A "continuity-index" for assessing ice-sheet dynamics from radar-sounded internal layers

Radio-echo sounding (RES) of polar ice sheets reveals extensive internal layering. The degree of continuity of internal layering holds critical information about the ice-flow field, but previous analyses of this parameter have been limited to qualitative classications. Here we present a newly-developed quantitative method for analyzing internal layer continuity – named the continuity-index. Signicantly, our new method for analyzing internal layers is readily transferable across RES datasets, offering promise for data-led assessments of past and present flow dynamics across large areas of Antarctica and Greenland. When applied to data from Pine Island Glacier (PIG), WestAntarctica, the new method clearly identifies a continuum of discontinuity of internal layers that corresponds with the current ice-velocity field. The analysis provides further support that the main trunk and tributaries are unlikely to have undergone significant migration since the deposition of the internal layering.