The NASA/GEWEX Surface Radiation Budget: First Look at Next Generation Shortwave Data Product

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. Temporal resolutions are 3-hourly, 3-hourly-monthly, daily, and monthly. 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 and recomputing their entire data series, to be released as the HX product, at 10km resolution. The large increase in pixel number will allow SRB greater flexibility in its own spatial resolution, allowing a higher resolution gridded product (e.g. 0.5 degree), as well as the production of pixel-level fluxes. 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-Institut 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 algorithm (GSW) with new ISCCP data, the various other improved input data sets and the incorporation of many additional internal SRB model improvements. Improvements in the primary shortwave code, the GEWEX Shortwave (or 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 distinction of ice cloud vs. water cloud radiative transfer is included.

This GSW version will be released as part of the SRB 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.