MODIS/TERRA MOD13Q1 Vegetation Indices 16-Day L3 Global 250m

Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared reflectance, centered at 469-nanometers, 645-nanometers, and 858-nanometers, respectively, are used to determine the MODIS daily vegetation indices. The MODIS Normalized Difference Vegetation Index (NDVI) complements NOAA's Advanced Very High Resolution Radiometer (AVHRR) NDVI products provide continuity for time series historical applications. MODIS also includes a new Enhanced Vegetation Index (EVI) that minimizes canopy background variations and maintains sensitivity over dense vegetation conditions. The EVI also uses the blue band to remove residual atmosphere contamination caused by smoke and sub-pixel thin cloud clouds. The MODIS NDVI and EVI products are computed from atmospherically corrected bi-directional surface reflectance that have been masked for water, clouds, heavy aerosols, and cloud shadows. https://lpdaac.usgs.gov/lpdaac/products/modis_products_table全球中分辨率成像光谱仪（MODIS）植被指数旨在实现植被状况的一致性时空对比。研究采用中心波长分别为469纳米、645纳米与858纳米的蓝光、红光及近红外反射率，计算生成MODIS每日植被指数。 MODIS归一化植被指数（NDVI）可与美国国家海洋和大气管理局（NOAA）甚高分辨率辐射计（AVHRR）的归一化植被指数产品形成配套，为历史时间序列相关应用提供连续性保障。MODIS还新增了增强型植被指数（EVI），该指数可最大限度抑制冠层背景干扰，且在高密度植被区域仍能保持检测灵敏度。 增强型植被指数（EVI）同时借助蓝光波段，消除由烟雾及亚像素薄云引发的残留大气污染。MODIS归一化植被指数与增强型植被指数产品，均基于经大气校正、且已掩膜剔除水体、云层、重度气溶胶及云阴影的双向地表反射率计算得到。https://lpdaac.usgs.gov/lpdaac/products/modis_products_table