Phenological monitoring of grassland and larch in the Alps from Terra and Aqua MODIS images

This study compares MODIS NDVI 16-day (250 m) time series, acquired by Terra and Aqua platforms, for monitoring the phenological cycle of larch and grasslands in an alpine environment. The accuracy of MODIS 250 m Terra and Aqua phenological metrics �as evaluated for larch forests through comparison �ith field data. At regional level it �as carried out a correlation analysis bet�een the mean dates of start and end of season detected from MODIS Terra and Aqua in different years. Regional maps of start and end of season �ere derived from MODIS data and the interannual phenological variability of both ecosystems �as evaluated. Annual anomalies of the beginning of the gro�ing season, obtained from satellite data, �ere related �ith air temperature anomalies, computed from meteorological stations, to evaluate the effects of recent climate variability on the vegetation phenological cycle. Comparison �ith field phenological observations sho�ed that the start and the end of phenological cycle can be accurately determined from MODIS Terra and Aqua data and that an increase/decrease of 1°C in spring temperature lead to about 10 days in advance/ delay of the start of the gro�ing season.