Evaluation of Urbanization Influences on Urban Climate with Remote Sensing and Climate Observations

Remote sensing data were utilized to assess urban land cover and its thermal characteristics through mapping sub-pixel impervious surfaces and assessing thermal infrared images. Landsat imagery was used to calculate variation in urban imperviousness from 1995 to 2002 in the Tampa Bay watershed, Florida. The urban-rural boundary and urban development density were defined by selecting certain imperviousness threshold values. Landsat thermal bands were processed to obtain radiant surface temperatures (Tb) to investigate the urban heat island (UHI) effect associated with increasing impervious surfaces both spatially and temporally. Analysis shows significant differences in Tb values associated with different percentages of imperviousness. Surface heat characteristics exhibit a close relationship with impervious surface intensities. An inverse relationship between imperviousness and Normalized Difference Vegetation Index (NDVI) was determined for several urban areas. Impacts of urbanization on the climate conditions of urban and suburban areas in the Tampa Bay watershed have been investigated by analyzing the change of Tb, imperviousness, NDVI using data collected from Landsat and historical climate information in the region. Local climate change was studied using multi-decade temperature and other climate observation information. Our results suggest that increasing urban imperviousness has a certain effect on the monthly average minimum surface temperature and seasonally averaged temperature changes in the watershed area. The information on the spatial and temporal distribution of imperviousness that objectively identifies and quantified urban land use intensity and change patterns also outlines UHI effect in the watershed.