We focus on the surface urban heat island (SUHI) and the spatiotemporal relationship between land use and surface temperatures (T s ) in Cuiabá-Várzea Grande, Mato Grosso, one of the major urban agglomerations of central-western Brazil, which has suffered intense urbanization processes since the 1960s. Supervised maximum likelihood classifications of optical bands of Landsat Thematic Mapper (Landsat TM) imagery from 1986 and 2007 are applied to generate land use/cover maps. Surface emissivity is determined using the logarithmic transformation of the normalized difference vegetation index. The T s is retrieved from the thermal bands utilizing a radiative transfer equation. In both cities, urban expansion followed two main development axes, which are reflected in the spatial patterns of T s . The highest values of T s were found in bare soil and urbanized areas. Between 1986 and 2007, T s increased 0.96 • C on average and a maximum of 5.49 • C in the urban agglomeration. The SUHI in Várzea Grande suffered intensification with an increase of 1.34 • C in the downtown area. This tendency was stronger in the center of Cuiabá, where T s increased 3.12 • C. Slowing this rapid rate of temperature increase would demand decisive intervention by municipal authorities, such as restricting annual occupation taxes, reducing the occupation coefficient in new districts, preserving native vegetation, and designating new green areas. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).Keywords: urban heat island; land surface temperature; land use and land cover change; urban development; Central Brazil.Paper 11079RR
Este estudo avalia a ilha de calor da superfície urbana e a relação espaço-temporal entre o uso da terra e a temperatura da superfície (Ts) na cidade de Várzea Grande, que juntamente com Cuiabá (capital do estado) formam um dos maiores conglomerados da região Centro-Oeste do Brasil, cujo processo de urbanização tem sido intenso desde a década de 60. Utilizou-se neste trabalho imagens multiespectrais do satélite LAN-DSAT-5 TM para elaborar mapas de uso e ocupação do solo e de temperaturas superfi ciais (Ts) e detectou--se a presença de ilha de calor urbana superfi cial (ICUS) na região central da cidade de Várzea Grande. Os resultados obtidos demonstram que os maiores valores médios de Ts foram encontrados em solos expostos (2,0°C) e em áreas construídas (2,13°C). No entanto, não se pode afi rmar que o ICUS seja um fenômeno consolidado na região. Com intuito de reduzir as Ts nas áreas urbanas da cidade, recomenda-se revisão nos índices urbanísticos e a promoção de ações que visem preservar a vegetação remanescente e implantar novas áreas verdes em posições estratégicas na cidade, bem como utilizar materiais alternativos que reduzam o armazenamento de energia.
In Brazil, studies to reuse construction and demolition waste are a special issue because a large amount of this material has been delivered to the public landfills and in illegal places. Some researchers have suggested reusing this material in building elements, such as bricks or blocks. It is possible to find a lot of researches in physical/ mechanical characterization, while little effort has been made to characterize recycled construction and demolition waste blocks (RCDW) for their thermal properties. The aim of this work was to characterize the RCDW thermal resistance and conductivity in order to provide subsidies for a building's thermal performance analysis. The hot-box method was adapted, together with measuring techniques with a heat-flow meter to determine the RCDW thermal properties. The results indicated that the RCDW block overall thermal resistance and thermal conductivity in the solid region was within the intervals of 0.33≤R T ≤0.41m 2 KW -1 and 0.60≤λ≤0.78Wm -1 K -1 , respectively. The lower resistance and conductivity values are justified by the presence of aggregate with a lower density and lower thermal conductivity than the natural aggregate.Thermal resistance and conductivity of recycled construction and demolition waste (RCDW) concrete blocks REM, Int. Eng.
Resumo Tem-se por objetivo analisar a influência da incorporação de areia de resíduos de construção civil (RCC) no comportamento físico e mecânico de misturas de solo-cimento autoadensável (SCAA), visando sua aplicação em sistema de vedação vertical monolítico. O método consiste em realização dos ensaios laboratoriais, considerando um traço inicial de cimento-solo na proporção 1:5, e mais quatro traços, em que se substitui o solo por areia de RCC em intervalos de 25% até 100%, em massa. No estado fresco, conduziram-se ensaios de espalhamento (faixa de 660 mm a 750 mm), densidade da massa e teor de ar incorporado e, no estado endurecido, ensaios de resistência à compressão simples, absorção de água e índice de vazios. Observou-se melhora na trabalhabilidade e na vazão mássica nas misturas híbridas, obtendo-se maiores resistências mecânicas nos traços com incorporação de 25% e 50% de areia de RCC, indicando um possível intervalo de dosagem ótima. Além disso, a incorporação de areia de RCC diminuiu a absorção de água, com valores abaixo de 20% em todos os traços híbridos. Conclui-se que a utilização de areia de RCC em misturas de SCAA apresenta potencial para aplicação de sistema de vedação vertical monolítico.
Seasonality and inter-annual variation of the energy balance of natural surfaces as the effect of conversion from natural to agricultural areas has been the object of much in-depth research in South America. However, none has assessed the effect of conversion from a native to an urbanized area. Current research was performed in the city of Cuiabá, in the Cerrado-Pantanal ecotone, state of Mato Grosso, central Brazil, featuring a tropical sub-humid climate (Aw). The paper investigates the pattern of energy fluxes exchanges in the rural and urban sites located in Brazilian savannah ecosystem. The heat stored inside the urban canopy (ΔQS) and within the rural area was obtained by the Objective Hysteresis Model (OHM) and by soil flux meter, respectively. Sensible (H) and latent (LE) heat fluxes were estimated by the Bowen Ratio Energy Balance (BREB). The rural and urban sites had different patterns in the micrometeorology variables Wind speed decreased and air temperature and vapor pressure deficit increased from rural to urban site. The urbanization also modified the energy fluxes partition of urban canopy by increasing ΔQs (12%) and H (60%) and by decreasing LE (29%), with β = 2.0 in contrast of rural canopy, where the partition was ΔQs (1.5%), H (29%), LE (64%) and β = 0.45. The ΔQS, H and LE were in phase with Rn, differing from what has been reported for sites in North America and Europe.
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