The Evolution of U.S. Moderate Resolution Optical Land Remote Sensing from AVHRR to VIIRS

Moderate resolution satellite data have become an integral part of land remote sensing, which provide observations to support global and climate change research and applications of societal benefit. Starting with the NOAA Advanced Very High Resolution Radiometer (AVHRR), daily data analysis in the time-domain provided important new insights in vegetation studies at the global scale. Combining the temporal characteristics of the AVHRR and extending the spectral characteristics of the Landsat-5 Thematic Mapper, the NASA Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) instruments launched a new era in land remote sensing. The Terra and Aqua MODIS instruments now provide science quality, moderate resolution data with spatial resolutions from 250 m to 1 km. The next generation U.S. moderate resolution sensor, the Visible/Infrared Imager/Radiometer Suite (VIIRS), is scheduled to fly on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), expected to launch in October 2011, and subsequently on successive NPOESS platforms. The VIIRS instrument will transition much of the capability of the experimental MODIS instruments into the operational domain, a critical step for the land remote sensing community. This chapter provides the background to the current state of moderate resolution land remote sensing, and a description of the VIIRS instrument and the associated Environmental Data Records for the land surface. The VIIRS sensor and product similarities and differences with MODIS are described. The challenges in meeting the future needs for moderate resolution land remote sensing are discussed.