This presentation will detail the calibration of the recently developed ACE (Arctic Coastal Erosion) Model, a multi-physics numerical tool which couples oceanographic and atmospheric conditions with a terrestrial permafrost domain to capture the thermo-chemo-mechanical dynamics of erosion along permafrost coastlines. The ACE Model is based on the finite-element method and solves the governing equations for conservation of energy (via heat conduction including phase change), and conservation of linear and angular momenta using a plasticity material model. Oceanographic and atmospheric boundary conditions force the evolution of a terrestrial permafrost environment, which consists of porous media made of sediment grains and pore fluid. An oceanographic modeling suite (consisting of external software packages) produces time-dependent water level, temperature, and salinity boundary conditions for the terrestrial domain. Atmospheric temperature is obtained from the ECMWF Reanalysis v5 (ERA5) dataset. Driven by these boundary conditions, 3-D solutions of temperature, stress, and displacement develop in the terrestrial domain in response to the plasticity model that is controlled by the frozen water content. Material is removed when the stress within an element exceeds the yield strength of the material and is followed by grid adaptation that captures the new geometry. This modeling approach enables failure from any allowable deformation (e.g., block failure, slumping, thermal denudation) and can treat erosion behavior over single events (hours/days), seasonally, or over several years.
A demonstration of the ACE Model will be presented for a portion of the summer 2018 conditions at Drew Point, AK, during which a block collapse event was documented with thermistor data and time-lapse photography. We demonstrate that the ACE Model can reproduce the observed erosion behavior, including niche formation/geometry, thermal denudation, and block collapse timing. This model can be used to rigorously investigate erosion drivers and how climate change will influence future erosion behavior at Drew Point, as well as typological assessment of erosion along the North Slope of Alaska to enable estimates of shoreline change at the coarse scale of Earth system models.