Ice-Shelf Basal Melt Channels Stabilized by Secondary Flow

Abstract

Ice-shelf basal channels form due to concentrated submarine melting. They are present in many Antarctic ice shelves and can reduce ice-shelf structural integrity, potentially destabilizing ice shelves by full-depth incision. Here, we describe the viscous ice response to a basal channel—secondary flow—which acts perpendicular to the channel axis and is induced by gradients in ice thickness. We use a full-Stokes ice-flow model to systematically assess the transient evolution of a basal channel in the presence of melting. Secondary flow increases with channel size and reduces the rate of channel incision, such that linear extrapolation or the Shallow-Shelf Approximation cannot project future channel evolution. For thick ice shelves ((Formula presented.) m) secondary flow potentially stabilizes the channel, but is insufficient to significantly delay breakthrough for thinner ice ((Formula presented.) m). Using synthetic data, we assess the impact of secondary flow when inferring basal-channel melt rates from satellite observations.