abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--UCLA, 2008. / Vita. Description based on print version record. Includes bibliographical references (leaves 322-345).

Thesis--Universität Bonn.

This research focusses on observing and modelling the suburban surface energy balance. The initial objective is to use measurements to elucidate the controls on the size and temporal variability of the latent heat flux. This is achieved by synchronous observations of suburban and rural energy balances. On the basis of this comparison it is proposed that the day-to-day variability of the partitioning of the suburban turbulent fluxes is linked both to larger-scale atmospheric influences and variations in the energy and moisture availability within the suburban 'canopy'. This hypothesis is examined through measurement and modelling. Further observations of the suburban energy balance components reveal that the size of the Bowen ratio is linked to the surface moisture availability. This is comprised of soil moisture variations in unirrigated greenspace areas and also the anthropogenic influence of lawn irrigation. However, in addition to this, the day-to-day variability of the Bowen ratio is a function of an advective influence upon the saturation deficit in the surface and mixed-layers. The mechanisms which determine this relationship are identified as meso-scale advective effects resulting from differing land-uses. This influences the nature of the mixed-layer and hence surface fluxes. In light of this interaction of scales and atmospheric processes, a model is developed that couples advectively-dominated mixed-layer dynamics with surface-layer exchanges of heat and mass. The acronym for the model is SCABLE, Suburban Canopy and Boundary Layer Evaporation model). It predicts the diurnal evolution of the mixed-layer depth, temperature and humidity. The saturation deficit of the mixed-layer is an input to the surface evaporation model. In turn this enables the surface sensible heat flux to be calculated from the surface energy balance (using measurements of the available energy). This modelled surface sensible heat flux drives the growth of this mixed-layer and thus the rate of entrainment from the capping inversion. The temperature and moisture structure of the mixed-layer is determined by both inputs from the surface-layer, and from the "free" atmosphere. The suburban canopy evaporation sub-model is based on the 'big leaf' Combination model, with a parameterisation scheme for the surface and aerodynamic resistances based upon the approaches taken by Shuttleworth (1976, 1978). The model performs adequately for simulating the day-to-day variability of the saturation deficit and surface evaporation. Its performance on an hourly basis indicates that the model weaknesses lie in the simulation of the diurnal behaviour of the surface resistance and potential temperature of the mixed-layer. It is concluded in the thesis that such an approach is necessary and valid for predicting and understanding the evaporation regime in areas the size of suburbia. This is especially true where there is likely to be a combination of factors determining the surface evaporation rate. / Arts, Faculty of / Geography, Department of / Graduate

Urbanization and a changing climate have encouraged more discussion as to how the urban heat island affects humans and society. This research examines three temperature variables (air temperature, apparent temperature, and surface skin temperature) across the Jackson, Mississippi metropolitan area to determine if intra-city thermal variability in select neighborhoods and business districts is connected to the built environment of each location. Using hand-held observation equipment, official weather observations from nearby airports, and land cover data from the United States Geological Survey, this research suggests that the built environment is contributing to the thermal variability around the city; however, the fine scale variations require closer investigation of the built environment around them to confirm or deny their role in the variations. Some sustainable urban design recommendations such as street shading and increasing the tree canopy are included for select areas throughout the Jackson Metro (Lakeland Drive, the Governor’s Mansion, etc.).

Hui Shuk Ying. / Thesis submitted in: October 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 135-149). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.ii / ABSTRACT --- p.iii / 中文摘要 --- p.v / TABLE OF CONTENTS --- p.vi / LIST OF TABLES --- p.viii / LIST OF FIGURES --- p.ix / LIST OF SYMBOLS --- p.xii / Chapter CHAPTER I --- INTRODUCTION --- p.1 / Chapter 1.1. --- Background --- p.1 / Chapter 1.2. --- Situation in Hong Kong --- p.4 / Chapter 1.3. --- Physical setting of Hong Kong --- p.7 / Chapter 1.4. --- Climate of Hong Kong --- p.9 / Chapter 1.5. --- Objectives of the study --- p.12 / Chapter 1.6. --- Significance of the study --- p.12 / Chapter 1.7. --- Organization of the thesis --- p.13 / Chapter CHAPTER II --- LITERATURE REVIEW --- p.14 / Chapter 2.1. --- Introduction --- p.14 / Chapter 2.2. --- Nature of Urban Heat Island (UHI) --- p.15 / Chapter 2.3. --- Characterization of UHI --- p.16 / Chapter 2.3.1. --- Diurnal variation --- p.17 / Chapter 2.3.2. --- Seasonal variation --- p.19 / Chapter 2.3.3. --- Spatial distribution of UHI --- p.20 / Chapter 2.4. --- Effects of weather factors on UHI intensity --- p.22 / Chapter 2.5. --- Relationship between urban factors and UHI intensity --- p.27 / Chapter CHAPTER III --- WEATHER DATA AND METHODOLOGY --- p.34 / Chapter 3.1. --- Surface meteorological observation --- p.34 / Chapter 3.1.1. --- Meteorological stations --- p.35 / Chapter 3.1.2. --- Methods of observation --- p.40 / Chapter 3.2. --- Acquisition and processing of data --- p.42 / Chapter 3.3. --- Detection of urban heat island in Hong Kong --- p.46 / Chapter 3.4. --- "Characterization of UHI intensity, frequency and temporal patterns" --- p.48 / Chapter 3.5. --- Evaluation of relationship between UHI intensity and weather conditions --- p.49 / Chapter 3.6. --- Evaluation of correlation between UHI intensity and city growth --- p.51 / Chapter CHAPTER IV --- RESULTS AND DISCUSSION --- p.52 / Chapter 4.1. --- Temperature evolution in Hong Kong --- p.52 / Chapter 4.1.1. --- Urban center --- p.52 / Chapter 4.1.2. --- New town --- p.57 / Chapter 4.1.3. --- Rural areas --- p.64 / Chapter 4.1.4. --- Discussion of the temperature changes in Hong Kong --- p.68 / Chapter 4.2. --- Urban heat island in Hong Kong --- p.75 / Chapter 4.2.1. --- Basic characteristics of UHI --- p.75 / Chapter 4.2.2. --- Annual patterns of UHI --- p.83 / Chapter 4.2.3. --- Seasonal patterns of UHI --- p.87 / Chapter 4.2.4. --- Discussion of the UHI phenomenon --- p.96 / Chapter 4.3. --- Weather effect on UHI intensity --- p.102 / Chapter 4.3.1. --- UHI phenomena and weather conditions --- p.103 / Chapter 4.3.2. --- Relationship between UHI intensity and meteorological elements --- p.106 / Chapter 4.3.3. --- Discussion of weather effects on UHI intensity --- p.115 / Chapter 4.4. --- Correlation of urban indicators and UHI intensity --- p.121 / Chapter CHAPTER V --- CONCLUSIONS AND RECOMMENDATIONS --- p.128 / Chapter 5.1. --- Summary of findings --- p.128 / Chapter 5.2. --- Limitation of the research --- p.133 / Chapter 5.3. --- Prospects of the study --- p.134 / REFERENCES --- p.135

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

No description available.

abstract: Metropolitan Phoenix, Arizona, is one of the most rapidly urbanizing areas in the U.S., which has resulted in an urban heat island (UHI) of substantial size and intensity. Several detrimental biophysical and social impacts arising from the large UHI has posed, and continues to pose, a challenge to stakeholders actively engaging in discussion and policy formulation for a sustainable desert city. There is a need to mitigate some of its detrimental effects through sustainable methods, such as through the application of low-water, desert-adapted low-water use trees within residential yards (i.e. urban xeriscaping). This has the potential to sustainably reduce urban temperatures and outdoor thermal discomfort in Phoenix, but evaluating its effectiveness has not been widely researched in this city or elsewhere. Hence, this dissertation first evaluated peer-reviewed literature on UHI research within metropolitan Phoenix and discerned several major themes and factors that drove existing research trajectories. Subsequently, the nocturnal cooling influence of an urban green-space was examined through direct observations and simulations from a microscale climate model (ENVI-Met 3.1) with an improved vegetation parameterization scheme. A distinct park cool island (PCI) of 0.7-3.6 °C was documented from traverse and model data with larger magnitudes closer to the surface. A key factor in the spatial expansion of PCI was advection of cooler air towards adjacent urban surfaces, especially at 0-1 m heights. Modeled results also possessed varying but reasonable accuracy in simulating temperature data, although some systematic errors remained. Finally, ENVI-Met generated xeriscaping scenarios in two residential areas with different surface vegetation cover (mesic vs. xeric), and examined resulting impacts on near-surface temperatures and outdoor thermal comfort. Desert-adapted low-water use shade trees may have strong UHI mitigation potential in xeric residential areas, with greater cooling occurring at (i.) microscales (~2.5 °C) vs. local-scales (~1.1 °C), and during (ii.) nocturnal (0500 h) vs. daytime periods (1700 h) under high xeriscaping scenarios. Conversely, net warming from increased xeriscaping occurred over mesic residential neighborhoods over all spatial scales and temporal periods. These varying results therefore must be considered by stakeholders when considering residential xeriscaping as a UHI mitigation method. / Dissertation/Thesis / Ph.D. Geography 2011

Orientador: Archimedes Perez Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-09T02:41:52Z (GMT). No. of bitstreams: 1 Jardim_CarlosHenrique_D.pdf: 5974193 bytes, checksum: 5eab9064a5e6a62518e7e4825667f350 (MD5) Previous issue date: 2007 / Resumo: As modificações impostas pelas cidades ao comportamento dos elementos climáticos são insuficientes para a definição de um clima urbano. Mesmo num espaço relativamente pequeno, deve-se levar em consideração a influência de uma série de outros fenômenos climáticos, cuja gênese remonta a participação de fatores alheios à própria organização urbana. Com a finalidade de demonstrar isso, tendo como área de estudo a bacia hidrográfica do Rio Aricanduva na zona leste do município de São Paulo (SP), procurou-se avaliar a influência dos fatores geográficos de superfície no comportamento da temperatura e umidade relativa do ar em áreas urbanas, considerando como pressuposto a relação entre a sucessão dos tipos de tempo e as mudanças na configuração espacial desses elementos. Essas mudanças foram interpretadas, em seguida, como indicadoras do caráter ¿sistêmico¿ do clima. Os dados utilizados foram resgatados de trabalhos anteriores, além daqueles produzidos durante o desenvolvimento desta pesquisa entre 2004 e 2006. A análise envolveu o cruzamento dos dados mensurados com as características físicas do ambiente de coleta e do tipo de tempo no dia. Os resultados foram traduzidos numa série de cartas, com o propósito apresentar o fato geográfico-climatológico dentro da sua real dimensão de tempo e escala / Abstract: The modifications imposed by the cities to the behavior of the climatic elements are insufficient for the definition of an urban climate. Even in a space relatively small, it should be taken into account the influence of a series of other climatic phenomena, whose genesis raises the participation of factors strange to the own urban organization. With the purpose of demonstrating that, tends as study area Rio Aricanduva's basin in the area east of the municipal district of São Paulo (SP), it tried to evaluate the influence of the geographical factors of surface in the behavior of the temperature and relative humidity of the air in urban areas, considering as presupposition the relationship between the succession of the atmospheric states and the changes in the space configuration of those elements. Those changes were interpreted, soon afterwards, as indicative of the "systemic" character of the climate. The used data were rescued of previous works, besides those produced during the development of this research between 2004 and 2006. The analysis involved the crossing of the data measured with the physical characteristics of the collection atmosphere and of the meteorological conditions of the day. The results were translated in a series of maps, with the purpose to present the geographical-climatological fact inside of her real space dimension and time / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutor em Ciências