VIIRS/JPSS1 Nadir BRDF-Adjusted Reflectance Daily L3 Global 1 km SIN Grid NRT

The VIIRS/NPP Nadir BRDF-Adjusted Reflectance Daily L3 Global 1 km SIN Grid Near Real Time (NRT), short-name VJ143MA4N product provides NBAR estimates at 1 kilometer (km) resolution. The VJ143MA4N 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 algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VJ143MA1N to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VJ143MA4N), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VJ143MA3N). 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 VJ143MA4N 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.

VJ143MA4N产品，简称VIIRS/NPP Nadir BRDF-Adjusted Reflectance Daily L3 Global 1 km SIN Grid Near Real Time (NRT)，提供1千米分辨率下的NBAR（归一化差分反射率）估算。该产品每日生成，基于前16天的VIIRS数据（即当前日及前15日）。通过移除方向反射率中的视场角效应，VJ143MA4N产品得以呈现稳定且一致的NBAR值。算法采用RossThick/Li-Sparse-Reciprocal（RTLSR）半经验核驱动BRDF模型，利用来自VJ143MA1N的三个核权重，重建地表各向异性效应，并将方向反射率校正至公共视场几何（VJ143MA4N），同时计算局部正午时刻的集成黑天空反照率（BSA）及白天空反照率（WSA）（VJ143MA3N）。研究者可通过简单多项式与BRDF模型参数结合，获取任意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）层也可通过简单多项式，用于手动估算即时实际反照率（蓝天空反照率）。有关方法论的详细内容，可在算法理论基础文档（ATBD）中查阅，链接为https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。VJ143MA4N产品包含18个SDS层，用于BRDF/Albedo的强制质量控制和VIIRS九个中等波段M1-M5，M7-M8，以及M10-M11的视场反射率。