Knowledge of the amount of unfrozen water and its migration in permafrost soils is important for understanding physico‐chemical and biological processes. Here, we developed sub‐routines in FREZCHEM and embedded them in the WATEREGO2 soil environmental model to: (a) estimate unfrozen water content under changing soil temperatures and water–ice phase changes; and (b) determine the effects of Van der Waals (VdW) and rheological forces driven by seasonal temperature variations on the transport of residual water and the long‐term evolution of ground ice content over depths of 30 m. Together, the seasonal thermal regime and associated VdW and rheological forces on the transport of residual water lead to the evolution of distinct zones of ice‐enrichment: near the surface of permafrost, at 3–5 m, 11–13 m and 17–19 m depth. The depths of ice enrichment are a function of soil thermal diffusivity, and the time needed to evolve the ground ice content is dependent on soil type, soil water chemistry and permafrost temperature. The model can explain observed variations with depth in ground ice content of icy permafrost soils and indicate that these conditions evolve over time. The findings can be used to assess the stability of permafrost to climate change under different temperature scenarios.

中文翻译：

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冰冻多年冻土中未冻结水分及其迁移的模型：对地面冰含量和多年冻土稳定性的影响

了解未冻水的数量及其在多年冻土中的迁移对于了解理化和生物过程非常重要。在这里，我们在FREZCHEM中开发了子例程，并将其嵌入到WATEREGO2土壤环境模型中，以：（a）在土壤温度变化和水冰相变化的情况下估计未冻结的水分；（b）确定季节性温度变化驱动的范德华力（VdW）和流变力对残留水的运输以及30 m深度的地面冰含量的长期演变的影响。总的来说，季节性的热状态以及相关的VdW和流变力对残余水的输送导致了冰的富集区的演变：在永久冻土表面附近的3-5 m，11-13 m和17-19米深。冰的富集深度是土壤热扩散率的函数，演化地下冰含量所需的时间取决于土壤类型，土壤水化学和多年冻土温度。该模型可以解释观察到的冰冻土的地下冰含量随深度的变化，并表明这些条件随时间而变化。这些发现可用于评估不同温度情景下多年冻土对气候变化的稳定性。