The sprawling urban areas of today's world are becoming interconnected earth features through their environmental influences on the intervening undeveloped land. The effect of regional development on the local microclimate, i.e. the physical sensation of the immediate environment, can be perceived as a societal issue of direct concern to urban, suburban and rural dwellers alike. Since regional land cover changes brought about by human activity tend to occur incrementally, communities often do not realize the extent of their development and therefore the changes in their environment. It is difficult, however, to estimate the magnitude and spatial extent of specific changes from standard weather stations which have been organized in relatively sparse networks and particularly sited so as to avoid local influences. Multi-spectral satellite data thus provide the most efficient means of studying regional land cover patterns and local climates and possess considerable potential for urban analysis, especially if used in conjunction with related data and research methods.
Through a combination of satellite remote sensing and surface climate modeling, this work presents evidence of the impacts of human development on the surrounding microclimate for a rapidly urbanizing county outside Philadelphia, Pennsylvania, between 1987 and 1996. Changes in the biophysical parameters of surface temperature, fractional vegetation cover, percent impermeable surface, evaporative energy loss and surface moisture availability are resolved down to a scale of 1 km2. On average, land parcels undergoing urbanization are shown to display significant decreases in vegetation and surface moisture and increases in impermeable cover and surface temperature. Using multiple linear regressions, equations are formulated which predict the possible effects of various development plans on the local surface temperature and moisture. Initial land cover, as well as the original surroundings of the land parcel, are shown to play the primary roles in determining the microclimatic response of the region to a given land use change. Throughout this work, the information which is derivable from multi-spectral satellites is demonstrated to be capable of providing a frequent assessment of urban development from both a conventional land cover perspective and a more comprehensive environmental viewpoint. The use of satellite data can thereby enable urban planners and the community in general to make informed decisions from an extensive foundation.