The Incoming Longwave Radiation Data from UNL Data Set was collected as part of a study of thermal radiant energy from vegetative canopies. These data were collected during the growing season of 1987 and 1989. The data measurements were made at 13 stations within 12 sitegrids scattered throughout the FIFE study area. Values for incoming longwave radiation were calculated using the radiometer chopper or detector temperature as a measure of air temperature. When determining surface temperatures from infrared thermometer measurements of the surface, the surface emissivity and the reflected component must be taken into account. The reflected component is dependent on the surface emissivity and the incoming longwave radiation.