Abstract

Internal Ice Layer Mapping and Geophysical Analysis of Jakobshavn Glacier, Greenland
Timothy Godaire and Alexandra Arntsen, Dr. George Tsoflias, Dr. Leigh Stearns, Dr. Kees van der Veen, and Anthony Hoch, Center for Remote Sensing of Ice Sheets, the University of Kansas, Lawrence, KS 66045

Located on the West coast of Greenland, Jakobshavn Glacier has the highest mass flux of any outlet glacier on the ice sheet. Since 1997, its velocity has more than doubled from 5,700 to greater than 12,600 m/yr with rapid retreat and instability (Joughin et al., 2004). In order to better model mass balance of the polar ice sheets, it is important to understand the dynamics of Jakobshavn. Using 2008 Greenland Airborne Radar Survey conducted by CReSIS, twelve internal layers were traced along flight survey lines of a 350km by 150km grid. With the picked layers, topography was mapped, thicknesses of adjacent layers were computed and mapped, and general zonal trends were analyzed. From layer topographical maps, it was evident that bed topographical features are visible in all layers, but are more prominent deeper in the ice column. Thickness maps showed thicker portions of each layer occurring over bed channels. When analyzing zonal ice column trends, it was observed that thinning trends occurred from North to South in shallow layers, from East to West in intermediate layers, and from Southeast to Northwest in deeper layers. Preliminary investigation using GRIP ice core data suggests the interface between intermediate and deep zones coinciding with the end of the Younger Dryas climatic event. Also observed was the ratio of each zone to the total ice thickness throughout the grid. The shallow portion of the ice column is more significant further West, the intermediate zone remains relatively constant in all directions, and the deep zone is less significant further West. Our observations demonstrate that high resolution 3D gridding can increase knowledge of glacial deformation and movement to improve ice flow models.