Global vegetation phenology from AVHRR and MODIS data

Seasonal climatic variability drives four successive phases of vegetation phenology: green-up, maturity, senescence and dormancy. These periods can be divided by four transition dates of phenological phases. An algorithm of maximal curvature detection is developed to measure these dates for vegetation communities at each vegetation cycle. This method is applied to detect vegetation phenology based on AVHRR and MODIS data from regional to global extents. The spatial distribution patterns of phenological phases and cycle modes are analyzed in association with such environmental factors as temperature variability, water availability and human activity.