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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1975. / Bibliography: leaves 178-182. / x, 182 leaves ill

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 204-208).

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 195-199).

This thesis describes observations of the flne structure in Jovian decametric radiation made at Grahamstown during the 1967-68 apparition. It was found that pulses with duration less than 0.5 milliseconds were common during fine structure storms. The restrictions placed on the source for different theories of origin of the short pulses are discussed. The variation of the probability of occurrence from year to year is analysed on the assumption that the radiation is found in directions fixed with respect to the planet's magnetic field. It is concluded that there is a factor other than the declination of Earth and the Io effect which controls the probability of occurrence. A detailed analysis suggests a beam width of 3° in latitude at Jupiter but further work is necessary to check this.

The silicate "magma trigger" model of volcanism on Io has been evaluated numerically with finite element methods by considering the one-dimensional heat transfer between hot silicate magma and initially cold sulfur. It is found that for the probable range of initial magma temperatures and sulfur temperatures, the contact between silicate magma and a sulfur crust will be 700 (+OR-) 100 K, or approximately the vapor point of elemental sulfur. A silicate magma sill or laccolith on the order of 10 m thick will yield energetic vapor for a period of several weeks to several months depending on the vapor temperature and the amount of convective cooling of the silicate magma that occurs at the silicate-sulfur interface. This model may account for the origin of plumes and possible sulfur flows, as well as for their observed temperatures ((TURN) 600-700K) and lifetimes (several days to a few months). If the conducted heat flow is similar in high and low latitudes, then the low latitude occurrence of plumes may be explained as a result of lower temperatures at higher latitudes. Because the contact temperature of sulfur and silicate magma depends on the pre-existing sulfur temperature, a system in which sulfur vapor temperature is just reached at the equator would not generate sulfur vapor under lower initial sulfur temperatures existing at high latitudes. If the heat flow is higher in high latitudes, then the sulfur crust must be thinner than it is in low latitudes for the model to work as described above. Most of the heat flow from Io may be moved by convection from the interior to the surface, not by conduction. Heat flow may be modulated by the efficient transfer of silicate melts from 40 to 300 km depth, and emplaced as laccoliths at the sulfur-silicate crustal interfaces at a depth of 5-10 km. Sulfur flows, plumes, calderas and other areas of massive radiant heat dissipation continue the convective cycle to the surface. The temperature at the base of the sulfur crust may be less than the melting point of sulfur, and the silicate magma temperature can be as low as 1200 K. Low silicate magma temperatures will occur if the crust of Io is as differentiated as terrestrial rhyolites and trachytes. High alkalies in the Io plasma torus suggest the possibility that the Ionian crust is a highly differentiated silicate.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 96-100).

Pioneer 10 and 11 polarimetry maps of Jupiter, taken at a wide variety of phase angles, have been analyzed. Data were reduced in two colors for Jupiter's South Equatorial Belt (latitude -5 to -8 degrees) and scattering models were constructed. Variations in polarization from center to limb set constraints on the vertical structure of the atmosphere. The absolute polarization near the center of the disc constrained the single scattering polarization phase matrix of the scattering particles. After exploring several types of cloud models, it was found that a two cloud model with a haze in the upper atmosphere fits the data best. Several types of vertical structures were ruled out, including gas over a nonpolarizing Lambert surface, gas over a polarizing cloud deck, uniformly mixed gas with scattering particles (Reflecting Scattering Model), and models where the cloud tops diffusely mixed with gas as a function of altitude. Constraints have been set upon the polarimetric scattering properties of the haze and lower clouds. The haze particles are closely approximated by conservatively scattering spheres of index of refraction 1.5 and uniformly distributed sizes between 0.16 and 0.18 microns radius. A relationship exists between the required index of refraction for the haze particles and the mean size of the particles. It is possible that the particles are more broadly distributed in size, as this area was not extensively explored. The optical depth of the haze is between 0.125 and 0.250 at a wavelength of 0.44 microns, and lies near the 200 millibar pressure level. The upper cloud, which is thought to be made of ammonia crystals, must be at least optical depth 2, and could be semi-infinite. The polarization scattering properties of the clouds are distinctly different from the haze, indicating a compositional or size difference. The cloud particles have polarizing properties indicative of large (larger than 0.5 micron radius) particles. The upper cloud has been modelled to be near the 500 millibar level, but the pressure level for the best fitting model depends upon the chosen single scattering phase matrix. For more negatively polarizing cloud particles, the cloud would be located deeper in the atmosphere. The lowest cloud is more weakly constrained. Its scattering properties are set the same as the upper cloud, and it has been modelled as having semi-infinite optical depth. For the nominal scattering phase matrix, this cloud is located near the 2250 millibar pressure level. The constraints set on both the vertical structure and the particle scattering properties can be useful in the determination of Jupiter's solar flux deposition profile. Additionally, the location of the cloud and haze layers in Jupiter's atmosphere is important to the understanding of the heat balance of the planet, as well as to the understanding of the global dynamic of Jupiter's atmosphere.