Knowledge Resource Center for Ecological Environment in Arid Area
| 罗布泊湖盆区域地形特征及形成机制分析 | |
| 其他题名 | Analysis on Topographic Characteristic and its Formation Mechanism in Lop Nor Lake Basin |
| 王龙飞 | |
| 出版年 | 2014 |
| 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圈层纹理，忠实记录着湖泊最后的演化历史，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。 罗布泊地形是研究罗布泊水体变迁和环境演化过程的基础，具有重要的科研价值。结合罗布泊的耳纹形态与精确的地形资料，可以为分析罗布泊演化过程提供重要的基础资料，极大地增进人们对于罗布泊及其变迁的认识。但由于罗布泊地区地势平坦，在近万平方公里的范围内高差仅有数米，目前已有的地形资料，包括立体摄影测量及InSAR等手段获取的地形数据，精度为十数米，难以满足罗布泊湖盆区域地形特征分析的需求，而现有的实地测量结果相互矛盾，因此，对湖盆的准确地形特征的认识一直未能在学界达成一致。 本文首次将星载激光高度计GLAS数据应用于罗布泊研究。针对罗布泊地区的地形特点，分析给出适用于该地区的激光高度计有效数据筛选方案，经过筛选的GLAS有效数据精度达13.8cm。根据GLAS高程剖面数据，确定大罗布泊区内湖盆极为平坦，海拔785-790米，高程相差不超过5米。高程变化主要集中于罗布泊纹理区，特别是耳纹区，耳纹区沿轨平均坡度介于0.09‰与0.15‰之间。罗布泊湖盆纹理由外到内呈现出高程递减的趋势，未发现有“湖心岛”存在。 在以往的研究中，由于高精度测量数据的缺乏，罗布泊环状纹理一直被假定为代表历史湖岸的等高程线。本文结合GLAS和DGPS测量数据，对罗布泊环状纹理高程进行特征分析，研究结果表明罗布泊耳纹区环状纹理呈现北部水平、南部高程逐渐增大的形态，南北最大高差超过1米，存在“同环不同高”现象。 针对罗布泊环状纹理的“同环不同高”现象，论文提出了三种可能的形成机制并进行了详细的讨论，认为环状纹理形成时的风应力是造成罗布泊耳纹“同环不同高”的主要原因。通过建立风应力模型，对风应力造成的湖面以及耳纹高程进行了模拟。结果显示，模拟得到的耳纹高程剖面在形态特征以及南北高差大小上与测量结果吻合程度较高，表明该模型能够很好的解释罗布泊环状纹理的“同环不同高”现象。 |
| 英文摘要 | Lop Nor located in a typical arid region in the world, which is highly sensitive to climate change. The lake Lop Nor was a vast water with various resources in history, and by which ancient oasis civilization developed. However, the lake has totally dried up in the 20th century and leaving nothing but ear-shaped concentric stripes in remote sensing images. The stripes, which recorded the evolution history of the last moment of the lake, contain geological and climatological information from the quaternary period, thus is important in understanding the global climate change in history. The comprehensive study of stripes and topography of Lop Nor can provide important information in lake evolution, which is essential in understanding the history of Lop Nor. The topography of the basin is the foundation in studying the historical information and environmental evolution process. As the Lop Nor lake basin is flat in terrain and has little changes in elevation, varying in several meters, topographic data ever published are hardly to meet the demand of analyzing the topographic characteristic in Lop Nor basin, including the data acquired by modern stereophotogrammetry and InSAR technology, which are ten meters or more in accuracy. Besides, several in-situ measurements show great contradictions in topography. Presently, the community still comes to no agreement on the precise topographic feature of Lop Nor lake basin. In the thesis, elevation data collected by spaceborne laser altimeter Geoscience Laser Altimeter System (GLAS) is used in the study of Lop Nor. The data was carefully studied and a selection scheme of effective dataset is proposed and the conducted results have an accuracy of 13.8cm. The effective dataset of GLAS showed the elevation was between 785 and 790 meters in the Big Lop region. The undulation is mainly in the region with stripes, especially the region with ear-shaped stripes. The along track gradient in elevation is between 0.09‰ and 0.15‰ in the region with ear-shaped stripes. The outer stripes is higher than the inner ones in elevation, and no so called highland with height of 2-3 meters is found in the central part of the region of ear-shaped stripes. Due to lack of high precision measurement, the elevation was supposed to be constant along the same stripe in previous studies. With the help of GLAS and Differential Global Positioning System (DGPS), we analyzed the elevation along stripes. 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. We discussed three possible mechanisms to explain the phenomenon, and suggested that the wind-driven water surface tilt at the time the ear-shaped stripes formed is the dominant one. Corresponding wind stress model is proposed to simulate the profile of the water surface and ear-shaped stripes. The stripe profiles simulated by this mechanism showed an excellent agreement with the measured stripe profiles. |
| 中文关键词 | 罗布泊 ; 地形 ; “同环不同高” ; 激光高度计GLAS ; 风应力 |
| 英文关键词 | Lop Nor topography elevation discrepancy along the same stripe GLAS wind stress |
| 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/2XILL650/287454 |
| 推荐引用方式 GB/T 7714 | 王龙飞. 罗布泊湖盆区域地形特征及形成机制分析[D]. 中国科学院大学,2014. |
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