The multiscale LUM data structure used hierarchical layers to build a complete LUM (Fig. 2). For each LUM layer, albedo and BRDF statistics were generated for a given land cover class if there were enough samples. Table 2 lists the selected layers we generated and the minimum required numbers of pixels for generating the statistics over all IGBP classes. At the base resolution (0.05 deg CMG resolution), the minimum required numbers of pixels for an IGBP class was defined as 2 (of the total of 36 pixels in a 0.05 deg cell) so that more spatial detail could be reserved. At a coarser resolution, the required numbers of pixels were raised () so the statistics are more robust. The sample size of 20 allows finding an estimate of the population standard deviation within 30% of the true value with a confidence level of 95% for a normal population. In the work, we included spatial resolutions at 0.05, 0.075, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 7.5, 10, and 360 deg. The percentages of valid statistics for all IGBP classes (land surface) increase as the cell spatial resolution decreases. These percentages were computed based on the total numbers of global pixels including both water and ocean, thus the percentages (mostly land surface) are relatively low. For the coarsest global layer (360 deg, corresponding to a single, global LUT), statistics are available for every IGBP class under snow-free conditions, but some IGBP classes (e.g., evergreen broadleaf forest) still lack sufficient samples under snow-covered conditions.