AUTHOR=Lyapustin Alexei , Wang Yujie , Korkin Sergey , Schaaf Crystal , Wang Weile , Wang Zhuosen TITLE=Scaled RTLS BRDF model extended to high zenith angles JOURNAL=Frontiers in Remote Sensing VOLUME=Volume 6 - 2025 YEAR=2025 URL=https://www.frontiersin.org/journals/remote-sensing/articles/10.3389/frsen.2025.1533803 DOI=10.3389/frsen.2025.1533803 ISSN=2673-6187 ABSTRACT=The Ross-Thick Li-Sparse (RTLS) model provides a good description of the surface bidirectional reflectance distribution function (BRDF) for zenith angles (ZA) up to ∼60°–70°. At higher zenith angles, the behaviour of the RTLS model is not well constrained. This becomes a limiting factor for the processing of geostationary satellite data covering the full range of solar and view zenith angles. Here, we propose a scaled sRTLS model extending the zenith angle range to ∼80°–84° and demonstrate an improved performance based on examples from the processing of GOES-16 ABI data using MAIAC algorithm.