Land Surface Albedo and BRDF

Team Members: Jingjing Peng, Zhen Song, and Peng Yu

Daily and Hourly Albedo/BRDF Parameters from VIIRS and GOES-R Observations

Purpose:

A set of advanced algorithms has been developed to retrieve surface Bidirectional Reflectance Distribution Function (BRDF), white-sky and blue-sky albedo, and nadir BRDF-adjusted reflectance (NBAR) products using observations from VIIRS (onboard JPSS satellites) and ABI (onboard GOES-R satellites). These algorithms provide comprehensive parameters that characterize the Earth’s surface reflectance properties and directional reflectance behavior.

What Problem Do They Solve?

Understanding land surface reflectance is essential for interpreting satellite observations and modeling energy and carbon fluxes. BRDF and albedo parameters quantify how different surfaces reflect solar radiation under various illumination and viewing geometries. This is crucial for correcting directional effects in remote sensing, improving radiative transfer modeling, and supporting vegetation, snow, and climate monitoring applications. The radiative forcing induced by albedo changes highlights the important role of land surface dynamics in modulating global warming. The availability of daily and hourly BRDF/albedo enables near-real-time monitoring and assimilation into forecasting models.

How It Works, including the Development Process:

The BRDF/albedo retrieval algorithms use multi-angle or diurnal observations to estimate spectral and broadband surface reflectance anisotropy and integrated albedo. Key algorithm features include:

• For VIIRS:
  • Daily Mean Blue-Sky Shortwave Albedo
  • Daily Snow-Free BRDF and Albedo Products: Includes daily BRDF, spectral and broadband white-sky albedo, and black-sky albedo and NBAR at local solar noon.
  • Uses directional sampling and anisotropy modeling for VIIRS viewing geometry.
• For GOES-R:
  • Hourly Blue-Sky Shortwave Albedo, Daily BRDF, and NBAR at Solar Noon
  • Uses dense ABI diurnal observations to characterize surface anisotropy and calculate
  • high-temporal albedo at real-time solar angles.

The retrieval system includes embedded quality flags, and it supports real-time and climatological product generation. These algorithms are integrated into operational NOAA product suites and being adapted for near-real-time (NRT) data streams.