Viscous and viscoelastic stress states at the calving front of Antarctic ice shelves

Abstract

ABSTRACT. Calving mechanisms are still poorly understood and stress states in the vicinity of ice-shelf fronts are insufficiently known for the development of physically motivated calving laws that match observations. A calving model requires the knowledge of maximum tensile stresses. These stresses depend on different simulation approaches and material models. Therefore, this study compares results of a two-dimensional (2-D) continuum approach using finite elements with results of a onedimensional (1-D) beam model elaborated in Reeh (1968). A purely viscous model, as well as a viscoelastic Maxwell model, is applied for the 2-D case. The maximum tensile stress usually appears at the top surface of an ice shelf. Its location and magnitude are predominantly influenced by the thickness of the ice shelf and the height of the freeboard, the traction-free part at the ice front. More precisely, doubling the thickness leads to twice the stress maximum, while doubling the freeboard, based on changes of the ice density, results in an increase of the stress maximum by 61%. Poisson's ratio controls the evolution of the maximum stress with time. The viscosity and Young's modulus define the characteristic time of the Maxwell model and thus the time to reach the maximum principal stress.

The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet

“…The model is the one of Lhomme et al (2005), re-implemented in GRISLI by Quiquet et al (2013). We use a semi-Lagrangian scheme following Clark and Mix (2002) in order to avoid the numerical instabilities of Eulerian schemes and information dispersion of Lagrangian schemes (Rybak and Huybrechts, 2003). For each time step, the back trajectories of each grid points are computed and trilinearly interpolated onto the model grid.…”

Modeling Ice Shelf/Ocean Interaction in Antarctica: A Review

“…A suite of models has been developed to represent the drift and melting of icebergs in the ocean (e.g., Merino et al, 2016). Several physics-based models have recently been suggested for the calving process (e.g., Christmann et al, 2016), but to derive calving rates within ice sheet models, more phenomenological approaches (e.g., Albrecht et al, 2011) have prevailed so far. A robust, physics-based description of the calving process and the embedding of drifting icebergs in ocean models will be one of the major challenges in the upcoming years in order to allow for a full description of the ice mass budget and ocean freshwater fluxes.…”

The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet

“…The inclusion of a physically based calving scheme (e.g. Christmann et al, 2016) would be a significant model improvement for future model revisions.…”