Urban Dynamics: Data and Images

Temporal Urban Mapping - Urban Areas

National View of Urban Growth

Land use and land cover changes can be immense, but difficult to grasp when they occur incrementally. Recently, the data from Earth resource monitoring satellites has dramatically illustrated the rates at which these human-induced changes are occurring. Although, we see our cities grow month by month and year by year, we escape realization of just how much they have grown over a longer period. In particular, modern urban settlements are characterized by the proliferation of buildings, asphalt, concrete, and suburban gardens along with the displacing of agriculture and forestland. We fail to see how this growth, region by region, amounts to a significant global process.

The extent of urban or built-up areas for 1975 and 1995. The 1995 data is derived from a dataset of city lights assembled by NOAA using 231 nighttime orbits of the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (Elvidge et al.,in press). The 1975 data is from Digital Chart of the World, a dataset derived by the Defense Mapping Agency from the Operational Navigation Chart (ONC) map series.