Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998. / Includes bibliographical references (leaves 63-66). / The two latest generations of MPI ECHAM AGCMs, ECHAM3 and ECHAM4, have been performed the test run in relatively high resolution (T106) with the prescribed AMI boundary conditions. There are major changes made in ECAHM4 T106 from ECHAM3 T106 in the radiation scheme, the treatment of radiation absorption by water vapor and cloud water and the calculation methods of advection of water vapor and cloud water, etc. It is shown that the simulation of annual mean heat balance at ocean surface has been greatly improved in ECHAM4 T106 with respect to the GEBA observations. While the annual mean state is important to the global climate system's heat and water balance, the distribution of global heat and water divergence determines the energy and water mass transport in the atmosphere and between the ocean and atmosphere. The diagnostic studies of ECHAM AGCMs' implied oceanic meridional heat transport and their comparison with available observational data, and the break-down of model annual surface heat balance terms highlight the importance of model's treatment in radiation absorption of atmospheric water vapor, the cloud radiation forcing calculation and latent heat contribution from hydrological balance requirement. The ECHAM GCMs' response with the ocean-atmosphere boundary condition is also investigated with MIT's ECHAM4 T42 datasets, which are obtained with the two different boundary conditions. The ECHAM4 model is capable in simulating the annual mean implied oceanic meridional heat transport with fare accuracy in T42 resolution, while the interannual variation is clearly shown. / by Ji-yong Wang. / S.M.

Thesis: Ph. D. in Planetary Sciences, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 183-200). / With over 1800 planets discovered outside of the Solar System in the past two decades, the field of exoplanetology has broadened our perspective on planetary systems. Research priorities are now moving from planet detection to planet characterization. In this context, transiting exoplanets-planets that cross in front of their star from our point-of-view-are of special interest due to the wealth of data made available by their orbital configuration. In this thesis, I introduce two methods, and their Markov chain Monte Carlo implementations, to gain new insights into the atmospheric and interior properties of exoplanets. The first method aims to map an exoplanet's atmosphere based on the eclipse scanning which is obtained while a planet is occulted by its host star. Ultimately temperature, composition, and circulation patterns could be constrained in three-dimensions from these maps, a significant asset for informing atmospheric models. I introduce the basics of eclipse mapping, its caveats (particularly, the correlation between the planet's shape, brightness distribution, and four system parameters), and a framework to mitigate the caveats' effects via global analyses including transits, phase curves, and radial velocity measurements. I use this method to create the first two-dimensional map and the first cloud map of an exoplanet for the hot-Jupiters HD 189733b and Kepler-7b, respectively. The second method, MassSpec, aims to determine transiting planet masses and atmospheric properties solely from transmission spectra, i.e. the starlight filtered by a planet's atmosphere during transits. Determination of an exoplanet's mass is key to understanding its basic properties, including its potential for supporting life. To date, mass constraints for exoplanets are predominantly based on radial velocity measurements, which are not suited for planets with low masses, large semi-major axes, or those orbiting faint or active stars. I demonstrate that a planet's mass has to be accounted for by atmospheric retrieval methods to ensure unbiased estimates of atmospheric properties. Utilizing MassSpec, the James Webb Space Telescope (launch date: 2018) could determine the mass and atmospheric properties of half a dozen Earth-sized planets in their host's habitable zones over its lifetime, which could lead to the first identification of a habitable exoplanet. / by Julien de Wit. / Ph. D. in Planetary Sciences

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 211-219). / by Yuexin Liu. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 117-124). / by Beverly Z. Saylor. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, February 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 65-69). / In this work we apply the method of two-dimensional time-lapse electrical resistivity tomography (2D time-lapse ERT) for two different problems. In the first problem, we monitor the structural stability of the roof of the Great Hall cavern in the Harrison's cave system, Barbados. We present an interpretation and comparison of two sets of resistivity data collected over the Great Hall: one set collected by us in 2010, the other in 1996. Our results show that fracturing and degradation had progressed since 1996, indicating a gradual weakening of the structural stability of the roof of the Great Hall cavern. In the second problem, we conduct 2D ERT surveys during dry and rainy seasons to evaluate the potential and feasibility of groundwater exploration next to the Thomazo River in the Fond D'Or watershed in Saint Lucia. Interpretation of the ERT data sets reveals a lens of a porous rock that has a high potential to be a productive aquifer. We use the ERT time-lapse approach to evaluate the change in water content between dry and wet seasons in the potential aquifer. / by Yulia Agramakova. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009. / Includes bibliographical references (p. 55-60). / Layered deposits atop both Martian poles are thought to preserve a record of past climatic conditions in up to three km of water ice and dust. Just beyond the extent of these south polar layered deposits (SPLD), dozens of impact craters contain large mounds of fill material with distinct similarities to the main layered deposits. Previously identified as outliers of the main SPLD, these deposits could offer clues to the climatic history of the Martian south polar region. We extend previous studies of these features by cataloging all crater deposits found near the south pole and quantifying the physical parameters of both the deposits and their host craters. Using MOLA topography data, MOC and THEMIS imagery, and SHARAD radar sounding data, we characterize the distribution, morphology, and structure of the deposits. In addition, we examine the effect of the crater microenvironment on the formation and persistence of these deposits, exploring the relative importance of solar and eolian processes in shaping their present-day distribution and appearance. We consider the possibility that crater sand dunes may have promoted ice accumulation over time and weigh various explanations for the origins and larger climatic significance of these features. / by Own William Westbrook. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994. / Includes bibliographical references (p. 113-117). / by Leslie Ann Young. / Ph.D.

Thesis (S.M. in Atmospheric Science)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 79-84). / I postulate that a diurnal cycle may exist in observational variables related to tropical cyclone (TC) intensity. Prior studies document a significant diurnal signal in moist convection across tropical regions. Since convection becomes more pronounced in intense TCs, daily solar insolation possibly affects observed TC intensities. What remains unclear is if the diurnal signals in physical influences, or factors that modulate TC intensity over hourly timescales, are also prominent in observed TC intensity fields. We apply various analytical techniques to two TC datasets and uncover a slight, yet detectable, diurnal trend in some calculated intensity fields. We first calculate 6-h maximum sustained surface wind (MSSW) tendencies using Atlantic TC best-track data from the National Oceanic and Atmospheric Administration (NOAA) National Hurricane Center (NHC) over years 1967-2011. In addition, we separate land tracks from warm-water tracks to analyze diurnal departures from the background states of these physical situations. We obtain a mid to late morning maximum in rapid intensification (RI) events over warm water. No discernible trend exists for land-filling TCs, even after using the decay model of Kaplan and DeMaria (1995) to find diurnal departures from mean decay rates. We also calculate theoretical TC indices using Atlantic TC dropsonde data from NOAA NHC over years 2002-2005 and 2011-2012. The indices, which measure physical influences on TC intensity, shift significantly during morning hours. This trend includes higher potential intensity (PI) and lower ventilation during late morning. The diurnal signal in RI frequency and intensity indices follows prior statistics and two physical mechanisms. The signal's greater PI coincides with more frequent occurrences of RI events, as confirmed statistically for Atlantic TCs by Kaplan and DeMaria (2003). Data noise likely obscures a possible diurnal signal in the negative MSSW tendencies analyzed in our study. Large-scale mechanisms that support our observed diurnal signal include enhanced radiatively driven low-level convergence and mid-level moisture during morning hours. / by Roman S. Kowch. / S.M.in Atmospheric Science

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990. / Includes bibliographical references (p. 183-192). / by John William Nielsen. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994. / Includes bibliographical references (p. 127-131). / by Paula Jean Waschbusch. / Ph.D.