The bulk of synoptic weather type research related to urban climate focuses on human health impacts; however, recent studies have begun to quantify urban heat island (UHI) magnitudes by weather type, or air mass classification. This study presents an analysis of UHI intensity through synoptic-scale air mass persistence during the spring season for four UHI-prone United States cities. Historical daily weather types for Birmingham, Alabama; Charlotte, North Carolina; Louisville, Kentucky; and St. Louis, Missouri were extracted from the Spatial Synoptic Classification database for 40 years from 1980 through 2019. Daily minimum surface air temperature data were downloaded from the Global Historical Climate Network to compute UHI. The historical daily weather type data were converted into a record of persistence, or the length of consecutive days that a synoptic weather type was in place at each location. A descriptive climatology of SSC weather types and UHI at each location was constructed before UHI magnitudes were segregated by day of persistence and examined for differences in intensity. Climatologically, the four urban areas experienced an increase in warm weather types at the expense of cool weather types throughout the study period. Specifically, the persistence of moist tropical weather types increased at a statistically significant rate at Birmingham, Charlotte, and Louisville, consistent with the theorized northward migration of the mid-latitude jet stream. Also evident is a statistically significant increase in UHI frequency and intensity at Birmingham, Charlotte, and Louisville during the study period. Results show that the moisture character of a weather type is an important differentiating factor in UHI intensification, as the mean UHI was found to increase with the persistence of dry weather types and decrease with the persistence of moist weather types, presumably reflecting differences in radiational heating and cooling with atmospheric moisture content. The most intense UHIs and the largest UHI magnitude increase by day of persistence are associated with dry weather types, which have become more frequent since 1980. The findings suggest that larger magnitude UHIs may become more common in the future should dry weather type persistence continue to increase. Higher urban temperatures put human health at risk due to a well-linked relationship between heat and mortality and morbidity rates. The effects of heat are cumulative; the more common persistent, oppressive days become, the larger the impact. / Master of Science / Most of the research related to variation in the warmth of an urban area relative to the surrounding rural area, or the urban heat island (UHI) effect, under varying air mass conditions (temperature and humidity) has focused on human health impacts. This study examines UHI intensity through regional-scale air mass persistence during the spring season in four UHI-prone United States cities. Historical daily air mass conditions in the form of weather types for Birmingham, Alabama; Charlotte, North Carolina; Louisville, Kentucky; and St. Louis, Missouri were downloaded from the Spatial Synoptic Classification database for the 40 years from 1980 to 2019. UHI values for each urban location were calculated using daily minimum air temperature data from the Global Historical Climate Network. A descriptive climatology of weather types and UHI magnitude at each of the four urban locations established long-term means and trends before analysis of UHI intensity through varying weather type residence times, or persistence. Time series analyses align with previous indications of an increasing persistence of weather types and an increase in the frequency of warm weather types at the expense of cool weather types during the spring season. An increase in both UHI frequency and intensity occurred through the study period at Birmingham, Charlotte, and Louisville. The mean intensity of the UHI was found to increase with the persistence of weather types of low humidity and to decrease with the persistence of moist weather types. The largest mean UHI and the largest UHI magnitude increase by day of persistence are associated with low humidity weather types, which have become more frequent since 1980. The impacts of heat are cumulative; persistently elevated temperatures are detrimental to human health.

Since climate change increases and changes constantly, it contributes to higher average temperatures, ice melting and has a great impact on our ecosystem. This will then lead to a warmer climate, which means increased precipitation and milder winters. One of the reasons to climate change is urbanization, meaning people moving to the cities. To succeed in changing the climate, international cooperation and common goals are required. At the northern part of Brynäs, in the municipality of Gävle, work is currently in progress around the area where the factory of Läkerol was once standing. The area continues to be rebuilt and the outcome will eventually be called Godisfabriken. There, amongst other, a car park will be built for the newly built homes. The aim of this study is to compare metal roofs, grey concrete roofs and green roofs within the two aspects of stormwater management and temperature. Then analyse which alternative of these three roofs would be most advantageous for the car park of Godisfabriken.   The focused roofs are green, metal and concrete. A green roof is when it's completely or partly covered by a layer of vegetation and metal roofs are different sheet roofs with steel and aluminium-zinc. Grey roofs are made of concrete which works as both floor and ceiling. A building's roof affects which air temperature the surroundings has with its slope, vegetation and surrounding buildings. Another problem with urbanization and a warmer climate is stormwater management, which means rain and melted snow from roofs, parking areas and other hard surfaces.   The method includes a literature study and calculations. The literature study gave research on temperature for all roofs as well as stormwater management for green roofs. Calculations were made for stormwater management and temperature with its flow, absorption, reflectance and heat transfer.   The literature study and the calculations showed that green roofs have a high SRI value of 80 while the remaining roof is at around 40. The higher SRI, the lower surface temperatures on the material. This is proven in both methods when green roofs according to the literature study received a maximum surface temperature of 38 °C and 48 °C. According to the literature study green roofs can preserve more than 50 % of the rainwater. They also had a water flow rate of 1.97 l/s, which is less than half of what the metal roof got in the calculations. Since green roofs had both low air and surface temperatures, as well as longer drainage times and most absorbed water, green roofs are a more suitable choice than metal and grey concrete. / Eftersom klimatförändringarna förändras och konstant ökar bidrar det till en högre medeltemperatur, att isen smälter och att ekosystemet påverkas. Detta kommer då leda till ett varmare klimat vilket medför ökad nederbörd och mildare vintrar. En av orsakerna är urbanisering vilket betyder att människor flyttar till städer. För att lyckas förändra klimatet krävs internationellt samarbete och gemensamma mål.   Vid norra Brynäs i Gävle kommun pågår just nu arbete runt området där Läkerolfabriken en gång stod. Gamla Läkerolområdet kommer slutligen bli Godisfabriken. Där kommer det uppföras ett parkeringshus till det nybyggda bostäderna. Syftet med denna studie är att jämföra metalltak, gråa betongtak och gröna tak inom de två aspekterna dagvattenhantering och temperatur, därefter analysera vilket alternativ av dessa tre tak som skulle vara mest fördelaktigt för Godisfabrikens parkeringshus.   De fokuserade taken var grönt-, metall- och betong tak. Ett grönt tak är då taket är helt eller delvis täckt av ett lager vegetation. Metalltak är olika plåttak med stål och aluminium-zink, gråa tak syftar på betongbjälklag som fungerar både som golv och tak. En byggnads tak påverkar vilken lufttemperatur omgivningen har, även takets lutning samt växtlighet och byggnaderna runt om. Ett annat problem med urbanisering och varmare klimat är dagvattenhanteringen, vilket innebär regn- och smältvatten från bland annat tak, parkeringsytor och andra hårdgjorda ytor.   Metoden innefattar en litteraturstudie samt beräkningar. Litteraturstudien gav forskning om temperatur för samtliga tak samt dagvattenhantering för gröna tak. Beräkningar genomfördes för dagvattenhantering och temperatur med dess flöde, absorption, reflektans och värmeöverföring.   Litteraturstudien och beräkningarna visade att gröna tak har ett högt SRI (Solar Reflectance Index) värde på 80 medan resterande tak låg på runt 40. Ju högre SRI desto lägre yttemperaturer på materialet. Detta bevisas i båda metodvalen då gröna tak enligt litteraturstudie fick en maximal yttemperatur på 38 °C och 48 °C enligt beräkningarna. De hade även ett dagvattenflöde på 1,97 l/s, vilket är mindre än hälften av vad metalltaken på 4,93 l/s fick vid beräkningarna och kan enligt litteraturstudien bevara mer än 50 % av regnvattnet. Då gröna tak hade både låga luft- och yttemperaturer samt längre avrinningstid och mest absorberat vatten visar det att gröna tak är ett mer lämpligt val än metall- och gråa betongtak.

Indiana University-Purdue University Indianapolis (IUPUI) / Extreme Heat Events are the leading cause of weather-related mortalities in the continental United States. Recent publications have suggested that vulnerability to extreme heat is impacted by variations in environmental and socioeconomic conditions, even across small spatial units. This study evaluated the usefulness of socioeconomic variables and satellite-derived environmental measurements as predictors of heat-related vulnerability during the July 14-17, 1995 heat wave in Chicago, IL. Geospatial analysis and statistical processes were implemented to identify and rank characteristics of vulnerable populations. Results suggest population density, educational attainment, age, and financial indicators are among the best predictors of heat vulnerability. Proximity to and intensity of Urban Heat Islands also appears to influence neighborhood vulnerability levels. Identification and mapping of vulnerability variables can distinguish locations of increased vulnerability during extreme weather conditions. These vulnerability maps could be utilized by city officials to plan and implement aid programs to specific high risk neighborhoods before an extreme heat event, and resulting health implications, occur. Continued study and implementation of these variables could also assist in identifying vulnerable populations in other urban environments, improve utilization of location-specific heat warning systems and impact new building policies to decrease vulnerability variables across the country.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Architecture / Doctoral / Doctor of Philosophy

abstract / Architecture / Doctoral / Doctor of Philosophy

Cities are often warmer than their surroundings, and this can lead to more energy being used to cool buildings. This study looks at one city, London, and assesses the impact of the urban environment on the amount of energy used for air-conditioning. There are three main strands to the work. First, it was important to determine just how great the variation in air temperature is, and how this varies through time and through the urban space. Eighty measurement stations were established along radiating lines from the centre of London as far as rural areas. These measured the air temperature simultaneously at hourly intervals for over a year. Second, to support the main data acquisition, short-term tests within London looked at specific aspects of the urban environment that affect air temperature: the effects of vegetation in parks, and facade colour in streets. Third, the impact on energy use of the measured temperature variation was then determined by using simulation to model a standard building in different urban contexts. The mean heat island intensity was found to vary with distance from the centre of London, and with the local degree of urbanization at any given distance. The maximum intensity reached 8°C on occasion but was more usually 1-2°C in the daytime and 3-4°C at night. The proximity of areas of vegetation, such as parks, to a site was associated with cooler daytime temperatures. The annual cooling load for a standard building at the centre of London was found to be 25% more than at a rural site. However, at the most urban sites over-shadowing reduced the cooling load to 14% more than at a rural site. Heating load decreased towards the centre, but on balance total annual load (for heating and cooling) rose towards the centre to 8.5% more than rural use, and then reduced at the most overshadowed sites. The balance of the effect of urbanization on heating and cooling load depended on the level of internal gain in the building. This study makes a significant contribution to understanding the balance of the impact of urban environments on the energy used for cooling and heating buildings.

Urban heat island (UHI) is a region of increased air temperature in the canopy layer and boundary layer of the atmosphere above the town or industrial agglomeration in comparison with rural surroundings. The difference in temperature increases with the size of the city. This study describes the dependence of the intensity UHI Central European cities on their size and position of their weather station. It uses a multiple linear regression model. The dependent variable Y entering the model (data from 40 cities) are UHImean and UHImax. They are calculated as difference in air temperature between the urban and the relevant rural weather station. The average intensity of the urban heat island (UHImean) is the average value of the UHI of all available data in the analyzed period (hourly measurements of air temperature [řC] for the years 1994-2012). The data are only taken from night times records between 21:00 and 4:00 UTC and on days with the average total cloud cover at the city weather station less than 0,5. The maximum intensity of the urban heat island (UHImax) is the average maximum value of the UHI per night. The data are taken under the same conditions as in the case of UHImean. Independent variables X are the size of built-up area (X1) and the position of the weather station calculated using the...

O potencial aumento da atividade convectiva e da severidade das tempestades proporcionada pela ilha de calor urbana das grandes cidades, já apontado por diversos autores, é verificado através de testes com o modelo BRAMS, em que o esquema TEB é ativado e desativado para dois casos de tempestade. Em seguida, cenários de crescimento da mancha urbana para o ano de 2030 e de aumento da área com construções altas foram utilizados para avaliar o possível aumento na quantidade de precipitação, nos índices de tempo severo e, consequentemente, na severidade das tempestades que podem ocorrer na região. Com os métodos de planejamento fatorial e separação de fatores, verificou-se que o aumento da mancha urbana é capaz de aumentar a quantidade de chuva sobre a RMSP, indicando que a mudança do uso do solo de rural para o urbano é determinante para este aumento. O aumento da área com construções altas possui uma tendência para causar supressão da chuva. O aumento da mancha urbana é o principal fator gerador de instabilidade e cisalhamento entre os ensaios. O fator de aumento da urbanização vertical causa diferentes impactos entre os dois casos de tempestade, um com aumento e outro com redução da instabilidade. Em ambos os casos a verticalização causa redução do cisalhamento. A interação entre os dois fatores, urbanização horizontal e vertical, gera um aumento da precipitação e um deslocamento maior da tempestade sobre a RMSP, em relação ao cenário atual, porém menor do que ocorreria para o cenário com apenas aumento da mancha urbana. / The potential increase in convective activity and severity, caused by urban heat island effect, is verified with tests using BRAMS model, between cases with and without TEB scheme for two storm cases. Scenarios of future urban area and increase of high buildings area was made to evaluate changes in rainfall, convective parameters, and consequently, in severe weather probability for the study region. Using factorial planning and factor separation methods, it was found that the urban area growth is capable to increase the amount of precipitation, mainly due to the land use change from rural to urban. In the scenario of building heights increasing, it was found a tendency for rainfall suppress. The urban area growth is the major factor contributing to increase atmospheric instability and wind shear. Vertical urban growth causes different impacts between two storm cases, one with an increase and other with a decrease in instability. In both cases there were reductions in wind shear. The interaction between two factors increases the amount of precipitation and the displacement of the storm over MASP, in relation to the current scenario, but less than would occur for the scenario with only urban area growth.

Com a crescente evolução da mancha urbana das cidades, o ser humano intensificou o seu uso sobre o espaço, ocasionando certas conseqüências socioambientais, intensificadas através de fenômenos climáticos, tais como: enchentes, a piora da qualidade do ar e do aumento da temperatura nas cidades, comparada a sua área entorno. Este último, também é conhecido como Ilha de calor. A área de estudo contemplada nesta pesquisa se justificativa pelo fato de apresentar: a) um crescimento acelerado da população urbana a partir de meados da década de 1970; b) um Intenso processo de verticalização iniciado na década de 1980 e c) por conseguinte a expansão da malha urbana da cidade, que convive com uma arborização muito reduzida. A partir destes argumentos, o presente trabalho procurou investigar a hipótese da constituição de um clima urbano associado ao crescimento da cidade sede do município de Viçosa. Para isto, primeiramente, analisou-se a série histórica da estação climatológica de Viçosa entre 1968 e 2006. E, em seguida, utilizou-se da técnica de transetos móveis, com a utilização de um termohigrômetro digital de leitura direta (MINIPA-MT-241), envolvido em tubo PVC recoberto por papel alumínio e colocado do lado de fora do carro há uma altura de aproximadamente 2,0m de altura. Este procedimento foi realizado em três escalas de análise: campocidade, área urbana e o centro da cidade e estações sazonais distintas. Depois de realizados os experimentos e analisado os registros históricos de temperatura do ar, pode-se dizer que Viçosa ainda não constitui um clima urbano, muito embora, possa ter sido possível identificar ilhas de calor na cidade, principalmente à noite. / With the increasing development of urban stain of cities, the human being intensified its use on the area, causing certain social consequences, intensified by climatic phenomena, such as flooding, the worsening air quality and increasing the temperature in cities compared to its surrounding area. The latter is also known as heat island. The study area included in this search was justified because the present: a) an accelerated growth of urban population from the mid-1970s, b) a Intensy verticalisation process started in the 1980s and c) therefore the expansion of urban network of the city, living with a very limited stock. From these arguments, this study sought to investigate the possibility of setting up a climate associated with the urban growth of the city headquarters of the municipality of Viçosa. For this, first analyzes the historical series of the climatological station of Viçosa between 1968 and 2006. And then it was used the technique of mobile transects, using a digital direct reading termohigrômetro (MINIPA-MT-241), involved in PVC pipe covered by aluminum foil and placed outside the car there is a height of approximately 2.0 m high. This procedure was performed on three scales of analysis: country-city, urban area and the city center and seasonal distinct seasons. After the experiments performed and analyzed the historical records of air temperature, we can say that Viçosa still not an urban environment, though, might have been possible to identify islands of heat in the city, mainly at night.