Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 133-142). Also available in print.

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

Thesis (Ph.D.)--University of Delaware, 2005. / Principal faculty advisor: Frederick Nelson, Dept. of Geography. Includes bibliographical references.

A lot of research has been conducted in the past decades on urban heat island (UHI) all over the world. Nevertheless, the UHI effect has not been included in weather data used by building services engineers to design buildings and size their heating and cooling plants. This research was carried out to investigate the UHI effect in Greater Manchester by setting up fixed point monitoring stations over the city. Woodford Met Office ground observation station was selected to be the rural reference point. A multiple regression model was developed to incorporate the heat island effect into the Manchester weather data for engineering usage.It was found that the urban heat island intensity (the difference between the rural and urban area temperatures) can be as high as 8°C in summer and 10°C in winter in Manchester. Clear and calm nocturnal temperature data was used (when maximum heat island occurs ) to find the relationship between the UHI intensity and sky view factor (SVF), distance away from the city centre, evapotranspiration fraction (EF), wind speed, cloud cover and rural reference temperature. Results indicate that all factors have a negative linear relationship with UHI intensity. All measured data were fed into a statistical software package to create general linear regression models. Validation showed that these models were capable of predicting average UHI effect to a good accuracy. The maximum heat island effect peaks are not so accurate. However, an analytical model was developed based on energy balance equations to predict the maximum heat island effect. Validation shows a good prediction for summer but not so good for winter. This is probably due to the lower average UHI intensity in winter than in summer.

The urban heat island (UHI) effect is a phenomenon that results in cities being warmer than the surrounding rural areas, due to a large amount of impervious surfaces. The purpose of this study is to evaluate the effectiveness of green roofs to mitigate the effects of solar energy on a building in the southern United States. In order to test the green roofs, temperatures were monitored inside and on top of unconditioned model buildings with green and with traditional roofs. Over the course of the study, the data collected showed that green roofs provided a significant benefit for the buildings by reducing daily high temperatures during summer and daily low temperatures during winter, while also reducing temperature fluctuation. The findings of this study suggest that a green roof will reduce indoor temperature and rooftop temperature, while providing several other benefits for city inhabitants such as reduced air temperature.

No description available.

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

In the summer of 2007, the number of people living in the world’s urban areas exceeded that of those living in the countryside. Such urbanisation tends to modify the climates of towns and cities as a result of a number of factors which together form the ‘urban heat island’ effect. In order to better design buildings and urban areas to cope with these effects, it is first necessary to understand the heat transfer mechanisms which are taking place. The aim of the current research has therefore been to provide convective heat transfer data appropriate for low-rise urban environments by investigating the effects of wind speed, direction and street geometry. The research has employed the naphthalene sublimation technique which has been extended in several fundamental areas including development of a novel approach to measure the rate of sublimation from wind tunnel models. This technique has permitted measurements to be made over an array of discrete locations, revealing the variation across building surfaces. The uncertainty in the convective heat transfer coefficients obtained was calculated to be approximately ±6%. Tests were conducted in the BRE wind tunnel with an atmospheric boundary layer simulation appropriate to inner city areas. Cube models were arranged so as to form long rows of flat-roofed buildings referred to as ‘street canyons’. A series of correlations have been derived from the experimental results from which the rate of convection occurring from each building surface may be obtained with respect to wind speed. The greatest rates of convective heat transfer have been shown to occur at the top of the windward wall and leading edge of the roof, the lowest rates from the leeward wall of a building. Convection was found to be reduced in narrow street canyons. In wider street canyons, the convective coefficients on the exposed windward and roof surfaces of buildings were higher, but the values on the leeward wall are lessened due to the distancing of the downstream windward vortex. The effect of wind direction was found to be relatively small and therefore it is proposed that the convective heat transfer relationships presented may be applied irrespective of wind direction.

Climate change has already increased the frequency, intensity, and duration of heat waves around the world. In the coming decades, this trend will continue and likely accelerate, exposing much of the world’s population to historically unprecedented conditions. In some regions, extreme temperatures (as indexed by the annual maximum temperature) are projected to increase at a faster rate than mean daily maximum temperatures. This dissertation shows that under a high emissions scenario, by 2060 – 2080 models project that the most extreme temperatures could warm by 1 – 2°C more than the warm season average in some regions. This amplified warming of the most extreme temperatures is most pronounced in the eastern U.S., Europe, eastern China, and parts of the Amazon rainforest, and may have substantial implications for heat risk in these regions. This dissertation explores the physical mechanisms driving the projected amplified warming of extremes in climate models and assesses the associated uncertainty. It shows that the amplification is linked to reductions in cloud cover, increased net surface shortwave radiation, and general surface drying as represented by declines in the evaporative fraction. In addition to rising temperatures, atmospheric humidity has been observed to increase in recent decades and models project this trend to continue. As a result, joint heat-humidity metrics indicating heat stress are likely to rapidly increase in the future. This dissertation explores how extreme wet bulb temperatures may change throughout the century and assesses the risk of exceeding a fundamental human heat tolerance limit that has been proposed in prior research. It then combines climate data with spatially explicit population projections to estimate the future population exposure to unprecedented wet bulb temperatures. Several regions stand out as being at particular risk: India, the coastal Middle East, and parts of West Africa are likely to experience extremely high wet bulb temperatures in the future, and rapidly growing populations in these regions will result in large increases in exposure to dangerous heat stress. In some areas, it is possible that wet bulb temperatures could occasionally exceed the proposed human tolerance limit by 2080 under a high emissions scenario, but limiting emissions to a moderate trajectory eliminates this risk. Nevertheless, even with emissions reductions, large portions of the world’s population are projected to experience unprecedented heat and humidity in the future. The projected changes in extreme temperatures will have a variety of impacts on infrastructure and other human systems. This dissertation explores how more frequent and severe hot conditions will impact aircraft takeoff performance by reducing air density and limiting the payload capacity of commercial aircraft. It uses performance models constructed for a variety of aircraft types and projected temperatures to assess the payload reductions that may be required in the future. These payload limits, along with sea level rise, changes in storm patterns, increased atmospheric turbulence, and other effects of climate change, stand to have significant economic and operational impacts on the aviation industry. Finally, this dissertation discusses evidence-based adaptation strategies to reduce the impacts of extreme heat in urban areas. It reviews a body of literature showing that effective strategies exist to both lower urban temperatures on a large scale and drastically reduce heat-related mortality during heat waves. Many adaptation techniques are not costly, but have yet to be widely implemented. Given the rapid increases in climate impacts that are projected in the coming decades, it will be essential to rigorously assess the cost-effectiveness of adaptation techniques and implement the most efficient strategies in both high- and low-income areas.

Summary The development of urbanization and industrialization has improved the comfort level and the quality of human’s life effectively. But at the same time, it also caused many global environment problems, such as air pollution, greenhouse effect and urban heat island (UHI).  The environment cannot keep the balance because of lots of industrial activities, anthropogenic heat and building surface effect. Almost 3 billion people, who are living in cities, have to face this situation, and the quantity is still increasing. The authors use literature research methodology, case study, comparative study and trend analysis study while writing. UHI have a harmful effect (such like photochemical smog and increasing energy use) on urban ecological environment, daily life and health. As the product of urbanization and industrialization, UHI has become one of the most important climate issues. Urban green space is helpful to reduce urban heat islands. London has a better urban green space system to face UHI and Hong Kong still has a long way to improve the green environment for reduce UHI. This article consider that roof greening is a suitable method to help Hong Kong gets rid of urban heat islands. And the lighting and population could indicate the level of urbanization, also can reflect the effect of urban heat islands preliminary. Over-capitalized lighting will exacerbate urban heat islands.