Global Clumping Index Product Derived from VIIRS BRDF Data (2012–2023)

Specifically, the NIR band was selected as the primary BRDF data source to minimize CI retrieval uncertainty. The dataset utilizes an updated RossThick-LiSparseReciprocal_Chen (RTLSR_C) model, which incorporates hotspot parameters (C1 and C2) specifically optimized for VIIRS to accurately reconstruct hotspot and dark spot reflectances. This approach effectively overcomes potential scale effects in hotspot signatures that often arise when using prior values from sensors with different pixel resolutions.

Furthermore, an enhanced lookup table was established as a backup algorithm to reprocess anomalous values and pixels under snow-covered conditions, ensuring the spatial completeness of the global record. Extensive validation against field measurements confirms the reliability of the dataset, with the main algorithm achieving a RMSE of 0.07 and a bias of -0.01. The backup algorithm also demonstrates robust performance with an RMSE of 0.09.

The product successfully captures the complex spatial patterns of vegetation structural hierarchy across diverse land cover types at both regional and global scales.