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The Clouds and the Earth's Radiant Energy System (CERES) experiment is one of the highest-priority scientific satellite instruments developed for NASA's Earth Observing System (EOS) and continues through the Joint Polar Satellite System (JPSS). CERES is a key component of the Earth Observing System (EOS) program and serves as a follow-on to the successful Earth Radiation Budget Experiment (ERBE) mission.

There have been seven operational CERES instruments:

  • The first CERES instrument, Proto-Flight Model (PFM) was launched on November 27, 1997 as part of the completed Tropical Rainfall Measuring Mission (TRMM).
  • Two CERES instruments, Flight Models 1 and 2 (FM1 and FM2) were launched into polar orbit on board the EOS flagship Terra on December 18, 1999. FM2 ceased operations on January 10, 2025.
  • Two additional CERES instruments, FM3 and FM4, were launched on board EOS Aqua on May 4, 2002.
  • CERES instrument, FM5, was launched on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite on October 28, 2011.
  • The final CERES instrument, FM6, was launched on board the National Oceanic and Atmospheric Administration's (NOAA) Joint Polar Satellite System 1 (JPSS-1, now NOAA-20) satellite on November 18, 2017.

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.

CERES website

Instrument Type

Spectrometers/Radiometers

Instrument Subtype

Radiometers

Specifications

Resolution

Spatial
  • 10 km (PFM)
  • 20 km (FM1-FM4)
  • 24 km (FM5-FM6)
Spectral
  • Shortwave: 0.3-5 µm 
  • Total: 0.3-200 µm 
  • Window: 8-11 µm (PFM, FM1-FM5)
  • Longwave: 5-35 µm (FM6)
Temporal
  • Daily

Platforms

Terra

Launch Date
December 18, 1999
Altitude
705 km
Inclination
98.5°

Aqua

Launch Date
May 4, 2002
Altitude
705 km
Inclination
98.2°

Related Data Centers/Projects

ASDC

NASA's Atmospheric Science Data Center focuses on Earth science disciplines including radiation budget, clouds, aerosols, and tropospheric composition.

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