Improved environmental monitoring of surface geothermal features through comparisons of thermal infrared, satellite remote sensing and terrestrial calorimetry
Improved environmental monitoring of surface geothermal features through comparisons of thermal infrared, satellite remote sensing and terrestrial calorimetry
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DOI：
10.1016/j.geothermics.2018.01.007
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发表时间：
2018-05-01
期刊：
影响因子：
3.9
通讯作者：
Bromley, Chris
中科院分区：
文献类型：
--
作者：
Seward, Anya;Ashraf, Salman;Bromley, Chris
评估地热活动区地表热损失的变化有助于深入了解地热储藏层。蒸汽加热地面的表面温度和热输出可以通过处理热红外图像以及通过使用地面热量计进行直接测量来推断。2014年2月，在新西兰陶波火山带的卡拉皮提(约0.35公里(在怀拉凯-陶哈拉地热系统中))上空进行了高分辨率航空热红外(TIR)调查和地面热损失调查(不包括富马尔放电)。热损失的估计与该地区陆地卫星8号收集的TIR数据计算的热损失进行了比较。本文讨论了数据集的处理技术，并对推断的表面热损失进行了比较。空中TIR和地面测量结果与计算的卡拉皮蒂地表热损失值合理吻合，范围从41 mW(使用空中TIR的理论辐射热损失)到58 mW(基于与沸点深度的经验关联式的总热损失)。卫星图像显示，白天和夜间的TIR评估之间存在很大差异。夜间(非太阳)辐射热损失的评估比其他技术确定的总热损失低一个数量级，并且大约是从空中TIR数据计算得出的辐射分量的三分之一。这很可能是扩散、平流蒸汽热损失的结果，再加上图像分辨率问题：卫星图像的像素分辨率(30x30m)远远大于活跃的地热表面现象的典型尺寸(<；10m(2))。由于辐射热损失是地表温度的非线性函数，像元平均低估了辐射热损失。这些问题和其他问题目前限制了重复的低分辨率卫星图像在监测蒸汽加热地面的地表热损失变化方面的作用。
Assessing changes in surface heat-loss at geothermally active areas provides insight into the geothermal reservoirs at depth. Surface temperatures and heat output of steam-heated ground can be inferred through processing of thermal infrared images, as well as by direct measurements using terrestrial calorimetry. In February 2014, a high resolution aerial thermal infrared (TIR) survey and a terrestrial heat-loss survey (excluding fumarole discharge) were carried out over Karapiti (ca. 0.35 Km(2) in the Wairakei-Tauhara Geothermal System) in the Taupo Volcanic Zone, New Zealand. Estimates of heat-loss are compared to those calculated from TIR data collected by the Landsat-8 satellite of the area. This paper discusses the processing techniques for the datasets and compares inferred surface heat losses. The aerial TIR and terrestrial measurements are in reasonable agreement with calculated surface heat-loss values for Karapiti range from 41 MW (theoretical radiation heat loss using aerial TIR) to 58 MW (total heat loss based on an empirical correlation with boiling-point depths). Satellite images show a large variation between day-time and night-time TIR assessments. The assessment of nocturnal (non-solar), radiation heat-loss is an order of magnitude lower than the total heat-loss determined from the other techniques and approximately 1/3 of the inferred radiated component calculated from the aerial TIR data. This is likely to be a consequence of diffuse, advecting-steam heat-loss, combined with an image resolution issue: the pixel resolution of the satellite image (30 x 30 m) is much larger than the typical size of the active geothermal surface manifestations (< 10 m(2)). Because the radiated heat-loss is a non-linear function of land surface temperature, the in-pixel averaging under-estimates the radiated heat-loss. These and other problems currently restrict the usefulness of repeat low-resolution satellite imagery for monitoring of surface heat loss changes in steam-heated ground.