Vegetation phenology data based on GIMMS4g NDVI from 1982 to 2020

We used five phenological extraction methods, which include three threshold-based methods (i.e., Gaussian midpoint, spline midpoint, and TIMESAT-SG methods) and two change-rate-based methods (i.e., the HANTS maximum and polyfit maximum methods), following previous studies, to retrieve spring (start of growing season, SOS) and autumn (end of growing season, EOS) phenological events . Phenological extraction based on multiple methods consists of three steps: (1) smoothing and interpolating the NDVI date to obtain the smooth and continuous NDVI daily time series, (2) using the threshold value (0.2 and 0.5) or the maximum rate of change to extract the vegetation phenology from each single method, and (3) averaging the phenological results obtained by different extraction methods to reduce uncertainties associated with a single method (due to the different fitting methods, interpolation methods, and threshold settings of different extraction methods).