UC Irvine

ERS images of the two ends of the ice front of the Filchner-Ronne Ice Shelf, Antarctica, were utilized interferometrically to study the deformation rate of the ice shelf in response to viscous creep. On the western flank of Berkner Island (BI), near Hemmen Ice Rise (HIR), a time series of ERS data acquired in Feb 1992, in both ascending and descending mode, and with a 3-day time interval, were utilized to map the ice velocity in two dimensions. Finite-element ice-shelf flow simulations are compared with the ERS interferograms to interpret the ice motion in terms of the physical constraints on ice-shelf flow. Our efforts to fit artificial interferograms generated with model velocity output suggest that the flow regime is strongly influenced by three processes. First, a void-creation process responsible for rifts at coastal margins tends to uncouple the ice shelf from the ice rise and neighboring coast of BI. Second, sea ice within the void space appears to act as a binding agent between discrete ice-shelf fragments, allowing rigid-body rotations of these fragments. Third, strain rates appear to be enhanced in a narrow zone adjacent to HIR, implying significant strain softening along the boundary. We believe that SAR interferogram/model intercomparison represents a powerful impetus toward the development of better, more physically realistic ice-shelf flow models.