| Summary: | Permafrost environments cover vast expanses of polar and mountainous regions. They are difficult to monitor since permafrost is a subsurface phenomenon. The amount of ground ice in the active layer and permafrost affects the thaw depth and response of sedimentary deposits to climate warming. The loss of ground ice also has pronounced impacts on terrain stability. Previous studies have investigated the use of Interferometric Synthetic Aperture Radar (InSAR) remote sensing to monitor seasonal surface displacement related to the freeze-thaw cycle, as well as long-term surface displacements caused by ground ice degradation or aggradation. InSAR could help to monitor ground ice changes and the surface displacement timeseries might help to constrain the ground ice parameterization of permafrost models. However, in-situ validation of InSAR displacements is sparse and the alignment between modelled ground ice dynamics and InSAR displacements has so far not been investigated. This thesis aimed to validate seasonal and interannual InSAR displacements through field validation. It was further tested, if the InSAR displacements align with simulated ground ice changes. For this, field validation data of active layer and permafrost ground ice contents was collected in spring and autumn 2023 in Adventdalen, Svalbard. InSAR displacement timeseries were created for seasonal and interannual displacements over the period 2018-2023. The seasonal InSAR displacement was compared to the expected subsidence from ground ice melt, and a good agreement was found. Excess ice melt and drainage dominate the expected subsidence, and thus there was a poor relationship between subsidence magnitude and active layer thickness. This has implications for inverting active layer thickness from seasonal InSAR displacements, and has previously not been considered. The interannual InSAR displacements show long-term subsidence in locations where field results revealed an ice-rich uppermost permafrost, whilst locations with an ice-poor uppermost permafrost ...
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