About Cities From Space

The research presented here is primarily focused on the physical properties of a wide range of urban environments using passive measurement of optical reflectance and thermal emission as well as optical emission of nighttime lights. Comparative analyses of urban reflectance (visible and infrared color) and surface temperature allow us to develop robust criteria for distinguishing urban land cover from non-anthropogenic land covers. These analyses also provide important constraints on the physical properties that control mass and energy fluxes through the urban environment. These constraints are used as inputs to physical models of climatic, hydrologic and ecologic processes.

Characterizing the physical properties of urban land cover makes it possible to map the form and spatial extent of urban land use and to quantify changes in form and extent. This provides objective, physically-based metrics for comparative analyses of urban dynamics that cannot generally be obtained from administrative definitions of urban extent. Mapping provides static snapshots of the urban mosaic while monitoring allows us to quantify the spatiotemporal dynamics. Mapping urban extent with nightlights complements the information derived from optical reflectance.

Each city is linked to a jpeg image of a Landsat visible/IR composite collected by Landsat 5 (pre 1999) or Landsat 7. Most of the image areas are 30x30 km but a few are larger. All images are shown at full resolution (30 m pixel) so the scale (on screen) is equivalent. The jpeg compression causes significant loss of fine detail from the original image. Most of the images are about 200K (~40 seconds via 56K modem). A few are significantly larger.

The Interactive Map Viewer
http://sedac.ciesin.columbia.edu/ulandsat/

Interactive Map showing New Orleans scene- http://sedac.ciesin.columbia.edu/ulandsat/js_check/intMap.jsp

Using the interactive map viewer, users can easily select from an en extensive list of major cities around the World. Mouse over a city and a thumbnail will be displayed. Click the thumbnail to activate a control that will present a high-resolution image from the city of choice. For my test I selected New Orleans and was presented with a scene captured 9/17/2000. Right-clicking the scene enables me to download the image.

In some cases (eg. Miami, FL) an option to download the raw Landsat data is provided

To view the entire city collection simply jump to http://sedac.ciesin.columbia.edu/ulandsat/data.jsp

About CIESEN
The Center for International Earth Science Information Network (CIESIN) is a center within the Earth Institute at Columbia University. CIESIN works at the intersection of the social, natural, and information sciences, and specializes in on-line data and information management, spatial data integration and training, and interdisciplinary research related to human interactions in the environment.

See http://www.ciesin.columbia.edu/