Radiometric performances of the Clouds and the Earth´s Radiant Energy System (CERES) instrument for the Tropical Rainfall Measuring Mission (TRMM) using in-flight calibration sources

Clouds and the Earth´s Radiant Energy System (CERES) instruments were designed to provide accurate measurements for the long-term monitoring of Earth´s radiation energy budget. The CERES instrument consists of three scanning thermistor bolometer sensors with built-in flight calibration systems. The three sensors measure the broadband radiances in the shortwave (0.3-5.0 μm), total (0.3->100 μm) and 8-12 μm water vapor window regions. The CERES sensors were calibrated using the internal calibration module sources within the Radiometric Calibration Facility at TRW, Redondo Beach, California, and in-flight on a biweekly basis. This paper discusses the in-flight calibration procedures for the CERES sensors. The radiometric performance results of the Proto-Flight Model CERES instrument on the ground and aboard the TRMM spacecraft during the first year of its mission life are also presented