Orbital and cloud cover sampling analyses for multisatellite earth radiation budget experiments

Computer simulations have been performed to determine the geographical and temporal coverage of various satellite orbits and scanning and nonscanning radiometers for earth radiation budget measurements. These results were used to simulate the sampling of a diurnally varying cloud and radiation field for several different satellite systems to estimate errors in regional monthly mean reflected radiation. The combined results indicate that coincient observations with a minimum of one sun-synchronous satellite and a midinclined orbit satellite are needed to obtain the required regional, zonal, and global coverage with sufficient temporal sampling for obtaining accurate estimates of monthly mean reflected solar radiation. Overall, the best sampling capability and lowest errors were obtained with a three-satellite system, i.e., two sun-synchronous satellites with different equatorial crossing times combined with either a 46 or 57-deg orbit satellite. The results from these analyses have been used in defining a joint NASA-NOAA multisatellite mission for an earth radiation budget experiment.