The ice content of palsas and peat plateaus, estimated with high-frequency induced polarisation

泥煤和泥炭是由永久冻土形成的特殊地貌。它们覆盖了加拿大、俄罗斯欧洲部分、西伯利亚和北方芬诺斯堪的亚北极地区的广大地区。这些地貌储存了大量的碳和氮，这些碳和氮可能会因全球变暖而释放到地球大气中。因此，它们可能有助于反馈机制并加速气候变化。冻土中的冰含量是控制冻土对温度升高的敏感程度的基本量。冰含量也是任何试图预测气候变化条件下棕榈和泥炭高原退化的数值模拟的关键参数。同时，冰含量及其空间变化很难在了解退化过程细节所需的分辨率下测量。在这个项目中，我们将采用一种创新的地球物理方法，高频诱导极化，以确定冰含量下特定的棕榈和泥炭高原在芬诺斯坎迪亚。该方法在1Hz和250kHz之间的频率范围内确定频率相关的电特性（电导率和介电常数）。由于冷冻水的介电常数在该频率范围内表现出特征行为，因此该方法适合于估计冰含量。最近，它表明，冰含量估计是可能的，在真实的条件下，在现场尺度。我们将在挪威北方选定的四个地点进行测量，并确定冰含量及其空间变化。在一个地点，我们将进行重复调查，以捕捉地下条件随时间的变化，这是众所周知的是相当迅速。我们的研究结果将提供一个基础，在全球变暖的背景下，推进棕榈和泥炭高原的命运的预测。 这些数据将有助于缩小数值模拟的要求与缺乏实际地面资料之间的差距。Fennoscandia的研究地点是大型亚北极地区的代表，因此，对了解冻土退化的贡献将具有全球意义。

Palsas and peat Pleateaus are specific landforms that are shaped by processes in permanently frozen ground. They cover extensive areas in subarctic regions in Canada, European Russia, Siberia and Northern Fennoscandia. The landforms store a significant amount of Carbon and Nitrogene, which might be released into Earth’s atmosphere by global warming. Therefore, they may contribute to feedback mechanisms and accelerate climate change. Ice content in frozen ground is an essential quantitiy that controls how sensitive frozen ground is to a temperature increase. Ice content is also a key parameter for any numerical simulation trying to predict the degradation of palsas and peat plateaus under climate change conditions. At the same time, ice content and its spatial variation is difficult to measure at a reolution required to understand the details of degradation processes. In this project, we will apply an innovative geophysical method, high-frequency induced polarisation, to determine ice content under specific palsas and peat plateaus in Fennoscandia. The method determines the frequency-dependent electrical properties (electrical conductivity and permittivity) in a frequency range between 1Hz and 250kHz. Since the electric permittivity of frozen water exhibits a characteristic behavior in that frequency range, the method is suitable to estimate ice content. Recently, it was demonstrated that ice content estimation is possible und real conditions at the field scale. We will carry out measurements at four selected in Northern Norway and determine ice content and its spatial variation. At one site, we will carry out repetitive surveys in order to capture the variation of subsurface conditions with time, which is known to be quite rapid. Our results will provide a basis to advance the prediction of the fate of palsas and peat plateaus in the context of global warming. The data will constitute a step towards closing the gap between the requirements of numerical simulation, and the lack of actual ground information. The studied sites in Fennoscandia are representative of large subarctic regions, and therefore the contributions to the understanding of permafrost degradation will be of global relevance.