珠海一号欧比特高光谱数据交叉辐射定标初探

搭载于“珠海一号”卫星星座的欧比特高光谱OHS（Orbit Hyper Spectral）传感器，以较高的光谱分辨率和空间分辨率，在近岸及内陆湖泊水色遥感应用方面具有很大潜力。然而OHS缺乏星上定标系统，目前在轨定标采用陆地定标场的资料，其定标结果在水体等低反射率地物误差较大。因此提出一种基于传感器入瞳总辐亮度的交叉辐射定标法，该方法结合QAA（Quasi-Analytical Algorithm）准分析算法和6SV2.1辐射传输模型，利用GOCI（Geostationary Ocean Color Imager）多光谱数据对OHS高光谱数据进行交叉辐射定标。研究结果表明：①GOCI和OHS传感器获取的地物辐射相关性好，在可见光波段范围内，R²均高于0.84；②重新定标后的数据能明显改善不同传感器之间的辐射差异，在可见光波段范围内，定标误差小于9%。实验为高光谱传感器的辐射定标提供了一种新的方法，对建立高光谱定量化、业务化水色遥感处理系统，特别对OHS数据在水域的各种应用具有重要意义。

The Preliminary Study of the Radiometric Cross-calibration of Zhuhai-1/OHS

The Orbit Hyper Spectral （OHS） sensor， with high spectral and spatial resolution， is equipped on the Zhuhai-1 satellite constellation. It exhibits considerable advantages when monitoring the environment changes of coastal waters and inland lakes. However， OHS has no on-board calibration systems， the in-orbit vicarious calibration using field measurement was conducted but the result may not suitable for low reflectance target like waters. In this paper， we propose a total radiance-based cross-calibration method for OHS by using QAA （Quasi-Analytical Algorithm） marine optical model and 6SV2.1 radiative transfer model. This method makes the multiple-spectral sensor GOCI （Geostationary Ocean Color Imager） can be used for the radiometric cross-calibration of the hyperspectral sensor OHS. The result shows that the radiance observed by GOCI and OHS are highly correlated， with the R² higher than 0.84 at the visible bands. It also indicates the new calibration method can reduce the radiance differences between GOCI and OHS. The calibration errors are less than 9% at the visible bands. This study provides a new method for radiometric calibration of hyperspectral sensors and has important significance for quantitative application of hyperspectral sensors， particularly for the quantitative remote sensing of waters using OHS data.