Abstract
Libera is a next generation scanning radiometer that will fly as a rideshare on the Joint Polar Satellite System-3 (JPSS-3), which is set to launch in late 2027. Libera will provide continuity of the Clouds and Earth’s Radiant Energy System (CERES) Earth radiation budget observations, advance the development of a self-contained observing system, and provide enhanced observing capability to further support earth radiation budget science goals. Data collected by Libera will be used by the earth radiation budget community to continue the long-term measurements of radiation being reflected and emitted by Earth. The Libera science channels include shortwave (SW; 0.3-5 μm) to measure solar radiation reflected by the Earth, longwave (LW; 5-50 μm) to measure IR radiation emitted from Earth, and total (TOT; 0.3- 100+ μm) to measure the total radiation being reflected and emitted by Earth. In addition to these three channels shared with CERES, there will be a new science channel, the split short-wave channel (SSW; 0.7-5 μm) to further quantify the shortwave energy deposition in the Earth system, and a wide field of view camera for scene identification and split-SW angular distribution model development. On-board calibration sources will be used to track changes in the science radiometers over the planned five-year mission. These calibration sources include a short-wave LED-based calibration system and a reflective Spectralon solar diffuser, used to track degradation of all four science channels. A black body source will be used to track degradation of the LW and TOT channels. In addition to the on-board sources, Libera will use the moon 8-12 times per year as an independent calibration check. Each calibration source has independent traceability. Drifts among the sources will not be correlated and stability across the sources will verify the stability of the science radiometers. This paper highlights the planned onorbit calibration operations including a detailed discussion of the different calibration targets.
Libera On-Orbit Calibration
Libera is a next generation scanning radiometer that will fly as a rideshare on the Joint Polar Satellite System-3 (JPSS-3), which is set to launch in late 2027. Libera will provide continuity of the Clouds and Earth’s Radiant Energy System (CERES) Earth radiation budget observations, advance the development of a self-contained observing system, and provide enhanced observing capability to further support earth radiation budget science goals. Data collected by Libera will be used by the earth radiation budget community to continue the long-term measurements of radiation being reflected and emitted by Earth. The Libera science channels include shortwave (SW; 0.3-5 μm) to measure solar radiation reflected by the Earth, longwave (LW; 5-50 μm) to measure IR radiation emitted from Earth, and total (TOT; 0.3- 100+ μm) to measure the total radiation being reflected and emitted by Earth. In addition to these three channels shared with CERES, there will be a new science channel, the split short-wave channel (SSW; 0.7-5 μm) to further quantify the shortwave energy deposition in the Earth system, and a wide field of view camera for scene identification and split-SW angular distribution model development. On-board calibration sources will be used to track changes in the science radiometers over the planned five-year mission. These calibration sources include a short-wave LED-based calibration system and a reflective Spectralon solar diffuser, used to track degradation of all four science channels. A black body source will be used to track degradation of the LW and TOT channels. In addition to the on-board sources, Libera will use the moon 8-12 times per year as an independent calibration check. Each calibration source has independent traceability. Drifts among the sources will not be correlated and stability across the sources will verify the stability of the science radiometers. This paper highlights the planned onorbit calibration operations including a detailed discussion of the different calibration targets.