2001-2022 vegetation phenology dataset from MODIS NDVI

For extracting vegetation phenology, we used the Normalized Difference Vegetation Index (NDVI) from the Terra MODIS MOD13C1 Version 6 product , which provides 16-day composite vegetation data at a 0.05° spatial resolution. The temporal coverage spans from 2001 to 2022. A Savitzky–Golay (S-G) filter was used to smooth noise and capture the overall seasonal curve. Then, an asymmetric Gaussian (A-G) function was used to fit the smoothed NDVI to get more accurately model phenological transitions. Spring and autumn phenological parameters (SOS and EOS)—were extracted using a dynamic threshold method (threshold = 0.5).

为提取植被物候信息，本研究采用Terra MODIS MOD13C1第6版产品中的归一化差分植被指数（Normalized Difference Vegetation Index，NDVI），该数据集提供空间分辨率为0.05°的16天合成植被数据。其时间覆盖范围为2001年至2022年。我们使用萨维茨基-戈莱（Savitzky–Golay，S-G）滤波器对原始数据进行平滑去噪，以还原整体季节变化曲线。随后，采用非对称高斯（Asymmetric Gaussian，A-G）函数对平滑后的NDVI数据进行拟合，以更精准地构建物候转换模型。最终通过动态阈值法（阈值设定为0.5）提取春季与秋季物候参数——返青期（Start of Season，SOS）与枯黄期（End of Season，EOS）。