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    Numerical modeling of two-dimensional temperature dynamics across ice-wedge polygons

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    Author
    Garayshin, Viacheslav Valer'evich
    Гарайшин, Вячеслав Валерьевич
    Chair
    Romanovsky, Vladimir
    Rybkin, Alexei
    Committee
    Nicolsky, Dmitry
    Hinzman, Larry
    Metadata
    Show full item record
    URI
    http://hdl.handle.net/11122/7602
    Abstract
    The ice wedges on the North Slope of Alaska have been forming for many millennia, when the ground cracked and the cracks were filled with snowmelt water. The infiltrated water then became frozen and turned into ice. When the annual and summer air temperatures become higher, the depth of the active layer increases. A deeper seasonal thawing may cause melting of ice wedges from their tops. Consequently, the ground starts to settle and a trough begins to form above the ice wedge. The forming trough creates a local temperature anomaly in the surrounding ground, and the permafrost located immediately under the trough starts degrading further. Once the trough is formed, the winter snow cover becomes deeper at the trough area further degrading the permafrost. In this thesis we present a computational approach to study the seasonal temperature dynamics of the ground surrounding an ice wedge and ground subsidence associated with ice wedge degradation. A thermo-mechanical model of the ice wedge based on principles of macroscopic thermodynamics and continuum mechanics was developed and will be presented. The model includes heat conduction and quasi-static mechanical equilibrium equations, a visco-elastic rheology for ground deformation, and an empirical formula which relates unfrozen water content to temperature. The complete system is reduced to a computationally convenient set of coupled equations for temperature, ground displacement and ground porosity in a two-dimensional domain. A finite element method and an implicit scheme in time were utilized to construct a non-linear system of equations, which was solved iteratively. The model employs temperature and moisture content data collected from a field experiment at the Next-Generation Ecosystem Experiments (NGEE) sites in Barrow, Alaska. The model describes seasonal dynamics of temperature and the long-term ground motion near the ice wedges and helps to explain destabilization of the ice wedges north of Alaska's Brooks Range.
    Description
    Thesis (M.S.) University of Alaska Fairbanks, 2017
    Table of Contents
    Introduction -- Chapter 1. Simulation of temperature dynamics around a stable ice wedge -- Chapter 2. Simulation of ice wedge degradation -- Conclusion -- References.
    Date
    2017-05
    Type
    Thesis
    Collections
    College of Natural Sciences and Mathematics
    Theses (Geosciences)

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