Global Maps of Urban Extent From Satellite Data

Although cities cover less than 1 percent of the world’s surface, urban areas are the nexus of human activity with more than 50 percent of the population and 70 percent to 90 percent of economic activity. As such, material/energy consumption, air pollution, and expanding impervious surface are all concentrated in urban areas, with important environmental implications at local, regional and potentially global scales.

New ways to measure the built environment over large areas are thus critical to answering a wide range of research questions on the role of urbanization in climate, biogeochemistry and hydrological cycles. In this ongoing research initiative, we have developed a new dataset depicting global urban land circa 2001-2002 based on moderate resolution imaging spectroradiometer (MODIS) 500-meter satellite data. Our methods exploit temporal and spectral information in one year of MODIS observations, classified using an ensemble decision tree classification approach.

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The new map of MODIS 500m Global Urban Extent is available free for download in a variety of formats and projections. To access the data:

1. Send an email to aschneider4@wisc.edu. Please include:
   • A description of how you will use the data, and
   • Your contact information
2. You will receive an email in response with the link to the data and the password for data access. Click on the links, and enter the password information.
3. Download the files and the readme information. Note that the size of the zipped data are 12-100 mb, but upon unzipping are roughly 3.5 gigabytes.

If you use the data in your own research, we ask that you cite the following publications:

Schneider, A., Friedl, M., Potere, D., 2009, A new map of global urban extent from MODIS data. Environmental Research Letters, vol. 4, article 044003.

Schneider, A., et al., 2010, Monitoring urban areas globally using MODIS 500m data: New methods and datasets based on urban ecoregions. Remote Sensing of Environment, in review.

For more information on the maps, please contact Annemarie Schneider at aschneider4@wisc.edu.