摘要: The Clouds and the Earth's Radiant Energy System (CERES) broadband shortwave channel, 0.3 - 5 micrometer, measures atmosphere and surface reflected solar radiation. CERES provides an in-flight tungsten lamp to monitor the shortwav... 展开 The Clouds and the Earth's Radiant Energy System (CERES) broadband shortwave channel, 0.3 - 5 micrometer, measures atmosphere and surface reflected solar radiation. CERES provides an in-flight tungsten lamp to monitor the shortwave radiometric stability over the lifetime of the instrument. Initial Tropical Rainfall Measurement Mission (TRMM) tungsten calibration results indicate a 0.6% change over the first six months of mission life (Priestley et al. 1998). The three channel intercomparison technique and the solar diffuser calibration results show shortwave stabilities of 0.2% and 0.3% for the same time period (Priestley et al. 1998). Current belief is that the tungsten lamp, not the radiometer, has drifted. Radiometers, optics, and onboard calibrators exposed to the harsh space environment often degrade. Independent validation studies based on bright Earth viewing measurements are necessary to support the in-flight filtered calibration results. 收起