What Determines the Shape of a Pine-Island-Like Ice Shelf?

Abstract

<p>Ice shelf shape directly controls ocean heat intrusions, melting near the grounding line, and buttressing. Little is known about what determines ice-shelf shape because ice-ocean coupled simulations typically aim at projecting Antarctica's contribution to sea-level rise and they do not resolve small-scale ice-ocean interactive processes. We conduct ice-ocean coupled simulations for an idealized high-resolution, Pine-Island-like model configuration. We show that ocean melting and ice stretching caused by ice acceleration both thin the ice shelf from the grounding line toward the ice shelf front, while ice divergence from the center advects ice toward the ice shelf edges, compensating melt-driven thinning along the across-shelf direction. We separate the ice dynamical component of ice shelf thinning from melt-induced thinning, as a way to understand processes that occur around the grounding zone, where satellite measurements cannot provide a direct measure of basal melt. In the case of the simulated idealized Pine-Island-like ice shelf, ∼75% and ∼25% of ice-shelf thinning is driven by ice shelf melting and ice stretching, respectively. For observations along Pine Island Ice Shelf flowlines, we also confirm that ocean melting and ice acceleration are the two main terms shaping the ice shelf. We also highlight the importance of shallow-depth melting for determining the ice shelf front thickness and ice shelf shape. Recent studies show that the ice shelf shape close to the ice shelf front can control ice shelf buttressing, ice shelf/glacier evolutions, and sea level rise prediction. This study suggests that ice-ocean interactive processes between the entire ice shelf and the ocean alter ice shelf shape including ice shelf front thickness, despite that ice-ocean interactive processes only close to grounding zones have attracted much attention in the past decade. </p>