In-flight stability analyses applied to the Clouds and the Earth's Radiant Energy System scanning thermistor bolometer instruments on the Terra satellite

Abstract

Clouds and the Earth's Radiant Energy System (CERES) is an investigation into the role of clouds and radiation in the Earth's climate system. Two CERES scanning thermistor bolometer instruments are aboard the Earth Observing System (EOS) Terra satellite that was launched 18 December 1999. Each CERES instrument has three sensors that measure in distinct broadband radiometric regions: the shortwave channel (0.3 - 5.0 μm), total channel (0.3 - greater than 100 μm), and window channel (8 - 12 μm). Two analyses have been implemented to aid in monitoring the stability of the measurements of the instruments. One analysis is a three-channel inter-comparison of the radiometric measurements for each instrument. This procedure derives an estimate of the shortwave portion of the total channel sensor radiance measurement. The second analysis is a direct comparison of temporally synchronized nadir measurements for each sensor of the two instruments. Use of these analyses indicates that the shortwave region of the measurements is drifting over mission lifetime for both instruments. A discussion of correcting the shortwave drift using ground software is included.