Comparison of GERB instantaneous radiance and flux products with CERES Edition-2 data

Whenever possible, intercomparisons of Earth radiation budget data from different spaceborne instruments should be made as they are important steps in the overall validation process. Intercomparisons are also key elements to compile long-term climate datasets by merging data from several instruments. In this study the GERB Edition-1 and CERES Edition-2 data are compared for June and December 2004. The comparisons concern shortwave and longwave radiance and flux at the top-of-atmosphere. Three different GERB level-2 data products with differing space–time characteristics are compared with data from the 4 CERES instruments. In general, the GERB unfiltered radiances and fluxes are found to be 5.9% and 7.5% higher than CERES for the shortwave. The GERB longwave radiance and flux are 1.3% lower than CERES. Analysis separated by scene type reveals differences between the GERB products. These differences should be taken into account by the user of the GERB data. The LW flux intercomparison shows angular dependency problem affecting the GERB dataset in cloudy and aerosol regions.