Determination and validation of slow mode coefficients of the Clouds and the Earth's Radiant Energy System (CERES) scanning thermistor bolometers

The Clouds and the Earth's Radiant Energy System (CERES) scanning thermistor bolometers have a response time of approximately 9 ms for 98 to 99% of the signal, after which there is a slow change for the remaining 1 to 2% of the response due to a slow mode. This paper describes the theoretical and experimental procedures used in producing the slow mode coefficients for the CERES Flight Models 1 and 2 instruments aboard the Terra spacecraft, which was launched on December 18, 1999. The response behavior for the total thermistor bolometer (0.3 - > 100 mum) acid window channel (8-12 mum) were determined by analyzing the internal blackbody calibration ground data while the shortwave thermistor bolometer (0.3 - 5 mum) was determined using shortwave internal calibration source ground data obtained at the TRW calibration facility at Redondo Beach, California. These slow mode coefficients agree with the coefficients obtained by analyzing the in-flight calibration data. A numerical filter removes the effects of the slow mode from the measurements. The method may be applicable to other instruments which have spurious transients.