SPATIAL AND TEMPORAL ACCURACY OF COARSE RESOLUTION PRODUCTS OF NOAA-AVHRR NDVI DATA

Coarse resolution products of maximum value composite NDVI data, deriv ed from the AVHRR on board the NOAA-7, -9 and -11 series of polar-orbi ting satellites, are becoming increasingly available. One such product is the ARTEMIS African decadal NDVI data set, available on CD-ROM for the years 1981 to 1991. These data have inherent spatial and temporal errors which arise as a result of the sampling procedures involved in their generation This paper describes the way in which the ARTEMIS ND VI data are produced. It then describes the spatial and temporal accur acy of the data, estimated for a study area in East Africa, in terms o f: 1. their spatial resolution, 2. pixel locational errors, 3. samplin g biases and systematic errors introduced during the production of the data, and 4. the presence of signal noise in multi-temporal profiles of the data. The paper concludes that these errors may prove a conside rable limitation to the usefulness of the data for distinguishing spec ific habitats on the ground over small study areas, and that in the fu rther development of applications for these coarse resolution data set s, these errors must be taken into consideration.