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CERES Brochure


 

CERES Introduction Image   ". . . the science of Nature has been already too long made only a work of the brain and the fancy; It is now high time that it should return to the plainness and soundness of observations . . ."

-- Robert Hooke (1635-1703)

NASA's Earth Observing System (EOS) is part of an international program for studying the Earth from space using a multiple-instrument, multiple-satellite approach. This EOS program is critical for improving our scientific understanding of ongoing natural and human-induced global climate change and providing a sound scientific basis for developing global environmental policies.

The Clouds and the Earth s Radiant Energy System (CERES) experiment is one of the highest priority scientific satellite instruments developed for EOS. CERES products include both solar-reflected and Earth-emitted radiation from the top of the atmosphere to the Earth's surface. Cloud properties are determined using simultaneous measurements by other EOS instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS). Analyses of the CERES data, which build upon the foundation laid by previous missions such as the Earth Radiation Budget Experiment (ERBE) link to external site, will lead to a better understanding of the role of clouds and the energy cycle in global climate change.

CERES instruments were launched aboard the Tropical Rainfall Measuring Mission (TRMM) link to external site in November 1997 and on the EOS Terra satellite in December 1999. Two additional instruments will fly on the EOS Aqua spacecraft in 2002. Multiple satellites are needed to provide adequate temporal sampling since clouds and radiative fluxes vary throughout the day. The first 24 months of CERES data collected on both TRMM and Terra demonstrate that the CERES instruments are substantially improved over the ERBE instruments. The CERES data show lower noise, improved ties to the ground calibration in absolute terms, and smaller fields of view. CERES instrument calibration stability on TRMM and Terra is typically better than 0.2%, and calibration consistency from ground to space is better than 0.25%. Onboard calibration sources provide traceability of the measurements to the International Temperature Scale of 1990 at the 0.2% level. Such levels of accuracy have never before been achieved for radiation budget instruments.



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  Image: NASA Logo NASA Official: Dr. Norman Loeb
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