Relationships Between Internal Stratigraphy and Ice Flow of the Greenland Ice Sheet

Alexandria Nicole Mabrey

Several studies of the Antarctic ice sheet have found correlations between the continuity of its internal stratigraphy and ice flow, leading to an improved understanding of the instability of fast-flowing regions. Here we use airborne radar data acquired across the whole of the Greenland ice sheet by CReSIS and NASA’s Operation IceBridge campaigns to perform similar analyses, aiming to extend previous work exploring its northeastern sector. These data possess extensive internal stratigraphy throughout large sectors of the ice sheet. We examine the continuity of this stratigraphy using the recently developed “continuity index”, which quantifies horizontal variability in the vertical gradient of the internally reflected power for each radar waveform. The continuity index is calculated using minimally processed radar data and can distinguish regions of continuous, discontinuous and absent stratigraphy. Our Greenland-wide continuity index is compared with modern ice-flow speeds to understand the long-term spatiotemporal variability in fast-flow conditions. We find correlations between areas of disrupted stratigraphy (low continuity index), fast ice flow, and apparent basal freeze-on.

Supervisors: Ginny A Catania, Joseph A MacGregor