Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014. / 15 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 50-51). / Abstract Errors in modeling atmospheric delays are one of the limiting factors in the accuracy of GPS position determination. In regions with uneven topography, atmospheric delay phenomena can be especially complicated. Current delay models used in analyzing GPS data from the Plate Boundary Observatory (PBO) are successful in achieving millimeter-level accuracy at most locations; however, at a subset of stations, the time series for position estimates contain an unusually large number of outliers. In many cases these outliers are oriented in the same direction. The stations which exhibit asymmetric outliers occur in various places across the PBO network, but they are especially numerous in California's Mammoth Lakes region, which served as a case study for this project. The phenomenon of skewed residuals was analyzed by removing secular trends and variations with periods longer than 75 days from the signal using a median filter. The skewness of the station position residuals was subsequently calculated in the north, east and up directions. In the cases examined, typical position outliers are 5-15 mm. In extreme cases, skewed position residuals, not related to snow on antennas, can be as large as 20 mm. I examined the causes of the skewness through site-by-site comparisons with topographic data and various forms of weather data such as numerical weather models, radiosondes, and satellite images. Analysis suggests that the direction of the skewness is generally parallel to the local topographic gradient at a scale of several kilometers. Comparison with weather data suggests that outlier data points in the Mammoth Lakes region occur when lee waves are likely to form downstream of the Sierra Nevada Mountains. The results imply that coupling between the atmosphere and local topography, e.g. lee waves, is responsible for the phenomenon of skewed residuals. / by Kathryn Materna. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985. / Microfiche copy available in Archives and Science. / Bibliography: leaves 315-317. / by Melinda Darby Dyar. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 63-67). / Many studies have investigated tropical data assimilation in the context of global models or specifically for tropical cyclones, but relatively few have focused on the mesoscale predictability and observability of the general tropical environment. This work constructs an ensemble data assimilation system for the tropics using a state of the science mesoscale prediction model, and tests the effect of a sparse observational network of wind and moisture in constraining the estimate of the state. A perfect model framework is used as a necessary first step to ease interpretation of results. Ensemble assimilation allows for state-dependent error covariances, foregoing prederived balances and correlations and allowing for the use of the full nonlinear model. Boundary conditions are necessary for limited-area models, and the perturbed lateral boundaries and initial conditions are taken from a global ensemble using a non-perturbed sea surface temperature analysis. In the mesoscale model, this uniform surface had a profound effect on moisture levels in the lower levels, rapidly bringing the spread of vapor mixing ratio to near zero. Comparing the mesoscale forecast with a downscaled global model forecast showed that the interior solution was not completely dependent on the boundary conditions. Observing system experiments that assimilated synthetic moisture and wind component observations in the boundary layer and in the free atmosphere had a small effect on the state estimate when compared with an unconstrained control case. The largest improvement was in the upper troposphere obtained by observing upper-level moisture, but several analyses were degraded by the data, due in part to the sparse network and small localization radius. / by Timothy Robert Whitcomb. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 141-152). / by Chris Eliot Forest. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991. / Vita. / Includes bibliographical references. / by Joanne Theresa Fredrich. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2004. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 37-38). / Observations of retreating subduction systems in the Mediterranean region suggest the density of subducting lithosphere is dynamically related to trench retreat rate and upper-plate deformation. Most numerical and analog studies of retreating subduction systems have not explored the effects of lithospheric density variations on subduction processes. This study is a preliminary effort to construct a two-dimensional, viscous flow model of "roll-back" subduction to explicitly examine how slab density influences retreat rate, mantle flow, and slab geometry. For a given lithosphere-mantle density contrast, the model computes the evolution of a viscous, thermal slab using a finite element code for incompressible convection (ConMan). Imposed velocity boundary conditions guide lithospheric material into a uniformly weak "subduction zone" and out into the mantle below, generating stable, asymmetric subduction. Slabs driven faster than the "intrinsic" (dynamically consistent), steady-state retreat rate of the system (vr) are characteristically arcuate, pushed upward from the base of the mantle layer by strong horizontal "return flow" beneath the descending lithosphere. Slabs driven slower than vr are sigmoidal: the slabs steepen at depth, where vertical buoyancy forces overcome lateral viscous forces set up by weak surface velocities. The diagnostic behaviors of slabs driven faster and slower than vr define a set of qualitative criteria (slab geometry, mantle flow patterns) for converging on the consistent, steady-state retreat rate of the system. For slab-mantle density contrast [delta]p = 198 kg/m³ (defined as the density difference between lithosphere at surface of the system and mantle material at the base of the system), vr ~~ 16 mm/yr. The slab is roughly planar, with 500 dip. For [delta]p = 168 kg/m³, vr is slightly slower (14 mm/yr), and steady-state slab geometry is nearly identical (moderately-dipping planar surface). It is found that the angle at which lithospheric material is forced into the mantle does not significantly affect either steady-state retreat rate or slab geometry. / by Jessica L. Haurin. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 57-58). / Transits of exoplanets were observed from June 2009 through January 2010. Six transit light curves are presented in this paper for three planets: WASP-10b, WASP- 11/HAT-P-10b, and TrES-3. Measurements of the planetary radii, semi-major axis, transit duration, and period confirmed literature values to within two sigma. Transit timing variations were not observed in these systems, but calculations show that it would be possible to measure transit timing variations induced by large exomoons (greater than about 6 Earth masses) in the WASP-11/HAT-P-10b system. Challenges of exoplanet observation from small telescopes are discussed. It was determined that overall, transit measurements of many exoplanets using small telescopes can be successful and scientifically useful. / by Caroline V. Morley. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989. / Includes bibliographical references (leaves 160-162). / by Richard Peter Signell. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Bibliography: leaves 317-322. / by Karl B. Coyner. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998. / Includes bibliographical references (p. 147-148). / by Svetlana, Valeryevna Panasyuk. / Ph.D.