中国科学院遥感与数字地球研究所-高光谱遥感应用技术研究室推荐内容
【2007博】基于MODIS与太阳光度计联合遥感太湖地区大气特性
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【作者】 胡方超 【导师】 童庆禧；张兵；郑兰芬 【 学位年度 】 2007 【论文级别】 博士 【关键词】 高光谱遥感，气溶胶光学厚度，水汽总量，MODIS，CE318 【Key words】 Hyperspectral Remote Sensing; Aerosol Optical Depth, Water Vapor Amount, MODIS, CE318 【中文摘要】 近年来，我国大气污染严重，空气质量恶劣，开展对大气特性研究的需求十分迫切。遥感作为一种新的技术手段具有很大优势。 本文以太湖为研究区，通过水面光谱实验采集，地基太阳光度计大气测量，和当天的MODIS遥感影像，联合遥感太湖地区的大气特性，其中对大气的水汽总量和气溶胶光学厚度做了重点研究。本文的研究成果如下： 1）提出了一种利用太阳光度计直射数据反演气溶胶光学厚度的改进算法。考虑了影响气溶胶光学厚度反演误差的各种因素，其中对大气光学质量，Rayleigh光学厚度，臭氧的吸收系数等因素做了改进，特别是计算Rayleigh标准光学厚度积分式时考虑了复折射指数，退极化因子。结果表明该算法能提高反演的精度。 2）提出了一种新的太阳光度计定标方法。研究比较了太阳光度计直射通道的各种定标技术，并应用于实际的实验测量中。除了Langley法，标准传递法外，并在理论上提出了一种新的定标方法。 3）光度计和MODIS联合反演大气水汽总量。确定了光度计用改进Langley法中的瞬态法，和MODIS的近红外两波段比值法效果较好，最后获得逐像元的水汽总量。 4）提出了一种实验确定气溶胶类型的方法。通过与卫星影像准同步的地面光谱和太阳光度计实验，利用辐射传输模式6S，变化气溶胶类型各组分，建立关于星上辐射的查找表，并利用新定义的相对误差参量，在其总误差最小时确定气溶胶类型。 5）实现、改进并扩展计算单球粒子的Mie散射程序。可以计算多分散体系的大气气溶胶粒子群并包括偏振的光学特性，并用于实际太湖地区大气气溶胶偏振散射相函数等光学特性的计算中。 本文的研究成果可为大气校正和水色遥感奠定基础。
【Abstract】 Recently, the atmospheric pollution and awful air have threaten our nation, therefore it cries for the study the atmospheric properties. As a new technology, remote sensing has a lot of advantages. The paper selected Lake Taihu as our study area. By collecting the spectrum of the water surface, measuring of atmosphere using the sunphotometer, and acquiring the image of the MODIS on the same day, the data were used to get properties of atmosphere. The key point of the study is related to the atmosphere water vapor amount and the aerosol optical depth (AOD). The research results in this paper are presented as following: 1) Propose an improved algorithm for the retrieval of aerosol optical depth using the direct sunlight data of sunphotometer. Different effects on the inversion errors of AOD are mainly analyzed and improved algorithms have been used to get high inversion precision of aerosol optical depth, respectively in the air mass, Rayleigh optical depth, and ozone absorption coefficient etc.Especially in the computation of standard Rayleigh optical depth using the integral form, not only the effects of complex refractive index but also the depolarization ratio. The computed results have been showed that this algorithm can improve the accuracy of the retrieval. 2) A new calibrated method is presented .The different techniques of calibration for the channels of the direct sunlight are compared and applied in the actual measurements. Except of the Langley method and the standard translated one, a new calibrated one is presented in the theory. 3) As the atmosphere water vapor amount is inverted using the sunphotometer and MODIS data. The good effects are shown in the instant method of the Langley and the ratio of reflectance for two bands and the water vapor amount of every image pixel are obtained. 4) A method based on measurements for determining the aerosol type is announced. By using the nearly synchronous measurements of the data from surface spectrum and the sunphotometer with the image, and by use of the radiative transfer model 6S, varying the components of the aerosol type, a LUT (look up table) is made for the radiance on the satellite. When the total relative error of the new defined parameter for relative error is getting to the least, the aerosol type will be decided. 5)The Mie code which was used to calculate the single sphere particle has been improved, extended and realized to compute the optical characteristics including polarization of the poly –disperse aerosols. And it has been used to get the polarized phase function of aerosols over Lake Taihu. The results of this study will be provided for the supporting of the atmospheric corrections and the water color remote sensing.
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