Leaf phenology synchrony for Meso- and South America v2

The leaf phenology product presented here shows the amplitude of annual cycles observed in MODIS (Moderate Resolution Imaging Spectroradiometer) normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) 16-day time-series of 2000 to 2013 for Meso- and South America. The values given represent a conservative measure of the amplitude after the annual cycle was identified and tested for significance by means of the Lomb-Scargle Transform. The amplitude was derived for four sets of vegtation indices (VI) time-series based on the MODIS VI products (500m MOD13A1; 1000m MOD13A2). The amplitude value can be interpreted as the degree in which the life cycles of individual leaves of plants observed within a pixel are synchronised. In other words, given the local variation in environment and climate and the diversity of species leaf life cycle strategies, an image pixel will represent vegetation communities behaving between two extremes: * well synchronized, where the leaf bud burst and senescence of the individual plants within the pixel occurs near simultaneously, yielding a high amplitude value. Often this matches with an area of low species diversity (e.g. arable land) or with areas where the growth of all plants is controlled by the same driver (e.g. precipitation). * poorly synchronized, where the leaf bud burst and senescence of individual plants within a pixel occurs at different times of the year, yielding a low amplitude value. Often this matches with an area of high species diversity and/or where several drivers could be controlling growth. Full details about this dataset can be found at https://doi.org/10.5285/dae416b4-3762-45bd-ae14-c554883d482c本数据集提供的叶片物候产品，展示了2000年至2013年中美洲与南美洲区域，由中分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer，MODIS）获取的归一化差分植被指数（Normalized Difference Vegetation Index，NDVI）与增强型植被指数（Enhanced Vegetation Index，EVI）的16天时间序列的年循环振幅。 所给出的振幅值为经Lomb-Scargle变换（Lomb-Scargle Transform）识别并检验显著性后得到的振幅保守估算值。 本数据集基于中分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer，MODIS）的植被指数（Vegetation Index，VI）产品（500米分辨率MOD13A1、1000米分辨率MOD13A2），针对四组植被指数时间序列计算得到振幅值。 该振幅值可表征单个像元内观测到的植物叶片物候周期的同步程度。 换言之，考虑到局地环境与气候的差异以及物种叶片物候策略的多样性，单个影像像元所代表的植被群落会处于两个极端状态之间： * 高度同步：像元内所有植物的叶片展芽与衰老过程几乎同时发生，因此振幅值较高。这类区域通常对应物种多样性较低的区域（如耕地），或所有植物生长受同一环境因子调控的区域（如降水驱动区域）。 * 低度同步：像元内不同植物的叶片展芽与衰老过程在一年中不同时段发生，因此振幅值较低。这类区域通常对应物种多样性较高的区域，或植物生长受多种环境因子共同调控的区域。 本数据集的完整详情可访问：https://doi.org/10.5285/dae416b4-3762-45bd-ae14-c554883d482c