NOAA Climate Data Record (CDR) of AVHRR Surface Reflectance, Version 4 (Version Superseded)

*Note: This dataset version has been superseded by a newer version. It is highly recommended that users access the current version. Users should only use this version for special cases, such as reproducing studies that used this version.* This dataset contains gridded daily surface reflectance and brightness temperatures derived from the Advanced Very High Resolution Radiometer (AVHRR) sensors onboard eight NOAA polar orbiting satellites: NOAA-7, -9, -11, -14, -16, -17, -18 and -19. Surface reflectance from AVHRR channels 1 and 2 (at 640 and 860 nm) are a NOAA Climate Data Record (CDR). The dataset spans from 1981 to 10 days before the present, and was processed from the AVHRR Global Area Coverage (GAC) Level 1b dataset. AVHRR GAC observations are packaged into data arrays with latitude and longitude dimensions of 3600 x 7200 covering the globe at 0.05 degree spatial resolution. This dataset is one of the Land Surface CDR products produced by the NASA Goddard Space Flight Center (GSFC) and the University of Maryland (UMD). Other Land Surface CDR products include the Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI) and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR). Improvements made for Version 4 include 1) additional data from NOAA satellites extending the time period, 2) improved geolocation accuracy from use of OLE instead of TLE, 3) center of the grid is used as the reference, and 4) data value of a grid cell is computed as an average of available good observations. The dataset is in the netCDF-4 file format following ACDD and CF Conventions. The dataset is accompanied by algorithm documentation, data flow diagram and source code for the NOAA CDR Program.