Optical analysis of the ERBE scanning thermistor bolometer radiometer using the Monte Carlo method

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Virginia Tech

In 1984, the Earth Radiation Budget Experiment (ERBE) was started by the National Aeronautics and Space Administration (NASA) to provide data to the meteorological community to predict long-term weather and climate trends. Three satellites employing nonscanning active cavity and scanning thermistor bolometer radiometers are orbiting the Earth to monitor its radiative emission. A numerical model has been formulated to better understand the performance of the ERBE scanning radiometer and to aid future radiometric design and calibration procedures.

The Monte Carlo method is applied to the ERBE scanning radiometer to spectrally characterize its optical and radiative performance. The optical analysis reveals that the ERBE scanning radiometer design successfully limits the amount of energy that reaches the active sensor to the designated instrument field of view. Distribution factors between the diffuse-specular surfaces of the scanning radiometer are calculated using the Monte Carlo method and are then used to perform the radiative analysis. This analysis shows that less than three percent of the radiation emitted from the passive surfaces of the radiometer reaches the active sensor, an acceptable level for radiometric instrumentation used in space.