<title>Design and calibration features of the clouds and the earth's radiant energy system (CERES) instrument</title>

The clouds and the earth's radiant energy system (CERES) instrument has been developed based on the earth radiation budget experiment (ERBE). The CERES instrument will be flown on the Tropical Rainfall Measurement Mission and on the first two Earth Observation System platforms. The techniques which were used to calibrate the ERBE instruments on the ground and to maintain calibration in orbit to 1% precision are being refined and applied to the design and calibration of the CERES instrument. The same types of on-board calibration devices will be used for CERES as were used on ERBE to determine any changes in the sensors' responses. The TRW Radiometric Calibration Facility which was used for ERBE calibration has been upgraded for CERES by incorporation of a radiometrically characterized black body as a reference and a cryogenic active cavity radiometer as a calibration transfer device for the shortwave calibration system.