MODIS/Terra+Aqua Nadir BRDF-Adjusted Reflectance Daily L3 Global 500 m SIN Grid

The MODIS Near Real Time (NRT) Combined Aqua and Terra Nadir BRDF-Adjusted Reflectance, MCD43A4N, Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) dataset is produced daily using 16 days of Terra and Aqua MODIS data at 500 meter (m) resolution. This product in sinusoidal map projection that provides view angle corrected Nadir BRDF-Adjusted Reflectances (NBAR) at local solar noon for the 7 land bands, along with corresponding mandatory QA dataset.

There is a significant change in the science algorithm of the Collection 61 (C61) NRT BRDF/Albedo products and, therefore significant differences/discontinuities between the C6 and C61 products. C61 algorithm changes are intended to minimize the differences between the NRT and Standard BRDF. The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information from MODIS Land Science Team at:
https://modis-land.gsfc.nasa.gov/brdf.html

MODIS近实时（NRT）结合Aqua与Terra平台下方的双向反射分布函数（BRDF）校正反射率数据集MCD43A4N，每日生成，采用Terra和Aqua MODIS在500米（m）分辨率下，为期16天的数据。该产品采用正弦地图投影，提供当地时间正午视角校正的下方BRDF校正反射率（NBAR）数据，涵盖7个陆地波段，并附带相应的必选质量保证（QA）数据集。

在系列61（C61）NRT BRDF/反照率产品中，科学算法发生了显著变化，因此C6与C61产品之间存在显著差异/间断。C61算法的改动旨在最小化近实时（NRT）与标准BRDF之间的差异。C61 NRT BRDF代码经过修改，允许在完全反转后进行额外的量级反转，这一额外量级反转仅使用标准与NRT之间重叠的9天数据集，其中最后一天的数据权重最高。

更多相关信息，请参阅MODIS陆地科学团队网站：
https://modis-land.gsfc.nasa.gov/brdf.html