THE UNIVERSITY-OF-MARYLAND IMPROVED GLOBAL VEGETATION INDEX PRODUCT

Staff of the University of Maryland, Laboratory for Global Remote Sensing Studies have reprocessed the National Oceanic and Atmospheric Administration (NOAA) Global Vegetation Index (GVI) data record. Observations from April 1983 to June 1991 were mapped to a consistent projection (Plate Carree) and radiometrically calibrated to spectral reflectance. Sensor degradation with time was taken into account. The normalized difference vegetation index (NVDI) was computed and bi-weekly composites formed to reduce residual cloud contamination. In addition, a set of data quality indicators were compiled during processing. Inspection of the reprocessed observations indicates that they are a significant improvement over the original GVI data. The temporal patterns in the observations appear consistent over time and between sensor systems. Considerable local variance is still evident in the observations, particularly in humid, cloud-prone regions of the globe. This is indicative of inherent limitations in the GVI data files. The ancillary data files in the reprocessed record may assist in addressing this atmospheric contamination problem. These reprocessed measurements should be of value in current efforts to study biospheric dynamics and in the design of future remote sensing missions to study global change.