Absolute radiation scale: Difference between revisions
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[Abbreviated ARS; also referred to as the World Radiation Reference (WRR).] A [[radiation]] scale for measurement of solar exitance ([[irradiance]]).<br/> Prior to 1956, the Ångström Scale (ÅS) (1905) and Smithsonian Scale (SS) (1913) were used. Each [[scale]] was calibrated against a different [[radiation]] detector (i.e., the [[Ångström compensation pyrheliometer|Ångström compensation pyrheliometer]] and water-stirred [[pyrheliometer]], respectively), and yielded slightly different values for the irradiance, with the ÅS reading roughly 3.5% lower than the SS. The [[International Pyrheliometric Scale|International Pyrheliometric Scale]] (IPS), defined in 1956, represented a numerical compromise between these two scales. In 1975, the IPS was replaced by the Absolute Radiation Scale (ARS). The ARS is calibrated against six [[absolute cavity radiometers]] maintained at the World Radiation Center in Davos, Switzerland. The [[variation]] among the six radiometers is about 0.3%. The IPS was found to give measured irradiance levels that were about 2%–3% lower than the more precise ARS. | |||
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Revision as of 16:08, 7 November 2023
[Abbreviated ARS; also referred to as the World Radiation Reference (WRR).] A radiation scale for measurement of solar exitance (irradiance).
Prior to 1956, the Ångström Scale (ÅS) (1905) and Smithsonian Scale (SS) (1913) were used. Each scale was calibrated against a different radiation detector (i.e., the Ångström compensation pyrheliometer and water-stirred pyrheliometer, respectively), and yielded slightly different values for the irradiance, with the ÅS reading roughly 3.5% lower than the SS. The International Pyrheliometric Scale (IPS), defined in 1956, represented a numerical compromise between these two scales. In 1975, the IPS was replaced by the Absolute Radiation Scale (ARS). The ARS is calibrated against six absolute cavity radiometers maintained at the World Radiation Center in Davos, Switzerland. The variation among the six radiometers is about 0.3%. The IPS was found to give measured irradiance levels that were about 2%–3% lower than the more precise ARS.