Analysis of the Impacts of Regional Environmental Context on the Spatial Structure of Urban Heat Islands with Landscape Ecological Methods

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This study, based on the principles Landscape Ecology, uses ecological maps to express regional environmental contexts and climatic maps from satellite-sensed thermal images to express thermal characteristics of cities. It aims to clarity the impacts of urban ecological contexts on the formulation of urban heat islands through the comparative analyses of ecological and climatic maps.At the first, Landsat/TM images have been used for evaluating the heat island intensity of Tokyo Metropolitan Area. Zoning the study area from the center of Tokyo to west in 10km interval and regrouped land uses into major 8 categories, we found that the heat island intensity from Landsat/TM thermal images gives a good fitness with that from the ground air temperature observation. It implies that the satellite thermal images are applicable to evaluate the differences of local thermal environment between land uses and zones of cities.With the above knowledge, we applied an ASTER/TIR image for mapping and ana … More lyzing local thermal characteristics in Yokohama City. Based on raster thermal images and vector land use and buildings maps, four types of ecological cluster maps including high-densely built-up clusters, green land clusters, bare land clusters and industrial land clusters were created as ecological maps. On the other hand, using the ASTER/TIR image, four types of climatic maps including hot spot clusters, cool spot clusters, hot feature clusters and cool feature clusters were created.The ecological analyses of the above maps show that the intensities of thermal islands within clusters are more or less related to their sizes measured by area. The intensities of heat island of cool features have the strongest logarithmic function with its geometric areas. Theses relationships also exist in bare land clusters, high-densely built-up clusters and so on.More importantly, it is found that the spatial extends of cool features were largely affected by regional topological contexts. The cool feature in hills or slopes may spread downward if it is large enough. This explained the ability of thermal images for capturing the advections in regional scales. All of these findings are valuable information of the local climatic conditions for considering heat island counter measurements. Less