Abstract
The Clouds and Earth’s Radiation Energy System (CERES) program produces data of solar-reflected and earth-emitted radiation from the top-of-atmosphere (TOA), within the atmosphere, and at the Earth’s surface. This program currently employs six instruments onboard four different spacecraft to measure and produce long-term record of the earth’s energy budget. CERES Flight Model 6 (FM6), the instrument that will fly on the Joint Polar Satellite System (JPSS) -1 spacecraft, is a scanning broadband radiometer consisting of three sensors that measure three different spectral radiances: solar region consisting of wavelength between 0.3 to 5 microns, total region between 0.3 to 200 microns, and a broadband region of 5 to 40 microns. Rigorous pre-launch ground calibration is performed on these sensors to meet accuracy requirements of 1% and 0.5% for shortwave and longwave radiance observations, respectively.
A Cryogenically cooled Transfer Active Cavity Radiometer (TACR), one of the components of the pre-launch ground calibration facility, was modified in efforts to improve traceability within the reflected solar bands (shortwave and total channels). These modifications included replacing the heritage mirrors from enhanced silver coating to protected aluminum, which in turn resulted in a greater signal-to-noise ratio. These findings along with efforts to quantify the spectral response of the new TACR’s optics from UV to IR are discussed in this paper.
Enhancing the Ground Calibration in the Short-wavelength Region to Improve Traceability within the Reflected Solar Bands of the CERES Instrument
The Clouds and Earth’s Radiation Energy System (CERES) program produces data of solar-reflected and earth-emitted radiation from the top-of-atmosphere (TOA), within the atmosphere, and at the Earth’s surface. This program currently employs six instruments onboard four different spacecraft to measure and produce long-term record of the earth’s energy budget. CERES Flight Model 6 (FM6), the instrument that will fly on the Joint Polar Satellite System (JPSS) -1 spacecraft, is a scanning broadband radiometer consisting of three sensors that measure three different spectral radiances: solar region consisting of wavelength between 0.3 to 5 microns, total region between 0.3 to 200 microns, and a broadband region of 5 to 40 microns. Rigorous pre-launch ground calibration is performed on these sensors to meet accuracy requirements of 1% and 0.5% for shortwave and longwave radiance observations, respectively.
A Cryogenically cooled Transfer Active Cavity Radiometer (TACR), one of the components of the pre-launch ground calibration facility, was modified in efforts to improve traceability within the reflected solar bands (shortwave and total channels). These modifications included replacing the heritage mirrors from enhanced silver coating to protected aluminum, which in turn resulted in a greater signal-to-noise ratio. These findings along with efforts to quantify the spectral response of the new TACR’s optics from UV to IR are discussed in this paper.