Standard spectrophotometric facility for ensuring the unity of measurements of meteorological optical range

The results of creating a system for metrological traceability of the results of measurements of the meteorological optical range by transmissionmeters and nephelometers to the state primary standard in the Russian Federation are presented. To solve the problems of realization, maintenance and dissemination of the unit of luminous transmittance to meteorological optical range meters by the transmissometer method, a specialized spectrophotometric facility equipped with a set of large-diameter (140 mm) standard neutral light filters has been developed and created. The created facility is included in the State primary standard of units of color coordinates, chromaticity coordinates, and luminous transmittance, GET 81-2023. Meteorological optical range characterizes the visibility range in the atmosphere, due to the absorption and scattering of optical radiation. The value of meteorological optical range is directly related to the luminous transmittance of atmospheric air. 

Thus, the unity of measurements of meteorological optical range must be ensured by the traceability of the meters of the luminous transmittance coeffi cient of atmospheric air to the State Primary Standard. The facility realizes the unit of luminous transmittance in the absolute value range from 0.027 to 0.993 with combined standard uncertainty of 0.00042. Large-diameter standard fi lters allow to disseminate the unit of luminous transmittance to transmissometers intended to measure the luminous transmittance of atmospheric air in natural conditions and realize the scale of meteorological optical range. The nephelometric measurement method and the dissemination of the unit of meteorological optical range to nephelometers are described. The created facility heads the State Verifi cation Scheme and ensures traceability to GET 81-2023 of meteorological optical range measuring instruments used in meteorology, air travel safety systems, shipping, and road management.

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