wave theory explains these structures and their time evolution at a given time or season is not well known. The sensitivity of linear wave models to details of the basic state and model damping, both of which are not determined from observations in great accuracy, makes it hard to determine why the observations deviate from modeled waves in any given case. In addition, the ability of the observations to resolve the vertical structure of planetary waves is not obvious, given the low vertical resolution of satellite retrievals. The goal of this thesis is to understand the sources of observed variability of vertical wave structure, in particular, to determine whether linear wave theory can explain this variability, and whether the observations are capable of resolving it. We start by testing the ability of satellite retrievals to resolve the vertical structure of the waves. We calculate the radiances that a virtual satellite sitting at the top of our model atmosphere would see, and invert them to obtain retrieved temperature fields. The comparison to the model temperatures suggests that the retrievals are able to resolve their general features quite well, with a few exceptions. Above 1.5mb there is little observed information in the retrievals, and errors start growing above 5 mb. Also, small scale features are not resolvable, but most waves have large enough vertical wavelengths to be resolved. We also identify dynamic situations in the real atmosphere which are more prone to retrieval errors. These are mostly relevant to summer or to the breakup of the polar vortex, when the existence of critical surfaces may cause the waves to have sharp features. The next part consists of understanding the relation between vertical wave structure and the wave propagation characteristics of the basic state in a series of linear wave models, both steady state and time dependent. We study the normal modes on a one dimensional (vertical) troposphere-stratosphere system, using a framework of wave geometry, which allows us to generalize the results to many basic states. A large variety of vertical wave structures is found, similar to observed. This variety is due to the existence of stratospheric turning points. We extend these results to basic states that vary in latitude and height in a nonseparable way. The main problem is how to separate the wave propagation into the vertical and meridional directions. Our approach is diagnostic, where we calculate meridional and vertical wavenumbers from the steady state wave solution to a given basic state, and use them as a diagnostic of the basic state wave propagation characteristics. In particular, we are able to determine the location of turning surfaces for meridional and vertical propagation. By applying this wavenumber diagnostic to many model runs we show that the existence of a stratospheric waveguide renders the problem qualitatively one dimensional by determining the meridional wavenumber, regardless of the characteristics of the tropospheric forcing. In particular, the effects of damping and turning surfaces on the vertical structure are qualitatively as in the vertical propagation problem. In a complementary study, we regard the waves as consisting of many wave activity packets that propagate from the troposphere through the stratosphere, until they dissipate. A technique that follows a wave packet on its journey through the stratosphere, while keeping track of variations in wave activity that are due to refraction of the waves, is introduced and applied to the model runs. This allows us to separate between the contributions to the wave activity budget of damping, refraction, and time variations in the source of wave activity. Also, we can estimate the time scale for vertical propagation through the stratosphere of specific wave events. Finally, we use our diagnostics to study observed wave episodes. We show that the differences in vertical wave structure between middle and late winter episodes in the southern hemisphere can be explained as a linear response to the seasonal evolution of the basic state wave propagation characteristics. We also show that the occasional daily time scale variations of vertical wave structure within a given wave episode are qualitatively a linear response to time variations of the basic state wave propagation characteristics. Since the basic state variations are wave driven, the relevant theory is quasi-linear. Estimates of wave propagation time scales, obtained using our wave activity diagnostic, are also consistent with the theory. We take this is a qualitative assessment of the applicability of quasi-linear wave propagation theory on daily time scales, as well as an assessment of the observations of the waves and the basic state. The latter is not obvious since most of the relevant variations in the basic state occur above 5mb, where observations are less accurate. / by Nili Harnik. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The extinction at the Permian-Triassic boundary marked one of the most profound events of the Phanerozoic Eon. Although numerous hypotheses have been proposed, the trigger mechanism continues to be debated. This thesis intends to examine the impact of oceanic conditions on the extinction event by analyzing hydrocarbon biomarkers. Hydrocarbon biomarkers are chemical fossils in sedimentary rocks that serve as proxies to measure the conditions that prevailed during deposition. In this thesis, biomarkers for redox conditions, depositional environment, microbial community and potential age-related biomarkers have been measured and are reported from four sections that span the Permian-Triassic boundary. The first section, from the Peace River Basin in modern-day western Canada, was deposited on the eastern margin of the Panthalassic Ocean and samples conditions in this global water body. The second section is from Kap Stosch, Greenland, and was deposited on the southern margin of an epicontinental sea situated in the northwest of the supercontinent Pangaea. The Great Bank of Guizhou, China is the third section studied, and it is a carbonate platform deposited on the southern edge of one of the smaller continental blocks that formed the eastern margin of the Paleo-Tethys Ocean. The fourth section, for the Permian-Triassic boundary is from Meishan, China, the type section for this boundary, and was deposited on the western margin of another one of the continental blocks at the edge of the Paleo-Tethys Ocean. The biomarker evidence from these sections was measured in ratios, absolute abundances and for 613C isotopic values. This evidence points to global marine conditions dominated by bacterial inputs in which photic zone euxinia was prevalent for extended time periods. Additional findings from compound-specific isotope data suggest that at isolated intervals, the chemocine may have extended even closer to the surface. The timing of these intervals implies that ocean conditions may have affected the extinction itself. / by Lindsay Elizabeth Hays. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001. / CDROM contains entire thesis in PDF format. / CDROM copy of thesis held by MIT Institute Archives only. / Includes bibliographical references. / This thesis addresses the complexity of both syn- and post-orogenic extension in the overriding plate during Caledonian continental collision through field and laboratory investigations in the central East Greenland Caledonides. During the course of this work, attempts were made to answer some of the outstanding regional and local questions in East Greenland geology. Structural, U-Pb and ⁴⁰Ar/³⁹Ar geochronologic, petrographic and thermobarometric data were combined to constrain and reconstruct a portion of the tectonic history of this orogen. Most extension was accommodated along a system of orogen-parallel, N-S striking normal faults known as the Fjord Region Detachment (FRD) system. The FRD system comprises two temporally distinct, but overlapping, splays just south of 73⁰ N. The lowermost splay is called the Hogedal detachment was active from ca. 417 to 380 Ma, and was active for a second time as recently as ca. 357 Ma. The uppermost splay is the Tindern detachment. This fault was active from ca. 425-423 Ma, exhuming material at rates as fast as 6.5 mm/year. Continued extension in the hanging-wall of this fault accounts for additional denudation at much slower rates over a 25 my time-period. In-between activity on these faults, there is evidence to suggest that middle-crustal thickening continued to occur. Thus, the East Greenland Caledonides preserve evidence for crustal thickening (minimum -16 km) and orogen parallel shear, followed by rapid upper-middle crustal thinning (-13 km), followed by coeval middle-crustal thickening (unknown amount) and upper-crustal thinning (5 km), and ending with crustal collapse (-16 km thinning). / (cont.) This is the first time that an alternation between thrusting and normal faulting has been observed in an over-riding plate during continent-continent collision, and only the second time that it has ever been documented in a collisional orogen. The data imply that there was a fundamental cyclicity between crustal thickening and thinning, consistent with dynamical models of orogenesis in which plate-forces responsible for contraction and gravitational forces responsible for extension, oscillate between periods where one dominates. Furthermore, given the established relationship between topography and synorogenic extension in active mountain belts, it is likely that activity along the Tindern detachment, the earliest splay of the FRD, was controlled by Caledonian paleotopography that formed during the initial stages of orogenesis. The fact that most middle- and upper-crustal extension was restricted to the FRD implies that a localized inherent crustal weakness may have developed after initial movement along the Tindern detachment. Given that late-stage Devonian activity on the FRD may have played a prominent role in the formation of the Devonian basins, which themselves likely controlled the geometry and location of subsequent Mesozoic extension and formation of the North Sea basins, the implication is that the position of rifting of the north Atlantic ocean was partially [pre-determined] inherited from the initial Caledonian paleotopography. / by Arthur P. White. / Ph.D.

Thesis: Ph. D. in Atmospheric Chemistry, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 197-219). / This thesis explores ways in which single particle mass spectrometry can be extended, whether through hardware improvements, or through the use of advanced data processing techniques to provide new kinds of aerosol chemistry measurements. Most of this work has been carried out using the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument, an aircraft deployable mass spectrometer that uses intense (~10 9 Wcm -2 ) UV laser pulses to vaporize and ionize single particles and measures their mass spectra using a time-of-flight mass spectrometer. Near-term and long-term hardware improvements as well as advanced data analysis techniques are explored in order to extract new chemical information from the thus obtained single particle mass spectra. Hardware improvements to PALMS are explored, such as the use of a high-powered femtosecond laser to obtain single particle mass spectra and a new high resolution compact mass analyzer. Also, a new commercial mass spectrometer LAAPToF is characterized and compared to PALMS. In addition to hardware improvements, novel data analysis techniques for analysis of single particle mass spectra were developed as a part of this work. In particular, a new method to identify biologically-derived particles is presented and used to derive vertical profiles of bioaerosol from near-surface to the upper troposphere. / by Maria Anna Zawadowicz. / Ph. D. in Atmospheric Chemistry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1986. / Microfiche copy available in Archives and Science / Bibliography: leaves 218-224. / by David Scott Gutzler. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989. / Includes bibliographical references (leaves 207-208). / by Richard Leigh Baron. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002. / Includes bibliographical references (leaves 111-113). / In this thesis, I explore the use of non-linear wavelet techniques to estimate the order and scale of velocity discontinuties in the mantle transition zone through waveform analysis of Pds converted waves. The converted phases are isolated through a single station/multiple event receiver function technique which uses a wavelet deconvolution and denoising known as WaRD. It is an edge-preserving damped least squares solution with a small water level and subsequent wavelet thresholding. The deconvolved data is then imaged through an imaging technique which maps the conversions to the depth domain. The Pds phases are then isolated through a windowing and weighting, and then matched to a fractional order spline using a greedy matching pursuit algorithm. The data for this study consists of 2 Australian stations, CAN (Geoscope) and WRAB (IRIS), and 5 Japanese stations (JIZ, SGN, TKA, TMR, and TYM) from the F-Net array (formerly Freesia). CAN and WRAB are located in a relatively quiet continental tectonic setting, while the Japanese stations are in a more complex subduction zone environment. TKA (southern Japan) and TMR (northern Japan) are each thought to be underlain by a single subducting slab. JIZ, SGN, and TYM are located in central Japan where the Pacific and Philippine plates meet, and the subduction zone is thought to be very complex, with 2 slabs intersecting directly below these stations. Order and scale estimates for both Pds phases were obtained for CAN, WRAB, and SGN, and only P410s and P660 estimates were obtained for JIZ and TYM, respectively. Signal complexity in the image stacks prevented the determination of order estimates in either Pds phase for TKA and TMR. Order and scale estimates for the 410km discontinuity range between 0.325-0.450, and 18-35, respectively. Estimates for the order and scale of the 660km discontinuity range between 0.225-0.325 and 23-31, respectively. The order estimates for the P410s at CAN and WRAB were lower (0.325) than the estimates at JIZ and SGN (0.400-0.450), while the order estimates for the P660s at CAN and WRAB were higher (0.325-0.350) than the estimates for SGN and TYM (0.225-0.275). The results are consistent with a mixture type model in which the shape of the velocity discontinuity is a cusp-like feature and is caused by a critical density of one mineral phase with another. The ability to determine the order and scale and possible lateral variations could have major implications for the current views of discontinuities in the mantle transition zone. / by Hugh Franklin Cox. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2003. / Cataloged from PDF version of thesis. Pages 15, 16 and 35 not in original thesis. / Includes bibliographical references (pages 38-40). / A snowfall potential probability density function is introduced that uses an alternate method of statistical analysis in predicting snowfall by using concepts of normal probability distributions. The snowfall potential function (hereby referred to as the SPF) assumes certain identifiers are associated with snowfall of varying intensities. The conceptual relation of each identifier with snowfall is explained and the statistical association of each identifier to the SPF is determined by a correlation coefficient and the relative strength of that particular identifier with respect to the expected value (the mean). The intensity of the snowfall over an area is estimated by calculating the SPF's overall deviation from some expected value, where any given SPF value can estimate a snowfall value. The framework for the SPF is explained using a simple model. The correlation coefficients for several identifiers are calculated and an example of an application of the SPF is demonstrated. Further hypotheses are given as to how the SPF could ultimately be used to provide possible higher-accuracy snowfall forecasts through the development of time-dependent functions for each identifier and the assigning of specific functional forms for the SPF based on region of analysis, storm type (i.e.: coastal, Alberta clipper), and storm track. 2 / by Wesley C. Acosta. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988. / Three maps (folded) in pocket attached to inside back cover. / Includes bibliographical references. / by Kurt Richard Sternlof. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1995. / Includes bibliographical references (leaves 143-146). / by Keith D. Alverson. / Ph.D.