MODIS/Terra Vegetation Indices 16-Day L3 Global 500m SIN Grid V061, 2021

The Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Indices 16-Day (MOD13A1) Version 6.1 product provides Vegetation Index (VI) values at a per pixel basis at 500 meter (m) spatial resolution. There are two primary vegetation layers. The first is the Normalized Difference Vegetation Index (NDVI), which is referred to as the continuity index to the existing National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) derived NDVI. The second vegetation layer is the Enhanced Vegetation Index (EVI), which has improved sensitivity over high biomass regions. The algorithm for this product chooses the best available pixel value from all the acquisitions from the 16 day period. The criteria used is low clouds, low view angle, and the highest NDVI/EVI value.
Provided along with the vegetation layers and two quality assurance (QA) layers are reflectance bands 1 (red), 2 (near-infrared), 3 (blue), and 7 (mid-infrared), as well as four observation layers.

搭载于Terra卫星的中等分辨率成像光谱辐射计（Moderate Resolution Imaging Spectroradiometer，简称MODIS）16天合成植被指数产品（MOD13A1）6.1版，以500米空间分辨率逐像素输出植被指数（Vegetation Index，简称VI）数值。该产品包含两类核心植被图层：其一为归一化差分植被指数（Normalized Difference Vegetation Index，简称NDVI），其被视作现有美国国家海洋和大气管理局-先进甚高分辨率辐射计（National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer，简称NOAA-AVHRR）所衍生NDVI的连续性指标；其二为增强型植被指数（Enhanced Vegetation Index，简称EVI），该指数在高生物量区域具备更优异的观测灵敏度。本产品的算法会从16天周期内的所有有效观测像素中选取最优值，选取标准为低云量、低观测视角以及最高的NDVI/EVI数值。除上述植被图层与两个质量保证（Quality Assurance，简称QA）图层外，该产品还附带反射率波段1（红光）、2（近红外）、3（蓝光）与7（中红外），以及四个观测图层。