AVHRR Remote Sensing Phenology

The Remote Sensing Phenology (RSP) collection is a set of nine annual phenological metrics for the conterminous United States. Researchers at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center utilize data gathered by satellite sensors to track seasonal changes in vegetation. The two satellite sensors that provide the raw data for the RSP program are the Advanced Very High Resolution Radiometer (AVHRR) from National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites and the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard National Aeronautics and Space Administration (NASA) Terra and Aqua satellites. The satellite data are initially transformed into Normalized Difference Vegetation Index (NDVI) values. AVHRR NDVI and eMODIS NDVI provide the foundation for RSP. Time-series NDVI can be summarized and analyzed to produce nine key phenological indicators that represent a complete growing season. These data represent a powerful tool for documenting plant life-cycle trends over time and detecting the impacts of climate change on ecosystems. Remote Sensing Phenology Products Remote Sensing Phenology products are available in two file formats with geographic coordinates referenced to the Lambert Azimuthal Equal Area mapping grid: Georeferenced Tagged Image File Format (GeoTIFF) is a TIFF file with embedded geographic information. This is a standard image format for GIS applications. Band Sequential (BSQ) image file is a binary raster format with an accompanying header file which describes the layout and formatting of the file. EarthExplorer offers a year-to-year record of AVHRR Phenology data at 1-km resolution dating back to 1989 and eMODIS Phenology data at 250-m resolution dating back to 2001. Nine annual historical Remote Sensing Phenology metrics for the conterminous United States are available for each data set.