Local Area Coverage (LAC) data collected by the Canada Centre for Remote Sensing (CCRS) from the Advanced Very High Resolution Radiometer (AVHRR) instrument on board the National Oceanic and Atmospheric Administration (NOAA) 11 and 14 satellites were used in the AVHRR Geocoding and Compositing (GeoComp) system. This system operating at the Manitoba Remote Sensing Centre (MRSC) in Winnipeg, Manitoba generated Canada-wide 10-day composite images at 1-km spatial resolution. The composite images cover the growing season from April 11 to October 31 for 1993 to 1999 (20 composite maps per year or 140 in total). In GeoComp, the maximum value of the Normalized Difference Vegetation Index (NDVI) computed from the top-of-atmosphere (TOA) radiance data was used to composite images with reduced radiometric artifacts. The GeoComp 10-day composite data were then reprocessed using the Atmospheric, Bidirectional and cloud Contamination Corrections of CCRS version 2 (ABC3v2) software system at CCRS to apply a refined sensor calibration and other radiometric product improvements. The resulting data set are as free of residual errors as possible, from effects not representing the surface under uniform illumination and viewing conditions. Consequentialy, they approximate nadir-viewed composite images obtained under cloud-free conditions during the growing season.
The resulting 1-km resolution composite maps include: a contaminated pixel mask; the smoothed surface reflectance in AVHRR bands 1, 2 and 3 corrected for bidirectional reflectance function (BRDF); the smoothed Normalized Difference Vegetation Index (NDVI) computed from surface reflectance; the relative azimuth angle; the relative date; the satellite zenith angle; the sun zenith angle; and the smoothed surface temperature corrected for emissivity effects. The data layers and the underlying data processing are described in detail in the data set description document ABC3v2.txt (ASCII text) or ABC3v2.doc (MS Word document) available from CCRS. The data layers, originally generated in Lambert Conic Conformal projection have been reprojected into geographic (latitude/longitude) coordinate system. Both projections use the NAD83 datum.
