Thesis (Ph. D.)--University of Wisconsin--Madison, 1987. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 152-157).

Thesis (Ph. D.)-- University of Washington, 2004. / Vita. Includes bibliographical references (leaves 242-251).

Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 2, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Earth and Atmospheric Sciences, University of Alberta. Includes bibliographical references.

Convective cold pools are important modulators of the onset and evolution of deep convection in the tropics. Cold pools are generated by downdrafts and can outlive the storms they originate from to spark new convection. However, most of our understanding of cold pool mechanics comes from high-resolution simulations and a relatively small number of in situ observational studies. This thesis brings novel observational approaches together with climate model data to understand the behavior of cold pools on a global scale and how a mesoscale weather behavior can be accounted for in a climate-scale simulation. First, we leverage a dataset derived from the Advanced Scatterometer (ASCAT) satellite instrument by Garg et al. (2020) to quantify seasonal variations in cold pool activity and their relationship to deep convection across tropical ocean basins. The dataset identifies gradient features (GFs) in the surface wind field, which have been shown to serve as reliable proxies for the boundaries of atmospheric cold pools. We examine the relationship between GFs and climatologies of precipitation, column relative humidity (CRH), and bulk vertical wind shear. We also collocate GFs with precipitation and CRH. High GF frequency, precipitation, and CRH coincide in many regions of the tropics, consistent with our understanding of the physical connections between precipitation and cold pool generation. On the other hand, climatological bulk wind shear is often low in convective regions, and there is a weak inverse correlation between GF frequency and bulk wind shear, while our prior expectation might have been that shear promotes cold pool formation. Compared to GF frequency, GF size shows a weaker relationship with the convective environment, with some of the largest GFs occurring at lower CRH values for a given rainfall rate. In a few exceptional regions and seasons, such as the Indian Ocean in northern hemisphere summer, the region of greatest precipitation does not coincide with the region of greatest GF frequency. These cases also have very high seasonal mean CRH, suggesting that in these regions cold pool formation is suppressed by reduced evaporation of precipitation. Following that, we apply the GF data set to the task of evaluating the realism of the cold pool parameterization in the GISS E3 earth model originally designed by Del Genio et al. (2015). We compare the GF data set to model results from six versions of the GISS model with perturbed parameters. Cold pools generated by the model have significantly different geographic distribution to satellite-observed GFs, particularly in critical convective regions. They also appear to be much less common than GFs, though they have a broadly similar dependence on column water vapor (CWV), especially in terms of size. Finally, we seek to understand the mechanics of the model cold pool parameterization on its own. A subset of high-time resolution model versions is used to deconstruct the behavior of the model parameterization at the scale of individual time steps. Our aim is to see what level of physical realism is associated with the emergent trends seen in the climatological statistics. We find that the model generates cold pool temperature and moisture depressions of similar magnitude to cold pools measured from ships, but tend to dissipate too quickly. Model cold pools also appear to spark increased precipitation, as they are designed to do, but that precipitation appears to come from the stratiform model parameterization, not the moist convection one. Together, these results provide a first opportunity to empirically evaluate a model parameterization originally developed using theory.

Water vapour is the principle source of opacity at infrared wavelengths in the Earth’s atmosphere. In support of site testing for the European Extremely Large Telescope (E-ELT), we have used La Silla and Paranal as calibration sites to verify satellite measurements of precipitable water vapour (PWV). We reconstructed the PWV history over both sites by analysing thousands of archived high-resolution echelle calibration spectra and compared that to satellite estimates for the same period. Three PWV measurement campaigns were conducted over both sites using several independent measurement techniques. Radiosondes were launched to coincide with satellite measurements and provide a PWV reference standard allowing intercomparison between the various instruments and methods. This multi-faceted approach has resulted in a unique data set. Integral to this analysis is the internal consistency provided by using a common atmospheric model. / xvii, 206 leaves : ill. (some col.) ; 28 cm

Cheng, Shilai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 138-150). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

This study examines the long-term record of lower stratospheric water vapor focusing on the 20-year data record from the Stratospheric Aerosol and Gas Experiment II (SAGE II). The SAGE II zonal monthly mean water vapor data was enhanced to include the aerosol heavy late 1980s through the use of aerosol extinction filtering of the data. Comparisons between the SAGE II lower stratospheric water vapor and the Limb Infrared Monitor of the Stratosphere (LIMS), the Microwave Limb Sounder (MLS), and HALogen Occultation Experiment (HALOE) are performed. This study further focuses on the minimum lower stratospheric water vapor (i.e., hygropause) and on the dehydration seen in the hygropause with examination of the transport barrier at both the tropical tropopause and the tropopause folding region between the tropics and extra-tropics that would account for this decadal variation. The effects of aerosol contamination on the SAGE II water vapor retrievals from four volcanic eruptions from 1984 to 1992 were examined, leading to a four level filtering of the SAGE II water vapor data to allow retention of good data from early in the data record. With the improved filtered water vapor data, monthly and seasonal time series analyses show a significant decadal variation in the lower stratosphere for all months where the satellite coverage provided data from the late 1980s to the early 2000s. This decadal variation documents a decrease in the water vapor from below approximately 25 km to below the tropopause with this decrease seen in the hygropause from the tropics to the poles. Analysis of the hygropause for all months provided a statistically significant consistent neutral or decreasing value in the long-term water vapor minimum. March was shown to be the seasonal minimum in the hygropause over this 20-year low aerosol record, followed by a discontinuity in the minimum abundance after 2000. Three transport pathways for transport of water vapor from the moist troposphere to the lower stratosphere include the tropical tropopause, isentropic transport at the sub-tropical jet locations, and meridional transport from the tropics to the midlatitudes above the hygropause. The tropical tropopause temperatures were examined using the new Modern Era Retrospective-analysis for Research and Applications (MERRA) data set. Analysis showed a significant decrease in the tropical and sub-tropical tropopause temperatures over the 20-year timeframe for the DJF season preceding the March minimum. The lower temperatures would provide a colder "cold trap" at the tropopause, further "freeze drying" the air seasonally transported from the upper troposphere to the lower stratosphere, providing the long-term dehydration in the hygropause and lower stratosphere. The Ertel's Potential Vorticity (EPV or PV) was examined as a proxy for the sub-tropical jet movement towards the poles over this long-term record. Changes in this pathway location may affect the efficiency of isentropic transport of moist tropospheric air into the lower stratosphere at these higher latitudes. Analysis using the MERRA zonal EPV and maximum zonal Uwind data showed a statistically significant shift in the locations of the contours towards the SH poles over this 20-year timeframe for the DJF, DJFM seasons and the month of December. The meridional winds above the tropopause show an increase over the 20-year record covered by SAGE II water vapor data. These increasing winds are consistent with the increase in the Brewer-Dobson circulation shown in other studies. The colder tropopause temperatures along with the increasing Brewer-Dobson circulation just above the tropopause, are the likely cause for the decreasing water vapor trend as seen in the SAGE II March hygropause over the 20-years from 1986-2005.

This research has involved the conduct of a series of laboratory measurements of the centimeter-wavelength opacity of water vapor along with the development of a hybrid radiative transfer ray-tracing simulator for the atmosphere of Jupiter which employs a model for water vapor opacity derived from the measurements. For this study an existing Georgia Tech high-sensitivity microwave measurement system (Hanley and Steffes , 2007) has been adapted for pressures ranging from 12-100 bars, and a corresponding temperature range of 293-525°K. Water vapor is measured in a mixture of hydrogen and helium. Using these measurements which covered a wavelength range of 6--20 cm, a new model is developed for water vapor absorption under Jovian conditions. In conjunction with our laboratory measurements, and the development of a new model for water vapor absorption, we conduct sensitivity studies of water vapor microwave emission in the Jovian atmosphere using a hybrid radiative transfer ray-tracing simulator. The approach has been used previously for Saturn (Hoffman, 2001), and Venus (Jenkins et al., 2001). This model has been adapted to include the antenna patterns typical of the NASA Juno Mission microwave radiometer (NASA/Juno -MWR) along with Jupiter's geometric parameters (oblateness), and atmospheric conditions. Using this adapted model we perform rigorous sensitivity tests for water vapor in the Jovian atmosphere. This work will directly improve our understanding of microwave absorption by atmospheric water vapor at Jupiter, and improve retrievals from the Juno microwave radiometer. Indirectly, this work will help to refine models for the formation of Jupiter and the entire solar system through an improved understanding of the planet-wide abundance of water vapor which will result from the successful opreation of the Juno Microwave Radiometer (Juno-MWR).

The present study contains a calculation and discussion of meridional advection of water vapour on a daily basis across three latitude circles (65°N., 70°N., 80°N.) for the months of January and July, 1958. [...]

The performance of astronomical interferometer arrays operating at (sub) millimeter wave-lengths is seriously compromised by rapid variations of atmospheric water vapour content that distort the phase coherence of incoming celestial signals. Unless corrected, these phase distortions, which vary rapidly with time and from antenna to antenna, seriously compromise the sensitivity and image quality of these arrays. Building on the success of a prototype infrared radiometer for millimeter astronomy (IRMA I), which was ued to measure atmospheric water vapour column abundance, this thesis presents results from a second generation radiometer (IRMA II) operating at the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii from December, 2000 to March, 2001. These results include comparisons with other measures of water vapour abundance available on the summit of Mauna Kea and a comparison with a theorteical curve-of-growth calculated from a new radiative transfer model, ULTRAM, developed specifically for the purpose. Plans for a third generation radiometer (IRMA III) are also be discussed. / xii, 143 leaves : ill. ; 28 cm.