Two-dimensional inversion of wideband spectral data from the capacitively coupled resistivity method – first applications in periglacial environments
Two-dimensional inversion of wideband spectral data from the capacitively coupled resistivity method – first applications in periglacial environments
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DOI：
10.5194/tc-13-2439-2019
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
J. Mudler;A. Hördt;A. Przyklenk;G. Fiandaca;P. Maurya;C. Hauck
中科院分区：
文献类型：
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作者：
J. Mudler;A. Hördt;A. Przyklenk;G. Fiandaca;P. Maurya;C. Hauck
抽象的。直流电阻率法是冰缘研究中的常用工具，因为它可以描绘出大电导率区域，而这些区域通常与冻结水有关。然而，这种解释可能是模棱两可的，因为大的孔隙率也可能有其他原因，比如固体干燥的岩石。减少模糊性的一种可能性是测量频率相关的电阻率。在低频率（<100 Hz）下，相应的方法称为激发极化，也用于冰缘环境。对于水冰的检测和可能的量化，在100 Hz和100 kHz之间的较高频率范围可能是特别令人感兴趣的，因为在该范围内，水冰的电特性表现出特征性行为。此外，大频率允许电极的电容耦合，这可能具有后勤优势。电容耦合电阻率（CCR）方法试图将这些逻辑优势与减少模糊性的潜在科学效益联合收割机结合起来。在本文中，我们讨论CCR数据获得的两个领域的网站与冰冻圈的影响：在瑞士阿尔卑斯山的Schilthorn的雪夫和冰冻的普雷斯特万内特湖在挪威的北方的一部分。一个目标是增加文献中的例子，在不同的条件下评估的方法。我们的研究结果与已知的地下结构相当吻合：在Prestvannet站点，从冰冻湖泊到陆地的过渡在反演结果中清晰可见，而在Schilthorn站点，积雪和下面的基岩之间的边界可以很好地划定。在这两种情况下，电气参数与文献中预期的一致。第二个目标是讨论有用的方法的进步：首先，我们调查的电容传感器的表面以上的高度的影响，并证实了假设，它是可以忽略不计的高阻条件。对于数据的反演，我们修改了最初为低频激发极化数据开发的现有2-D反演代码，加入了介电常数的参数化。新的反演代码允许提取的电气参数，可以直接与文献值，这是以前不可能的。
Abstract. The DC resistivity method is a common tool in periglacial research because it can delineate zones of large resistivities, which are often associated with frozen water. The interpretation can be ambiguous, however, because large resistivities may also have other causes, like solid dry rock. One possibility to reduce the ambiguity is to measure the frequency-dependent resistivity. At low frequencies (< 100 Hz) the corresponding method is called induced polarization, which has also been used in periglacial environments. For the detection and possibly quantification of water ice, a higher frequency range, between 100 Hz and 100 kHz, may be particularly interesting because in that range, the electrical properties of water ice exhibit a characteristic behaviour. In addition, the large frequencies allow a capacitive coupling of the electrodes, which may have logistical advantages. The capacitively coupled resistivity (CCR) method tries to combine these logistical advantages with the potential scientific benefit of reduced ambiguity. In this paper, we discuss CCR data obtained at two field sites with cryospheric influence: the Schilthorn massif in the Swiss Alps and the frozen Lake Prestvannet in the northern part of Norway. One objective is to add examples to the literature where the method is assessed in different conditions. Our results agree reasonably well with known subsurface structure: at the Prestvannet site, the transition from a frozen lake to the land is clearly visible in the inversion results, whereas at the Schilthorn site, the boundary between a snow cover and the bedrock below can be nicely delineated. In both cases, the electrical parameters are consistent with those expected from literature. The second objective is to discuss useful methodological advancements: first, we investigate the effect of capacitive sensor height above the surface and corroborate the assumption that it is negligible for highly resistive conditions. For the inversion of the data, we modified an existing 2-D inversion code originally developed for low-frequency induced polarization data by including a parametrization of electrical permittivity. The new inversion code allows the extraction of electrical parameters that may be directly compared with literature values, which was previously not possible.