Yang Aixia, Zhong Bo, Wu Shanlong, Liu Qinhuo
State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China.
College of Resource and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sensors (Basel). 2017 Jan 22;17(1):204. doi: 10.3390/s17010204.
The radiometric capability of on-orbit sensors should be updated on time due to changes induced by space environmental factors and instrument aging. Some sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), have onboard calibrators, which enable real-time calibration. However, most Chinese remote sensing satellite sensors lack onboard calibrators. Their radiometric calibrations have been updated once a year based on a vicarious calibration procedure, which has affected the applications of the data. Therefore, a full evaluation of the sensors' radiometric capabilities is essential before quantitative applications can be made. In this study, a comprehensive procedure for evaluating the radiometric capability of several Chinese optical satellite sensors is proposed. In this procedure, long-term radiometric stability and radiometric accuracy are the two major indicators for radiometric evaluation. The radiometric temporal stability is analyzed by the tendency of long-term top-of-atmosphere (TOA) reflectance variation; the radiometric accuracy is determined by comparison with the TOA reflectance from MODIS after spectrally matching. Three Chinese sensors including the Charge-Coupled Device (CCD) camera onboard Huan Jing 1 satellite (HJ-1), as well as the Visible and Infrared Radiometer (VIRR) and Medium-Resolution Spectral Imager (MERSI) onboard the Feng Yun 3 satellite (FY-3) are evaluated in reflective bands based on this procedure. The results are reasonable, and thus can provide reliable reference for the sensors' application, and as such will promote the development of Chinese satellite data.
由于空间环境因素和仪器老化所引起的变化，在轨传感器的辐射测量能力应及时更新。一些传感器，如中分辨率成像光谱仪（MODIS），配备了机载校准器，能够进行实时校准。然而，大多数中国遥感卫星传感器缺乏机载校准器。它们的辐射校准基于替代校准程序每年更新一次，这影响了数据的应用。因此，在进行定量应用之前，对传感器的辐射测量能力进行全面评估至关重要。在本研究中，提出了一种评估几种中国光学卫星传感器辐射测量能力的综合程序。在此程序中，长期辐射稳定性和辐射精度是辐射评估的两个主要指标。通过长期大气层顶（TOA）反射率变化趋势分析辐射时间稳定性；通过光谱匹配后与MODIS的TOA反射率进行比较来确定辐射精度。基于此程序，对包括环境一号卫星（HJ-1）上的电荷耦合器件（CCD）相机以及风云三号卫星（FY-3）上的可见和红外辐射计（VIRR）和中分辨率光谱成像仪（MERSI）在内的三种中国传感器的反射波段进行了评估。结果是合理的，从而可为传感器的应用提供可靠参考，并将推动中国卫星数据的发展。
