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Longwave radiation at the ground: III. A radiometer for the ‘representative angle’
Author(s) -
Dalrymple G. J.,
Unsworth M. H.
Publication year - 1978
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710444010
Subject(s) - thermopile , radiometer , longwave , zenith , environmental science , radiation , optics , photometer , remote sensing , flux (metallurgy) , radiation flux , atmospheric sciences , physics , meteorology , infrared , materials science , geography , metallurgy
The construction of a directional radiometer for measuring longwave radiation from the atmosphere is described. The instrument had a filter of black polyethylene to exclude solar radiation, and the detector was a thermopile. By analysis of the radiation and heat balances of the thermopile, correction terms are derived for (i) the flux density of radiation received by the thermopile from the filter, and (ii) the dependence of instrument sensitivity on temperature. Measurements with the new instrument of the equivalent flux density below cloudless skies at zenith angle 52.5° agree well with measurements of hemispheric flux density derived from simultaneous measurements with a Linke‐Feussner actinometer.