Ice-shelf deflections modelled with a full 3D elastic model

Abstract:

Ice-shelf flexure modelling was performed using a full 3D finite-difference elastic model, which takes into account sub-ice-shelf seawater flow. The sub-ice seawater flow was described by the wave equation (Holdsworth and Glynn, 1978), so the ice-shelf flexures result from the hydrostatic pressure perturbations in sub-ice seawater. The modelling of ice-shelf vibrations was successfully performed in (Holdsworth and Glynn, 1978) by employing of the thin-plate approximation. The numerical simulation has shown that the modelling of the ice-shelf vibrations can be performed in the full model, which links well known momentum equations with the wave equation for non-viscous fluid, i.e. for sub-ice seawater. Nevertheless, the numerical simulation reveals that the numerical solution stability requires the application of an additional method in the numerical approximation. The aim of this work is in an attempt to apply an additional approximation in the boundary conditions to improve the numerical stability of the model. The second purpose is to obtain eigen-frequencies of the system, which includes an ice-self and sub-ice water, and to investigate the ice-shelf geometry impact to the eigen-frequencies (in particular, the crevasses effect on the eigen-frequencies). The numerical experiments were carried out for the thin plate of ice with changing ice thickness (with trapezoidal profile along the center line) and with different spreads, and for harmonic temporal and spatial ingoing pressure perturbations.