Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991. / Includes bibliographical references (leaves 13-15). / by Deborah A. Zervas. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1986. / Microfiche copy available in Archives and Science. / Bibliography: leaves 162-172. / by Bernard Celerier. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (unnumbered pages 56-59). / Sulfur and carbon stable isotope ratios and organic biomarker abundance were performed on drill core samples from the Coppercap Formation of the Coates Lake Group in the Windermere Supergroup of the MacKenzie Mountains to reconstruct an environmental condition proceeding the first Neoproterozoic Snowball Earth event. The Coppercap Formation directly underlies the Rapitan Group, Sturtian glacigenic deposits, and represents a depositional environment existing directly before the Cryogenian glacial episodes. Based on aryl isoprenoids, n-propyl cholestane, isopropyl cholestane, total organic carbon, carbonate mineral analysis, [delta]34S from pyrite, [delta]13Corganic and [delta]13Ccarbonate values, environmental conditions of the Coppercap Formation were reconstructed. The Coppercap Formation was found to be a shallow euxinic marine basin with purple and green sulfur bacteria microbial mats. This suggest persistent hydrogen sulfide rich waters in the shallow photic zone persisted until the Sturtian. / by Katherine S. Thomas. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2007. / Includes bibliographical references (p. 74-76). / The mechanisms of variability of a coupled atmosphere-ocean model are investigated through the study of two coupled configurations: an aquaplanet in which gyres are absent, and an aquaplanet in which a ridge extending from pole to pole supports gyres. Empirical Orthogonal Functions (EOFs) are used to explore the main features of variability exhibited by extended integrations of both configurations. In the aquaplanet a decadal variability is observed in the atmosphere and the ocean. Stochastic driving of the annular modes in the atmosphere generates an anomalous Sea Surface Temperature (SST) dipole through latent heat fluxes and Ekman pumping. A feedback of this SST dipole on the atmosphere enables a damping slow enough for anomalies to persist over decadal time scales. This air-sea feedback combined with a slow advection of the anomalies by mean ocean currents result in the observed decadal oscillation. A simple stochastic model captures the essence of this mechanism. In the ridge decadal variability is absent but centennial variability is observed in the atmosphere and the ocean. Stochastic driving of the annular modes in the atmosphere generates a weak SST tripole due to latent heat fluxes. The weak amplitude of this tripole prevents the existence of any significant air-sea feedback, implies a stronger damping than in the aquaplanet, and ultimately results in the absence of oscillations. The classic stochastic model of Hasselmann [19] explains the evolution of the SST anomaly through time. Within a delay of one year stochastic atmospheric variability additionally generates a baroclinic streamfunction as well as baroclinic Rossby waves at the eastern boundary of the basin. The former is slowly advected by the mean flow while the latter propagates towards the western boundary, inducing a feedback on the atmosphere with a delay of sixty years. A simple model is found to capture the essence of this mechanism. The results of the aquaplanet and the ridge are used to interpret the Drake, a third configuration in which a band of land extends from the North Pole to the line of -45' of latitude. In the northern hemisphere of the Drake mean state and variability are similar to the ones observed in the ridge. The observed centennial oscillation would correspond to a decadal oscillation in the Atlantic. In the southern hemisphere of the Drake, mean state and variability have elements of both the ridge and the aquaplanet. / by Claude Abiven. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994. / Includes bibliographical references (leaves 176-179). / by Gail Lynn Christeson. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988. / Vita. / Includes bibliographical references. / by William Charles Tittemore. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993. / Vita. / Includes bibliographical references (leaves 61-62). / by Elfatih Ali Babiker Eltahir. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2005. / Includes bibliographical references (p. 238-248). / This thesis examines the dynamics of equable climates. The underlying physics of two mechanisms by which weak meridional temperature gradients might be maintained are studied. First, I examine the evolution of stratospheric dynamics and winter temperatures when the surface temperature gradient and tropospheric eddy energy decrease in order to assess whether large-scale conditions are more favorable for polar stratospheric cloud formation. Second, I examine whether the combination of high carbon dioxide and interactive, tropical cyclone dependent ocean mixing is sufficient to maintain a weak temperature gradient. I examine planetary wave generation, the energetics of the general circulation, and vertical wave propagation in a general circulation model with a resolved stratosphere forced with a weak surface temperature gradient. Compared to the present climate, transient eddy energy decreases, but stationary eddy energy does not. The polar tropopause rises, which supports a weaker temperature gradient in the lower stratosphere, a weaker stratospheric jet, and an increase in the wave activity vertically propagating into the stratosphere. / (cont.) As a result, the residual mean circulation strengthens and temperatures in the polar stratosphere change little even when the surface temperature gradient is quite weak. Temperatures in the Arctic polar vortex remain much warmer than radiative equilibrium, inhibiting large-scale polar stratospheric cloud formation. The height of the extratropical tropopause rises and the tropospheric lapse rate follows a moist adiabat when surface temperatures are warm, suggesting convection plays a significant role in setting extratropical tropospheric stratification during warm climates. The second part of the thesis addresses the role of tropical cyclone induced mixing in the oceans' general circulation. I examine the sensitivity of the oceans' meridional overturning circulation and heat flux to the locations at which mixing occurs. When confined to the tropical Atlantic, a robust single-basin circulation can be maintained, but the Indian and Pacific become quiescent, cut off from the dynamics occurring in the Atlantic. Mixing isolated in the tropical Pacific, however, can support a global circulation by mechanically lifting deep fluid parcels formed in the Atlantic, raising their potential energy. / (cont.) The oceans' total heat flux is found to be sensitive to mixing in the tropics, in both the Atlantic and the Pacific, and in the upper 400 meters of the ocean. Coupling mixing with a measure of tropical cyclone intensity and frequency creates a positive feedback between climate and the poleward energy flux. When combined with a parameterization of the background mixing that evolves with stratification, a warmer, less stratified ocean can support a stronger diapycnal mixing during warm climates with high loads of carbon dioxide. In these simulations, tropical cyclones are stronger and more frequent, providing an increased energy source for more vigorous mixing in the tropical oceans. Combined with a stratification-dependent mixing scheme, such mixing provides a sufficiently strong heat flux that is able to maintain weak sea surface temperature gradients. / by Robert Lindsay Korty. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997. / Includes bibliographical references (leaves 69-77). / by Daniel Lizarralde. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Bibliography: leaves 598-622. / by William Joseph Pegram. / Ph.D.