VIIRS/NPP BRDF/Albedo Model Parameters Daily L3 Global 500m SIN Grid NRT

The VIIRS/NPP BRDF/Albedo Model Parameters Daily L3 Global 500 m SIN Grid Near Real Time (NRT), short-name VNP43IA1N product provides BRDF/Albedo model parameters at 500 meter (m) resolution. The VNP43IA1N product is produced daily using 16-day VIIRS data (i.e., the current day and the previous 15 days).

The VNP43 algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VNP43IA1N to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VNP43IA4N), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VNP43IA3N). Researchers can use the BRDF model parameters with a simple polynomial, to obtain black-sky albedo at any solar illumination angle. Likewise, both the BSA and WSA Science Dataset (SDS) layers can be used with a simple polynomial, to manually estimate instantaneous actual albedo (blue-sky albedo). Additional details regarding the methodology are available in the Algorithm Theoretical Basis Document (ATBD) at https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs….

The VNP43IA1N data product provides a total of six SDS layers including: mandatory quality bands and three multi-dimensional model parameter bands representing fiso, fvol, and fgeo of the VIIRS imagery bands: I1, I2, and I3. Each data product file is provided in HDF-EOS5 format.

该VIIRS/NPP双向反射分布函数/反照率模型参数每日L3全球500米SIN网格近实时（NRT）数据产品，简称VNP43IA1N，提供500米分辨率的双向反射分布函数/反照率模型参数。VNP43IA1N产品每日生成，采用16天的VIIRS数据（即当前日及前15日）。VNP43算法采用罗斯厚/李稀疏-互反（RTLSR）半经验核驱动双向反射分布函数模型，利用VNP43IA1N中的三个核权重来重建地表各向异性效应，并将方向反射率校正至共同观测几何（VNP43IA4N），同时计算当地时间正午的集成黑天反照率（BSA）及白天反照率（WSA）（VNP43IA3N）。研究者可以利用双向反射分布函数模型参数，通过简单的多项式计算，获取任意太阳照明角度下的黑天反照率。同样，BSA和WSA科学数据集（SDS）层也可以通过简单的多项式计算，手动估算即时实际反照率（蓝天反照率）。有关方法论的详细信息可在算法理论基础文档（ATBD）中查阅，文档链接为https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。VNP43IA1N数据产品包含六个SDS层，包括强制质量带和三个多维模型参数带，分别代表VIIRS影像带I1、I2和I3的fiso、fvol和fgeo，每个数据产品文件以HDF-EOS5格式提供。