【作者】 徐丽华；

【导师】 李先华；

【作者基本信息】 华东师范大学 ， 地图学与地理信息系统， 2005， 博士

【摘要】 作为对地探测的遥感技术所获取的遥感数据包含地面和大气信息,并且主要是地面信息。如何将遥感数字图像中弱的大气信息与强的地面目标信息分离,这一问题制约着大气遥感和大气环境质量研究与监测定量化水平的进一步发展。为解决这一问题,国内外遥感专家付出了不懈的努力,取得了一些进展。但是迄今为止,所有这些方法基本上无一例外的都是条件苛刻的近似解,尚未从根本解决。李先华教授在长期从事相关研究的基础上,提出利用地面反射率进行大气程辐射逐点反演计算,生成大气程辐射遥感数字图像的解决方案,并完成其原理方法研究。本文正是根据这一原理方法,在生成地面反射率图的基础上,实现了大气程辐射遥感影像的计算机生成,并分别以ETM+和MODIS数据为例,分析了上海市大气环境质量的时空格局特征及其影响因素,最后以大气污染地面观测数据(PM10浓度)为基准,对大气环境质量进行了评价。 根据大气程辐射反演的原理,获取准确的地面反射率是问题的关键,这也是本论文的核心。地面反射率与行星反射率之间存在复杂的非线性关系,利用模糊神经网络来模拟这种非线性关系。选择实测典型地物中反射率随时间变化较小的地物类型,以其反射率值作为网络的学习样本,对网络进行训练,然后将行星反射率、6S大气校正后的反射率以及按光谱特征分类数据输入到训练后的网络进行模拟,仿真输出地面反射率。以上是ETM+地面反射率生成方法.对于MODIS的地面反射率计算则主要是依赖于6S的反射率校正结果,是对连续的校正结果进行曲线拟合,获得每个像元对应的大气状况最好条件下的反射率校正值,生成MODIS地面反射率图。 大气程辐射遥感影像表征了大气质量状况,根据上述原理和方法,生成了上海市ETM+和MODIS的大气程辐射遥感影像。由于二者分别具有较高的空间和时间分辨率,因此分别用来反映上海市大气污染状况的空间格局和时间变化特征。结果显示,城市和农村的大气环境质量对比还是比较鲜明。但是在城市内部大气环境质量的空间变化程度要远远高于农村内部的变化,这与城市内部复杂的下垫面性质和人类活动息息相关。就时间变化来看,最主要的特征是,变化比较剧烈,受风向、风速和外来污染源影响较大。进一步对这种时空格局的影响因素分析揭示,城市下垫面性质是最主要的影响因子之一,城市内部的绿地公园、大型水面对大气污染具有显著改善作用;而工业生产的影响则具有显著的差异,老工业区,以重工业、化学工业等为主的工业区对大气污染具有很大贡献,而以电子等新兴高科技工业为主的工业区则对大气污染几乎没有影响;人口密度与大气污染程度关系比较复杂。对不同时间上海市大气环境质量进行评价,结果揭示上海市总体上大气环境质量较好,但由于自然因素和人为因素的影响,时间差异较大。 由此可见,利用完全不含地面信息、表征大气环境质量的大气程辐射遥感影像进行大气环境质量分析,更能科学、定量地探测出传统研究方法所不能揭示的空间和时间上的细节特征,研究结果准确,并有很高的推广和应用价值。更多还原

【Abstract】 As exploration to ground objects, data received by Remote Sensing techology include ground information and air information. How separate weak air parts from strong ground parts, the problem has restrict the more devlopment of quantitative levels in that research the air remote sensing and the air environmental quality and monitor them. For resolving the problem, muti- experts of RS’s fields has made a little progress, by remorselessly making great efforts. For example, famous Split Window’s Retrieving is the successful method. But the methods have not radically resolve the problems, for its the approximate correct answers in rigorous conditions. Professor Li XiHua put forward the complete resolved method that retrieves air path radiation calcauted by surface reflectivity point by point. And he had researched the principle and methods.In the paper, the map of reflectivity firstly has done using by the Li’s methods, then, the image of atmospheric path radiation is calculated using by computer. As ETM+ and MODIS for example, the character and influenced factors of spatial and temporal pattern are analysed in ShangHai. Lastly, based on density of PM10, the quality of air environment is evaluated.The key method is that accurately retrieve the ground reflectivityin the paper. Fuzzy neural networks (FNNs) can simulate the non-linear relation that the ground reflectivity and the planet reflectivity. The training samples of FNNs are the reflectivity obtained by measuring objects surface out of the Lab. The input nerve cells are the planet reflectivities, air corrected reflectivities using by 6S models, and the classified types on the spectral character. The simulated results are the reflectivities of ground objects. So, the ETM+ map of ground reflectivity has simulated by computer. The MODIS reflectivity is almostly obtained from air corrected reflectivities using by 6S models. Then, the image of atmospheric path radiation is possibly calculated by Li’s methods.The image of atmospheric path radiation represents the air quality. So, the air quality can be analyzed, as the image of atmospheric path radiation for the objects of research. The spatial pattern of air quality can be analyzed by ETM+ image of atmospheric path radiation, for the resolution of ETM+ image is 30 meter. While the temporal pattern of air quality can be analyzed by MODIS image of atmospheric path radiation, for its resolution is 250 meter or 500 meter. The spatial pattern is that the discrepancy between urban and rural is obviously. The spatial variation inner the urban is far more obviously than inner the rural. The pattern is caused by the complicated ground types inner the urban and the human being activities. The temporal pattern is that the variety of air qualities is very intense, and the rule is hardly found.更多还原