卫星辐射校正场自动化观测系统的研制与定标应用

发布时间：2018-10-29 09:08

【摘要】：人工方式的场地辐射定标受到天气、资金、人力、时间等多方面的制约,定标频次有限。随着遥感卫星数量、种类的增加以及多平台遥感数据的综合应用,传统定标方法已难以满足当前遥感应用的需求。为了在保证定标精度的前提下,实现对卫星遥感器的高频次定标,本文建立了场地自动化辐射定标(Automated Radiometric Calibration in Teat-site,ARCT)技术流程和自动化定标软硬件平台,开展了对 MODIS(MODerate-resolution Imaging Spectroradiometer)的辐射定标试验。本文的主要研究工作包括以下几个方面:建立了场地自动化定标方法的基本技术流程。论文根据历史遥感数据分析了辐射定标场地表反射特性的时相变化特征,确定了场地自动化定标方法。根据辐射定标场地表反射率曲线在时相上呈小范围内近似于上下平移的特点,利用多通道场地辐射计监视地表反射率的变化,通过平移参考曲线的方式,获取实时高光谱地表反射率。利用太阳辐射计获取大气参数。结合辐射传输模型,获取卫星遥感器入瞳处的TOA(top-of-atmosphere)辐亮度,实现对过顶载荷的辐射定标。研制了场地自动化观测设备:自动化场地辐射计(Automated Test-site Radiometer,ATR)和高精度太阳辐射计(Precision Solar Radiometer,PSR),分别用于地表和大气参数的观测。为保证观测数据的稳定性与可靠性,对孔径光阑、滤光片和探测器等温度敏感的光机器件温控。为方便数据的获取,利用北斗短报文实现数据的无线长距离传输。利用"标准灯+参考板"定标系统对ATR开展了实验室定标,定标系数年变化率不大于2.5%,说明ATR的光学性能具有较高的稳定性。同时,利用太阳在参考板上形成的均匀辐亮度场对ATR现场定标,这种方式的优势在于定标与使用时光谱形状与幅值接近,避免光谱形状差异引入的不确定度。利用Langley定标法和主仪器传递定标方法对PSR开展了绝对辐射定标,定标结果偏差优于0.9%。与CE318同步观测,获取的气溶胶光学厚度偏差不大于0.02,表明PSR的测量具有较高的精度。编写了自动化定标软件,实现了从数据获取到辐射定标全链路的自动化。软件根据实测数据直接输出高光谱TOA辐亮度,可实现对任意过顶遥感器的辐射定标。对MODIS开展了场地自动化辐射定标试验。定标结果表明,ARTC能够达到人工定标的同等精度,ARCT预测的TOA辐亮度与MODIS/Aqua观测值的相对偏差的平均值在3.7%以内,与MODIS/Terra的相对偏差的平均值在5.2%以内。2016年对MODIS开展了连续4个月的场地自动化定标,其中有效定标次数为10次,将目前每年1次的定标频度提高到每月2～3次。本文在国内率先建立了场地自动化定标系统,实现了对敦煌辐射校正场地表辐射与大气参数的长期自动获取以及对遥感器的长序列自动化定标。研究结果表明,场地自动化定标技术可以在保证定标精度的前提下显著提高定标频次,降低定标成本,提高定标时效性,具有重要的应用价值。
[Abstract]:The site radiation calibration of manual mode is restricted by weather, funds, manpower and time, and the calibration frequency is limited. With the increase of the number and kinds of remote sensing satellites and the comprehensive application of multi-platform remote sensing data, the traditional calibration method is difficult to meet the needs of remote sensing applications. In order to achieve the high frequency sub-scaling of the satellite remote sensor under the premise of guaranteeing the calibration precision, this paper establishes the automatic radiometric Calibration in Teat-site (ARCT) technology flow and the automatic calibration software and hardware platform, and carries out the radiation calibration test to MODIS (MODIFY-resolution Imaging Spectroradiometer). The main research work of this paper includes the following aspects: the establishment of the basic technical process of the field automatic calibration method. According to the historical remote sensing data, the characteristics of the surface reflection of the radiation calibration field are analyzed, and the automatic calibration method of the site is determined. According to the characteristic that the surface reflectivity curve of the radiation calibration field approximates the up-and-down translation in a small range at the time of time, the change of the surface reflectivity is monitored by the multi-channel field radiometer, and real-time high-spectrum surface reflectivity is obtained by translating the reference curve. atmospheric parameters are obtained by means of a solar radiometer. Based on the radiation transmission model, the TOA (top-of-atom) radiance at the entrance pupil of the satellite remote sensor is acquired, and the radiation calibration of the over-top load is realized. Automated Test-site Radiometer (ATR) and High Precision Solar Radiometer (NOAA) are developed for the observation of surface and atmospheric parameters, respectively. In order to ensure the stability and reliability of observation data, temperature-sensitive mechanical device temperature control such as light source, filter and detector is controlled. In order to facilitate the acquisition of data, the wireless long-distance transmission of data is realized by using the Beidou short message. The calibration coefficient of ATR is not more than 2.5% by using the "Standard lamp + reference plate" scaling system, and the optical performance of ATR has higher stability. At the same time, ATR site scaling is carried out by the uniform radiance field formed on the reference plate by the sun, and the advantage of this method lies in that the spectral shape is close to the amplitude value at the time of calibration and use, and the uncertainty of the introduction of the spectral shape difference is avoided. By using the Langley scaling method and the main instrument transfer calibration method, the absolute radiation calibration was carried out. The deviation of the calibration results was better than that of 0. 9%. Compared with CE318, the obtained aerosol optical thickness deviation is not greater than 0.02, which indicates that the measuring accuracy is higher than that of CE318. Automated scaling software has been developed to automate the acquisition of data from data to the full link of radiation calibration. The software directly outputs the high spectral TOA radiance according to the measured data, and the radiation calibration of any overtop remote sensing device can be realized. The field automatic radiation calibration test was carried out on MODIS. The calibration results show that ARTC can achieve the equivalent accuracy of artificial target, the mean value of the relative deviation between the TOA radiance and MODIS/ Aqua observed by ARCT is within 3. 7%, and the mean value of relative deviation from MODIS/ T10A is within 5. 2%. In 2016, a continuous four-month field automatic calibration is carried out for MODIS. wherein the effective scaling times are 10 times, and the scaling frequency of the current one time is increased to 2 to 3 times per month. In this paper, a field automatic calibration system is established in China, which realizes the long-term automatic acquisition of surface radiation and atmospheric parameters of Dunhuang radiation correction field and the automatic calibration of long sequence of remote sensors. The research results show that the field automatic calibration technology can significantly improve the calibration frequency on the premise of guaranteeing the calibration precision, reduce the scaling cost, improve the calibration efficiency and have important application value.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V443.5

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