Glaciological observations using radio echo-sounding in temperate and cold ice

Ground based radio echo-sounding (RES) is used to map englacial and subglacial features to develop a better understanding of glacier dynamics. The effects of RES side-swipe on interpretation are investigated through a three-dimensional synthetic model. Examples of RES surveys are applied to two glaciology problems, one in cold ice, the other in temperate ice. Englacial conduits in temperate ice are mapped by three-dimensional RES surveys leading to an investigation of the behavior of englacial water flow. Existing models of englacial conduits are limited by the assumption of pressurized flow despite significant variations in observed meltwater input. Coupling a transient pressurized englacial model with an open-channel transient model shows that initial conduit geometry from formation has a greater influence on the geometry seen in RES surveys than subsequent melt. Four states of englacial conduit flow behavior are defined: (1) steady-state open-channel flow during initial model relaxation, (2) transient open-channel flow, (3) transient partially-pressurized flow, and (4) transient pressurized flow.; Long-distance two-dimensional profiles in Antarctica present an opportunity to examine the stability of West Antarctic Ice Sheet (WAIS) divides. The Amundsen Sea/Ross Sea divide is of interest for its proximity to the proposed Inland WAIS deep core site. Interpretation of the ice core climate record depends upon a complete understanding of the ice flow history of the region. Likewise, retreat of the Pine Island Glacier grounding line may translate into changes in the Pine Island Glacier/Rutford Ice Stream divide. A simple particle-tracking model examines the changes in isochronal (stratigraphic) configuration during ice sheet divide migration. The model shows that both WAIS divides are relatively stable.