辐射定标是光学卫星传感器遥感信息定量化的关键技术之一。基于多灰阶靶标的星载多光谱相机在轨绝对辐射定标方法, 以地面漫射辐射/总辐射比、大气光学厚度等参数的实际测量代替气溶胶散射特性假设, 通过参照目标反射辐射与大气程辐射及地气耦合辐射的分离, 简化定标流程, 并突破大面积辐射校正场受时空条件的限制, 实现高分辨率多光谱遥感器全动态范围内的高精度、高频次、业务化定标。试验结果表明: 基于灰阶靶标的高分辨光学卫星传感器在轨绝对辐射定标不确定度优于3.5%, 与反射率基法定标结果的差异优于5%, 且适应于复杂环境条件下在轨定标的应用需求。

Radiometric calibration in-flight is one of critical techniques for information quantification of optical satellite sensor. A calibration approach based on gray-scale targets has been presented. It substitutes the measured ratio of diffusion to global irradiance and atmospheric optical depth to the assumption of aerosol scatter. And the method could isolate the DN signal created by the targets from the response produced by background radiance sources, which simplify the calibration process. It can break the time and locale conditions limit of radiometric sites and achieve high precision, high frequency and normalizable calibration application for high spatial resolution multi-spectral sensor with full dynamic range. The results show that the calibration approach′s uncertainty is less than 3.5%. And the difference of calibration coefficient is less than 5% compared with the reflectance-based method. Simultaneously, this approach can also satisfy the application to the complex environment.