空间外差遥感数据光谱-干涉图双向校正算法研究

Research on Spectral Interferogram Bidirectional Correction Method for Spatial Heterodyne Remote Sensing Data

空间外差光谱技术(SHS)作为新型高光谱分析技术,被广泛应用于大气检测、卫星遥感等领域,但由于空间外差光谱仪的制作不理想或工作环境的变化都会改变仪器参数而引入误差,使干涉图数据不准确,需要进行误差校正。在卫星平台下,由于与地面环境的巨大差异,导致地面测定的校正参数对空间外差干涉图数据不再适用,特别是调制项误差(相位误差和非均匀误差)的改变,极大影响了光谱的准确性。针对空间外差遥感数据的调制项误差,从光谱与干涉图两个方面入手,进行误差分离与原因分析,认为空间外差遥感数据误差主要来源于CCD尺寸伸缩导致的光谱频率变化和CCD响应改变导致的干涉图强度变化,提出了光谱-干涉图双向校正方法。校正测试数据选取高分五号搭载检测仪(GMI)实测的12条O 2吸收光谱。取其中一条作为标定光谱,以SCIATRAN仿真的无误差光谱为基准,与标定光谱进行对比,分析两者在光谱维的频率偏差,通过特征峰频率确定两者的频率变换关系。然后根据变换关系将仿真光谱进行频率拉伸,使拉伸后的仿真光谱与实测光谱谱峰重合,计算拉伸仿真光谱与实测光谱干涉图,将两者干涉图相比得到干涉图强度的变化关系。最后将干涉图强度变化关系用于其余11条光谱的校正,得到校正后光谱。为了衡量校正效果,以校正前后光谱的标准差、均方误差和信噪比作为评价指标。结果显示标准差、均方误差都明显降低,同时信噪比显著增大,且标准差基本都在0.07以下,信噪比基本能达到20以上。其中校正效果最好的实测光谱,标准差减少了0.3767,信噪比提高了25.1016,均方误差降低了0.1587,校正效果较差的实测光谱,标准差减少了0.2296,信噪比提高了9.6328,均方误差降低了0.1049。因此所提出的光谱-干涉图双向校正方法对空间外差遥感数据的误差校正起到较好的效果,且处理过程简单,为同类数据的处理提供了一种新思路。

Spatial Heterodyne Spectroscopy(SHS),a new hyperspectral analysis technology,has been widely used in atmospheric detection,satellite remote sensing and other fields.However,because the fabrication of spatial heterodyne spectroscopy is not ideal or the change of working environment will change the instrument parameters and introduce errors,the interferogram data is not accurate,so error correction is needed.Due to the huge difference between the satellite platform and the ground environment,the correction parameters measured on the ground are no longer applicable to the spatial heterodyne interferogram data,especially the change of modulation errors(phase errors and non-uniform errors),which greatly affects the accuracy of the spectrum.Based on spatial heterodyne modulation of the remote sensing data error,from two aspects of spectrum and the interference figure,separation and analysis of the causes of error,think mainly comes from the CCD size scale spatial heterodyne remote sensing data error caused by spectral frequency change and the CCD response to a change in intensity of interference pattern change,spectral interferogram bidirectional correction method is proposed.Twelve O 2 absorption spectra measured by the Greenhouse Gases Monitoring Instrument(GMI)on GF-5 were selected for calibration.Onewas taken as the calibration spectrum,and the error-free spectrum simulated by SCIATRAN was compared with the calibration spectrum.The frequency deviation of the two spectra in the spectral dimension was analyzed,and the frequency of the characteristic peak determined the frequency transformation relationship between the two.Then,the simulated spectrum is stretched in frequency according to the transformation relationship so that the simulated spectrum after stretching coincides with the measured spectrum peak.The interferogram of the stretching simulation spectrum and the measured spectrum is calculated,and the changing relationship of the interferogram intensity is obtained by comparing the interferogram of the two.Finally,the intensity variation relation of the interferogram is used to correct the other 11 spectra,and the corrected spectra are obtained.To measure the correction effect,The standard deviation(STD),mean square error(MSE)and signal-to-noise ratio(SNR)of the corrected spectra were calculated;results show that both STD and MSE were significantly lower,with a significant increase in SNR,the basic and STD are below 0.07,the SNR can reach more than 20.The STD of the spectrum with the best correction effect decreased by 0.3767,SNR increased by 25.1016,and MSE decreased by 0.1587.The STD of the spectrum with poor correction effect decreased by 0.2296,SNR increased by 9.6328,and MSE decreased by 0.1049.To sum up,it shows that the spectral interferogram bidirectional correction method proposed in this paper has a good effect on error correction of spatial heterodyne remote sensing data,and the processing process is simple,providing a new direction for similar data processing.