Producing Long-Term Radiative Flux Data Sets From Satellite Analysis: Sample Results from the Next Version of the NASA/GEWEX Surface Radiation Budget Project

Given the importance of understanding the energy balance at the top-of-atmosphere and surface of the Earth, the NASA/GEWEX (Global Energy and Water Exchanges project) Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. The temporal resolution of the current data products are 3-hourly, 3-hourly-monthly, daily, and monthly and the spatial resolution is 1 degree. The current release 3.0 (available at gewex-srb.larc.nasa.gov) uses the International Satellite Cloud Climatology Project (ISCCP) DX product for pixel level radiance and cloud information. This product is subsampled to 30 km, resulting in pixel counts of ~10 per grid box. ISCCP is currently recalibrating, improving, and reprocessing their entire data series, to be released as the HX product, at 10km resolution. The large increase in pixel number will allow SRB greater pixel sampling for current 1 degree and provide for future flexibility in increasing to a higher resolution gridded product (e.g. 0.5 degree). Additionally, the SRB team is collaborating with other global GEWEX energy flux teams to improve key inputs such as the inclusion of an aerosol history, meteorological, and ozone data sets. For instance, the aerosol history will be specified from the first version of the Max-Planck-Institute Aerosol Climatology (MAC) containing a climatological coarse mode and an emission based fine mode history. Here we present our first look at results for the improved GEWEX Shortwave and Longwave algorithm (GSW and GLW) with new ISCCP data, the various other improved input data sets and the incorporation of many additional internal SRB model improvements. Improvements in GSW include the incorporation of variable composition aerosol from the MAC data set, an expansion of the number of wavelength bands is expanded from five to eighteen, and the inclusion of ice cloud vs. water cloud radiative transfer. The GLW improvements include the MAC aerosol vertical profiles, meteorology from HIRS, diurnally varying sea surface and land surface temperatures, and new topography, surface type, and snow/ice fields. These new products are compared against surface radiative fluxes measurements from the Baseline Surface Radiation Network (BSRN) and other global TOA and surface radiative data sets such as from the CERES Mission. Differences between CERES and SRB are used to help determine relative uncertainties of the radiation data products and are relevant to the quantification of uncertainties (i.e., bias and random errors) to the products that predate CERES. The latest SRB data products will be released as part of the Release 4.0 Integrated Product, recognizing the interdependence of the radiative fluxes with other GEWEX products providing estimates of the Earth's global water and energy cycle (I.e., ISCCP, SeaFlux, LandFlux, NVAP, etc.). The current schedule of this new data set is discussed.