Abstract: This document discusses and summarises two separate topics regarding cloud observations to be collected at the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) sites: (i) recommendations for reporting the existing cloud observations at GRUAN sites (primarily to help identify “clear” scenes for satellite sensor validation), and (ii) initial recommendations for generating cloud-related GRUAN data products, keeping in mind the GCOS cloud-related Essential Climate Variables (ECVs).
