A New Look at Calibration and Use of Eppley Precision Infrared Radiometers. Part I: Theory and Application
Open Access
- 1 December 1998
- journal article
- Published by American Meteorological Society in Journal of Atmospheric and Oceanic Technology
- Vol. 15 (6) , 1229-1242
- https://doi.org/10.1175/1520-0426(1998)015<1229:anlaca>2.0.co;2
Abstract
The calibration and accuracy of the Eppley precision infrared radiometer (PIR) is examined both theoretically and experimentally. A rederivation of the fundamental energy balance of the PIR indicates that the calibration equation in common use in the geophysical community today contains an erroneous factor of the emissivity of the thermopile. If a realistic value (0.98) for the emissivity is used, then this leads to errors in the total flux of 5–10 W m−2. The basic precision of the instrument is found to be about 1.5% of the total IR irradiance when the thermopile voltage and both dome and case temperatures are measured. If the manufacturer’s optional battery-compensated output is used exclusively, then the uncertainties increase to about 5% of the total (20 W m−2). It is suggested that a modern radiative transfer model combined with radiosonde profiles can be used as a secondary standard to improve the absolute accuracy of PIR data from field programs. Downwelling IR fluxes calculated using the ... Abstract The calibration and accuracy of the Eppley precision infrared radiometer (PIR) is examined both theoretically and experimentally. A rederivation of the fundamental energy balance of the PIR indicates that the calibration equation in common use in the geophysical community today contains an erroneous factor of the emissivity of the thermopile. If a realistic value (0.98) for the emissivity is used, then this leads to errors in the total flux of 5–10 W m−2. The basic precision of the instrument is found to be about 1.5% of the total IR irradiance when the thermopile voltage and both dome and case temperatures are measured. If the manufacturer’s optional battery-compensated output is used exclusively, then the uncertainties increase to about 5% of the total (20 W m−2). It is suggested that a modern radiative transfer model combined with radiosonde profiles can be used as a secondary standard to improve the absolute accuracy of PIR data from field programs. Downwelling IR fluxes calculated using the ...Keywords
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