Continuous monitoring of the Earth's Radiation field at the top of the atmosphere (TOA) is essential for understanding climate and climate variability on Earth. To achieve this important science goal, the National Aeronautic and Space Administration (NASA) has begun the Clouds and the Earth's Radiant Energy System (CERES) project, which consists of Earth radiation budget instrument packages flying on three different satellites, beginning with Tropical Rainfall Measuring Mission (TRMM) satellite in November 1997, the Earth Observing System (EOS) Terra spacecraft in December 1999, and the EOS Aqua satellite in spring/summer 2002. Building on the successful Earth Radiation Budget Experiment (ERBE) project, this multi-satellite Earth Radiation budget mission will provide the scientific community with necessary information for monitoring and understanding the Earth's radiation environment well into the 21th century.

After two months of initial routine checkup, the two CERES instruments installed aboard the NASA EOS Terra spacecraft begin taking scientific observations on February 26, 2000. They have since provided global broadband radiation measurements for over 22 months. This paper will present results of radiation budget analyses from the first year of the CERES/Terra operation. Results will include regional, zonal, and global analyses of outgoing longwave radiation, reflected solar radiation, net radiation, and cloud radiative forcings over various timescales. In addition, tropical mean outgoing longwave radiation will also be shown along with results from CERES/TRMM and other historical broadband radiation datasets to illustrate the long term variability of the tropical mean longwave radiation budget.