Abatement of Ocean-Wave Impact by Crevasses in an Ice Shelf

Abstract

Forced ice-shelf oscillations modeling was undertaken employing a full 3D finite-difference model of an elastic ice shelf that was coupled to a treatment of under-shelf seawater flux. The seawater flux was described by the wave equation, which includes the pressure excitements in the shallow water layer under the ice shelf. Thus, ice-shelf flexure was produced by hydrostatic pressure oscillations in the below-shelf seawater. Numerical calculations were performed for an idealized rectangular crevasse-ridden ice-shelf geometry. The crevasses were modeled as rectangular notches into the ice shelf. In the numerical experiments, the ice-plate flexures were forced by harmonic-entering pressure oscillations having a range of periodicities 5–250 s. The dispersion spectra derived for a crevasse-ridden ice shelf revealed “band gaps”—frequency ranges where no eigenmodes exist. The results further showed that the impact of ocean waves on the ice plate is abated from the point of view of a decrease in the spectral average amplitude in the vicinity of the spectrum where the “band gaps” are observed. This impact depends on the depth of crevasse penetration to the ice.