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我国热红外传感器在轨辐射定标主要通过基于大面积均匀目标的实测数据开展的单点法场地定标以及与高精度中分辨率载荷的多点法交叉定标来实现.单点法场地定标耗时、费力,且无法计算定标系数的截距,与中分辨率载荷的多点法交叉定标受到入瞳辐亮度匹配算法的制约,两者都影响着我国在轨定标系数精度的提高.利用AIRS高光谱数据的光谱特征,针对国产HJ-1B卫星热红外通道进行多点交叉定标方法研究,通过选择临近成像时间、选择均匀区域消除时空差异,同时通过MODTRAN辐射传输模型开展逐像元计算,对不同像元间的观测几何因素进行归一化处理.通过基于单一均匀区域、不同时相的时间序列多点法和基于同一时相、不同均匀区域的均匀目标多点法交叉定标获得HJ-1B热红外通道定标系数,并以基于HJ-1B热红外通道查找表法获取的星上定标系数为基准,对多点法交叉定标所得定标系数进行验证.经过分析,通过剔除时间序列多点法中的异常点和调整均匀目标多点法中的匹配因子,所得定标系数模拟得到的等效离水亮温值与基于星上定标系数反演得到的离水亮温值偏差分别达到1.81和0.92 K.由结果可知,基于AIRS的HJ-1B热红外通道的均匀目标多点法交叉定标结果更精确可信.
China’s thermal infrared sensor in-orbit radiation calibration mainly through large-scale uniform target measurement data to carry out single-point method of calibration and resolution of medium-resolution high-resolution multi-point cross-calibration method to achieve. It is difficult to calculate the intercept of the calibration coefficient with the time-consuming and costly, and the multi-point cross-calibration of the medium-resolution load is constrained by the pupil radiance matching algorithm, both of which affect the accuracy of the in-orbit calibration coefficient The multi-point cross-calibration method for domestically produced HJ-1B satellite thermal infrared channels was studied by using the spectral features of AIRS hyperspectral data. By selecting the adjacent imaging time and selecting uniform regions, the space-time differences were eliminated. At the same time, MODTRAN radiation transmission model By pixel-by-pixel calculation, the observed geometric factors of different pixels are normalized.Through the multi-point time-series method based on a single uniform region, different time phases and the uniform target multi-point method based on the same time phase and different uniform regions Cross calibration to obtain HJ-1B thermal infrared channel calibration coefficient, and based on the HJ-1B thermal infrared channel lookup table to obtain the on-board calibration coefficient for multi-point Cross-calibration of the calibration coefficient to be validated.After analysis, by eliminating the abnormal points in the time series multi-point method and adjusting the matching factor in the uniform target multi-point method, the resulting calibration coefficient simulated equivalent water temperature And the deviation from the water temperature value based on the on-board calibration coefficients are 1.81 and 0.92 K. The results show that the HJ-1B thermal infrared channel based on AIRS cross-calibration results of uniform target multi-point method is more accurate letter.