VIIRS/NPP Nadir BRDF-Adjusted Reflectance Daily L3 Global 1km SIN Grid NRT

The VIIRS/NPP Nadir BRDF-Adjusted Reflectance Daily L3 Global 1 km SIN Grid Near Real Time (NRT), short-name VNP43MA4N product provides NBAR estimates at 1 kilometer (km) resolution. The VNP43MA4N 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 NBAR product.

The VNP43 algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VNP43MA1N to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VNP43MA4N), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VNP43MA3N). 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 VNP43MA4N product includes 18 SDS layers for BRDF/Albedo mandatory quality and nadir reflectance for VIIRS nine moderate bands M1-M5, M7-M8, and M10-M11.

VIIRS/NPP 正射视场 BRDF 调整后的每日 L3 全球 1 公里 SIN 格网近实时（NRT）产品，简称 VNP43MA4N，提供 1 公里分辨率的 NBAR 估算值。VNP43MA4N 产品基于 16 天的 VIIRS 数据（即当前日及前 15 日）每日生成。通过移除方向反射率中的视场角效应，该产品实现了稳定且一致性的 NBAR，并计算了当地时间正午的集成黑天空反照率（BSA）以及白天空反照率（WSA）。VNP43 算法采用 RossThick/Li-Sparse-Reciprocal（RTLSR）半经验核驱动 BRDF 模型，利用来自 VNP43MA1N 的三个核权重重构表面各向异性效应，将方向反射率校正至公共视几何（VNP43MA4N），同时计算局部太阳中午的 BSA 和 WSA（VNP43MA3N）。研究人员可以使用 BRDF 模型参数与简单的多项式相结合，以获取任何太阳照明角度下的 BSA。同样，BSA 和 WSA 科学数据集（SDS）层也可以与简单多项式结合使用，以手动估算瞬时实际反照率（蓝天空反照率）。有关方法论的更多详细信息可在算法理论依据文档（ATBD）中找到，该文档位于 https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。VNP43MA4N 产品包括 18 个 SDS 层，用于 BRDF/Albedo 强制质量以及 VIIRS 九个中等波段 M1-M5、M7-M8 和 M10-M11 的正射反射率。