Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 153-162).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 121-129).

Occult deposition is the direct uptake of cloudwater by vegetation that comes into physical contact with wind-driven cloud droplets. This can be a significant pathway for hydrological and chemical fluxes from the atmosphere to some forests. Methods for estimating cloudwater fluxes to forests are reviewed. Previous studies have neglected the fact that cloudwater is not a conservative atmospheric quantity. This invalidates traditional micrometeorological approaches for estimation of cloudwater fluxes to forests. A theory is developed to predict the change in the cloudwater flux with height due to condensation in the updrafts of orographic cloud, allowing estimation of surface uptake via eddy correlation measurements while accounting for condensation. The performances of three microphysical instruments are examined. From collocated measurements, errors in cloud liquid water content are determined for a Particulate Volume Monitor (PVM) and a Forward Scattering Spectrometer Probe (FSSP) to be less than 0.01 g m⁻³ and 0.035 g m⁻³ respectively. Similarly, the error bounds for surface-normal cloud liquid water fluxes are found to be 2 mg m⁻² s⁻¹ for the PVM and 3.5 mg m⁻² s⁻¹ for the FSSP. Smaller errors are found to be associated with the uncertainty in the direction of the flux relevant to surface uptake. The FSSP is seen to have larger errors when droplet concentrations exceed 600 cm⁻³. A vertical divergence is detected in the cloudwater flux; the downward flux decreases with increasing distance from the surface, usually changing sign by 15 m above ground. Five candidate processes are identified as possible explanations for this measured flux divergence. A scale analysis shows that the liquid water source (condensation due to pseudoadiabatic ascent) is largely responsible for the change in flux with height. Accounting for the change in flux with height results in a near doubling of the estimated surface flux relative to the flux measured at a height of 10 m in the surface layer for this silver fir forest. This factor applies to chemical as well as liquid water fluxes. This source of liquid water also is seen to be important in developing a simple model for cloudwater deposition. / Graduation date: 1997

Typescript. / Theses (Ph. D.)--University of Hawaii at Manoa, 1978. / Bibliography: leaves 85-89. / Microfiche. / viii, 89 leaves ill

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 188-201). 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:NR19810

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 260-268). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNR11542

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 102-104).

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 146-152. / Ph.D.

The potential of a condensate method for sampling atmospheric trace gases is investigated. A theoretical approach to the collection of condensate by a cooled surface is presented, followed by an experimental procedure and verification of the method. Heat and mass transfer problems are solved to give distributions of temperature, velocity and mass concentration. From these distributions, collection rates for water vapor, trace gases, and particulates are derived. It is shown that the collection of particulates is negligible in most cases when compared to the collection of gases in the condensate; highly soluble gases are sampled with the greatest efficiency. Experimentally, a plate, cooled to below the ambient dew point temperature, collected condensate which was subsequently analyzed for various components. Atmospheric concentrations were determined from the corresponding species in the condensate. Several trace gases have been detected by the condensate method. Concentrations of two of these, ammonia and nitric acid, are compared with filter methods, with reasonably good agreement. Comparison is also made with concentrations of ammonia, formaldehyde, nitric acid and nitrous acid found by others under similar conditions. Typical daily variations of trace components in more remote areas surrounding Tucson, Arizona, are presented in an attempt to estimate background Southwest U.S.A. levels; these are as follows: 1.0 ppb for ammonia, 0.5 ppb for formaldehyde, 0.1 ppb for nitrous acid, 0.4 ppb for nitric acid, 1.1 ppb for formic acid, 0.9 ppb for acetic acid, 0.3 ppb for sulfur dioxide, 0.3 ppb for hydrochloric acid and 1 ppb for hydrogen peroxide. The diurnal variation of these gases and relationship between them is discussed. Possible sources of error in the condensate method of sampling are considered. The collection rate of water vapor is measured and compared to that theoretically predicted; explanations are presented for the discrepancy between the two. The sensitivity to errors in the measurement of the collection temperature and dew point temperature is determined.

Cloud reflectivity is a function of cloud liquid water content and droplet number concentration. Since cloud droplets form around pre-existing aerosol particles, cloud droplet number concentration depends on the availability of particles that can serve as cloud condensation nuclei. Given constant liquid water amount, increased availability of cloud condensation nuclei leads to clouds with a greater droplet number concentration, greater total droplet surface area and consequently, greater reflectivity. The change in cloud reflectivity resulting from the increased availability of condensation nuclei is known as the aerosol indirect effect. The aerosol indirect effect ranks as one of the largest sources of uncertainty in current estimates of global climate change, largely due to difficulties in measurement. Changes in cloud reflectivity resulting from the aerosol indirect effect are typically much smaller than the natural background variability observed in clouds. As a result, the modification signal is very difficult to detect against the background noise. Additionally, since atmospheric aerosols are ubiquitous, it is difficult to find polluted and nonpolluted clouds that are sufficiently alike for reasonable comparison. However, ship tracks seen in satellite images present one opportunity to study the aerosol indirect effect in relative isolation. Ship tracks are regions of enhanced reflectivity in marine stratus, resulting from the addition of aerosols from ship exhaust plumes to preexisting clouds. Ship tracks are a common feature of satellite images of the North Pacific. Since the marine atmosphere has comparatively low background aerosol concentrations, the addition of ship exhaust particles can lead to distinct increases in cloud reflectivity. Ship tracks allow for sampling of polluted and nonpolluted clouds from adjacent regions with similar solar and viewing geometry, cloud temperatures and surface properties, and consequently provide a unique opportunity to study the effects of aerosol modification of cloud reflectivity. Using satellite images of the North Pacific in July 1999, over 1000 ship tracks were identified, logged and analyzed, yielding 504 sets of radiance data matching polluted clouds with nearby nonpolluted clouds. It was expected that increasing the size of the region for selection of nonpolluted clouds would increase the variability in observed reflectivity, and make detection of the modification signal more difficult. In order to study this potential effect of domain size for selection of nonpolluted clouds on measurements of the aerosol indirect effect, three data sets were collected, using domain sizes for selection of nonpolluted clouds of 15, 50 and 100 km. Analysis of retrieved optical depth and droplet effective radius for modified and control pixels shows evidence of a 1-5% increase in visible optical depth of marine stratus following modification by addition of ship exhaust particles, but unexpectedly, shows only slight increases in uncertainty with increasing domain size. A subsequent study revealed that autocorrelation lengths of radiances and retrieved cloud properties were only 8-15 km. This indicates that even the 15 km control domain captured much of the background variability present. Domain sizes smaller than 15 km are difficult to sample automatically while avoiding the inclusion of polluted clouds in the nonpolluted cloud sample. As a result, it remains necessary to analyze large numbers of ship tracks to separate the aerosol modification signal from the background variability. / Graduation date: 2003