总辐射表夜间零点偏移试验与分析

Experiments and Analysis of Pyranometers on Nighttime Zero Offset

总辐射表夜间零点偏移试验在夜间晴天条件下,采用室外平行对比法对不同型号的总辐射表的零点进行测试。通过数据分析,分别比较了黑白型和全黑型总辐射表、国产与进口总辐射表夜间零点偏移的大小,并分析了形成零点偏移的原因。试验结果表明,在夜间晴天条件下国产总辐射表的零点偏移小于10 W·m^(-2)通过总辐射表感应面向下水平安装和加盖试验也验证了零点偏移确实是由"冷天空"所致。

The zero offset experiments for pyranometers were done outside in the night of clear day using the comparison method.On the basis of the experiments,the zero offsets of different pyranometers（the black-white pyranometers and all-black pyranometers,the homemade and imported pyranometers） were compared respectively.The causes for zero offset were analyzed.By analysis of the experimental data,it was shown that the zero offset of the homemade pyranometers was less than 10 W·m^-2 in the night of clear day.The experiments,in which the sensing surface of pyrnaometers was installed downwards and a lid was put on the pyranometers,all demonstrated that the zero offset was caused by the cold sky effect indeed.