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).

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.

可见光红外成像辐射仪（Visible Infrared Imaging Radiometer Suite, VIIRS）/极地轨道环境卫星系统1号（Joint Polar Satellite System 1, JPSS1）的三级16天合成双向反射分布函数（Bidirectional Reflectance Distribution Function, BRDF）/反照率——500米近实时（Near Real Time, NRT）产品，简称VNP43IA2N，可提供分辨率为500米的双向反射分布函数与反照率质量数据。VNP43IA2N产品采用16天合成的VIIRS观测数据（即当日及此前15天的观测数据）每日生成该16天合成产品。
VNP43算法采用罗斯厚/李稀疏互易（RossThick/Li-Sparse-Reciprocal, RTLSR）半经验核驱动双向反射分布函数模型，借助VNP43IA1N输出的三类核权重参数重构地表各向异性效应，将方向反射率校正至标准观测几何（对应产品VNP43IA4N），同时计算本地正午时刻的积分黑空反照率（Black-Sky Albedo, BSA）与白空反照率（White-Sky Albedo, WSA，对应产品VNP43IA3N）。研究人员可通过简单多项式结合该双向反射分布函数模型参数，计算任意太阳照射角度下的黑空反照率。同理，借助简单多项式，黑空反照率与白空反照率科学数据集（Science Dataset, SDS）图层可用于手动估算瞬时实际反照率（蓝天反照率）。
VNP43IA2N数据集共包含11个科学数据集（SDS）图层，具体包括：VIIRS影像I1、I2、I3波段的双向反射分布函数/反照率波段质量（反演信息）、16天合成周期内的有效观测天数，以及陆地水体类型分类标志、积雪双向反射分布函数反照率分类标志、本地正午时刻与卫星平台名称。