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.

vii, 200 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1989

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [121]-127).

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 110 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 90-91).

Thesis (M.S.)--Rowan University, 2006. / Typescript. Includes bibliographical references.

Thesis (M.S.)--Washington State University, May 2006. / Includes bibliographical references (p. 81-83).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Keenan A. Pituch. Vita. Includes bibliographical references.

Undergraduate honors paper--Mount Holyoke College, 2007. Dept. of Mathematics and Statistics. / Includes bibliographical references (leaves 81-82).

The Planck cosmic microwave background temperature data are best fit with a Lambda CDM model that mildly contradicts constraints from other cosmological probes. The South Pole Telescope (SPT) 2540 deg(2) SPT-SZ survey offers measurements on sub-degree angular scales (multipoles 650 <= l <= 2500) with sufficient precision to use as an independent check of the Planck data. Here we build on the recent joint analysis of the SPT-SZ and Planck data in Hou et al. by comparing Lambda CDM parameter estimates using the temperature power spectrum from both data sets in the SPT-SZ survey region. We also restrict the multipole range used in parameter fitting to focus on modes measured well by both SPT and Planck, thereby greatly reducing sample variance as a driver of parameter differences and creating a stringent test for systematic errors. We find no evidence of systematic errors from these tests. When we expand the maximum multipole of SPT data used, we see low-significance shifts in the angular scale of the sound horizon and the physical baryon and cold dark matter densities, with a resulting trend to higher Hubble constant. When we compare SPT and Planck data on the SPT-SZ sky patch to Planck full-sky data but keep the multipole range restricted, we find differences in the parameters n(s) and A(s)e(-2 tau). We perform further checks, investigating instrumental effects and modeling assumptions, and we find no evidence that the effects investigated are responsible for any of the parameter shifts. Taken together, these tests reveal no evidence for systematic errors in SPT or Planck data in the overlapping sky coverage and multipole range and at most weak evidence for a breakdown of Lambda CDM or systematic errors influencing either the Planck data outside the SPT-SZ survey area or the SPT data at l > 2000.

Analytical models and simulations predict a rapid decline in the halo density profile associated with the transition from the "infalling" regime outside the halo to the "collapsed" regime within the halo. Using data from SDSS, we explore evidence for such a feature in the density profiles of galaxy clusters using several different approaches. We first estimate the steepening of the outer galaxy density profile around clusters, finding evidence for truncation of the halo profile. Next, we measure the galaxy density profile around clusters using two sets of galaxies selected on color. We find evidence of an abrupt change in galaxy colors that coincides with the location of the steepening of the density profile. Since galaxies that have completed orbits within the cluster are more likely to be quenched of star formation and thus appear redder, this abrupt change in galaxy color can be associated with the transition from single-stream to multi-stream regimes. We also use a standard model comparison approach to measure evidence for a " splashback"-like feature, but find that this approach is very sensitive to modeling assumptions. Finally, we perform measurements using an independent cluster catalog to test for potential systematic errors associated with cluster selection. We identify several avenues for future work: improved understanding of the small-scale galaxy profile, lensing measurements, identification of proxies for the halo accretion rate, and other tests. With upcoming data from the DES, KiDS, and HSC surveys, we can expect significant improvements in the study of halo boundaries.