Advances in Earth Radiation Budget Observations from Ceres Terra

The goal of the Clouds and the Earth's Radiant Energy System (CERES) project is to provide a long-term record of radiation budget at the top-of-atmosphere (TOA), within the atmosphere, and at the surface with consistent cloud and aerosol properties at climate accuracy [1]. CERES consists of an integrated instrument-algorithm-validation science team that provides development of higher-level products (Levels 1-3) and investigations. It involves a high level of data fusion, merging inputs from 25 unique input data sources to produce 18 CERES data products. Over 90% of the CERES data product volume involves two or more instruments. At the heart of the CERES project are the CERES instruments. Thus far, five CERES instruments (PFM, FM1-FM4) have flown on three different spacecraft: TRMM, EOS-Terra and EOS-Aqua. CERES FM5 is scheduled for launch on the NPP spacecraft, and FM6 will fly on NPOESS C1. Each CERES instrument is a scanning broadband radiometer that measures filtered radiances in the SW (wavelengths between 0.3-5 m), total (TOT) (wavelengths between 0.3-200 m) and WN (wavelengths between 8-12 m) regions. On Terra, CERES has a spatial resolution of approximately 20 km (equivalent diameter). the filtered radiances to unfiltered reflected solar, unfiltered emitted terrestrial LW and WN radiances [2]. These are then used to determine SW, LW and WN TOA radiative fluxes by applying Angular Disitrbution Models (ADMs) [3] constructed from two years of CERES Terra biaxial scan data using MODIS cloud property retrievals for scene identification [4]. MODIS cloud and aerosol retrievals, meteorological data from the Global Modeling and Assimilation Office—Goddard Earth Observing System Model, and aerosol assimilation data from the Model of Atmospheric Transport and Chemistry (MATCH) are used as input to a modified version of the [5] radiative transfer code to provide computed SW, LW and net radiative fluxes at several levels within the atmosphere and at the surface. Surface radiative fluxes are also estimated using simpler parameterizations [6]. In order to account for diurnal variations in clouds and radiation, the CERES and MODIS observations on Terra are combined with data from five geostationary instruments to produce 1°1° gridded TOA, within-atmosphere and surface radiative fluxes at 3-hourly, daily, and monthly time scales. Considerable effort is spent on verifying the consistency of the many instruments and inputs to ensure that the CERES data product reflect real changes in the climate system as opposed to artificial changes associated with the input data.