Validation of the CERES SYN1deg Edition-4 GEO enhanced TOA flux product

The Clouds and the Earth's Radiant Energy System (CERES) project currently provides the climate community with observed TOA flux products. CERES relies on geostationary imagers to derive hourly regional broadband fluxes to estimate the daily shortwave and longwave flux between CERES measurements. CERES has now incorporated 18 geostationary GEO imagers over the CERES record beginning in early 2000 over five contiguous GEO domains. The GEOs are all of varying degrees of imager quality, number of spectral channels, channel bandwidth and calibration drifts. All of these factors can cause GEO artifacts to appear in the CERES SYN1deg Ed4 TOA retrieved cloud properties. The GEO cloud properties are used to compute the surface fluxes in this product. The derived GEO TOA broadband fluxes are carefully normalized to the CERES fluxes to mitigate any imager induced discontinuities between sensors.

The SYN1deg Ed4A product is an improvement over the Ed3A product. The product improvements include, the GEO calibration, using multiple spectral channels to retrieve clouds rather than using a simple visible and IR channel cloud retrieval algorithm, the GEO temporal sampling resolution was increased from 3-hourly to hourly, the LW narrowband to broadband incorporates both the GEO water vapor and window channel, rather than relying on an assimilated humidity profile with the window channel. The success of the CERES narrowband to broadband technique is the normalization of the GEO fluxes to the CERES observed fluxes to mitigate regional GEO flux biases and artifacts. The presentation will highlight the improved GEO calibration, the GEO derived LW fluxes, and the regional diurnal SW fluxes. Also, the GEO normalization procedure is tested by artificially changing the GEO imager calibration and comparing the GEO derived fluxes for consistency.