Center for Environmental Science Applications (CESA)

Finding solutions to sustainability challenges by linking ideas, people and resources

The original 100 Cities Project, also referred to as the Urban Environmental Monitoring (UEM) project, at Arizona State University (ASU) was initiated by ASTER Team Member Dr. Philip R. Christensen to collect and analyze daytime and nighttime ASTER imagery over 100 urban centers. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging instrument flying on Terra, a satellite launched in December 1999 as part of NASA's Earth Observing System.

The major results of the project to date include the development of knowledge-based and object-oriented land use/land cover (LULC) classification algorithms that are generally applicable to all urban centers; quantification of the structure of the Phoenix urban landscape using spatial metrics; and investigation of correlations between a high-resolution LULC classification derived from ASTER and coarse resolution biophysical measurements obtained from the MODIS sensor in urban areas. Collaborations with scientists in such diverse urban centers as Berlin, Germany; Chiang Mai, Thailand; and Delhi, India have provided access to resources such as ASTER and Landsat data for research projects and student training, and the project has provided data used by numerous researchers and students at ASU.
The 100 Cities Project has also sought to understand how urban remote sensing can best be utilized with both researchers and practitioners in developing urban models, planning, and policy formulation. We are growing our international network of researchers and practitioners with a goal to be a significant provider of urban remote sensing images, processes, and models and provide outreach and education.
The project is located in ASU’s Mars Space Flight Facility, a part of the School of Earth and Space Exploration

Key Accomplishments 

Land Cover/Land Use Classifications 

  • Development and application of a expert system incorporating Landsat Thematic Mapper data, vegetation indices, image variance texture, and ancillary datasets to classify land cover in the Phoenix metropolitan region for a 1985-1998 time series.
  • Detailed landscape metric analyses using a fragmentation metric for comparison between 55 urban centers with varying geographic and climatic settings including North America, South America, Europe, central and eastern Asia, and Australia.

  • Developed two object-based classification schemes with ASTER data:  1) rapid and automated generic classifications with a small number of classes and little user input; 2) detailed classifications (i.e. more specialized classes), requiring some user input and model manipulation.  Neither scheme relies on ancillary data, allowing most any world city to be accurately classified to some level of detail.  Only the information contained in a multi-spectral satellite image is used to generate these classifications. These generic land cover maps provide the basis for urban change analysis, meteorological modeling, ecosystem function/ conservation work, and comparative urban studies.

 Examples of the rapid generic classification for 8 cities.

Meso-Scale Meteorological Modeling

  • Modification of the MM5 model using land cover classifications derived from Landsat and ASTER data is being used to characterize the current climatic conditions associated with urban centers, and assess change resulting from continuing (and predicted) modification of urban landscapes. This represents a significant contribution to studies of the effects of urbanization on global climate change.

Example land cover classification in MM5 for the Phoenix metropolitan area. Left panel is the standard 25 category USGS scheme, right panel is modified MM5 input using land cover classification of Stefanov et al. (2001a). 

Urban Heat Island Modeling 

  • Urban heat island modeling of Phoenix, Arizona, Chicago, Illinois, and also London with the National Center of Excellence on SMART Innovations for Urban Climate and Energy project at ASU. Surface temperatures derived from the ASTER Level 2 Surface Temperature dataset are used in urban heat island models with researchers and used to create heat island maps for city officials who are attempting to control heat island effects.

  • Superspectral data acquired by the NASA MASTER airborne sensor used to investigate social-biogeophysical microclimate interactions in Phoenix, Arizona neighborhoods.

Urban heat island (surface temperature) map of London, UK, September 16, 2003 (left) and Phoenix, AZ, July 11, 2005 (right). 

Disseminating and Archiving Data

  • Maintaining a current database of ASTER imagery for the 100 cities in the project. Raw data products are currently available only to collaborating scientists

  • Vegetation, surface temperature, and land classification maps for all cities

  • UEM has partnered with the Decision Theater on ASU’s campus to visualize ASTER imagery in an immersive space. Our urban remote sensing images and the products of our research are instructing researchers and practitioners on the utility of ASTER and urban remote sensing and are being applied to urban decision making.