Near real time validation Hourly time scale For early detection of possible problems with satellite based retrievals of Surface Radiative Fluxes, timely comparison with ground observations is important. Capabilities were developed and implemented to use the six SURFRAD stations (Penn State, PA; Desert Rock, NA; Goodwin Creek, MS; Boulder, CO; Bondville, Il; Fort Peck, MT), to perform close to “real time” evaluation of satellite estimates against these observations. On the average, the SURFRAD data are available within three days from observation time. This time interval was selected for providing the evaluation results on this Web site. Comparisons on hourly time scale, representing the diurnal cycle at each location, will be kept on this WEB site for one month. Monthly scattergrams At the end of a one-month period, scatter-diagrams of hourly observation and relevant statistics for each station will be provided and kept on the Web site, for reference. Historic validation The objective is to provide results from ongoing evaluation activity, using observations from numerous available data sources, known to be of good quality. Due to the large amounts of data involved, and the different distribution time schedules of such data, only “historic” presentation of results is possible. Independent evaluation