Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
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The Dome Emission Effect on the Performance of Pyrgeometers with Silicon Domes
Masataka ShiobaraShoji Asano
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1992 Volume 43 Issue 1 Pages 17-31

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Abstract
   The dome emission effect of Eppley pyrgeometers, PIRs, was quantitatively investigated by laboratory experiments with a newly developed calibration apparatus and by field measurements under clear and cloudy conditions. The calibration apparatus contained a blackbody to provide homogeneous thermal radiation at a variable temperature between -25°C and room temperature and also a device to change the dome temperature. The dome coefficients of PIRs were obtained by laboratory experiments with the apparatus. Hysteresis of PIR outputs disappeared successfully after correction of the dome emission effect, and the linear regression for the PIR output versus the radiation input had a straight line giving calibration constants for the PIRs.
   Errors involved in the laboratory experiment and the field measurement were estimated. When the downward infrared flux was measured with PIRs, ground-based measurements under the clear sky overestimated by more than 20W/m2 unless the dome emission effect was eliminated. By the contrary effect, airborne measurements underestimated by 10-20W/m2. It is shown that PIRs can measure infrared radiative flux with an error around 10W/m2 if the dome temperature is measured in order to correct the dome emission effect.
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© 1992 by Japan Meteorological Agency / Meteorological Research Institute
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