A coarse pixel scale ground "truth" dataset based on the global in situ site measurements from 2000 to 2021.

In situ measurements from sparsely distributed networks worldwide are a valuable source of data for validating satellite products. However, the significant differences in spatial scale between in situ and satellite measurements pose a challenge for validation. To address this challenge, we propose a new global coarse pixel-scale ground "truth" dataset which provide sequential pixel scale albedo on a 500 m resolution over the period 2000-2021. The creation of data set is done using ground measurements from 368 sparsely distributed networks worldwide and high-resolution long-term time series data corresponding to site-based data. Furthermore, we carefully evaluate the effectiveness of the new dataset over sites with different degrees of spatial representativeness. The results demonstrate superior overall accuracy compared to in situ measurement, especially in regions with strong spatial heterogeneity while most in situ measurements have poor spatial representativeness and cannot represent the pixel scale. The dataset offers a unique collection of pixel-scale relative ground “truth” with the widest spatial distribution and longest time series. Its ability to capture both spatial and temporal variations of surface albedo at coarse spatial scales makes it an invaluable resource for validating and correcting global surface albedo products.