GLOBAL-SCALE ASSESSMENT OF VEGETATION PHENOLOGY USING NOAA AVHRR SATELLITE MEASUREMENTS/

Phenology and associated canopy development exert a strong control ove r seasonal energy and mass exchanges between the earth's surface and t he atmosphere. Satellite measurements are used to assess main phenolog ical stages of the vegetation at the global scale. The authors propose a method to derive the start, the maximum, the end, and the length of the vegetation cycle, based on the analysis of temporal series of wee kly vegetation index, at a resolution of 1 degrees lat x 1 degrees lon g for year 1986. Global maps of these characteristics of the vegetatio n are presented, and their zonal distribution is discussed. The start of the vegetation cycle has been related to temperature sums in the ca se of temperate deciduous forest and to precipitation in the case of s avannahs. It is concluded that satellite measurements offer interestin g perspectives for global-scale quantitative phenology modeling.