Temporal Interpolation Methods for the Clouds and the Earth’s Radiant Energy System (CERES) Experiment

The Clouds and the Earth’s Radiant Energy System (CERES) is a NASA multisatellite measurement program for monitoring the radiation environment of the earth–atmosphere system. The CERES instrument was flown on the Tropical Rainfall Measuring Mission satellite in late 1997, and will be flown on the Earth Observing System morning satellite in 1998 and afternoon satellite in 2000. To minimize temporal sampling errors associated with satellite measurements, two methods have been developed for temporally interpolating the CERES earth radiation budget measurements to compute averages of top-of-the-atmosphere shortwave and longwave flux. The first method is based on techniques developed from the Earth Radiation Budget Experiment (ERBE) and provides radiation data that are consistent with the ERBE processing. The second method is a newly developed technique for use in the CERES data processing. This technique incorporates high temporal resolution data from geostationary satellites to improve modeling of diurnal variations of radiation due to changing cloud conditions during the day. The performance of these two temporal interpolation methods is evaluated using a simulated dataset. Simulation studies show that the introduction of geostationary data into the temporal interpolation process significantly improves the accuracy of hourly and daily radiative products. Interpolation errors for instantaneous flux estimates are reduced by up to 68% for longwave flux and 80% for shortwave flux.