Finite Element Analysis of Calving From Ice Fronts

Abstract

The Antarctic ice sheet has almost no net annual ablation on its surface, so most mass losses are by iceberg calving along its perimeter, which may be either grounded in shallow water or floating in deep water. An ice cliff forms along the perimeter in both cases. Wave action undercuts ice margins in the tide-water zone along beaches, and causes coastal calving if the rate of undercutting compares with the forward ice velocity. If the ice velocity is sufficiently greater, the ice sheet advances into deeper water and becomes a float at depths of 200 to 300 m (Robin 1979). A floating ice shelf then forms and icebergs calve along the ice front. Iceberg calving along this ice front may be due to several causes (Holdsworth 1977,Robin 1979). Since iceberg calving, either from ice shelves or in the tidewater zone of beaches between ice shelves, is the principal ablation mechanism of the Antarctic ice sheet, it is important to understand calving dynamics quantitatively. This paper presents the results of a finite-element examination of calving along floating margins of the ice sheet.