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

The VIIRS/JPSS1 Level 3 16-Day BRDF/Albedo - 500m Near Real Time (NRT), short-name VNP43IA2N product provides BRDF and Albedo quality at 500 meter (m) resolution. The VNP43IA2N product is produced daily using 16-day VIIRS data (i.e., the current day and the previous 15 days to produce 16-day product).

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 VNP43IA2N data product provides a total of 11 SDS layers including: BRDF/Albedo band quality (inversion information) and days of valid observation within a 16-day period for VIIRS imagery bands I1, I2, and I3, as well as land water type class flag, snow BRDF albedo class flag, local solar noon, and the platform name.

VIIRS/JPSS1 第三级 16 天反照率/反照率产品（简称 VNP43IA2N），以 500 米分辨率的近实时（NRT）形式提供，每日利用 16 天的 VIIRS 数据（即当前日及前 15 天数据）生成。该产品采用 RossThick/Li-Sparse-Reciprocal（RTLSR）半经验核驱动反照率模型（BRDF），通过 VNP43IA1N 中的三个核权重重建地表各向异性效应，并纠正方向反射率至共同的观测几何（VNP43IA4N），同时计算局部正午太阳黑照反照率（BSA）及白照反照率（WSA）（VNP43IA3N）。研究者可以利用 BRDF 模型参数结合简单的多项式，获取任何太阳光照角度下的黑照反照率。同样，BSA 和 WSA 科学数据集（SDS）层也可以通过简单的多项式进行操作，以手动估算即时实际反照率（蓝照反照率）。关于该方法的详细说明可在算法理论基础文档（ATBD）中找到，文档链接为 https://www.umb.edu/editor_uploads/images/school_for_the_environment_cs…。VNP43IA2N 数据产品包含 11 个 SDS 层，包括 BRDF/Albedo 波段质量（反演信息）和 16 天周期内 VIIRS 图像波段 I1、I2、I3 的有效观测天数，以及陆地水类型类别标志、雪 BRDF 反照率类别标志、当地正午太阳时、平台名称等。