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 provides 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 416 sparsely distributed networks worldwide and high-resolution long-term time series data corresponding to site-based data.  Furthermore, we thoroughly assessed the effectiveness of the dataset at sites with different degrees of spatial representativeness. The results demonstrate that using this dataset in validation outperforms the direct comparison between satellite and in situ site measurements over heterogeneous surfaces when in situ measurement footprints are less than satellite pixel size. The dataset offers a unique collection of coarse pixel scale relative ground "truth" with the widest spatial distribution and longest time series. By merging temporal information from ground-based observations and spatial information from high-resolution data, the dataset we provided represents a valuable resource for validating and correcting worldwide surface albedo products over heterogeneous surfaces.