Zhu ShuangShuang, Hong Jin, Li Zhenyang, Lei Xuefeng, Zou Peng, Liu Zhenhai, Song Maoxin
Opt Express. 2020 Apr 13;28(8):11001-11015. doi: 10.1364/OE.386566.
This work develops a method to complete the in-flight cross calibration and verification between a radiometer and an imager hosted on aircraft. The in-flight cross calibration is data transmission through time matching, space matching, and spectral matching of two polarization instruments on the same platform, and this method can not only complete the data transfer without considering the surface type to reduce the calibration cycle but also can obtain huge and rich calibration data. The radiometer is the particulate observing scanning polarimeter (POSP), which takes multi-angle, photo-polarimetric measurements in several spectral channels. The POSP measurements in the bands of 670nm and 865nm used in this work are simultaneously measured by the simultaneous imaging polarization camera (SIPC), which is on the same aircraft. The POSP is designed to provide high precision measurements of the atmospheric or earth surface radiation polarization with a substantial along-track spatial coverage, while the SIPC can provide large spatial coverage and high-resolution measurements. Through radiometer-to-imager in-flight cross calibration, the high-precision calibration coefficient of the POSP is transmitted to the SIPC, which can effectively improve the measurement accuracy of the SIPC, and realizes the remote sensing monitoring of atmospheric fine particles with large spatial coverage and high detection precision. First, we deduce the polarization models of the POSP and the SIPC, respectively, and express them in the form of Mueller matrixes, which describe the transformation from incoming polarized radiation to measured signals. Then, we deduce the in-flight cross calibration model of the POSP and the SIPC. Finally, the in-flight experiments have been carried out to validate the radiometer-to-imager in-flight cross calibration model. The results have shown the possibility to minimize the SIPC polarization degree errors with a roughly 0.01 bias relative to POSP on the land.
这项工作开发了一种方法，用于完成飞机上搭载的辐射计和成像仪之间的飞行中交叉校准和验证。飞行中交叉校准是通过同一平台上两个偏振仪器的时间匹配、空间匹配和光谱匹配来进行数据传输，这种方法不仅可以在不考虑地表类型的情况下完成数据传输以缩短校准周期，还能获得大量丰富的校准数据。辐射计是颗粒观测扫描偏振计（POSP），它在多个光谱通道进行多角度、光偏振测量。本工作中使用的670nm和865nm波段的POSP测量数据由同一架飞机上的同步成像偏振相机（SIPC）同时测量。POSP旨在提供大气或地表辐射偏振的高精度测量，具有较大的沿轨空间覆盖范围，而SIPC可以提供大空间覆盖和高分辨率测量。通过辐射计到成像仪的飞行中交叉校准，将POSP的高精度校准系数传输到SIPC，这可以有效提高SIPC的测量精度，并实现对大气细颗粒物的大空间覆盖和高检测精度的遥感监测。首先，我们分别推导了POSP和SIPC的偏振模型，并以穆勒矩阵的形式表示，穆勒矩阵描述了从入射偏振辐射到测量信号的转换。然后，我们推导了POSP和SIPC的飞行中交叉校准模型。最后，进行了飞行实验以验证辐射计到成像仪的飞行中交叉校准模型。结果表明，在陆地上相对于POSP，SIPC偏振度误差偏差约为0.01时，有可能将其降至最低。
