Shaping of neighborhood microclimates

The space and time domains of microclimates in cities are dominated by processes in single-family residential land uses due to the high percentages of these land areas in cities. In the parlance of urban climatology (Oke, 2006), microclimates are expressed at the local scale and in the urban-canopy zone near the earth’s surface. Ellefsen (1990/91) studied the morphology of cities and created estimates of percent area of single-family residential, residential apartment, industrial, and commercial zones. Many researchers have produced estimates of the green spaces and vegetative cover for cities (e.g., Nowak et al, 1996). Choices of landscaping, water systems, housing types, density patterns, architectural design of communities play a large part in the shaping and evolution of space-time microclimates. This is in addition to the unique environmental setting (latitude, elevation, rural land, and local terrain conditions) and dynamics of the regional climatic regime of heat and moisture. A major characteristic of microclimates in cities is the time-varying changes at the local level embedded in regional and global changes. The time-varying nature of microclimates is epitomized by several rates and kinds of change from slow to rapid, even jump-shift in nature, with increasing boundary densities among microclimate types. This presentation will give an example of Phoenix, Arizona’s microclimate distribution and changes over time from studies of sample neighborhoods and regional land use-scale evaluations to illustrate how the metropolitan area’s microclimates evolved in the past. The future resides in debates on preservation, adaptation and mitigation of urban ecological factors that would shape microclimates – thus, a shaping that has various levels of human influence and intentionality. The urban social and ecological ramifications of microclimatic conditions are vital to maintaining quality of life in cities.