The Valencia Anchor Station aims to develop validation studies of low-spatial resolution remote sensing data and products under the framework of the SCALES (SEVIRI and GERB Cal/Val Area for Large Scale field ExperimentS) Project. The methodology so far developed has been achieved by using CERES (Clouds and the Earth's Radiant Energy System) observations taken in PAPS (Programmable Azimuth Plane Scanning) mode over the Valencia Anchor Station reference area. The purpose of this work is to compare Top of the Atmosphere (TOA) radiances and fluxes measured by CERES to those simulated by STREAMER radiative transfer code fed with surface and atmospheric parameters specially gathered during the Second GERB Ground Validation Campaign at the Valencia Anchor Station in February 2004. In this work, we include the selection of atmospheric profiles from on-purpose radiosonde and GPS (Global Positioning System) data, a realistic BRDF (Bidirectional Reflectance Distribution Function) estimation for the large-scale area and STREAMER radiative transfer simulations of TOA shortwave and longwave radiances and fluxes under clear sky and cloudy sky conditions. For cloudy sky simulations, CERES-MODIS SSF (Single Scanner Footprint) data has been used to get the required cloud parameters (Wielicki et al,1996). The methodology here developed will be useful to validate the GERB (Geostationary Earth Radiation Budget) instrument on board METEOSAT-8).