Roles of marine ice, rheology, and fracture in the flow and stabilityof the Brunt/Stancomb-Wills Ice Shelf

摘要

Marine ice, sometimes as part of an ice mélange, significantly affects ice shelf flowand ice fracture. The highly heterogeneous structure of the Brunt/Stancomb-Wills IceShelf (BSW) system in the east Weddell Sea offers a rare setting for uncovering thedifference in rheology between meteoric and marine ice. Here, we use data assimilation toinfer the rheology of the Brunt/Stancomb-Wills Ice Shelf by an inverse control methodthat 'combines interferometric synthetic aperture radar measurements with numericalmodeling. We then apply the inferred rheology to support the hypothesis attributing theobserved 1970s ice shelf flow acceleration to a change in the stiffness of the ice mélangearea connecting Brunt proper with Stancomb-Wills and to examine the consequences offrontal rift propagation. We conclude that while the Brunt/Stancomb-Wills system iscurrently not susceptible to extreme fragmentation similar to that of the Larsen B IceShelf in 2002, our inverse and forward modeling results emphasize its vulnerability todestabilization by relatively rapid changes in the ice mélange properties, resulting fromthe interaction of its marine ice component with ocean water, or by the further propagationof a frontal rift.