The validation of the 5-year Terra-based monthly CERES radiative flux and cloud product

The newly released 5-year Terra-based climate focused Clouds and the Earth's Radiant Energy System (CERES) Surface Radiation Budget Average (SRBAVG) data product contains 1° gridded radiative surface and top of atmosphere (TOA) fluxes, cloud and aerosol properties. A key feature of this product is the combination of CERES fluxes with imager-derived broadband fluxes from 5 geostationary satellites at 3-hourly intervals to minimize diurnal sampling errors of the sun-synchronous orbit of Terra. The major breakthrough in this new release is the ability to eliminate geostationary calibration changes in the merged CERES and geostationary product. Rigorous validation of these geostationary derived broadband fluxes is necessary for these fluxes to be used in studying long-term climate changes.

The full suite of CERES SRBAVG geostationary derived broadband flux validation activities will be presented in this paper. These include: 1. Monthly mean flux errors caused by simulated calibration errors of 5% in both the visible and IR geostationary radiances have been shown to be less than 0.1% due to careful constrainment to the observed CERES fluxes. 2. CERES observations from Aqua have been used as an independent dataset to test the Terra/geostationary interpolated fluxes. This flux difference represents a measure of the total interpolation error due to contributions from the geostationary calibration, narrowband to broadband conversion and CERES/geostationary normalization algorithm. The Aqua/Terra monthly flux consistency is also tested as a measure of the effectiveness of the geostationary data assisted interpolation.. 3. CERES-derived surface fluxes have been compared against 36 ground site radiometer datasets. Ground site fluxes provide an independent source of calibrated broadband fluxes. 4. Additional studies have demonstrated that geostationary viewing artifacts have been eliminated in the first 10 Principal Component (EOF) analyses of the monthly TOA shortwave (SW) and longwave (LW) flux fields; geostationary derived cloud properties and fluxes are consistent with computed radiative transfer fluxes; and shortwave directional models derived from geostationary fluxes are consistent with CERES fluxes in solar zenith angle.

All of the validation activities conclude that there are no systematic biases in the geostationary derived fluxes and that the RMS errors are within climate quality standards.