naomi

North American Overlay Mapping

Layer Notes - Earth's City Lights

The background layer of Earth's City Lights is used with only two maps: Overview East and Overview West. This composite satellite photograph of North America clearly shows the actual light radiated from towns and cities all over the continent.

The image was created with data from the US Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth’s surface. The lights, derived from 9 months of observations by the Defense Meteorological Satellite Program, have been superimposed on a darkened land surface map.

The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of the continent would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. Even more than 100 years after the invention of the electric light, some regions remain thinly populated and dark. Deserts in the United States are poorly lit (except along the coast), as are the boreal forests of Canada.

A variety of different sized images covering the whole world can be downloaded from this website:
http://visibleearth.nasa.gov/cgi-bin/viewrecord?5826

Credits:
  • Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC.
  • Image by Craig Mayhew and Robert Simmon, NASA GSFC.
  • Satellite: DMSP
  • Data Source: DMSP OLS