Sensitivity of the divide position at Siple Dome, West Antarctica to boundary forcing

A linearized perturbation about a two-dimensional Vialov-Nye icesheet profile is used to investigate the sensitivity of the divide position at Siple Dome, West Antarctica, to small changes in the accumulation pattern and in the elevation of its lateral boundaries at the margins of Ice Streams C and D. Relaxation time-scales for the icesheet surface and divide position are derived from the perturbation theory. For Siple Dome, these time-scales are short: 450-800 years for surface adjustment, and 200-350 years for divide position adjustment. These short time-scales indicate that Siple Dome responds quickly to forcing at its boundaries. Therefore, the recent migration of the Siple Dome divide (determined from previous work) is probably a response to an ongoing, sustained forcing rather than a response to a long-past climate event such as the transition from the Last Glacial Maximum to the Holocene. Based on our analysis, the inferred rate of migration of the Siple Dome divide could be attained be/':