JPSS VIIRS Surface Albedo

Team Members: Jingjing Peng and Zhen Song

What is Surface Albedo?

Surface Albedo (SURFALB) is the ratio of solar radiation reflected by Earth’s land/ice surface to the incoming solar radiation. It links the land/ice surface to the climate system and is widely used in energy-balance and radiation-budget studies.

Product Overview:

• EDR (granule, 750 m): The Enterprise VIIRS algorithm retrieves daily mean blue-sky albedo using a Direct Estimation Method from TOA reflectance. Separate LUTs are used for snow, bare soil, sea-ice, and generic land to improve accuracy across surface types.
• All-sky, gap-filled: Cloudy pixels are filled using temporal filtering of recent retrievals plus an albedo climatology, yielding gap-free daily coverage at L2; the product also includes sea-ice albedo.
• L3 global grid (1 km, sinusoidal): All L2 observations from the day are mapped to a fixed grid and composited. Selection prioritizes (1) clear-sky and favorable geometry (SZA/VZA < 60°), (2) retrieval path (snow > sea-ice > other), and (3) uses the median of the highest-priority group to reduce outliers. Quality flags indicate overall quality, cloud condition, and retrieval path.

Validation & Consistency

• Ground networks: Against well-maintained SURFRAD, ARM, BSRN, and NEON tower sites, VIIRS daily albedo shows very small bias and precision.
• S-NPP vs NOAA-20 vs NOAA-21: The three sensors agree well. Global mean differences are typically ≤ 0.005, with seasonal variations largely tied to snow/ice and viewing geometry.

Key Features

• Daily mean blue-sky albedo (not instantaneous).
• All-sky gap-filled L2 granules; global L3 gridded maps.
• Surface-type-aware LUTs (snow, bare soil, sea-ice, generic).
• Transparent quality flags (overall quality, cloud condition, retrieval path).

Reference:

1. Peng, J., Yu, P., Yu, Y., Jia, A., Wang, D., Wang, H., & Wang, Z. (2023). An evaluation of the NOAA global daily gap-filled VIIRS surface albedo. Remote Sensing of Environment, 298, 113822. [10.1016/j.rse.2023.113822]
2. Peng, J., Yu, Y., Yu, P., & Liang, S. (2018). The VIIRS sea-ice albedo product generation and preliminary validation. Remote Sensing, 10(11), 1826. [10.3390/rs10111826]
3. Wang, D., Liang, S., Zhou, Y., He, T., & Yu, Y. (2016). A new method for retrieving daily land surface albedo from VIIRS data. IEEE Transactions on Geoscience and Remote Sensing, 55(3), 1765-1775. [10.1109/tgrs.2016.2632624]