AHVRR (Advanced Very High Resolution Radiometer) Composites

Normalized Difference Vegetation Index (NDVI) Composites are produced from multiple Advanced Very High Resolution Radiometer (AVHRR) daily observations that have been composited together to create a nearly cloud-free image showing maximum greenness. An NDVI ratio is produced from bands one and two of the AVHRR composite to produce a derived NDVI band composite. Normalized Difference Vegetation Index (NDVI) Composites are produced from multiple Advanced Very High Resolution Radiometer (AVHRR) daily observations that have been composited together to create a nearly cloud-free image showing maximum greenness. An NDVI ratio is produced from bands one and two of the AVHRR composite to produce a derived NDVI band composite. The following NDVI products are available: Conterminous U.S. and Alaska Weekly and biweekly NDVI composites date from January 1989 to present. U.S. composites are cast to the Lambert Azimuthal Equal-Area projection. Alaska composites are cast to the Albers Equal-Area Conic projection. Distribution of the NDVI composites depends on the age of the image: 7- and 14-day (current) NDVI composites are weekly and biweekly updates produced within the last four weeks. The data includes a composite for each of the acquired AVHRR bands, as well as a derived NDVI band. 7- and 14-day (recent) NDVI composites are weekly and biweekly updates produced from the end of the previous year until four weeks prior to present. The data includes a composite for each of the acquired AVHRR bands, as well as a derived NDVI band. 14-day (historical) NDVI composites consist of biweekly composites produced from January 1989 to the end of the previous year. The data includes a composite for each of the acquired AVHRR bands, as well as a derived NDVI band. Satellite zenith, solar zenith, relative azimuth, and acquisition dates are also provided.