Impact of marine processes on flow dynamics of northern Antarctic Peninsula outlet glaciers
Helmut Rott, Jan Wuite, Jan De Rydt, G. Hilmar Gudmundsson, Dana Floricioiu, Wolfgang Rack
Abstract
Tuckett et al. 1 report on short-term events of ice flow acceleration on five outlet glaciers of the northern Antarctic Peninsula and their relation to numerical model output of surface melt. The authors argue that the delivery of surface meltwater to the glacier bed transiently increases the basal water pressure and enhances basal motion, causing near-instantaneous flow acceleration followed by subsequent drainage causing deceleration. An outdated version of the grounding line (GL) vector, separating grounded and floating glacier ice, is used so that the majority of the analyzed velocity points are located on floating sections of glacier termini where meltwater drainage does not have any effect on subglacial water pressure. Our independent analysis of glacier surface velocities exhibits for the speed-up events only marginal changes in velocity on grounded ice and a significant increase of velocity on floating glacier sections progressing on prefrontal sea ice and ice mélange, clear evidence for the dominant influence of ocean dynamic forcing as previously reported by refs. 2 , 3 , 4 .