Knowledge Resource Center for Ecological Environment in Arid Area
| 罗布泊地区高精度DEM建立及历史风力强度重建 | |
| 其他题名 | Reconstruction of High Precision DEM and Historical Wind Strength in Lop Nur Region |
| 谢凯鑫 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 邵芸 ; 宫华泽 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 作为中国西部乃至全球典型极端干旱区之一，罗布泊地区对气候变化极其敏感。历史时期，罗布泊曾经烟波浩渺，物产丰美，与今日完全干涸的湖床形成了鲜明对比，其留下的细致纹理圈层忠实地记录了这一变迁过程，是大自然留下的宝贵资源，其中蕴含着丰富的古气候和第四纪地质等信息，对研究干旱区环境演变规律以及全球气候变化具有重要意义。罗布泊地形是研究罗布泊干涸过程以及环境演化的基础，具有非常重要的研究价值。高精度的地形数据，结合罗布泊的环状纹理特征，将为还原罗布泊干涸过程提供重要的基础资料。但是由于罗布泊地区地势平坦，高差很小，现有的地形资料，包括InSAR及立体摄影测量等手段获取的地形数据，精度为十数米，难以满足要求，激光高度计数据，虽然精度很高，但获取的是剖面的点状数据，而实地测量结果数据量有限且相互矛盾，因此，对罗布泊地区的地形特征一直未有一个连续的宏观大尺度上的精确认识。本文首次将TerraSAR-X/TanDEM-X(TSX/TDX)双星系统干涉数据应用于罗布泊地区地形研究。运用TSX/TDX短基线数据，通过InSAR技术建立了罗布泊地区高精度的DEM，并利用激光高度计GLAS数据完成了对DEM的高程校正和精度评价，高程精度达到37.6 cm。根据建立的DEM，可以清晰的看出湖盆闭合的环状纹理、西部河网、带状洼地、楼兰和临海古城等地形特征，确定大罗布泊区范围内，地势较为平坦，湖盆环状纹理区高程值最低（785-790米），相邻环纹间的高差不超过1米，总高程差不超过5米，呈现出四周高，中间低，由外到内高程递减的特征，未发现有湖心岛存在。利用建立的高精度DEM，重点讨论了罗布泊环状纹理区的高程变化特征，研究发现罗布泊环状纹理区呈现北部大致水平、南部高程逐渐增大的特征，南北最大高差超过1米，且选取的4条典型的环状纹理均呈现此规律，验证了“同环不同高”现象，确定了其确实是罗布泊环状纹理区地形特征的真实表现。根据罗布泊环状纹理的“同环不同高”现象，以及风应力机制和湖流模型，本文将湖盆环状纹理在盛行风上风向与下风向之间的高程差异与风力强度联系起来，通过误差分析，确定可以用该高程差来代表主风力强度。本文将筛选后的高程差作为历史风力强度的替代性指标，不同的环状纹理代表不同的历史时期，形成历史风力强度曲线，最后用湖流模型进行数值模拟，再现了罗布泊在逐渐干涸过程中的风力变化，实现了基于遥感技术的历史风力强度的定量化重建。关键词：罗布泊，地形，TerraSAR-X/TanDEM-X，DEM，风应力，湖流模型，历史风力 |
| 英文摘要 | Lop Nur located in a typical area of the extreme drought areas in western China as well as in the whole world, which is highly sensitive to climate change. The lake Lop Nur was a vast water with various resources in history. However, the lake has totally dried up today and leaving nothing but ear-shaped concentric stripes. As the precious resources of nature , the stripes, which recorded the evolution history of the lake, contain climatological and geological information from the quaternary period, thus is important in understanding the evolution law of climate and environment in arid areas and the global climate change in history.The topography of Lop Nur is the foundation in studying the historical information and environmental evolution process of the lake. The comprehensive study of topography and stripes of Lop Nur can provide important information in lake evolution. As the Lop Nur region is flat in terrain and has little changes in elevation, topographic data ever published are hardly to meet the demand of analyzing the topographic characteristic in Lop Nur region, including the data acquired by InSAR technology and modern stereophotogrammetry, which are ten meters or more in accuracy. Although the laser altimeter data has a high accuracy, it is only dot data of cross-section. Besides, several in-situ measurements are limited in quantity and show great contradictions in topography. Presently, the community still comes to no accurate understanding about the precise topographic feature of Lop Nur region in a large and continuous scale. In the thesis, interferometric data collected by TerraSAR-X/TanDEM-X (TSX/TDX) is used in the topographic study of Lop Nur. A high precision Digital Elevation Model (DEM) of Lop Nur region is established by InSAR technique, using TSX/TDX short baseline data. After elevation correction and precision evaluation using Geoscience Laser Altimeter System (GLAS) elevation data, the DEM has an accuracy of 37.6 cm. The DEM clearly shows topographic characteristic of the closed concentric stripes in Lop Nur basin, river network in western, depressions, Loulan city and Linhai city. Besides, the Lop Nur region is flat in terrain and the lowest is in the region with stripes (between 785 and 790 meters). Elevation difference between the adjacent stripe is no more than 1 meter, total elevation difference no more than 5 meter. The outer stripes is higher than the inner ones in elevation, and no so called highland is found in the central part of the region of ear-shaped stripes.With the help of the high precision DEM, we analyzed the elevation along stripes emphatically. The result indicated that the stripes in the north part of the basin is basically the same in elevation, while the elevation of the south shoreline is approximately 1 meter higher than that of the north shoreline along the same stripe, validating the phenomenon of “elevation discrepancy along the same stripe”.According to the wind stress mechanism and lake current model, the difference in elevation of the stripes between the upwind and downwind can be associated with the wind strength. Through error analysis, the elevation difference can be used to represent the main wind strength. With the elevation difference after screening as the wind strength proxy, different stripes represent different historical period, to generate the historical wind strength curve. Finally by using the lake current model for numerical simulation, the wind variation in Lop Nur’s gradually drying up has been represented, and the quantitative reconstruction of historical wind strength has been realized based on remote sensing technology. Keywords: Lop Nur, topography, TerraSAR-X/TanDEM-X, DEM, wind stress, lake current model, historical wind |
| 中文关键词 | 罗布泊 ; 地形 ; TerraSAR-X/TanDEM-X ; DEM ; 风应力 ; 湖流模型 ; 历史风力 |
| 英文关键词 | Lop Nur topography TerraSAR-X/TanDEM-X DEM wind stress lake current model historical wind |
| 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/2XILL650/287815 |
| 推荐引用方式 GB/T 7714 | 谢凯鑫. 罗布泊地区高精度DEM建立及历史风力强度重建[D]. 中国科学院大学,2016. |
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