A thermo-mechanical terrestrial model of Arctic coastal erosion

Although the Arctic comprises one-third of the global coastline and has some of the fastest eroding coasts, current tools for quantifying permafrost erosion are unable to explain the episodic, storm-driven erosion events that occur in this region. In this paper, we present a novel multi-physics finite element model for the numerical simulation of Arctic coastal permafrost degradation: the terrestrial component of the Arctic Coastal Erosion (ACE) model. This model is comprised of two main ingredients: (1) a solid mechanics model that calculates the three-dimensional (3D) stress, strain and displacement fields of the underlying permafrost developing in response to a frozen water content dependent plasticity model, and (2) a novel thermal model governing the 3D heat conduction and solid–liquid phase change occurring within the permafrost. These two physics sets are coupled via a sequential thermo-mechanical coupling scheme developed within the Albany LCM open-source finite element code. Unlike prior approaches, our modeling methodology enables failure from any allowable deformation (block failure, thermo-denudation, thermo-abrasion); moreover, failure modes develop from constitutive (rather than empirical) relationships inherent in the underlying finite element model. Elements are dynamically removed from the underlying finite element mesh so as to simulate transient permafrost erosion events. Our thermo-mechanical terrestrial model is evaluated on a pseudo-realistic problem in which a slice of permafrost is exposed to realistic oceanic and atmospheric forcing boundary condition data occurring at Drew Point, Alaska in July 2018.