选用兰州大学半干旱气候与环境观测站2006年9月1日至2007年8月31日的光度计观测资料，以及同期的地面常规观测资料、卫星资料和探空资料，结合冗长绝对法对太阳光度计进行Langley定标。结果表明：选用某一天认为符合条件的观测日定标，其结果误差可能会较大；对各波段的多日定标值直接取平均，计算结果与真值的差别仍会较大；采用期望平均法和拟合平均法检验筛选后，日定标值的离散程度会显著减小，标准差减小了70％～90％；拟合平均法剔除偏离较大的散点后定标值的平均值更接近于真值。

Langley plot method and long-winded absolute method are used to calibrate sunphotometer. It is based on the obserbational data of sunphotometer obtained from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during the period from 1 September, 2006 to 31 August, 2007, homochronous surface conventional observation data, satellite data and radiosonde data. The results show that the error of scaling value may be large when selecting one eligible observation day. If the scaling value of several days in each band is averaged, the calibrate error between calculated and truth value will be still large. If the method of expected mean method and fitted mean method are screened, the scatter degree of daily scaling value will strikingly decrease and the standard deviation can be reduced by 70%~90%; After spots which deviate relatively distantly are deleted by using fitted mean method, the averge scaling value is close to the truth value.