A Novel Constant-Chopper Scanning Radiometer

70697 The DOE¿s mission to expand our understanding of climate and climate change drives the need for improved measurement of radiation from the sun, clouds, and atmosphere. The absolute accuracy of field radiometers such as pyrgeometers and shaded pyranometers is undetermined because the DOE has no reference instrument with which to compare. Related needs include the determination of cirrus cloud temperature for use with millimeter radar and measurement of local nighttime cloud cover. The latter also applies to the FAA and airport safety. This project will apply an innovative optical configuration in a scanning radiometer designed to provide reference measurements of diffuse infrared sky irradiance. The instrument also will measure cloud and sky brightness temperature, and allow the determination of cloud cover at night. Phase I will consist of modeling and analysis to quantify and minimize all sources of error in the proposed instrument. A simple prototype will be developed for testing and verification. The feasibility of using the same instrument to measure diffuse shortwave radiation will also be examined. Commercial Applications and Other Benefits as described by the awardee: The first application of the proposed instrument would be by the DOE and other governmental agencies for global radiation measurement. In addition, a large commercial market should exist in aviation for the nighttime determination of cloud cover.