Remote Sensing Glossary

Maximum NDVI Composited Data Set: A satellite image data product that provides near-concurrent coverage of large regions of the globe, such as continental land masses, with minimal cloud obscuration. The product is produced by selecting cloud-free values of the Normalized Difference Vegetation Index (NDVI) from successive daily acquisitions of Advanced Very High Resolution Radiometer (AVHRR) data and retaining the maximum value, which is assumed to be least contaminated by clouds, for each pixel location. The compositing period generally is limited to a 10-day or semi-monthly time interval to minimize temporal variations in the resultant data product. Generally, AVHRR data are composited for a succession of time periods throughout a growing season or a year to create a time series of cloud-free data sets for extensive regions.

Normalized Difference Vegetation Index (NDVI): A transformation of satellite image spectral data computed as the ratio of the red (R) and near infrared (NIR) spectral bands as follows: NDVI = (NIR-R)/(NIR+R). The resulting index value is sensitive to the presence of vegetation on the global land surface and reported uses of NDVI address issues of vegetation type, amount, and condition.