MODIS/Terra+Aqua BRDF/Albedo Model Parameters Daily L3 Global 500 m SIN Grid

The MODIS Near Real Time (NRT) MCD43A1N, MODIS Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters is produced daily using 16 days of Terra and Aqua MODIS data. This global gridded tiled product provides model parameters/coefficients (isotropic, volume and surface) for characterizing the BRDF of each pixel at 500m resolution in the sinusoidal map projection. BRDF at each pixel for the current day is derived by inverting all available good quality corrected surface reflectance observations acquired by Terra and Aqua MODIS from the 16-day period ending with the current data day. The daily observation are weighed as a function of quality, observation coverage and temporal distance from the current data date. Model parameters are stored as 3D datasets for each of the 7 land bands, visible, near-infrared and shortwave bands along with corresponding mandatory QA flags.
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 at MODIS Land Science Team website at https://modis-land.gsfc.nasa.gov/brdf.html

MODIS近实时（NRT）MCD43A1N数据集，即MODIS综合Aqua与Terra双向反射分布函数及反照率（BRDF/Albedo）模型参数，每日通过整合Terra和Aqua MODIS的16天数据生成。该全球网格化镶嵌产品提供了用于表征每个像素500米分辨率正弦地图投影下BRDF的模型参数/系数（各向同性、体积和表面系数）。当日每个像素的BRDF通过逆解16天内所获取的、以当前数据日结束的所有高质量的校正表面反照率观测数据而得。每日观测数据根据质量、观测覆盖范围以及与当前数据日期的时间距离进行加权。模型参数以3D数据集的形式存储，分别对应于7个陆地波段（可见光、近红外和短波波段）以及相应的质量评估（QA）标志。在集合61（C61）NRT BRDF/Albedo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/不连续性。C61算法的变更旨在最小化NRT与标准BRDF之间的差异。C61 NRT BRDF代码经过修改，允许在完全逆解全部输入后进行额外一轮幅度逆解。这一额外幅度逆解仅使用标准与NRT重叠的9天数据集，且赋予最后一天最高权重。更多详细信息请访问MODIS陆地科学团队网站：https://modis-land.gsfc.nasa.gov/brdf.html。