In 2017, PMOD/WRC organised the solar ultraviolet broadband radiometer comparison campaign UVC-II. All 75 participating instruments from all over the world were characterised in the laboratory of the World Calibration Center for UV (WCCUV) and calibrated outdoors relative to the Qasume reference spectroradiometer. After a three month calibration period, all devices were returned to their owners, accompanied by a certificate demonstrating traceability to the international system of units. The calibration uncertainty stated in these certificates was less than 6% for the majority of the radiometers. The deviation to the original calibration factors was analysed. From this data we determined three components affecting the overall measurement uncertainty of solar UV measurements using broadband radiometers on different time scales: Usage of additional correction factors to the absolute calibration factor, control of the humidity inside the device and recalibration frequency. A subset of radiometers participating in the campaign were calibrated and characterised at their home laboratories. A comparison of the calibration factors shows that the USER- and the WCCUV-calibrations agree within the uncertainties for 9 out of 11 calibrations.

中文翻译：

---

第二次太阳紫外线辐射计对比活动 UVC-II

2017年，PMOD/WRC组织了太阳紫外宽带辐射计对比活动UVC-II。来自世界各地的所有 75 台参与仪器都在世界紫外线校准中心 (WCCUV) 的实验室中进行了表征，并在室外相对于 Qasume 参考光谱仪进行了校准。经过三个月的校准期后，所有设备都归还给其所有者，并附有证明可追溯至国际单位系统的证书。对于大多数辐射计，这些证书中规定的校准不确定度小于 6%。分析了与原始校准因子的偏差。根据这些数据，我们确定了影响使用不同时间尺度的宽带辐射计进行太阳紫外线测量的整体测量不确定性的三个组成部分：对绝对校准系数使用额外的校正系数，控制设备内部的湿度和重新校准频率。参与该活动的一部分辐射计在其家庭实验室进行了校准和表征。校准因子的比较表明，用户校准和 WCCUV 校准在 11 次校准中的 9 次的不确定度范围内一致。