過去單一觀測角干涉雷達應用受限於單一斜距向位移觀測，隨著 ENVISAT、ALOS/PALSAR與RADARSAT-2等星載雷達發射運作，多觀測角度或多偏極組態方式拍攝，增加地變形觀測機會。地變形觀測重要性在於伴隨產生災害的威脅，常見的兩種地表地變形形態，其一瞬間大規模地變形(如集集地震或汶川地震等)造成重大災害，其二微量地變形(如台灣西部地區地層下陷或台南台地抬昇)，也間接威脅著台灣高速鐵路運行。
本研究提出以多組態星載干涉雷達方法，藉由不同時段、不同觀測角度或不同偏極觀測組態干涉雷達所觀測斜距變量，以成本(Cost)函數描述其間三維地變形量與各觀測斜距變量幾何關係，以最小成本方法解算出下陷量場；加以長期多次觀測變量，另藉由地變形模式設計，同理以成本函數描述各時間地變形量，以最小成本方法解算下陷中心地變形量隨時間變化。
本研究以歐洲ENVISAT的C波段ASAR與日本ALOS上的L波段PALSAR星載雷達干涉雷達對於彰化雲林地區下陷情形自2006年12月至2009年元月進行觀測，其中包含昇、降模式差分干涉觀測，以最小成本函數方法解決過去單一斜距變量觀測，對西部沿海地區地層下陷作反演分析，以推估西部沿海地區地層下陷範圍及趨勢；與傳統水準測量比較具一致性，在沿台灣高鐵附近呈現兩下圓狀陷區域。另藉由地變形模式設計成本函數描述各時段地變形量，以最小成本方法解算集集地震前員林下陷中心與台南台地抬昇中心地變形量隨時間變化。本方法有助應用於未來星載雷達多觀測角度或多偏極觀測組態運作方式下，兼顧地變形觀測應用。

The new generation spaceborne SAR are more complicated within radar interferometry application due to more flexible operation as multi-beam and multi-polarization like as ENVISAT、ALOS/PALSAR、Radarsat-2 and TerraSAR-X etc. The prevailing complex geological condition of Taiwan have drawn considerable attention from various geological communities to produce various natural hazards at different scales. Located in the tropical/subtropical zone of the Pacific Rim, its ecological and rugged mountainous properties are environmentally sensitive making monitoring and observations especially difficult because of the high population density.
The main limitation of 3D deformation measurements made with interferometry is that interferogram gives only give the line-of-sight direction is measured. In this study proposes a new approach using the cost function to integrate of multi-modal spaceborne radar interferograms within multi-beam or both ascending and descending. Minimized the cost function and extracted the subsidence deformation map. In the meantime, we considered the deformation type and proposed the temporal deformation models with minimized cost function for long-term interferometric observation. The study case used the period of observations dated from Dec. 2006 to Jan. 2009 with pairs from C-band ASAR/ENVISAT and L-band PALSAR/ALOS data sets were used to detect and track the deformations. With both ascending and descending orbits, the manner further improved the subsidence mapping. That result is better comparisons with the precision leveling survey in 2005. Both ascending and descending mapping results indicate that the maximum subsidence rates were about 7 cm/yr (around epicenter) in that period. Another topic within deformation model within the long-term observation to find the temporal deformation profile such as Yuanlin subsidence event before ChiChi earthquake and Tainan tableland uplift.

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