Tillförlitlig global vegetationsinformation fran satellitdata-optimism eller realitet?

The continuous operation of the NOAA series of meteorological satellites from the early 1980s onward, and the use of time series of data from its AVHRR sensor have been instrumental in the development of a new paradigm in the area of global earth observation. The coarse spatial and high temporal resolution of the data contrasts sharply with the data characteristics of traditional earth resource satellites, such as Landsat and SPOT, with their high spatial and low temporal resolution. Numerous scientists have demonstrated the potential of the data for capturing seasonal variations in terrestrial vegetation. The enthusiam of researchers has led them to use time series of ANHRR data for almost every conceivable type of study, from mapping of deserts and forests to the monitoring of ecological conditions for locust infestations and the spread of malaria by mosquitoes, AVHRR data are not being used operationally in programmes issuing early warnings for drought and famine in semi-arid areas. However, studies of the quality of the data cast some doubts over previous optimism. How do we come to terms with the contradictory results and what are the implications for the future use of the data?.