Knowledge Resource Center for Ecological Environment in Arid Area
| 集成光学与微波遥感苏打盐碱地水盐含量反演方法研究 | |
| 其他题名 | The Reversal Method Study to Moisture Content and Salinity of Soda Saline-alkaline Soil by Integrating Optics and Microwave \t Remote Sensing |
| 李洋洋 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 赵凯 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 土壤盐碱化是世界上面临的一个严重问题，它严重影响干旱、半干旱区域的生态及农业可持续发展。我国吉林省西部地区属于世界三大苏打盐碱地之一，土地盐碱化使得该地区生态平衡受到严重影响。利用遥感技术快速、准确地监测盐碱化变化过程，对合理开发利用盐碱地具有重要意义。 \n 中国科学院东北地理与农业生态研究所大安碱地生态试验站长期在吉林省西部地区开展苏打盐碱地的改良研究，结果表明不同碱化特性的盐碱地生长着不同的植被类型，当盐碱化程度较高时，无植被生长。利用光学遥感技术能够有效地监测植被生长区和裸露盐碱地，但是对植被高度、长势等无法进行有效的监测，因此不能对盐碱地特性进行更加细致的识别，尤其是水盐含量变化的监测。含盐土壤在一定含水量的条件下，具有较好的导电特性，使微波后向散射、微波辐射特性对其介电常数具有较强的敏感性，使应用微波遥感监测盐碱土壤具有可行性。然而，微波遥感信息常常受植被或地表粗糙度等因素影响，增加了盐碱地特性识别的复杂性和不确定性。 \n 论文在中国科学院重要方向性项目“土壤湿度与积雪参量高精度微波遥感反演机理研究”的支持下，依托中国科学院长春净月潭遥感实验站和大安碱地生态试验站，通过有效选取研究实验区，以Landsat 8、RADARSAT-2 C波段全极化SLC影像为信息源，在星地同步观测实验的基础上，开展了吉林省西部地区苏打盐碱地水盐特性反演方法的研究。主要研究成果如下： \n 利用合成孔径雷达（SAR）极化目标分解理论，提取了研究区盐渍土的微波遥感后向散射信息特征，有效地应用于轻度盐碱地的识别，提高了相应的识别水平。 \n 通过SAR极化目标分解，利用Cloude-Pottier分解散射熵值的变化，论述了盐碱地的散射随机性，其熵值高于农田和水体。由此表明，当雷达足印大于15m时，通过建立雷达后向散射系数与盐碱土介电常数之间的确定性函数关系，开展盐碱地特性微波遥感的监测是不可行的。 \n 利用盐碱地Freeman-Durden分解的三种散射机制的变异系数（标准差与均值比值）较大的特征，表述了盐碱地具有相对较高的散射离散度，主要体现在25*25像元范围四极化后向散射统计中遥感信息变化范围较大。同时，也阐明了草地植被覆盖的随机性、草地植被长势随机性、盐碱地地表含盐量的随机性、叶片方向随机性等构成的混合像元是影响雷达后向散射系数随机特性的重要因素。 \n 根据盐碱土介电常数对频率响应差异，利用双频地基微波辐射计亮度温度观测数据，应用Levernberg-Marquardt算法，实现了土壤介电常数（实部和虚部）及地表均方根高度三参数的同时反演。 \n 应用全极化雷达数据和NDVI建立了含水量、含盐量反演的经验公式，其中含水量反演均方根误差为3.169%（体积含水量），含盐量反演误差为3.175g/Kg。 \n 提出了基于理论知识和模拟数据库，进行盐碱土壤水盐含量半经验模型的方案，并进行了初步实现。首先，利用AIEM模型建立模拟数据库，通过各参数敏感性分析，建立了组合粗糙度、介电常数幅值与HH、VV极化后向散射系数的关系式，再然后结合水云模型，去除植被影响，反演得到地表组合粗糙度值及介电常数幅值。 \n 论文的研究工作为开展盐碱地特性遥感监测提供了新的途径和方法，为国家自然科学基金面上项目“集成光学与微波遥感苏打盐碱地水盐含量的反演方法研究”的立项与研究奠定了基础。 |
| 英文摘要 | Soil salinization is one of the serious problems in the world which effects the eco-environment and sustainable agricultural development in arid and semi-arid areas. Western Jilin province is one of the three major regions of soda salt-alkalinized soil in the world, and the soil salinization severely affects the ecological balance of the region. Using remote sensing technology to rapidly and accurately monitor the change process of soil salinization has great significance on the reasonable exploitation and utilization of saline-alkali land. \n Da’an sodic land experiment station of Northeast institute of geography and agroecology,Chinese academy of sciences carry out the research of soda alkali-saline land improvement for a long time, and studies show that soil with different alkaline properties grown with different vegetation types, in addition, when the salinization degree is high, there is no vegetation growth on. The optical remote sensing technology can effectively monitor bare saline-alkali land and vegetation cover land while unable to monitor the plant height and vegetation growth effectively which can not identify the saline-alkali land meticulously, especially the monitoring of water and salt content change. Salinized soil with a certain water content have superior electrical conductivity which result to strong sensitivity between its dielectric constant and the characteristics of microwave backscattering and radiation, further more, the the application of microwave remote sensing monitoring of salinized soil is feasible. However, signal of microwave remote sensing is often affected by factors such as vegetation and surface roughness which increases the complexity and uncertainty of saline-alkali land feature recognition. \n This paper is carried out under the supported of the Innovation Program of Chinese Academy of Sciences“the mechanism research on soil moisture and snow parameter high-precision inversion from passive microwave remote sensing (KZCX2-YW-340)” and also JingYue remote sensing experiment station and Da’an sodic land experiment station. Through effective selection of research area, and the Landsat8 OLI and RADARSAT-2 C band full polarization SLC image as the data source and at the same time on the basis of ground-based and satellite-based synchronous observation experiment, the water and salt content inversion method study of soda alkali-saline land in Western Jilin province were carried out. The main research results in the following aspects: \n (1) Based on the SAR polarization decomposition theory, the microwave remote sensing backscattering characteristics of saline-alkali land were extracted in the study area which can effectively identify the mild saline-alkali land and improve the accuracy of identification of saline-alkali soil. \n (2)Using the scattering entropy parameter derived by Cloude-Pottier decomposition, this paper discusses the scattering random characters of saline-alkali soil. The scattering entropy of saline-alkali soil is higher than cropland and water body which means that the scattering of saline-alkali soil is arbitrary distribution. The high scattering entropy suggested that it is infeasible to carry out monitoring of saline-alkali soil by microwave remote sensing through establishing deterministic function relationship of radar scattering coefficient and dielectric constant of saline-alkali soil. \n (3)Using the variation coefficient (ratio of standard deviation and mean value) of three scattering mechanism parameters derived by Freeman-Durden decomposition, this paper shows that the saline-alkali soil has a relatively high discrete degree, which presents the large variable ranges of full polarization statistical information with 25*25 pixels. At the same time, this paper also illuminates that the saline-alkali soil is a mixed pixel with the randomness of grassland cover, the randomness of grassland growth,the randomness of salinity content, and the the randomness of blade direction ,all of which result to the scattering randomness of a radar backscattering echo. \n (4)According to the frequency response difference of saline-alkali soil dielectric constant, the three parameters soil complex dielectric constant (real and imaginary part) and surface root-mean-square hight are simultaneously retrieved by Levernberg- Marquardt algorithm from dual-frequency ground-based microwave brightness temperature observation data. \n (5)Combined full polarization radar and NDVI data, the experience retrieval formula of salt and water content was established, and the results RMSE of water content is 3.169% and the RMSE of salt content is 3.175g/Kg. \n (6)The semi-empirical retrieval program of saline-alkali soil water and salt content were proposed based on theoretical knowledge and simulation database, and has carried on the preliminary implementation.First of all, establish the simulation database by using AIEM model, and then through the parameter sensitivity analysis, the relationship between combined roughness, complex dielectric constant and HH\\VV backscattering coefficient were proposed. Secondly, combined with water-cloud model, the vegetation effect was removal. At last, the dielectric constant amplitude and combined roughness were simultaneously inversed. \n Thesis research work provides a new way for monitoring the characteristics of saline-alkali land by remote sensing technique.Further more, this work laid a foundation for the project approval and research of the national natural science foundation item “The Reversal Method Study to Moisture Content and Salinity of Soda Saline-alkaline Soil by Integrating Optics and Microwave Remote Sensing”. |
| 中文关键词 | AIEM模型 ; 微波遥感 ; 土壤含盐量 ; RADARSAT-2 ; 极化分解 ; 苏打盐碱地 |
| 英文关键词 | AIEM Model Microwave Remote Sensing Soil Salinity RADARSAT-2 Polarization Decomposition Soda Saline-alkali Soil |
| 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 | 中国科学院东北地理与农业生态研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287373 |
| 推荐引用方式 GB/T 7714 | 李洋洋. 集成光学与微波遥感苏打盐碱地水盐含量反演方法研究[D]. 中国科学院大学,2014. |
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