Knowledge Resource Center for Ecological Environment in Arid Area
| 罗布泊典型环境敏感因子探测与盐壳演化 过程推演 | |
| 其他题名 | Typical Environmentally Sensitive Factors Detection and Salt Crust Evolution Processes Extrapolation in Lop Nur Lake Basin Area |
| 刘长安 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 邵芸 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 罗布泊作为全球干旱性气候的代表地区，对气候变化高度敏感。历史上罗布泊曾经烟波浩渺，物产丰富，孕育了著名的沙漠绿洲文明。时至今日，罗布泊已完全干涸，遥感影像上仅留下如同人耳的环状圈层纹理，忠实记录着湖泊过往的演化历史，其中蕴含着丰富的第四纪地质和古气候等信息，对研究全球气候变化具有重要意义。以往的雷达遥感技术大多应用在地物结构识别、土壤水分反演、植被层参数估计等方面，本文主要阐述雷达遥感在干旱/半干旱区域的应用。本文综合利用多源遥感数据，特别是全极化SAR数据，运用遥感地学分析手段，对罗布泊湖盆地区进行深入分析。着重研究罗布泊湖盆地表和次地表层参数的提取，综合利用基于三维建模的电磁散射数值仿真、基于近景摄影测量理论的粗糙度测量方法和极化SAR等多种类型的遥感探测手段，结合野外地面考察和实验室测量的数据，进行定性分析和定量模拟。同时寻找其中与环境变化相关联的关键因子，发展基于SAR数据建立的罗布泊区域气候演变规律分析方法，重点探讨罗布泊耳纹的形成机制，并对罗布泊湖盆区域环状纹理特征的气候环境意义进行探讨。尝试建立地形地貌等气候环境指标与遥感参数之间的定量关系，力求大致还原罗布泊在千年尺度上的干涸时间序列和过程。这对于明确全球气候变化在罗布泊的区域表现，研究历史时期全球变化对干旱区生态环境与人类生存条件的影响机制均具有重要的参考价值。本研究中笔者的研究成果和创新性贡献为：1) 研究了罗布泊地区某一粗糙度参数下的三维随机粗糙表面的生成原理和相关方法；基于MoM电磁计算方法，利用FEKO电磁散射软件进行数值模拟，深入论证了罗布泊湖盆区域的雷达穿透特性。2) 基于同极化相位差的次地表介质层厚度的反演方法，针对罗布泊古湖盆区域复杂而特殊的散射机理，利用雷达遥感技术定量化地获取了地下含水层深度在罗布泊古湖盆区域的整体分布规律。分析了浅地表含水层埋深在罗布泊古湖盆区域从湖岸到湖心的整体分布规律和相关的特征，并结合盐壳生长的地貌动力学模型和水面风应力模型探讨了其中所蕴含的气候环境意义。3) 基于地表微地貌结构的近景摄影测量三维重建理论，提出了一种新的高精度的多尺度粗糙度测量方法。为更好的描述盐壳地表的微地貌形态，提出了一个可以很好的结合地表均方根高度和相关长度物理意义的一个新参数Sl。在此基础上基于SERD的地表的粗糙度反演理论，进行了针对罗布泊古湖盆区域具有较大粗糙程度的不同形态的盐壳的识别和划分实验。结合盐壳生长演化的地貌动力学模型对所得到的反演结果进行了气候环境意义上的推演。 |
| 英文摘要 | Lop Nur, as a representative area of global drought climate, is highly sensitive to climate change. In the past, Lop Nur was abundant in resources, giving birth to the famous desert oasis civilization. Today, Lop Nur has completely dried, only leaving ear-like circle texture in remote sensing images, which recorded the evolutionary history of the lake in the past. Containing rich quaternary geology and climate information, it is of great significance for the study of global climate change.Most of the previous radar remote sensing technologys are focused in the fields of structural identification、soil moisture retrieval and vegetation layer parameters estimation. This paper mainly expounds the application of radar remote sensing in the arid/semi-arid regions. Using multi-source remote sensing data, especially full polarimetric SAR data, and remote sensing geoscience analysis, this paper carries a thorough analysis of the Lop Nur Lake Basin area. Based on the numerical simulation of electromagnetic scattering, close range photogrammetry theory and Polarimetric SAR technology, combined with field investigations and laboratory measurement data, this paper focuses on the extraction of Lop Nur Lake surface and subsurface layer parameters. While looking for key factors associated with the environmental change, the paper established the climate evolvement analysis method of Lop Nur region based on SAR data, studied the formation mechanism of the ear-like texture and its climatic and environmental significance. The paper tries to establish the quantitative relationships between topography/climate environment indexs and radar remote sensing parameters in order to roughly restore the whole dry processes of Lop Nur Lake in the history. It is of great significance to clarify the influences of global climate changes on Lop Nur region, and to study the impacts of global changes on the ecological environment and human living conditions in arid/ semi-arid areas.In this study, the author's research results and innovative contributions include:1) Studied principles and related methods of the generation of three-dimensional random rough surface, generated an equivalent face in the sense of radar scattering in Lop Nur lake region, and combined with the FEKO software, provided preliminary demonstration of radar penetration characteristics in the Lop Nur Lake region.2) The depth of a subsurface brine layer is retrieved in Lop Nur by co-polarized phase difference of surface scattering. Based on field investigation and analysis of sample properties, a two-layer scattering structure was proposed with detailed explanations of scattering mechanisms. The co-polarized phase difference of surface scattering was extracted by model-based polarimetric decomposition method. According to the retrieved maps, some interesting phenomena were found, and several hypotheses about the past water withdrawal process and the environmental evolution had been proposed to theoretically explain these phenomena.3) Based on the close range photogrammetry theory, we proposed a three dimensional (3D) micro-topography reconstruction method to measure surface roughness in a multi-scale way. In order to describe the micro topography of the surface of the salt crusts, a new parameter Sl which can combine the physical meaning of the surface root mean square height S and correlation length L is put forwarded. The physical meaning of the PolSAR parameter Single Bounce Eigenvalue Relative Difference (SERD) is reinterpreted and it is used to retrieve parameter .The different forms of salt crust in Lop Nur lake basin area are identified and classificed. Furthermore, the distributions of different salt crusts in the certain lake area were analyzed. Based on hypotheses of the evolution of surface salt crust and the drying-up cycle of lakes, the fluctuation processes of an ancient lake in Lop Nur were discussed theoretically. These can help to have a better understanding of environmental changes in arid and semi-arid regions. |
| 中文关键词 | 罗布泊 ; 极化SAR ; 参数反演 ; 浅地表含水层 ; 盐壳 ; 环境变化 |
| 英文关键词 | Lop Nur Polarimetric SAR Parameter inversion Subsurface aquifers Salt crusts Environmental change |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 地图学与地理信息系统 |
| 来源机构 | 中国科学院遥感与数字地球研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287810 |
| 推荐引用方式 GB/T 7714 | 刘长安. 罗布泊典型环境敏感因子探测与盐壳演化 过程推演[D]. 中国科学院大学,2016. |
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