Instantaneous Consistency of Top-of-Atmosphere Radiative Fluxes from CERES on Terra and Aqua Satellites

The CERES and MODIS instruments aboard the Terra and Aqua satellite provide important information on atmosphere and cloud properties for monitoring the Earth's radiation budget. In this study, CERES Single Scanner Footprint (SSF) dataset, which combines measurements of both instruments, is used to estimate consistency of instantaneous shortwave and longwave top-of-atmosphere (TOA)radiative fluxes. Applying narrow-to-broadband regressions and appropiate angular models to MODIS measurements, we compare near-nadir MODIS-derived and oblique CERES TOA fluxes. The uncertainty introduced by narrow-to-broadband conversion is removed with random noise technique.

The overall consistency for all-sky ocean TOA fluxes is close to 6%(17 W/m2) and 2.5%(5.5 W/m2) for shortwave and longwave, respectively. All-sky fluxes over land are consistent within 5%(15 W/m2) for shortwave and 2%(6 W/m2) for longwave. The Aqua instruments shows better consistency for fluxes over snow/ice surfaces due to improvements in imager cloud identification algorithm.

Instantaneous errors for shortwave TOA flux are also obtained independently by using new data product, in which MODIS, MISR and CERES measurements are merged together. The results from both methods are largely in agreement.