No description available.

Thesis (Ph.D.)--University of Rhode Island, 2009. / Includes bibliographical references (leaves 103-105).

Thesis (Ph. D.)--University of Chicago, 1963. / "ANL-6794." Includes bibliographical references (p. 164-168).

Thesis (Ph. D.)--University of Chicago, 1963. / "ANL-6794." Includes bibliographical references (p. 164-168).

Thesis (M.C.E.)--University of Delaware, 2008. / Principal faculty advisors: Jamie H. MacMahan and James T. Kirby, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

A thesis is presented which reports on an investigation into air quality with an emphasis on the design and development of a numerical model for the transport of gaseous and particulate pollutants in airborne and deposited matter. The reported programme of research was undertaken with the dual aim of; establishing a programme of monitoring in order that ambient concentrations of selected air pollutants, released from various sources proximate to the Dundee area, could be quantified and assessed; and implementing the design, development and verification of a computational prototype model for the simulation of short term air pollutant transport using available Personnal Computer (PC) technology. Four monitoring programmes were successfully undertaken and reported on during the course of research. Three of the monitoring programmes were concerned with the quantification and assessment of ambient concentrations of traffic related pollutants in and around urban areas within the City of Dundee, Scotland. The fourth monitoring programme reports on the quantification and assessment of the potential environmental impact of the Baldovie Municipal Waste Incinerator with regards to the stack emission of the heavy metals, Cadmium (Cd) and Lead (Pb). The findings of the reported studies were found to form original contributions to local knowledge as well as to the field of air quality. Some of the finding have been published in reputable journals (Collett <i>et al</i>, (1 9 9 7 )), (Collett <i>et al</i>, (1 9 9 8 )). Also presented is a detailed report on the design, development and verification of the Short term Atmospheric Pollutant Transport Analysis Model (SAPTAM). The SAPTAM model was developed to simulate short term pollutant dispersal accounting for the effects of atmospheric stability, terrain and secondary transport dynamics, such as, dry deposition, wet deposition and chemical reactions. The model employs a simplified three dimensional Eularian wind field generator (WIFS) coupled to a Lagrangian particle in cell model (PICATS). The PICATS model simulates pollutant dispersion by releasing pseudo particles into a resolved wind field and calculating the consecutive trajectory of each particle over time. The findings of the reported research programme clearly demonstrate that the SAPTAM model, while supporting a low computational overhead and high level of description, is capable of representing pollutant dispersion over a range of scales with an acceptable level of empirical adequacy. The reported work undertaken as part of the development and verification of the SAPTAM model collectively forms an original contribution to knowledge given that the derivation and implementation of the approach on a PC based platform is completely novel.

No description available.

The Southern Ocean is an important region for the sequestration of heat, carbon dioxide and other tracers. The Southern Ocean circulation is typically described in a circumpolarly averaged sense as a Meridional Overturning Circulation (MOC), but the detailed 3-D pathways that make up this circulation remain poorly understood. We use Lagrangian particle trajectories, obtained from eddy permitting numerical models, to map out and quantify different aspects of the 3-D circulation. We first introduce various definitions used to quantify efficient export from the Antarctic Circumpolar Current (ACC) to the subtropical gyres. Using these definitions, we show that the permanent northward export varies by water mass and occurs in localised regions; with 11 key pathways identified. We then examine the dynamics setting the location and efficiency of the identified pathways, which includes the investigation of the role of diapycnal mixing and the impact of short and long time variability in the flow. Although we show that the flow of particles in the 3-D model is predominantly isopycnal, we find that particles that are forced to remain on isopycnals lead to approx. 60% lower export (mainly via three pathways) than identical releases where the diapycnal component of advection is included. Enhanced upward mixing near rough topography, and downward mixing in the southeast Pacific, were shown to be mostly responsible for the export. In addition, we show that most of the export pathways are mainly influenced by timescales from 90 days to 20 years, which suggests that mesoscale eddies are not the leading-order importance in the northward export from the ACC to the subtropical gyres. However, we also find that mesoscale eddies and the mean-ACC flow play a significant role in setting the export from the ACC in some pathways. These results highlight the role of temporal variability and vertical transport in enhancing the northward flow from the ACC by allowing transport across barotropic streamlines and onto more efficiently exporting isopycnals. In addition, the asymmetrical response of the studied quantities emphasises the importance of the three dimensions in understanding the dynamics driving the overturning circulation. We also demonstrated that the annually repeating velocity fields, which are commonly used for trajectory calculations, increase the diapycnal transport of particles and as a consequence, increase the overall 20-year northward export from the ACC by approx. 10%. In the study of the meridional overturning circulation, we diagnose the geographical distribution of the streamwise averaged diffusivity calculated from meridional displacements of the Lagrangian particles. We examine streamwise averaging using both latitude and equivalent latitude and argue that the latter gives a more useful measure. Reconciling tracer and particle horizontal diffusivities, we show that in the ACC, the average diffusivity peaks between 1500m and 2500m with an average value of 1500 m$^{2}$/s and that it is highest near the topographic features. We compare the exact diffusivity and its approximation to show that an assumption of time homogeneity does not hold and therefore that standard expressions for diffusivity that assume time homogeneity are of limited usefulness. Finally, we use the calculated trajectories to provide a streamwise averaged 2-D advection-diffusion model of the Southern Ocean MOC and then examine the extent to which this 2-D model can capture the overall effect of the actual 3-D transport.

No description available.

published_or_final_version / Mathematics / Master / Master of Philosophy