Thesis (Ph. D.)--North Carolina State University, 1985. / Vita. Includes bibliographical references (p. 66-67).

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 186-196). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNR11559

One of the defining characteristics of hotspot volcanism is the presence of a long-lived, linear chain of age-progressive volcanoes created by the movement of the lithosphere over a stationary melting anomaly. However, the spatial distribution of volcanism at hotspots is often complex and highly variable suggesting that the relationship between magma generation and magma transport at hotspots is poorly understood. Here, I present the results of the first systematic quantitative characterization of the spatial distribution of volcanism at oceanic hotspots. In the first study I develop a novel methodology to characterize the across-strike distribution of volcanism at hotspots and apply it to a catalog of 40 oceanic hotpots. I find that only 25% (10/40) of hotspots exhibit the simple single-peak profile predicted by geodynamic models of melt generation in mantle plumes. The remaining 75% (30/40) of hotspots exhibit a dual- or multi-peak pattern. In the second study, I focus on the across-strike distribution of volcanism at the oceanic hotspots that are sourced by a deep-rooted mantle plume. 14 out of the 15 consensus plume-fed hotspots exhibit a dual-peaked across-strike profile. The spacing between these peaks display a strong negative correlation with lithospheric age, in direct contrast to models of inter-volcanic spacing controlled by elastic plate thickness. This relation suggests a different mechanism controls volcanic spacing at plume-fed hotspots. In the third chapter, I investigate variations in the average topographic profiles over time along the two longest and best-constrained oceanic hotspot tracks: Hawaii and Louisville. I find that the dual-peak across-strike profile of volcanism is a persistent feature at the Louisville hotspot over the entire length of the track examined (spanning a period of more than 65 Myr). In contrast, the dual-peak profile of volcanism at Hawaii is only evident along the most recent portion of the track (i.e., over the last 5 Myr). In total, this thesis represents a significant step foreword in the collective understanding of hotspot volcanism, and introduces a new diagnostic tool for analysis of hotspot influenced seafloor topography.

Thesis (doctoral)--Johann Wolfgang Goethe Universität, 2004. / Includes bibliographical references (p. [270]-299).

No description available.

No description available.

The retrieval of an aerosol scattering phase function using a multi-satellite technique is proposed. A total of 33 phase functions were derived from 18 smoke cases and 15 dust cases. Each case was interrogated using four to nine satellite passes over the aerosol in a two to four hour time frame. The radiance values for the Red and Near-Infrared (NIR) channels were combined with backscattering angles to determine the shape of the scattering phase function. The radiance values were input into the Naval Postgraduate School (NPS) aerosol model to determine optical depths and sample phase functions. A comparison was made between the actual phase functions retrieved and the NPS model phase functions. It was found that the phase functions for the smoke cases more closely matched the model phase functions than in the dust cases. Some conclusions could be drawn about the actual aerosol size and density distribution based on how well it matched the model phase function. Further analysis is necessary to define the exact size and number of the aerosol particles. Fully understanding the aerosol composition is crucial in determining its effects on military sensors and impacts to operations.

Xi Hengdong = 關於熱羽流和Rayleigh-Bénard對流中大尺度環流形成的實驗研究 / 郗恒東. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 71-75). / Text in English; abstracts in English and Chinese. / Xi Hengdong = Guan yu re yu liu he Rayleigh-Bénard dui liu zhong da chi du huan liu xing cheng de shi yan yan jiu / Xi Hengdong. / Table of Contents --- p.v / List of Figures --- p.xi / List of Tables --- p.xii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rayleigh-Benard System --- p.1 / Chapter 1.1.1 --- Physical Picture --- p.1 / Chapter 1.1.2 --- Characteristic Parameters --- p.2 / Chapter 1.2 --- Plume and Large Scale Circulation --- p.4 / Chapter 2 --- Experimental Setup and Techniques --- p.8 / Chapter 2.1 --- Apparatus --- p.8 / Chapter 2.1.1 --- Convection Cell --- p.8 / Chapter 2.1.2 --- Other Apparatus --- p.12 / Chapter 2.2 --- Visualization --- p.14 / Chapter 2.3 --- PIV technique --- p.17 / Chapter 2.3.1 --- Image Capture System --- p.20 / Chapter 2.3.2 --- Image Analysis system --- p.26 / Chapter 3 --- Properties of Laminar Plume --- p.30 / Chapter 3.1 --- Shadowgraph and Temperature measurement --- p.30 / Chapter 3.2 --- Velocity Measurement --- p.35 / Chapter 4 --- Onset of Large-scale circulation in turbulent thermal convec- tion --- p.48 / Chapter 5 --- Convection in Rectangular cell --- p.60 / Chapter 6 --- Conclusion --- p.69 / Chapter 6.1 --- Conclusion --- p.69 / Chapter 6.2 --- Perspective for further investigation --- p.71 / Bibliography --- p.72

Plumes are formed when a continuous buoyant forcing is supplied at a localized source. Buoyancy can be created by either a heat flux, a compositional difference between the fluid coming from the source and its surroundings, or a combination of both. In this thesis, two types of laminar plumes with different forcing mechanisms were investigated: forced plumes and autocatalytic plumes. The forced plumes were compositionally buoyant and were injected with inertial forcing into a fluid filled tank. The autocatalytic plumes were produced without mechanical forcing by buoyancy that was entirely the consequence of a nonlinear chemical reaction -- the iodate-arsenous acid (IAA) reaction. This reaction propagates as a reacting front and produces buoyancy by its exothermicity, and by the compositional difference between the reactant and product. Both the forced and autocatalytic plumes were examined in starting and steady states. The starting, or transient, state of the plume occurs when it initially rises through a fluid and develops a plume head on top of a trailing conduit. The steady state emerges after the plume head has risen to the top of a fluid filled tank leaving only a persistent conduit. Plume behaviour was studied through experimentation, simulation, and by using simple theoretical analysis. We performed the first ever study of plumes as they crossed over the transition between buoyancy-driven to momentum-driven flow. Regardless of the driving mechanism, forced plumes were found to exhibit a single power law relationship that explains their ascent velocity. However, the morphology of the plume heads was found to depend on the dominating driving mechanism. Confined heads were produced by buoyancy-driven plumes, and dispersed heads by momentum-driven plumes. Autocatalytic plumes were found to have rich dynamics that are a consequence of the interplay between fluid flow and chemical reaction. These plumes produced accelerating heads that detached from the conduit, forming free vortex rings. A second-generation head would then develop at the point of detachment. The detachment process for plumes was sensitively dependent on small fluctuations in their initial formation. In some cases, head detachment could occur multiple times for a single experimental run, thereby producing several generations of autocatalytic vortex rings. Head detachment was reproduced and studied using autocatalytic plume simulations. Autocatalytic flame balls, a phenomenon closely related to autocatalytic plumes, were also simulated. Flame balls were found to have three dynamical regimes. Below a critical radius, the smallest flame balls experienced front death. Above this radius, they formed elongating, reacting tails. The largest flame balls formed filamentary tails unable to sustain a reaction.

Plumes are formed when a continuous buoyant forcing is supplied at a localized source. Buoyancy can be created by either a heat flux, a compositional difference between the fluid coming from the source and its surroundings, or a combination of both. In this thesis, two types of laminar plumes with different forcing mechanisms were investigated: forced plumes and autocatalytic plumes. The forced plumes were compositionally buoyant and were injected with inertial forcing into a fluid filled tank. The autocatalytic plumes were produced without mechanical forcing by buoyancy that was entirely the consequence of a nonlinear chemical reaction -- the iodate-arsenous acid (IAA) reaction. This reaction propagates as a reacting front and produces buoyancy by its exothermicity, and by the compositional difference between the reactant and product. Both the forced and autocatalytic plumes were examined in starting and steady states. The starting, or transient, state of the plume occurs when it initially rises through a fluid and develops a plume head on top of a trailing conduit. The steady state emerges after the plume head has risen to the top of a fluid filled tank leaving only a persistent conduit. Plume behaviour was studied through experimentation, simulation, and by using simple theoretical analysis. We performed the first ever study of plumes as they crossed over the transition between buoyancy-driven to momentum-driven flow. Regardless of the driving mechanism, forced plumes were found to exhibit a single power law relationship that explains their ascent velocity. However, the morphology of the plume heads was found to depend on the dominating driving mechanism. Confined heads were produced by buoyancy-driven plumes, and dispersed heads by momentum-driven plumes. Autocatalytic plumes were found to have rich dynamics that are a consequence of the interplay between fluid flow and chemical reaction. These plumes produced accelerating heads that detached from the conduit, forming free vortex rings. A second-generation head would then develop at the point of detachment. The detachment process for plumes was sensitively dependent on small fluctuations in their initial formation. In some cases, head detachment could occur multiple times for a single experimental run, thereby producing several generations of autocatalytic vortex rings. Head detachment was reproduced and studied using autocatalytic plume simulations. Autocatalytic flame balls, a phenomenon closely related to autocatalytic plumes, were also simulated. Flame balls were found to have three dynamical regimes. Below a critical radius, the smallest flame balls experienced front death. Above this radius, they formed elongating, reacting tails. The largest flame balls formed filamentary tails unable to sustain a reaction.