Continuous monitoring the Earth Radiation Budget (ERB) at top of the atmosphere is essential for understanding climate and climate change. To achieve this important science goal, the National Aeronautics and Space Administration (NASA) has begun the Clouds and the Earth's Radiant Energy System (CERES) Mission, which consists of ERB instrument packages flying on three different satellites. After two months of initial routine checkup, the two CERES instruments installed aboard the NASA Earth Observing System (EOS) Terra spacecraft begin taking scientific observations on February 26, 2000. They have since provided global broadband measurements of outgoing longwave radiation (OLR) and of reflected solar radiation (RSR) from the Earth for over 3 years.

This paper will present preliminary comparisons of the intraseasonal variability, defined as variations with period of 20 to 60 days, of OLR and RSR deduced from the first year of CERES/Terra observations against those derived from the NOAA/NCEP Reanalysis 2 system during the same data period. The observed intraseasonal variations of OLR and RSR show many interesting/important regional patterns that are associated with physical processes that operate well beyond the traditional weather time-scale. These regional features are well organized and should be, in principle, reproducible by global models. While the NCEP Reanalysis 2 modeled intraseasonal variations of OLR show good spatial agreements with observations, the dynamic range of the modeled variability is smaller than those of CERES/Terra observations; suggesting some deficiencies in modeling the intraseasonal processes that generated these OLR fields. Furthermore, the modeled intraseasonal variations of RSR, in general, do not agree with observations; indicating additional works are needed for improving the physical processes that generate these shortwave radiation fields.