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.

No description available.

Simulations were performed to determine the effect of turbulence on protoplanets as they accrete inside of a planetary gas disk at the stage of planet formation that involves interactions between relatively large, similar sized bodies. The effect of turbulence was implemented into an existing N-Body code using a parameterization of magnetohydrodynamic (MHD) turbulence performed by Laughlin et. al. (2004). The investigation focussed on the effect of turbulent perturbations on planetary dynamics and accretion at various locations in the disk, particularly at large semimajor axis. At these distances, protoplanet collisions are generally less frequent due to the large induced eccentricities from close encounters and due to the trapping of protoplanets in mutual resonances. It is, however, essential that large protoplanets develop at these distances since some must eventually grow large enough to accrete the massive gas envelopes indicative of the giant planets. The interaction between a protoplanet and the surrounding gas disk creates a torque imbalance acting on the protoplanet, which is generally believed to result in the rapid inward spiraling of the protoplanet. In order to create a fixed region in the disk within which protoplanets may interact without migrating into the central star, two scenarios were considered that would inhibit the inward migration of the protoplanets. The first scenario involved a gas disk that had been truncated at the inner edge, referred to as a planet trap, and the second involved the existence of a stationary giant planet within a gap in the disk, referred to as a planet barrier. Each scenario was tested using different density profiles of the gas disk, different numbers and masses of initial protoplanets, various rates of gas disk decay and also four different levels of turbulence intensities. The results demonstrated that the addition of turbulence to the gas disk promotes planet mixing and results in an increased number of collisions between planets, even at large heliocentric distances. A turbulent disk has the tendency to create a final system where the planets are, on average, larger than those produced in a non-turbulent disk. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-17 14:41:52.607

No description available.

The Pioneer Venus Orbiter Infrared Radiometer and Venera 15 Fourier Transform Spectrometer observations of thermal emission from Venus' middle atmosphere between 10°S and 50°N were used to determine global maps of temperature, cloud optical depth and water vapour abundance. The spectral regions observed include the strong 15 μtm carbon dioxide band and the 45 μm fundamental rotational water band. The main aim of this thesis is to reconcile the water vapour abundance results from these two sets of observations reported in previous studies. New radiative transfer and retrieval models have been developed for this purpose based on new correlated-k absorption tables calculated with up-to-date spectral line data. The H₂SO₄ cloud opacity and scattering properties have been recalculated from new refractive index data using Mie theory. For the first time these two sets of observations have been analysed using the same retrieval tools. From the Pioneer Venus Orbiter Infrared Radiometer observations we report a high abundance of water vapour in the early afternoon at the equatorial cloud-top region and a strong day-night variability in the cloud-top pressure. From the Venera 15 Fourier Transform Spectrometer observations we report medium local variability in water vapour abundance, with highest values in the near-equatorial region and slight decrease towards the polar region. It is found that serious constraints are placed on the validation of the retrievals by the lack of adequately accurate H₂SO₄ optical properties data in the shorter wavelengths and by the poor vertical resolution when sensing the complex but interesting cloud region which prohibits its rigorous modelling. The proposed European Space Agency Venus Express mission will carry a number of high resolution infrared and UV instruments that will shed new light to the interesting question of water vapour abundance in Venus' middle atmosphere.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references. / Microfiche. / xiii, 161 leaves, bound ill. 29 cm

Thesis (Ph. D. in geology)--Washington State University, May 2008. / Includes bibliographical references.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 207-226). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19846

Diss. (sammanfattning) Luleå : Luleå tekniska univ., 2008. / Härtill 5 uppsatser.

Thesis (M.Sc.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 108-114). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19697