Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008. / Includes bibliographical references (p. 115-127). / A modern general circulation model of the Southern Ocean with one-sixth of a degree resolution is optimized to the observed ocean in a weighted least squares sense. Convergence to the state estimate solution is carried out by systematically adjusting the control variables (atmospheric state and initial conditions) using the adjoint model. A cost function compares the model state to in situ observations (Argo float profiles, CTD synoptic sections, SEaOS instrument mounted seal profiles, and XBTs), altimetric observations (ENVISAT, GEOSAT, Jason, TOPEX/Poseidon), and other data sets (e.g. infrared and microwave radiometer observed sea surface temperature and NSIDC sea-ice concentration). Costs attributed to control variable perturbations ensure a physically realistic solution. The state estimate is found to be largely consistent with the individual observations, as well as with integrated fluxes inferred from previous static inverse models. The transformed Eulerian mean formulation is an elegant way to theorize about the Southern Ocean. Current researchers utilizing this framework, however, have been making assumptions that render their theories largely irrelevant to the actual ocean. It is shown that theories of the overturning circulation must include the effect of pressure forcing. This is true in the most buoyant waters, where pressure forcing overcomes eddy and wind forcing to balance a poleward geostrophic transport and allows the buoyancy budget to be closed. Pressure forcing is also lowest order at depth. Indeed, the Southern Ocean's characteristic multiple cell overturning is primarily in geostrophic balance. Several other aspects of the Southern Ocean circulation are also investigated in the thesis, including an analysis of the magnitude and variability of heat, salt, and volume inter-basin transports. / by Matthew R. Mazloff. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography : leaves 106-113. / by Richard Limeburner. / M.S.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Vita. / Bibliography: leaves 122-129. / by Harry Leonard Bryden, Jr. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography : leaves 45-48. / by Clare Bertram Billing, Jr. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography : leaves 89-90. / by Daniel Golan. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography : leaf 80. / by John Lee Lillibridge III. / M.S.

In this thesis, I explore the climate system's response to symmetric abrupt and transient CO₂ forcing across a range of concentrations, from ⅛ ⨉ to 8⨉CO₂, relative to pre-industrial levels. I use two CMIP6 class models: the CESM Large Ensemble (CESM-LE) model configuration and the NASA Goddard Institute for Space Studies Model E2.1-G (GISS-E2.1-G). I use a hierarchy of (1) fully coupled atmosphere-ocean-sea-ice-land, (2) slab ocean, and (3) prescribed sea surface temperature simulations to analyze and support the findings. First, I find an asymmetric response in global mean surface air temperature (𝚫𝜯_s) and effective climate sensitivity (EffCS) between colder and warmer experiments. The 𝚫𝜯_s response at 8⨉CO₂ is more than a third larger than the corresponding cooling at ⅛⨉CO₂. I attribute this assymetry primarily due to the non-logarithmic CO₂ forcing, not to changes in the radiative feedbacks. Second, I identify a non-monotonic response of EffCS in the warmer scenarios, with a minimum occurring at 4⨉CO₂ (3⨉CO₂) in CESM-LE (GISS-E2.1-G). This minimum in the warming simulations is associated with a non-monotonicity in the radiative feedback. Similar non-monotonic responses in Northern Hemisphere sea-ice, precipitation, the latitude of zero precipitation-minus-evaporation, and the strength of the Hadley cell are also identified. Comparing the climate response over the same CO₂ range between fully coupled and slab-ocean versions of the same models, I demonstrate that the climate system’s non-monotonic response is linked to changes in ocean dynamics, associated with a collapse of the Atlantic Meridional Overturning Circulation (AMOC). Third, to establish the significance of North Atlantic cooling in driving the non-monotonic changes in the radiative feedback, I conducted additional atmosphere-only (AMIP) simulations using the same models but with prescribed sea surface temperatures (SSTs) restricted to different regions. Through these simulations, I uncovered that the minimum EffCS value, characterized by notably negative radiative feedbacks, primarily originates from relative cooling of the sea surface temperature (SST) in the tropical and subtropical North Atlantic. This cooling of SSTs contributes to an increase in low-level cloud content in the eastern region of the North Atlantic, subsequently leading to a pronounced negative (stabilizing) feedback response. Furthermore, I investigated the state dependence of the effective radiative forcing (ERF) from 1/16 ⨉ to 16⨉CO₂. I found that ERF increases with CO₂ concentration due to the increase in Instantaneous Radiative Forcing (IRF). Specifically, the IRF increases at higher CO₂ values primarily due to stronger stratospheric cooling induced by CO₂ forcing. On the other hand, the radiative adjustments counteract the IRF increase, causing the ERF to rise at a slower pace compared to the corresponding increase in IRF induced by higher CO₂ concentrations. Lastly, I studied the winter storm tracks in the Southern Hemisphere, focusing on experiments up to 8⨉CO₂. Through this analysis, I identified a non-linear response in the low latitude storm tracks. It is projected that the storm tracks will experience an intensification by the end of the century. However, my findings reveal that this intensification does not scale linearly with CO₂ forcing. In fact, the storm tracks shift poleward, including a reduction of the storm tracks at low-mid latitudes and intensification at mid-high latitudes.

Geoscience applications generate large datasets; thus, compression is necessary to facilitate the storage and transmission of geoscience data. One focus is on the coding of hyperspectral imagery and the prominent JPEG2000 standard. Certain aspects of the encoder, such as rate-allocation between bands and spectral decorrelation, are not covered by the JPEG2000 standard. This thesis investigates the performance of several JPEG2000 encoding strategies. Additionally, a relatively low-complexity 3D embedded wavelet-based coder, 3D-tarp, is proposed for the compression of geoscience data. 3D-tarp employs an explicit estimate of the probability of coefficient significance to drive a nonadaptive arithmetic coder, resulting in a simple implementation suited to vectorized hardware acceleration. Finally, an embedded wavelet-based coder is proposed for the shapeaptive coding of ocean-temperature data. 3D binary set-splitting with $k$-d trees, 3D-BISK, replaces the octree splitting structure of other shapeaptive coders with $k$-d trees, a simpler set partitioning structure that is well-suited to shapeaptive coding.

No description available.

Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social impact of tropical cyclones, it is important to investigate how an Atlantic-Indian Ocean connection may be affecting tropical cyclone behavior in the southern Indian Ocean. In this study, the International Best Track Archive for Climate Stewardship (IBTrAC) tropical cyclone database is used to derive metrics of tropical cyclone behavior, which are then compared with indices of tropical Atlantic SST variability representing Atlantic Niño, and Benguela Niño events. Changes in tropical Atlantic SSTs are found to coincide with significant differences in tropical cyclone activity for portions of the southern Indian Ocean. In addition, for these same regions, tropical Atlantic SST variability is associated with changes in large-scale atmospheric conditions, including steering flow, low level vorticity, and humidity, typically associated with tropical cyclogenesis, and tropical cyclone track. The changes in steering flow related to both indices of Atlantic SST anomaly are reproduced by an atmospheric model. The changes in steering flow are also found to be linked to changes in TC translational velocity, and TC tracking. These findings indicate a possible link between tropical Atlantic conditions and cyclone activity in the Indian Ocean mediated through a teleconnection between tropical Atlantic SSTs and large scale atmospheric conditions over the southern Indian Ocean. The teleconnection related to the Benguela Niño region of SST variability was found to consist of a Rossby wave initiated off the coast of South America, and propagating into the Indian Ocean, thereby influencing several atmospheric variables, including steering flow. The teleconnection related to the Atlantic Niño region of SST variability was not well defined, although there was some evidence of a Walker circulation anomaly extending from the equatorial Atlantic over the continent of Africa, and influencing SIO steering flow. / Graduation date: 2012