为进一步提高紫外臭氧垂直探测仪(SBUS)在轨探测及数据反演精度，提出了SBUS地面定标的一系列改进方案，其中为实现地面定标与在轨工作环境一致的全波段真空辐射定标是改进的第一项。通过构建SBUS大气/真空光谱辐照度响应度比对测试装置，实测了两种环境下SBUS整机对同一光源的光谱辐照度响应。结果显示，在250~300 nm波段，真空/大气相对偏差约0.8%；在300~400 nm波段，真空/大气比对结果随波长变化，最大偏差略高于15%。而仪器250~400 nm波段定标环境引入的单项不确定度，真空定标比以往大气定标减小了1.8%。理论分析及实验验证后发现SBUS反射元件Al+MgF2膜层在真空/大气下光谱反射率会发生变化，从而证实了SBUS在真空环境下定标的必要性。

A group of improving methods for the on-ground calibration of solar backscattered ultraviolet spectroradiometer (SBUS) has been put forward to increase its precision of on-board detection and data inversion. The full-waveband radiometric calibration in vacuum, which can attain correspondence match of condition between on-ground calibration and on-board detection, is the first item. A spectral irradiance responsibility comparing measurement setup is built and the spectral irradiance response of SBUS to a same source is measured in air and vacuum, respectively. The result shows a 0.8% relative deviation between air and vacuum in 250~300 nm and a wavelength dependent deviation, among which the maximum is a little more than 15%, in 300~400 nm. The individual uncertainty caused by calibration condition of SBUS in vacuum is 1.8% smaller than that in air. After theoretical analysis and confirmatory testing, it is found that the spectral reflectivity of Al+MgF2 coating of SBUS reflecting element would be different in air and in vacuum, which proves the necessity of SBUS calibration in vacuum condition.