本文關(guān)鍵詞： 交叉干涉技術(shù) 高程模型 ERS ENVISAT 埃默里冰架　出處：《北京建筑大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

【摘要】：合成孔徑雷達(dá)干涉技術(shù)（InSAR）可利用由空間軌道略微差別所產(chǎn)生的回波雷達(dá)信號(hào)的相位差來探測地表的微小變化，為測量冰蓋和冰川以及他們的表面高程等參數(shù)開拓了一條道路。但I(xiàn)nSAR在冰架表面高程的提取中具有很大難度，原因在于干涉影像對(duì)獲取時(shí)間間隔如果過長，冰架的水平冰流運(yùn)動(dòng)和垂直的潮汐運(yùn)動(dòng)會(huì)導(dǎo)致影像間失去相關(guān)性，進(jìn)而無法準(zhǔn)確獲取高程信息。歐空局的第三次ERS和ENVISAT編隊(duì)串聯(lián)飛行任務(wù)（EET）為利用InSAR技術(shù)獲取冰架表面高程的研究帶來了機(jī)會(huì)，其任務(wù)飛躍南極上空時(shí)，干涉影像對(duì)時(shí)間間隔僅為28分鐘，且EET的交叉干涉影像對(duì)有2公里的空間基線，使得干涉對(duì)地形變化十分敏感，高程模糊度僅為5米。 本文研究充分利用EET數(shù)據(jù)的優(yōu)勢，以東南極的埃默里冰架為例，選取合適EET交叉干涉影像對(duì)，經(jīng)過預(yù)處理，得知試驗(yàn)數(shù)據(jù)的空間基線和多普勒質(zhì)心差滿足EET交叉干涉的條件，保證了除了冰流一致性的運(yùn)動(dòng)外，在觀測間隔期間沒有其他變形發(fā)生（例如潮汐運(yùn)動(dòng)）。并采用200米分辨率的RAMP高程模型作為參考高程，，進(jìn)行高程信息提取，獲取了高空間分辨率（25米）的高程圖，結(jié)果顯示提取的高程結(jié)果能準(zhǔn)確的表現(xiàn)冰架表面的精細(xì)結(jié)構(gòu)特征，垂直精度已經(jīng)達(dá)到米級(jí)單位。 本文依據(jù)實(shí)踐結(jié)果對(duì)提取方法進(jìn)行了改進(jìn)，主要體現(xiàn)在：（1）根據(jù)相干圖結(jié)果進(jìn)行分析，表明在平坦的冰架區(qū)域有較好的可視結(jié)果，而在山地區(qū)域的解纏相位較差，因此在處理過程中對(duì)影像進(jìn)行了適當(dāng)裁剪，有效地避免了山地區(qū)域?qū)φw影像解纏的影響。 （2）對(duì)冰架區(qū)域的不同流速和不同干雪類型地表覆蓋進(jìn)行了分析，發(fā)現(xiàn)它們對(duì)結(jié)果的影響較小，基本可以忽略，最終發(fā)現(xiàn)所獲取的高程誤差主要是衛(wèi)星基線不準(zhǔn)確所帶來的，因此本文采用GLAS點(diǎn)代替?zhèn)鹘y(tǒng)選取的控制點(diǎn)來重新估算基線去除殘差。應(yīng)用Cryosat-2和少量GPS數(shù)據(jù)與修正前后的高程結(jié)果進(jìn)行比較，確認(rèn)修改方法對(duì)結(jié)果有明顯的改進(jìn)。在埃默里冰架的實(shí)驗(yàn)表明，EET的交叉干涉技術(shù)可實(shí)現(xiàn)冰架高分辨率高精度高程模型的獲取。
[Abstract]:The synthetic Aperture Radar Interferometry (InSAR) can detect small changes in the surface using the phase difference of echo radar signals generated by slight differences in space orbits. It opens a way to measure ice caps and glaciers and their surface elevation. But InSAR is very difficult to extract from ice shelf surface elevation because the interference image is too long for the acquisition time interval. The horizontal ice flow movement and the vertical tidal movement of the ice shelf have led to a loss of correlation between the images, The third ERS and ENVISAT formation series flight mission of ESA offers an opportunity to use InSAR technology to obtain the surface elevation of the ice shelf, whose mission is flying over the South Pole. The interval between interference images is only 28 minutes, and the cross-interference images of EET have a spatial baseline of 2 km, which makes the interference very sensitive to terrain changes, and the height ambiguity is only 5 meters. In this paper, the advantage of EET data is fully utilized. The Emory ice shelf in east Antarctica is taken as an example, and the suitable EET cross interference image pair is selected. After preprocessing, it is found that the spatial baseline and Doppler centroid difference of the experimental data meet the condition of EET cross interference. Besides the consistent motion of ice flow, there are no other deformations (such as tidal motion) during the observation interval. The 200m resolution RAMP elevation model is used as the reference height to extract the elevation information. The height map with high spatial resolution of 25 m) is obtained. The results show that the extracted elevation can accurately represent the fine structure characteristics of the ice shelf surface, and the vertical accuracy has reached the meter level unit. In this paper, the extraction method is improved according to the practical results, mainly reflected in the analysis of the results of the coherence map. The results show that there are better visual results in the flat ice shelf area, but the unwrapping phase is poor in the mountainous area. Therefore, in the process of processing, the image is cut properly, which effectively avoids the influence of the mountainous region on the whole image unwrapping. (2) the surface coverage of different velocity and dry snow types in the ice shelf area is analyzed. It is found that they have little influence on the results and can be neglected. Finally, it is found that the elevation error obtained is mainly caused by the inaccurate satellite baseline. Therefore, in this paper, GLAS points are used to replace the traditional control points to reestimate the baseline to remove the residual errors. The Cryosat-2 and a small amount of GPS data are compared with the corrected elevation results. The experimental results at Emory Ice Shelf show that the cross interference technique of EET can obtain the high resolution and high precision elevation model of the ice shelf.
【學(xué)位授予單位】：北京建筑大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：P225.1;P224

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