A Narrow-Beam Radiometer for Atmospheric Radiation Studies

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  • 1 Division of Atmospheric Physics, CSIRO, Aspendale, Victoria, Australia
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Abstract

The design and performance of a narrow-beam radiometer for atmospheric studies are described. It has a beamwidth of 6 mrad and a minimum detectable radiance of 0.0056 mW cm−2 sr−1 in a 1-HZ output bandwidth. The system incorporates a novel method of comparing flux incident on the aperture against a temperature-stabilized blackbody so that effects due to variations in radiation emitted by or reflected from the chopper blades are eliminated. The radiometer is being applied initially to studies in the 10–12 μm spectral band of the atmospheric “window”. Several applications, including the study of water vapor continuum absorption and the emissivity of high layer clouds, are described briefly.

Abstract

The design and performance of a narrow-beam radiometer for atmospheric studies are described. It has a beamwidth of 6 mrad and a minimum detectable radiance of 0.0056 mW cm−2 sr−1 in a 1-HZ output bandwidth. The system incorporates a novel method of comparing flux incident on the aperture against a temperature-stabilized blackbody so that effects due to variations in radiation emitted by or reflected from the chopper blades are eliminated. The radiometer is being applied initially to studies in the 10–12 μm spectral band of the atmospheric “window”. Several applications, including the study of water vapor continuum absorption and the emissivity of high layer clouds, are described briefly.

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