Inter-calibrating CERES Fluxes Using GEO and MODIS as Transfer Radiometers

The NASA CERES EBAF product provides the scientific community observed TOA SW and LW fluxes for climate monitoring and climate model validation. EBAF product has successfully merged the Terra and Aqua record with the NOAA-20 record by utilizing flux and cloud climatology adjustment factors as well as radiometrically scaling the CERES instrument across the sensors. Currently, Aqua-CERES is used to inter-calibrate the NPP-CERES and NOAA20-CERES instrument observations. The Aqua satellite has started drifting, thereby preventing any direct NOAA-20 and Aqua inter-calibration events over the tropics. Similarly, no direct coincident comparisons will exist between NPP and NOAA satellites, which will fly in the same 1:30 PM orbit but are positioned a half orbit apart. Transfer radiometers, such as geostationary imagers could facilitate future CERES sensor inter-calibration events.

The CERES project has a special scan mode to match GEO angular sampling in order to facilitate comparisons with the GERB broadband sensor on the Meteosat platforms as well as to validate GEO derived broadband fluxes. The GEO scan mode provides CERES fluxes at the exact same angular configuration as the GEO imager. Comparisons will be made with the Terra-CERES instrument in cross-track mode as well as in GEO scan mode, the observed GERB fluxes, and the GEO derived broadband fluxes. If this approach is successful, it can be used to radiometrically scale the future NOAA-22 Libra and NOAA-20 CERES observations.