Surface reflectance is one of the key parameters used in automated vicarious calibration. Two ground-viewing radiometers are used to measure the surface reflectance in Dunhuang; however, the radiometers degrade over time. A transfer radiometer is used to determine the trends on site. Before the transfer radiometer is used to correct the ground-viewing radiometer, one should perform an absolute radiometric calibration. Three methods are used to calibrate the transfer radiometer and utilize an intercomparison. The difference between the three methods is small. The uncertainty of each method is analyzed and found to be less than 6% at two standard deviations. Two ground-viewing radiometers are corrected by the transfer radiometer, and the degradation of most channels is less than 5%. The good performance achieved in the field indicates that the three methods are viable for calibrating a field transfer radiometer.

表面反射率是自动替代校准中使用的关键参数之一。敦煌市使用了两个地面辐射计来测量表面反射率。但是，辐射计会随着时间而退化。传输辐射计用于确定现场趋势。在使用转移辐射计校正地面辐射计之前，应先进行绝对辐射度校准。三种方法用于校准传输辐射计并利用比对。三种方法之间的差异很小。分析每种方法的不确定度，发现在两个标准偏差下小于6％。两台地面辐射计通过传输辐射计进行了校正，大多数通道的衰减小于5％。