VIIRS/JPSS1 Nadir BRDF-Adjusted Reflectance Daily L3 Global 500 m SIN Grid NRT

The VIIRS/JPSS1 Nadir BRDF-Adjusted Reflectance Daily L3 Global 500 m SIN Grid Near Real Time (NRT), short-name VJ143IA4N product provides NBAR estimates at 500 meter (m) resolution. The VJ143IA4N product is produced daily using 16-day VIIRS data (i.e., the current day and the previous 15 days). The view angle effects are removed from the directional reflectances resulting in a stable and consistent Bidirectional Reflectance Distribution Function (BRDF) Adjusted Reflectance (NBAR) product.

The algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VJ143IA1N to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VJ143IA4N), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VJ143IA3N). 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 VJ143IA4N product includes six SDS layers for BRDF/Albedo mandatory quality and nadir reflectance for VIIRS imagery bands I1, I2, and I3.

VIIRS/JPSS1 Nadir 反射率方向性反射分布函数（BRDF）调整每日 L3 全球 500 米 SIN 网格近实时（NRT）产品，简称 VJ143IA4N，提供 500 米分辨率的全天对数反射率（NBAR）估计。VJ143IA4N 产品每日生成，基于 16 天的 VIIRS 数据（即当天及前 15 天的数据）。通过去除方向反射率中的视场角度效应，得到稳定且一致的双向反射分布函数（BRDF）调整反射率（NBAR）产品。

算法采用罗斯厚/李稀疏互易（RTLSR）半经验核驱动 BRDF 模型，利用来自 VJ143IA1N 的三个核权重，重建地表各向异性效应，校正方向反射率至统一的视场几何（VJ143IA4N），同时计算本地正午的黑天空反照率（BSA）和白天天空反照率（WSA）（VJ143IA3N）。研究者可以使用 BRDF 模型参数和简单的多项式，以获得任意太阳照射角度下的黑天空反照率。同样，BSA 和 WSA 科学数据集（SDS）层也可以通过简单的多项式使用，以手动估算瞬时实际反照率（蓝天空反照率）。关于方法的详细信息可在算法理论基础文件（ATBD）中找到，链接为 https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。

VJ143IA4N 产品包括六个 SDS 层，用于 BRDF/Albedo 必要质量和 VIIRS 图像波段 I1、I2 和 I3 的 nadir 反射率。