Instrument Detectors

The CERES instrument contains three detectors:

• One that measures the total returned energy (0.3 - 200 μm)
• Another that captures shortwave energy (0.3 – 5.0 μm)
• The last that measures infrared energy in the window channel (8 – 12 μm)

Note: The last CERES instrument, FM6 on NOAA-20, includes a longwave detector (5 - 35 μm) instead of the window channel.

Operational Modes and Advantages

Flying multiple satellites concurrently reduces the risk of a climate data record gap and provides adequate temporal sampling since clouds and radiative fluxes vary throughout the day. Having two instruments on one satellite allows operating one in cross-track mode for climate products and the other in a rotating azimuth plane to develop angular distribution models to adjust for anisotropy or allow validation with other instruments.

Performance and Calibration

The CERES instruments show significant improvements over the ERBE instruments, including lower noise, improved ties to ground calibration in absolute terms, and smaller fields of view. Calibration stability is typically better than 0.2% for all CERES instruments. Onboard calibration sources provide traceability to the prelaunch calibration of the CERES sensors tied to the International Temperature Scale of 1990.