CERES stands for Clouds and the Earth's Radiant Energy System. More information about CERES can be found at (http://terra.nasa.gov/Brochure/Sect_4-3.html) and (http://ceres.larc.nasa.gov/ceres_brochure.php).
The CERES instrument aboard many Earth-orbiting satellites records the flow of reflected Solar radiation and reprocessed longwave radiation in the Earth's radiation budget.