Calibration System of Sunshine Duration Recorder Based on Bi-Xenon Lamp Source Integrating Sphere

Given the environmental influence, poor repeatability, and low efficiency of the outdoor calibration of the rotating pyroelectric sunshine duration recorder (RPSDR), an indoor calibration method using RPSDR with a system of the bi-xenon lamp source integrating sphere was proposed. According to the composition, structure, and measurement principle of the RPSDR, a calibration system based on the bi-xenon lamp source integrating sphere with the xenon lamp solar simulator outputting direct radiation and the dome xenon lamps simulating diffuse radiation was designed by technologies such as solar simulation and environmental simulation with the integrating sphere. The structural parameters of the integrating sphere were putforward, and the irradiance distribution and spectral correction of the xenon lamp source were analyzed. A comprehensive RPSDR calibration method for indoor sunshine threshold calibration and outdoor sunshine duration verification was established. According to the tests, the irradiance uniformity on the effective irradiation surface of the calibration system was 2.5% with the center point and 1. 6% without the center point. On the effective irradiation surface, the irradiance stability per hour at the threshold point was 0. 680%, and the light source matched with the AM1. 5 class A solar spectral energy distribution. Experiments of indoor threshold calibration and outdoor sunshine duration comparison were carried out on an RPSDR. The results show that the relative error of sunshine duration measured with the RPSDR after calibration is less than 1% and the absolute error is no more than 0. 26 h compared with the reference values measured with the pyrheliometer, which meet the requirements of the meteorological industry for sunshine duration observation.