70. Mu, X.; Huang, S.; Ren, H.; Yan, G.; Song, W.; Ruan, G. Validating GEOV1 Fractional Vegetation Cover Derived from Coarse-Resolution Remote Sensing Images Over Cropland. *IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens.* **2015**, *8*, 439–446. [CrossRef]

71. Fiducial Reference Measurement for Vegetation (FRM4Veg) Site. Available online: https://frm4veg.org/ (accessed on 27 January 2020).

72. Ground-Based Observations for Validation (GBOV) of Copernicus Global Land Products Site. Available online: https://land.copernicus.eu/global/gbov (accessed on 27 January 2020).

73. Loew, A.; Bennartz, R.; Fell, F.; Lattanzio, A.; Doutriaux-Boucher, M.; Schulz, J. A database of global reference sites to support validation of satellite surface albedo datasets (SAVS 1.0). *Earth Syst. Sci. Data* **2016**, *8*, 425–438. [CrossRef]

74. Fell, F.; Bennartz, R.; Loew, A. Validation of the EUMETSAT Geostationary Surface Albedo Climate Data Record -2- (ALBEDOVAL-2). Available online: https://www.eumetsat.int/website/home/Data/TechnicalDocuments/index.html (accessed on 4 November 2019).

<figure><img src="image_15.png" /></figure>

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).