Figure 1. Example browse image that includes the Vancouver, Canada region, acquired by Landsat-7, 22 September, 2002.
Introduction
The Committee on Earth Observation Satellites is an international group that coordinates civil space-borne observations of the Earth, and provides the space component of the Global Earth Observing System of Systems (GEOSS). The CEOS Virtual Constellations concept was implemented in an effort to engage and coordinate disparate Earth observing programs of CEOS member agencies and ultimately facilitate their contribution in supplying the space-based observations required to satisfy the requirements of the GEOSS. The CEOS initially established Study Teams for four prototype constellations that included precipitation, land surface imaging, ocean surface topography, and atmospheric composition. The basic mission of the Land Surface Imaging (LSI) Constellation [1] is to promote the efficient, effective, and comprehensive collection, distribution, and application of space-acquired image data of the global land surface, especially to meet societal needs of the global population, such as those addressed by the nine Group on Earth Observations (GEO) Societal Benefit Areas (SBAs) of agriculture, biodiversity, climate, disasters, ecosystems, energy, health, water, and weather. The LSI Constellation Portal is the result of an effort to address important goals within the LSI Constellation mission and provide resources to assist in planning for future space missions that might further contribute to meeting those goals.
Figure 2. CEOS LSI Constellation Portal web page for additional information about mid-resolution, optical satellites and sensors.
The CEOS LSI Constellation Portal for GEOSS was designed and built by the LSI Constellation Study Team in response to input from the community of users of mid-resolution optical remotely sensed land satellite data and with strong support and assistance from the CEOS Working Group on Information Systems and Services (WGISS). CEOS agencies participating in development of this Portal include Centre National d’Etudes Spatiales (CNES), ComisiÌ_n Nacional de Actividades Espaciales (CONAE), Instituto Nacional de Pesquisas Espaciais (INPE), Indian Space Research Organisation (ISRO), National Aeronautics and Space Administration (NASA), Japan Aerospace Exploration Agency (JAXA), Geo-Informatics and Space Technology Development Agency (GISTDA), and the U.S. Geological Survey (USGS). Currently, the website provides information about, and links to, mid-resolution optical data (e.g., Figure 1) that are being collected by the aforementioned agencies or have been collected by them over the past 35 years.
The LSI Portal serves as a single web location for information about current and previous mid-resolution optical satellite systems and data. Mid-resolution optical systems are those that acquire reflected and/or emitted electromagnetic radiation in the visible, short-wave infrared and thermal infrared (VNIR, SWIR, and TIR) wavelengths with spatial resolutions nominally between 10 meters and 100 meters. The Portal provides users with 1) basic information about the mid-resolution, optical LSI satellites and sensors (Figure 2), 2) information helpful for applications of the data, and 3) active links to data search and order tools for CEOS agencies that offer open user access to mid-resolution, optical satellite data (e.g., Figure 3).
Figure 3. National Institute for Space Research (INPE) web page linked from CEOS LSI Constellation Portal for access to CBERS-2 browse images and data. 
The Group on Earth Observations (GEO) has established a Forest Carbon Tracking Task to assist countries that desire to establish national systems for monitoring forest change and associated carbon reporting. The LSI Portal has recently added a link to the GEO Forest Carbon Tracking Portal, and an additional link to the U.S. Geological Survey’s Earth Explorer system, that includes a search, browse, and data retrieval system for remotely sensed and other digital data. The Earth Explorer system recently added capabilities for users to select from seven different Forest Carbon Tracking sites located in regions for which data are currently available at no cost. Users may select locations of interest within the regions and review browse images of available data. If the browse information (e.g., Figure 4) indicates acceptable data, the user may then download the data associated with the browse image.
Future Plans for LSI Portal
Future enhancements to the LSI portal include collaboration with CEOS Working Group on Information Systems and Services (WGISS) to add additional sensor data from other optical (e.g., MODIS) land imaging systems. Additional enhancements may include expansion of functionality of the data search options to go beyond directory and metadata about sensors and platforms to being able to initiate a granule-level search across multiple LSI member systems.
Figure 4. Example Forest Carbon Tracking Initiative image available through U.S. Geological Survey's EarthExplorer web site. Image details: Entity ID: P227R062_7X20010730, Acquisition Date: 2001/07/30.
The CEOS LSI Constellation for GEOSS Portal provides access for the community of users interested in mid-resolution optical land remotely sensed data and information. The CEOS LSI Portal will continue to evolve and add additional links to land remotely sensed data and information in the future.
Thomas Holm is current co-chair, Kevin Gallo is a current member, and Bryan Bailey is a former co-chair of the CEOS Land Surface Imaging Constellation Study Team.
Reference
[1] G.B. Bailey, M. Berger, H. Jeanjean, and K. Gallo. 2007. ÛÏThe CEOS constellation for land surface imagingÛ in Proc. Society of Photographic Instrumentation Engineers (SPIE), Sensors, Systems, and Next-Generation Satellites XI, 2007, vol. 6744, pp. 674425-1 – 674425-8.