CIESIN Thematic Guides

NOAA/NASA Pathfinder AVHRR Land Data Set

The National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) are jointly involved in producing long-term time series Advanced Very High Resolution Radiometer (AVHRR) data sets, from the coarse-resolution Global Area Coverage (GAC) 4-km data stream from the NOAA AVHRR sensor. GAC data, routinely acquired daily on a global basis and archived on magnetic tape since mid-1981, will be transcribed to optical disk and calibrated to compensate for variations in sensor performance. The recalibrated GAC data will be used to develop three streams of data products, dating from 1982, intended for global studies of land, oceans, and atmosphere.

The NOAA/NASA Pathfinder AVHRR Land Data Set will be processed to a spatial resolution of 8 km and will include a computed Normalized Difference Vegetation Index (NDVI) greenness value on a daily global basis. Daily global data sets will be developed into 10-day maximum NDVI composited data sets to minimize cloud cover. The resultant composited data sets will provide a time series of uniform, nearly cloud-free, derived data sets providing highly repetitive, synoptic coverage of all global land areas. These data sets will be archived in the Earth Observing System Data and Information System at NASA's Goddard Space Flight Center. Further information on this data set can be found in the AVHRR Pathfinder Home Page.

The NOAA/NASA Pathfinder AVHRR Land Data Set is expected to be valuable for natural science studies involving long-term evaluations of ecophysical land surface properties at large regional, continental, and global scales. For human dimensions studies, the 8-km spatial resolution is too coarse to allow for much direct observation and evaluation of the results of human activities. The data could be useful, however, for helping to establish environmental context, such as typical seasonal progression and major episodic climatic events including droughts, floods, and major variations in the length of growing seasons.

The NOAA/NASA Pathfinder AVHRR Land Data set will provide the only consistent land-cover data on a global scale for the period of 1982 to present. Efforts to achieve globally extensive coverage with the full resolution 1.1-km AVHRR have been in effect only since 1992 as part of the International Geosphere-Biosphere Program Global 1-km Advanced Very High Resolution Radiometer Database.