This award provides support for a three-year project to study the control of ice-till interactions on the evolution and stability of ice streams and ice sheets. As part of this project, an extensively tested numerical ice stream model will be merged with a new physical framework for treatment of sub-ice stream processes which control the commencement, evolution, and cessation of ice streaming. This framework, called the undrained-plastic -bed (UPB) model, is based on observations of physical condition beneath Ice Stream B, in West Antarctica. This model will be applied to the drainage basins of Ice Streams B and E to test four important hypotheses: 1) that the model can reproduce the main features of the observed ice stream velocity distribution; 2) that the model may produce a relatively abrupt ice stream stoppage; 3) that a significant imbalance of the West Antarctic ice streams may be caused in the near future by internal instabilities and 4) that imbalance of the ice streams may also be caused by either an increase in ice surface temperature or a doubling of snow accumulation rates. The proposed research will provide an important new advancement in the science of ice sheet modeling, while yielding predictions on ice stream behavior that may become testable in the near future.
