This award is for support for three years of funding for a project designed to answer two questions of critical importance to understanding the ice flow of the West Antarctic ice sheet: 1) Are the Ross ice streams (B, D, and E) currently surging?, and 2) What has been the buttressing effect of an enlarging Crary Ice Rise on the flow of ice stream B? Both questions will be answered based on a combination of data collected on the surface, from the air and from space. While many past indications of change in West Antarctica have been based on interpolations and calculations with large uncertainties, these measurements will be direct, making use of rapid and accurate GPS positioning to minimize field logistic requirements. Direct measurement of expected thinning in the upper portion of ice stream D and repeated satellite image measurements at the heads of ice streams B, D, and E to detect the inland migration of the onset area (as is required by sustained surging) will enable a test of a surge hypothesis developed by Bindschadler. The buttressing impact of Crary Ice Rise on ice stream B's flow will be studied by comparing new measurements of ice thickness, surface elevation and velocity with data collected during the 1950s, 1970s and 1980s, providing a multi-decadal time-series of change.
