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

帕尔萨斯和泥炭高原的冰含量，用高频激发极化估算

• 批准号: 524890275
• 负责人: Professor Dr. Andreas Hördt
• 金额: --
• 依托单位: Institut für Geophysik und Extraterrestrische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/524890275?language=en
• 关键词: ice; content; palsas; peat; plateaus

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.

PALSA和PEAT PLEATEAUS是特定的地貌，它们是由永久冷冻地面的过程形成的。它们涵盖了加拿大，欧洲俄罗斯，西伯利亚和北部芬诺斯坎迪亚的亚北极地区的广泛地区。地貌存储了大量的碳和氮，可以通过全球变暖将其释放到地球大气中。因此，它们可能有助于反馈机制并加速气候变化。冷冻地面中的冰含量是一个基本数量，它可以控制敏感的冷冻地面对温度升高的程度。对于任何数值模拟，试图预测在气候变化条件下PALSA和PEARL高原的降解的任何数值模拟也是一个关键参数。同时，很难以了解降解过程的细节所需的分辨率来测量冰含量及其空间变化。在该项目中，我们将采用一种创新的地球物理方法，即高频诱导的极化，以确定芬诺斯卡迪亚（Fennoscandia）在特定的PALSA和Peel Plateaus下的冰含量。该方法确定频率依赖性电性能（电导率和介电常数）在1Hz至250kHz之间的频率范围。由于冷冻水的电介电常数在该频率范围内表现出特征性的行为，因此该方法适合估计冰含量。最近，证明冰含量估计是在现场尺度上可能的实际条件。我们将在挪威北部选定的四个选择中进行测量，并确定冰含量及其空间变化。在一个地点，我们将进行重复的调查，以便随时间捕获地下条件的变化，这是很快的。我们的结果将提供一个基础，以推动在全球变暖的背景下预测PALSA和PEEL PLAPEAUS的命运。数据将构成缩小数值模拟要求与缺乏实际地面信息之间差距的一步。 Fennoscandia的研究菌位点代表了大型亚北极区域，因此，对对多年冻土降解的理解的贡献将具有全球相关性。