【作者】 李占峰；

【导师】 王淑荣； 黄煜；

【作者基本信息】 中国科学院研究生院(长春光学精密机械与物理研究所) ， 光学工程， 2014， 博士

【摘要】 随着空间遥感技术的深入发展及遥感产品定量化应用要求的不断提高，空间遥感器的高精度定标日益显现其必要性和重要性。空间遥感器定标是遥感产品定量化的前提，遥感数据的可靠性及应用的广度和深度很大程度上取决于空间遥感器定标的准确度。所谓空间遥感器定标就是指建立遥感器输出的数字信号值与对应探测辐射量之间的定量关系。空间遥感器定标分为实验室定标和在轨定标。虽然空间遥感仪器在发射前都进行了实验室定标，但由于受卫星发射和空间环境的恶劣性以及在轨工作条件与地面定标条件不一致性的影响，其实验室定标得到仪器的性能参数会随时间发生不同程度的变化，包括突变和渐变。为了修正和标定这些变化对遥感数据精度的影响，空间遥感器需要进行在轨定标。对于高精度成像光谱仪而言，光谱定标精度及偏振特性影响直接关系到其辐射定标精度，所以本文在对国内外空间遥感器在轨定标方案的理论分析及发展研究的基础上，针对FY-3(02批)紫外高光谱臭氧探测仪的特点，主要开展了在轨光谱定标、在轨偏振修正和在轨辐射定标三个方面的研究工作。本文第一部分开展了在轨光谱定标方法研究，在总结目前常用在轨光谱定标方法的基础上，重点介绍了一种利用高分辨率参考光谱对遥感光谱仪进行在轨光谱定标的新方法。该方法根据空间遥感光谱仪狭缝函数对探测目标光谱的影响原理，将高分辨率目标光谱与仪器狭缝函数进行卷积，得到探测目标的理论光谱与实测光谱进行匹配，通过匹配误差最小确定仪器在轨光谱变化量完成在轨光谱定标。并利用该方法对FY-3B星紫外臭氧垂直探测仪进行了在轨光谱定标，通过仪器自带汞灯标准光谱检验了定标结果的精度，表明消除仪器自身影响的条件下，在轨光谱定标精度可达到±0.01nm。满足紫外高光谱臭氧探测仪的在轨光谱精度要求，验证了高精度在轨光谱定标方法的可行性。本文第二部分开展了在轨偏振修正方案研究。首先介绍了空间大气散射光谱的偏振特性并推导了空间遥感仪器的偏振响应理论，分析了偏振对空间遥感仪器测量数据的影响。介绍了两种减小偏振影响的方案：退偏器方案和在轨偏振修正方案。针对紫外高光谱臭氧探测仪特点，退偏器方案已不能满足仪器在轨偏振指标要求。因此紫外光谱臭氧探测仪采用在轨偏振修正方案。经过对在轨偏振修正的理论推导可知，进行在轨偏振修正需开展仪器偏振特性地面标定和入射光谱偏振特性在轨测量两方面工作。在仪器偏振特性地面标定方面，提出了一种较高精度的仪器偏振特性标定方法—超定方程法，并根据该方法在实验室建立了仪器偏振特性测量系统。对超定方程法和偏振测量系统的主要误差来源进行了分析并给出了修正方法。最后利用超定方法和偏振测量系统对前向临边成像光谱仪紫外样机的偏振特性进行了标定，对结果进行不确定度分析得到标定精度可达1.53%。在入射光谱偏振特性在轨测量方面，针对紫外高光谱臭氧探测仪的特性，介绍了仪器在轨偏振测量的基本方案及部分改进方案。并联合利用某项目的两台初样机模拟进行了在轨偏振测量方案验证实验，结果表明在轨偏振测量方案的精度可达2.0%。最后分析了仪器偏振特性地面标定误差和入射光谱在轨偏振测量误差对在轨偏振修正精度的影响，分析表明利用在轨偏振修正方案可将偏振对紫外高光谱臭氧探测仪测量数据影响降低到2%以内，满足仪器在轨偏振指标要求。本文最后一部分开展了在轨辐射定标研究，在分析总结国内外空间遥感仪器在轨辐射定标方法的基础上，针对紫外高光谱臭氧探测仪的特性，设计采用了”太阳+漫反板”在轨绝对辐射定标及定期月球观测的相对定标的组合方案。并详细介绍了紫外高光谱臭氧探测仪在轨辐射定标方案的具体实施及算法研究。最后对在轨辐射定标方案进行了精度分析，表明紫外高光谱臭氧探测仪在轨辐射定标不确定度为4.2%，满足仪器在轨要求。可保证紫外光谱臭氧探测仪在轨数据可靠性和精度，为后续空间遥感仪器在轨定标提供了借鉴和参考。更多还原

【Abstract】 With further development of space remote sensing and constant improvement ofrequirement on quantitative application of remote sensing data, high precisioncalibration of space-borne sensor is increasingly more necessary and important. Thecalibration is the premise of remote sensing products quantitative application.Reliability，breadth and depth of application of remote sensing data depend largely onaccuracy of calibration. The calibration is to establish a quantitative relationshipbetween the sensor output digital signal and the corresponding radiation of targets.space-borne sensor calibration includes laboratory calibration and on-orbit calibration.Although laboratory calibration were carried out before space-borne sensor’slaunching, the calibrated performance of the instrument would be certain changesover time because of the impact of harsh space environment and conditionsinconsistency between on-orbit operation and laboratory calibration. In order tocorrect and calibrate the impact,on-orbit calibration is required for space-borne sensor.For high-precision imaging spectrometer, the spectral and polarization properties aredirectly related to its radiometric calibration accuracy. So, on the basis of theoreticalanalysis and development studies on-orbit calibration of both domestic and foreignspace-based sensor, for FY-3(02) ultraviolet hyperspectral ozone spectrometer characteristics, the research on on-orbit spectral calibration, on-orbit polarizationcorrection and on-orbit radiometric calibration were carried out.The first part of this paper is about on-orbit spectral calibration. On the basis ofsummarizing the current spectral calibration methods, a new high accuracy on-orbitspectral calibration method has been introduced. According to the principles ofspectrometer slit function effect on target spectrum detection，a high resolution targetspectrum was used to convolve with instrument’s slit function. The convolved resultswere matched with corrected spectrum measured by instrument. The spectral variationwas determined by minimizing matching error, then, the on-orbit spectral calibrationwas finished. By this method, on-orbit spectral calibration of FY-3B ultraviolet ozonevertical spectrometer was made. And the result was validated by standard spectrum ofon-board mercury lamp. Under the condition of elimination the influence ofinstrument itself, the calibration accuracy could reach±0.01nm, which meet therequirements of ultraviolet hyperspectral ozone spectrometer. The feasibility thehigh-accuracy on-orbit spectral calibration was verified.The second part of this paper is about on-orbit polarization correction. Firstly,polarization properties of atmospheric scattering spectra were introduced andpolarization sensitivity of space-borne spectrometers was presented using Muellermatrix calculus. The effect of polarization on measurement data of space-bornespectrometers was analyzed. Two methods were introduced to minimize the effect,depolarizer and polarization correction. But, for ultraviolet hyperspectral ozonespectrometer, the depolarizer scheme could not meet the requirements. So,polarization correction was employed. According to the polarization correction theory,ground polarization calibration of space-borne spectrometers and on-orbit polarizationmeasurement of incident light were made to complete polarization correction. Interms of ground polarization calibration of space-borne spectrometers, a highprecision method (overdetermined equation method) was proposed. And according tothe method, a measuring system of instrument polarization characteristics wasestablished in the laboratory. The main error sources of overdetermined equationmethod and polarization measurement system were analyzed and correction method was given. Polarization properties of limb ultraviolet imaging spectrometer werecalibrated with the overdetermined equation method and polarization measurementsystem. According to uncertainty analysis, the calibration accuracy was up to1.53%.In terms of on-orbit polarization measurement of incident light, the basic scheme andsome improvement program were set for ultraviolet hyperspectral ozone spectrometer.And the related principle experiment was carried out by joint use of two earlyprototypes in XX project. The results showed that the accuracy of the polarizationmeasurement scheme could be up to2.0%. Finally, the effect of the groundpolarization errors and on-orbit polarization measurement errors on the polarizationcorrection accuracy was analyzed. It was showed that polarization effect on ultraviolethyperspectral ozone spectrometer by use of the on-orbit polarization correction wasreduced to less than2%, which meet the requirements of the instrument on-orbitpolarization index.The last part of this paper is about on-orbit radiometric calibration. On the basisof summarizing the current radiometric calibration methods, a combination calibrationplan of "sun+diffuser" absolute calibration and fixed moon’s observation relativecalibration was applied for ultraviolet hyperspectral ozone spectrometer. The specificimplementation and algorithms of the calibration plan were described. Finally, theaccuracy of on-orbit radiometric calibration scheme was analyzed, and it was showedthat the calibration uncertainty was about4.2%, which meet the on-orbit requirements.The reliability and accuracy of remote sensing data were guaranteed, and a usefulreference was provided for subsequent space-borne sensors on-orbit calibration.更多还原