Abstract In cold regions where soils freeze and thaw annually, the ground surface deforms due to the density difference between groundwater and ground ice. Here we mapped thaw subsidence and frost heave signals over the Toolik Lake area on the North Slope of Alaska using 12 ALOS PALSAR Interferometric Synthetic Aperture Radar (InSAR) scenes (2006–2010). For the first time, we jointly analyzed InSAR observations with a large number of soil measurements collected within ~ 100 km of the Toolik Field Station. We found that the InSAR-observed deformation patterns are mainly related to soil water content and the seasonal active layer freeze-thaw (FT) cycle. We did not observe any substantial long-term subsidence trend outside the 2007 Anaktuvuk River Fire scar. This suggests that the magnitude of the maximum annual thaw subsidence did not change much outside the fire zone during the study period. The joint analysis of InSAR and field observations allows us to show that the amplitude of the seasonal thaw subsidence is proportional to the total amount of ice that has melted into liquid water at any given time. We note that topography influences the spatial distribution of soil water content, and the availability of soil water influences the type of vegetation that can grow. As a result, we found that the average seasonal thaw subsidence increases along a geomorphic-ecohydrologic transect with heath vegetation on the drier ridge-tops, tussock tundra on hillslopes, and sedge tundra at the wet lowland riparian zones. In addition, we detected a net uplift between late July and early September, mostly in the wetter riparian zone that experienced a larger seasonal thaw subsidence. Toolik Field Station in-situ records suggest that the air temperature fluctuated around or below freezing in early September during the ALOS PALSAR data acquisition times (at ~ 12 am local time). In this scenario, ice can be formed at the top of the soil, which leads to frost heave in saturated soils. Our results highlight how InSAR can improve our understanding of active layer freeze-thaw and water storage dynamics in permafrost environments.

中文翻译：

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从 InSAR 推断的多年冻土环境中活动层冻融和储水动态

摘要 在土壤每年冻融的寒冷地区，由于地下水和地冰的密度差异，地表变形。在这里，我们使用 12 个 ALOS PALSAR 干涉合成孔径雷达 (InSAR) 场景（2006-2010 年）绘制了阿拉斯加北坡 Toolik 湖地区的解冻沉降和冻胀信号。我们首次联合分析了 InSAR 观测结果，并在距离 Toolik 现场站约 100 公里范围内收集了大量土壤测量值。我们发现 InSAR 观测到的变形模式主要与土壤含水量和季节性活动层冻融 (FT) 循环有关。除了 2007 年 Anaktuvuk 河火灾疤痕之外，我们没有观察到任何实质性的长期沉降趋势。这表明在研究期间，最大年融化沉降的幅度在火区外没有太大变化。InSAR 和现场观测的联合分析使我们能够表明，季节性融化沉降的幅度与在任何给定时间融化成液态水的冰总量成正比。我们注意到地形影响土壤含水量的空间分布，土壤水分的可用性影响可以生长的植被类型。结果，我们发现平均季节性融化沉降沿着地貌-生态水文断面增加，干燥的山脊顶部有荒地植被，山坡上有草丛苔原，潮湿低地河岸带莎草苔原。此外，我们在 7 月底和 9 月初之间检测到净抬升，主要在经历了较大季节性融化沉降的潮湿河岸带。Toolik 现场站现场记录表明，在 ALOS PALSAR 数据采集时间（当地时间上午 12 点左右）期间，9 月初的气温在零度左右或零度以下波动。在这种情况下，土壤顶部会形成冰，从而导致饱和土壤中的冻胀。我们的结果突出了 InSAR 如何提高我们对多年冻土环境中活动层冻融和水储存动态的理解。土壤顶部会形成冰，从而导致饱和土壤中的冻胀。我们的结果突出了 InSAR 如何提高我们对多年冻土环境中活动层冻融和水储存动态的理解。土壤顶部会形成冰，从而导致饱和土壤中的冻胀。我们的结果突出了 InSAR 如何提高我们对多年冻土环境中活动层冻融和水储存动态的理解。