Field comparisons of direct and component measurements of net radiation under clear skies

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Journal of Applied Meteorology

DOI:https://doi.org/10.1175/1520-0450(1994)033<0245:FCODAC>2.0.CO;2· OSTI ID:146938

Duchon, C L ^[1]; Wilk, G E ^[2]

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1. Univ. of Oklahoma, Norman, OK (United States)
2. National Weather Service, Corpus Christi, TX (United States)

Accurate measurements of net radiation are basic to all studies of the surface energy budget. In preparation for an energy budget experiment significant differences were found between direct and component measurement of net radiation, which prompted this investigation of their cause. The instruments involved were an all-black single-dome Fritschen-type net pyrradiometer, two Eppley model 8-48 pyranometers, and an Eppley model PIR pyrgeometer. Each had recently been calibrated. The accuracy of the component instruments was considered first. Comparisons of about one hour on each of three nights between the pyrgeometer and five empirical formulas showed that the average departure over all formulas from the pyrgeometer average was {minus}1%. Other comparisons between the pyrgeometer and an infrared thermometer viewing the surface yielded similar results. Alternate shading and unshading of the pyrgeometer looking upward during daytime resulted in a formula that was used to correct the downward longwave radiation under clear skies. The correction is dependent on wind speed, in contrast to a recent paper showing negligible dependence, but is in accord with earlier findings. Based on manufacturer`s specifications, the pyranometer calibrations were considered to be within 2% of the World Radiation Reference. Thus a series of experiments was carried out using what were believed to be reasonably accurate component measurements of net radiation and measurements from the net pyrradiometer.

• Sponsoring Organization: USDOE
• OSTI ID: 146938
• Journal Information: Journal of Applied Meteorology, Journal Name: Journal of Applied Meteorology Journal Issue: 2 Vol. 33; ISSN JOAMEZ; ISSN 0894-8763
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
54 ENVIRONMENTAL SCIENCES
ACCURACY
ATMOSPHERIC CHEMISTRY
HOURLY VARIATIONS
MEASURING INSTRUMENTS
MEASURING METHODS
PYRANOMETERS
RADIANT HEAT TRANSFER
SENSITIVITY
SOILS
SOLAR RADIATION
WIND