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

The VIIRS/NPP Albedo Daily L3 Global 500 m SIN Grid Near Real Time (NRT), short-name VNP43IA3N product provides albedo values at 500 m resolution for the bi-hemispherical reflectance white-sky albedos (WSA) and directional hemispherical reflectance black-sky albedos (BSA) at local solar noon. The VNP43IA3N 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 VNP43IA3N product provides a total of 9 SDS layers including: BSA, WSA, and mandatory quality layers for VIIRS imagery bands I1, I2, and I3.

该VIIRS/NPP反照率每日L3全球500米SIN网格近实时（NRT）产品，简称VNP43IA3N，提供500米分辨率的半球反射白天空反照率（WSA）和局部太阳中午方向半球反射黑天空反照率（BSA）值。VNP43IA3N产品基于当前日及前15日的16天VIIRS数据进行每日生成。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（BRDF）模型，利用VNP43IA1N中的三个核权重，重建地表各向异性效应，将方向反射率校正至共同的视几何（VNP43IA4N），同时计算局部太阳中午的黑天空反照率（BSA）和白天空反照率（WSA）（VNP43IA3N）。研究人员可以使用BRDF模型参数与简单的多项式相结合，获取任何太阳光照角度下的黑天空反照率。同样，BSA和WSA科学数据集（SDS）层也可以与简单多项式结合，手动估算瞬时实际反照率（蓝天空反照率）。关于该方法论的更多详细信息，请参阅算法理论基础文档（ATBD），链接为https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。VNP43IA3N产品提供总共9个SDS层，包括：BSA、WSA以及VIIRS图像波段I1、I2和I3的强制质量层。