摘要 地熱能源是全球綠色能源日益重要的成分。地熱能源開發的先決條件是地方和區域性的地熱探勘，實務上由於探勘現場的運行成本和場址可達性，現行探勘或監測地熱資源的地球物理方法通常受限於局部範圍，因此大規模區域的探勘或監測(例如表面溫度和地熱異常)主要仰賴於衛星熱紅外影像技術。本研究旨在將熱紅外(TIR)遙測技術與現有地球物理方法結合運用於台灣北部的地熱探勘與火山監測上面。 本文研究區域為台灣北部地熱的兩個高潛能區：1)台灣東北的宜蘭平原；2)台灣北部的大屯火山群(TVG)。首先以地球資源衛星Landsat 7 ETM + 的影像來反演估算宜蘭平原和TVG的地表溫度(LST)，再通過與11個常設氣象站的氣溫數據進行比較分析，對衛星估算的地表溫度(LST)進行精度評估，結果顯示氣溫數據與反演的LST線性回歸的相關係數為0.76，最後將LST結果加以非監督分類得到LST分類圖，進而分析宜蘭平原與TVG的地熱異常型態。MODIS LST產品也用來交叉驗證了Landsat LST的可靠性，另外從1999至2016年的Landsat ETM +多時亮溫圖也用來檢驗了LST異常型態分布。 應用TIR遙測在宜蘭平原的結果顯示，地熱異常區域的分布與斷層的位置相關聯。將地熱異常區域和溫泉和地熱井的現場調查進行驗證，發現非都市區的溫泉和地熱井的位置與地熱異常區域有很好的一致性。此外，針對清水地熱區進行詳細比較分析，發現由大地電磁法所獲得的電阻率剖面中的低電阻率區域與LST剖面中的低地溫區相當吻合。 應用TIR遙測在TVG的研究中，使用Landsat 7 ETM + 影像反演估算地表溫度(LST)和輻射熱通量(RHF)，並採用搭載在Aqua衛星上的MODIS感測器之LST產品(2002-2016年)對TVG的金山斷層帶加以時序分析。結果表明，衛星反演的LST異常區與溫泉和火山噴氣孔區域吻合；且TVG的東西方向火山山脊的平均溫度要高於東北西南方向山脊。地熱異常型態顯示LST的高溫區分佈與金山斷層區的位置一致，為了進一步探究兩者的相關性，本文採用希爾伯特-黃轉換(HHT)分析金山斷層區2002至2016年間的MODIS LST時間序列，並討論分析整體平均的經驗模態分解(EEMD，是HHT的主要成分)分量中蘊含的物理過程。其中特別深入研究了C1分量(即EEMD分量1，具有大約一個月的平均週期)中的不規則尖峰可能與TVG地區的地震活動相關聯之推論。最後，為評估TVG的噴發潛力，本文對在菲律賓和印度尼西亞的三座活火山進行了HHT結果的綜合比較分析。 總言， 此研究結果突顯了衛星熱紅外遙測反演估算LST的效果，並採用了HHT數據分析方法來對MODIS LST時間序列進行有效的分析。在宜蘭平原和大屯火山群的研究表明， TIR遙測是探勘和量化地熱和火山地區表面特徵的重要技術與方法，此法與其他地球物理方法相得益彰有效加強了對研究區域的了解，其資料處理結果快速且具有高成本效益。 ;Abstract Geothermal energy is an increasingly important component of renewable and green energy in the globe. A prerequisite for geothermal energy development is to acquire the local and regional geothermal prospects. Existing geophysical methods of monitoring or exploring the geothermal resource are usually limited to the scope of prospecting because of the operation cost and site reachability in the field. Thus monitoring or explorations in a large-scale area such as the surface temperature and the thermal anomaly primarily rely on satellite thermal infrared imagery. This research aims to apply and integrate Thermal Infrared (TIR) Remote Sensing technology with existing geophysical methods for the geothermal exploration and volcanic monitoring in northern Taiwan. Two hot potential sites of geothermal energy in Taiwan have been studied in this research. Namely, 1) Ilan Plain of northeastern Taiwan; 2) Tatun Volcanic Group (TVG) of northern Taiwan. Thermal Infrared Remote Sensing technology has been applied for both sites. Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) imagery is used to retrieve the Land Surface Temperature (LST) in Ilan Plain and TVG. Accuracy assessment of satellite derived LST is conducted by comparing with the air temperature data from 11 permanent meteorological stations. The correlation coefficient of linear regression between air temperature and LST retrieval is 0.76. The MODIS LST product is used for the cross validation of Landsat derived LSTs. Furthermore, Landsat ETM+ multi-temporal brightness temperature imagery from 1999 to 2016 for the verification of the LST anomaly results were performed. Results from the application of TIR remote sensing in Ilan Plain indicate that thermal anomaly areas appear spatially correlating with the development of faulted structure. Selected geothermal anomaly areas are validated in detail by the field investigation of hot springs and geothermal drillings. It implies that occurrences of hot springs and geothermal drillings are in good agreement with anomaly areas. In addition, the significant low-resistivity zones observed in the resistivity sections are echoed with the LST profiles when compared with in the Chingshui geothermal field. For the application of TIR remote sensing in TVG, Landsat 7 thermal infrared imagery was used to retrieve the LST and Radiative Heat Flux (RHF), and MODIS LST products were analyzed for the Jinshan fault area in TVG. Detected LST anomaly areas are validated by the field investigation of hot springs and fumaroles. It implies that occurrences of hot springs and fumaroles conform to anomaly areas. The overall temperature in E-W ridge is hotter than the SW-NE ridge in TVG. Thermal anomaly patterns also indicate that distributions of higher LST areas appear correlating with the development of Jinshan fault. Besides, Hilbert Huang Transform (HHT) was adopted for analyzing MODIS LST time series (2002-2016) in Jinshan fault area. Possible related physical processes underneath of Ensemble Empirical Mode Decomposition (EEMD) components which are the key parts of HHT were also discussed. The inference that LST component with average period around a month (EEMD component 1, i.e. C1) has irregular spikes which is possibly associated with earthquakes in TVG has been investigated in detail. Finally, HHT comparison analysis with three active volcanoes in Philippines and Indonesia is performed for attempting to assess the eruption potential of TVG. The effectiveness of satellite thermal infrared remote sensing in retrieval of LST using Landsat images was demonstrated. And the usefulness of HHT data analysis method on MODIS LST time series was also presented. Despite limited to detecting the surficial and the shallow buried geothermal resources, the work in Ilan Plain and TVG suggests that TIR Remote Sensing is a valuable tool for mapping and quantifying surface features to expand the understanding and enhance the knowledge of the geothermal and volcanic areas with less time-consuming and high cost-efficiency.
