Diurnal, seasonal, and interannual variations of cloud properties derived for CERES from Imager data

Simultaneous measurement of the radiation and cloud fields on a global basis has long been recognized as a key component in understanding and modeling the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth’s Radiant Energy System (CERES) Project begun in 1998 is meeting this need. Broadband shortwave and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth from the TRMM Visible Infrared Scanner and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. In addition to aiding the interpretation of the broadband radiances, the CERES cloud properties are valuable for understanding cloud variations at a variety of scales. In this paper, the resulting CERES cloud data taken to date are averaged at several temporal scales to examine the diurnal, seasonal, and interannual variability of the cloud properties on a global scale at a 1° resolution. The results are compared to trends and averages of similar parameters from surface data and other satellite analyses such as ISCCP and SAGE.